Water uptake and dye sorption studies of chemically crosslinked highly swollen novel ternary acrylamide‐based hydrogels including citraconic acid and sodium acrylate

Highly swollen hydrogels made by the polymerization of acrylamide (AAm) with some anionic monomers such as citraconic acid (CITA) and sodium acrylate (SA) were investigated as a function of composition to find materials with swelling and dye sorption properties. Highly swollen AAm/CITA/SA or AAm/SA/CITA hydrogels were prepared by free radical solution polymerization in aqueous solutions of AAm with CITA and SA as co‐monomers and two multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and 1,4‐butanediol dimethacrylate (BDMA). Swelling experiments were performed in water at 25°C, gravimetrically. Chemically crosslinked AAm/CITA/SA or AAm/SA/CITA hydrogels were used in experiments on sorption of water‐soluble monovalent cationic dye such as “Nil blue” (Basic Blue 12; BB 12). Equilibrium percentage swelling values of AAm/CITA/SA or AAm/SA/CITA hydrogels were calculated in the range of 1797–22,098%. Some swelling kinetic parameters were found. Diffusion behavior of water was investigated. Water diffusion into the hydrogels was found to be non‐Fickian in character. For sorption of cationic dye, BB 12 into the hydrogels was studied by batch sorption technique at 25°C. AAm/CITA/SA or AAm/SA/CITA hydrogels in the dye solutions showed coloration, whereas AAm hydrogel did not show sorption of any dye from the solution. The sorption capacity of AAm/CITA/SA or AAm/SA/CITA hydrogels was investigated. At the end of the experiments, 21.70–78.91% BB 12 adsorptions were determined. Copyright © 2007 John Wiley & Sons, Ltd.     

Uptake of Basic Blue 17 from aqueous solutions by using chemically crosslinked polyelectrolyte AAm/AASS hydrogels

In this study, the removal of a cationic thiazin dye such as Basic Blue 17 (Toluidin Blue, BB 17) by chemically crosslinked acrylamide (AAm)/acrylic acid sodium salt (AASS) hydrogels was investigated. Super water retainer AAm/AASS hydrogels with various compositions were prepared from ternary mixtures of AAm, AASS and water by free radical polymerization in aqueous solution using multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA), N,N′ methylenebisacrylamide (NMBA), 1,4 butanediol dimethacrylate (BDMA) and trimethylolpropane triacrylate (TMPTA). Adsorption of Basic Blue 17 from aqueous solutions was studied by batch sorption technique at 25^°C. The effect of Basic Blue 17 concentration and mass of adsorbent on the dye adsorption were examined. In the experiments of the sorption, C type and L type sorption in the Giles classification system was found. Some binding parameters such as initial binding constant (K _i ), equilibrium constant (K), monolayer coverage (n), site-size (u), and maximum fractional occupancy (Ô) for AAm/AASS hydrogel-dye binding system were calculated by using Klotz linearization method. Finally, the amount of sorbed Basic Blue 17 per gram of dry hydrogel (q) was calculated to be 1.96–21.35 μ mol dye per gram for AAm/AASS hydrogels. Adsorption of Basic Blue 17 was changed range 39.17–96.63%. AAm/AASS hydrogels crosslinked by TMPTA, EGDMA, BDMA or NMBA can be used a sorbent in biotechnology, environment, sorption, separation, purification, immobilization and enrichment of some species.     

Cationic dye adsorption by acrylamide/itaconic acid hydrogels in aqueous solutions

Acrylamide/itaconic acid (AAm/IA) hydrogels containing different quantities of itaconic acid have been irradiated with γ radiation. The hydrogels were used in an experiment concerning the adsorption of cationic dyes such as Basic Blue 9, Basic Violet 1 and Basic Blue 12. In the experiments of the adsorption of dyes from their synthetic aqueous solutions, type S adsorption isotherms were found. One mole of monomeric unit of AAm/IA hydrogels adsorbed 78.5–513.1 μmole of Basic Blue 9, 60.2–641.1 μmole of Basic Violet 1 and, 28.8–593.3 μmole of Basic Blue 12, while acrylamide hydrogel did not adsorb any cationic dye. As a result, it was shown that the AAm/IA hydrogels could be used as an adsorbent for water pollutants such as dyes, and immobilization of these organic contaminants in the hydrogels from waste water can solve one of the most important environmental problems of the textile industry. © 1997 John Wiley & Sons, Ltd.     

Synthesis of poly (acrylamide-co-aconitic acid) adsorbents by gamma-irradiation,characterization, adsorption studies and application for cationic dyes removal

In this study, acrylamide (AAm)/aconitic acid (ACA) copolymers were prepared with two different mol% of aconitic acid 4%, 17% and were irradiated with gamma irradiation at different irradiation doses (4 - 25kGy). The percent yield was assigned by gravimetrical method. The effect of irradiation dose, pH and involved amounts of monomers (AAm/ACA) in hydrogels on swelling properties were investigated. The conversion of monomers to hydrogels was 100% at 25kGy. Poly(acrylamide-co-aconitic acid) P(AAm/ACA) hydrogels have been used for the adsorption of some aqueous solutions of dyes such as Methylene Blue (MB) and Safranine-O (S). The hydrogels were swollen in distilled water at pH 3, 5, 7, 8 and in aqueous solutions of dyes. The initial swelling rates of hydrogels are increased by increasing of pH. The effects of concentration of the aqueous solutions of dye and hydrogel composition on the adsorption were investigated. The adsorption is increased and changed depending on the structure of dye and composition of hydrogel.     

Novel Cationic Poly[AAm/NVP/DAPB] Hydrogels for Removal of Some Textile Anionic Dyes from Aqueous Solution

Novel cationic poly [AAm/NVP/DAPB] hydrogels (YH₁ – YH₅) were synthesized by free radical solution polymerization of AAm, NVP and DAPB by increasing the concentration of DAPB in the feed. According to swelling experiments, hydrogel YH₅ with higher DAPB content gave relative higher swelling percentage compared to other hydrogels. The hydrogel YH₅ was characterized by FTIR, TGA and SEM analysis. The anionic dye solution such as Orange-II, Reactive Golden Yellow and Acid Yellow were used as an adsorption medium to investigate the usability of the hydrogel for the removal of anionic dyes. The effect of pH of the adsorption medium, initial concentration of the dye, adsorbent dose, %swelling and contact time was also investigated. Furthermore, the Langmuir and Freundlich adsorption isotherms were applied and they showed a good fit to the experimental data. From the results, the uptake of dyes within the hydrogel increased in the following order: Reactive Golden Yellow>Orange-II>Acid Yellow.     

Aam/Aac水凝胶对碱性藏花红染料的吸附特性研究

以丙烯酰胺(AAm)、丙烯酸(AAc)合成了单体配比分别为1，2、1／1、2，1的AAm/AAcc水凝胶，采用分光光度计法研究了此水凝胶对水溶性单价阳离子染料碱性藏花红的吸附特性，测定了它们的吸附动力学曲线和吸附等温线：探讨了水凝胶单体组成对该染料吸附性能的影响：并且用静电场理论解释了解吸后水凝胶更优的再吸附特性，研究表明，AAm，AAc水凝胶可作为染料污水处理中一种良好的吸附剂。     

Super Absorbent Hydrogel Based on Poly[acrylamide/maleic acid/2-methacryloxy ethyl trimethylammonium chloride]: Synthesis,Characterization and their Application in the Removal of Chromium (VI) from Aqueous Solution

New poly[acrylamide/maleic acid/2-methacryloxy ethyl trimethylammonium chloride], poly[AAm/MA/METAC], super absorbent hydrogels (M1-M4) were prepared via microwave irradiated free radical solution polymerization using different compositions. According to swelling experiments, hydrogel M1 with higher METAC content gave relatively higher swelling percentage compared to other hydrogels. The hydrogel M1 was characterized by FT-IR, TGA, and SEM analysis. The influence of the uptake conditions such as pH, time, adsorbent dose and initial feed concentration on the metal ion binding capacity of hydrogel was also tested. Furthermore, the Langmuir and Freundlich adsorption isotherms were applied and they showed a good fit to the experimental data.     

Cationic dye adsorption by poly(N-isopropylacrylamide/maleic acid) copolymeric hydrogels prepared by gamma rays

N-isopropylacrylamide/maleic acid hydrogels containing different quantities of maleic acid have been synthesized with γ-radiation. The hydrogels were used in experiments on swelling, diffusion and adsorption of a cationic dye methylene blue. The diffusion of MB into the hydrogels was found to be the non-Fickian type. The factors influencing adsorption capacity of the hydrogel such as gel composition, and irradiation dose were systematically investigated. The equilibrium data for dye adsorption was better described by the Freundlich isotherm than Langmuir isotherm model. The kinetic studies showed that the pseudo-second-order kinetic model fits better than the data obtained from pseudo-first-order model.     

(Sodium Alginate/Acrylamide) Semi‐Interpenetrating Polymer Networks and their Usability on Removal of Lead,Cadmium, Nickel Ions

In this study, (sodium alginate (NaAlg)/acrylamide (AAm)) interpenetrating polymer networks (IPN) have been prepared at three different compositions, where the sodium alginate composition varies 1, 2, and 3% (w/v) in 50% (w/v) acrylamide solutions. These solutions have been irradiated with a ⁶⁰Co‐γ source at different doses. The percent conversion was determined gravimetrically and 100% gelation was achieved at the 10.0 kGy dose. The swelling results at pH 7.0 and 9.0 indicated that (NaAlg/AAm)3IPN hydrogel, containing 3% NaAlg showed maximum % swelling in water, with swelling increasing in the order of Ni²⁺>Cd²⁺>Pb²⁺. Diffusion in aqueous solutions of metal ions within (NaAlg/AAm)IPN hydrogels was found to be Fickian character. Diffusion coefficients of (NaAlg/AAm)IPN hydrogels in water and aqueous solutions of metal ions were calculated. The maximum weight loss temperature and half life temperature for NaAlg, PAAm, (NaAlg/AAm)IPN and (NaAlg/AAm)IPN‐metal ion systems were found from thermal analysis studies. In the adsorption experiments, the efficiency of (NaAlg/AAm)IPN hydrogels to adsorb nickel, cadmium and lead ions from water was studied. (NaAlg/AAm)IPN hydrogels showed different adsorption for different aqueous solution of metal ion at pH 7.0. Adsorption isotherms were constructed for the (NaAlg/AAm)IPN‐metal ion systems. S type adsorption in the Giles classification system was found.     

Removal of cationic dyes by poly(acrylamide-co-acrylic acid) hydrogels in aqueous solutions

Poly(acrylamide-co-acrylic acid (poly(AAm-co-AAc)) hydrogels prepared by irradiating with γ-radiation were used in experiments on swelling, diffusion, and uptake of some cationic dyes such as Safranine-O (SO) and Magenta (M). Poly(AAm-co-AAc) hydrogels irradiated at 8.0 kGy have been used for swelling and diffusion studies in water and cationic dye solutions. The maximum swellings in water, and SO, and M solutions observed are 2700%, 3500%, and 4000%, respectively. Diffusions of water and cationic dyes within hydrogels have been found to be non-Fickian in character. Adsorption of the cationic dyes onto poly(AAm-co-AAc) hydrogels is studied by the batch adsorption technique. The adsorption type was found Langmuir type in the Giles classification system. The moles of adsorbed dye for SO and M per repeating unit in hydrogel (binding ratio, r) have been calculated as 3834×10⁻⁶ and 1323×10⁻⁶, respectively. These results show that poly(AAm-co-AAc) hydrogels can be used as adsorbent for water pollutants such as cationic dyes.     

The effect of external stimuli on the Bovine Serum Albumin adsorption capacity of poly(acrylamide/maleic acid) hydrogels prepared by gamma rays

The effects of external stimuli such as pH of the buffer solution, ionic strength, temperature and the amount of poly-electrolyte monomer in the hydrogel system on the Bovine Serum Albumin (BSA) adsorption capacity of poly(acrylamide/maleic acid) [P(AAm/MA)] hydrogels were investigated. Poly-electrolyte P(AAm/MA) hydrogels with varying compositions were prepared by irradiating acrylamide/maleic acid/water mixtures with γ rays at ambient temperature. Langmuir type adsorption isotherms were observed for all prepared hydrogels. Increase of ionic strength of the buffer solution from 0.01 to 0.1 mol dm⁻³ decreased the adsorption capacity of hydrogels and zero adsorption was observed in the presence of 0.1 mol dm⁻³ Na⁺ and Ca²⁺ ion in the adsorption medium. The adsorption capacity of hydrogels was found to increase from 0 to 120 mg BSA/g dry gel, by changing external stimuli and hydrogel composition.     

Dye removal by a novel hydrogel‐clay nanocomposite with enhanced swelling properties

Acrylamide (AAm)‐2‐acrylamide‐2‐methylpropanesulfonic acid sodium salt (AMPSNa) hydrogel and AAm‐AMPSNa/clay hydrogel nanocomposite having 10 w% clay was prepared by in situ copolymerization in aqueous solution in the presence of a crosslinking agent (N,N′‐methylenebisacrylamide (NMBA)). Swelling properties and kinetics of the hydrogel samples were investigated in water and aqueous solutions of the Safranine‐T (ST) and Brilliant Cresyl Blue (BCB) dyes. The swelling and diffusion parameters were also calculated in water and dye solutions. It was observed that the AAm‐AMPSNa/clay hydrogel nanocomposite exhibits improved swelling capacity compared with the AAm‐AMPSNa hydrogel. It was also found that the diffusion mechanisms show non‐Fickian character. Adsorption properties of the hydrogel samples in the aqueous solution of ST and BCB dyes were also investigated. Clay incorporation into the hydrogel structure increased not only the adsorption capacity but also the adsorption rate. Adsorption capacity values of the hydrogel nanocomposite were found to be 484.2 and 494.2 mg g^?1 for the ST and BCB dyes, respectively. It was seen that the adsorption of dyes by the hydrogel nanocomposite completed in 10 min while the AAm‐AMPSNa hydrogel adsorbed dyes approximately in 90 min. Adsorption data of the samples were modelled by the pseudo‐first‐order and pseudo‐second‐order kinetic equations in order to investigate dye adsorption mechanism. It was found that the adsorption kinetics of hydrogel nanocomposite followed a pseudo‐second‐order model. Equilibrium isotherms were analyzed using the Langmuir and Freundlich isotherms. It was seen that the Langmuir model fits the adsorption data better than the Freundlich model. Copyright © 2008 John Wiley & Sons, Ltd.     

Swelling characterization of novel ternary semi‐IPNs: acrylamide/1‐vinylimidazole/PEG hydrogels

New ternary semi interpenetrating polymer networks (semi‐IPNs) systems containing acrylamide (AAm), 1‐vinylimidazole (VI) and poly (ethylene glycol) (PEG) have been prepared. AAm/VI hydrogels and semi‐IPN's, poly (AAm/VI/PEG) with 0.25, 0.50, 0.75 and 1.00 g of PEG (per 1.00 g AAm) were prepared by free radical solution polymerization in aqueous solution of AAm with VI as comonomer and a multifunctional crosslinker such as 1,4 butanediol dimethacrylate (BDMA). Swelling experiments were performed in water at 25°C, gravimetrically. The influence of VI and PEG content in hydrogels were examined. AAm/VI and AAm/VI/PEG hydrogels showed large extents of swelling in aqueous media, the swelling being highly dependent on the chemical composition of the hydrogels. Percentage swelling ratio of AAm/VI hydrogels and AAm/VI/PEG hydrogels was shown as 650–4167%. The values of equilibrium water content (EWC) of the hydrogels are between 0.8990 and 0.9750. Diffusion behavior was investigated. Water diffusion into hydrogels was found to be non‐Fickian in character. Copyright © 2007 John Wiley & Sons, Ltd.     

Adsorption of Uranyl Ions into Poly(Acrylamide‐co‐Acrylic Acid) Hydrogels Prepared by Gamma Irradiation

Acrylamide (AAm)/Acrylic Acid (AAc) copolymers have been prepared by gamma irradiation of binary mixtures at three different compositions where the acrylamide/acrylic acid mole ratios varied around 15, 20, and 30%. Threshold dose for 100% conversion of monomers into hydrogels was found to be 8.0 kGy. Poly(Acrylamide‐co‐Acrylic Acid) (poly(AAm‐co‐AAc)) hydrogels have been considered for the removal of uranyl ions from aqueous solutions. Swelling behavior of these hydrogels was determined in distilled water at different pH values and in aqueous solutions of uranyl ions. The results of swelling tests at pH 8.0 indicated that poly(AAm‐co‐AAc) hydrogel, containing 15% acrylamide showed maximum % swelling. Diffusion of water and aqueous solutions of uranyl ion into hydrogels was found to be non‐Fickian in character and their diffusion coefficients were calculated. The effect of pH, composition of hydrogel, and concentration of uranyl ions on the adsorption process were studied at room temperature. It was found that one gram of dry poly(AAm‐co‐AAc) hydrogel adsorbed 70–320 mg and 70–400 mg uranyl ions from aqueous solutions of uranyl nitrate and uranyl acetate in the initial concentration range of 50–1500 mg UO₂ ²⁺L^?, depending on the amount of AAc in the hydrogels, respectively. Adsorption isotherms were constructed for poly(AAm‐co‐AAc)–uranyl ion system indicating an S type of adsorption in the Giles classification system. It is concluded that crosslinked poly(AAm‐co‐AAc) hydrogels can be successfully used for the removal of uranyl ions from their aqueous solutions.     

Adsorption of methyl violet in aqueous solutions by poly(N-vinylpyrrolidone-co-methacrylic acid) hydrogels

N-vinylpyrrolidone(VP)/methacrylic acid (MAA) monomer mixtures containing different quantities of methacrylic acid were irradiated with gamma-radiation to form hydrogels. Mixtures which contain 5, 10, 15% and irradiated with 3.4 kGy were used for swelling and diffusion studies in water and solutions of methyl violet and for the adsorption of methyl violet from aqueous solutions. Diffusion of water and methyl violet within hydrogels were found to be of non-Fickian character. In the dye adsorption experiments, the effects of pH, concentration of aqueous solution of dye and the composition of hydrogels on the adsorption process were investigated. When the pH and concentration of aqueous solutions of dye and the MAA content in hydrogels increased, the adsorption increased.     

Synthesis and characterization of thermoresponsive isopropylacrylamide-acrylamide hydrogels

In this study, hydrogels of poly(N-isopropylacrylamide-co-acrylamide) having a thermoresponsive character were prepared by a redox polymerization method. NIPAM-co-AAm hydrogels with different thermoresponsive properties were obtained by changing the initial NIPAM/AAm mole ratio and crosslinker concentration.Equilibrium-swelling ratio, dynamic swelling ratio and dynamic deswelling ratio were evaluated for all hydrogel systems. The fast shrinking was observed with all gels. The time required for equilibrium shrinking increased with the increase of acrylamide content in the gel.     

RADIATION INDUCED ACRYLAMIDE/CITRIC ACID HYDROGELS AND THEIR SWELLING BEHAVIORS

Citric acid (CAc) moieties containing acrylamide (AAm) hydrogels were prepared by gamma irradiation of their aqueous solutions. A possible polymerization and crosslinking mechanism for acrylamide/citric acid (AAm/CAc) hydrogels is proposed. The effects of irradiation dose and citric acid content on swelling behavior were investigated. Swelling took place in water at 25°C and was followed gravimetrically. Incorporation of a relatively low amount of citric acid to acrylamide hydrogel increased its swelling up to 950% from 700%. The diffusion of water into AAm/CAc hydrogels was found to be a non-Fickian type. Diffusion coefficients of AAm/CAc hydrogels found as 5 × 10^?7? 10 × 10^?7 cm² sec^?1. It has also been found that the number average molar mass between crosslinks is increased with the CAc content and decreased with irradiation dose.     

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%.     

Swelling behavior of strong polyelectrolyte poly(N-t-butylacrylamide-co-acrylamide) hydrogels

Temperature-sensitive ionic hydrogels based on N-t-butylacrylamide (TBA), acrylamide (AAm), 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS) and N,N^′-methylenebis(acrylamide) (BAAm) monomers were prepared. The molar ratio of TBA to the monomers AAm and AMPS was fixed at 60/40, while the AMPS content of the hydrogels was varied. The elastic modulus of the hydrogels was in the range of 347-447 Pa, much lower than the modulus of PAAm or poly(N-isopropylacrylamide) hydrogels due to the reduced crosslinking efficiency of BAAm in TBA/AAm copolymerization. The hydrogels exhibited swelling-deswelling transition in water depending on the temperature. Increasing ionic group (AMPS) content resulted in shifting of the transition temperature interval in which the deswelling takes place. The higher the ionic group content, the broader the temperature interval at the phase transition. Ionic hydrogels exhibited first-order reentrant conformational transitions in ethanol-water and in dimethylsulfoxide (DMSO)-water mixtures. The higher the ionic group content of the hydrogels the narrower the ethanol (or DMSO) range in which the reentrant phenomena occur. By taking into account the difference of the solvent mixture composition inside and outside the gel, the equilibrium swelling theory provided a satisfactory agreement to the experimental swelling data of the hydrogels immersed in the solvent mixtures.     

The Influence of Preparation Methods on the Swelling and Network Properties of Acrylamide Hydrogels with Crosslinkers

Abstract

Using different types and concentrations of crosslinkers, acrylamide (AAm) hydrogels have been prepared with chemical initiation and gamma irradiation techniques. The effects of the preparation method, crosslinkers type and concentration on swelling behavior of AAm hydrogels were investigated. Swelling was performed in distilled water and followed gravimetrically. Swelling parameters such as equilibrium swelling degree, equilibrium water content (EWC), maximum swelling, initial swelling rate, diffusion exponent and coefficient, and network parameters such as molecular mass between crosslinks, crosslink density, mesh size, and porosity were calculated and evaluated. The range of equilibrium swelling degree of AAm hydrogels was varied from 255% to 1450% depending upon the preparation method, crosslinker type, and crosslinker concentration. The diffusion of water into AAm hydrogels was found to be nonFickian.