VMT/P(AMPS-co-AA)复合高吸水树脂及其对染料吸附性能

研究了溶液p H、盐浓度对辉光放电电解等离子体引发合成的蛭石/聚(2-丙烯酰胺-2-甲基丙磺酸-co-丙烯酸)〔VMT/P(AMPS-co-AA)〕复合高吸水树脂的溶胀行为的影响,考察了染料p H、吸附时间、染料浓度等对树脂吸附量的影响,同时对树脂的吸附-解吸重复利用性能进行了测试。结果表明,VMT/P(AMPS-co-AA)具有高吸水性、p H敏感性、盐敏感性以及高吸附性。该树脂在蒸馏水中的最大溶胀率达到822.4 g/g,对阳离子染料亚甲基蓝(MB)、结晶紫(CV)和孔雀石绿(MG)的吸附量分别可达2 027.8、2 171.8和883.2 mg/g。在p H=6.5和25℃下,其对染料的吸附行为符合动力学准二级模型,该树脂还具有一定的吸附-解吸性能和重复利用性能。     

辉光放电电解等离子体法制备VMT/P(AMPS-co-AA)复合高吸水树脂

在水溶液中,以蛭石(VMT)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)和丙烯酸(AA)为原料,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,用辉光放电电解等离子体(GDEP)引发制备蛭石/聚(2-丙烯酰胺-2-甲基丙磺酸-co-丙烯酸)[VMT/P(AMPS-co-AA)]复合高吸水树脂。考察了放电电压、放电时间、蛭石用量和交联剂用量对复合高吸水树脂吸水溶胀性能的影响,并采用FTIR、XRD、SEM、TG对复合高吸水树脂的结构、形貌和热稳定性进行了表征,探讨了可能的引发聚合机理。结果表明,VMT表面的羟基与AMPS和AA中的CC键发生接枝共聚形成了无机/有机无定形共聚物,该材料表面呈现粗糙、多孔的结构,热稳定性良好,GDEP引发是一个自由基引发的链增长过程。     

辉光放电电解等离子体法制备VMT/P(AMPS-co-AA)高吸水树脂

在水溶液中,以蛭石(VMT)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)和丙烯酸(AA)为原料,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,用辉光放电电解等离子体(GDEP)引发制备蛭石/聚(2-丙烯酰胺-2-甲基丙磺酸-co-丙烯酸)(VMT/P(AMPS-co-AA))复合高吸水树脂。考察了放电电压、放电时间、蛭石用量和交联剂含量对复合高吸水树脂吸水溶胀性能的影响,用FT-IR、XRD、TG、SEM对复合高吸水树脂的结构、形貌和热稳定性进行了表征,同时探讨了可能的引发聚合机理。结果表明, VMT 表面的羟基与AMPS和AA中的C=C键发生接枝共聚形成了无机/有机无定形共聚物,该材料表面呈现粗糙、多孔的三维网状结构,热稳定性良好,GDEP引发是一个自由基引发的链增长过程。     

羧甲基纤维素/聚乙二醇/丙烯酸高吸水性复合材料的性能测试

在水溶液中,以丙烯酸(AA)、羧甲基纤维素(CMC)和聚乙二醇(PEG)为原料,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,用辉光放电电解等离子体(GDEP)技术引发制备羧甲基纤维素/聚乙二醇/丙烯酸(CMC/PEG/AA)高吸水性复合材料。考察了温度、pH、盐浓度对复合材料平衡溶胀率的影响,初步研究了复合材料对染料亚甲基蓝的吸附行为。结果表明,CMC/PEG/AA高吸水性复合材料在30℃蒸馏水中的最大溶胀率达到1 115 g/g;该复合材料具有pH敏感性、盐敏感性和可逆溶胀-消溶胀开关行为;其对亚甲基蓝的吸附量可达1 878.8 mg/g,吸附行为遵循动力学拟二级模型。     

γ-聚谷氨酸/凹凸棒石复合高吸水树脂的制备及性能

以γ-聚谷氨酸(γ-PGA)和凹凸棒石(ATP)为原料,以聚乙二醇二缩水甘油醚为交联剂,制备了γ-聚谷氨酸/凹凸棒石复合高吸水树脂,采用FTIR和SEM对其形貌和结构进行了表征。考察了γ-聚谷氨酸质量分数和凹凸棒石用量对复合高吸水树脂溶胀度的影响,发现当γ-PGA的质量分数为14%,ATP用量为6%(以γ-PGA的质量计,下同)时,样品在蒸馏水中的溶胀度较高,为820 g/g。同时,考察了溶液pH、NaCl质量分数、ZnCl_2质量分数和Na_2SO_3质量分数对复合树脂溶胀行为的影响,结果表明,适宜的pH为5～9;溶液中离子的质量分数越低,复合高吸水树脂的溶胀度越大;ZnCl_2溶液对树脂溶胀行为影响较大。此外,复合高吸水树脂具有较好的保水性能。     

P(AA-co-AMPS)/Kaolin复合高吸水树脂的制备及结构性能研究

以丙烯酸(AA)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和高岭土(Kaolin)为原料,采用溶液聚合法分别制备出聚丙烯酸(PAA)高吸水树脂、聚(丙烯酸-co-2-丙烯酰胺基-2-甲基丙磺酸)(P(AA-co-AMPS))高吸水树脂、P(AA-co-AMPS)/Kaolin复合高吸水树脂,并通过傅里叶变换红外光谱、扫描电镜、X射线衍射等测试方法对其结构与性能进行表征。结果表明:Kaolin与P(AA-co-AMPS)高吸水树脂之间为物理共混;PAA高吸水树脂、P(AA-co-AMPS)高吸水树脂和P(AA-co-AMPS)/Kaolin复合高吸水树脂的吸水倍率分别为231,323,357 g/g,吸盐水倍率分别为35.6,64.1,66.4 g/g,保水率分别为51.3%,55.6%,57.9%,凝胶形变量分别为3.75,4.10,2.23 mm;树脂的吸水速率由小到大依次为PAA高吸水树脂、P(AA-co-AMPS)高吸水树脂、P(AA-co-AMPS)/Kaolin复合高吸水树脂。     

纤维素基纳米复合材料对亚甲基蓝的吸附及解吸性能

采用FTIR和SEM对纤维素-g-聚丙烯酸/丙烯酰胺/蒙脱土(LNC-g-PAA/AM/MMT)纳米复合高吸水性树脂的结构进行表征。研究亚甲基蓝染料的初始质量浓度、吸附时间、吸附温度和pH等不同条件下,对LNC-gPAA/AM/MMT吸附该染料吸附量的影响。此外,在最佳条件吸附饱和时,改变解吸时间、HCl浓度等研究LNC-gPAA/AM/MMT的解吸性能。结果表明:初始质量浓度为2 500 mg/L,120 min,30℃,pH=5时,LNC-g-PAA/AM/MMT的吸附量高达2 038.7 mg/g。整个过程很好地符合伪二级动力学模型和Langmuir等温线。在解吸时间120 min,HCl浓度0.05 mol/L时,解吸率高达73.16%。     

高吸水性树脂对铅离子的吸附性能研究

本文所用到的高吸水树脂以马铃薯渣为母体,丙烯酸、丙烯酰胺为单体,采用过硫酸钾为引发剂,N-N′-亚甲基双丙烯酰胺为交联剂,氢氧化钠为中和剂制成的高吸水树脂。详细研究了吸附剂的吸附性能,确定吸附剂的最优吸附条件。通过对铅离子的吸附性能研究,结果表明:配比不同的高吸水树脂对同一浓度铅离子的吸附实验可知,配比为40%的高吸水树脂对浓度为5μg/mL铅离子的吸附最好,吸光度为0.243,实际浓度为5μg/mL,吸附铅离子的量为1.900;通过中和度为40%的高吸水性树脂(40~60目)对不同浓度铅离子的吸附实验可知,配比为40%的高吸水树脂对浓度为6μg/mL铅离子的吸附最好,吸光度为0.098,吸附铅离子的量为10.805;通过粒径不同的树脂对吸附的影响实验可知,粒径为20~40目的高吸水树脂对浓度为5μg/mL铅离子的吸附最好,吸光度为0.236,实际浓度为5μg/mL,吸附铅离子的量为2.892。     

GG-g-PAA/LOESS复合高吸水性树脂的制备与性能

以瓜尔胶(GG)、丙烯酸(AA)和黄土(LOESS)为原料,过硫酸铵(APS)为引发剂,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,采用水溶液聚合法制备了瓜尔胶接枝聚丙烯酸/黄土(GG-g-PAA/LOESS)复合高吸水性树脂。采用FTIR和SEM对其结构进行了表征,研究了LOESS的添加量对复合高吸水性树脂的溶胀能力和溶胀动力学的影响,考察了复合高吸水性树脂的保水性能、反复溶胀性以及在不同pH溶液中的吸水性能。结果表明,瓜尔胶、丙烯酸和LOESS发生了接枝共聚,体系中引入LOESS能够显著提高复合高吸水性树脂的吸水性能。当LOESS的质量分数为2%时,该树脂最高吸水倍率可达602 g/g,室温下6 d后,其保水率仍达28%,5次反复溶胀,吸水倍率仍能保持初始时的49%。此外,该复合高吸水性树脂还表现出优异的pH稳定性。     

硼吸附树脂合成及其在海水淡化中应用的研究

海水淡化中硼含量超标问题已经成世界性难题。本文合成一种含葡甲胺(MG,即N—甲基葡糖胺)新型氯球树脂用于硼的吸附与分离、即(PS-CL-MG),采用电子显微镜(SEM)和傅里叶红外光谱(FTIR)对树脂进行表征。系统的从投加量、pH、再生性考察PS-CL-MG吸附性能,并且建立海水淡化中硼的吸附动力学和吸附热力学模型。研究结果表明:pH值在9~10,PS-CL-MG对硼的吸附效果最好,该吸附剂吸附-解吸6次以后,吸附效率稳定35%~45%,对初始浓度为1 mg/L时含硼溶液,平衡吸附量为22.09μg/g。     

Synthesis and properties of a novel superabsorbent polymer composite from microwave irradiated waste material cultured Auricularia auricula and poly (acrylic acid‐co‐acrylamide)

A novel superabsorbent polymer composite was successfully synthesized from waste material cultured Auricularia auricula (WMCAA) and poly (acrylic acid‐co‐acrylamide) (P(AA‐co‐AM)) using microwave irradiation. Optimal synthesis conditions were determined by investigating the water absorbency of the superabsorbent composite. The effects associated with weight ratios of WMCAA, acrylamide (AM) monomers, initiators, and acrylic acid (AA) crosslinkers, as well as the degree of neutralization of AA were examined. The maximum water absorbencies were found to be 1548 g/g (distilled water) and 72 g/g (0.9% NaCl solution). Fourier transform infrared spectroscopy (FTIR) was applied to determine the molecular structure of the superabsorbent composite, and scanning electron microscopy (SEM) was used to demonstrate the characteristic compact and porous structure of the material. Further studies conducted via transmission electron microscopy (TEM) revealed the formation of a novel interpenetrating polymer network structure. Thermogravimetry/differential thermal (TG/DTG) analysis demonstrated improved thermal stability in the composite material compared with WMCAA. Additionally, high water absorption rates observed in the polymer during the swelling process indicated first‐order kinetics. The water absorption and adsorption of the superabsorbent composite were studied in a variety of fertilizer solutions, revealing an indirect relationship between water absorbing ability and fertilizer concentration. Conversely, a direct relationship was observed between absorbed fertilizer and fertilizer concentration. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3674–3681, 2013     

Porous Carrageenan-<Emphasis Type="Italic">g</Emphasis>-polyacrylamide/bentonite superabsorbent composites: swelling and dye adsorption behavior

A novel superabsorbent composite based on kappa-Carrageenan (κC) was prepared by graft copolymerization of acrylamide (AAm) onto κC in the presence of bentonite powder using methylenebisacrylamide (MBA) as a crosslinking agent, ammonium persulfate (APS) as an initiator, and sodium carbonate as a pore-forming agent. The swelling behavior in distilled water and in solutions with different pH values was investigated. The results indicated that with increasing carrageenan/bentonite weight ratio, the swelling capacity is increased but the gel content is decreased. The swelling rate of the hydrogels was improved by introducing sodium carbonate as pore-forming agent. The prepared superadsorbent composites were used as adsorbent for a cationic dye, methylene blue. Isotherm of adsorption and the effect of pH, adsorption dosage, contact time and initial dye concentration on dye adsorption were also studied. The results showed that maximum adsorption capacity of methylene blue on the prepared adsorbents is 156.25 mg g^?1 and adsorption is well-described by Langmuir isotherm model.     

The Effect of MMT/Modified MMT on the Structure and Performance of the Superabsorbent Composite

Summary A series of superabsorbent composites containing Montmorillonite (MMT), modified- Montmorillonite (OMMT) and sodium acrylate were synthesized by free-radical polymerization in aqueous solution. The structure of composites was characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and X-ray diffraction (XRD), and the results showed that the polymer chains were grafted onto the edge and the surface of MMT or OMMT. At the same time, the equilibrium swelling ratio of the composites was investigated as a function of the clay content and the results showed that the equilibrium swelling ratio of composites was improved by the introduction of clay. The maximum equilibrium swelling ratio of composite in distilled water and 0.9 wt% sodium chloride solutions were up to 2450 g/g and 118 g/g, respectively. Finally, the result of thermogravimetric analysis (TGA) suggested that the introduction of clay and modified clay could improve the thermal stability of superabsorbent composites.     

A superabsorbent hydrogel network based on poly((2-dimethylaminoethyl) methacrylate) and sodium alginate obtained by γ-radiation: synthesis and characterization

In this study, the synthesis and characterization of a novel nano-porous superabsorbent hydrogel with high water swelling capacity is described. A nano-porous hydrogel was prepared by employing (2-dimethylaminoethyl) methacrylate (PDMAEMA) as a pH sensitive monomer and sodium alginate (SA) as a water soluble polysaccharide under ??-ray irradiation. The polymerization reaction was performed at room temperature in the absence of chemically toxic crosslinking agent and initiators. The interactive parameters including biopolymer backbone concentration, monomer concentration and ??-irradiation dose were selected as major factors in the synthesis of superabsorbent and three levels for each factor were applied to obtain the highest water swelling according to the central composite design (CCD) method. According to the results of nine different tests which were derived by CCD method, the optimum conditions were determined. The results showed that the hydrogel prepared at concentration of 1.5?g SA, 2.1?mol/L PDMAEMA and at a radiation dose of 5?kGy displayed the highest swelling capacity. In continuation, the effect of salt, pH, and particle size on the swelling behavior of the obtained samples was investigated. We found that the swelling of the optimized sample first increased and then dropped with increases in pH from 2 to 12 and the maximum water absorbency was observed at pH 7. Finally, different techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscope (SEM) were applied for the characterization of optimized nano-porous hydrogel.     

Removal of methyl orange from aqueous solutions with poly(acrylic acid-co-acrylamide) superabsorbent resin

Poly(acrylic acid-co-acrylamide) (P(AA-co-AM) superabsorbent resin was prepared by solution polymerization of acrylic acid (AA) and acrylamide (AM) using ammonium persulfate (APS) as an initiator and N,N′-methylenebisacrylamide (MBA) as a cross linker. P(AA-co-AM) was used for the removal methyl orange (MO) from aqueous solutions. Factors influencing the adsorption capacity, such as adsorption time, initial concentration of MO, dosage of the superabsorbent resin, pH value and ionic strength, were investigated in detail. It was found that P(AA-co-AM) was effective to remove MO from its aqueous solutions. The equilibrium adsorption capacity was 394.6 mg/g at room temperature as the initial concentration of MO was 3000 mg/L. The mechanism of the adsorption process was also speculated. Study on the equilibrium adsorption isotherms showed that the adsorption was in accordance with both Langmuir and Freundlich model. Further study of the adsorption kinetics showed that the adsorption process was consistent with the Pseudo second-order kinetic model.     

Poly(Acrylamide-Sepiolite) Composite Hydrogels: Preparation, Swelling and Dye Adsorption Properties

Summary Polymer-clay hydrogel composite was prepared on the basis of polyacrylamide (PAAm) gel containing the clay mineral sepiolite. The properties of swelling and dye adsorption of poly(acrylamide-sepiolite) (AAm/Sep) composite hydrogel were investigated. The parameters of swelling and diffusion in water and dye solutions were calculated for the AAm and AAm/Sep hydrogels. It was found that the equilibrium swelling degree of obtained composite higher than that of AAm gel. Spectroscopic analysis of composite and composite-dye systems was done with FT-IR method. Adsorption of monovalent cationic dyes such as Basic Blue 12 (BB-12) Basic Blue 9 (BB-9), and Basic Violet 1 (BV-1), was studied on the composite. In the adsorption experiments, S (Sigmoidal) type for composite gel adsorption isotherms in the Giles classification system was found. Adsorption studies indicated that the amounts of adsorbed dyes on the AAm/Sep composite hydrogel were increased with following order; BB-12 > BB-9 > BV-1. The composite hydrogel may be considered as good candidate for environmental application to retain more water and dyes.     

Adsorption of anionic dyes on a reversibly swelling cationic superabsorbent polymer

A cationic monomer [2‐(methacryloyloxy)ethyl]trimethylammonium chloride was polymerized using N,N′‐methylenebisacrylamide as the crosslinker to obtain a cationic superabsorbent polymer (SAP). This SAP was characterized by Fourier transform‐infrared spectroscopy, and the equilibrium swelling capacity was determined by swelling in water. The SAP was subjected to cyclic swelling/deswelling in water and NaCl solution. The conductivity of the swelling medium was monitored during the swelling/deswelling and was related to the swelling/deswelling characteristics of the SAP. The adsorption of five anionic dyes of different classes on the SAP was carried out and was found to follow the first‐order kinetics. The Langmuir adsorption isotherms were found to fit the equilibrium adsorption data. The dye adsorption capacity of the SAP synthesized in this study was higher than that obtained for other hydrogels reported in the literature. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of superabsorbent hydrogels composites based on polysuccinimide

A kind of novel superabsorbent hydrogel with high swelling ratio property that could be used for the development of water absorbing resin, soil water retention agent, and chemical sand‐fixing material was synthesized in this study. The hydrogels were prepared by the crosslinking reaction of polysuccinimide (PSI). The relationships between swelling ratio and volume of solvent as well as the concentration of crosslinking agent were investigated in detail. Several composites, such as starch, carrageenan, and polyacrylamide, were added into hydrogels to enhance the swelling ratio. It was found that the swelling ratio was significantly increased, which the maximum water absorbency was enhanced 2.46 times when the composite polyacrylamide (PAM) was added compared to the control. The effects of ionic strength and sensitivity of pH on hydrogels were also studied. The modified hydrogels products with swelling ratio less sensitivity to the salinity as well as relative high swelling ration in salinity system were also obtained by adding PAM. Through the Fourier transform infrared spectroscopy (FTIR) characterizations, the crosslinking reaction mechanism and the structure of composite were proposed. In addition, the transmission electron microscopy (TEM) examinations showed that some composite materials elevated the physical crosslinked and connected channels density substantially. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 550–557, 2006     

Adsorption of cationic dyes on poly(acrylic acid‐co‐sodium acrylate‐co‐acrylamide) superabsorbents

Inverse suspension polymerization was carried out to synthesize poly(acrylic acid‐co‐sodium acrylate‐co‐acrylamide) superabsorbent polymers (SAPs) crosslinked with ethylene glycol dimethacrylate (EGDMA). The equilibrium swelling capacities of the SAPs, determined by swelling them in DI water, were found to vary with the acrylamide (AM) content. The SAPs were used to adsorb four cationic dyes (Acriflavine, Auramine‐O, Azure‐I and Pyronin‐Y). The effect of AM content in the SAPs on the adsorption of the cationic dyes was investigated. Different initial concentrations of Azure‐I were used with the same amount of the SAP to explore the effect of initial dye concentration on the adsorption. The effect of the adsorbent amount was investigated by taking different amounts of SAP with a fixed initial concentration of Acriflavine. The kinetics of the dye adsorption was modeled by a first order model and the equilibrium amount of the dye adsorbed, adsorption rate coefficients, removal efficiency and partition coefficients were determined. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012