Application of Crosslinked Acrylamidoxime/2-Acrylamido-2-methylpropane Sulfonic Acid Copolymer in Wastewater Treatment

Crosslinked acrylonitrile/acrylamidoxime/2-acrylamido-2-methylpropane sulfonic acid (AN/AAx/AMPS) based hydrogels was prepared by radical solution polymerization technique. The structures of hydrogels were characterized by FTIR analysis and the results were consistent with the expected structures. These hydrogels were used for the separation of Cd(II), Cu(II), and Fe(III) ions from their aqueous solutions. The influence of the uptake conditions such as pH, time, and initial feed concentration on the metal ion binding capacity of hydrogel was also tested. The selectivity of the hydrogel toward the different metal ions tested was Cd(II)>Fe(III)>Cu(II). The recovery of metal ions was also investigated in acid media.     

Removal of Pb2+ and Cd2+ ions from aqueous solutions using guanidine modified hydrogels

In this study, experimental measurements have been made on the batch adsorption of cadmium and lead ions from aqueous solutions using poly(guanidine modified 2‐acrylamido‐2‐methylpropan sulfonic acid/acrylic acid/N‐vinylpyrrolidone/2‐Hydroxyethyl methacrylate), P(AMPSG/AAc/NVP/HEMA) hydrogels. The guanidyl end group bearing AMPSG monomer was synthesized from the reaction of AMPS and guanidine. The hydrogels were prepared by UV‐curing technique. The morphology of the dry H10‐hydrogel sample was examined by SEM. The influence of the uptake conditions, such as pH, functional monomer per cent, contact time, initial feed concentration, and foreign metal ions on the metal ion binding capacity of hydrogel, was also tested. The selectivity of the hydrogel toward the different metal ions tested was Hg(II) > Pb(II) > Au(III) > Cd(II). The adsorption isotherm models were applied to the experimental data, and it was seen that the Langmuir isotherm model was the best fit for the adsorption of Cd(II) and Pb(II) ions on P(AMPSG/AAc/NVP/HEMA) hydrogel. It was found that adsorbed lead and cadmium ions on P(AMPSG/AAc/NVP/HEMA) hydrogel can be effectively desorbed by acid leaching and the regenerated P(AMPSG/AAc/NVP/HEMA) hydrogel can be reused almost five times less without any loss of adsorption capacity. Copyright © 2009 John Wiley & Sons, Ltd.     

Enhanced swelling and adsorption properties of AAm‐AMPSNa/clay hydrogel nanocomposites for heavy metal ion removal

Novel type hydrogel‐clay nanocomposites based on the acrylamide (AAm)‐ 2‐acrylamido‐ 2‐methylpropane sulfonic acid (AMPS) sodium salt and clay were synthesized via in situ copolymerization in aqueous solution. Samples were characterized by determining total basic group (TGB) content and swelling degree, XRD analysis, and FTIR spectroscopy. Effects of monomer ratio and clay amount on the swelling properties of the samples were investigated. It was found that the hydrogel/clay nanocomposites exhibited improved swelling capacity compared with the hydrogels. Samples were used to remove heavy metal ions (Cu (II), Cd (II), and Pb (II)) from aqueous solution in competitive and non‐competitive conditions for the first time. The effects of time and pH of the initial metal ion solution on the adsorption capacity were investigated and selectivity properties of the samples were evaluated. It was found that incorporation of a low amount of clay (10% (wt)) into the polymer structure increased the heavy metal ion adsorption capacity of the sample. It was concluded that the AAm‐AMPS/clay nanocomposites could be used as novel type, fast‐responsive, and high capacity sorbent materials in heavy metal removing processes. Copyright © 2007 John Wiley & Sons, Ltd.     

Preparation and characterization of poly(2-acrylamido-2-methylpropane-sulfonic acid)/Chitosan hydrogel using gamma irradiation and its application in wastewater treatment

Radiation grafting of chitosan with 2-acrylamido-2-methyl propane sulfonic acid (AMPS) has been successfully performed. The effect of absorbed dose (kGy) and the chitosan:AMPS ratio on graft hydrogelization was studied. The structure of the prepared hydrogel was confirmed using infrared spectroscopy (IR). Thermal properties were simultaneously studied by thermogravimetric analysis (TGA). The effect of the polymerization variables on the swelling % of the prepared hydrogel was investigated. The highest equilibrium degree of swelling (38.6 g/g) and gel % (94.7%) of the prepared chitosan–AMPS hydrogel was at 40% AMPS and absorbed dose of 10 kGy. The removal of methylene blue, acid red dye, Cd (II) and Cr (III) from composed wastewater was also investigated. The effect of pH, the chitosan:AMPS ratio and the concentration of the pollutant on the adsorption process were studied.     

高强度PAMPS-PAAm互穿网络凝胶及其溶胀性能

通过考察不同单体浓度或离子强度下凝胶的力学性能和溶胀特性,对聚2-丙烯酰胺-2-甲基丙磺酸(PAMPS)与聚丙烯酰胺(PAAm)形成的互穿网络凝胶的高强度性能和作用机理进行了研究.结果表明:PAMPS-PAAm互穿网络凝胶的力学强度对c(AMPS)存在一个最佳值(1 mol/L),且随c(AAM)的增大而显著增大(0.5～4 mol/L).当c(AMPS)=1 mol/L、c(AAM)＝4 mol/L时,互穿网络凝胶的最大抗压强度达6.46 MPa;改变凝胶体系内水的离子强度,PAMPS-PAAm凝胶在0.25 mol/kg离子强度时的抗压强度与纯水状态下相比增加了29%.     

Synthesis of cross-linked carboxymethyl cellulose and poly (2-acrylamido-2-methylpropane sulfonic acid) hydrogel for sustained drug release optimized by Box-Behnken Design

This research aims to fabricate and characterize chemically crosslinked CMC/PVP-co-poly (AMPS) based hydrogel for the sustained release of model drug metoprolol tartrate through the free radical polymerization technique. Box-Behnken Design was used to optimize CMC/PVP-co-poly (AMPS) hydrogel by varying the content of reactants such as; polymers (CMC and PVP), monomer (AMPS), and crosslinker (EGDMA). Carboxymethyl cellulose (CMC) was crosslinked chemically with AMPS with a constant ratio of PVP by the ethylene glycol dimethacrylate as the crosslinker in the presence of sodium hydrogen sulfite (SHS)/ammonium peroxodisulfate (APS) as initiators. After developing CMC-based hydrogels using different polymers, monomer, and crosslinker concentrations, this study encompassed dynamic swelling, sol–gel fraction, drug release and chemical characterizations such as FTIR, XRD, TGA, DSC, and SEM. In vitro drug release and swelling were performed at 1.2 and 6.8 pH to determine the sustained release pattern and pH-responsive behavior. These parameters depended on the crosslinker, polymer, and monomer ratios used in the formulation development. XRD, SEM, and FTIR showed the successful grafting of constituents resulting in the formation of a stable hydrogel. DSC and TGA confirmed the thermodynamic stability of the hydrogel. Hydrogel swelling was increased with an increase in the ratio of monomer; however, an increase in the ratio of polymer and crosslinker decreased the hydrogel swelling. In vitro gel fraction and drug release also depended on polymer, monomer, and crosslinker ratios. The fabricated CMC/PVP-co-poly (AMPS) hydrogels constituted a potential system for sustained drug delivery.     

Synthesis and Characterization of Hydrogel Nanoparticles Through Inverse Microemulsion Polymerization of 2-Acrylamido-2-methyl-1-propanesulfonic Acid

Nanosized hydrogel particles prepared through inverse microemulsion polymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid, using the combination of an oil soluble emulsifier (SPAN80) with a water soluble emulsifier (TWEEN 80), and precise determination of HLB range related to the formation of stable single phase microemulsions.

The effect of crosslink density, water phase to oil phase ratio, and the hydrophilic-lipophilic balance (HLB) value on polymerization rate, particle size, and swelling ratio were investigated. It found that polymerization rate and particle size are strongly dependent on the water phase to oil phase ratio. Hydrogel samples prepared using oil soluble and water soluble initiators and the results showed that the initiator type had a great influence on monomer conversion and particle size. Effect of pH on equilibrium swelling of hydrogels was studied by dynamic light scattering and hydrogels showed pH-independent swelling behavior in a broad range of pH values. We also reported and discussed the crosslink density distribution in nanogels prepared by inverse microemulsion polymerization.     

Structurally Enhanced Hydrogel Nanocomposites with Improved Swelling and Mechanical Properties

In this work, structurally enhanced hydrogel nanocomposites based on 2-acrylamido-2 methyl propane sulfonic acid (AMPS)-acrylamide (AAM) copolymer with high hydrophilic group content were prepared by in-situ copolymerization by using different types of clay (montmorillonite, mica and halloysite). Nanocomposite hydrogels were characterized by Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) analyses and determination of swelling degrees of the samples. Mechanical properties of the samples were also investigated by determination of the compressive elastic modulus. It was also found that exfoliated or highly expanded intercalated nanocomposite structure was obtained and clay incorporation into the AMPS-AAM hydrogel structure improved its swelling capacity. The highest swelling capacity (1030 g H₂O/g) was observed for the nanocomposite sample prepared with the montmorillonite amount of 5% (w). Furthermore, mechanical strength of the hydrogels against compression forces was significantly improved by the clay addition. It was found that the type of clay, in other word filler geometry, affected the compressive elastic modulus (E) of the samples. It was concluded that halloysite, which is considered to be a one dimensional (1D) nanotubular filler was less effective to enhance the compressive elastic modulus (E) of such materials compared with the montmorillonite and mica having two dimensional (2D) platelet or disk-like shapes at a particular amount of clay.     

Morphogenetic control of calcite crystal growth in sulfonic acid based hydrogels

In this paper the mineralization of CaCO(3) in various hydrogel matrices is presented. Sulfonic acid based hydrogels were prepared by introduction of sulfonate-containing monomers into a polyacrylamide network. The sulfonate content of polyacrylamide-co-vinylsulfonate and polyacrylamide-co-allylsulfonate decreases during elution of the copolymers in demineralized water, indicating insufficient linking of the sulfonate-bearing monomers within the hydrogel. In contrast to this, acrylamidomethylpropanesulfonate (AMPS) effectively copolymerizes with acrylamide (AAm) monomers. To study the influence of spatial arrangement of ionic functional groups within hydrogel networks on the mineralization of CaCO(3), AMPS copolymers with different degrees of AMPS cross-linking were synthesized. For the mineralization experiments the copolymers were placed into a double-diffusion arrangement. Calcite as the thermodynamically stable modification of CaCO(3) was obtained with a particular morphology. The pseudocubic habitus resembles aggregates obtained by mineralization in pure polyacrylamide. However, closer examination of the aggregates by scanning electron microscopy (SEM) shows that the crystal growth in the AMPS copolymers is different from that observed in polyacrylamide. Whereas the morphology of the calcite aggregates could be fine-tuned by using copolymers with different sulfonate content, the spatial distribution of the ionic functional groups alters the course of crystallization. Calcium ions are locally accumulated due to the heterogeneous distribution of functional sulfonate groups within the copolymer network. Thereby the nucleation of calcite is triggered, resulting in enhanced mineralization.     

Adsorption of Dyes Using Multi-walled Carbon Nanotube Hydrogel

The hydrophilic multi-walled carbon nanotube(MWCNT)hydrogel was prepared using acrylic acid,acrylamide and hydrophilic MWCNT.The orthogonal experiment was applied to optimize the synthetic conditions.The MWCNT hydrogel was characterized by Fourier transform infrared spectrophotometer(FTIR)and scanning electron microscopy(SEM)analysis.The MWCNT hydrogel was used as the adsorbent to adsorb water-soluble cationic dye.This study evaluated the adsorption performance of hydrogels on four dyes of safranine Ts crystal violet,malachite green and methylene blue in water.The effects of the amount of hydrogel,the size of hydrogel,pH;and the temperature on the adsorption performance were investigated.The adsorption kinetic and adsorption isotherm curves were measured.The experimental results show that the MWCNT hydrogel can be easily separated from water and the adsorption capacity is much greater compared to the hydrogel without MWCNT.The MWCNT hydrogels can be used in wastewater treatment with a great potential.     

Embedding magnetic nanoparticles into polysaccharide-based hydrogels for magnetically assisted bioseparation.

Based on the preparation of biocompatible polysaccharide-based hydrogels with stimuli-responsive properties by the copolymerization of maleilated carboxymethyl chitosan with N-isopropylacrylamide, novel magnetic hybrid hydrogels were fabricated by the in situ embedding of magnetic iron oxide nanoparticles into the porous hydrogel networks. Scanning electron microscopy (SEM) and thermogravimetric (TG) analyses showed that the size, morphology, and content of the iron oxide nanoparticles formed could be modulated by controlling the amount of maleilated carboxymethyl chitosan. As confirmed by X-ray diffractometry (XRD), equilibrium swelling ratio, and differential scanning calorimetry (DSC) measurements, the embedding process did not induce a phase change of the magnetic iron oxide nanoparticles, and the resultant hybrid hydrogels could retain the pH- and temperature-responsive characteristics of their hydrogel precursors. By investigating the partition coefficients of bovine serum albumin as a model protein, this magnetic hydrogel material was found to hold a potential application in magnetically assisted bioseparation.     

快速响应的温敏性聚(N-异丙基丙烯酰胺)水凝胶的合成及表征

快速响应的温敏性聚(N-异丙基丙烯酰胺)水凝胶的合成及表征;N-异丙基丙烯酰胺;水凝胶;温敏性;快速响应     

聚N-异丙基丙烯酰胺/纳米SiO_2复合水凝胶的合成及溶胀性能

通过纳米SiO2的表面功能化,在其表面引入乙烯基功能基团,在H2OTHF的混合溶剂中,超声分散后,交联剂N,N′亚甲基双丙烯酰胺存在时,于25℃下使其与N异丙基丙烯酰胺共聚,制得聚N异丙基丙烯酰胺纳米SiO2复合水凝胶,并用FTIR和SEM对产物进行了表征.研究了凝胶的溶胀动力学,消溶胀动力学和温度敏感性.实验结果表明,纳米SiO2的引入,改善了聚N异丙基丙烯酰胺水凝胶在低温时的溶胀性能和在高温时对水的释放性能,并讨论了引起这些性能改变的原因.     

ABSORPTION OF METAL IONS AND SWELLING PROPERTIES OF POLY(ACRYLIC ACID-CO-ITACONIC ACID) HYDROGELS

Hydrogels of acrylic acid and itaconic acid has been synthesized with different monomers ratios. The swelling process of the different xerogels immersed in water and salt solutions has been studied. The swelling of hydrogels loaded with metal cations (Cu²⁺, Zn²⁺) was also investigated. The swelling process was monitored by the increase in the weight of hydrogel as a function of time. The absorption properties of metal ions were studied by using the hydrogel, and different concentrations of copper and zinc solutions (prepared from sulphate salts). The influence of pH on the absorption process was studied. For the absorption of metal ions, the amount of ions absorbed within the hydrogel can be calculated from the initial and equilibrium concentrations of the metal ions in aqueous phase, the weight of the hydrogel, and the volume of solution used. Metal absorption increased when pH, salt concentration in external solution and itaconic acid content is levelled.

The swelling isotherms which consisted of an initial fast increase levelled off asymptotically to the equilibrium swelling limit. The experimental data clearly suggest that our hydrogels follow a second-order kinetics for both cases (unload and metal loaded). The kinetics rate constant and the equilibrium water content, K, have been calculated for every monomer ratio from the experimental data according to the kinetics equation. Both magnitudes decreased as the itaconic acid content decreases in the xerogels.     

新型半纤维素基磁性水凝胶的制备及性能

采用H₂O₂-Vc氧化还原体系引发半纤维素衍生物,以表面修饰的Fe₃O₄粒子作为磁性组分,利用接枝共聚方法制备了新型半纤维素基磁性水凝胶. 分别用傅里叶变换红外(FTIR)光谱、X射线光电子能谱(XPS)和扫描电子显微镜(SEM)对水凝胶的结构及形貌进行了表征,利用X射线衍射(XRD)和振动样品磁强计(VSM)对水凝胶的晶型结构及磁性能进行了分析,发现Fe₃O₄粒子均匀分散在凝胶网络中,半纤维素基磁性水凝胶表现出良好的顺磁性. 考察了丙烯酸/半纤维素比例、Fe₃O₄粒子含量及交联剂用量对水凝胶溶胀性能的影响,并探讨了该水凝胶的溶胀机理,它在pH 8 缓冲溶液中的溶胀较好符合Fickian 和Schott 动力学模型. 通过SEM和溶胀性能分析表明,随着pH值的升高水凝胶的孔径增大,水凝胶的溶胀率逐渐增大. 制备的水凝胶被用于溶菌酶吸附研究,结果表明磁性凝胶的吸附量大于非磁性水凝胶,水凝胶的吸附行为符合Freundlich 和Temkin 等温模型.     

Thermoresponsive properties of porous poly(N‐isopropylacrylamide) hydrogels prepared in the presence of nanosized silica particles and subsequent acid treatment

Porous poly(N‐isopropylacrylamide) hydrogels were prepared by the free‐radical polymerization of its monomer and a suitable crosslinker in the presence of spherical silica particles of different sizes (74 and 1600 nm) and by the subsequent acid extraction of silica. The yields were 81–83%, and the yields were not affected by the silica content. Scanning electron microscopy observations revealed the porous structure of the hydrogels. Porous and nonporous hydrogels showed volume phase transitions from swelling states to deswelling states at approximately 30 °C, as analyzed by the ratio of the diameter of cylinder‐shaped hydrogels to that of the glass tube used for the hydrogel preparation at the corresponding temperature. Deswelling, which was analyzed by rapid changes in the temperature of the aqueous media from 20 to 40 °C, was facilitated by decreased silica particle size and increased silica content. The deswelling rate constant of the hydrogel prepared with 74‐nm silica at 10 v/v % (silica/solvent) was more than 1500 times greater than that of conventional hydrogels. Swelling was similarly analyzed through changes in the temperature from 40 to 20 °C and was independent of the pore structure. The deswelling–swelling cycle was repeatable with reasonable reproducibility. Moreover, the mechanical strength of the porous hydrogels was significantly maintained compared with that of conventional nonporous hydrogels. This method produced thermoresponsive hydrogels of suitable mechanical strength and remarkable deswelling properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4228–4235, 2002     

Macroporous Poly(Acrylamide) Hydrogels: Swelling and Shrinking Behaviors

Macroporous poly(acrylamide) hydrogels have been synthesized by using poly(ethylene glycol) (PEG) with three different molecular weights as the pore‐forming agent. Scanning electron microscope graphs reveal that the macroporous network structure of the hydrogels can be adjusted by applying different molecular weights of PEG during the polymerization reaction. The swelling ratios of the PEG‐modified hydrogels were much higher than those for the same type of hydrogel prepared via conventional method. However, the swelling/deswelling ratios of the PEG‐modified hydrogels were affected slightly by the change in the amount of the PEG. Scanning electron microscopy experiments, together with swelling ratio studies, reveal that the PEG‐modified hydrogels are characterized by an open structure with more pores and higher swelling ratio, but lower mechanical strength, compared the conventional hydrogel. PAAm has potential applications in controlled release of macromolecular active agents.     

PAMPS/SiO_2杂化水凝胶的合成及电场敏感性研究

以2-丙烯酰胺-2-甲基丙磺酸(AMPS)为有机原料,正硅酸乙酯(TEOS)为无机原料,过硫酸钾为引发剂,N,N'-亚甲基双丙烯酰胺为交联剂,通过原位-凝胶水溶液聚合法合成了一系列不同二氧化硅含量和不同聚离子浓度的聚(2-丙烯酰胺-2-甲基丙磺酸)/二氧化硅杂化电场敏感性水凝胶.通过扫描电子显微镜(SEM)表征凝胶的结构,研究水凝胶在去离子水以及氯化钠溶液中的溶胀和消溶胀行为.结果表明,系列凝胶的平衡溶胀度介于224.9至325.6之间,复合凝胶的溶胀速率随TEOS用量的增加而降低;除理想杂化凝胶外,随着聚离子浓度的升高,凝胶在氯化钠溶液中的消溶胀速率逐渐减小.对凝胶的电场敏感性研究表明,当聚离子浓度大于氯化钠溶液浓度时,凝胶进一步溶胀,反之则消溶胀,其中杂化凝胶的再溶胀性能减弱,而消溶胀行为变得更为明显.同时制得的理想杂化凝胶,较纯有机凝胶具有更为理想的力学性能,最大抗压缩强度可达23.4 MPa.     

Studies on radiation synthesis of polyethyleneimine/acrylamide hydrogels

Polyethyleneimine(PEI)/acrylamide(AAM) hydrogels were synthesized by γ-radiation-induced polymerization/crosslinking of aqueous mixtures containing different ratios of PEI and AAM. The gel percentage and equilibrium degree of swelling (EDS) of the synthesized hydrogels were investigated. The compositions of the hydrogels produced were found to be different from the feed composition. Ion-chromatography technique was used to determine the amount of Pb (II) and Cd (II) absorbed by the hydrogel. The maximum binding capacity of the PEI/AAM hydrogels, for Pb and Cd was found to be 19 and 12.6 mg/g, respectively, (at 100 ppm). PEI/AAM hydrogels had better metal uptake efficiency than the pure AAM hydrogel at concentrations less than 50 ppm. Pure PEI was observed to be highly degrading type polymer on exposure to gamma radiation. TGA and FT-IR techniques were used to characterize the prepared hydrogels.     

Characterization and Evaluation of Acrylic Acid Co-2-acrylamido-2-methylpropane-1-sulfonic Acid Hydrogels for Uranium Recovery

Crosslinked 2-acrylamido-2-methyl-1-propane sulfonic acid -co- acrylic acid (AMPS/AA) hydrogels were synthesized by radical polymerization in the presence of N,N′-methylenebisacrylamide (MBA) as the crosslinking agent using potassium persulfate (KPS) as initiator. Hydrogels with different compositions and crosslinker concentrations were prepared. The structures of hydrogels were characterized by FTIR analysis. Thermal stabilities of the hydrogels were investigated using TGA and DSC analysis. Swelling kinetics and the equilibrium water content (EWC) of the hydrogels were studied. The swelling behavior of these hydrogels was investigated at different pHs at room temperature. Also the swelling behavior of these hydrogels was investigated at different ionic strength. The ability of the prepared hydrogels to bind uranium(VI) was tested under noncompetitive conditions by batch equilibrium procedure. Experimental work using uranyl nitrate hexahydrate bought from the local market was carried out in the safeguards destructive analysis laboratory (KMP-I) in the National Center for Nuclear Safety and Radiation Control.