Co-reporter:Weibing Xu;Bin Mu;Aiqin Wang
Cellulose 2017 Volume 24( Issue 12) pp:5579-5592
Publication Date(Web):05 October 2017
DOI:10.1007/s10570-017-1505-5
The various morphologies of polyaniline are grown on carbon fibers derived from natural hollow cellulose by in situ polymerization of aniline. The morphologies of nanofibers, pyramid-like, nanorods and nanowires can be facilely controlled by the doping of hydrochloric acid, sulfuric acid, perchloric acid, phosphoric acid and p-toluenesulfonic acid, respectively. The perchloric acid doped composite shown the maximum specific capacitance of 580 F g−1 at 1.0 A g−1. Remarkably, the all solid-state supercapacitors based on this sample deliver a maximum energy density of 13.3 Wh kg−1. The excellent performance is attributed to the unique morphology and hollow structure of the conductive substrate, which can drastically facilitate the ion diffusion and improve the utilization of the electroactive.
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
- •
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;Aiqin Wang
Colloid and Polymer Science 2015 Volume 293( Issue 7) pp:2009-2016
Publication Date(Web):2015 July
DOI:10.1007/s00396-015-3587-7
A granular hydrogel was prepared under ambient conditions using chitosan as the graft backbone, acrylic acid as the monomer, and ascorbic acid/hydrogen peroxide (Vc/H2O2) as the redox initiator, and then crosslinked with Fe3+ ions. The resulting Fe3+-hydrogel was tested for the catalytic reduction of 4-nitrophenol (4-NP), with the finding that in the presence of NaBH4 and an inert atmosphere, 5 mg/L 4-NP can be completely reduced by Fe3+-hydrogel within 30 min. Also, Fe3+-hydrogel exhibits an excellent reusability for ten successive catalytic cycles.
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: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: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:Jianghua Liu;Wenbo Wang;Aiqin Wang
Polymers for Advanced Technologies 2011 Volume 22( Issue 5) pp:627-634
Publication Date(Web):
DOI:10.1002/pat.1558
Abstract
A series of granulated semi-interpenetrating polymer network (semi-IPN) superabsorbent hydrogels composed of chitosan-g-poly(acrylic acid) (CTS-g-PAA) and poly(vinyl alcohol) (PVA) were prepared by solution polymerization using ammonium persulfate (APS) as an initiator and N,N′-methylenebisacrylamide (MBA) as a crosslinker. The effects of reaction conditions such as the concentration of MBA, the weight ratio of AA to CTS, and the content of PVA on water absorbency were investigated. Infrared (IR) spectra and differential scanning calorimetry (DSC) analyses confirmed that AA had been grafted onto CTS backbone, and PVA semi-interpenetrating into CTS-g-PAA networks. SEM analyses indicated that CTS-g-PAA/PVA has improved porous surface and PVA was uniformly dispersed in CTS-g-PAA network. The semi-IPN hydrogel containing 10 wt% PVA shows the highest water absorbency of 353 and 53 g g−1 in distilled water and 0.9 wt% NaCl solution, respectively. Swelling behaviors revealed that the introduction of PVA could improve the swelling rate and enhance the pH stability of the superabsorbent hydrogel. Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:J. Zhang, Q. Wang, A. Wang
Acta Biomaterialia 2010 Volume 6(Issue 2) pp:445-454
Publication Date(Web):February 2010
DOI:10.1016/j.actbio.2009.07.001
Abstract
In order to find a new way to slow down the release of drugs and to solve the burst release problem of drugs from traditionally used hydrogel matrices, a series of novel pH-sensitive sodium alginate/hydroxyapatite (SA/HA) nanocomposite beads was prepared by the in situ generation of HA micro-particles in the beads during the sol–gel transition process of SA. The SA/HA nanocomposites were characterized by Fourier transform IR spectroscopy, X-ray fluorescence spectrometry, scanning electron microscopy and field emission SEM in order to reveal their composition and surface morphology as well as the role that the in situ generated HA micro-particles play. The factors influencing the swelling behavior, drug loading and controlled release behavior of the SA/HA nanocomposite beads were also investigated using diclofenac sodium (DS) as the model drug. The HA micro-particles act as inorganic crosslinkers in the nanocomposites, which could contract and restrict the movability of the SA polymer chains, and then change the surface morphology and decrease the swell ratio. Meanwhile, the entrapment efficiency of DS was improved, and the burst release of DS was overcome. The factors (including concentration of Ca2+, reaction time and temperature) affecting the growth of HA micro-particles have a clear influence on the entrapment efficiency and release rate of DS. In this work, the nanocomposite beads prepared under optimum condition could prolong the release of DS for 8 h more compared with the pristine SA hydrogel beads.
Co-reporter:Wenbo Wang, Aiqin Wang
Carbohydrate Polymers 2010 Volume 82(Issue 1) pp:83-91
Publication Date(Web):2 August 2010
DOI:10.1016/j.carbpol.2010.04.026
Grafting vinyl monomers onto natural polysaccharides and then compounding with inorganic nano-scale clays become a preferred method to derive superabsorbents because it afforded unique environmental and commercial advantages. In current work, a series of superabsorbent nanocomposites were prepared by radical solution polymerization of sodium carboxymethyl cellulose (CMC), partially neutralized acrylic acid (NaA) and attapulgite (APT) using ammonium persulfate (APS) as an initiator and N,N′-methylenebisacrylamide (MBA) as a crosslinker. Fourier transform infrared spectroscopy (FTIR) spectra proved that NaA was grafted onto CMC backbone and APT participated in polymerization. APT nanofibrils were retained in nanocomposite and uniformly dispersed in the CMC-g–PNaA matrix as shown by X-ray diffraction (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM) analyses. The thermal stability and water absorption of the nanocomposites were improved due to the incorporation of APT. The water absorption and gel strength depends on the MBA concentration. The remarkable pH-sensitivity and time-dependent swelling behavior of the nanocomposite in aqueous solution of cetyltrimethylammonium bromide (CTAB) were observed and discussed.
Co-reporter:Yuntao Xie;Aiqin Wang;Gang Liu
Polymer Composites 2010 Volume 31( Issue 1) pp:89-96
Publication Date(Web):
DOI:10.1002/pc.20770
Abstract
In this work, a series of chitosan-g-poly(acrylic acid)/sepiolite (CTS-g-PAA/ST) superabsorbent composites containing raw sepiolite, acid-activated sepiolite, and cation-exchanged sepiolite were synthesized by free-radical graft polymerization in aqueous solution, using N,N′-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The effects of raw sepiolite, acid-activated sepiolite, and cation-exchanged sepoilite on equilibrium water absorbency, swelling rate, and swelling behavior in different pH value solution of superabsorbent composites were systematically investigated. The results from FTIR spectra showed that chitosan and sepiolite participated in graft polymerization reaction with acrylic acid. The introduction of acid-activated and cation-exchanged sepiolite into chitosan-g-poly(acrylic acid) polymeric network could improve water absorbency and swelling rate compared with that of the raw sepiolite. All prepared samples have similar swelling behavior in different pH solutions and the equilibrium water absorbencies of samples keep roughly constant in the pH range from 4 to 12. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Co-reporter:Junping Zhang;Yin Liu ;Aiqin Wang
Polymer Composites 2010 Volume 31( Issue 4) pp:691-699
Publication Date(Web):
DOI:10.1002/pc.20845
Abstract
In this work, a novel poly(acrylic acid-co-N-acryloylmorpholine)/attapulgite superabsorbent composite was prepared by graft copolymerization among acrylic acid, N-acryloylmorpholine and attapulgite in aqueous solution, using N,N′-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The result from FTIR spectra showed that OH of attapulgite participated in graft copolymerization with acrylic acid and N-acryloylmorpholine. Proper monomer ratio and atapulgite content could form a loose surface, and improve reswelling ability and initial swelling rate. The buffer action of the COOH and COO− groups in the superabsorbent composite keeps the water absorbency a rough constant in the pH range of 4.4–9.6. Both polarity and structure of an organic solvent are responsible for the phase transition point of the superabsorbent composite. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Co-reporter:Wenbo Wang;Aiqin Wang
Journal of Applied Polymer Science 2010 Volume 115( Issue 3) pp:1814-1822
Publication Date(Web):
DOI:10.1002/app.31306
Abstract
Design and synthesis of the agricultural and ecological superabsorbent materials with cost-efficient and fertilizer-release characteristics has recently attracted considerable interests. In this work, the novel poly(sodium-potassium acrylate-co-acrylamide)/plant ash (PNa-KA-co-AM/PA) superabsorbent composites with potassium-release characteristics were prepared using partially neutralized acrylic acid (Na-KA), acrylamide (AM), and plant ash (PA) as raw materials, ammonium persulfate (APS) as the initiator, and N,N′-methylenebisacrylamide (MBA) as the crosslinker. The structure, morphologies, and thermal stability of the composites were characterized by Fourier transform infrared spectrophotometer, scanning electron microscopy, and TGA techniques, respectively. The effects of MBA concentration and PA content on water absorbency were studied, and the swelling properties of the composites in saline solutions and various pHs solution as well as their potassium-release capabilities were also evaluated. Results indicate that the composites exhibit better thermal stability, salt-resistant performance, pH-stability, and potassium-release properties, and can act as a fertilizer and an effective water-saving material for agricultural and ecological application. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Jinlei Wang;Wenbo Wang;Aiqin Wang
Polymer Engineering & Science 2010 Volume 50( Issue 5) pp:1019-1027
Publication Date(Web):
DOI:10.1002/pen.21500
Abstract
In this work, a series of novel hydroxyethyl cellulose- g-poly(acrylic acid)/attapulgite (HEC-g-PAA/APT) superabsorbent composites were prepared through the graft polymerization of hydroxyethyl cellulose (HEC), partially neutralized acrylic acid (AA), and attapulgite (APT) in aqueous solution, and the composites were characterized by means of Fourier-transform spectroscopy, scanning electron microscopy, and transmission electronmicroscopy. The effects of polymerization variables including concentrations of the initiator and crosslinker and APT content on water absorbency were studied, and the swelling properties in various pH solutions as well as the swelling kinetics in various saline solutions were also systematically evaluated. Results showed that the introduction of 5 wt% APT into HEC-g-PAA polymeric network could improve both water absorbency and water absorption rate of the superabsorbent composites. In addition, the superabsorbent composites retained high water absorbency over a wide pH range of 4–10, and the swelling kinetics of the superabsorbent composites in CaCl2 and FeCl3 solutions exhibited a remarkable overshooting phenomenon. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Co-reporter:Jun-Ping Zhang;Qin Wang;Xiao-Ling Xie;Xun Li;Ai-Qin Wang
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2010 Volume 92B( Issue 1) pp:205-214
Publication Date(Web):
DOI:10.1002/jbm.b.31507
Abstract
Layered double hydroxides (LDHs) are promising materials for the preparation of novel drug delivery matrices. To reveal the interaction between LDHs and polymers, a series of pH-sensitive sodium alginate/layered double hydroxides (SA/LDHs) hybrid beads were prepared using the simple surface crosslinking method. The SA/LDHs hybrid beads were characterized by FTIR, XRD, and SEM to study their structure and the role that LDHs play. Swelling behaviors in various aqueous solutions and drug loading as well as controlled release behavior of the SA/LDHs hybrid beads were also investigated by using diclofenac sodium (DS) as the model drug to reveal the effects of introduced LDHs. The results indicate that the positively charged LDHs layers are adsorbed on the negatively charged SA polymer chains through electrostatic interaction and act as inorganic crosslinkers in the three-dimensional network. In addition, a small part of DS molecules intercalate into layers of LDHs through an anion exchange process. The electrostatic interaction between LDHs and SA has restricted movability of the SA polymer chains, and then slows down swelling and dissolution rates of the SA/LDHs hybrid beads in aqueous solutions. The electrostatic interaction and the intercalation of DS into layers of LDHs have also improved the entrapment efficiency (EE) and controlled release behavior of SA/LDHs hybrid beads for DS. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2010
Co-reporter:Wenbo Wang, Aiqin Wang
Carbohydrate Polymers 2009 Volume 77(Issue 4) pp:891-897
Publication Date(Web):19 July 2009
DOI:10.1016/j.carbpol.2009.03.012
Novel guar gum-g-poly(sodium acrylate)/rectorite (GG-g-PNaA/REC) superabsorbent nanocomposites were prepared in aqueous solution using guar gum (GG), partially neutralized acrylic acid (NaA), acidified rectorite (H+-REC) and organified rectorite (CTA+-REC) by cetyltrimethylammonium bromide (CTAB) as raw materials, ammonium persulfate (APS) as initiator and N,N′-methylenebisacrylamide (MBA) as crosslinker. FTIR spectra confirmed that NaA had been grafted onto GG chains and the OH groups of REC participated in polymerization reaction. Exfoliated nanocomposite was obtained for H+-REC and intercalated structure was formed for CTA+-REC as shown by XRD results. SEM observations show REC has been uniformly dispersed in polymeric matrix. Effects of HCl concentration, organification degree of CTA+-REC and content of REC on swelling capabilities were investigated and the swelling kinetics of nanocomposites was evaluated. Results indicate that modifying REC by acidification and organification can improve swelling properties of the resultant nanocomposites, and GG-g-PNaA/CTA+-REC exhibited higher swelling capability and swelling rate contrast to GG-g-PNaA/H+-REC.
Co-reporter:Qin Wang, Junping Zhang, Aiqin Wang
Carbohydrate Polymers 2009 Volume 78(Issue 4) pp:731-737
Publication Date(Web):17 November 2009
DOI:10.1016/j.carbpol.2009.06.010
A series of pH-sensitive composite hydrogel beads composed of chitosan-g-poly (acrylic acid)/attapulgite/sodium alginate (CTS-g-PAA/APT/SA) was prepared as drug delivery matrices crosslinked by Ca2+ owing to the ionic gelation of SA. The structure and surface morphology of the composite hydrogel beads were characterized by FTIR and SEM, respectively. pH-sensitivity of these composite hydrogels beads and the release behaviors of drug from them were investigated. The results showed that the composite hydrogel beads had good pH-sensitivity. The cumulative release ratios of diclofenac sodium (DS) from the composite hydrogel beads were 3.76% in pH 2.1 solution and 100% in pH 6.8 solutions within 24 h, respectively. However, the cumulative release ratio of DS in pH 7.4 solution reached 100% within 2 h. The DS cumulative release ratio reduced with increasing APT content from 0 to 50 wt%. The drug release was swelling-controlled at pH 6.8.
Co-reporter:Junping Zhang, Aiqin Wang
Journal of Colloid and Interface Science 2009 Volume 334(Issue 2) pp:212-216
Publication Date(Web):15 June 2009
DOI:10.1016/j.jcis.2009.03.074
Single-walled carbon nanotubes (SWNTs) were homogeneously dispersed in the aqueous solution of poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAm-co-AA)) with the assistance of sonification as evidenced by UV–vis absorption spectroscopy, transmission electron microscopy, field emission scanning electron microscopy and atomic force microscopy, etc. In addition, the SWNTs were endowed with pH- and thermo-sensitivity at the same time. The SWNTs switched reversibly between the aggregated and the well-exfoliated states by using pH or temperature as a stimulus. Moreover, the factors including solvent composition while preparing P(NIPAm-co-AA), concentration and composition of P(NIPAm-co-AA) showed evident influence on the dispersing stability of SWNTs. The introduction of a tiny amount of acrylic acid to copolymerize with N-isopropylacrylamide could greatly enhance dispersing ability of SWNTs.Single-walled carbon nanotubes can be reversibly switched between aggregated and well-exfoliated states by altering pH or temperature in the aqueous solution of poly(N-isopropylacrylamide-co-acrylic acid).
Co-reporter:Shuibo Hua, Aiqin Wang
Carbohydrate Polymers 2009 Volume 75(Issue 1) pp:79-84
Publication Date(Web):5 January 2009
DOI:10.1016/j.carbpol.2008.06.013
A novel sodium alginate-g-poly(acrylic acid)/sodium humate superabsorbent was prepared by graft copolymerization with sodium alginate, acrylic acid and sodium humate in aqueous solution, using N,N’-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The effects of crosslinker, sodium alginate and sodium humate content on water absorbency of the superabsorbent were studied. The swelling behavior in solutions of various pH and the swelling kinetics in saline solutions (5 mmol/L NaCl and CaCl2) were also investigated. The results from IR analysis showed that both sodium alginate and sodium humate react with the acrylic acid monomer during the polymerization process. The introduction of sodium humate into the sodium alginate-g-poly(acrylic acid) system could enhance the water absorbency and the superabsorbent containing 10 wt% sodium humate acquired the highest water absorbency (1380 g/g in distilled water and 83 g/g in 0.9 wt% NaCl solution).
Co-reporter:Wenbo Wang;Aiqin Wang
Journal of Applied Polymer Science 2009 Volume 112( Issue 4) pp:2102-2111
Publication Date(Web):
DOI:10.1002/app.29620
Abstract
Superabsorbents used in agricultural and ecological projects with low-cost, slow-release fertilizers and environmentally friendly characteristics have been extensively studied. The use of a natural polymer as the matrix and then further polymerization with some functional material has become the preferred method. In this work, with natural guar gum (GG), partially neutralized acrylic acid, and sodium humate (SH) as the raw materials, ammonium persulfate as the initiator, and N,N′-methylenebisacrylamide (MBA) as the crosslinker, GG-g-poly(sodium acrylate) (PNaA)/SH superabsorbents were synthesized through a solution polymerization reaction and were characterized with Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The effects of the SH content and MBA concentration on the water absorbency were investigated. The results showed that the introduction of SH into the GG-g-PNaA system could improve the water absorbency, swelling rate, pH-resistant property, and reswelling capability, and the superabsorbent containing 15 wt % SH had the highest water absorbency of 532 g/g of sample in distilled water and 62 g/g of sample in a 0.9 wt % NaCl solution. The slow release in water and water retention in sandy soil tests revealed that the superabsorbent could act as a fertilizer as well as an effective water-saving material for agricultural applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:Yian Zheng ;Aiqin Wang
Polymer Composites 2009 Volume 30( Issue 8) pp:1138-1145
Publication Date(Web):
DOI:10.1002/pc.20670
Abstract
In this work, the effects of different cation-exchanged montmorillonite on water absorbency of poly(acrylic acid-co-acrylamide)/montmorillonite/sodium humate (PAA-AM/MMT/SH) superabsorbent composite were systematically investigated under the same preparation conditions. The superabsorbents doped with different cation-exchanged montmorillonite were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy technologies. Swelling behaviors of developing superabsorbent composite in various cationic saline solutions (NaCl, CaCl2, and FeCl3) were also investigated. The water absorbencies of superabsorbent composite with 20 wt% MMT and 30 wt% SH are 638, 723, 682, and 363 g g−1 in distilled water for incorporating natural Na+-MMT, Li+-exchanged MMT, Ca2+-exchanged MMT, and Al3+-exchanged MMT, respectively. The results showed that the cation-exchange process had some obvious influences on final water absorbency of superabsorbent composite. NaCl, CaCl2, and FeCl3 solutions did not alter the swelling characteristics of the superabsorbent materials at a concentration of less than 0.01 mM, however, a concentration of greater than 0.1 mM caused a collapse in the swelling curves. The excellent swelling-reswelling-swelling behavior and lower swelling rate testified that Al3+-exchanged MMT can act as an assistant crosslinker in the polymeric network. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Co-reporter:Jianghua Liu;Yian Zheng;Wenbo Wang;Aiqin Wang
Journal of Applied Polymer Science 2009 Volume 114( Issue 1) pp:643-652
Publication Date(Web):
DOI:10.1002/app.30592
Abstract
The phosphorylated poly(vinyl alcohol) (P-PVA) samples with various substitution degrees were prepared through the esterification reaction of PVA and phosphoric acid. By using chitosan (CTS), acrylic acid (AA) and P-PVA as raw materials, ammonium persulphate (APS) as an initiator and N,N-methylenebisacrylamide as a crosslinker, the CTS-g-PAA/P-PVA semi-interpenetrated polymer network (IPN) ssuperabsorbent hydrogel was prepared in aqueous solution by the graft copolymerization of CTS and AA and followed by an interpenetrating and crosslinking of P-PVA chains. The hydrogel was characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) techniques, and the influence of reaction variables, such as the substitution degree and content of P-PVA on water absorbency were also investigated. FTIR and DSC results confirmed that PAA had been grafted onto CTS backbone and revealed the existence of phase separation and the formation of semi-IPN network structure. SEM observations indicate that the incorporation of P-PVA induced highly porous structure, and P-PVA was uniformly dispersed in the polymeric network. Swelling results showed that CTS-g-PAA/P-PVA semi-IPN superabsorbent hydrogel exhibited improved swelling capability (421 g·g−1 in distilled water and 55 g·g−1 in 0.9 wt % NaCl solution) and swelling rate compared with CTS-g-PAA/PVA hydrogel (301 g·g−1 in distilled water and 47 g·g−1 in 0.9 wt % NaCl solution) due to the phosphorylation of PVA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:Yuntao Xie;Aiqin Wang
Journal of Polymer Research 2009 Volume 16( Issue 2) pp:143-150
Publication Date(Web):2009 March
DOI:10.1007/s10965-008-9212-4
A novel chitosan-g-poly (acrylic acid)/unexpanded vermiculite (CTS-g-PAA/UVMT) superabsorbent composite was prepared by graft polymerization among chitosan (CTS), acrylic acid (AA) and unexpanded vermiculite (UVMT) in aqueous solution. The effect of polymerization variables, including the content of crosslinker, initiator and UVMT, the weight ratio of AA to CTS, the reaction temperature, time and drying method, on water absorbency were studied. The swelling rate of the superabsorbent composite in distilled water was also investigated. The results from FTIR spectra showed that CTS and UVMT participated in graft polymerization reaction with AA. Introducing UVMT into the CTS-g-PAA polymeric network could form a loose and more porous structure by the SEM analysis, and the polymerization reaction is performed on the surface of UVMT micropowders from the results of XRD. The introduced UVMT enhanced the swelling rate and the water absorbency of CTS-g-PAA/UVMT superabsorbent composite.
Co-reporter:Yian Zheng ;Aiqin Wang
Journal of Applied Polymer Science 2008 Volume 108( Issue 1) pp:211-219
Publication Date(Web):
DOI:10.1002/app.27439
Abstract
A series of novel multifunctional poly (acrylic acid-co-acrylamide) (PAA-AM)/organomontmorillonite (O-MMT)/sodium humate (SH) superabsorbent composites were synthesized by the graft copolymerization reaction of partially neutralized acrylic acid and acrylamide on O-MMT micropowder and SH with N,N′-methylene bisacrylamide as a crosslinker and ammonium persulfate as an initiator in an aqueous solution. The superabsorbent composites were characterized by means of Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The effect of the relative weight ratio of SH to O-MMT on the water absorbency was studied, and the results indicated that the best water absorbency of 591 g/g in distilled water was obtained when an O-MMT content of 20 wt % and an SH content of 30 wt % were incorporated. The superabsorbent composite possessed a good capacity for water retention; even after 30 days, 24.4 wt % of water could still be saved by the sand soil containing 1.0 wt % superabsorbent composite. The results from this study show that the water absorbency of a superabsorbent composite is improved by the simultaneous introduction of O-MMT and SH into a PAA-AM network in comparison with the incorporation of only O-MMT or SH. Also, in comparison with PAA-AM/MMT/SH, an appropriate amount of O-MMT can benefit the developed composites with respect to their water absorbency, salt resistance, and capacity for water retention in sand soil. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Wenbo Wang;Yian Zheng;Aiqin Wang
Polymers for Advanced Technologies 2008 Volume 19( Issue 12) pp:1852-1859
Publication Date(Web):
DOI:10.1002/pat.1215
Abstract
Utilization of raw materials available in nature and their application to derive other useful products without any adverse impact on the environment has long been a desired goal. In this work, guar gum (GG) and attapulgite (APT) clay were used as raw materials for preparing guar gum-g-poly(acrylic acid)/attapulgite (GG-g-PAA/APT) superabsorbent composites through the graft copolymerization of GG, partially neutralized acrylic acid (AA) and APT in aqueous solution. The effects of reaction conditions such as concentrations of the initiator and crosslinker, APT content, etc. on water absorbency were investigated. The composite prepared under optimal conditions gave the best absorption of 529 g/g sample in distilled water and 61 g/g sample in 0.9 wt% NaCl solution. Swelling behaviors revealed that the superabsorbent composites retained a high water absorbency over a wide pH range of 4–11, and the developed composites also exhibited improved reswelling and water-retention capabilities. The superabsorbent composites can be utilized as eco-friendly water-manageable materials for agricultural and horticultural applications. Copyright © 2008 John Wiley & Sons, Ltd.
Co-reporter:Jianghua Liu;Aiqin Wang
Journal of Applied Polymer Science 2008 Volume 110( Issue 2) pp:678-686
Publication Date(Web):
DOI:10.1002/app.28717
Abstract
A novel chitosan-g-poly(acrylic acid)/organo-rectorite (CTS-g-PAA/OREC) nanocomposite superabsorbent was synthesized by aqueous polymerization using N, N′-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. Rectorite was organified with four different degree of hexadecyltrimethyl ammonium bromide, and the organification of rectorite was proved by FTIR and XRD. The effect of organification degree of rectorite on water absorbency of CTS-g-PAA/OREC with different organo-rectorite content was investigated. The swelling behaviors in distilled water and various pH solutions were also studied. The results from IR spectroscopy and XRD data show that acrylic acid had been grafted polymerization with chitosan and organo-rectorite and formed nanocomposite. Introducing organo-rectorite into the CTS-g-PAA polymeric network can improved water absorbency and swelling rate of CTS-g-PAA/OREC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Shuibo Hua;Aiqin Wang
Polymers for Advanced Technologies 2008 Volume 19( Issue 8) pp:1009-1014
Publication Date(Web):
DOI:10.1002/pat.1068
Abstract
Starch and sodium humate were utilized as raw material for synthesizing starch-g-poly(acrylic acid)/sodium humate (St-g-PAA/SH) superabsorbent by graft copolymerization reaction of starch (St) and acrylic acid (AA) in the presence of sodium humate (SH) in aqueous solution. The effect of weight ratio of AA to St, initial monomer concentration, neutralization degree of AA, amount of crosslinker, initiator and SH on water absorbency of the superabsorbent were studied. The swelling rate and swelling behavior in NaCl solution as well as reswelling ability of the superabsorbent were systematically investigated. The results showed that the superabsorbent synthesized under optimal conditions with SH content of 7.7 wt% and St content of 11.5 wt% exhibits water absorbency of 1100 g/g in distilled water and 86 g/g in 0.9 wt% NaCl solution, respectively. Introducing SH into the St-g-PAA polymeric network can improved the swelling rate and reswelling capability of the superabsorbent. Copyright © 2008 John Wiley & Sons, Ltd.
Co-reporter:Li Wang, Junping Zhang, Aiqin Wang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2008 Volume 322(1–3) pp:47-53
Publication Date(Web):5 June 2008
DOI:10.1016/j.colsurfa.2008.02.019
Batch adsorption experiments were carried out for the removal of methylene blue (MB) cationic dye from its aqueous solution using chitosan-g-poly(acrylic acid)/montmorillonite (CTS-g-PAA/MMT) nanocomposites as adsorbent. The factors influencing adsorption capacity of the nanocomposite such as initial pH value (pH0) of the dye solution, MMT content (wt%), weight ratio (wr) of AA to CTS and adsorption temperature (T) were investigated. The results showed that the wr of AA to CTS of the nanocomposites have great influence on adsorption capacities and introducing a small amount of MMT could improve adsorption ability of the CTS-g-PAA. The adsorption behaviors of the nanocomposite showed that the adsorption kinetics and isotherms were in good agreement with pseudo-second-order equation and the Langmuir equation, respectively, and the maximum adsorption capacity is 1859 mg/g for CTS-g-PAA/MMT with wt% of 30% and wr of 7.2:1. The desorption studies revealed that the nanocomposite provided the potential for regeneration and reuse after MB dye adsorption.
Co-reporter:Junping Zhang, Qin Wang, Li Wang, Aiqin Wang
Carbon 2007 Volume 45(Issue 9) pp:1917-1920
Publication Date(Web):August 2007
DOI:10.1016/j.carbon.2007.05.007
Co-reporter:Jianghua Liu, Qin Wang, Aiqin Wang
Carbohydrate Polymers 2007 Volume 70(Issue 2) pp:166-173
Publication Date(Web):20 September 2007
DOI:10.1016/j.carbpol.2007.03.015
A novel chitosan-g-poly(acrylic acid)/sodium humate (CTS-g-PAA/SH) multifunctional superabsorbent was prepared by graft polymerization among chitosan, acrylic acid and sodium humate in aqueous solution, using N,N′-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. And the samples were further characterized by means of FTIR, SEM and TGA. The effect of polymerization variables, including reaction temperature, content of initiator, crosslinker and sodium humate, the weight ratio of acrylic acid to chitosan, on water absorbency were studied. The swelling rate in distilled water and the swelling behavior in various pH value solutions were also investigated. The result from FTIR spectra showed that chitosan and sodium humate participated in graft polymerization reaction with acrylic acid. The introduced sodium humate could enhance water absorbency and the content of 10 wt% sodium humate gave the best absorption (183 g g−1 in distilled water and 41 g g−1 in 0.9 wt% NaCl solution).
Co-reporter:Junping Zhang, Qin Wang, Aiqin Wang
Carbohydrate Polymers 2007 Volume 68(Issue 2) pp:367-374
Publication Date(Web):21 March 2007
DOI:10.1016/j.carbpol.2006.11.018
A novel chitosan-g-poly(acrylic acid)/attapulgite superabsorbent composite with water absorbency of 159.6 g g−1 in distilled water and 42.3 g g−1 in 0.9 wt% NaCl solution was prepared by graft polymerization with chitosan, acrylic acid and attapulgite in aqueous solution, using N,N′-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. Factors influencing water absorbency of the superabsorbent composite were investigated, such as average molecular weight of chitosan, weight ratio of acrylic acid to chitosan, dewatering method, the amount of crosslinker and attapulgite. The result from FTIR spectra showed that –OH of attapulgite, –OH, –NHCO and –NH2 of chitosan participated in graft polymerization with acrylic acid. The introduced attapulgite enhanced thermal stability of the chitosan-g-poly(acrylic acid) superabsorbent and formed a loose and more porous surface. Introducing a small amount of attapulgite also enhanced water absorbency of the chitosan-g-poly(acrylic acid) superabsorbent.
Co-reporter:Hao Chen, Aiqin Wang
Journal of Colloid and Interface Science 2007 Volume 307(Issue 2) pp:309-316
Publication Date(Web):15 March 2007
DOI:10.1016/j.jcis.2006.10.054
The use of a natural palygorskite clay for the removal of Pb(II) from aqueous solutions for different contact times, pHs of suspension, and amounts and particle sizes of palygorskite clay were investigated. The variations of the pH value of Pb(II) solutions on natural palygorskite in the adsorption process were determined. Batch adsorption kinetic experiments revealed that the adsorption of Pb(II) onto palygorskite clay involved fast and slow processes. It was found that the adsorption mechanisms in the lead/palygorskite system follow pseudo-second-order kinetics with a significant contribution from film diffusion. SEM observations demonstrated that an important interaction at the lead–granule interface occurred during the adsorption process. The adsorption isotherms were described by means of the Langmuir and Freundlich isotherms and the Langmuir model represents the adsorption process better than the Freundlich model. The maximum adsorption capacity of Pb(II) onto natural palygorskite was 104.28 mg g−1.Pb(II) adsorption onto palygorskite clay occurs firstly at pores between particle aggregates, and then reaches complete equilibrium for some interactions such as palygorskite and water, complexation and ion-exchange during adsorption process.
Co-reporter:Yian Zheng, Ping Li, Junping Zhang, Aiqin Wang
European Polymer Journal 2007 Volume 43(Issue 5) pp:1691-1698
Publication Date(Web):May 2007
DOI:10.1016/j.eurpolymj.2007.02.023
A series of superabsorbent composites were synthesized by copolymerization reaction of partially neutralized acrylic acid on unexpanded vermiculite (UVMT) micropowder using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator in aqueous solution. And the samples were further characterized by means of fourier-transform spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The effects of vermiculite content on water absorbency were studied. Swelling behaviors of the superabsorbent composites in various cationic salt solutions (NaCl, CaCl2 and FeCl3), anionic salt solutions (NaCl, Na2SO4 and Na3PO4) and pH solutions were also systematically investigated. Results obtained showed that the equilibrium water absorbency increased with increasing UVMT content and the concentration of 20 wt.% clay gave the best absorption (1232 g/g in distilled water and 89 g/g in 0.9 wt.% NaCl). Data achieved also suggested that the water absorbency in various saline solutions decreased with an increase in the ionic strengths of these solutions. And it was found that at a higher ionic strength (>1 × 10−3 M), the water absorbency in monovalent cationic solutions was higher than those in multivalent cationic solutions. However, at the same ionic strength (>1 × 10−3 M), the effect of three anionic salt solutions on the swelling has the following order: NaCl < Na2SO4 < Na3PO4.
Co-reporter:Ping Li;Aiqin Wang;Junping Zhang
Macromolecular Materials and Engineering 2007 Volume 292(Issue 8) pp:962-969
Publication Date(Web):20 JUL 2007
DOI:10.1002/mame.200700081
A novel N-succinylchitosan-graft-polyacrylamide/attapulgite composite hydrogel was prepared by using N-succinylchitosan, acrylamide and attapulgite through inverse suspension polymerization. The result from FTIR spectra showed that OH of attapulgite, OH and NHCO of N-succinylchitosan participated in graft polymerization with acrylamide. The introduced attapulgite could enhance thermal stability of the hydrogel. Scanning electron microscopy observation indicates that the composite hydrogel has a microporous surface. The volume ratio of heptane to water, weight ratio of acrylamide to N-succinylchitosan and attapulgite content have great influence on swelling ability of the composite hydrogel. The composite hydrogel shows higher swelling rate and pH-sensitivity compared to that of without attapulgite.
Co-reporter:Ai-qin Wang;Li Wang;Li Wang;Ai-qin Wang
Journal of Chemical Technology and Biotechnology 2007 Volume 82(Issue 8) pp:711-720
Publication Date(Web):6 JUL 2007
DOI:10.1002/jctb.1713
To further improve the adsorption capacity of chitosan (CTS), a series of novel chitosan/organo-montmorillonite nanocomposites (CTS/OMMT) were synthesized and the adsorption abilities for Congo red (CR) investigated in this study. The nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the results indicated that an exfoliated nanostructure was formed in CTS/OMMT nanocomposites. Compared with the adsorption capacity of OMMT (192.4 mg g−1), CTS/OMMT with an amount of cetyltrimethylammonium bromide equal to 0.75 CEC of MMT and molar ratio of CTS to OMMT of 1:10 exhibited the higher adsorption capacity (290.8 mg g−1). The adsorption behaviours of OMMT and CTS/OMMT showed that the adsorption kinetics and isotherms were in good agreement with a pseudo-second-order equation and the Langmuir equation, respectively. The IR spectra revealed that a chemical interaction occurred between CTS/OMMT and CR. The adsorption capacity of CTS/OMMT nanocomposite was higher than that of other absorbents; this study suggested that the CTS/OMMT nanocomposite could be used as an adsorbent to remove CR dye from aqueous solution. Copyright © 2007 Society of Chemical Industry
Co-reporter:Wenji Wang, Hao Chen, Aiqin Wang
Separation and Purification Technology 2007 Volume 55(Issue 2) pp:157-164
Publication Date(Web):15 June 2007
DOI:10.1016/j.seppur.2006.11.015
A series of activated palygorskites were prepared by acid treatment and heat treatment, and the activated samples were applied as adsorbents for the removal of Cd(II) from aqueous solutions. The effects of various experimental parameters were investigated using a batch adsorption technique. Results showed that the adsorption capacity of the acid-treated palygorskite for Cd(II) increased with the increase of the concentration of initial Cd(II) solution, contact time and pH of initial suspension. It was found that the adsorption capacity of activated palygorskite increased with increasing the HCl concentration and calcination temperature, and the maximum adsorption capacity of acid-treated and heat-treated palygorskites for Cd(II) was obtained with 12 mol/L HCl and at about 300 °C. The adsorption isotherms of activated palygorskites for Cd(II) could be described by both Langmuir and Freundlich equations, and the Freundlich model is better to represent the adsorption process. The final pH values of the solution in all adsorption experiment were also measured. In addition, the interactions at the clay–water interface and the Cd(II) adsorption mechanisms onto the activated palygorskites were discussed.
Co-reporter:An Li;Junping Zhang;Aiqin Wang
Journal of Applied Polymer Science 2007 Volume 103(Issue 1) pp:37-45
Publication Date(Web):23 OCT 2006
DOI:10.1002/app.23901
A novel poly(acrylic acid)/attapulgite (APT)/sodium humate (SH) superabsorbent composite was synthesized through the graft copolymerization reaction of acrylic acid on APT micropowder and SH with N,N′-methylene bisacrylamide as a crosslinker and ammonium persulfate as an initiator in an aqueous solution. Various effects on the water absorbency, including the amounts of the crosslinker, initiator, APT, and SH, were investigated. The superabsorbent composite was characterized with Fourier transform infrared spectroscopy and scanning electron microscopy. The superabsorbent composite synthesized under optimal synthesis conditions with an APT concentration of 20% and an SH concentration of 20% exhibited absorption of 583 g of H2O/g of sample and 63 g of H2O/g of sample in distilled water and in a 0.9 wt % NaCl solution, respectively. The slow-release property of SH from the superabsorbent composite into water was measured, and a test of the water retention of the superabsorbent composite in soil was also carried out experimentally with and without the superabsorbent composite. The results showed that the superabsorbent composite had not only good water retention but also an additional slow-release property of SH. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 37–45, 2007
Co-reporter:Yaogang Zhao;Aiqin Wang;An Li
Journal of Applied Polymer Science 2007 Volume 105(Issue 6) pp:3476-3482
Publication Date(Web):30 MAY 2007
DOI:10.1002/app.26411
A series of poly(acrylic acid)/attapulgite superabsorbent composites were prepared by aqueous polymerization, using N, N′-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The effects of anion- and cation- exchanged attapulgite on water absorbency of superabsorbent composites were studied. The results showed that the anions and cations exchanged attapulgite can affect the physicochemical properties of attapulgite such as cation-exchange capacity and specific surface area, which in turn have influence on water absorbency of composites. Compared with that of monovalent cation-exchanged attapulgite, the water absorbencies of superabsorbent composites prepared with Ca2+, Al3+, and Fe3+-exchanged attapulgite are relative low. However, multivalent cations exchanged attapulgite would improve the reswelling capacities of the superabsorbent composites, which suggested that multivalent cations exchanged attapulgite could serve as an additional inorganic crosslinker in the polymeric network. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:Wenji Wang;Junping Zhang;Hao Chen;Aiqin Wang
Journal of Applied Polymer Science 2007 Volume 103(Issue 4) pp:2419-2424
Publication Date(Web):22 NOV 2006
DOI:10.1002/app.25452
A novel superabsorbent composite, polyacrylamide/attapulgite, from acrylamide (AM) and attapulgite (APT), was prepared by free-radical polymerization, using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator. The effects of hydrochloric acid (HCl) concentration, acidification time, and acidification temperature while acidifying APT and temperature and APT heat-activation on water absorbency of the superabsorbent composite in distilled water and in 0.9 wt % NaCl solution were studied. The water absorbency first decreases with increasing the HCl concentration while acidifying APT, and then increases with further increasing the HCl concentration. Prolongation of acidification time is of benefit to the increase of water absorbency. At a given HCl concentration, water absorbency for the composite increases with increasing acidification temperature. An important increase in water absorbency was observed after incorporating heat-activated APT into the polymeric network, reaching a maximum of 1964 g g−1 with the APT heat-activated at 400°C. Acid- and heat-activation can influence chemical composition, crystalline structure, cation exchange capacity (CEC), and specific surface area of APT according XRF, XRD, FTIR analysis, and physicochemical properties test, and then on water absorbency of corresponding PAM/APT superabsorbent composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2419–2424, 2007
Co-reporter:Wenji Wang;An Li;Junping Zhang;Aiqin Wang
Polymer Composites 2007 Volume 28(Issue 3) pp:397-404
Publication Date(Web):9 MAY 2007
DOI:10.1002/pc.20299
The effect of acid activation and thermal treatment of attapulgite on water absorbency of superabsorbent composite were investigated. Under the same preparation conditions, superabsorbent composite prepared with natural attapulgite exhibited a water absorbency of 639 g/g and it merely kept 71% of its initial water absorbency after 5 times of swelling–deswelling–reswelling test. However, superabsorbent composites prepared with 2–10 M hydrochloric acid acidified attapulgite and 100–400°C thermal treated attapulgite respectively exhibited the water absorbency of 884–1,241 g/g and 701–1,515 g/g. Also, those superabsorbent composites can keep 87% and 85% of their initial water absorbency after 5 times of swelling–deswelling–reswelling test, respectively. These results showed that, compared with superabsorbent composite prepared with natural attapulgite, the comprehensive water-absorbing properties of poly(acrylic acid)/ attapulgite superabsorbent composites were improved effectively by acid activation and thermal treatment of attapulgite. This improvement of water absorbencies and gel strength of superabsorbent composite may be due to synthetical factors such as changes in the crystalline structure and the specific surface area and improvement of the number and the activity of hydroxyl groups of attapulgite, which in turn influence the grafting efficiency of monomer, crosslinking density, and the structure of superabsorbent composite network. POLYM. COMPOS., 28:397–404, 2007. © 2007 Society of Plastics Engineers
Co-reporter:Junping Zhang;Hao Chen;Aiqin Wang
Polymer Composites 2007 Volume 28(Issue 2) pp:208-213
Publication Date(Web):2 MAR 2007
DOI:10.1002/pc.20384
A series of superabsorbent composite, polyacrylamide/attapulgite, from acrylamide (AM) and ion-exchanged attapulgite (APT) was prepared by aqueous polymerization, using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator. The effects of ion-exchanged APT on water absorbency of superabsorbent composites in distilled water and in 0.9 wt% NaCl solution were studied. The result indicates that higher cation-exchange capacity (CEC) and lower specific surface area (SSA) of APT treated with various anions are of benefit for improving water absorbency in distilled water. The effects of AlCl3 solution concentration and Al3+-exchanged APT content on water absorbency of the composite were also investigated. The concentration of AlCl3 solution has a great influence on water absorbency of the superabsorbent composite. Al3+-exchange of APT could also enhance reswelling ability of the corresponding composite, which indicates that Al3+-exchange of APT could improve gel strength and gives a direct evidence for its acting as an inorganic assistant crosslinker in the polymeric network. POLYM. COMPOS., 28:208–213, 2007. © 2007 Society of Plastics Engineers
Co-reporter:Junping Zhang;Yaogang Zhao;Aiqin Wang
Polymer Engineering & Science 2007 Volume 47(Issue 5) pp:619-624
Publication Date(Web):26 MAR 2007
DOI:10.1002/pen.20733
Al3+-attapulgite (Al3+-APT) was prepared by treating attapulgite (APT) with AlCl3 aqueous solution of various concentrations. The poly(acrylic acid)/Al3+-attapulgite (PAA/Al3+-APT) superabsorbent composite was prepared by reaction of partly neutralized acrylic acid, and Al3+-APT in aqueous solution using N, N′-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The surface morphology of the composite was investigated by SEM, and the Al3+-APT composite generated a relatively planar surface comparing the nature APT. The effects of Al3+-APT on hydrogel strength and swelling behaviors, such as equilibrium water absorbency, swelling rate, and reswelling capability, of the superabsorbent composites were also studied. The hydrogel strength and reswelling capability were improved, however, the equilibrium water absorbency and swelling rate decreased with increasing AlCl3 solution concentration. The equilibrium water absorbency firstly increased, and then decreased with increasing Al3+-APT content. The results indicate that Al3+-APT acts as an assistant crosslinker in the polymeric network, which has great influences on hydrogel strength and swelling behaviors of the PAA/Al3+-APT superabsorbent composites. POLYM. ENG. SCI., 47:619–624, 2007. © 2007 Society of Plastics Engineers.
Co-reporter:Junping Zhang, An Li, Aiqin Wang
Carbohydrate Polymers 2006 Volume 65(Issue 2) pp:150-158
Publication Date(Web):25 July 2006
DOI:10.1016/j.carbpol.2005.12.035
A novel starch phosphate-graft-acrylamide/attapulgite superabsorbent composite was prepared by graft-copolymerization among starch phosphate, acrylamide, and attapulgite in aqueous solution. In this paper, factors influencing water absorbency of the superabsorbent composite such as the molar ratio of NaOH to AM and the amount of starch phosphate and attapulgite were investigated. The superabsorbent composite acquired the highest equilibrium water absorbency of 1268 g g−1 when the molar ratio of COO−, COOH, and CONH2 is 10:3:11, the weight ratio of AM to starch phosphate is 5:1, and 10 wt% attapulgite was incorporated. The graft-copolymerization reaction mechanism, morphology, and thermal stability of the composites were also investigated by FTIR, scanning electron microscopy, and thermo-gravimetric analysis, respectively. The introduced starch phosphate and attapulgite endowed the composite a higher thermal stability. In addition, swelling rate, and equilibrium water absorbency in various saline solutions were investigated to study the effect of starch phosphate and attapulgite on swelling behaviors of the composite. The results indicate that the phosphorylation of starch and the introduction of attapulgite could greatly improve equilibrium water absorbency, swelling rate and salt-resistant properties of corresponding superabsorbent composite.
Co-reporter:Junping Zhang, Hao Chen, Aiqin Wang
European Polymer Journal 2006 Volume 42(Issue 1) pp:101-108
Publication Date(Web):January 2006
DOI:10.1016/j.eurpolymj.2005.06.029
A novel kind of superabsorbent composite, polyacrylamide/organo-attapulgite, from acrylamide (AM) and attapulgite (APT) was prepared by aqueous polymerization, using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator. APT was organified with five different degree of hexadecyltrimethyl ammonium bromide (HDTMABr), and the organification degree of APT was proved by FTIR, TGA and XRD. The effects of organification degree of APT on water absorbency and swelling rate of the superabsorbent composite in distilled water and in various saline solutions were investigated in this study. The effect of organification degree on reswelling ability of the superabsorbent composites was also investigated. The results indicate that the organification degree of APT had remarkable influence on swelling behaviors of the superabsorbent composites. The superabsorbent composite acquired its highest water absorbency when the organification degree of APT is 8.02 wt.%.
Co-reporter:Shengling Sun, Aiqin Wang
Separation and Purification Technology 2006 Volume 49(Issue 3) pp:197-204
Publication Date(Web):May 2006
DOI:10.1016/j.seppur.2005.09.013
Chitosan is an efficient metal chelater, but its practical use is limited due to the stability in acid solutions, adsorption capacities and selectivity. In the study, we attempt to find a more effective new adsorbent based on cross-linked chitosan derivative with Cu(II) as template, so a series of N,O-carboxymethyl-chitosan (CMC) with different degree of substitution (DS) were synthesized, and the influence factors on the adsorption capacities of CMC for Cu(II) ions measured in aqueous acetate, chloride and sulfate solutions were discussed, which indicate that the CMC show higher adsorption capacities in sulfate solution than in solutions of acetate or chloride. The cross-linked CMC with Cu(II) ions in sulfate solution as template (the template CMC resin)was prepared by cross-linked with glutaraldehyde. The adsorption selectivity of the template CMC resin in metal ions mixture solution was investigated. The result indicates that the template CMC resin can selectively adsorption the Cu(II) ions from the mixed solution containing three kinds of metal ions. It was also found that the template CMC resin has good reusability and adsorption capacities for Cu(II) ions after reuse for 10 times. The IR spectra and XPS data revealed that the sorption of CMC and the template CMC resin for Cu(II) ions are a chelate process between Cu(II) and the carboxyl, amino, and hydroxyl groups, but there is difference complexes structures between CMC and the template CMC resin.
Co-reporter:Jun Ping Zhang;Hao Chen;Ai Qin Wang
Polymers for Advanced Technologies 2006 Volume 17(Issue 5) pp:379-385
Publication Date(Web):12 JUN 2006
DOI:10.1002/pat.722
A novel multifunctional superabsorbent composite from acrylic acid (AA), acrylamide (AM), sodium humate (SH) and organo-attapulgite (organo-APT), PAA-AM/SH/organo-APT, was synthesized by aqueous solution polymerization, using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator. The organification of APT with hexadecyltrimethyl ammonium bromide (HDTMABr) was proved by FT-IR. The effects of organo-APT (HDTMA-APT) content in the superabsorbent composite and organification degree of it on water absorbency of the superabsorbent composite were studied. The effects of incorporated HDTMA-APT on swelling rate, water absorbency in various saline solutions and reswelling capability of the superabsorbent composite were also investigated. The results indicate that organification of APT had a remarkable influence on swelling behaviors of the superabsorbent composites. Comparing with the composite doped with APT, water absorbency for the composite incorporated with 10 wt% HDTMA-APT was enhanced from 996 to 1282 g g−1 in distilled water and from 63 to 68 g g−1 in 0.9 wt% NaCl solution, respectively. The superabsorbent composite acquired its highest water absorbency when the organification degree of APT was 8.02 wt%. Water absorbency of the composites in various saline solutions decreased with the increasing concentration, especially for the multivalent cations. In addition, swelling rate and reswelling capability of the superabsorbent composite were also improved by introducing HDTMA-APT into the composite compared with that of incorporating APT. Copyright © 2006 John Wiley & Sons, Ltd.
Co-reporter:Junping Zhang;Ruifeng Liu;An Li;Aiqin Wang
Polymers for Advanced Technologies 2006 Volume 17(Issue 1) pp:12-19
Publication Date(Web):5 JAN 2006
DOI:10.1002/pat.676
A series of superabsorbent composites, polyacrylamide/attapulgite (PAMA), were prepared from acrylamide (AM) and attapulgite micropowder in aqueous solution, using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator and then saponified with sodium hydroxide solution. This paper focuses on swelling behaviors of the PAMA superabsorbent composites in various saline solutions. The results indicate that saline solutions can weaken the swelling abilities of the PAMA compsites greatly. Water absorbency of the PAMA composites with 20 and 40 wt% attapulgite in aqueous chloride salt solutions has the following order: Li+ = Na+ = K+, Mg2+ > Ca2+ = Ba2+ all through the range of concentration investigated. However, swelling properties of the composites are complicated in CuCl2(aq), AlCl3(aq) and FeCl3(aq) solutions and are related to saline solutions concentration. The deswelling behavior of PAMA composites is more obvious in univalent chloride salt solutions than in divalent and trivalent ones. The influence of kind and valence of anions on swelling ability of the composites is limited and almost the same. Moreover, reswelling capability, practical water retention ability in sand soil of the composites and the effect of pH on water absorbency of the PAMA composites were investigated. The PAMA composite shows good water retention and reswelling ability in sand soil, and may be used as a recyclable water-managing material for the renewal of arid and desert environment. Copyright © 2006 John Wiley & Sons, Ltd.
Co-reporter:Junping Zhang;An Li;Aiqin Wang
Polymer Engineering & Science 2006 Volume 46(Issue 12) pp:1762-1767
Publication Date(Web):8 NOV 2006
DOI:10.1002/pen.20630
A novel superabsorbent composite from acrylamide (AM) and attapulgite (APT), polyacrylamide/attapulgite (PAM/APT), was prepared by polymerizing AM with the existence of APT in aqueous solution, and then saponified with NaOH solution. Considering the impacts of hydrophilic groups (COONa, COOH, and CONH2) on properties of the PAM/APT composite, the effects of saponification mode, molar ratio of NaOH to AM and saponification time on water absorbency, hydrophilic group content, and surface morphology were investigated systematically. The results indicate that the two-step adding NaOH mode is superior to that of the one-step mode. Among the superabsorbent composite incorporated with 30 wt% APT, the composite saponified at 95°C for 2 h with the molar ratio of 0.6 for NaOH to AM acquired the highest water absorbencies of 1715g g−1 and 87.8g g−1 in distilled water and in 0.9 wt% NaCl solution, respectively. The molar ratio of various hydrophilic groups at this time was 10:3:11 for COONa, COOH, and CONH2 determined using linear potentiometric titration method. POLYM. ENG. SCI. 46:1762–1767, 2006. © 2006 Society of Plastics Engineers.
Co-reporter:Junping Zhang, Hao Chen, Aiqin Wang
European Polymer Journal 2005 Volume 41(Issue 10) pp:2434-2442
Publication Date(Web):October 2005
DOI:10.1016/j.eurpolymj.2005.03.022
A novel kind of salt-resistant superabsorbent composite, polyacrylamide/attapulgite, from acrylamide (AM) and attapulgite (APT) was prepared by free-radical aqueous polymerization, using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator. The organification of APT with hexadecyltrimethyl ammonium bromide (HDTMABr) was proved by FTIR and XRD. The effects of acidified APT (H+-APT), organo-APT (HDTMABr-APT) and the content of APT in the superabsorbent composite on the water absorbency and the initial swelling rate for the superabsorbent composite in distilled water and in various saline solutions were studied. The effects of incorporated HDTMABr-APT and H+-APT on the reswelling ability of the superabsorbent composites were investigated. The results indicate that the incorporation of APT had remarkable influence on the improvement of water absorbency and swelling rate of the composites. Comparing with the composite doped with H+-APT, the water absorbency for the composite doped with 10 wt% HDTMABr-APT was enhanced from 2140 g g−1 to 2800 g g−1 in distilled water and from 100 g g−1 to 121 g g−1 in 0.9 wt% NaCl solution, respectively. The water absorbency of the composites in various saline solutions decreased with the increasing concentration, especially for the multivalent cations. In addition, the reswelling ability of the superabsorbent composites is also improved evidently by adding a small amount of HDTMABr-APT into the composite, comparing with that of incorporated with H+-APT.
Co-reporter:Junping Zhang;An Li;Aiqin Wang
Polymers for Advanced Technologies 2005 Volume 16(Issue 9) pp:675-680
Publication Date(Web):8 AUG 2005
DOI:10.1002/pat.641
A novel poly(acrylic acid)/sodium humate superabsorbent composite was synthesized by aqueous solution polymerization of acrylic acid using N, N′-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator in the presence of sodium humate. The effects on water absorbency such as initial monomer concentration, degree of neutralization of acrylic acid, amount of crosslinker, initiator and sodium humate, etc. were investigated. The water absorbency of the superabsorbent composite synthesized under optimal synthesis conditions with a sodium humate content of 20% exhibited an absorption of 1268 g H2O/g sample and 93 g H2O/g sample in distilled water and in 0.9 wt% NaCl solution, respectively. Swelling rate and water retention tests were also carried out. The results show that sodium humate, as a kind of functional filler, can enhance comprehensive properties of superabsorbent composite and reduce the product cost significantly. Copyright © 2005 John Wiley & Sons, Ltd.
Co-reporter:An Li;Ai Qin Wang
Polymers for Advanced Technologies 2005 Volume 16(Issue 11‐12) pp:813-820
Publication Date(Web):14 NOV 2005
DOI:10.1002/pat.657
A novel multifunctional superabsorbent composite from acrylic acid (AA), acrylamide (AM), sodium humate (SH) and attapulgite (APT), PAA-AM/SH/APT, was synthesized by aqueous solution polymerization, using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator. In this paper, not only the effects of the ratio of AA to AM, SH and APT content on the saturated water absorbency, but also various swelling behaviors of the composite were systematically investigated. The results show that comprehensive performances of the superabsorbent are improved by introducing functional components into a poly(acrylic acid-acrylamide) (PAA-AM) network. Functionality of the composite in practice was also investigated by studying the release of SH and by growing Elymus dahuricus Turcz (a kind of grass) plants in soil with and without using the superabsorbent composite. The roots and stems of Elymus dahuricus Turcz were found to be sturdier compared with the plants grown without the superabsorbent composite. Copyright © 2005 John Wiley & Sons, Ltd.
Co-reporter:Wenbo Wang, Junping Zhang, Aiqin Wang
Applied Clay Science (September 2009) Volume 46(Issue 1) pp:21-26
Publication Date(Web):September 2009
DOI:10.1016/j.clay.2009.07.001
Co-reporter:Bin Mu, Aiqin Wang
Journal of Environmental Chemical Engineering (March 2016) Volume 4(Issue 1) pp:1274-1294
Publication Date(Web):1 March 2016
DOI:10.1016/j.jece.2016.01.036
•Various modification strategies of PAL for dye adsorption are reviewed.•To disaggregate PAL crystal bundles is indispensible to improve its absorption properties.•PAL and its composite as the adsorbent for dye removal are discussed.•Future perspectives in this direction are proposed.With the continuous increase in the demand of dyes, the dye wastewater is becoming a major environmental threat. Adsorption techniques are widely used to remove dyes from wastewater using clay minerals, especially a naturally available one-dimensional palygorskite due to high surface area, moderate cation exchange capacity, excellent salt resistance compared with other clay minerals. Although the maximum adsorption of natural palygorskite toward dyes far exceeded the cation exchange capacity of palygorskite, it is difficult to completely release the adsorption capacity of palygorskite toward dyes due to the existence of the bulk crystal bundles or aggregates originated from the interparticle Van der Waals’ and hydrogen bonding interactions. Therefore, it is indispensible to disaggregate palygorskite crystal bundles and introduce functional groups to improve the microscopic structure of palygorskite and increase the adsorption sites via various physical and chemical modifications. This review article summarizes the development on the modified palygorskite with different physical or chemical methods and palygorskite-based composite used as adsorbents for the adsorption of dyes from aqueous solution by reviewing a comprehensive literature combined with our group’s research achievements. In addition, few conclusions and suggestions have been proposed for future research.Download high-res image (206KB)Download full-size image
Co-reporter:Junping Zhang, Aiqin Wang
Reactive and Functional Polymers (August 2007) Volume 67(Issue 8) pp:737-745
Publication Date(Web):August 2007
DOI:10.1016/j.reactfunctpolym.2007.05.001
Co-reporter:Yian Zheng, Junping Zhang, Aiqin Wang
Chemical Engineering Journal (1 December 2009) Volume 155(Issues 1–2) pp:215-222
Publication Date(Web):1 December 2009
DOI:10.1016/j.cej.2009.07.038
In this work, a novel composite adsorbent with three-dimensional cross-linked polymeric networks based on chitosan (CTS) and attapulgite (APT) was prepared via in situ copolymerization in aqueous solution, and its efficacy for removing ammonium nitrogen (NH4+-N) from synthetic wastewater was investigated using batch adsorption experiments. In the adsorption test, the pH effect, adsorption kinetics, isotherms, and desorbability were examined. A comparison between as-prepared adsorbent and clay, powdered activated carbon (PAC), and other reported adsorbents was also carried out. The results indicate that as-prepared composite adsorbent is pH-dependent and has faster adsorption kinetics and higher adsorption capacity. At natural pH, the composite adsorbent with 20 wt.% APT can adsorb 21.0 mg NH4+-N per gram, far higher than the other adsorbents involved. The adsorbed NH4+-N can be completely desorbed by 0.1 mol/L NaOH within 10 min. All information obtained give an indication that the composite can be used as a novel type, fast-responsive and high-capacity sorbent material for NH4+-N removal.
