Co-reporter:Yongfeng Zhu, Huifang Zhang, Wenbo Wang, Xiushen Ye, ... Aiqin Wang
Chemical Engineering Research and Design 2017 Volume 125(Volume 125) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.cherd.2017.07.021
•Magnetic porous spheres were prepared via O/W Pickering HIPEs.•Silanized attapulgite influence greatly the pore structure of porous sphere.•Magnetic porous spheres exhibit excellent adsorptive property for Rb+ and Cs+.•Magnetic porous spheres can be easily separated and exhibit excellent reusability.A series of magnetic porous hydrogel spheres were prepared from the oil in water (O/W) Pickering emulsion stabilized with silicone-modified magnetic attapulgite (MAPT), using hydroxypropyl cellulose (HPC) as the grafting backbone and acrylic acid (AA) as the monomer. The structure, morphologies and physico-chemical features of the Pickering emulsions and the hydrogel spheres were characterized by TEM, SEM, XRD and TGA techniques. The results revealed that the Fe3O4 was attached on the surface of APT with good dispersion, and the magnetic APT (MAPT) was modified successfully with silane. The emulsion with HPC, AA, initiator and crosslinker inside can be directly dropped into hot liquid paraffin to form hydrogel sphere. The rod-like APT as the stabilizer facilitated to form open pore and interconnected pores. The magnetic porous hydrogel sphere can rapidly adsorb the rare elements Rb+ and Cs+, with the maximum adsorption capacities of 232.46 and 239.88 mg/g, respectively. The adsorbed Rb+ and Cs+ ions can be recovered by a simple desorption process, and the hydrogel sphere also showed excellent reusability after five consecutive adsorption–desorption cycles. This porous sphere with excellent adsorption capability and rate is potential adsorbent for the adsorption and enrichment of rare metals Rb+ and Cs+.Download high-res image (241KB)Download full-size image
Co-reporter:Yongfeng Zhu, Wenbo Wang, Huifang Zhang, Xiushen Ye, Zhijian Wu, Aiqin Wang
Chemical Engineering Journal 2017 Volume 327(Volume 327) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.cej.2017.06.169
•Recyclable magnetic porous spheres were prepared from O/W Pickering emulsion.•The s magnetic porous pheres show homogeneous and regular pore structure.•The spheres have the adsorption capacities of 310 mg/g for Rb+ and 448 mg/g for Cs+.•The spheres are easy to be separated from solution and regenerated for reuse.A novel recyclable magnetic porous sphere adsorbent is prepared by grafting acrylic acid (AA) onto hydroxypropyl cellulose (HPC) through a Pickering emulsion integrated precipitation polymerization and used for the enrichment of scattered strategic metals Rb+ and Cs+. The modified Fe3O4 nanoparticles can not only stabilize the Pickering emulsion template for forming pores, but also make the adsorbent easy to be separated from solution by magnetic field. The adsorption results indicate that the adsorption of Rb+ and Cs+ by the sphere adsorbent rapidly reaches equilibrium within 15 and 30 min, respectively. The saturated adsorption capacities reach 310 and 448 mg/g for Rb+ and Cs+, respectively, which are better than that reported in most of literatures. Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses confirm that the chemical complexation of –COO− and –OH with Rb+ and Cs+ contribute mainly to the adsorption. In addition, the adsorbent is very easy to be recovered and regenerated, and the adsorption capacity does not decrease significantly even after five consecutive adsorption–desorption cycles, as compared with the initial adsorption capacity. The results of dynamic adsorption experiments show that the flow rate, initial ion concentration and column height have an effect on the adsorption capacities of Rb+ or Cs+. In a word, this recyclable sphere adsorbent is promising to be used for the efficient adsorption and enrichment of rare metals.Download high-res image (144KB)Download full-size image
Co-reporter:Jixiang Xu, Wenbo Wang, Aiqin Wang
Powder Technology 2017 Volume 318(Volume 318) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.powtec.2017.05.032
•Stable FM/Pal hybrid material was prepared by high pressure homogenization.•High-pressure homogenization promotes the dispersion of Pal and loading of FM.•FM existed on external surface or fixed into tunnel of Pal by H-bonds.•The hybrid materials show improved adsorption capacity for Pb(II) than Pal.High-pressure homogenization was employed to incorporate formamide (FM) in palygorskite (Pal) for the fabrication of aminated hybrid materials. The interactions of FM molecules with Pal and the positions of FM molecules inside the structure of Pal after hybridization and heat treatments were investigated. It was found that high-pressure homogenization could improve the dispersion of Pal bundles and facilitate the additional incorporation of FM molecules into the tunnels or channels of Pal and that supported the formation of stable FM/Pal hybrid materials. Spectroscopic and thermal analysis results confirmed that FM molecules could attach to Pal via H-bonds. The tunnel of Pal remained perfect after calcination at 380 °C owing to the incorporated FM molecules. The adsorption capacity of the homogenized FM/Pal hybrid material towards Pb(II) (58.4 mg·g− 1) was improved in comparison with the raw Pal (32.2 mg·g− 1) after calcination at 380 °C. The enhanced interactions between the organic species and Pal structure via high-pressure homogenization provided an alternative strategy to design new stable hybrid materials.Download high-res image (277KB)Download full-size image
Co-reporter:Guangyan Tian, Wenbo Wang, Dandan Wang, Qin Wang, Aiqin Wang
Powder Technology 2017 Volume 315(Volume 315) pp:
Publication Date(Web):15 June 2017
DOI:10.1016/j.powtec.2017.03.044
•Environment friendly red hybrid pigment was synthesized based on attapulgite.•Attapulgite is essential to form such red pigment and restrain aggregation of Fe2O3.•The hybrid pigment shows bright red color (a* = + 36.3) and superior stability.•Low-cost and eco-friendly red pigments from natural attapulgite were achieved.Novel environment friendly inorganic hybrid pigments with bright red colors and good stability were successfully prepared by a one-pot hydrothermal reaction of natural attapulgite (APT) with Fe(III) salts, without addition of any chemical precipitants. It has been revealed by systematic structure characterizations that APT is essential to form the red hybrid pigment, and the Fe2O3 nanoparticles were in-situ formed and anchored on APT to form a stable composite. The hybrid pigment with the composition of 29.61% SiO2 and 68.37% Fe2O3 showed bright red color with the a* coordinate value of + 36.3, which was better than the same kinds of commercial red pigments. The color of the hybrid pigments can be tuned by only altering the dosage of Fe(III) or reaction time, and accordingly a series of hybrid pigments with the colors of light amber, orange red and bright red were obtained. Moreover, the red hybrid pigments can tolerate lights, acids, alkalis and organic solvents, and suspend well in water and alcohol media, and are able to be easily coated on different substrates, e.g., glass, wood, ceramic, cotton fabric, and paper.Download high-res image (87KB)Download full-size image
Co-reporter:Feng WANG, Wenbo WANG, Yongfeng ZHU, Aiqin WANG
Journal of Rare Earths 2017 Volume 35, Issue 7(Volume 35, Issue 7) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/S1002-0721(17)60966-9
CTS-g-(AA-co-SS)/ISC hybrid hydrogel adsorbent with crosslinked network structure and superior adsorption performance for rare-earth metal ions was successfully synthesized in aqueous solution by a simple one-step free-radical grafting polymerization reaction among acrylic acid (AA), sodium p-styrenesulfonate (SS) and chitosan (CTS) using illite/smectite clay (ISC) as the inorganic additive. The structure of the as-prepared CTS-g-(AA-co-SS)/ISC hydrogel adsorbent was characterized, and the reaction parameters such as AA/SS molar ratio and ISC content were optimized, and the effects of pH values, initial concentration and contact time on the adsorption performance for Ce(III) and Gd(III) were systematically evaluated. It was found that the maximum adsorption capacities of the hydrogel adsorbent toward Ce(III) and Gd(III) reached 174.05 and 223.79 mg/g, respectively, and the adsorption quickly achieved equilibrium within 15–20 min. The adsorbed Ce(III) and Gd(III) could be easily desorbed for recovery, and the used adsorbent was able to be regenerated for reuse. After five adsorption-desorption cycles, the regenerated adsorbent could still retain the adsorption capacities that were close to the initial value. The adsorption process was well described by pseudo-second-order kinetic mode and the Langmuir isotherm model, and the chemical complexation between ions and –COO– was mainly responsible for the high adsorption capacity. As a whole, the hybrid hydrogel adsorbent was potential to be used for the adsorption and recovery of Ce(III) and Gd(III) from water.Granular hydrogel adsorbent with the maximum adsorption capacity of 174.05 mg/g for Ce(III) and 223.79 mg/g for Gd(III) was prepared by a one-step green solution polymerizationDownload high-res image (168KB)Download full-size image
Co-reporter:Anjie Zhang, Bin Mu, Zhihe Luo, Aiqin Wang
Dyes and Pigments 2017 Volume 139(Volume 139) pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.dyepig.2016.12.055
•Bright blue and low-cost halloysite/CoAl2O4 hybrid pigments were successfully prepared.•Introducing of halloysite decreased the calcining temperature to form spinel-type CoAl2O4.•Incorporating of halloysite was favor of enhancing the color performance of pigments.•Hybrid pigments exhibited good suspension stability in water-based painting.•Hybrid pigments could be sprayed onto various substrates.Bright blue CoAl2O4/halloysite hybrid pigments were prepared via combining chemical co-precipitation and calcination process. The obtained hybrid pigments were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, high resolution transmission electron microscopy, and ultraviolet–visible spectroscopy. The introduction of halloysite not only decreased the calcining temperature for formation of spinel-type CoAl2O4, but also enhanced the color properties of CoAl2O4 pigments including hue, brightness and chroma. The hybrid pigments incoropated 60% halloysite presented excellent color properties (L* = 54.6, a* = −2.5, b* = −50.4, h* = 262.21, and C* = 47.35) and excellent environmental resistance tolerance toward acid, alkali and ultraviolet light. In particular, the hybrid pigments could be well dispersed into water-based paint with good suspension stability. It indicated that the hybrid pigments could be served as a promising pigment with bright blue to be applied in various fields such as ceramics, water based paints, inks, etc.Download high-res image (445KB)Download full-size image
Co-reporter:Weibing Xu, Bin Mu, Aiqin Wang
Electrochimica Acta 2017 Volume 224(Volume 224) pp:
Publication Date(Web):10 January 2017
DOI:10.1016/j.electacta.2016.12.032
•3D hollow microtubular composites are prepared using kapok fiber as template.•Surface morphologies of the composites are dependent on the calcination temperature.•The composites with nanoflake morphology exhibits excellent electrochemical performance.•Natural kapok fiber is expected to design hollow materials for electrochemical storage.Three-dimensional hollow microtubular carbonized kapok fiber/cobalt-nickel binary oxide hybrid composites were successfully prepared based on the low-cost natural kapok fiber by combining a simple hydrothermal technique and calcination method. The three-dimensional hollow tubular structure was kept well during the preparation process. The surface morphologies of the as-prepared three-dimensional carbonized kapok fiber/cobalt-nickel binary oxide hybrids changed from the cross-linked fibrous network to the nanoflakes with the increase in the calcination temperature. The composites prepared at 600 °C for 2 h exhibited a high specific capacity with 502.4 C g−1 at discharge currents of 0.25 A g−1 in 6.0 M KOH, and the capacity retention was still maintained at 97.5% after 5000 cycles demonstrating good electrochemical stability. In addition, a hybrid supercapacitor device was also assembled using active carbon and the as-prepared composite as negative and positive electrodes, respectively. It could be operated within a wide potential window of 0.0–1.6 V with a high specific energy of 23.2 W h kg−1. In addition, the hybrid supercapacitor also exhibited excellent rate capability as well as long-term stability after 5000 cycles. The high reversible capacity of the obtained electroactive hybrid composites can be ascribed to the unique hollow tubular structure, the large surface area, the high defective carbon matrix and the synergetic effect of hybrid electroactive components. Therefore, the as-prepared three-dimensional hollow microtubular hybrids are expected to develop high-performance supercapacitor.Download high-res image (186KB)Download full-size image
Co-reporter:Weibing Xu, Bin Mu, Aiqin Wang
Electrochimica Acta 2016 Volume 194() pp:84-94
Publication Date(Web):10 March 2016
DOI:10.1016/j.electacta.2016.02.072
•Well-defined microtubular CKF/NiO composite has been prepared.•The as-prepared composites exhibit the maximum capacitance of 575.5 F g−1.•An ASC device of CKF/NiO-400-2//AC shows high energy density of 7.5 Wh kg−1.•This scalable protocol can be used to fabricate other microtubular composites.Design and fabrication of structurally optimized electrode materials using biomass materials has become one of the hottest subjects in the field of electrochemical energy storage. Hollow tubular carbonized kapok fiber/NiO composites are synthesized by a facile hydrothermal and carbonization procedure using kapok fiber as a low-cost template. Owing to their unique microtubular structure, the as-prepared composites exhibit a high specific capacitance of 575.7 F g−1 at current density of 0.5 A g−1. Furthermore, an asymmetric supercapacitor device also has been fabricated using carbonized kapok fiber/NiO composites and commercial activated carbon as the positive and negative electrodes, respectively. Because of its unique structure, high capacitive performance, and complementary potential window, the asymmetric supercapacitor device can be cycled reversibly at a cell voltage of 1.6 V in 1.0 M KOH aqueous electrolyte, delivering a high energy density of 7.5 W h kg−1 at a power density of 64.6 W kg−1. In addition, the asymmetric supercapacitor device also exhibits a superior long cycle life and the capacitance retention of the initial specific capacitance cannot found clearly degeneration after 4000 cycles. It is worth noting that this scalable protocol also can be employed to prepare other microtubular carbon/metal oxide composites with good electrochemical performances.
Co-reporter:Yongfeng Zhu, Yian Zheng, Li Zong, Feng Wang, Aiqin Wang
Carbohydrate Polymers 2016 Volume 149() pp:242-250
Publication Date(Web):20 September 2016
DOI:10.1016/j.carbpol.2016.04.107
A series of magnetic hydroxypropyl cellulose-g-poly(acrylic acid) porous spheres were prepared via O/W Pickering high internal phase emulsions (HIPEs) integrated precipitation polymerization. The structure and composition of modified Fe3O4 and porous structures were characterized by TEM, XRD, TGA and SEM. The results indicated that the silanized Fe3O4 can influence greatly the pore structure of magnetic porous sphere in addition to non-negligible impacts of the proportion of mixed solvent and co-surfactant. The adsorption experiment demonstrated that the adsorption equilibrium can be reached within 40 min and the maximal adsorption capacity was 300.00 mg/g for Cd2+ and 242.72 mg/g for Cu2+, suggesting its fast adsorption kinetics and high adsorption capacity. After five adsorption–desorption cycles, no significant changes in the adsorption capacity were observed, suggesting its excellent reusability. The magnetic porous sphere can be easily separated from the solution and then find its potential as a recyclable material for highly efficient removal of heavy metals.
Co-reporter:Guangyan Tian, Wenbo Wang, Bin Mu, Yuru Kang, Aiqin Wang
Journal of Colloid and Interface Science 2016 Volume 473() pp:84-92
Publication Date(Web):1 July 2016
DOI:10.1016/j.jcis.2016.03.058
A multifunctional palygorskite/polyaniline/Ag nanoparticles (PAL/PANI/AgNPs) nanocomposite was prepared at room temperature using a simple one-pot in-situ polymerization reaction of aniline monomers triggered by Ag(I) on the surface of natural PAL nanorods. Ag(I) served as both the oxidant and the precursor of the AgNPs, which initiated the polymerization of aniline monomers on PAL nanorods while simultaneously being reduced to form Ag0 nanoparticles (AgNPs). The in-situ formed AgNPs were evenly distributed on the surface of the PAL nanorods because the interfacial effect of PAL prevents their aggregation. The density and size of the AgNPs and the catalytic activity of the nanocomposites could be controlled by altering the molar ratio of aniline to Ag(I). The performance evaluation revealed that the nanocomposites could be used as highly active catalysts, which rapidly catalyzed the reduction of 4-nitrophenol (4-NP) within 2 min and Congo red (CR) within 10 min. The nanocomposites are also an effective adsorbent for H2PO4− able to remove 99.40% of H2PO4− (only 61.77% for raw PAL) from a solution with an initial concentration of 50 mg/L. This multifunctional nanocomposite synthesized by a simple one-pot approach is a promising material for environmental applications.
Co-reporter:Yuan Zhang, Wenbo Wang, Bin Mu, Qin Wang, Aiqin Wang
Powder Technology 2016 Volume 299() pp:261-262
Publication Date(Web):October 2016
DOI:10.1016/j.powtec.2016.05.048
This paper is a response to the comment by Roberto Giustetto on our article entitled “Effect of grinding time on fabricating a stable methylene blue/palygorskite hybrid nanocomposite”. We thank Dr. Roberto Giustetto for his interest in our recently published work, and appreciate his comment because it offers us an opportunity to present additional discussions about our work. The relevant discussion about the effect of the grinding factors on the structure and stability of dye/PAL hybrid were further clarified.
Co-reporter:Wenbo Wang, Guangyan Tian, Li Zong, Qin Wang, Yanmin Zhou, Aiqin Wang
Microporous and Mesoporous Materials 2016 Volume 234() pp:317-325
Publication Date(Web):1 November 2016
DOI:10.1016/j.micromeso.2016.07.029
•A hybrid Zn-silicate adsorbent was prepared from natural low-grade palygorskite clay.•Morphologies and crystal forms of Zn-silicates were tuned by altering the dosage of Zn2+ ions.•Zn-silicate with Si/Zn ratio of 3:1 presents the best adsorption capacity for antibiotics.•99.4% of aureomycin and 99.1% of tetracycline were removed from 200 mg/L solution.•Pore size and surface charges contribute more to adsorption than specific surface areas.A hierarchical mesoporous hybrid Zn-silicate adsorbent with superior adsorption performance for aureomycin (AMC) and tetracycline (TC) has been successfully synthesized by employing an “all-into-one” strategy and one-pot hydrothermal reaction, using naturally abundant, low-cost red palygorskite clay (RPAL), sodium silicate and zinc salts as raw materials. The morphologies and crystal forms of the Zn-silicates can be tuned by altering the dosage of Zn2+ ions. Low-crystalline sheet-like Zn-silicates were formed at the Si/Zn ratio of 3:1 and 2:1, and zinc orthosilicates were obtained at the Si/Zn ratio of 1:1 and 1:2. A systematic study on their adsorption abilities for the antibiotics AMC and TC indicates that the sheet-like Zn-silicate has higher adsorption capacity for AMC and TC than zinc orthosilicate, and the Zn-silicate with Si/Zn ratio of 3:1 has the best adsorption capacity of 384 mg/g for AMC and 337 mg/g for TC, which is obviously higher than that of RPAL (154 mg/g for AMC and 140 mg/g for TC). The adsorption properties are dependent on the pore size and surface charges, instead of specific surface area. The average pore sizes of 10.62–11.50 nm and the negative surface charge (−42.54 mV) resulting from the –Si(M)O− groups are beneficial to the adsorption for both AMC and TC. The adsorption process mainly involves with monolayer coverage, and chemo-adsorption plays a key role for the enhanced adsorption capacity. The results suggest that the Zn-silicates derived from natural abundant clay mineral have superior performance, and could be candidates to remove AMC and TC from the wastewater with high amounts of AMC and TC.
Co-reporter:Qin Wang, Bin Mu, Yuan Zhang, Junping Zhang, Aiqin Wang
Microporous and Mesoporous Materials 2016 Volume 224() pp:107-115
Publication Date(Web):April 2016
DOI:10.1016/j.micromeso.2015.11.034
•A new SiO2@FY-10G/PAL hybrid fluorescent pigment was prepared based on PAL.•PAL enhances the thermal stability of FY-10G due to the supramolecular host/guest interactions.•The fluorescence intensities of FY-10G enhanced with increasing TEOS concentration.•SiO2@FY-10G/PAL enhanced resistance to chemical and UV-light stability.A new hybrid fluorescent pigment was prepared combining the adsorption of a fluorescent yellow X-10GFF (FY-10G, a coumarin derivative fluorescent dye) on palygorskite (PAL) with the silica encapsulation by the hydrolysis of tetraethoxysilane (TEOS) using acetic acid as catalyst. The photo-stability under UV irradiation and the resistance toward acid, alkali and ethanol of the SiO2@FY-10G/PAL hybrid fluorescent pigments were systematically discussed. The results show that the introduction of PAL not only significantly influences the absorption and fluorescence spectra of the FY-10G, but also enhances the thermal stability of FY-10G due to the supramolecular host/guest interactions. The encapsulation of the silica coating can effectively improve thermal- and photo-stability of FY-10G. Moreover, the fluorescent intensity and the resistance of the hybrid fluorescent pigments to acid and organic solvent enhance with the increase of TEOS concentration.
Co-reporter:Weibing Xu, Bin Mu and Aiqin Wang
RSC Advances 2016 vol. 6(Issue 9) pp:6967-6977
Publication Date(Web):12 Jan 2016
DOI:10.1039/C5RA22469A
Well-defined porous carbon nanoflakes with a high specific surface area have been successfully prepared via pyrolytic carbonization and alkali activation treatment of an easily available kapok fiber. The details of alkali–carbon ratio, activation temperature, and activation time are optimized according to the specific surface area and the specific capacitance of the as-prepared samples. The porous carbon nanoflakes prepared at 700 °C for 2 h with an alkali carbon ratio of 5:1 possess a high specific surface area of 1634.5 m2 g−1. The specific capacitance can reach 430 F g−1 at a current density of 0.5 A g−1 in a 1.0 M H2SO4 electrolyte, and an excellent cycle stability with no obvious decrease is observed after 5000 cycles. In addition, the assembled symmetrical supercapacitor base on the sample exhibits an energy density of 7.85 W h kg−1 at a power density of 125 W kg−1. The favourable capacitive performances indicate that the low-cost kapok fiber can serve as a new resource of carbonaceous materials for high-performance supercapacitors.
Co-reporter:Weibing Xu, Bin Mu and Aiqin Wang
New Journal of Chemistry 2016 vol. 40(Issue 3) pp:2687-2695
Publication Date(Web):19 Jan 2016
DOI:10.1039/C5NJ03734D
Montmorillonite/polyaniline/metal oxide (hydroxide) (MMT/PANI/MO(OH)) ternary hybrid composites were synthesized by a simple hydrothermal process based on the common adsorbents of montmorillonite/polyaniline (MMT/PANI) composites after adsorption of metal ions. The MMT/PANI composites were fabricated by the intercalation of polyaniline in the clay layers using in situ intercalative oxidative polymerization of the protonated aniline. The as-prepared product of MMT/PANI-1.4/Co3O4 as electrode materials for supercapacitors exhibited a high specific capacitance of 234 F g−1 at discharge currents of 0.1 A g−1 in 1.0 M KOH aqueous solution, and the capacitance retention after 1000 cycles was about 97.5% indicating a better cycling stability. This strategy may provide a feasible way for transformation of the adsorbent loading of metal ions into electrode materials for supercapacitors.
Co-reporter:Weibing Xu, Bin Mu, Wenbo Zhang and Aiqin Wang
RSC Advances 2016 vol. 6(Issue 72) pp:68302-68311
Publication Date(Web):04 Jul 2016
DOI:10.1039/C6RA16899J
Hollow micro-/nano-structured materials have been recognized as a promising material for applications in energy-related systems, especially supercapacitors. In this study, polyaniline (PANI) microtubes derived from low-cost natural kapok fibers were facilely fabricated as the electrode materials of supercapacitors. The kapok fiber templates were removed facilely using a NaOH solution after the in situ polymerization of aniline on the outer surface of the kapok fibers. The PANI microtubes etched using 6.0 M NaOH for 60 min exhibit the highest specific capacitance of 667 F g−1 in 1.0 M H2SO4. Interestingly, the as-prepared PANI microtubes showed excellent cycle stability with capacitance retention of 60.7% compared to the origin capacitance after 10000 cycles. Asymmetric supercapacitors, which were fabricated based on the positive electrode of the as-prepared PANI microtubes and negative electrode of the commercial activated carbon showed a high energy density of 14.1 W h kg−1. The superior electrochemical performance of the PANI microtubes might be due to their hollow structure, which can facilitate the ion diffusion and improve the utilization of the electroactive PANI during the charge–discharge processes. In addition, the residual kapok fiber can effectively relieve the contraction/expansion of PANI during the doping/dedoping processes.
Co-reporter:Guangyan Tian, Wenbo Wang, Li Zong, Yuru Kang and Aiqin Wang
RSC Advances 2016 vol. 6(Issue 48) pp:41696-41706
Publication Date(Web):13 Apr 2016
DOI:10.1039/C6RA03981B
Palygorskite (PAL) has been widely used for adsorption removal of dyes from wastewater, but the dye-loaded PAL is usually discharged as solid waste because it is hardly regeneratable by conventional elution processes. As the aim was to efficiently utilize the dye-loaded PAL waste, we employed a facile one-pot hydrothermal process to transform the spent methyl violet (MV)-loaded PAL into multifunctional ternary palygorskite/carbon/Ag nanoparticles (PAL/C/AgNPs) nanocomposites in the assistance of AgNO3. The MV-loaded PAL serves as a carbon precursor, reducer of Ag(I) and supporter of the in situ formed AgNPs. Structure characterizations confirmed that the MV dye was transformed into carbon species, and AgNPs were formed on the PAL with good dispersion, and the addition of Ag(I) ions promoted carbonization of the MV molecules. The as-prepared nanocomposites exhibited excellent adsorption and catalytic performance. Adsorption evaluation showed that the nanocomposite prepared at 5 mass% of AgNO3 dosage gives the best adsorption properties, and 99.2% of methylene blue (MB), 86.9% of MV, 68.7% of chlortetracycline hydrochloride (CTC) and 46.2% of tetracyclines (TC) were rapidly removed from 100 mg L−1 of the aqueous solution using 0.5 g L−1 of the adsorbent. The removal ratio increased with increasing dosage of adsorbent, and the minimum usage amounts of adsorbent for the thorough removal of MB, MV, CTC and TC molecules were 1.0 g L−1, 1.2 g L−1, 3.5 g L−1 and 4.5 g L−1, respectively. Moreover, the nanocomposites could rapidly catalyze the conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) within 6.5 min with a catalytic rate constant of 0.0120 s−1, and the catalytic activity is still retained after 8 cycles of reuse. In addition, the nanocomposite can be re-generated into new adsorbents by the same hydrothermal process after adsorption of organic matters, which open a new sustainable avenue to efficiently utilize waste dye-loaded PAL and develop new adsorption and catalysis materials.
Co-reporter:Jie Tang, Bin Mu, Wenbo Wang, Maosong Zheng and Aiqin Wang
RSC Advances 2016 vol. 6(Issue 43) pp:36534-36543
Publication Date(Web):07 Apr 2016
DOI:10.1039/C5RA26362J
Manganese dioxide/carbon/attapulgite ternary composites were fabricated via a facile hydrothermal method based on spent bleaching earth. It is worth noting that the residual organic matter of the spent bleaching earth not only served as a low-cost available carbon precursor, but also as a reductant for the formation of manganese dioxide based on the redox with KMnO4. Using the organic dye of Brilliant green and the heavy metal ion of Pb(II) as model pollutants, the effect of the critical factors on the adsorption properties have been systematically investigated, including the sample preparation conditions, contact time and initial concentration of pollutants. The results reveal that the adsorption properties of the as-prepared composites are well dependent on the concentration of KMnO4, and the maximum adsorption capacity toward Brilliant green and Pb(II) can reach 199.99 mg g−1 and 166.64 mg g−1 while the concentration of KMnO4 is 12% and 16%, respectively.
Co-reporter:Feng Wang;Yian Zheng;Yongfeng Zhu;Aiqin Wang
Water, Air, & Soil Pollution 2016 Volume 227( Issue 4) pp:
Publication Date(Web):2016 April
DOI:10.1007/s11270-016-2812-4
A granular hydrogel of chitosan-g-poly(vinylimidazole-co-2-acrylamido-2-methyl propane sulfonic acid) was successfully synthesized by one-step free radical polymerization based on the grafting backbone of chitosan and the monomers of vinylimidazole and 2-acrylamido-2-methyl propane sulfonic acid. The resulting hydrogel could be used as the adsorbent for the efficient and selective removal of Hg2+ ions from the aqueous solution. The adsorption results could be well described by the pseudo-second-order kinetic mode and the Langmuir isotherm model with a maximum adsorption capacity of 363.55 mg/g for Hg2+. Furthermore, the as-prepared granular hydrogel exhibited an excellent cycling stability for the adsorption of Hg2+ after multiple repeated adsorption-desorption process. It suggested that the obtained granular hydrogel has potential application for Hg2+ removal and recovery from wastewater.
Co-reporter:Bin Mu and Aiqin Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 1) pp:281-289
Publication Date(Web):04 Nov 2014
DOI:10.1039/C4TA05367B
Multifunctional superparamagnetic attapulgite/Fe3O4/polyaniline (APT/Fe3O4/PANI) nanocomposites have been fabricated by a one-pot process using Fe(III) as the oxidant for aniline and the precursor of Fe3O4 in the presence of attapulgite. The introduction of attapulgite can effectively induce the uniform encapsulation of polyaniline and Fe3O4 nanoparticles on the surface of attapulgite to form the Anthurium andraeanum-like structure, preventing the formation of free aggregates of polyaniline and Fe3O4 nanoparticles. The morphologies and the magnetic properties of the as-prepared nanocomposites can be facilely controlled by adjusting the molar ratio of aniline to Fe(III). The APT/Fe3O4/PANI nanocomposites can be used as an adsorbent for the removal of dyes and the enrichment of Au(III) from the solution. In addition, the adsorbed Au(III) could be reduced to elemental gold to obtain APT/Fe3O4/PANI supported Au nanocomposites due to the good redox activities of PANI, which exhibited excellent catalytic activity toward the catalytic reduction of 4-nitrophenol in the presence of NaBH4.
Co-reporter:Lei Wu, Lingxiao Li, Bucheng Li, Junping Zhang, and Aiqin Wang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 8) pp:4936
Publication Date(Web):February 11, 2015
DOI:10.1021/am5091353
Magnetic, durable, and superhydrophobic polyurethane (PU) sponges were fabricated by chemical vapor deposition (CVD) of tetraethoxysilane (TEOS) to bind the Fe3O4 nanoparticles tightly on the sponge and then dip-coating in a fluoropolymer (FP) aqueous solution. The sponges were characterized using scanning electron microscopy and other analytical techniques. The effects of CVD time of TEOS and FP concentration on wettability, mechanical properties, oil absorbency, and oil/water selectivity of the sponges were also investigated. The sponges exhibit fast magnetic responsivity and excellent superhydrophobicity/superoleophilicity (CAwater = 157° and CAoil ≈ 0°). The sponges also show very high efficiency in oil/water separation and could, driven by a magnet, quickly absorb floating oils on the water surface and heavy oils under water. Moreover, the PU@Fe3O4@SiO2@FP sponges could be used as membranes for oil/water separation and for continuous separation of large amounts of oil pollutants from the water surface with the help of a pump. The in turn binding of Fe3O4 nanoparticles, SiO2, and FP can also improve mechanical properties of the PU sponge. The sponges maintain the superhydrophobicity even when they are stretched with 200% strain or compressed with 50% strain. The sponges also show excellent mechanical stability, oil stability, and reusability in terms of superhydrophobicity and oil absorbency. The magnetic, durable, and superhydrophobic PU sponges are very promising materials for practical oil absorption and oil/water separation.Keywords: polyurethane sponges; silica; superoleophilic; surface chemistry; water purification
Co-reporter:Bin Mu, Wenbo Zhang, Weibing Xu, Aiqin Wang
Electrochimica Acta 2015 Volume 178() pp:709-720
Publication Date(Web):1 October 2015
DOI:10.1016/j.electacta.2015.08.091
•Hollowed-out tubular carbon@MnO2 composites were prepared derived from KF.•The morphology and electrochemical performance of composites can be facilely controlled.•The tubular structure and synergistic effect of hybrids enhance the electrochemical property.•The composites show good electrochemical performance in the testing temperature.•KF are expected to design other composites with the controlled tubular structure.The hollowed-out tubular carbon@MnO2 hybrid composites with hierarchical morphology have been successfully prepared via the redox reaction between MnO4− and tubular carbonized kapok fiber. The morphology and electrochemical performance of the as-prepared hybrid composites can be facilely controlled by adjusting the concentration of MnO4−. The carbon@MnO2 electrode with tubular structure of the assembled MnO2 nanosheets possess the highest specific capacitance of 321 F g−1 at a current density of 0.5 A g−1 with the capacitance retention of 94% at a scan rate of 100 mV s−1 for 800 cycles in 1.0 M Na2SO4 solution. The studies on the temperature dependence indicated that the specific capacitance increased with the increase in the testing temperature. The results reveal that the introduction of the highly conductive carbon in hybrid structure is one of the effective methods to improve the electrochemical performance of MnO2 electrodes whose poor conductivity limit their capacitance, cycling life and rate performance. It also can be concluded that it is crucial to design and control the morphology of materials in practical application for supercapacitor.
Co-reporter:Jie Tang, Bin Mu, Maosong Zheng, and Aiqin Wang
ACS Sustainable Chemistry & Engineering 2015 Volume 3(Issue 6) pp:1125
Publication Date(Web):April 17, 2015
DOI:10.1021/acssuschemeng.5b00040
Attapulgite/carbon nanocomposites were fabricated via one-step calcination of the spent bleaching earth served as adsorbents for the efficient removal of heavy metal ions (Cu(II), Pb(II) and Cd(II)). The as-prepared nanocomposites were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis and Brunauer–Emmett–Teller techniques. The process parameters affecting the adsorption behaviors such as initial pH, calcination temperature, contact time and initial concentration of heavy metal ions were systematically investigated. The results indicated that the attapulgite/carbon nanocomposites derived from the low-cost available carbon precursors exhibited high adsorption capacity within a wide pH range, and the faster equilibrium was achieved at lower concentration. In addition, the adsorbed Cu(II), Pb(II) and Cd(II) can be partially desorbed using 0.1 mol/L HCl as the desorbing agent, rendering the as-prepared adsorbent good readsorption ability, especially for the removal of Cu(II). Using the adsorption of Cd(II) as an example, it has been confirmed that the electrostatic interaction, cation exchange and surface complexation between Cd(II) and functional groups on the attapulgite/carbon nanocomposites were the dominant mechanisms according to the results of the adsorption studies and XPS analysis. Furthermore, this research develops a feasible route for the application of the spent bleaching earth in the wastewater treatment.Keywords: Adsorption; Attapulgite; Carbonization; Heavy metal ions; Spent bleaching earth;
Co-reporter:Yian Zheng, Aiqin Wang
European Polymer Journal 2015 Volume 72() pp:661-686
Publication Date(Web):November 2015
DOI:10.1016/j.eurpolymj.2015.02.031
•Four polymerization strategies for preparation of granular hydrogel are reviewed.•Potential of hydrogel as the adsorbent for pollutant removal is discussed.•Extensive literature information using this novel adsorbent is summarized.•Future perspectives in this direction are proposed.Hydrogels are 3D networks of polymer chains that are crosslinked via either physical or chemical bonds. A strong repulsive force is generated among those abundant functional groups with the same charge, which enables the hydrogels to be initially applied as the superabsorbent materials. Recent studies have found that the hydrogel adsorbents show superhigh adsorption capacities, fast adsorption rate, wide pH-independence, easy regeneration and reusable ability, by which the hydrogels are given the appellation “superadsorbent”. The limitations of traditional bulk hydrogel make granular hydrogel have received much attention in recent years. Therefore, the purpose of this review is to organize the scattered available information on the focus of polymerization strategies for the formation of granular hydrogels, with the scope limited to the crosslinked hydrogels via polymerization using one or more vinyl monomers. Furthermore, some of the important applications of hydrogel as the superadsorbents for removing various pollutants since 2000 are summarized and discussed, regardless of its form in either bulk or granular. An extensive list of hydrogel adsorbents has been compiled and selected studies with adsorption capacities for heavy metals including radioactive and rare earth metals, dyes and eutrophic substances as available in the literature are presented, with the key advancements of this type of novel adsorbents are briefly addressed. The facile synthesis and energy savings offer them a lot of promising benefits for commercial purposes in the future.Graphical abstract
Co-reporter:Yujie Zhang, Ling Fan, Hao Chen, Junping Zhang, Yuan Zhang, Aiqin Wang
Microporous and Mesoporous Materials 2015 Volume 211() pp:124-133
Publication Date(Web):15 July 2015
DOI:10.1016/j.micromeso.2015.03.002
•A facile method for preparing stable palygorskite/methylene blue@SiO2 (PAL/MB@SiO2) Maya Blue-like pigments.•The pigment shows excellent stability against elution, thermal aging and UV.•The MB content in the pigments can be as high as 12%.A facile method for the preparation of stable palygorskite/methylene blue@SiO2 (PAL/MB@SiO2) Maya Blue-like pigment was reported. The PAL/MB pigment was prepared via adsorption of MB by PAL, which was further coated with a layer of SiO2 by polycondensation of tetraethoxysilane (TEOS) with acetic acid (HAc) as the catalyst to form the PAL/MB@SiO2 pigment. The weight ratio of MB to PAL, ball milling time and heating temperature play important roles in affecting stability of the PAL/MB pigment. The MB content in the PAL/MB pigment is up to 12%, which is higher than all the state-of-the-art Maya Blue-like pigments. The MB molecules can only be adsorbed onto the external surface, the grooves and the openings of the channels of PAL, but cannot enter the channels according to the BET, zeta potential, FTIR and XRD analyses. Owing to the fact that the stability of the PAL/MB pigment is not very high, a layer of SiO2 is introduced to shield the MB molecules and further improve the stability. The PAL/MB@SiO2 pigment shows excellent stability against elution, thermal aging and intensive UV irradiation. A TEOS/HAc/H2O molar ratio of 1/2/140 in forming the SiO2 layer is greatly helpful to improve the stability.
Co-reporter:Wenbo Wang, Fangfang Wang, Yuru Kang, Aiqin Wang
Powder Technology 2015 Volume 269() pp:85-92
Publication Date(Web):January 2015
DOI:10.1016/j.powtec.2014.09.015
•High-pressure homogenization and phytic acid were used to disaggregate PAL bundles.•Nanoscale dispersion of palygorskite bundles was achieved by a one-step process.•The colloidal properties were sharply enhanced due to the nanoscale dispersion of PAL.•Phytic acid is favorable to disperse bundles and restrain the re-aggregation of rods.•The developed process is more suitable for the large-scale industrial production.The nanoscale dispersion of rod-like crystal bundles or aggregates of natural palygorskite (PAL) is not only significant in practical application but is also a challenge. In this paper, phytic acid (PA) was introduced during high-pressure homogenization (HPH) process to simultaneously disperse PAL crystal bundles and restrain the re-aggregation of the dispersed nanorods. SEM, TEM, XRD, FTIR and N2 adsorption–desorption analyses confirmed that the crystal bundles or aggregates of PAL were highly disaggregated and dispersed to individual nanorod with no disruption to the aspect ratio of rods after being homogenized at 30 MPa, and PA molecules are favorable to dispersion and restrain the re-aggregation of nanorods. The nanoscale dispersion of PAL rods increased the BET specific surface area and Zeta potentials, and effectively improved the colloidal properties. The colloidal viscosity of modified PAL was sharply increased by 110.4% (from 1728 mPa·s to 3636 mPa·s) at the optimal dosage of PA (0.1 wt.%) and the homogenization pressure of 30 MPa, and the suspension stability was clearly enhanced by 71%. This simple disaggregation process provides a new industrial approach to produce nanoscale PAL and extend its application in modern industry.
Co-reporter:Bin Mu, Qin Wang and Aiqin Wang
RSC Advances 2015 vol. 5(Issue 124) pp:102674-102681
Publication Date(Web):17 Nov 2015
DOI:10.1039/C5RA19955G
Clay/CoAl2O4 hybrid pigments with different morphologies and colors have been successfully fabricated by combining the coprecipitation technique and a successive calcination step. The morphologies of the obtained hybrid pigments are dependent on the morphologies of the inorganic clays, whereas the colors of the hybrid pigments are largely determined by the successive calcination temperature. The results reveal that the incorporation of the two-dimensional illite–smectite mixed-layer clay is favorable for the protection of the morphologies of the hybrid pigments from the calcination temperature compared with that of one-dimensional attapulgite. The color of the hybrid pigments changes from atrovirens to blue to dark blue with increasing calcination temperature from 800 °C to 1000 °C to 1200 °C, which is similar to the famous “Maya blue” pigment. It can be noted that the introduction of the inorganic clays not only decreases the production cost, but also prevents aggregation and an increase in the size of CoAl2O4 nanoparticles. There is no doubt that this strategy can realize the widespread application of CoAl2O4 pigments in the relevant fields.
Co-reporter:Zhifang Zhang, Wenbo Wang, Yuru Kang, Li Zong and Aiqin Wang
RSC Advances 2015 vol. 5(Issue 117) pp:96829-96839
Publication Date(Web):28 Oct 2015
DOI:10.1039/C5RA17724C
As the materials of “green 21st century material worlds”, natural silicates have received unprecedented attention by virtue of their abundance, low-cost, stability, and non-toxic and eco-friendly nature compared to other synthetic materials. With the aim to develop a new hybrid silicate adsorbent with improved adsorption properties, the naturally abundant palygorskite (PAL) was functionalized with glycine (GLY) via a simple one-step hydrothermal process and used for capturing Pb(II) ions from aqueous solution. The main reaction parameters, e.g., the pH values of the reaction medium, solid-to-liquid ratio, reaction time and dosage of GLY, were systematically optimized, and the as-prepared adsorbent was characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmittance electronic microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) techniques. The results reveal that the PAL crystal was converted to a hybrid silicate material with the assistance of GLY, and simultaneously the functional groups were introduced during the hydrothermal reaction, which caused an evident enhancement in the adsorption capacity of PAL for Pb(II) ions from 55.76 mg g−1 to 123.24 mg g−1. Almost 99.60% of Pb(II) could be captured and removed from a 40 mg L−1 Pb(II) solution using the as-prepared GLY-PAL silicate adsorbent, which is obviously higher than the 83.85% achieved by raw PAL. The intensified complexation of the functional groups on the silicate with Pb(II), the electrostatic attraction and the pore adsorption are responsible for the enhancement in the adsorption capability.
Co-reporter:Weibing Xu, Bin Mu, Wenbo Zhang and Aiqin Wang
RSC Advances 2015 vol. 5(Issue 79) pp:64065-64075
Publication Date(Web):20 Jul 2015
DOI:10.1039/C5RA13602D
Kapok fiber/MnO2 (TKF/MnO2) composites with a tubular structure are successfully fabricated via a facile hydrothermal process. Potassium permanganate and kapok fiber served as the manganese source and the template, respectively. The effects of operating parameters including material proportion, reaction temperature, reaction time and the growth mechanism of MnO2 are studied in detail. A maximum specific capacitance of 117 F g−1 has been achieved at 0.25 A g−1 in 1 M Na2SO4 and 95% specific capacitance is maintained after 1000 cycles, which demonstrates the potential application of tubular TKF/MnO2 composites in supercapacitors. The superior electrochemical performances of the obtained composites are attributed to their hollow structure, thin wall thickness, and orderly pore passages, which can facilitate ion diffusion and improve the utilization of the electroactive sites of MnO2.
Co-reporter:Wenbo Wang, Zhifang Zhang, Guangyan Tian and Aiqin Wang
RSC Advances 2015 vol. 5(Issue 72) pp:58107-58115
Publication Date(Web):22 Jun 2015
DOI:10.1039/C5RA05187H
The structural evolution of silicate opens a new avenue to cognize its microstructure, intensify its properties and extend its application. Herein, the one-step transformation of palygorskite (PAL) nanorods into smectite nanosheets was successfully achieved under mild hydrothermal condition with no addition of any extra chemicals. The structural evolution of PAL at different reaction stages and the change in physico-chemical characteristics was intensively studied through field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetry (TG) and Fourier transform infrared spectroscopy (FTIR) techniques. The key factors determining the transformation process were clarified. It was found that the moderate mechanical grinding, pH values and the existence of dolomite are essential to realize the transformation, and alkaline condition may facilitate the transformation. The transformation from nanorods to nanosheets is a rebuilding process of crystals, and the c/2 slide of tetrahedrons represents the main transformation mechanism. After the hydrothermal process, the adsorption capability of RPAL for Cu(II) evidently enhanced by 167%, and 99.01% of Cu(II) ions (only 64.9% for raw PAL) can be removed from 20 mg L−1 of Cu(II) solution.
Co-reporter:Jie Tang, Bin Mu, Li Zong, Maosong Zheng and Aiqin Wang
RSC Advances 2015 vol. 5(Issue 48) pp:38443-38451
Publication Date(Web):01 Apr 2015
DOI:10.1039/C5RA02497H
In this work, one-dimensional attapulgite/carbon composites were prepared by a one-step carbonization process using the residual organic matter of spent bleaching earth as a low-cost available carbon precursor. The obtained composites were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis to confirm the presence of carbonaceous species. The attapulgite/carbon composites can be used as adsorbents for the removal of methylene blue, with a maximum adsorption capacity of 132.72 mg g−1, and the process parameters affecting the adsorption behavior for methylene blue, such as the pH of the solution, calcination temperature and contact time, were also analyzed through batch adsorption processes. It was revealed that attapulgite/carbon composites could be employed as candidates for the removal of cationic dyes.
Co-reporter:Yujie Zhang, Ling Fan, Junping Zhang and Aiqin Wang
RSC Advances 2015 vol. 5(Issue 44) pp:35010-35016
Publication Date(Web):10 Apr 2015
DOI:10.1039/C5RA01863C
Poor water-dispersibility and stability of hydrophobic fluorescent organic pigments (HFOPs) hinder many of their applications. Inspired by the excellent stability of Maya Blue pigments and the water solubility of LAPONITE® RD (LRD), we report the facile synthesis of water-dispersible and stable fluorescent Maya Blue-like pigments via the host–guest interaction between LRD and Pigment Red 31 (PR 31), a representative HFOP. The concentration of LRD and solid-state grinding play important roles in effectively dispersing PR 31 into the aqueous solution. The interactions between PR 31 and LRD involve van der Waals, π–π, electrostatic, hydrogen bonding between phenolic hydroxyl groups of PR 31 and silanols of LRD as well as dye–dye hydrophobic interactions. The interactions between PR 31 and LRD occur on the external surface of LRD and the entrance of the micropores of LRD, however, the PR 31 molecules cannot intercalate into the layers of LRD plates. The so-obtained pigments are highly water-dispersible, and very stable to thermal aging and UV irradiation owing to the interactions between LRD and PR 31, and the shielding effect of LRD.
Co-reporter:Hailin Lu, Wenbo Wang and Aiqin Wang
RSC Advances 2015 vol. 5(Issue 23) pp:17775-17781
Publication Date(Web):26 Jan 2015
DOI:10.1039/C4RA09835H
Chitosan/poly(vinyl alcohol) (CS/PVA) films have recently attracted considerable attention. However, CS/PVA film has a significant flaw. It may swell in an aqueous solution and then lose its mechanical strength. Many efforts have been engaged to strengthen the CS/PVA film by adding various reinforcing materials, but the effect of different post-processing methods on the crystallization and mechanical behaviors of the film was rarely investigated. In this study, we have introduced natural nanoscale attapulgite (APT) into CS/PVA film to enhance its mechanical properties. Based on this, the resultant CS/PVA/APT nanocomposite film was further treated with a solution of NaOH and ethanol to regulate the crystallization degree of the polymer chains. The results reveal that the APT nanorods that are uniformly dispersed in the CS/PVA matrix can form a stronger hydrogen-bonding network with the polymer chains to improve the thermal stability and tensile strength. After treatment with NaOH and ethanol, the crystallization degree of the nanocomposite film was greatly enhanced, which caused an evident improvement in its mechanical properties. This method provides a simple and green approach to enhance the mechanical properties of polymer-based films.
Co-reporter:Zhifang Zhang, Wenbo Wang, Aiqin Wang
Applied Surface Science 2015 Volume 329() pp:306-314
Publication Date(Web):28 February 2015
DOI:10.1016/j.apsusc.2014.12.187
Highlights
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Palygorskite was modified by a homogenization associated hydrothermal process.
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The crystal bundles of PAL were disaggregated efficiently after modification.
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The adsorption of palygorskite for Methylene blue was greatly enhanced.
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MB-loaded palygorskite exhibits excellent resistance to acid and alkali solution.
Co-reporter:Yian Zheng;Yongfeng Zhu;Feng Wang;Aiqin Wang
Water, Air, & Soil Pollution 2015 Volume 226( Issue 10) pp:
Publication Date(Web):2015 October
DOI:10.1007/s11270-015-2624-y
Featured with biodegradability and biocompatibility properties, gelatin (GE) was selected as the backbone to graft poly(acrylic acid) (PAA) to fabricate a granular hydrogel at room temperature in air. Using attapulgite (APT) as an inorganic component, the resulting GE-g-PAA/APT hydrogel was characterized by means of Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and zeta potential analysis and then used as the adsorbent to be applied in a mixed dye solution containing malachite green and orange G. The addition of APT can significantly reduce the swelling degree during the adsorption process, though its influences on the adsorption capacity are not so expectable. The as-prepared hydrogel shows a wide pH-independent adsorption from 3.0 to 10.0, with the maximum adsorption capacity of 1370 mg/g for GE-g-PAA and 1190 mg/g for GE-g-PAA/APT (5 wt%). More importantly, the as-prepared hydrogel shows high adsorption selectivity for cationic dyes and the dye-loaded hydrogel can be easily regenerated and recovered for successive adsorption cycles.
Co-reporter:Wenbo Wang;Fangfang Wang;Yuru Kang;Aiqin Wang
Water, Air, & Soil Pollution 2015 Volume 226( Issue 3) pp:
Publication Date(Web):2015 March
DOI:10.1007/s11270-015-2355-0
Silicate clay materials are promising natural adsorbents with abundant, low cost, stable, and eco-friendly advantages, but the limited adsorption capacity restricts their applications in many fields. Herein, palygorskite (PAL) was facilely activated with alkali to enhance its adsorptive removal capability for methylene blue (MB). The effects of alkali activation on the microstructure, physicochemical, and adsorption properties of PAL for MB were intensively investigated. It was found that the moderate alkali activation can partially remove the metal cations (i.e., Al3+, Mg2+) and Si in the crystal backbone of PAL by which new “adsorption sites” were created and the surface negative charges increased. The adsorption capacity and rate of PAL for MB were evidently enhanced due to the effective activation. The adsorption isotherms were described by Freundlich isotherm model very well, and the adsorption kinetics can be accurately presented by a pseudo-second-order model. It can be inferred from the fitting results that the overall adsorption process was controlled by external mass transfer and intra-particle diffusion (the dominant role). The multiple adsorption interactions (hydrogen bonding, electrostatic interactions, mesopore filling, and complexing) were turned out to be the dominant factors to improve the adsorption properties. It was revealed that the activated PAL could be used as a potential adsorption candidate for environmental applications.
Co-reporter:Wenbo Zhang;Bin Mu;Aiqin Wang
Journal of Solid State Electrochemistry 2015 Volume 19( Issue 5) pp:1257-1263
Publication Date(Web):2015 May
DOI:10.1007/s10008-014-2730-6
Halloysite nanotubes@carbon/manganese dioxide nanocomposites (HNTs@C/MnO2) with coaxial tubular structure were prepared by introducing manganese dioxide on the surface of carbon-coated halloysite nanotubes (HNTs@C). The HNTs@C nanocomposites were synthesized by hydrothermal carbonization of glucose on the surface of HNTs and further activated at high temperature to improve the degree of carbonization. The use of halloysite nanotubes can effectively induce the heterogeneous deposition of carbonaceous species on the surface of the halloysite nanotubes, and then uniformly generate MnO2 nanoflakes via the redox reaction between the carbon and potassium permanganate to construct the hybrid coaxial structure. The as-prepared hybrid materials were characterized by transmission electron microscope, Fourier transform infrared spectrum, X-ray diffraction, and thermogravimetric analysis. The specific capacitance of HNTs@C/MnO23 nanocomposites can reach 274 F g−1 at 1.25 mA cm−2 in 1.0 M Na2SO4 electrolyte after correcting the weight percent of electroactive materials. Furthermore, the special coaxial tubular structure and the manganese dioxide nanoflakes facilitated the ion diffusion between the electrode/electrolyte interfaces. The results indicate that the novel coaxial tubular hybrid nanocomposites can be a promising candidate as electrode material for supercapacitors.
Co-reporter:Lei Wu, Junping Zhang, Bucheng Li, Ling Fan, Lingxiao Li, Aiqin Wang
Journal of Colloid and Interface Science 2014 Volume 432() pp:31-42
Publication Date(Web):15 October 2014
DOI:10.1016/j.jcis.2014.06.046
•A facile approach for preparing super durable superhydrophobic materials.•The materials exhibit excellent mechanical and chemical stabilities.•The superhydrophobic materials can be used for effective oil/water separation.The low stability, complicated and expensive fabrication procedures seriously hinder practical applications of superhydrophobic materials. Here we report an extremely simple method for preparing super durable superhydrophobic materials, e.g., textiles and sponges, by dip coating in fluoropolymers (FPs). The morphology, surface chemical composition, mechanical, chemical and environmental stabilities of the superhydrophobic textiles were investigated. The results show how simple the preparation of super durable superhydrophobic textiles can be! The superhydrophobic textiles outperform their natural counterparts and most of the state-of-the-art synthetic superhydrophobic materials in stability. The intensive mechanical abrasion, long time immersion in various liquids and repeated washing have no obvious influence on the superhydrophobicity. Water drops are spherical in shape on the samples and could easily roll off after these harsh stability tests. In addition, this simple dip coating approach is applicable to various synthetic and natural textiles and can be easily scaled up. Furthermore, the results prove that a two-tier roughness is helpful but not essential with regard to the creation of super durable superhydrophobic textiles. The combination of microscale roughness of textiles and materials with very low surface tension is enough to form super durable superhydrophobic textiles. According to the same procedure, superhydrophobic polyurethane sponges can be prepared, which show high oil absorbency, oil/water separation efficiency and stability.Graphical abstract
Co-reporter:Bin Mu, Wenbo Zhang, Shijun Shao and Aiqin Wang
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 17) pp:7872-7880
Publication Date(Web):27 Feb 2014
DOI:10.1039/C4CP00280F
The graphene–MnO2–polyaniline (rGO–MnO2–PAn) ternary composites were prepared via in situ chemical oxidative polymerization of polyaniline on the MnO2 decorated graphene sheets. The graphene sheets were treated with KMnO4 in a water–ethylene glycol system using the hydrothermal method to complete the loading of MnO2 on the graphene sheets, while the graphene oxide (GO) sheets were hydrothermally reduced to reduced graphene oxide (rGO). The glycol was introduced as a reductant to react with MnO4−, and GO was protected from consumption in the process of deposition of MnO2. The structures and morphologies of the resulting ternary composites are characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of the composites as potential electrode materials for supercapacitors were investigated using different electrochemical techniques including cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS). The specific capacitance of a rGO–MnO2–PAn composite electrode was 395 F g−1 at 10 mA cm−2 in 1 M H2SO4 solution. The composites displayed good cycle stability retaining 92% of their original specific capacitance after 1200 cycles by continuous cyclic voltammetric scans at 100 mV s−1.
Co-reporter:Xiaoning Shi, Wenbo Wang, Yian Zheng and Aiqin Wang
RSC Advances 2014 vol. 4(Issue 92) pp:50478-50485
Publication Date(Web):24 Sep 2014
DOI:10.1039/C4RA10866C
A pretreated kapok fiber (PKF) with a hollow tube structure was introduced into a poly(sodium acrylate) network by a simultaneous free-radical graft copolymerization and crosslinking reaction to fabricate a novel kapok fiber-g-poly(sodium acrylate) (PNaA/PKF) superabsorbent composite. The network characteristics and surface morphologies of the PNaA/PKF superabsorbent composite were investigated by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), as well as by determination of mechanical properties, swelling and stimuli responses to salts, and pH. The results showed that the incorporation of a specific amount of PKF not only improved the water absorption, but also the gel content and gel strength. The composite with 10 wt% PKF showed the best water absorption, gel content and gel strength. The swelling kinetics of the composite followed Schott's pseudo-second-order kinetics model, and the swelling rate constant was enhanced 2.63 fold after adding 10 wt% PKF. The swelling and deswelling behaviors in various saline and pH solutions revealed the stimuli-sensitivity of the PNaA/PKF composite to salt concentration, ionic charge and external pH, and a remarkable time-dependent swelling process with an overshooting characteristic was observed in pH 2 solutions.
Co-reporter:Jixiang Xu, Wenbo Wang, Aiqin Wang
Powder Technology 2014 Volume 261() pp:98-104
Publication Date(Web):July 2014
DOI:10.1016/j.powtec.2014.04.018
•Aggregates of palygorskite were well disaggregated by high-pressure homogenization.•Introduction of ethanol enhanced the disaggregation efficiency of palygorskite.•The 6:4 ethanol-water mixture induced the best dispersion of rods of palygorskite.•Mechanism is that ethanol may greatly weaken the interaction among rods than water.The nanorods of natural palygorskite exist as aggregates or bundles. High-pressure homogenization technology can disaggregate effectively the bundles or aggregates of palygorskite in water. In order to further explore the effect of the dispersion medium on the dispersion efficiency, in this paper, palygorskite was dispersed in ethanol–water mixture with the aid of high-pressure homogenization. The effects of various ethanol/water ratios on the microstructure and colloidal properties of palygorskite were investigated. It was found that the dispersion efficiency of aggregates during the homogenization process was affected as increasing the ethanol/water ratio from 0:10 to 4:6. The introduction of ethanol into the aqueous suspension of palygorskite could weaken the van der Waals forces and hydrogen bonding interaction among rods, and a stable suspension with higher shear stress and shear modulus was obtained at the ethanol/water ratio of 6:4 (v/v).The ethanol/water mixtures are more effective to the disaggregation of crystal bundles and aggregates of natural palygorskite as individual nanorods via high-pressure homogenization process.
Co-reporter:Bin Mu, Wenbo Wang, Junping Zhang and Aiqin Wang
RSC Advances 2014 vol. 4(Issue 74) pp:39439-39445
Publication Date(Web):18 Aug 2014
DOI:10.1039/C4RA05892E
Superparamagnetic sandwich structured silver/halloysite nanotube/Fe3O4 (Ag/HNT/Fe3O4) nanocomposites were fabricated by selective modification of the lumen of halloysite nanotubes with silver nanorods and the external wall with Fe3O4 nanoparticles. The silver nanorods within the lumen of halloysite nanotubes and the uniform Fe3O4 shell on the external wall were confirmed by transmission electron microscopy. The Ag/HNTs/Fe3O4 nanocomposites exhibit excellent catalytic activity and recyclability for the reduction of 4-nitrophenol to 4-aminophenol by NaBH4. In addition, the nanocomposites show high efficiency in magnetic separation due to the high saturation magnetization and superparamagnetism. Therefore, the nanocomposites have great potential application in the catalytic field as recyclable and low-cost catalysts.
Co-reporter:Jixiang Xu, Wenbo Wang, Aiqin Wang
Advanced Powder Technology 2014 Volume 25(Issue 3) pp:968-977
Publication Date(Web):May 2014
DOI:10.1016/j.apt.2014.01.019
Highlights
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Effect of mechanical treatment on rheological properties of palygorskite was studied.
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Squeeze, homogenization and freezing methods were employed to disperse palygorskite.
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Yield stress, shear modulus and association degree of suspensions were evaluated.
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Colloidal properties are related to dispersion and disruption of palygorskite rods.
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Strongly associated system is got by squeeze for 3 times and homogenization at 30 MPa.
Co-reporter:Wenbo Zhang, Bin Mu, Aiqin Wang, Shijun Shao
Synthetic Metals 2014 Volume 192() pp:87-92
Publication Date(Web):June 2014
DOI:10.1016/j.synthmet.2014.03.021
•A novel APT@C/PAn hybrid nanocomposite was prepared using APT as matrix.•APT can guide the deposition of carbon and prevent PAn from aggregation.•The specific capacitance of APT@C@PAn electrode materials reached 324.5 F g−1.Attapulgite@carbon/polyaniline (APT@C/PAn) hybrid nanocomposites were fabricated by in situ chemical oxidative polymerization of aniline after hydrothermal carbonization of glucose on the surface of the attapulgite. The introduction of attapulgite can effectively guide the heterogeneous deposition of carbonaceous species on the surface of attapulgite and further prevent polyaniline from self-aggregation. The obtained hybrid nanocomposites were characterized by transmission electron microscope, Fourier transform infrared spectrum, X-ray diffraction, and thermogravimetric analysis. The maximum specific capacitance of the APT@C/PAn electrode materials was 324.5 F g−1 after correcting for the weight percent of the electroactive materials at a current density of 2.5 mA cm−2 in a 1.0 M H2SO4 electrolyte. The excellent performance might be ascribed to the orientation of APT and the combination of the good electrical conductivity of carbon and the pesudocapacitance of polyaniline.
Co-reporter:Wenbo Wang;Yuru Kang;Aiqin Wang
Journal of Nanoparticle Research 2014 Volume 16( Issue 2) pp:
Publication Date(Web):2014 February
DOI:10.1007/s11051-014-2281-x
A facile solvents-free reaction method was employed to in situ prepare Ag nanoparticles/attapulgite (Ag-NPs/APT) nanocomposites and used for the catalytic reducing decoloration of Congo red (CR) dye. The Ag-NPs with different sizes and loading amounts were in situ formed by the thermal decomposition of silver acetate with no need of any chemical solvent, reductant, stabilizer, or electric current; and the formed Ag-NPs were uniformly immobilized on APT as shown by X-ray diffraction and transmission electron microscopy analyses. The nanocomposites show excellent catalytic activity to catalytic reducing CR dye in the presence of NaBH4, and the CR solution (20 mg/L) can be rapidly decolored within 2 min at the lower dosage of nanocomposite (0.3 g/L). The electron transfer from BH4− to the electron acceptor CR, mediated by Ag-NPs, represents the main reduction mechanism. The nanocomposite still shows better catalytic activity after ten cycles, hence it can be used as a recycle material for catalytic applications.
Co-reporter:Yian Zheng, Yongfeng Zhu, Aiqin Wang
Polymer 2014 Volume 55(Issue 20) pp:5211-5217
Publication Date(Web):26 September 2014
DOI:10.1016/j.polymer.2014.08.040
•Kapok fiber structure-oriented polyallylthiourea (KF-PAT) was in situ prepared.•KF-PAT showed efficient adsorptive reduction for Au(III) in aqueous solution.•Conversion of Au(III) into Au NPs was achieved without any external assistance.•Au NPs-loaded KF-PAT is an efficient catalyst for the reduction of 4-nitrophenol.In this study, kapok fiber structure-oriented polyallylthiourea (KF-PAT) has been approached via a facile in situ preparation and then used as the adsorbent to entrap Au(III) ions in aqueous solution. During this process, an efficient adsorptive reduction with the conversion of Au(III) into metallic Au nanoparticles (NPs) was observed using KF-PAT as the adsorbent. This conclusion was successfully confirmed by means of X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS). The conversion of Au(III) ions into Au NPs was achieved without the assistance of any external reducing agents and the resulting Au NPs were uniformly dispersed into the polymer matrix, as supported by the observation from transmission electron microscopy (TEM). Finally, the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with an excess amount of NaBH4 was used as a model reaction to evaluate the catalytic performance of Au NPs-loaded KF-PAT.
Co-reporter:Bin Mu, Qin Wang and Aiqin Wang
Journal of Materials Chemistry A 2013 vol. 1(Issue 24) pp:7083-7090
Publication Date(Web):10 May 2013
DOI:10.1039/C3TA10658F
A magnetic attapulgite nanocomposite grafted crosslinked copolymer (CPSA@MATP) has been prepared via a “grafting from” technique for the adsorption of Ag+. The results show that the adsorption rate reaches 95% at pH 3 and 80% at 1% NaCl with a 1 mg mL−1 initial concentration of Ag+, respectively. The subsequent treatment of Ag+-loaded CPSA@MATP with NaBH4 leads to chemical reduction of the Ag+ to obtain Ag nanoparticle decorated CPSA@MATP (CPSA@MATP/AgNP). The catalytic activity of the CPSA@MATP/AgNP nanocomposite for the reduction of 4-nitrophenol with NaBH4 is tracked by UV-vis spectroscopy. It is suggested that CPSA@MATP/AgNP exhibits excellent catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by NaBH4. Furthermore, MATP@CPSA/AgNP can be easily recycled due to its magnetism. Therefore, the CPSA@MATP nanocomposite has a great potential application in the adsorption of trace precious metal ions, and further can be used as recyclable and low-cost catalytic materials in the area of catalytic reduction due to the high catalytic activity of precious metal nanoparticles and the superparamagnetism of Fe3O4 in the future.
Co-reporter:Bin Mu, Yuru Kang and Aiqin Wang
Journal of Materials Chemistry A 2013 vol. 1(Issue 15) pp:4804-4811
Publication Date(Web):11 Feb 2013
DOI:10.1039/C3TA01620J
By the layer-by-layer self-assembly of chitosan and cysteine modified β-cyclodextrin on the surface of Fe3O4 nanoparticle-decorated attapulgite, the polyelectrolyte-coated magnetic attapulgite composite (Fe3O4/ATP@(CS/Cys-β-CD)8) was prepared for the adsorption of precious metals. The as-synthesized Fe3O4/ATP@(CS/Cys-β-CD)8 composite was characterized by zeta potential measurements, Fourier transform infrared spectroscopy, X-ray diffraction and vibrating sample magnetometry. The Fe3O4/ATP@(CS/Cys-β-CD)8 composite has an adsorption yield of about 90% for Ag+, 90% for Pd2+ and 60% for Pt4+. Moreover, it was found that the adsorption of Ag+ and Pd2+ was preferential to that of Pt4+. The results of X-ray photoelectron spectroscopy indicated that the precious metals accept electrons provided by the N, O or S atoms of the Fe3O4/ATP@(CS/Cys-β-CD)8 composite during the process of adsorption. Therefore, the Fe3O4/ATP@(CS/Cys-β-CD)8 composite is a promising recyclable and low-cost adsorbent for the adsorption of trace precious metal ions.
Co-reporter:Bin Mu, Peng Liu, Aiqin Wang
Electrochimica Acta 2013 Volume 88() pp:177-183
Publication Date(Web):15 January 2013
DOI:10.1016/j.electacta.2012.10.025
The polyaniline (PAn)/carbon black (CB) hybrid hollow microspheres have been prepared by the layer-by-layer assembly technique alternately adsorbing of PAn and CB onto the polystyrene sulfonate microsphere templates after etching the templates by dialysis. The hollow structure of the obtained hybrid hollow microspheres was characterized by transmission electron microscopy, which indicated that the external diameter of the hollow microspheres was about 3.0 μm. When the hybrid hollow microsphere were used as the electrode material for supercapacitors, the results showed that the specific capacitance increased with the increase in the adsorption numbers of PAn and CB, which was as high as 532 F g−1 at a charge–discharge current density of 10 mA cm−2 in 1.0 M H2SO4 electrolyte after alternately adsorbing of PAn and CB six times.Graphical abstractThe polyaniline/carbon black hybrid hollow microspheres with a external diameter about 3.0 μm were prepared via layer-by-layer assembly technique, and the electrochemical tests showed that polyaniline/carbon black hybrid hollow microspheres would be a potential candidates of electrode materials for supercapacitors with high specific capacitance.Highlights► The PAn/CB hybrid hollow microspheres were prepared via LBL technique. ► The specific capacitance increased with the increase in the adsorption of PAn and CB. ► The hollow structure and synergistic effect of shell enhance the specific capacitance. ► The PAn/CB hollow microsphere is a candidate of electrode material for supercapacitor.
Co-reporter:Xiaoning Shi, Wenbo Wang, Aiqin Wang
Carbohydrate Polymers 2013 Volume 94(Issue 1) pp:449-455
Publication Date(Web):15 April 2013
DOI:10.1016/j.carbpol.2013.01.019
A novel sodium alginate-based superporous hydrogel (SPH) was prepared by the grafting copolymerization and micelle templating formed by the self-assembled anionic surfactant sodium n-dodecyl sulfonate (SDS). Fourier transform infrared (FTIR) spectra demonstrated that SDS was removed from the final hydrogel network. The formation mechanism of NaAlg-based SPH was proposed. Effect of SDS concentration on the morphologies and pore structure of the hydrogel was evaluated by Scanning Electron Microscopy (SEM), and the SDS-1.92 mM sample displays homogeneous and well-defined pores, which contribute to improve swelling ratio and swelling rate. The time-dependent swelling behaviors of the SDS-1.92 mM samples in various salt and pH solutions were investigated. The swelling in multivalent salt (Ca2+, Al3+)/pH 2 solutions displayed a well-known “overshooting effect”, whereas, its swelling kinetics in Na+/pH 3–12 solutions followed Schott's pseudo second-order swelling kinetics model.Highlights► Superporous NaAlg-based hydrogel was prepared by the self-assembling micelle templating. ► FTIR spectra demonstrated that the removing of micelle from the final hydrogel network. ► The morphology and porous structure of the hydrogel was evaluated by SEM. ► The surfactant micelle templating is an efficient technique to produce superporous hydrogel.
Co-reporter:Yian Zheng, Wenbo Wang, Gong Zhu, and Aiqin Wang
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 13) pp:4957
Publication Date(Web):March 19, 2013
DOI:10.1021/ie302562f
With Fenton’s reagent as the redox initiator, a granular hydrogel was prepared under ambient conditions, and then modified with polyaniline (PAN) to develop a composite adsorbent with enhanced adsorption selectivity for the heavy metals, such as the Cu–Ni system in this study. The results indicate that PAN-modified hydrogel shows decreasing adsorption kinetics, but with a comparable adsorption capacity for Cu(II). Moreover, the adsorption selectivity for Cu(II) exhibits an impressive improvement, with the selectivity coefficient (KCu–Ni) being enhanced by a factor of 6–7 (aniline:hydrogel = 1:20) for binary Cu–Ni and quaternary Cu–Ni–Cr–Zn systems. Finally, the adsorption and desorption characteristics were evaluated during multicycle adsorption processes.
Co-reporter:Jixiang Xu, Wenbo Wang, Aiqin Wang
Powder Technology 2013 Volume 249() pp:157-162
Publication Date(Web):November 2013
DOI:10.1016/j.powtec.2013.08.002
•Freeze combined with extrusion and homogenization was used to treat palygorskite.•The treated palygorskite retained its rod-like crystals structure.•The desirable disaggregation efficiency was achieved by controlling freezing time.•The suspension viscosity enhanced about 2.0 times as compared to unfroze sample.Palygorskite is a natural nanorod with about 20–70 nm in diameter and 1–2 μm in length, but the intrinsic existence form of palygorskite as aggregates or bundles effaces its nanometer characteristic. In this work, a novel method for effective disaggregation of crystal bundles of palygorskite was developed via freezing assisted extrusion and homogenization process. The effects of freezing process and freezing time on the disaggregation state, micro-structure and properties of treated palygorskite were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (IR), X-ray diffraction (XRD), N2 adsorption–desorption isotherm (BET), and rotary viscosity measurements. The dispersion of palygorskite depended greatly on freezing time, and a highly dispersed palygorskite nanorods were achieved after freezing for 4 h followed by homogenization at 10 MPa. The treated palygorskite retained its original structure, and the rods were rarely disrupted. The specific surface area of palygorskite enhanced from 163 m2/g to 237 m2/g as the freezing time increased from 0 to 8 h, and the rotary viscosity increased from 152 mPa·s of natural palygorskite to 2682 mPa·s, which was about 2.0 folds of the sample without freezing treatment.The freeze combined with extrusion and homogenization treatment can disaggregate the crystal bundles of palygorskite and highly dispersed palygorskite rods were achieved by controlling freezing time. The viscosity of the suspension with a maximum of 2682 mPa·s was obtained after freezing for 8 h.
Co-reporter:Jixiang Xu, Wenbo Wang, Aiqin Wang
Powder Technology 2013 Volume 235() pp:652-660
Publication Date(Web):February 2013
DOI:10.1016/j.powtec.2012.11.035
Dispersion of natural palygorskite in distilled water, methanol, ethanol, isopropanol, dimethyl formamide, and dimethyl sulfoxide was carried out using high-pressure homogenization. The effects of solvent parameters on the microstructure, morphology and colloidal properties of palygorskite were investigated in detail. Elemental analysis, infrared spectroscopy (IR) and thermogravimetric analysis (TGA) confirmed that some solvent molecules were encapsulated within the tunnels of palygorskite. The efficiency of the homogenization process to disperse palygorskite aggregates was closely correlated to the solvent parameters, particularly solvent vapor pressure and viscosity. A well disaggregated palygorskite was obtained after dispersing in dimethyl sulfoxide. It was also confirmed that colloidal stability and suspension viscosity were affected by the solvent nature. A more stable suspension with higher viscosity of 2364 mPa s was obtained by dispersing palygorskite in isopropanol.The homogenization treatment can disaggregate the crystal bundles of palygorskite in various solvents and highly dispersed palygorskite rods were achieved by dispersing in dimethyl sulfoxide. A stable suspension with higher viscosity was obtained by dispersing in isopropanol.Highlights► Homogenization treatment palygorskite suspension dispersed in various solvents. ► Solvent vapor pressure, viscosity and surface tension govern dispersion efficiency. ► Highly dispersed palygorskite rods were achieved by dispersing in dimethyl sulfoxide. ► Some solvents enter the tunnels of palygorskite and decrease its textural parameters. ► A stable suspension with higher viscosity was obtained by dispersing in isopropanol.
Co-reporter:Wenbo Wang, Fangfang Wang, Yuru Kang and Aiqin Wang
RSC Advances 2013 vol. 3(Issue 29) pp:11515-11520
Publication Date(Web):23 May 2013
DOI:10.1039/C3RA41836G
In this paper, we employed a simple and efficient electrostatic self-assembly strategy to fabricate superparamagnetic attapulgite/Fe3O4/Au nanoparticles (APT/Fe3O4/AuNPs) nanocomposites with a well-dispersed distribution of AuNPs using natural chitosan (CTS) as a “bridge”. The “toruloid” APT/Fe3O4 composite with negative surface charges was firstly prepared by a one-step solvent-thermal reaction between APT, FeCl3 and ethylene glycol, and then the positively charged CTS was used as a “double sided tape” to tightly adhere APT/Fe3O4 and AuNPs through electrostatic interaction. UV-vis, XRD and TEM analyses proved that the “toruloid” structure was formed, and AuNPs were successfully attached on the APT surface with good dispersion. The formation of the “toruloid” composite structure can not only bring stronger magnetism, but also facilitate the attachment of AuNPs. The APT/Fe3O4/AuNPs nanocomposite shows excellent catalytic activity, which can rapidly catalytically decolor a solution of Congo red (20 mg L−1) within 2 min at a low dosage of 0.3 g L−1. In addition, the nanocomposite shows strong magnetism with a maximum magnetization rate of 33.6 emu g−1. This makes the nanocomposite prone to be magnetically separated and recycled.
Co-reporter:Dajian Huang and Aiqin Wang
RSC Advances 2013 vol. 3(Issue 4) pp:1210-1216
Publication Date(Web):21 Nov 2012
DOI:10.1039/C2RA22016D
Multiwalled carbon nanotubes (MWCNTs) were regarded as ideal candidates for fillers in a polymer matrix due to their outstanding mechanical, electrical and thermal properties. A series of nanocomposite films were prepared by a solution casting method introducing chitosan (CS) treated MWCNTs into a poly (vinyl alcohol) (PVA) matrix. The nanocomposites were characterized by field emission scanning electron microscopy and Fourier Transform Infrared Spectroscopy. The results indicated that MWCNTs treated by chitosan dispersed well in the PVA matrix, and the tensile properties and water resistance of nanocomposites were improved greatly compared with neat PVA.
Co-reporter:Jintao Wang;Yian Zheng;Aiqin Wang
Journal of Applied Polymer Science 2013 Volume 127( Issue 3) pp:2184-2191
Publication Date(Web):
DOI:10.1002/app.37783
Abstract
In this work, a series of polybutylmethacrylate/kapok fiber (PBMA/KF) composites were synthesized by suspended emulsion polymerization and well characterized by means of Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The effects of reaction parameters, such as amount of initiator, crosslinker, emulsifier, KF content on oil absorbency, were investigated in detail. The optimum polymerization conditions were obtained as initiator of 0.4 wt %, crosslinker of 1.0 wt %, emulsifier of 2.0 wt %, and KF content of 8.0 wt %. Compared with PBMA, the as-prepared PBMA/KF (8 wt % KF) showed better oil sorption capacity, with the increase percentage of 58.7% in toluene and 66.7% in chloroform. Swelling behavior indicated that the sorption equilibrium was established basically within 15 min, and the incorporation of KF can promote the oil sorption rate. Furthermore, the composite exhibited better reusability and oil retention capabilities, and can be recognized as a kind of low-cost oil sorption materials for oil pollution treatment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Yizhe Wang;Xiaoning Shi;Wenbo Wang;Aiqin Wang
Journal of Applied Polymer Science 2013 Volume 129( Issue 3) pp:1080-1088
Publication Date(Web):
DOI:10.1002/app.38786
Abstract
The dispersion of attapulgite (APT) as nanorod-like single crystals is crucial to fully develop its functionality of one-dimensional nanometer material as a filler of composite materials. In this study, APT was dispersed by the assistance of ethanol during the high-pressure homogenization process to form individual nanorod-like crystals. The dispersed APT was used to prepare new sodium alginate-g-poly(sodium acrylate-co-styrene)/attapulgite (NaAlg-g-P(NaA-co-St)/APT) superabsorbent nanocomposites. The effect of ethanol/water ratio on the dispersion of crystal bundles of APT was investigated by field emission scanning electron microscopy, and the results indicate that APT crystal bundles were effectively disaggregated in ν(CH3CH2OH) : ν(H2O) − 5 : 5 solution after homogenized at 50 MPa. The better dispersion of APT in NaAlg-g-P(NaA-co-St) matrix has clearly improved the gel strength (from 1300 Pa to 1410 Pa, ω = 100 rad/s), swelling capacity (442–521 g/g), swelling rate (3.3303–4.5736 g/g/s), and reswelling ability of the superabsorbent nanocomposite. Moreover, the nanocomposites showed fast swelling–deswelling responsive behavior in different saline solutions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Yizhe Wang;Wenbo Wang;Xiaoning Shi;Aiqin Wang
Journal of Applied Polymer Science 2013 Volume 130( Issue 1) pp:161-167
Publication Date(Web):
DOI:10.1002/app.39141
Abstract
A series of superabsorbent nanocomposites were prepared by free radical grafting copolymerization of sodium alginate, partially neutralized acrylic acid (AA), styrene, and illite/smectite mixed-layer clay (I/S). The structure and morphology of the nanocomposites were confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscope techniques. It was shown that the incorporation of I/S clearly enhanced the swelling properties of the nanocomposites. Various salts and surfactants showed remarkable effects on the swelling behaviors of the nanocomposites. Moreover, the nanocomposite exhibited better responsive and reversible on–off switching characteristics in pH 7.0 and 2.0 buffer solutions, which renders it promising for drug delivery application. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Jintao Wang;Qin Wang;Yian Zheng;Aiqin Wang
Polymer Composites 2013 Volume 34( Issue 2) pp:274-281
Publication Date(Web):
DOI:10.1002/pc.22414
Abstract
A series of polybutylmethacrylate/organo-attapulgite (PBMA/organo-APT) nanocomposites were prepared by suspended emulsion polymerization using ethylene glycol dimethacrylate (EGDMA) as a crosslinker, and organo-APT treated by different quaternary ammonium salt (C12, C16, and C18) as an inorganic component. The nanocomposites were characterized by means of Fourier transform infrared spectroscopy and scanning electron microscopy (SEM), showing that organo-APT participated in polymerization by which a nanocomposite structure was formed. The effects of crosslinker and organo-APT with different alkyl chain length on oil absorbency were investigated. The swelling kinetics in toluene, chloroform and gasoline were also systematically studied. The results reveal that introducing organo-APT with moderate hydrophobic-chain length into the PBMA polymeric network can improve oil absorption capability and swelling rate. POLYM. COMPOS., 2013 © 2013 Society of Plastics Engineers
Co-reporter:Jixiang Xu, Wenbo Wang, and Aiqin Wang
Journal of Chemical & Engineering Data 2013 Volume 58(Issue 3) pp:764-772
Publication Date(Web):February 12, 2013
DOI:10.1021/je301280u
A series of palygorskite samples modified with electrolytes including KCl, KBr, KI, KH2PO4, KHSO4, K2HPO4, K2SO4, and K3PO4 were prepared with the aid of high pressure homogenization. The changes of electrokinetic and rheological properties, as well as suspension stability of obtained palygorskite, were investigated through measurement of the zeta potential, flow curve, and sedimentation volume. The influences of charge, concentration, and type of anions on surface charge density of palygorskite were compared. The correlation among the surface charge, the rheological behavior, and suspension stability of palygorskite was discussed. The homogenization process could favor the migration of anions onto palygorskite. It was found that the structure maker anions (H2PO4–, HSO4–, HPO42–, SO42–, and PO43–) made the surface of palygorskite more negatively charged. The flow curve measurements demonstrated that the association capacity of rods depended on the surface potential of palygorskite. A stable suspension was obtained when palygorskite was dispersed in K2SO4 solutions and homogenized at 30 MPa.
Co-reporter:Jintao Wang;Aiqin Wang
Fibers and Polymers 2013 Volume 14( Issue 11) pp:1834-1840
Publication Date(Web):2013 November
DOI:10.1007/s12221-013-1834-4
A novel kapok fiber-based sorbent for oil absorption was successfully prepared by the modification of kapok fiber with acetic anhydride using pyridine as a catalyst. The acetylated kapok fiber was characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The effects of volume ratio of pyridine to acetic anhydride, reaction temperature and time on the oil absorbency were investigated. The highest oil absorbency of as-prepared acetylated kapok fiber was 44.0 g/g, 52.5 g/g, and 84.4 g/g for cyclohexane, toluene, and chloroform, respectively. In addition, the oil absorbency for cyclohexane, toluene, and chloroform reduces by 33.9 %, 39.0 %, and 35.7 % after recycling nine times, respectively. Therefore, the natural renewable kapok fiber could replace those of non-biodegradable oil sorbents in removing toxic organic solvents from industrial sewage.
Co-reporter:Wenbo Wang;Yuru Kang;Aiqin Wang
Journal of Polymer Research 2013 Volume 20( Issue 3) pp:
Publication Date(Web):2013 March
DOI:10.1007/s10965-013-0101-0
Granular alginate-based hydrogels were prepared in situ in an aqueous solution via grafting and crosslinking reactions among sodium alginate (SA), acrylic acid (AA), polyvinylpyrrolidone (PVP), and gelatin (GE). Fourier transform infrared spectra, elemental analysis, and scanning electrical microscopy revealed that AA monomers were grafted onto an SA backbone, and that PVP and GE were present in the hydrogel network as linear interpenetrating components. The grafting polymerization and crosslinking reaction between only SA and AA yielded a bulk gel, but the introduction of PVP and GE into the reaction mixture led to the formation of granular products. Electrostatic and hydrogen-bonding interactions among SA, PAA, PVP, and GE were the main driving forces for the formation of granular products. The adsorption isotherms and adsorption kinetics were evaluated for the adsorption of model heavy-metal ions on one of the hydrogels. The results indicated that the hydrogel has satisfactory adsorption capacities (3.028 mmol/g, Ni2+; 3.146 mmol/g, Cu2+; 2.911 mmol/g, Zn2+; 2.862 mmol/g, Cd2+), adsorption rates, and recovery capacities for the target metal ions. In addition, competitive adsorption results suggested that the hydrogel has a stronger affinity for Cu2+ ion than for the other ions.
Co-reporter:Wen-Bo Wang, Da-Jian Huang, Yu-Ru Kang, Ai-Qin Wang
Colloids and Surfaces B: Biointerfaces 2013 Volume 106() pp:51-59
Publication Date(Web):1 June 2013
DOI:10.1016/j.colsurfb.2013.01.030
The novel granular semi-IPN hydrogels were in situ prepared in an aqueous solution by the free-radical grafting and crosslinking reactions among chitosan (CTS), acrylic acid (AA), gelatin (GE) and N,N′-methylene-bis-acrylamide. The FTIR spectra and elemental analysis confirmed that the AA monomers were grafted onto CTS backbone, and the GE macromolecular chains interpenetrated through the CTS-g-PAA network. The hydrogels are granular, which are composed of numerous micro-spheres according to the scanning electron microscope observations. The gel strength, adsorption, reuse and recovery properties of the hydrogels for Cu2+ ion were systematically investigated. The results indicate the hydrogel with 2 wt% GE has the highest adsorption capacity of 261.08 mg/g with the recovery ratio of 95.2%. And the incorporation of 10 wt% GE enhanced the storage modulus by 103.4% (ω = 100 rad/s) and 115.1% (ω = 0.1 rad/s), and the adsorption rate by 5.67%. Moreover, the adsorption capacity of the hydrogel is still as high as 153.9 mg/g, after five cycles of adsorption–desorption. It was found that the ion-exchange and complexation interactions between the functional groups (COO− and NH2) of the hydrogels and Cu2+ ion are the predominant adsorption mechanisms.Graphical abstractA granular semi-IPN hydrogel with excellent Cu2+ adsorption performance was in situ synthesized from aqueous system by one-step grafting polymerization among chitosan, acrylic acid and gelatin.Highlights► Granular semi-IPN hydrogel was prepared by one-step in situ solution polymerization. ► Gel strength was improved by introducing gelatin to form a semi-IPN network. ► The semi-IPN hydrogel shows better adsorption and recovery capability to Cu2+ ions. ► Formation mechanism of granule and its adsorption mechanism on Cu2+ were explored.
Co-reporter:Yizhe Wang;Wenbo Wang;Xiaoning Shi;Aiqin Wang
Polymer Bulletin 2013 Volume 70( Issue 4) pp:1181-1193
Publication Date(Web):2013 April
DOI:10.1007/s00289-012-0901-0
In this work, a series of sodium alginate-g-poly(sodium acrylate-co-sodium p-styrenesulfonate)/attapulgite (NaAlg-g-poly(NaA-co-NaSS)/APT) superabsorbent composites were prepared by graft copolymerization using N,N’-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate as an initiator. Fourier transform infrared spectroscopy revealed that NaA and NaSS had been grafted onto NaAlg, and APT participated in polymerization reaction through reactive –OH groups. The introduction of proper amount of NaSS and APT induced the improved surface morphology, swelling capacity, and swelling rate. Moreover, the swelling behaviors of the superabsorbent composites were remarkably influenced by various salt medium, pH buffer solutions and organic solvents, and especially an intriguing swelling–deswelling behavior was observed with altering water/organic solvent ratio.
Co-reporter:Yian Zheng and Aiqin Wang
Journal of Materials Chemistry A 2012 vol. 22(Issue 32) pp:16552-16559
Publication Date(Web):25 Jun 2012
DOI:10.1039/C2JM32774K
A granular hydrogel based on chitosan (CTS) and acrylic acid (AA) was prepared using Fenton’s reagent as the redox initiator and N,N′-methylenebisacrylamide as the crosslinker under ambient conditions. The resulting three-dimensional (3D) networks can serve as micro- or nano-reactors for the production of highly stable silver nanoparticles by the in situ reduction of silver nitrate (AgNO3) with sodium borohydride (NaBH4) as reducing agent and Al3+ as surface crosslinking agent. The as-prepared Ag-entrapped hydrogel was successfully confirmed by means of Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA), and then tested to catalyze the NaBH4 reduction of two organic dyes: methylene blue (MB) and Congo red (CR). The catalytic results indicate that within 30 min, MB and CR with an initial concentration of 20 mg L−1 can be reduced completely, and the catalytic activity is independent of initial pH and ion strength. In addition, the Ag-entrapped hydrogel shows excellent reusability for ten successive cycles, with no appreciable decrease in the catalytic effects.
Co-reporter:Yi Liu;Yuru Kang;Dajian Huang;Aiqin Wang
Journal of Chemical Technology and Biotechnology 2012 Volume 87( Issue 7) pp:1010-1016
Publication Date(Web):
DOI:10.1002/jctb.3722
Abstract
BACKGROUND: The adsorption of Cu2+ from aqueous solution using crosslinked chitosan hydrogels impregnated with Congo Red (CR) by ion-imprint technology was systematically investigated with particular reference to the effects of contact time, pH, and initial concentration on adsorption.
RESULTS: The adsorption capacity of the crosslinked chitosan without impregnation was only 68.68 mg g−1 for Cu2+. However, the adsorption capacity increased from 77.42 (without imprint ion) to 84.54 mg g−1 (imprint ion content 0.5 mmol) after the chitosan was impregnated with a ratio of 1/12 of CR to chitosan. The as-prepared adsorbents were found to be pH-dependent and the process of adsorption agreed well with the Freundlich isotherm. The loaded adsorbents could be regenerated and reused without the appreciable loss of capacity.
CONCLUSION: Chitosan hydrogels impregnated with CR showed higher Cu2+ adsorption capacities compared with those prepared conventionally without imprint ion, and thus developed a good approach to increase Cu2+ adsorption efficiency in the treatment of waste-water. Copyright © 2012 Society of Chemical Industry
Co-reporter:Yian Zheng, Yi Liu, and Aiqin Wang
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 30) pp:10079-10087
Publication Date(Web):July 6, 2012
DOI:10.1021/ie300246m
In the present work, kapok fiber oriented polyaniline (KF-O-PAN) was prepared via a facile polymerization of aniline on the surface of KF and optimized using response surface methodology based on a central composite design. Adsorption characteristics of KF-O-PAN were examined using three sulfonated dyes, that is, Congo Red (CR), Orange II (OG-II), and Orange G (OG-G), as the model adsorbates. The effects of contact time, pH, initial dye concentration, and poly(vinyl alcohol) sizing on the amount of dye adsorbed were investigated using a batch experiment. The amount of dye adsorbed in different water bodies including distilled water, tap water, well water, and lake water was compared to study further the influence of ionic strength. The results indicate that the adsorption equilibrium can be achieved within 4 h, and the monolayer adsorption capacity calculated from the Langmuir equation is 40.82, 188.7, and 192.3 mg/g for CR, OG-II, and OG-G, respectively. KF-O-PAN shows a higher amount of dye adsorbed despite the influences of ionic strength when pH ≤ 8 except for CR. The higher desorption efficiency using NaOH solution and multiple adsorption–desorption cycles suggests the potential of KF-O-PAN for efficient removal of sulfonated dyes from aqueous solution.
Co-reporter:Yi Liu, Wenbo Wang, Aiqin Wang
Powder Technology 2012 Volume 225() pp:124-129
Publication Date(Web):July 2012
DOI:10.1016/j.powtec.2012.03.049
Palygorskite (PAL) was treated by a facile grinding technology. The effects of dry grinding treatment on the morphology, crystal structure, specific surface area, pore structure of PAL were explored by Fourier transform infrared (FTIR) spectra, field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and UV/visible techniques. FESEM and XRD results showed that the dry grinding treatment could dissociate the crystal bundles of PAL, but the aspect ratio of rod-like crystals was decreased. As PAL with dry grinding treatment of 2 times, the great enhancement in specific surface area of 153 to 229 m2/g, micropore area of 28 to 103 m2/g, micropore volume of 0.012 to 0.047 cm3/g was observed. It was confirmed that the dry grinding treatment is favorable to generate mesopores and micropores, but almost has no influences on the total pore volume and external surface area. The adsorption efficiencies of grinded PAL for methylene blue (MB) were enhanced owing to the availability of more shielded adsorption sites and increasing specific surface area, micropore volume and mesopore volume.The dry grinding treatment can disaggregate the crystal bundles of palygorskite and is favorable to generate mesopores and micropores. The adsorption efficiencies of grinded palygorskite for methylene blue were enhanced owing to the availability of more shielded adsorption sites and increasing specific surface area, micropore volume and mesopore volume.Highlights► The grinding treatment on PAL could dissociate the crystal bundles. ► BET and pore volume of PAL were greatly enlarged after grinding. ► The external surface area of PAL had little change after grinding. ► The adsorption capacity of PAL for MB was enhanced after grinding.
Co-reporter:Dajian Huang, Bin Mu, Aiqin Wang
Materials Letters 2012 Volume 86() pp:69-72
Publication Date(Web):1 November 2012
DOI:10.1016/j.matlet.2012.07.020
Biodegradable polymer/clay nanocomposites have aroused intense research interests due to their many attractive properties. Sepiolite (SP) has been used as reinforce filler of nanocomposites for its available abundance, thermal stability, higher mechanical strength, and low cost. To evaluate the effect of SP as a nanofiller on the properties of nanocomposites, we prepared a series of nanocomposites by a solution casting method with SP introduced into chitosan (CS)/poly (vinyl alcohol) (PVA) matrix. The results indicated that the mechanical properties of nanocomposites were improved sharply with an increase in SP loading. The moisture uptake (MU) of nanocomposites was decreased with introducing SP into the polymer matrix.Highlights► SP could be well dispersed in a CS/PVA matrix by a solution casting method. ► SP could improve the mechanical properties of nanocomposite films. ► MU of nanocomposites films decreases with the increase in SP content from 0% to 4%.
Co-reporter:Dajian Huang;Wenbo Wang;Yuru Kang;Aiqin Wang
Polymer Composites 2012 Volume 33( Issue 10) pp:1693-1699
Publication Date(Web):
DOI:10.1002/pc.22302
Abstract
Biodegradable polymer/clay nanocomposites have attracted tremendous attentions because of their excellent properties and ecofriendly advantages. In this article, a series of nanocomposite films were prepared by introducing of halloysite nanotubes (HTs) into chitosan (CS)/poly(vinyl alcohol) (PVA) matrix using the solution casting method, and the effect of HT as nanofillers on the properties of polymer/HT nanocomposites was explored. The results indicated that the tensile strength of CS/PVA/HT3 and elongation at break of CS/PVA/HT2 sharply increased by 39.72% and 26.14% in comparison with the pure CS/PVA film, respectively. The water resistance and thermal stability of polymer/HT nanocomposites were also improved compared with the pure CS/PVA film, but the optical property of the nanocomposite films was not affected by introducing HT into the CS/PVA matrix. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Co-reporter:Qin Wang;Wenbo Wang;Jie Wu;Aiqin Wang
Journal of Applied Polymer Science 2012 Volume 124( Issue 6) pp:4424-4432
Publication Date(Web):
DOI:10.1002/app.35440
Abstract
A series of pH-sensitive composite hydrogel beads, carboxymethyl cellulose-g-poly(acrylic acid)/attapulgite/sodium alginate (CMC-g-PAA/APT/SA), were prepared by combining CMC-g-PAA/APT composite and SA, using Ca2+ as the ionic crosslinking agent and diclofenac sodium (DS) as the model drug. The effects of APT content and external pH on the swelling properties and release behaviors of DS from the composite hydrogel beads were investigated. The results showed that the composite hydrogel beads exhibited good pH-sensitivity. Introducing 20% APT into CMC-g-PAA hydrogel could change the surface structure of the composite hydrogel beads, decrease the swelling ability, and relieve the burst release effect of DS. The drug cumulative release ratio of DS from the hydrogel beads in simulated gastric fluid was only 3.71% within 3 hour, but in simulated intestinal fluid about 50% for 3 hour, 85% for 12 hour, up to 90% after 24 hour. The obtained results indicated that the CMC-g-PAA/APT/SA hydrogel beads could be applied to the drug delivery system as drug carriers in the intestinal tract. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Co-reporter:Xiaoning Shi;Wenbo Wang;Yuru Kang;Aiqin Wang
Journal of Applied Polymer Science 2012 Volume 125( Issue 3) pp:1822-1832
Publication Date(Web):
DOI:10.1002/app.36230
Abstract
A novel alginate-based superabsorbent composite with enhanced swelling properties was synthesized by simultaneously grafted copolymerization partially neutralized acrylic acid (NaA), styrene (St) onto the sodium alginate (NaAlg) backbones in the presence of attapulgite (APT). The structure and morphology of the synthesized superabsorbent composites were characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-vis) spectra and Field emission scanning electron microscope (FESEM). Major factors affecting the swelling ratio according to Flory's theory were discussed. The superabsorbent composite synthesized under optimum reaction conditions exhibits the maximum swelling ratio of 587 g/g in distilled water and 73 g/g in 0.9 wt % NaCl solution. Compared with NaAlg-g-PNaA hydrogel, the simultaneous introduction of tiny amount of St and APT not only enhanced the swelling ratio but also increased the initial swelling rate. In addition, the effects of salt and pH medium on the swelling behaviors were investigated, and the results indicated that the composite showed smart swelling behavior in multivalent salt solution and better pH-responsitivity in the pH 2.2 and 7.4 solutions, which makes it promising for drug delivery application. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Jixiang Xu, Wenbo Wang, Bin Mu, Aiqin Wang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2012 Volume 405() pp:59-64
Publication Date(Web):5 July 2012
DOI:10.1016/j.colsurfa.2012.04.037
Palygorskite was modified with inorganic sulfates, including Na2SO4, ZnSO4, Al2(SO4)3, and Zr(SO4)2, using the high-pressure homogenization technology. The effects of type and concentration of sulfates on the morphology, micro-structure, surface potential, shear modulus and viscosity of palygorskite were investigated by scanning electron microscopy (SEM), nitrogen adsorption–desorption isotherms (BET), zeta potential and rheological measurements, respectively. The modification of palygorskite with ZnSO4 increased its specific surface area and micropore volume, but the largest pore size was obtained for the palygorskite modified with Al2(SO4)3. Zeta potential results suggested that the multivalent Al3+ and Zr4+ ions were more efficient in reducing the negative charge of palygorskite. The colloidal properties of the suspension were dependent on the type and concentration of sulfates, and the introduction of ZnSO4 simultaneously enhanced the dispersibility and colloidal properties of palygorskite.Graphical abstractThe addition of various sulfates (Na2SO4, ZnSO4, Al2(SO4)3 and Zr(SO4)2) into palygorskite have different influences on the microstructural parameters, zeta potential and rheological properties of treated samples.Highlights► The structure and properties of sulfates modified palygorskite clay were investigated. ► Effects of sulfate type and loading on rheological, zeta-potential of clay were studied. ► The zeta-potential of treated samples followed the sequences: Al3+ < Zr4+ < Na+ < Zn2+. ► The shear modulus and viscosity of suspension improved after addition of 2.0% ZnSO4.
Co-reporter:Jixiang Xu and Aiqin Wang
Journal of Chemical & Engineering Data 2012 Volume 57(Issue 5) pp:1586-1593
Publication Date(Web):April 5, 2012
DOI:10.1021/je300213u
A series of palygorskite samples modified with electrolytes containing LiCl, NaCl, KCl, CsCl, MgCl2, CaCl2, AlCl3, and FeCl3 were prepared with the aid of high-pressure homogenization and mechanical stirring techniques. The changes of electrokinetic and colloidal properties of modified palygorskite were investigated in detail through the measurement of the zeta potential, yield stress, and sedimentation volume. The influences of charge, concentration, and type of ions on the surface potential of palygorskite were compared. The correlation between the zeta potential and the colloidal properties of obtained palygorskite was discussed. The homogenization process could favor the adsorption of ions onto palygorskite surface and enhance the colloidal properties of suspension. It was found that the 0.05 mol·kg–1 AlCl3 and FeCl3 reversed the surface charge of palygorskite from negative to positive. The yield stress measurements demonstrated that the association capacity of rods depended on the surface potential and interparticle interactions of palygorskite. A stable suspension was obtained when palygorskite was dispersed in MgCl2 solutions and homogenized at 30 MPa.
Co-reporter:Yian Zheng, Dajian Huang, Aiqin Wang
Analytica Chimica Acta 2011 Volume 687(Issue 2) pp:193-200
Publication Date(Web):21 February 2011
DOI:10.1016/j.aca.2010.12.026
In this study, chitosan-g-poly(acrylic acid) (CTS-g-PAA) hydrogel with crosslinked polymeric networks was prepared from an aqueous dispersion polymerization and then used as the adsorbent to recover a valuable metal, Ni2+. The adsorption capacity of CTS-g-PAA for Ni2+ was evaluated and the adsorption kinetics was investigated using Voigt-based model and pseudo-second-order model. In addition, the effects of pH values and coexisting heavy metal ions such as Cu2+ and Pb2+ on the adsorption capacity were studied. The results indicate that the as-prepared adsorbent has faster adsorption rate and higher adsorption capacity for Ni2+ recovery, with the maximum adsorption capacity of 161.80 mg g−1. In a wide pH range of 3–7, the adsorption capacity keeps almost the same, and even under competitive conditions, the adsorption capacity of CTS-g-PAA for Ni2+ is observed to be as high as 54.47 mg g−1. Finally, the adsorption performance of CTS-g-PAA for Ni2+ in real water sample and the reusability of the as-prepared adsorbent were evaluated, and also the controlled adsorption mechanism was proposed.
Co-reporter:Wenbo Wang;Aiqin Wang
Polymers for Advanced Technologies 2011 Volume 22( Issue 12) pp:1602-1611
Publication Date(Web):
DOI:10.1002/pat.1647
Abstract
Utilization of naturally available raw materials for the fabrication of eco-friendly functional materials has long been desired. In this work, a series of superabsorbent nanocomposites were prepared by radical solution copolymerization of sodium carboxymethyl cellulose (CMC), partially neutralized acrylic acid (NaA), and rectorite (REC) in the presence of initiator ammonium persulfate (APS) and crosslinker N,N'-methylene-bis-acrylamide (MBA). The optimal reaction variables including the mass ratio of acrylic acid (AA) to CMC, MBA concentration, and REC content were explored. FTIR spectra confirmed that NaA had been grafted onto CMC and REC participated in polymerization. REC was exfoliated and uniformly dispersed in the CMC-g-PNaA matrix without agglomeration as shown by XRD, TEM, and SEM analysis. The thermal stability, swelling capabilities, and rate of the nanocomposites were improved after introducing REC, and the gel strength greatly depended on the concentration of crosslinker MBA. The nanocomposite showed excellent responsive properties and reversible On–Off switching characteristics in various saline, pH, and hydrophilic organic solvent/water solutions, which provided great possibility to extend the application domain of the superabsorbent nanocomposites such as drug delivery system. Copyright © 2010 John Wiley & Sons, Ltd.
Co-reporter:Wenbo Wang;Naihua Zhai;Aiqin Wang
Journal of Applied Polymer Science 2011 Volume 119( Issue 6) pp:3675-3686
Publication Date(Web):
DOI:10.1002/app.33083
Abstract
A series of novel superabsorbent nanocomposites were prepared by the solution radical polymerization of natural guar gum (GG), partially neutralized acrylic acid [sodium acrylate (NaA)], and cation-exchanged vermiculite (Mn+-VMT) with ammonium persulfate as the initiator in the presence of the crosslinking agent N,N′-methylene-bis-acrylamide. Fourier transform infrared analysis revealed that NaA was grafted onto the GG chains and that Mn+-VMT participated in the polymerization. X-ray diffraction results showed that the occurrence of the cation-exchange process changed the interlayer gap of vermiculite (VMT) and that Mn+-VMT was exfoliated during polymerization to form a nanocomposite. The exfoliated VMT led to better dispersion in the GG-g-poly(sodium acrylate) matrix, as shown by scanning electron microscopy and transmission electron microscopy analysis. Mn+-VMT improved the water absorption of the nanocomposite more remarkably than raw VMT, and Al3+-VMT enhanced the water absorption to the highest degree. The nanocomposite exhibited intriguing overshooting swelling characteristics in a multivalent saline solution and acidic pH solution and showed switching pH-responsive behaviors in buffer solutions between pH 2 and pH 7.2. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Co-reporter:Naihua Zhai;Wenbo Wang;Aiqin Wang
Polymer Composites 2011 Volume 32( Issue 2) pp:210-218
Publication Date(Web):
DOI:10.1002/pc.21017
Abstract
A series of pH-responsive superabsorbent composites were synthesized by the free-radical grafting copolymerization of natural guar gum (GG), partially neutralized acrylic acid (NaA), and medicinal stone (MS) using ammonium persulfate (APS) as the initiator and N,N′-methylene-bis-acrylamide (MBA) as the crosslinker. The structure, surface morphologies, and thermal stability of the developed composites were characterized by FTIR spectra, SEM, and TGA techniques, respectively. The effects of various saline, surfactant, and dye solutions on swelling properties were investigated, and the pH-responsivity was also evaluated. Results indicated that NaA had been grafted onto GG macromolecular chains and MS participated in the polymerization reaction. The incorporation of MS obviously improved the surface structure, thermal stability, water absorption capacity, and rate. Multivalent saline, cationic surfactant, and dye showed more remarkable effect on the water absorption than did monovalent or anionic ones. The composites showed excellent responsive properties and reversible On–Off switching characteristics in various pH buffer solutions, which provided great possibility to extend the application domain of the superabsorbent composites. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers
Co-reporter:Xiao-Ning Shi, Wen-Bo Wang, Ai-Qin Wang
Colloids and Surfaces B: Biointerfaces 2011 Volume 88(Issue 1) pp:279-286
Publication Date(Web):1 November 2011
DOI:10.1016/j.colsurfb.2011.07.002
Novel fast-swelling porous guar gum-g-poly(sodium acrylate-co-styrene)/attapulgite (GG-g-P(NaA-co-St)/APT) superabsorbent hydrogels were prepared by simultaneous free-radical graft copolymerization reaction of guar gum (GG), partially neutralized AA (NaA), styrene (St) and attapulgite (APT) using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator in aqueous solution and the surfactant self-assembling templating pore-forming technique. Fourier transform infrared (FTIR) spectroscopy confirmed that the surfactant could be removed from the final hydrogel product by methanol/water (8:1, v/v) washing process and the surfactant only act as micelle template to form pores. The effect of surfactant type on the porous microstructure of the hydrogel was assessed by field emission scanning electron microscope (FESEM). It was shown that incorporation of proper amount of anionic surfactant sodium n-dodecyl sulfate (SDS) in the gelling process of the hydrogel can obviously enhance the swelling capacity and initial swelling rate. The salt-sensitivity of the SDS-added hydrogel in distilled water and 15 mmol/L NaCl, CaCl2 solution or 15 mmol/L NaCl and CaCl2 solution was investigated, and it was found that the swelling–deswelling capability is quite reversible. A similar reproducible on–off switching behavior was observed in the 1 mmol/L solution of phosphate buffer at pH 2.1 and 7.4.
Co-reporter:Yi Liu;Yian Zheng;Aiqin Wang
Ionics 2011 Volume 17( Issue 6) pp:535-543
Publication Date(Web):2011 July
DOI:10.1007/s11581-011-0552-4
A series of chitosan-g-poly(acrylic acid)/biotite (CTS-g-PAA/BT) hydrogels with unique clay biotite (BT) were prepared and used to remove cationic dye methylene blue (MB) from aqueous solution by batch adsorption experiments. Variables of the system including BT content, initial pH, contact time, initial concentration, and temperature affecting the adsorption efficiency of MB by CTS-g-PAA/BT hydrogels were investigated. Kinetic studies indicated that the adsorption data well followed pseudo-second-order kinetics. Langmuir and Freundlich isotherm models were applied to experimental equilibrium data of MB adsorption depending on temperature. The adsorption equilibrium data obeyed Langmuir isotherm, and the monolayer adsorption capacity calculated from the Langmuir isotherm was 2,125.70 mg/g for CTS-g-PAA/10% BT at 30 °C. The adsorption capacity was much higher compared with other hydrogels with the same content of other clays. The introduction of BT into the hydrogel could effectively improve its adsorption properties and reduce the cost. Thermodynamic parameters were evaluated for the dye-adsorbent systems and revealed that the adsorption process was spontaneous and exothermic in nature. All the information gave an indication that CTS-g-PAA/10% BT could potentially be applied as an efficient adsorbent for cationic dye removal from aqueous solution.
Co-reporter:Wenbo Wang;Qin Wang;Aiqin Wang
Macromolecular Research 2011 Volume 19( Issue 1) pp:57-65
Publication Date(Web):2011 January
DOI:10.1007/s13233-011-0112-9
Novel pH-responsive semi-interpenetrated polymer network (semi-IPN) superabsorbent hydrogels were prepared by the radical graft polymerization of carboxymethylcellulose (CMC) and partially neutralized acrylic acid (NaA) in the presence of a crosslinker, N,N′-methylene-bis-acrylamide (MBA), and linear polyvinylpyrrolidone (PVP). FTIR spectroscopy showed that NaA was grafted onto the CMC backbone and PVP combined with CMC-g-PNaA network by hydrogen-bonding interaction. SEM showed that the formation of a semi-IPN structure improved the surface structure of the hydrogels. The reaction variables, including the mass ratio of acrylic acid (AA) to CMC, MBA concentration and PVP content were optimized, and the crosslinking density of the hydrogels was determined. In addition, the pH-response, swelling behavior of the hydrogel in various saline solutions and aqueous cetyltrimethylammonium bromide (CTAB) solutions were investigated. The results showed that the introduction of CMC and PVP clearly enhanced the swelling capability and rate, and improved the pH-responsive and On-Off switching swelling abilities, salt-resistance, and intriguing time-dependent swelling characteristics.
Co-reporter:Tianpeng Gao;Wenbo Wang;Aiqin Wang
Macromolecular Research 2011 Volume 19( Issue 7) pp:739-748
Publication Date(Web):2011 July
DOI:10.1007/s13233-011-0706-2
Co-reporter:Jinlei Wang;Wenbo Wang;Yian Zheng;Aiqin Wang
Journal of Polymer Research 2011 Volume 18( Issue 3) pp:401-408
Publication Date(Web):2011 May
DOI:10.1007/s10965-010-9430-4
A series of hydroxyethyl cellulose-g-poly(acrylic acid)/vermiculite (HEC-g-PAA/VMT) superabsorbent nanocomposites were prepared by radical solution polymerization among hydroxyethyl cellulose (HEC), partially neutralized acrylic acid (AA), raw vermiculite (RVMT), acidified vermiculite (AVMT) and organo-vermiculite (OVMT) in the presence of initiator ammonium persulfate (APS) and crosslinker N,N’-methylenebisacrylamide (MBA). FTIR results revealed that AA was grafted onto HEC backbone and VMT participated in polymerization. VMT was exfoliated during polymerization reaction and a nanocomposite structure was formed as shown by XRD and TEM analysis. Effects of VMT content, concentration of HCl solution and organification degree of OVMT on water absorbency were investigated and the swelling kinetics of the developed nanocomposites was also evaluated. Results showed that incorporation of VMT greatly enhanced the water absorbency, and the modified VMT by acidification and organification can improve the water absorbency more remarkably than raw one. OVMT can improve the swelling capabilities and swelling rate to the highest degree in contrast to RVMT and AVMT.
Co-reporter:Yian Zheng and Aiqin Wang
Industrial & Engineering Chemistry Research 2010 Volume 49(Issue 13) pp:6034-6041
Publication Date(Web):June 15, 2010
DOI:10.1021/ie9016336
We present here a simple and effective strategy to obtain a series of hydrogel composites using biotite (BT) particles and poly(acrylic acid) (PAA) as the inorganic and organic components, respectively. These hydrogel composites were prepared at room temperature via a self-induced redox system based on ammonium persulfate and Fe(II) arisen from iron-rich BT. After NaOH activation, as-prepared hydrogel composites were used as the adsorbents to remove ammonium (NH4+) from its aqueous solution. The effects of preparation and adsorption conditions on NH4+ removal were investigated. The results show that the adsorption of NH4+ onto as-prepared PAA/BT (30%) is complete within 15 min, with the equilibrium adsorption capacity of 32.87 mg N/g at an initial NH4+ concentration of 100 mg N/L. In addition, the reusability of as-prepared PAA/BT for NH4+ removal was evaluated and the adsorption mechanism of NH4+ onto as-prepared hydrogel composite was proposed.
Co-reporter:Li Wang;Qi Li;Aiqin Wang
Polymer Bulletin 2010 Volume 65( Issue 9) pp:961-975
Publication Date(Web):2010 December
DOI:10.1007/s00289-010-0363-1
In order to improve the adsorption capacity of chitosan (CTS) for methylene blue (MB) cationic dye, a series of N,O-carboxymethyl-chitosans (N,O-CMCTS) were prepared under heterogeneous conditions by controlling the reaction time. The adsorption of MB from aqueous solution onto N,O-CMCTS was studied. The effects of degree of substitution (DS) of N,O-CMCTS, initial pH of the dye solution and adsorption temperature were investigated in detail. The results showed that the adsorption capacities of N,O-CMCTS increased with the increase of DS and N,O-CMCTS with DS of 0.72 exhibited the highest adsorption capacity (349 mg/g). The adsorption kinetics of N,O-CMCTS was found to follow the pseudo-second-order model. The adsorption equilibrium of N,O-CMCTS fitted very well with the Langmuir isotherm model, showing maximum monolayer adsorption capacity of 351 mg/g. The adsorption mechanism of N,O-CMCTS was also discussed by means of FTIR spectra and XPS. The results revealed that the –OH, –NH2, and –COOH groups of N,O-CMCTS were involved in the adsorption process. The desorption studies showed that N,O-CMCTS could be regenerated and used for the adsorption of MB repeatedly.
Co-reporter:Wenbo Wang, Aiqin Wang
Carbohydrate Polymers 2010 80(4) pp: 1028-1036
Publication Date(Web):
DOI:10.1016/j.carbpol.2010.01.020
Co-reporter:Junping Zhang and Aiqin Wang
Journal of Chemical & Engineering Data 2010 Volume 55(Issue 7) pp:2379-2384
Publication Date(Web):February 16, 2010
DOI:10.1021/je900813z
A series of chitosan-g-poly(acrylic acid)/attapulgite/sodium humate (CTS-g-PAA/APT/SH) composite hydrogels incorporated with various amounts of APT were used as adsorbents for the removal of Pb(II) from aqueous solution. The effects of adsorption (pH and concentration of Pb(II) in solution, dosage and particle size of composite hydrogels) and desorption (the kind and concentration of desorbing agent, recyclability) parameters are discussed in detail from use of a batch adsorption technique. The results showed that the adsorption capacity of the CTS-g-PAA/APT/SH composite hydrogels for Pb(II) increases with increasing pH and concentration of Pb(II) in solution but decreases with increasing adsorbent dosage. It is found that the composite hydrogel with a particle size of (40 to 100) mesh is an appropriate choice. The adsorption isotherms of the CTS-g-PAA/APT/SH composite hydrogels for Pb(II) could be described very well by the Langmuir equation, but not the Freundlich equation. Considering the economy and performance, 0.05 M HCl solution is the best desorbing agent. The introduced APT and SH are a benefit for recycling the composite hydrogel, and the adsorption capacity is still higher than 590 mg·g−1 after five consecutive adsorption−desorption processes.
Co-reporter:Yian Zheng and Aiqin Wang
Journal of Chemical & Engineering Data 2010 Volume 55(Issue 9) pp:3494-3500
Publication Date(Web):August 25, 2010
DOI:10.1021/je100169r
In this study, poly(dimethyl diallyl ammonium chloride)/polyacrylamide (PDMDAAC/PAM), a hydrogel containing quaternary ammonium groups, was prepared and used as the adsorbent to remove the nitrate anion from aqueous solution. The effects of operating conditions, such as PDMDAAC content, contact time, pH, initial nitrate concentration, temperature, ion strength, and the presence of the competitive ion phosphate on the adsorption capacities were examined. The Langmuir, Freundlich, and Redlich−Peterson isotherms were used to describe the adsorption experimental data. The results indicate that the adsorption equilibrium can be achieved within 60 min, and the hydrogel has an increasing adsorption capacity with increasing PDMDAAC content up to 50 % (by weight). As-prepared hydrogel shows an appreciable adsorption capacity within the pH range of 5 to 9, and the calculated maximum adsorption capacity is found to be (1.1 to 1.4) mmol·g−1. The hydrogel with higher PDMDAAC content is sensitive to the changes in the ion strength and competitive anion concentration. Effective desorption of nitrate is achieved using strong acid or base as the desorbing agent. It is proposed that two mechanisms are responsible for the higher adsorption capacity: one is swelling, and the other is electrostatic attraction.
Co-reporter:Yongfeng Zhu, Yian Zheng, Wenbo Wang, Aiqin Wang
Journal of Water Process Engineering (September 2015) Volume 7() pp:218-226
Publication Date(Web):1 September 2015
DOI:10.1016/j.jwpe.2015.06.010
A series of granular hydrogels containing carboxy group and thiourea group were prepared by a facile redox-initiated polymerization in air atmosphere at room temperature, and then were used as the adsorbents for efficient adsorption of Pb(II) and Hg(II). The variables affecting the adsorption capacity were systematically investigated, including pH, initial concentration, contact time, and desorption and reusability. The results indicate that the as-prepared adsorbent has fast adsorption kinetics and high adsorption capacity, in particular for Hg(II), with the equilibrium time of about 40 min and the maximum adsorption capacity of 1106.72 mg/g for Hg(II). Over the pH range studied, this granular hydrogel shows insignificant changes in the adsorption capacity for Hg(II), while some noticeable differences are visible for Pb(II). The adsorption process for Pb(II) and Hg(II) can be described using the pseudo-second-order kinetic model and the equilibrium isotherm matches well with the Langmuir model. The reusability demonstrates that after five adsorption–desorption cycle, a high adsorption capacity is still observed for Pb(II) and Hg(II), though a decreasing tendency is inevitable. Consequently, the as-prepared granular hydrogel can be recognized as an effective adsorbent for the removal and recovery of heavy metal ions, especially for Hg(II) from aqueous solution.Download high-res image (160KB)Download full-size image
Co-reporter:Shuibo Hua, Huixia Yang, Wenbo Wang, Aiqin Wang
Applied Clay Science (September 2010) Volume 50(Issue 1) pp:112-117
Publication Date(Web):September 2010
DOI:10.1016/j.clay.2010.07.012
Co-reporter:Wenbo Wang, Guangyan Tian, Zhifang Zhang, Aiqin Wang
Applied Clay Science (November 2016) Volumes 132–133() pp:438-448
Publication Date(Web):November 2016
DOI:10.1016/j.clay.2016.07.013
Co-reporter:Bin Mu, Jie Tang, Long Zhang, Aiqin Wang
Applied Clay Science (November 2016) Volumes 132–133() pp:7-16
Publication Date(Web):November 2016
DOI:10.1016/j.clay.2016.06.005
Co-reporter:Jixiang Xu, Junping Zhang, Qin Wang, Aiqin Wang
Applied Clay Science (November 2011) Volume 54(Issue 1) pp:118-123
Publication Date(Web):November 2011
DOI:10.1016/j.clay.2011.07.020
Co-reporter:Yongfeng Zhu, Yian Zheng, Aiqin Wang
Journal of Environmental Chemical Engineering (June 2015) Volume 3(Issue 2) pp:1416-1425
Publication Date(Web):1 June 2015
DOI:10.1016/j.jece.2014.11.028
•Granular hydrogel composite was prepared at room temperature by a facile approach.•Introducing APT into hydrogel is beneficial for the adsorption of rare elements.•This adsorbent shows fast adsorption rate and high adsorption capacity.•This adsorbent can be easily regenerated for succeeding adsorption cycles.A series of granular grafted hydrogel composites were prepared at room temperature and atmospheric conditions by aqueous radical polymerization initiated by the redox couple Vc/H2O2 using chitosan (CTS) as the backbone, acrylic acid (AA) as the monomer, and attapulgite (APT) as the inorganic component, and the resulting products, labeled as CTS-g-PAA/APT, were then applied as the adsorbent to adsorption La(III) and Ce(III) from aqueous solution. The variables affecting the adsorption capacity for La(III) and Ce(III) were investigated, including the contact time, initial concentration, pH, and APT content, etc. The results show that the as-prepared adsorbent has fast adsorption rate and high adsorption capacity for La(III) and Ce(III) in a wide pH range. The adsorption equilibrium for La(III) and Ce(III) can be reached within 40 min and the maximum adsorption capacity for La(III) and Ce(III) is 333.33 and 243.90 mg/g, respectively. An appropriate addition of APT is beneficial for the adsorption process, Finally, the regeneration ability was evaluated for the hydrogel composite, with the observation that after five consecutive adsorption–desorption cycles, the composite still has a good adsorption capacity for La(III) and Ce(III). These information imply that the hydrogel composite can be used as an effective adsorbent for the removal and recovery of La(III) and Ce(III) from aqueous solution.Download high-res image (371KB)Download full-size image
Co-reporter:Jixiang Xu, Wenbo Wang, Aiqin Wang
Applied Clay Science (June 2014) Volume 95() pp:365-370
Publication Date(Web):June 2014
DOI:10.1016/j.clay.2014.02.011
Co-reporter:Wenbo Wang, Guangyan Tian, Li Zong, Yanmin Zhou, ... Aiqin Wang
Journal of Environmental Sciences (January 2017) Volume 51() pp:31-43
Publication Date(Web):1 January 2017
DOI:10.1016/j.jes.2016.09.008
A series of mesoporous silicate adsorbents with superior adsorption performance for hazardous chlortetracycline (CTC) were sucessfully prepared via a facile one-pot hydrothermal reaction using low-cost illite/smectite (IS) clay, sodium silicate and magnesium sulfate as the starting materials. In this process, IS clay was “teared up” and then “rebuilt” as new porous silicate adsorbent with high specific surface area of 363.52 m2/g (about 8.7 folds higher than that of IS clay) and very negative Zeta potential (− 34.5 mV). The inert SiOSi (Mg, Al) bonds in crystal framework of IS were broken to form Si(Al) O− groups with good adsorption activity, which greatly increased the adsorption sites served for holding much CTC molecules. Systematic evaluation on adsorption properties reveals the optimal silicate adsorbent can adsorb 408.81 mg/g of CTC (only 159.7 mg/g for raw IS clay) and remove 99.3% (only 46.5% for raw IS clay) of CTC from 100 mg/L initial solution (pH 3.51; adsorption temperature 30°C; adsorbent dosage, 3 g/L). The adsorption behaviors of CTC onto the adsorbent follows the Langmuir isotherm model, Temkin equation and pseudo second-order kinetic model. The mesopore adsorption, electrostatic attraction and chemical association mainly contribute to the enhanced adsorption properties. As a whole, the high-efficient silicate adsorbent could be candidates to remove CTC from the wastewater with high amounts of CTC.Download high-res image (336KB)Download full-size image
Co-reporter:Wenbo Wang, Aiqin Wang
Applied Clay Science (January 2016) Volume 119(Part 1) pp:18-30
Publication Date(Web):January 2016
DOI:10.1016/j.clay.2015.06.030
Co-reporter:Zhifang Zhang, Wenbo Wang, Yuru Kang, Li Zong, Aiqin Wang
Applied Clay Science (February 2016) Volume 120() pp:
Publication Date(Web):February 2016
DOI:10.1016/j.clay.2015.11.019
•Natural PAL was modified with organic acids by a simple hydrothermal process.•The adsorption properties of PAL for dyes were sharply enhanced after modification.•The structural evolution of PAL and functional groups contributes to the adsorption.•The PAL-derived adsorbents can be used as eco-friendly adsorbent for dyes.Naturally abundant palygorskite (PAL) has been frequently used as an efficient, stable, low cost and environment-benign adsorbent to remove toxic pollutants for alleviating their harm to human health. However, the adsorption capacity of natural PAL is limited, which restricts its applications as an efficient adsorbent. As the aim to improve the adsorption capability of natural PAL and develop a high-efficient silicate adsorbent, the organic acids with different structures (i.e., acetic acid, glycolic acid, glycine, chloroacetic acid, benzoic acid, oxalic acid and citric acid) were employed to modify natural PAL via a simple one-step hydrothermal process. The effect of hydrothermal process in the presence of organic acids on the microscopic structure, physico-chemical features and adsorption properties of the PAL-derived adsorbent was studied comparatively using the dyes methylene blue (MB), methyl violet (MV) and malachite green (MG) as the model pollutants. It was found that the structural evolution of PAL and the introduction of functional groups positively contribute to improve the adsorption capacity. The PAL-derived adsorbents in the presence of chloroacetic acid (CAA-PAL) and citric acid (CA-PAL) show excellent adsorption capacity, which could almost completely remove the MB, MV and MG dyes from 200 mg/L of the solution, but the raw PAL can only remove 59% (for MB), 63% (for MV) and 88% (for MG). The intensified electrostatic attraction, hydrogen-bonding interaction and chemical association of –Si–O− groups with dyes, resulting from the hydrothermal evolution of PAL crystal, are primarily responsible for the enhancement of adsorption capacity.
Co-reporter:Jixiang Xu, Wenbo Wang, Aiqin Wang
Applied Clay Science (December 2013) Volume 86() pp:174-178
Publication Date(Web):December 2013
DOI:10.1016/j.clay.2013.10.006
Co-reporter:Zhifang Zhang, Wenbo Wang, Aiqin Wang
Applied Clay Science (April 2015) Volume 107() pp:230-237
Publication Date(Web):April 2015
DOI:10.1016/j.clay.2015.02.004
Co-reporter:Zhifang Zhang, Wenbo Wang, Aiqin Wang
Journal of Environmental Sciences (1 July 2015) Volume 33() pp:106-115
Publication Date(Web):1 July 2015
DOI:10.1016/j.jes.2014.12.014
Attapulgite (APT) has been frequently used for the adsorptive removal of dyes from aqueous solution owing to its unique one-dimensional nanoscale structure and low-cost, abundant, eco-friendly advantages. In this work, APT was functionalized under mild hydrothermal condition using chloroacetic acid (CA) with COOH functional groups to improve its adsorption properties. The effect of hydrothermal modification on the microstructure and physicochemical features of APT was investigated by Fourier transform infrared spectroscopy, X-ray diffraction and Field-emission scanning electron microscopy analyses. The effects of hydrothermal reaction parameters on the adsorption properties of modified APT were intensively investigated. It was revealed that the rearrangement of crystal structure and the surface functionalization of APT with COOH groups cause the surprising increase of adsorption capability for Methylene Blue (MB). The removal ratio of raw APT for MB is only 59.52%, while modified APT could almost completely remove MB in the 200 mg/L of MB solution with a removal ratio of 99.8%. The adsorption kinetics fitted pseudo second-order kinetic model, and the adsorption isotherm could be described with Langmuir isotherm model very well. The hydrogen-bonding interaction, electrostatic attraction and chemical association are the main driving force for the adsorption process.Download full-size image
Co-reporter:Guangyan Tian, Wenbo Wang, Bin Mu, Qin Wang, Aiqin Wang
Ceramics International (1 February 2017) Volume 43(Issue 2) pp:
Publication Date(Web):1 February 2017
DOI:10.1016/j.ceramint.2016.10.145
A series of clay/Fe2O3 red hybrid pigments with vivid color, good stability and low cost was synthesized via a facile one-step reaction of Fe(III) solution with sepiolite (Sep) or halloysite (HNTs). Sep or HNTs plays key roles to promote the in-situ transformation of Fe(III) into red hybrid pigments, because only black product was formed from Fe(III) in the absence of them. The addition of Sep and HNTs avoids the usage of any chemical precipitants, which is greatly superior to the traditional process. The a* coordinate values of the sepiolite/Fe2O3 (Sep/Fe2O3) and halloysite/Fe2O3 (HNTs/Fe2O3) hybrid pigments are 25.1 and 34.4, respectively, which indicate they have well red color performance. The positive influence of Sep or HNTs on the crystallization process and dispersion of Fe2O3 particles is responsible for the good red color. In addition, the hybrid pigments exhibit excellent stability to resist external attacks such as light, acid, alkaline, organic solvents and high temperature, and can be facilely spray-coated onto various substrates, e.g., glass, wood plate, ceramic plate, stone plate, and polyester plate, etc. Therefore, they are potential to be used as promising low-cost environment-friendly colorants in many fields such as ceramic, painting, coating, and printing.
Co-reporter:Bin Mu and Aiqin Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 1) pp:NaN289-289
Publication Date(Web):2014/11/04
DOI:10.1039/C4TA05367B
Multifunctional superparamagnetic attapulgite/Fe3O4/polyaniline (APT/Fe3O4/PANI) nanocomposites have been fabricated by a one-pot process using Fe(III) as the oxidant for aniline and the precursor of Fe3O4 in the presence of attapulgite. The introduction of attapulgite can effectively induce the uniform encapsulation of polyaniline and Fe3O4 nanoparticles on the surface of attapulgite to form the Anthurium andraeanum-like structure, preventing the formation of free aggregates of polyaniline and Fe3O4 nanoparticles. The morphologies and the magnetic properties of the as-prepared nanocomposites can be facilely controlled by adjusting the molar ratio of aniline to Fe(III). The APT/Fe3O4/PANI nanocomposites can be used as an adsorbent for the removal of dyes and the enrichment of Au(III) from the solution. In addition, the adsorbed Au(III) could be reduced to elemental gold to obtain APT/Fe3O4/PANI supported Au nanocomposites due to the good redox activities of PANI, which exhibited excellent catalytic activity toward the catalytic reduction of 4-nitrophenol in the presence of NaBH4.
Co-reporter:Yian Zheng and Aiqin Wang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 32) pp:NaN16559-16559
Publication Date(Web):2012/06/25
DOI:10.1039/C2JM32774K
A granular hydrogel based on chitosan (CTS) and acrylic acid (AA) was prepared using Fenton’s reagent as the redox initiator and N,N′-methylenebisacrylamide as the crosslinker under ambient conditions. The resulting three-dimensional (3D) networks can serve as micro- or nano-reactors for the production of highly stable silver nanoparticles by the in situ reduction of silver nitrate (AgNO3) with sodium borohydride (NaBH4) as reducing agent and Al3+ as surface crosslinking agent. The as-prepared Ag-entrapped hydrogel was successfully confirmed by means of Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA), and then tested to catalyze the NaBH4 reduction of two organic dyes: methylene blue (MB) and Congo red (CR). The catalytic results indicate that within 30 min, MB and CR with an initial concentration of 20 mg L−1 can be reduced completely, and the catalytic activity is independent of initial pH and ion strength. In addition, the Ag-entrapped hydrogel shows excellent reusability for ten successive cycles, with no appreciable decrease in the catalytic effects.
Co-reporter:Bin Mu, Wenbo Zhang, Shijun Shao and Aiqin Wang
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 17) pp:NaN7880-7880
Publication Date(Web):2014/02/27
DOI:10.1039/C4CP00280F
The graphene–MnO2–polyaniline (rGO–MnO2–PAn) ternary composites were prepared via in situ chemical oxidative polymerization of polyaniline on the MnO2 decorated graphene sheets. The graphene sheets were treated with KMnO4 in a water–ethylene glycol system using the hydrothermal method to complete the loading of MnO2 on the graphene sheets, while the graphene oxide (GO) sheets were hydrothermally reduced to reduced graphene oxide (rGO). The glycol was introduced as a reductant to react with MnO4−, and GO was protected from consumption in the process of deposition of MnO2. The structures and morphologies of the resulting ternary composites are characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of the composites as potential electrode materials for supercapacitors were investigated using different electrochemical techniques including cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS). The specific capacitance of a rGO–MnO2–PAn composite electrode was 395 F g−1 at 10 mA cm−2 in 1 M H2SO4 solution. The composites displayed good cycle stability retaining 92% of their original specific capacitance after 1200 cycles by continuous cyclic voltammetric scans at 100 mV s−1.
Co-reporter:Bin Mu, Qin Wang and Aiqin Wang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 24) pp:NaN7090-7090
Publication Date(Web):2013/05/10
DOI:10.1039/C3TA10658F
A magnetic attapulgite nanocomposite grafted crosslinked copolymer (CPSA@MATP) has been prepared via a “grafting from” technique for the adsorption of Ag+. The results show that the adsorption rate reaches 95% at pH 3 and 80% at 1% NaCl with a 1 mg mL−1 initial concentration of Ag+, respectively. The subsequent treatment of Ag+-loaded CPSA@MATP with NaBH4 leads to chemical reduction of the Ag+ to obtain Ag nanoparticle decorated CPSA@MATP (CPSA@MATP/AgNP). The catalytic activity of the CPSA@MATP/AgNP nanocomposite for the reduction of 4-nitrophenol with NaBH4 is tracked by UV-vis spectroscopy. It is suggested that CPSA@MATP/AgNP exhibits excellent catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by NaBH4. Furthermore, MATP@CPSA/AgNP can be easily recycled due to its magnetism. Therefore, the CPSA@MATP nanocomposite has a great potential application in the adsorption of trace precious metal ions, and further can be used as recyclable and low-cost catalytic materials in the area of catalytic reduction due to the high catalytic activity of precious metal nanoparticles and the superparamagnetism of Fe3O4 in the future.
Co-reporter:Bin Mu, Yuru Kang and Aiqin Wang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 15) pp:NaN4811-4811
Publication Date(Web):2013/02/11
DOI:10.1039/C3TA01620J
By the layer-by-layer self-assembly of chitosan and cysteine modified β-cyclodextrin on the surface of Fe3O4 nanoparticle-decorated attapulgite, the polyelectrolyte-coated magnetic attapulgite composite (Fe3O4/ATP@(CS/Cys-β-CD)8) was prepared for the adsorption of precious metals. The as-synthesized Fe3O4/ATP@(CS/Cys-β-CD)8 composite was characterized by zeta potential measurements, Fourier transform infrared spectroscopy, X-ray diffraction and vibrating sample magnetometry. The Fe3O4/ATP@(CS/Cys-β-CD)8 composite has an adsorption yield of about 90% for Ag+, 90% for Pd2+ and 60% for Pt4+. Moreover, it was found that the adsorption of Ag+ and Pd2+ was preferential to that of Pt4+. The results of X-ray photoelectron spectroscopy indicated that the precious metals accept electrons provided by the N, O or S atoms of the Fe3O4/ATP@(CS/Cys-β-CD)8 composite during the process of adsorption. Therefore, the Fe3O4/ATP@(CS/Cys-β-CD)8 composite is a promising recyclable and low-cost adsorbent for the adsorption of trace precious metal ions.
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![Propanedioic acid,2-[(4-methoxyphenyl)methylene]-, 1,3-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)ester](http://img.cochemist.com/ccimg/147800/147783-69-5_b.png)
