Co-reporter:Tao Xu;Qinghan Meng;Qiang Fan;Meng Yang;Wanyuan Zhi
Chinese Journal of Chemistry 2017 Volume 35(Issue 10) pp:1575-1585
Publication Date(Web):2017/10/01
DOI:10.1002/cjoc.201700190
Binder-free, nano-sized needlelike MnO2-submillimeter-sized reduced graphene oxide (nMnO2-srGO) hybrid films with abundant porous structures were fabricated through electrophoretic deposition and subsequent thermal annealing at 500 °C for 2 h. The as-prepared hybrid films exhibit a unique hierarchical morphology, in which nMnO2 with a diameter of 20—50 nm and a length of 300—500 nm is randomly anchored on both sides of srGO. When evaluated as binder-free anodes for lithium-ion half-cell, the nMnO2-srGO composites with a content of 76.9 wt% MnO2 deliver a high capacity of approximately 1652.2 mA•h•g−1 at a current density of 0.1 A•g−1 after 200 cycles. The high capacity remains at 616.8 mA•h•g−1 (ca. 65.1% capacity retention) at a current density as high as 4 A•g−1. The excellent electrochemical performance indicates that the nMnO2-srGO hybrid films could be a promising anode material for lithium ion batteries (LIBs).
Co-reporter:Caili Zhang, Pei Li, Bing Cao
Journal of Membrane Science 2017 Volume 528(Volume 528) pp:
Publication Date(Web):15 April 2017
DOI:10.1016/j.memsci.2017.01.008
•Synthesize two carboxylic acid-containing diamines and polyimides based on them.•Polyimides greatly increased gas permeability without losing selectivity.•6FDA-CADA1-425 polyimide has separation performance over 2008 Robeson Upper bound.Two carboxylic acid containing diamines, CADA1 and CADA2, with or without bulky CF3 group were synthesized and polymerized with 6FDA, BTDA and DSDA to form four polyimides, denoted as 6FDA-CADA1, 6FDA-CADA2, BTDA-CADA1 and DSDA-CADA1. After the thermal induced decarboxylation crosslink reaction, polyimides with 100 times’ higher CO2 permeabilities, similar CO2/CH4 selectivities and much better plasticization resistant properties were obtained compared with the un-crosslinked polyimides. The polymer d-spacing increased with the heating temperature and those of the fully crosslinked polyimides, 6FDA-CADA1-450 and DSDA-CADA1-450, were 5.81 Å and 5.51 Å, respectively, which were very close to the estimated distance between the crosslinked polymer chains (5.57 Å, calculated by Material Studio). The CO2-induced plasticization phenomenon was not observed at a CO2 pressure up to 30 atm for polyimides after thermally treated at temperatures above 425 °C. Moreover, polyimides crosslinked at different temperatures had almost the same selectivities, but their permeabilities gradually increased with the crosslinking temperature. For CO2/CH4 gas pair, the separation performances of 6FDA-CADA1-425 and BTDA-CADA1-450 membranes surpassed the “2008 Robeson Upper Bound”, and other membranes thermally treated at 400 and 425 °C were all positioned near the “1991 Robeson Upper Bound”.Download high-res image (178KB)Download full-size image
Co-reporter:Qian Nan, Pei Li, Bing Cao
Applied Surface Science 2016 Volume 387() pp:521-528
Publication Date(Web):30 November 2016
DOI:10.1016/j.apsusc.2016.06.150
Highlights
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Graphene oxide and polyethylenimine layer-by-layer assembly membranes.
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The deposition of PEI increases the membrane surface charge.
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Membranes with high salt rejection and flux were obtained.
Co-reporter:Jianqiang Wang;Keying Song;Li Li;Kai Pan
Journal of Chemical Technology and Biotechnology 2016 Volume 91( Issue 3) pp:777-785
Publication Date(Web):
DOI:10.1002/jctb.4644
Abstract
BACKGROUND
Polyimide (PI) solvent-resistant nanofiltration (SRNF) membranes were prepared by a two-step method. The polyamic acid (PAA) precursor was synthesized first, and then PAA membranes were obtained via a non-solvent induced phase separation method. Finally, the PAA membranes were transformed into PI membranes by the thermal imidization method. The effect of molecular weight of precursor on the structure and performance of PI membranes was investigated in detail. In addition, the influence of other processing parameters, such as evaporation time and immersion time in the coagulation bath, on the performance of PI membranes prepared from PAA with different molecular weights was also investigated.
RESULTS
The results showed that the structure of PI membrane varied with PAA molecular weight. The PI membranes prepared from low molecular weight PAA failed to form a defect-free membrane with enough strength, and resulted in high flux but low rejection. Accordingly, PI membranes processed from PAA with high molecular weight retain rejection higher than 90% of FCF with decreased flux. The results also indicated that the optimized molecular weight of PAA should be between 1.23 × 105 g mol−1 and 2.44 × 105 g mol−1 to prepare defect-free PI membrane for nanofiltration. The results also showed that the performance of the PI membranes can be controlled by adjusting the evaporation time, immersion time, and also the operating pressure.
CONCLUSIONS
The PAA molecular weight has a great effect on the morphology and performance of PI membranes. A suitable PAA molecular weight is necessary for preparing defect-free PI nanofiltration membrane. © 2015 Society of Chemical Industry
Co-reporter:Caili Zhang, Pei Li, and Bing Cao
Industrial & Engineering Chemistry Research 2016 Volume 55(Issue 17) pp:5030-5035
Publication Date(Web):April 8, 2016
DOI:10.1021/acs.iecr.6b00206
A dual-scale roughness structure superhydrophobic–superoleophilic fabric was fabricated by first etching the microscale fibers with alkali and then dip-coating in a mixed solution of a polymer of intrinsic microporosity (PIM-1) and fluorinated alkylsilane (PTES). Scanning electron microscopy analysis showed that the etching process created nanoscale pits on the fiber surface and subsequently formed hierarchical structures on the fabric surface. Coating of PIM-1–PTES on the etched fibers significantly lowered the surface energy of the fibers, thus causing the fabric surface to possess superhydrophobicity with a water contact angle of 158° and superoleophilicity with an oil contact angle of 0°. The obtained superwettable fabric was mounted in a leak-proof manner on the open-end glass bottle, like an oil skimmer container. Such a new surface-tension-driven, gravity-assisted, one-step, oil–water separation device was used to separate the oil–water mixture with a separation efficiency as high as 99.96% after 30 recycles.
Co-reporter:Caili Zhang;Pei Li
Journal of Applied Polymer Science 2016 Volume 133( Issue 22) pp:
Publication Date(Web):
DOI:10.1002/app.43475
ABSTRACT
The smooth and uniform polymer of intrinsic microporosity (PIM-1) fibers, which have high adsorption capacities toward organic contaminants from nonaqueous systems, were successfully obtained by electrospinning. According to the N2 adsorption–desorption analysis, the surface area of the PIM-1 fibers was higher than that of the PIM-1 powder. The higher surface area of the fibers did not come from the interfiber pores but from intrafiber pores formed by the fast evaporation of the solvent in the electrospinning process. The PIM-1 fibers had more mesopores than the PIM-1 films. As a result, the adsorption rates of the dyes on the fibers were much higher than those on the dense films. We found that the adsorption data fitted perfectly with the pseudo-second-order model and intraparticle diffusion model. The adsorption mechanism between the dyes and PIM-1 was π–π interaction. Therefore, the dye could be desorbed from PIM-1 with toluene; this was a better π-electron-rich donor than the dye. In summary, we believe that the use of PIM-1 fibers for organic solvent recovery is a green, sustainable, and efficient method, and they have a great potential for industrial applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43475.
Co-reporter:Bin Liang, Wu Zhan, Genggeng. Qi, Sensen Lin, Qian Nan, Yuxuan Liu, Bing Cao and Kai Pan
Journal of Materials Chemistry A 2015 vol. 3(Issue 9) pp:5140-5147
Publication Date(Web):20 Jan 2015
DOI:10.1039/C4TA06573E
As an emerging technology, pervaporation (PV) has shown great promise in fresh water production from salty water. However, the low separation efficiencies of the present membranes hinder their practical applications. Here, thin graphene oxide (GO) films with 2D nanochannels were fabricated on polyacrylonitrile (PAN) ultrafiltration membranes using a vacuum filtration-assisted assembly method. The GO/PAN composite membrane exhibits a high water flux of up to 65.1 L m−2 h−1 with high rejection (about 99.8%) for desalination by pervaporation at 90 °C. It is noteworthy that the composite membranes show high performances in treating high-salinity water, even at salt concentrations of up to 100000 ppm. This makes it possible to use GO-based membranes for seawater desalination, brackish water desalination and reverse osmosis concentrate treatment.
Co-reporter:Tao Xu, Qinghan Meng, Tianze Shen and Bing Cao
RSC Advances 2015 vol. 5(Issue 90) pp:73737-73741
Publication Date(Web):24 Aug 2015
DOI:10.1039/C5RA12901J
High-quality graphene oxide (GO) was synthesized in two steps. First, graphite on the anode was expanded in an aqueous sulfuric acid solution at a constant direct-current power supply, then it is used to synthesize GO by an improved Hummers method. The synthesized GO had a low layer number (less than five layers) and large lateral size (at least 300 μm).
Co-reporter:Caili Zhang, Pei Li, and Bing Cao
Industrial & Engineering Chemistry Research 2015 Volume 54(Issue 35) pp:8772-8781
Publication Date(Web):August 24, 2015
DOI:10.1021/acs.iecr.5b02321
A series of PIM-1/POSS microfibrous membranes were fabricated by electrospinning technology. The addition of POSS particles could greatly enhance the hydrophobicity, and a superhydrophobic–superoleophilic membrane was obtained as the POSS concentration increased to 40 wt %. The scanning electron microscopy images indicate that the incorporation of POSS particles results in formations of hierarchical structures on the surface of the PIM-1/POSS fibers. Both the intrinsic hydrophobic nature of POSS and the increase in the fiber surface roughness led to the superhydrophobicity and superoleophilicity. The 40 wt % PIM-1/POSS fibrous membrane could not only separate a wide range of immiscible oil–water mixtures with efficiencies higher than 99.95% but also separate water-in-oil emulsions with efficiencies higher than 99.97%. Furthermore, because of the ultrahigh intrinsic microporosity of the PIM-1 polymer, the PIM-1 fibrous membrane exhibited the ability to adsorb a large amount of contaminants such as oil red O and solvent blue 35 from oils. Therefore, these membranes are multifunctional and can be applied to treating immiscible water–oil mixtures, water-in-oil emulsions, and cleanup of oil soluble contaminants.
Co-reporter:Kai Pan;Haizhu Li;Bin Liang;Genggeng Qi
Polymer International 2015 Volume 64( Issue 1) pp:138-145
Publication Date(Web):
DOI:10.1002/pi.4772
Abstract
A versatile method is described to synthesize a new family of solvent-responsive membranes whose response states can be not only tunable but also fixable via ultraviolet (UV) irradiation induced crosslinking. The atom transfer radical polymerization (ATRP) initiator 2-bromoisobutyryl bromide was first immobilized on the poly(ethylene terephthalate) (PET) track-etched membrane followed by room-temperature ATRP grafting of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(2-hydroxyethyl methacrylate-co-2-(dimethylamino)ethyl methacrylate) (P(HEMA-co-DMAEMA)) respectively. The hydroxyl groups of PHEMA were further reacted with cinnamoyl chloride (a photosensitive monomer) to obtain photo-crosslinkable PET-g-PHEMA/CA membrane and PET-g-P(HEMA/CA-co-DMAEMA) membrane. The length of grafted polymer chains was controllable by varying the polymerization time. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy in attenuated total reflection and thermogravimetric analysis were employed to characterize the resulting membranes. The various membrane surface morphologies resulting from different states of the grafted chains in water and dimethylformamide were characterized by scanning electron microscopy. It was demonstrated that the grafted P(HEMA/CA-co-DMAEMA) chains had more pronounced solvent responsivity than the grafted PHEMA/CA chains. The surface morphologies of the grafted membranes could be adjusted using different solvents and fixed by UV irradiation crosslinking. © 2014 Society of Chemical Industry
Co-reporter:Bilal Khalid, Qinghan Meng, Jitao Li, Bing Cao
Electrochimica Acta 2014 Volume 142() pp:101-107
Publication Date(Web):1 October 2014
DOI:10.1016/j.electacta.2014.07.102
A new nitrogen rich porous graphene-cross-linked melamine formaldehyde carbon cryogel (GCMFCC) was successfully prepared by a sol-gel poly condensation reaction catalyzed by Na2CO3; it was subsequently converted to a cryogel by freeze-drying. The melamine formaldehyde carbon cryogel (MFCC) and GCMFCC-x were synthesized and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). XPS and BET analysis showed that the as- prepared GCMFCC-5% cryogel had a highest nitrogen content of 14.29% with surface area of 261.33 m2/g and unimodal meso-pore volume of 0.36 cm3/g. The electrochemical behavior of MFCC and GCMFCC-x samples was investigated by cyclic voltammetry and charge/discharge cycles. GCMFCC-5% achieved highest capacitance of 313.24 F/g. Hence, GCMFCC is a promising electric double-layer capacitor material with low production costs and the ability to avoid supercritical drying.
Co-reporter:Lei Wang, Kai Pan, Li Li, and Bing Cao
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 15) pp:6401-6408
Publication Date(Web):March 11, 2014
DOI:10.1021/ie4042388
The hydrophilic polyvinylidene fluoride (PVDF) material was prepared by ozone-induced grafting polymerization of acrylic acid on PVDF chains, and used for preparing oil/water separation ultrafiltration membranes by the nonsolvent induced phase separation method. The effect of membrane casting conditions was studied, and the results showed that N-methyl-2-pyrrolidone (NMP) present in the coagulation bath affected the membrane surface hydrophilicity as well as the membrane structure, and that casting solution concentration and air exposure time affected pore size but had little influence on surface hydrophilicity. The effect of material hydrophilicity and pore size was investigated, and the results indicated that improvement in hydrophilicity not only increased water flux itself, but also enabled high oil retention of membranes with larger pore sizes which had much higher water flux. The highest flux for the membranes with kerosene retention over 90% can reach over 300 L/m2h. The membranes showed good reusability under simple back flush.
Co-reporter:Ting Qu, Kai Pan, Li Li, Bin Liang, Lei Wang, and Bing Cao
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 19) pp:8228
Publication Date(Web):April 28, 2014
DOI:10.1021/ie5012905
The morphology and crystallization properties of poly(vinylidene fluoride) ultrafiltration membranes prepared by the phase inversion method were investigated under ultrasound-assisted conditions in a coagulation bath. All the membranes showed improved performance compared with that of the pristine membrane, including preferable morphology, higher porosity, and higher flux for water and a Rose Bengal (RB) aqueous solution. With an increase in the ultrasonic intensity, the flux of membranes for both water and RB aqueous solution increased gradually, while the rejection by all membranes was nearly 80%. The porosity was measured by the percentage water content. Phase separation was accelerated and macrovoids developed with an increase in ultrasonic intensity, resulting in an improvement in membrane porosity. The crystalline structure was assessed by wide-angle X-ray diffractometry and attenuated total reflectance Fourier transform infrared spectroscopy. It was also shown that the β crystalline phase was partly converted to the α crystalline phase in the ultrasound-assisted phase inversion process. Membranes prepared by ultrasound-assisted phase inversion exhibited elongation greater than that of the pristine membrane.
Co-reporter:Jianqiang Wang, Chao Luo, Genggeng Qi, Kai Pan, Bing Cao
Applied Surface Science 2014 Volume 316() pp:245-250
Publication Date(Web):15 October 2014
DOI:10.1016/j.apsusc.2014.07.198
Highlights
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PAN/PPy core/shell nanofiber used for Cr(VI) removal.
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Adsorption mechanisms were investigated.
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Selective adsorption performances were investigated.
Co-reporter:Kai Pan;Ruimin Ren;Bin Liang;Li Li;Haizhu Li
Journal of Applied Polymer Science 2014 Volume 131( Issue 20) pp:
Publication Date(Web):
DOI:10.1002/app.40912
ABSTRACT
pH-responsive polyethylene terephthalate (PET) track-etched membranes were synthesized by grafting 2-hydroxyethyl-methacrylate (HEMA) on the surface of the membrane via atom transfer radical polymerization. The controllability of grafting polymerization of HEMA on membrane surface is systematically investigated. The pH-responsive characteristics of PET-g-poly(2-hydroxyethyl-methacrylate) (PHEMA) gating membranes with different grafted PHEMA chain lengths are measured by tracking the permeation of water solution with different pH values. The results show that the grafting polymerization is controllable, and the permeation of grafted membranes is affected by the grafted PHEMA chain lengths on the surface of membrane. The results also demonstrate that the grafted PET membranes exhibit reversible pH-response permeation to environmental pH values. Desired pH-responsive membranes are obtained by controlling the grafted PHEMA chain lengths via atom transfer radical polymerization method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40912.
Co-reporter:Jianqiang Wang, Kai Pan, Emmanuel P. Giannelis and Bing Cao
RSC Advances 2013 vol. 3(Issue 23) pp:8978-8987
Publication Date(Web):18 Mar 2013
DOI:10.1039/C3RA40616D
Polyacrylonitrile/polyaniline core/shell nanofibers were prepared via electrospinning followed by in situ polymerization of aniline. Nanofibers with different morphology were obtained by changing the polymerization temperature. When used as absorbent for Cr(VI) ions, the core/shell nanofiber mats exhibit excellent adsorption capability. The equilibrium capacity is 24.96, 37.24, and 52.00 mg g−1 for 105, 156, and 207 mg L−1 initial Cr(VI) solution, respectively, and the adsorption capacity increases with temperature. The adsorption follows a pseudo second order kinetics model and is best fit using the Langmuir isotherm model. The mats show excellent selectivity towards Cr(VI) ions in the presence of competing ions albeit a small decrease in adsorption is observed. The mats can be regenerated and reused after treatment with NaOH making them promising candidates as practical adsorbents for Cr(VI) removal.
Co-reporter:Kai Pan;Ruimin Ren;Haizhu Li
Polymers for Advanced Technologies 2013 Volume 24( Issue 1) pp:22-27
Publication Date(Web):
DOI:10.1002/pat.3044
A dual stimuli-responsive (pH and thermo) polyethylene terephthalate (PET) track-etched membrane has been prepared using atom transfer radical polymerization (ATRP). First, ATRP initiator 2-bromoisobutyryl bromide was anchored onto the membrane surface. Then, 2-hydroxyethyl-methacrylate (HEMA) and N-isopropylacrylamide (NIPAAm) were grafted onto the membrane surface using ATRP. X-ray photoelectron spectroscopy, ATR-Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis were used to characterize the membrane structure and thermal properties; water flux measurement was used to investigate the double stimuli-responsive property of the obtained membrane. The results indicate that the PHEMA and PNIPAAm binary grafted PET track-etched membrane has double environmental responsiveness. This method provides a potential modification method for preparing functional membranes. Copyright © 2012 John Wiley & Sons, Ltd.
Co-reporter:Qinghan Meng;Xingchao Li;Ling Liu
Journal of Materials Science 2012 Volume 47( Issue 16) pp:5926-5932
Publication Date(Web):2012 August
DOI:10.1007/s10853-012-6495-y
TiO2 anatase phase-mounted carbon aerogels (CAs) were synthesized via the sol–gel polymerization of a mixture of resorcinol, formaldehyde, and tetrabutyl orthotitanate, followed by gelation, supercritical drying, and carbonization in N2 atmosphere. Ethanol was selected as the solvent in the sol–gel polymerization process. The morphology and microstructural characteristics of the TiO2-mounted carbon aerogel sample were obtained using thermogravimetry, transmission electron microscopy, scanning electron microscopy, N2 adsorption–desorption, and X-ray diffraction methods. The total pore volume and average pore sizes increased with TiO2 addition. Titania phase in anatase form was found to be more homogeneously distributed in the CAs at 900 °C. The anatase–rutile transformation did not take place at carbonization temperatures from 500 to 1100 °C and cyclic voltammetry measurements showed that the TiO2-mounted CAs exhibit good reversibility and high specific capacity as electrode materials, and the anatase in the carbon structure were not involved in the redox reactions. Electrochemical impedance spectroscopy demonstrated that the CA electrode behaves as an excellent capacitor with low resistance.
Co-reporter:Xingchao Li;Ling Liu;Qinghan Meng
Journal of Applied Electrochemistry 2012 Volume 42( Issue 4) pp:249-255
Publication Date(Web):2012 April
DOI:10.1007/s10800-012-0391-7
TiO2-doped carbon aerogels (CAs) were synthesized by sol–gel polymerization of a mixture of resorcinol, formaldehyde and tetrabutyl orthotitanate, followed by gelation and supercritical drying and carbonization in N2 gas atmosphere. The morphology of these TiO2-doped CAs was characterized by transmission electron microscopy. X-ray diffraction and Brunauer–Emmett–Teller methods were employed to determine the microstructure and surface characteristics of samples. It was found that the doped TiO2 had no significant effect on the surface area of the samples, whereas the pore and mesopore volumes were increased by the addition of TiO2. The TiO2 particles were kept still as anatase in samples carbonized at 900 °C, and did not transform into rutile on heating. Electrochemical performance of the samples as electrode materials was studied by cyclic voltammetry, electrochemical impedance spectroscopy, and constant current charge/discharge measurements. The results showed that the specific capacitance of CA electrodes had been improved by TiO2 doping, and the samples with wider pore diameters have higher capacitance values.
Co-reporter:Zhenyu Zhao, Qinghan Meng, Peijin Li, Bing Cao
Electrochimica Acta 2011 Volume 56(Issue 3) pp:1094-1098
Publication Date(Web):1 January 2011
DOI:10.1016/j.electacta.2010.07.080
We develop a novel method of synthesizing 2,2′-dichlorohydrazobenzene (DHB) from o-chlornitrobenzene (o-CNB) in a membrane-separated cell on a porous Ni/Fe-combined electrode. PbO particles are used as a catalyst and are dispersed finely over and in the electrode surface. The morphology and microstructure characteristics of electrode materials are characterized by SEM and XRD analyses. The influences of the cathodic surface morphology, electrolyte temperature, and initial concentration of o-CNB are investigated by liquid chromatography and electrochemistry. A moderate current density (e.g., 5.2 A/dm2) and temperature (70 °C) are beneficial to improving hydrogenation reduction, current efficiency, and yield, which could reach 85% when density is adjusted and 91% when the temperature is adjusted.
Co-reporter:Kai Pan;Ruimin Ren;Yi Dan
Journal of Applied Polymer Science 2011 Volume 122( Issue 3) pp:2047-2053
Publication Date(Web):
DOI:10.1002/app.34265
Abstract
Controlled thermoresponsive PET track-etched membranes were synthesized by grafting N-isopropylacrylamide (NIPAAm) onto the membrane surface via atom transfer radical polymerization (ATRP). The initial measurements were made to determine the anchoring of ATRP initiator on PET membrane surface. Thereafter, polymerization was carried out to control the mass of polymer by controlling reaction time grafted from the membrane surface and, ATR-FTIR, grafting degree measurements, water contact angle measurements, TGA, and SEM were used to characterize changes in the chemical functionality, surface and pore morphology of membranes as a result of modification. Water flux measurements were used to evaluate the thermoresponsive capacity of grafted membranes. The results show the grafted PET track-etched membranes exhibit rapid and reversible response of permeability to environmental temperature, and its permeability could be controlled by controlling polymerization time using ATRP method. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.
Co-reporter:Kai Pan, Xiaowei Zhang, Ruimin Ren, Bing Cao
Journal of Membrane Science 2010 Volume 356(1–2) pp:133-137
Publication Date(Web):1 July 2010
DOI:10.1016/j.memsci.2010.03.044
Double stimuli-responsive regenerated cellulose membranes have been prepared using atom transfer radical polymerization (ATRP) method. Firstly, the ATRP initiator of 2-bromoisobutyryl bromide was anchored on the surface of regenerated cellulose membranes. Then acrylic acid (AAc) and N-isopropylacrylamide (NIPAAm) were grafted onto the membrane surface step by step using ATRP method. The grafted chain length could be controlled by polymerization time. The uniform chain length could make the grafted copolymer (P(AAc)-b-P(NIPAAm)) as clear and different aggregate phase. So, the double stimuli-responsive property of block copolymer grafted membrane was distinct. Also, the results showed that the stimuli-responsive property of membrane was not a simple adding of two different stimuli-responsive properties, such as pH-responsive and thermo-responsive but more complicated responses to the changes of pH values and temperatures because of the reciprocity of different molecules. In this paper, the membrane was characterized by XPS, ATR-FTIR, TGA and SEM. The double stimuli-responsive properties of grafted membranes were measured by water flux measurement.
Co-reporter:Wen-Cai Wang;Jin Wang;Yuan Liao;Liqun Zhang;Guojun Song;Xilin She
Journal of Applied Polymer Science 2010 Volume 117( Issue 1) pp:534-541
Publication Date(Web):
DOI:10.1002/app.30939
Abstract
A facile method for surface-initiated atom transfer radical polymerization (ATRP) on the anodic aluminum oxide (AAO) membranes has been developed. The AAO membrane was firstly functionalized by poly(dopamine), the bromoalkyl initiator was then immobilized on the poly(dopamine) functionalized AAO membrane surface in a two-step solid-phase reaction, followed by ATRP of acrylic acid in a aqueous solution. The poly(acrylic acid) (PAAc)-grafted AAO membranes were characterized by X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy and scanning electron microscopy. The XPS and FTIR results indicated that PAAc was successfully grafted on the AAO membrane surface. The degree of grafting increases linearly with the increase of monomer concentration, and it reaches a plateau when the reaction time up to 4 h. The results indicate that the thickness of the grafted polymer inside the isocylindrical pores of AAO membranes could be well controlled by changing the reaction time and monomer concentration. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Jianqiang Wang, Tianjie Wang, Li Li, Peixin Wu, Kai Pan, Bing Cao
Journal of Water Process Engineering (September 2014) Volume 3() pp:98-104
Publication Date(Web):1 September 2014
DOI:10.1016/j.jwpe.2014.05.015
Poly(glycidyl methacrylate-t-N-methyl-d-glucamine) (P(GMA-t-NMDG)) functionalized polyacrylonitrile (PAN) nanofibers were prepared via electrospinning followed by surface modification. The functionalized PAN nanofiber mat was used for boric acid removal from aqueous solutions. Attenuated total reflections Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) results confirmed the presence of vicinal polyalcohol groups on the surface of these nanofibers. Surface morphology of PAN-P(GMA-t-NMDG) nanofiber mat was studied by SEM. The analysis results from inductively coupled plasma mass spectrometry show that the boron adsorption process is pH-dependent with a maximum adsorption removal ratio at a pH value of 6.0–7.0. The as-functionalized PAN-P(GMA-t-NMDG) nanofiber mat is very effective for boric acid removal at extremely low concentrations which may find the potential application for further boric acid removal from the RO permeates. Meanwhile, the PAN-P(GMA-t-NMDG) nanofiber mat also demonstrates outstanding reusability.
Co-reporter:Kai Pan, Peng Fang, Bing Cao
Desalination (15 May 2012) Volume 294() pp:36-43
Publication Date(Web):15 May 2012
DOI:10.1016/j.desal.2012.03.007
Interfacial polymerization (IP) is a powerful technique for the fabrication of thin film composite (TFC) membranes. In this work, porous polypropylene fiber films were used as a support to fabricate TFC nanofiltration membrane using IP technique. Firstly, the surface of polypropylene fiber film was hydrophilized by introducing peroxide onto the membrane surface using ozone treatment followed by grafting acrylamide. And then interfacial polymerization could be successfully proceeding on the hydrophilized PP membrane. The monomeric system chosen for IP was m-phenylenediamine (MPDA) and trimesoyl chloride (TMC). The ozone treatment time was investigated, and in the range of 5–10 min ozone treatment time, the PP fiber membrane had an available amount of peroxides for grafting while keeping the mechanical strength. The characteristics of the original membrane, grafted membrane and TFC membrane were studied with various analytical methods, such as SEM and FTIR-ATR. Meanwhile, the nanofiltration performance was evaluated with aqueous solutions of Na2SO4 (2 g/L) and Fast Green FCF (MW 808.84, 10 mg/L). The rejection rate of 60% and 90% were achieved for Na2SO4 and Fast Green FCF, respectively, at a transmembrane pressure of 0.5 MPa.Highlights► Hydrophilic modification of PP membrane. ► Thin film composite NF membrane by interfacial polymerization on PP support. ► Hydrophilicity of the support is the main factor.
Co-reporter:Bin Liang, Kai Pan, Li Li, Emmanuel P. Giannelis, Bing Cao
Desalination (15 August 2014) Volume 347() pp:199-206
Publication Date(Web):15 August 2014
DOI:10.1016/j.desal.2014.05.021
•A novel facile method for preparing pervaporation composite membranes•Pervaporation composite membrane for water desalination with high flux•Relationship between top dense layer thickness and mass transfer efficiencyA three-layer thin film nanofibrous pervaporation composite (TFNPVC) membrane was prepared by sequential deposition using electrospraying/electrospinning. The poly(vinyl alcohol) (PVA) top barrier layer was first electrosprayed on aluminum foil and its thickness can be easily controlled by adjusting the collecting time. Next a polyacrylonitrile (PAN) nanofibrous scaffold was deposited by electrospinning as a mid-layer support. A nonwoven PET layer is used to complete the composite membrane. The pervaporation desalination performance of TFNPVC membranes was tested using NaCl solutions at 100 Pa and at room temperature. The TFNPVC membranes show excellent desalination performance (high water flux and salt rejection > 99.5%) for different salt concentrations with virtually no change in performance after 50 h of operation.
Co-reporter:Bin Liang, Wu Zhan, Genggeng. Qi, Sensen Lin, Qian Nan, Yuxuan Liu, Bing Cao and Kai Pan
Journal of Materials Chemistry A 2015 - vol. 3(Issue 9) pp:NaN5147-5147
Publication Date(Web):2015/01/20
DOI:10.1039/C4TA06573E
As an emerging technology, pervaporation (PV) has shown great promise in fresh water production from salty water. However, the low separation efficiencies of the present membranes hinder their practical applications. Here, thin graphene oxide (GO) films with 2D nanochannels were fabricated on polyacrylonitrile (PAN) ultrafiltration membranes using a vacuum filtration-assisted assembly method. The GO/PAN composite membrane exhibits a high water flux of up to 65.1 L m−2 h−1 with high rejection (about 99.8%) for desalination by pervaporation at 90 °C. It is noteworthy that the composite membranes show high performances in treating high-salinity water, even at salt concentrations of up to 100000 ppm. This makes it possible to use GO-based membranes for seawater desalination, brackish water desalination and reverse osmosis concentrate treatment.
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![POLY[OXY-1,4-PHENYLENEIMINOCARBONYL(DICARBOXYPHENYLENE)CARBONYLIMINO-1,4-PHENYLENE]](http://img.cochemist.com/ccimg/9100/9043-05-4.png)
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