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Solutions, obtained from the mixture of different mole ratios of N-vinyl 2-pyrrolidone and acrylonitrile, were irradiated in a 60 Co-γ source to produce copolymers. The swelling percentage curves were formed, and a diffusion exponent was calculated. For the uranyl ion adsorption, these copolymers were reacted with hydroxylamine hydrochloride to convert C≡N groups to -C=N-OH (amidoxime) groups. The optimum amidoximation time was determined by uranyl ion adsorption. The structure of copolymers, before and after amidoximation, was analyzed with spectroscopic and thermal methods.

Removal of nitrite ions from aqueous solutions by protonated poly(N,N-dimethylamino ethylmethacrylate) hydrogels (P(DMAEMA)) was investigated. We have shown that polycationic and pendant secondary amine group containing P(DMAEMA) hydogels is very efficient and highly selective for the removal of nitrite ions from aqueous solutions at even in very high concentrations. Adsorption studies have shown that pH of the nitrite solution has influence on the nitrite ion uptake capacity of P(DMAEMA) hydrogels.The adsorption capacity of hydrogels had been increased up to 3100 mg NO À1 2 /g dry gel, by changing pH of the solution. The results of the adsorption studies showed that the interaction between nitrite ions and quaternized amine groups agree with the Langmuir-type isotherm.

Acrylamide–maleic acid (AAm–MA) hydrogels were prepared by gamma‐irradiation of their aqueous solutions. UO2+2 ion uptake on P(AAm–MA) hydrogels was investigated using two types of gel systems prepared by a simple irradiation method and a prestructured reaction. It has been observed that gels prestructured with UO2+2 ions adsorbed approximately 15–20% more UO2+2 ions than gels prepared in pure water (the usual method). It was also found that the uranyl ion adsorption capacity of hydrogels increased with an increasing amount of maleic acid in the gel system and an increasing concentration of uranyl ion in the solution. A possible interaction mechanism between the groups in the copolymeric gels and UO2+2 ion has been proposed based on the stoichiometry and the spectroscopic evidence. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 284–289, 2000

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