Dursun Saraydin

Swelling equilibria and dye adsorption studies of chemically crosslinked superabsorbent acrylamide/maleic acid hydrogels

Abstract Superswelling acrylamide (AAm)/maleic acid (MA) hydrogels were prepared by free radical polymerization in aqueous solution of AAm with MA as comonomer with some multifunctional crosslinkers such as trimethylolpropane triacrylate and 1,4-butanediol dimethacrylate. AAm/MA hydrogels were used in experiments on swelling and adsorption of a water-soluble monovalent cationic dye such as Basic Blue 17 (Toluidin Blue). As a result of dynamic swelling tests, the influence of relative content of MA on the swelling properties of the hydrogel systems was examined. AAm/MA hydrogels were swollen in the range 1660–6050% in water, while AAm hydrogels swelled in the range 780–1360%. Equilibrium water content of AAm/MA hydrogels were calculated in the range 0.8873–0.9837. Water intake of hydrogels followed a non-Fickian type diffusion. The uptake of the cationic dye, BB-17 to AAm/MA hydrogels is studied by batch adsorption technique at 25 °C. In the experiments of the adsorption equilibrium, S-type adsorption in Giless classification system was found. The binding ratio of hydrogel/dye systems was gradually increased with the increase of MA content in the AAm/MA hydrogels.

A review on the radiation synthesis of copolymeric hydrogels for adsorption and separation purposes

Recent theoretical and experimental work on the radiation synthesis, characterization and the use of hydrogels containing diprotic acid moieties have been reviewed. It is shown that upon incorporating vinyl monomers carrying diprotic acid groups randomly in the main chain, non-ionic hydrogels like poly(acryl amide) and poly(n-vinyl 2-pyrrolidone) acquired stimuli-responsive behaviours. The swelling behaviours of these hydrogels are shown to be predictable reliably under varying solution conditions by a theoretical expression derived recently. Examples are given for the utilization of these hydrogels in the adsorption and separation of biomolecules, dyes and metal ions in aqueous media and their ability to release drugs in stepwise manner in response to pH of the environment.

In vitro swelling studies and preliminary biocompatibility evaluation of acrylamide-based hydrogels

In this in vitro study, the biocompatibility of acrylamide-based hydrogels such as acrylamide/crotonic and acrylamide/itaconic acid, prepared by using gamma-rays, has been investigated against some biochemical parameters of human serum. The swelling kinetics of acrylamide/crotonic and acrylamide/itaconic acid hydrogels are investigated in distilled water and physiological saline solution and some swelling and diffusion parameters have been calculated. For the analysis of biocompatibility, acrylamide/crotonic and acrylamide/itaconic acid hydrogels are incubated in 10 different human sera for 24 h and their biocompatibilities with some biochemical parameters have been investigated. No significant difference in values before and after the test procedures have been found. It is therefore concluded that acrylamide/crotonic and acrylamide/itaconic acid hydrogels are biocompatible.

Behaviors of acrylamide/itaconic acid hydrogels in uptake of uranyl ions from aqueous solutions

Abstract In this study, adsorptions of uranyl ions from two different aqueous uranyl solutions by acrylamide-itaconic acid hydrogels were investigated by a spectroscopic method. The hydrogels were prepared by irradiating with γ-radiation. In the experiment of uranyl ions adsorption, Type II adsorption was found. One gram of acrylamide-itaconic acid hydrogels sorbed 178–219 mg uranyl ions from the solutions of uranyl acetate, 42–76 mg uranyl ions from the aqueous solutions of uranyl nitrate, while acrylamide hydrogel did not sorb any uranyl ion. For the hydrogel containing 40 mg of itaconic acid and irradiated to 3.73 kGy, swelling of the hydrogels was observed in water (1660%), in the aqueous solution of uranyl acetate (730%), and in the aqueous solution of uranyl nitrate (580%). Diffusions of water onto hydrogels were a non-Fickian type of diffusion, whereas diffusions of uranyl ions were a Fickian type of diffusion.

Adsorptions of Some Heavy Metal Ions in Aqueous Solutions by Acrylamide/Maleic Acid Hydrogels

Abstract In this study, acrylamide—maleic acid (AAm/MA) hydrogels in the form of rod have been prepared by γ-radiation. They have been used for adsorption of some heavy metal ions such as uranium, iron, and copper. For the hydrogel containing 40 mg of maleic acid and irradiated at 3.73 kGy, maximum and minimum swellings in the aqueous solutions of the heavy metal ions have been observed with water (1480%) and the aqueous solution of iron(III) nitrate (410%), respectively. Diffusions of water and heavy metal ions onto hydrogels have been found to be of the non-Fickian type of diffusion. In experiments of uranyl ions adsorption, Type II adsorption has been found. One gram of AAm/MA hydrogels sorbed 14–86 mg uranyl ions from solutions of uranyl acetate, 14–90 mg uranyl ions from solutions of uranyl nitrate, 16–39 mg iron ions from solutions of iron(IV) nitrate, and 28–81 mg copper ions from solutions of copper acetate, while acrylamide hydrogel did not sorb any heavy metals ions.

Radiation Induced Superabsorbent Hydrogels. Acrylamide/Itaconic Acid Copolymers

Acrylamide/itaconic acid hydrogels in the form of rods are prepared by γ-irradiation of ternary mixtures of acrylamide/itaconic acid/water with 2.00–5.71 kGy γ-rays. Spectroscopic and thermal characterization of the copolymers were examined. Dynamic and equilibrium swelling behavior of superabsorbent acrylamide/itaconic acid hydrogels was investigated in water. The equilibrium swelling degree, the swelling rate coefficient, the diffusion constant, the diffusion exponent, the diffusion coefficient, and the intrinsic diffusion coefficient of acrylamide/itaconic acid hydrogels were calculated. The superabsorbent hydrogels have shown mass swelling capabilities in the range 650–700% (for polyacrylamide hydrogels) and 900–2100% (for acrylamide-itaconic acid hydrogels). Diffusion type of the hydrogels is non-Fickian diffusion. The equilibrium swelling studies were used to determine important parameters of the crosslinked structure of the hydrogels, including the average molar mass between crosslinks and crosslink density.

Adsorption of bovine serum albumin onto acrylamid—maleic acid hydrogels

In this study, acrylamide-maleic acid hydrogels containing different amounts of maleic acid have been prepared by irradiating with gamma radiation. They have been used in experiments on bovine serum albumin (BSA) adsorption. Acrylamide-maleic acid hydrogel containing 60 mg of maleic acid and irradiated at 5.20 kGy has been used for swelling and diffusion studies in water, solutions of NaCl and BSA. For this hydrogel, maximum and minimum swellings have been observed with water (1680%) and the solution of BSA (1085%), respectively. Diffusions of water, NaCl and BSA within hydrogels have been found as non-Fickian types of diffusion. In the experiments of BSA adsorption, Langmuir type adsorption has been found. The hydrogel prepared with 60 mg maleic acid and having been irradiated at 2.00 kGy has been found to be the best adsorption system for BSA. The adsorption capacity of acrylamide hydrogel has been increased by the addition of maleic acid almost 1.5-3-fold.

Interaction of some cationic dyes with acrylamide/itaconic acid hydrogels

SYNOPSIS Acrylamide/itaconic acid (AAm/IA) hydrogels prepared by irradiating with y radiation were used in experiments on uptake of some cationic dyes such as union green B (UG-B), basic blue 17 (BB-17), basic red 2 (BR-2), and lauths violet (LV). Adsorption of the cationic dyes onto AAm/IA hydrogels is studied by batch adsorption technique at 25°C. In the experiments of the adsorption, Langmiur type adsorption in the Giles classification system was found. Some binding and thermodynamic parameters for AAm/IA hydrogel-dye systems were calculated by using Klotz method. Adsorption studies indicated that monolayer coverages of AAm/IA hydrogel by these dyes were increased with following order BB-17 > UGB > BR-2 > LV. 0 1996 John Wiley & Sons, Inc.

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.

Synthesis, characterization and evaluation of IPN hydrogels for antibiotic release.

We prepared new ternary interpenetrating polymeric networks (IPN) systems containing chitosan, poly(N-vinylpyrrolidone) and poly(acrylamide) polymers. IPNs were synthesized by radical polymerization of acrylamide monomers in presence of glutaraldehyde (G) and N,N′-methylenebisacrylamide as crosslinkers and the other polymers. These IPNs were named as C-P-A. Glutaraldehyde were used in different concentration to control the network porous of IPNs. Spectroscopic and thermal analyses of these cylindrical shaped IPNs were made with fourier transform infrared spectroscopy analysis, thermogravimetric analysis, and thermomechanical analysis. Swelling studies of IPNs were carried out at pH 1.1 and pH 7.4 at 37°C. The swelling and diffusion parameters of IPNs in these solutions were calculated. Amoxicillin as a bioactive species was entrapped to the IPNs during synthesis. In vitro release kinetics of IPNs were investigated. The experimental data of swelling and release studies suggest clearly that the swelling and release process obeys second-order kinetics. The release of the entrapped bioactive species from IPNs depends on the degree of crosslinking of the polymer and pH of the medium at body temperature. We observed that amoxicillin release at pH 1.1 was higher than at pH 7.4. As a result, IPNs-based chitosan with different cross-linker concentration could be promising candidates for formulation in oral gastrointestinal delivery systems.