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In this study, the cationic monomer [2-(acryloyloxy)ethyl]trimethylammonium chloride solution (AETAC) and vinyl imidazole (VI) were used with the free radical polymerization technique, which is a simple and rapid synthesis method, to synthesize p(AETAC-co-VI) hydrogels. To increase the density of cationic charge on the hydrogel, it underwent the protonation process with HCl. The obtained p(AETAC-co-VI)/Q hydrogel was modified with Au nanoparticles to increase bactericidal effect to obtain the AuNPs/p(AETAC-co-VI)/Q nanocomposite hydrogel. The morphology and chemical structure of the hydrogels were characterized with SEM and FTIR. Additionally, the swelling capabilities were tested in different pH media. XRD and TEM confirmed the formation of the nanocomposite hydrogel. The antibacterial activity of the hydrogels was tested against E. coli and S. aureus, and controlled release implementations were completed with sodium diclofenac (NaDc) drug. The NaDc drug release profiles of the hydrogels were researched using the Korsmeyer-Peppas model at 37 degrees C in different simulated buffer (pH 6.0, 7.2, and 8.0) solutions. It was found that both the hydrogel and nanocomposite hydrogel followed non-Fickian diffusion mechanisms as free release mechanism. Here, the maximum drug release efficacy was found to be 97%, and drug release was more rapid in basic media when release media were compared. The AuNPs/p(AETAC-co-VI)/Q nanocomposite hydrogels produced in this study with advanced antibacterial features were suitable for recommendation as good carriers for in vitro release of NaDc drugs in areas like the biomedical and pharmaceutical industries.

In this study, p(AAm-co-TACYC) hydrogels were synthesized using TACYC crosslinker. The p(AAm-co-TACYC) hydrogel was used for preparation of Cu(0) nanoparticles as support material. The p(AAm-co-TACYC)@Cu was prepared by chemical reduction of Cu2+ ions in the p(AAm-co-TACYC) networks and was structurally characterized in detail. Later the catalytic activity of p(AAm-co-TACYC)@Cu was investigated for hydrogen production from AB and EDAB hydrolysis. Detailed kinetic studies were performed for both hydrogen storage materials. The p(AAm-co-TACYC)@Cu was a more active catalyst for the EDAB hydrolysis reaction. The Ea values of p(AAm-co-TACYC)@Cu for the AB and EDAB hydrolysis reactions were determined as 68.36 kJ mol−1 and 39.07 kJ mol−1, respectively. In addition to the perfect catalytic activity of p(AAm-co-TACYC)@Cu, it had good reusability. After ten consecutive uses for AB and EDAB hydrolysis, the p(AAm-co-TACYC)@Cu still had 88% and 85% of initial activity, respectively.

In this study, hydroxyethyl starch (HES)-based hydrogels, hydroxyethyl starch/p(sodium acrylate) (HES/p(NaAAc)), hydroxyethyl starch/p(3-(acrylamidopropyl) trimethyl ammonium chloride) (HES/p(APTMACl)) and hydroxyethyl starch/p(acrylamide) (HES/p(AAm)) were synthesized with redox polymerization. The structural, morphological, and water absorption characterization of the synthesized hydrogels was investigated. HES-based hydrogels, containing anionic, cationic and neutral functional groups, were used for adsorption of methyl violet (MV) as a model cationic dye and methyl orange (MO) as a model anionic dye from aqueous media. HES/p(APTMACl) and HES/p(NaAAc) hydrogels had maximum adsorption values for MO and MV dyes of 238.1 mg/g and 185.2 mg/g. The isotherm and kinetic parameters for both dye adsorptions were determined. The adsorption isotherm and kinetic data were compatible with the Langmuir isotherm and pseudo-first-order kinetic models.

Poly((methacryloylamino)propyl trimethylammonium chloride-co-vinylimidazole) (p(MAPTAC-co-VI)) hydrogels were synthesized through free radical polymerization of 3-(methacryloylamino)propyl trimethylammonium chloride (MAPTAC) and 1-vinylimidazole (VI) in aqueous solutions with ammonium persulfate (APS) used as initiator and N,N′-methylenebis(acrylamide) (MBA) as the crosslinking agent. By modifying with HCl, the positive charge density on the hydrogel network structure was increased and quaternized hydrogels (p(MAPTAC-co-VI)-q) were obtained. Traditional swelling and spectrophotometric characterization techniques were used to gain a better understanding of the performance of cationic hydrogels for the removal of anionic dyes. FTIR, SEM, and EDX confirmed the structure of the hydrogel before and after the adsorption process. Later, dye adsorption performance of these p(MAPTAC-co-VI)-q hydrogels was investigated under different adsorption conditions, including initial concentration, temperature, pH values of dye solutions, and adsorption contact time, adsorbent dosage and in real water samples. Various isotherm and kinetic models of dye adsorption by the hydrogel were also studied and the experimental adsorption followed a pseudo-second order model and fitted the Langmuir isotherm well. Thanks to the effective use of existing adsorption sites, high adsorption capacity was achieved for eriochrome black T (EBT) and methyl orange (MO) dyes. The values of qmax are as follows: 1818.2 mg/g and 1449.3 mg/g, respectively. Thermodynamic parameters indicate that the process was spontaneous and endothermic. P(MAPTAC-co-VI)-q hydrogels can be used as a potential adsorbent for removal of anionic dye molecules, one of the industrial pollutants, from wastewater.

In this study, chitosan, an aminopolysaccharide, was reacted with phosphazene-derived crosslinker by Schiff-base reaction to yield crosslinked-chitosan hydrogel. Here, hexakis(4-formylphenoxy)cyclo...

This study used biocompatible and biodegradable hydroxyethyl starch (HES), 2-hydroxyethyl methacrylate (HEMA) and N-vinyle-2-pyrrolidone (NVP) monomers for hydrogel synthesis with the aim of use as a drug carrier system. As a result of the synthesis reactions using the redox polymerization technique, hydrogels were produced in both film and cylindrical form. The morphological characterization and structural characterization of hydrogels were performed using scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. In addition, swelling characterizations of hydrogels to be used for drug release in various media were examined. The release properties of sodium diclofenac (NaDc) and trimethoprim (TMP) loaded into hydrogels produced in order to use as drug carrier material for controlled drug release were examined in media with pH = 1.2 and 7. It was determined that the hydrogels performed controlled release according to the type of drug and the pH values of the medium. Drug release mechanisms deviated from Fickian mode according to determined drug release rate constants, diffusion exponent (n) and regression values at different pH values. In addition, antibacterial properties of drug-loaded hydrogels against B. subtilus, S. aureus and E. coli were investigated.

The present research offers an innovative cyclic approach to cleaning colored water of toxic dyes due to the increased need for pure and safe water. Novel anionic hydrogels were fabricated via free radical copolymerization method in the presence of acrylamide or 2-hydroxyethyl methacrylate as neutral comonomer and N-tert-butylmaleimic acid as anionic monomer with the addition of N , N ′-methylenebisacrylamide as cross-linker. Hydrogels were examined for morphology and chemical structure using SEM and FTIR analyses. The swelling and adsorption behavior of the hydrogels with different molar ratios were examined. The parameters affecting the adsorption of the model dyes of CV and MB onto the hydrogel were investigated such as initial concentration of dye, various comonomer ratios, dose of hydrogel, and temperature. The adsorption behavior was consistent with the Langmuir isotherm model. Also, the thermodynamic analysis and Dubinin-Radushkevich isotherm model revealed that the adsorption of the dyes onto hydrogels was applicable in a wide temperature range as well as with physical and weak chemical interactions. TBMAC-based hydrogels were found to be a cost-effective prospective candidate with great regeneration efficiency and selectivity to be used as an adsorbent to effectively remove hazardous dyes from industrial waste.

In this study, N-tert-butylmaleimic acid was designed for the first time and synthesized by reaction of maleic anhydride with tert-butylamine and evaluated as a new functional monomer for preparation of new pH-responsive hydrogels. Its structure was verified with FTIR, 1H and 13C NMR. A new pH- and temperature-responsive hydrogel p(TBMAC-co-NIPAM), based on TBMAC and NIPAM, was successfully prepared via free-radical copolymerization technique in an aqueous solution. The chemical and structural properties of the hydrogels were identified by FTIR and SEM. The swelling properties of these hydrogels were systematically investigated according to various parameters such as time, temperature, pH and salt effects, and the results show that they are strongly influenced by the content of TBMAC and exhibit strong pH, temperature and salinity sensitivity. In addition, swelling kinetics and water diffusion mechanisms in hydrogels were discussed. In addition, in vitro drug release studies were performed in simulated gastric, isotonic serum and intestinal fluid at two different temperatures (23 and 37 °C) by taking R6G as a model drug. Drug loading results were investigated with various isotherm models such as Langmuir, Freundlich, Temkin and Dubinin-Radushkevich. Various kinetic models such as zero-order, first-order, Higuchi model and Korsmeyer-Peppas models were applied to determine the drug release mechanism. The results indicated that drug release involves non-Fickian transport mechanism. These results suggest that this new pH- and thermo-responsive hydrogel may be used to improve sustained release of drugs.

In this study, firstly N-metacrylamido thiomorpholine containing thioether group was synthesized as monomer. Then, p(AAm-co-MTM) hydrogels were prepared from the redox polymerization of acrylamide and N-metacrylamido thiomorpholine as a selective support material. p(AAm-co-MTM) hydrogel-gold nanoparticles were obtained as a result of the reduction of the selectively absorbed gold(III) ions by the hydrogel network using NaBH4 as reducing agent. All materials were characterized using techniques such as SEM, EDX, TEM and XRD analysis. It was determined that p(AAm-co-MTM)-Au composite material has high catalytic activity for the reduction of 4-nitrophenol. The activation parameters of the reduction reaction of 4-nitrophenol using NaBH4 in the presence of p(AAm-co-MTM)-Au catalyst were calculated as Ea = 38.80 kJ/mol, ΔH# = 36.16 kJ/mol and ΔS#= −161.37 J/mol K.

As pharmaceutical carrier materials having antibacterial and pH-sensitive properties, hydrogels have great potential for clinical applications. Alginate based hydrogels were designed as an oral drug carrier and investigated for the drug release study in biomedical fields especially the colon-targeted system. Structural changes of synthesized hydrogel have been characterized using Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) devices. Hydrogels have been studied for their water absorption behavior under the influence of various monomer compositions and changing ambient conditions such as salt, pH and temperature. In this study, diclofenac sodium was used as a model drug to investigate the in vitro release behavior at simulated intestinal (pH 7.0) and gastric fluid (pH 1.2). Lastly, the antibacterial effect of hydrogels and drug-loaded hydrogels was characterized using a disc diffusion method against Gram-positive and Gram-negative bacteria. The suitability of controlled drug release for the use of these new hydrogels in the pharmaceutical and biomedical field has been investigated and our results have shown that the produced hydrogels are promising materials for developing pH-controlled drug delivery devices like capsules for oral use.

In this study, we synthesized a novel phosphazene compound hexakis[4-(acrylamido)phenoxy]cyclotriphosphazene (HAAP) as crosslinker. The structure of compound was identified using spectroscopic techniques. Then, HAAP was used as crosslinker for the synthesis of thermo and pH responsive p(NIPAM-co-VI) hydrogels. The structure and swelling behavior of hydrogel was investigated. Then, HAAP-crosslinked p(NIPAM-co-VI) hydrogels were used for in vitro release of Rhodamine 6G as drug release matrix. Additionally, HAAP-crosslinked p(NIPAM-co-VI) hydrogels were used as support material for the preparation of cobalt metal catalysts. The prepared HAAP-crosslinked p(NIPAM-co-VI)-Co composite catalyst was used as catalyst for the reduction reaction of 4-nitrophenol.

Within the scope of this study, p(2-hydroxyethyl methacrylate-co-tetraacrylic cyclen) (p(HEMA-co-TACYC)) hydrogels were synthesized for the first time in the literature using a tetraacrylic cyclen (TACYC) as both functional monomer and crosslinker. The hydrogels designed especially for Cu2+ ions showed colorimetric sensor behavior selective for Cu2+ ions in all aqueous media (deionized, tap, river and sea water) and in metal ion mixtures. The p(HEMA-co-TACYC) hydrogels forming a stable complex with Cu2+ ions simultaneously showed properties of being a good adsorbent material. The hydrogels have reuse capacity as both sensor and adsorbent material. Changing the amount of TACYC in the hydrogel structure changes the maximum adsorption capacity for Cu2+ ions. The Langmuir and Freundlich adsorption constants for Cu2+ ion adsorption of the hydrogels, acting as selective adsorbent in all aqueous media and metal ion mixtures, were determined.

In this study, p([2-(acryloyloxy)ethyl]trimethylammonium chloride-co-1-vinyl-2-pyrrolidinone) (p(AETAC-co-NVP) hydrogels containing positive charge in the structure were synthesized for the removal of anionic dyes from the aqueous media. The swelling behaviors affecting the adsorption properties of hydrogels structurally characterized by FTIR, SEM and EDX/mapping analysis were investigated. The effects of pH, dye concentration, adsorbent amount, dissolved anions and temperature on the adsorption of methyl orange (MO) and alizarin red S (AR) from aqueous media using p(AETAC-co-NVP) hydrogels were investigated. Using data obtained in adsorption studies, the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms and pseudo-first order (PFO), pseudo-second order (PSO), intra-particular diffusion, and Elovich kinetic model analyses were performed. The results showed that the p(AETAC-co-NVP) hydrogel was a good adsorbent for MO and AR anionic dyes and the adsorption process for both dyes complied with the Freundlich isotherm and PSO kinetic model. This situation indicates that the dominant mechanism for the adsorption of MO and AR dyes by the p(AETAC-co-NVP) hydrogel is strong electrostatic interactions and occurs as multilayered adsorption, not only on a planar region. Additionally, to the maximum adsorption values using p(AETAC-co-NVP) hydrogel for MO and AR dyes were reached at pH values of 7.0 and 5.0, respectively. According to all these findings, it can be said that the p(AETAC-co-NVP) hydrogel containing positivelly charged groups is a super adsorbent for adsorption of anionic dyes.

In this study, a new cationic monomer 2-(3-indol-yl)ethylmethacrylamide (IEMA) derived from tryptamine was synthesized in a single step and characterized by Fourier transform infrared (FTIR), H-1-NMR, and C-13-NMR. Then, one-step preparation of novel poly[2-hydroxyethylmethacrylate-c-2-(3-indol-yl)ethylmethacrylamide], or p(HEMA-c-IEMA), copolymeric hydrogels has been performed successfully with IEMA and 2-hydroxyethylmethacrylate (HEMA) as monomers using free radical aqueous polymerization. The hydrogels were characterized with scanning electron microscopy, FTIR, elemental analysis, thermogravimetric analysis, and texture profile analysis instruments. p(HEMA-c-IEMA) hydrogels were used for swelling, diffusion, drug release, and antibacterial activity studies. The drug-release behavior of the hydrogels was determined as a function of time at 37 degrees C in pH1.2 and 7.2. The swelling and drug-release studies showed that an increased IEMA amount caused a higher increase in swelling and drug-release values. Additionally, zero-order, first-order, and Higuchi equation kinetic models were applied to the drug-release data, and the data fit well in the Higuchi model, and the Peppas power-law model was applied to the release mechanism. Finally, the antibacterial activities of the hydrogels were screened against Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Salmonella typhimurium). (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45550.

In this study, Fe3+ ion selective N-(Rhodamine-6G)lactam-N'-acryloyl-ethylenediamine (RH6GAC) monomer was synthesized. Then, p(Acrylamide-co-N-(Rhodamine-6G)lactam-N'-acryloyl-ethylenediamine) (p(AAm-co-RH6GAC)) and p(2-hydroxyethyl- methacrylate-co- N-(Rhodamine-6G)lactam-N'-acryloyl-ethylenediamine) (p(HEMA-co-RH6GAC)) colorimetric hydrogels were synthesized by using acrylamide (AAm) and 2-hydroxyethylmethacrylate (HEMA) as primary monomers. FT-IR, SEM, polymerization yield and swelling characterizations were conducted for the resulting hydrogels. Then, these hydrogels were used in selective absorption of Fe3+ ions from aqueous media. The hydrogels, which could absorb Fe3+ ions selectively from a mixture of metal ions, were used as column packing material. The solutions containing Fe2+ and Fe3+ ions at different concentrations were separated at a rate of 97.7 ± 0.7%.

In this study, N-Allylsuccinamic acid was synthesized and characterized by FT-IR, 1H and 13C NMR analyses. Then, copolymeric hydrogels were synthesized by using N-Allylsuccinamic acid and acrylamide as monomers by using free radical polymerization. Once FT-IR, SEM and swelling characterizations of the obtained p(Acrylamide-co-N-Allylsuccinamic acid) hydrogels had been carried out, usability of the hydrogels in environmental applications as an effective absorbent material was shown. For this purpose, the absorption values were determined as 0.545 mmol g−1, 0.179 mmol g−1 and 0.051 mmol g−1 for the used hydrogels in the absorption of Cr3+, 4-Nitrophenol and basic fuchsin from aqueous media respectively.

Poly(acrylonitrile) (p(AN))-based materials such poly(acrylonitrile-co-(3-acrylamidopropyl)-trimethylammonium chloride (p(AN-co-APTMACl)), poly(acrylonitrile-co-4-viniyl pyridine) (p(AN-co-4-VP)) and poly(acrylonitrile-co-N-isopropylacrylamide) (p(AN-co-NIPAM)) core-shell nanoparticles were prepared. The core materials, AN, in p(AN-co-4-VP) nanoparticles, were amidoximated and the shell materials, 4-VP, were quaternized to generate p(AN-co-4-VP)(+) and p(AN-co-4-VP)(++), single and double positively charged core-shell nanoparticles, respectively. Furthermore, interpenetrating microgels-hydrogel (IPN) polymeric networks were prepared by mixing double quaternized p(AN-co-4-VP)(++) core-shell particles with acrylamide (AAm) and 2-hydroxyethylmethacrylate (HEMA) before polymerization. A model drug, fluorescein sodium salt (FSS) was used in absorption/release studies from these IPNs. Moreover, the prepared and chemically modified particles were tested against Staphylococcus aureus ATCC6538, Pseduomonas aeruginosa ATCC9027, Bacillus subtilis ATCC6633, and Escherichia coli ATCC8739, and found that some of these particles had antibacterial properties against tested bacteria.

4-vinyl pyridine (4-VP) based hydrogels with 2-hydroxyethylmetacrylate (HEMA) and magnetic composites were prepared and tested for use in the removal of UO 2 2 + and Th4+ ions from aqueous environments. It was found that the absorption of these metal ions from aqueous environments decreased with an increase in the amount of HEMA contained within p(4-VP-co-HEMA) hydrogels between 0.498 mmol for pure p(4-VP) and 0.027 mmol for pure p(HEMA). The characterization of the hydrogels was determined by swelling experiments, FT-IR and thermal analysis. The effects of initial metal ion concentration, hydrogel amount and the temperature of the medium on absorption of the ions were investigated. Langmuir and Freundlich isotherms were constructed for the absorption of UO 2 2 + and Th4+. Both isotherms demonstrated that these metal ions complied with monolayer absorption kinetics.

We report the preparation of metal nanoparticles in various formulations inside p(2-acrylamido-2-methyl-1-propansulfonic acid; p(AMPS)) hydrogels and their utilization as a catalyst in hydrolysis of NaBH4. The swollen, flexible p(AMPS) network was used for metal ion loading and reduction in situ for the preparation of Co:Ni nanoparticles as bimetallic clusters in various formulation, and Co and Ni bimetallic catalysts as Co + Co, Co + Ni, Ni + Co and Ni + Ni. In addition to utilization of hydrogels as support materials, the p(AMPS)-metal nanoparticle system was used as catalyst to generate hydrogen in the hydrolysis of NaBH4 with very high yield. Various parameters for the hydrolysis reaction were determined and the activation parameters were calculated. For the first time, inclusion of ferrite magnetic particles to control hydrogen generation on demand by using an externally applied magnetic field to remove the hydrogel-catalyst system from the hydrolysis medium is reported. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

In this study, hydrogels were synthesized from 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) via a photo polymerization technique. Approximately 100 nm Ni metal nanoparticles were generated in situ inside these p(AMPS) hydrogel networks and used as a catalyst in hydrogen production by hydrolysis of sodium boron hydride in a basic medium. The effects of several parameters on the hydrolysis reaction such as the amount of catalyst, the initial concentration of NaBH4, and the temperature were investigated. The activation energy, activation enthalpy and activation of entropy for the reaction were calculated as 42.28 kJ mol(-1), 39.59 kJ mol(-1) and -171.67 J mol(-1) K-1, respectively. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

Bulk poly(2-acrylamido-2-methyl-1-propansulfonic acid) (p(AMPS)) hydrogels were prepared by irradiation of an aqueous solution of AMPS in the presence of crosslinker and photoinitiator. These p(AMPS) hydrogel networks were utilized for in situ cobalt nanoparticle synthesis by reduction of metal ions absorbed into the hydrogel network with a reducing agent, i.e., NaBH(4). TEM images confirmed that Co particles are about 100 nm in size. The hydrogel network with embedded Co nanoparticles was utilized as a catalyst in the reduction of 4-nitrophenol (4-NP) and 2-nitrophenol (2-NP) in aqueous media in the presence of an excess amount of NaBH4. The kinetics of the reduction reaction under different reaction conditions was investigated to determine the activation parameters. Activation energies are 27.8 kJ mol(-1) and 39.3 kJ mol(-1) for 4-NP and 2-NP, respectively. It was found that hydrogel-Co composites were 99% active after 5 days storage. (C) 2010 Elsevier B.V. All rights reserved.

In this study, N-allylsuccinamic acid (NASA) was synthesized in a single step with a yield of 85%. Carboxylic acid containing NASA was characterized through Fourier transform infrared (FTIR) radiation and 1H-NMR and 13C-NMR analysis, and then it was used for synthesis of poly(2-hydroxylethyl methacrylate-co-N-allylsuccinamic acid) [p(HEMA-co-NASA)] hydrogels. The structure of the obtained pH-responsive p(HEMA-co-NASA) hydrogels were characterized with FTIR spectroscopy and scanning electron microscopy analysis, and their swelling characterization was carried out under different drug-release conditions. In the application step of the study, the hydrogels were used for the in vitro release of vitamin B12 and Rhodamine 6G, which were selected as model drugs. We determined that the hydrogels used as a drug-delivery matrix could release the drug they had absorbed under different release conditions (phosphate-buffered saline, 0.9% NaCl, and pH 1.2) at high rates for time periods of up to 24 h. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39660.

In this study, N-(Rhodamine-6G)lactam-N′-acryloyl-ethylenediamine (RH6GAC) as co-monomer was synthesized in two steps and characterized by FT-IR, 1 H, 13 C NMR and mass spectrometry. Metal ion (Na + , K + , Ca 2+ , Fe 2+ , Fe 3+ ,Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Pb 2+ , Cd 2+ , Hg 2+ , Mn 2+ , Ba 2+ , Mg 2+ ) selectivity of RH6GAC was investigated by UV–Vis and fluorescence spectrophotometry. Then, Fe 3+ ion selective and reusable naked-eye colorimetric copolymeric sensor hydrogels were synthesized using 2-hydroxyethylmethacrylate (HEMA) and acrylamide (AAm) as the primary monomer and N-(Rhodamine-6G)lactam-N′-acryloyl-ethylenediamine as comonomer by free radical polymerization. The sensor hydrogel was characterized by FT-IR and swelling properties.

Hydrogels based on p(4-VP) of different dimensions were prepared and, after chemical modification, were used in the removal of one of the most potent toxic materials, cyanide. Macro and micron p(4-VP) hydrogel swelling behavior was evaluated in various aquatic environments. HCl, bromoethane, 1-bromobutane, 1-bromohexane, and 2-bromoethylamine were used as quaternizing agents to generate positive charges on both p(4-VP) macrogels and microgels. The modified p(4-VP) macrogels and microgels were used in cyanide ion removal for the first time from aqueous environments. The p(4-VP)-HCl at macro and micro sizes removed almost 49 and 61 mg cyanide ions per gram hydrogel in deionized water after modification, respectively. Moreover, the absorption capacity of the modified p(4-VP) hydrogel did not change significantly in tap, drinking, and creek waters. Parameters that affect the absorption process, such as cyanide concentration, contact time, hydrogel amount, and contaminated water source, were investigated. Additionally, magnetic field responsive macro and micro p(4-VP) hydrogel composites provided many advantages, such as easy handling after cyanide absorption, e. g., ready removal of cyanide-loaded p(4-VP) composites with an externally applied magnetic field. Langmuir and Freundlich adsorption isotherms were applied to the data obtained for cyanide uptake from aqueous environments.

In this study, p(AMPS) hydrogels are synthesized from 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) via a photo polymerization technique. The hydrogels are used as template for metal nanoparticles and magnetic ferrite nanoparticles. and also as a catalysis vessel in the generation of hydrogen from the hydrolysis of NaBH4. Approximately 5 nm Ru (0) and 20-30 nm magnetic ferrite particles are generated in situ inside this p(AMPS) hydrogel network and then used as a catalysis medium in hydrogen production by hydrolysis of sodium boron hydride in a basic medium. With an applied external magnetic field, the hydrogel reactor, containing Ru and ferrite magnetic particles, can be removed from the catalysis medium; providing on-demand generation of hydrogen. The effect of various parameters such as the initial concentration of NaBH4. the amount of catalyst and temperature on the hydrolysis reaction is evaluated. The activation energy for hydrogen production by Ru (0) nanoparticles is found to be 27.5 kJ mol(-1); while the activation enthalpy is 30.4 kJ mol(-1). The hydrogen generation rate in presence of 5 wt% NaOH and 50 mg p(AMPS)-Ru catalyst is 8.2 L H-2 min(-1) g Ru. (C) 2011 Elsevier B.V. All rights reserved.

Macrogels and nanogels (5 x 6 mm and 370 nm dimensions, respectively) based on 4-vinylpyridine (p-(4VP)) were prepared using redox and microemulsion techniques. The p(4-VP)-based materials were quaternized with HCl/alkyhalides having different chain lengths to tune the charges (macro and nanogels) and size of nanogels. By developing positive charge on the p(4-VP) materials, they behaved as ion exchangers and used in removal of As(V) from aqueous environments. The prepared p(4-VP) materials were also rendered responsive to magnetic field by in situ incorporation of magnetic metal nanoparticles inside macro p(4-VP) hydrogels and by encapsulation of separately prepared magnetic ferrites by nanosized p(4-VP) particles. Nanoparticles quaternized with HCl (p(4-VP)-HCl) (1 g) removed over 95% of As(V) from a stock solution (10 mg L-1 1000 mL) in 15 min whereas bulk hydrogels removed >82% of the As(V) from an equivalent solution in similar to 12 h. Parameters effecting the As(V) removal, including pH, temperature and ionic strength, were also investigated. The synthesized magnetic p(4-VP) composites could be reused after elution with NaOH and regeneration with quaternization agents; these procedures were facilitated using an externally applied magnetic field. The Langmuir and Freundlich adsorption isotherms were also applied to study the removal of As(V) from aqueous environments. (C) 2011 Elsevier B.V. All rights reserved.

p(4-vinylpyridine) (p(4-VP)) hydrogels were prepared in bulk (macro, 5 x 6 mm) and in nanosizes (370 nm) dimensions. The prepared hydrogels were used to remove organic aromatic contaminates such as 4-nitrophenol (4-NP), 2-nitrophenol (2-NP), phenol (Ph) and nitrobenzene (NB) from an aqueous environment. Important parameters affecting the absorption phenomena, such as the initial concentration of the organic species and the absorbent, absorption rate, absorption capacity, pH and the temperature of the medium, were evaluated for both hydrogel sizes. The absorption capacity of bulk and microgels were found to be 4-NP > 2-NP > Ph > NB. Furthermore, p(4-VP) microgels were embedded in poly(acrylamide) (p(AAm)) bulk hydrogel as a microgel-hydrogel interpenetrating polymer network and proved to be very practical in overcoming the difficulty of using the microgels in real applications. Moreover, it was demonstrated that separately prepared magnetic ferrite particles inserted inside p(4-VP) microgels during synthesis allowed for trouble-free removal of p(4-VP)-magnetic composite microgels from the aqueous environment by an externally applied magnetic field upon completion of their task. (C) 2011 Elsevier Ltd. All rights reserved.

Polymeric hydrogels derived from 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) were utilized in the preparation of cobalt (Co) metal nanoparticles and used as a composite-catalyst system in hydrogen generation from the hydrolysis of NaBH(4). The embedded Co nanoparticles in the p(AMPS) networks are on the order of 100 nm. It was demonstrated that the p(AMPS)-Co composite system was very effective in the production of hydrogen from alkali aqueous sodium boron hydride solutions. The effect of various parameters such as the initial concentration of NaBH(4). the amount of catalyst and temperature on the hydrolysis reaction was evaluated. The activation energy for hydrogen production by Co particles was found to be 38.14 kJ mol(-1); while the activation enthalpy was 35.46 kJ mol(-1). (C) 2010 Elsevier B.V. All rights reserved.

Hydrogels with highly charged forms and amphiphilic character, based on an anionic monomer 2-acrylamido-2-methyl-1-propansulfonic acid sodium salt (AMPSNa) and a cationic monomer 3-acrylamidopropyltrimethylammoniumchloride (APTMACl), were synthesized via a photo-polymerization technique and investigated for potential use in the separation of chromium species with different oxidation states. They were used for three main purposes. First, a single chromium species was successfully removed from an aqueous medium in the presence of other forms using the appropriate design and synthesis of the hydrogels. Secondly, the copolymerized p(AMPSNa-co-APTMACl) hydrogels were used to remove two chromium species simultaneously from an aqueous medium. Lastly, in addition to speciation of the chromium species, their separation and removal by an externally applied magnetic field using magnetically responsive hydrogels was demonstrated.

We report the synthesis of poly(2-acrylamido-2-methyl-1-propansulfonic acid-co-vinylimidazole), p(AMPS-c-VI) hydrogels from various amounts of 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) and N-vinylimidazole (VI) monomers by photo-polymerization technique. Hydrogel composites with magnetic properties were synthesized in situ by incorporating Fe(II) and Fe(III) ions into p(AMPS-c-VI) hydrogels network and then reducing them with alkaline solution. Hydrogels swellings were performed for both bare and magnetic hydrogels. The selective removal capability of toxic metal ions, Cu(II), Cd(II), Fe(II), and Pb(II) by these hydrogels was studied in aqueous medium. Desorption studies were also performed in weakly acidic media to observe whether these hydrogel composites can be utilized as reusable tool for the toxic metal ion removal. The effects of the gel amount, contact time with metal ions, metal species and metal ion concentrations on absorption phenomena were evaluated. The equilibrium removal process of metal ions by the composite hydrogels complies well with the Langmuir adsorption isotherm model. (C) 2010 Elsevier B.V. All rights reserved.

Nickel nanoparticles inside poly(2-acrylamido-2-methyl-1-propansulfonic acid) (p(AMPS)) hydrogel were prepared by reduction of Ni(II) ions absorbed within hydrogel network. TEM images confirmed that in situ formed nickel particle in p(AMPS) hydrogel networks are about 100 nm. These nickel metal nanoparticles containing hydrogel-composites were utilized as catalysts and reaction media for the reduction reactions of aromatic nitro compounds, 2- and 4-nitrophenols with aqueous NaBH(4). The reduction rate constants at four different temperatures (30, 40,50 and 60 degrees C) and activation parameters were calculated. The activation energies (E(a)) for 4- and 2-nitrophenols are 25.70 and 38.69 kJ mol(-1), respectively. It was found that these types of hydrogel-composite catalyst systems can be used repetitively up to five times with 100% conversion and only with 25% reduction in the initial reduction rate. (c) 2010 Elsevier B.V. All rights reserved.

Hydrogels, based on 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) were synthesized via photopolymerization technique and used for the preparation of magnetic responsive composite hydrogels. These composite hydrogels with magnetic properties were further utilized for the removal of toxic metal ions such as Cd(II), Co(II), Fe(II), Pb(II), Ni(II), Cu(II) and Cr(III) from aqueous environments. It was revealed that hydrogel networks with magnetic properties can effectively be utilized in the removal of pollutants. The results verified that magnetic iron particle containing p(AMPS) hydrogel networks provide advantageous over conventional techniques. Langmuir and Freundlich adsorption isotherms were applied for toxic metal removal and both isotherms were fit reasonably well for the metal ion absorptions. (c) 2009 Elsevier Ltd. All rights reserved.