Erdener Karadağ

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.

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.

Immobilization of Saccharomyces cerevisiae on to acrylamide–sodium acrylate hydrogels for production of ethyl alcohol

Abstract Acrylamide/sodium acrylate (AAm/SA) copolymers, prepared by using various crosslinkers, were used in experiments on swelling, diffusion, immobilization of yeast cells (Saccharomyces cerevisiae) and production of ethyl alcohol. AAm/SA hydrogels were used for swelling and diffusion studies in the nutrient medium of the cells. The parameters of equilibrium swelling, maximum swelling, initial swelling rate, diffusional exponent, network constant and diffusion coefficient of the hydrogel/penetrant systems were calculated and evaluated. Yeast cells were immobilized onto the hydrogels by adsorption method during multiplication and ethyl alcohol production of the hydrogels was investigated. Swelling of AAm increased with the addition of SA and ethyl alcohol production increased with increasing SA in the hydrogels. The best system for immobilization is found to be AAm/SA hydrogels containing N,N′-methylenebisacrylamide as crosslinker.

Adsorption of Some Basic Dyes by Acrylamide-Maleic Acid Hydrogels

Abstract In this study, acrylamide-maleic acid (AAm/MA) hydrogels containing different quantities of maleic acid have been irradiated with γ-radiation. They have been used in experiments on swelling, diffusion, and the adsorption of basic dyes such as methylene blue, methyl violet, and nile blue. Acrylamide-maleic acid hydrogel containing 40 mg maleic acid and irradiated at 3.73 kGy has been used for swelling and diffusion studies in water and solutions of basic dyes. For this hydrogel, maximum and minimum swellings have been observed with solutions of nile blue (2000% swelling) and water (1480% swelling). Diffusions of water and dyes within hydrogels have been found to be non-Fickian in character. In experiments on the adsorption of dyes, Type III adsorption has been found. One gram of AAm/MA hydrogel sorbed 0.3–2.2 mg of methylene blue, 0.3–3.4 mg of methyl violet, and 1.6–3.9 mg of nile blue, while acrylamide hydrogel has not sorbed any basic dye. This result shows that AAm/MA hydrogel can be used as a...

Water Sorption and Dye Uptake Studies of Highly Swollen AAm/AMPS Hydrogels and Semi-IPNs with PEG

A semi-interpenetrating network (semi-IPNs) hydrogel, composed of acrylamide (AAm) with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) as co-monomer, with poly(ethylene glycol) (PEG) and two multifunctional cross-linkers such as 1,4-butanediol dimethacrylate (BDMA), and trimethylolpropane triacrylate (TMPTA) was prepared. AAm/AMPS hydrogels and AAm/AMPS/PEG semi-IPNs were synthesized by free radical solution polymerization. Swelling experiments were performed in water at 25°C, gravimetrically. For sorption of Toluidin Blue (Basic Blue 17, TB) into AAm/AMPS hydrogels and AAm/AMPS/PEG semi-IPNs was studied by batch sorption technique at 25°C. Dye removal capacity, removal effiency and partition coefficient of the hydrogels was investigated.

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.