Radiation polymerization and concentration separation of P(NIPA-co-AMPS) hydrogels

Extraction or concentration with temperature-sensitive hydrogels is a novel separation technology. In this study, N-isopropylacrylamide (NIPA) was synthesized by acrylonitrile and isopropanol. Poly(N-isopropylacrylamide) (PNIPA) and copolymer of NIPA and 2-acrylamide-2-methylpropane sulfonate [P(NIPA-co-AMPS)] hydrogels were prepared by radiation polymerization. Dependence of their swelling behavior on temperature was studied. Effects of radiation dose on polymerization, feed composition on thermoresponse, electrolyte on relative swelling ratio, and swelling and deswelling kinetics were investigated. The experimental results showed that P(NIPA-co-AMPS) hydrogels with low content of AMPS/NIPA (1-5%), prepared at a radiation dose-rate of 1 kGy/h and total dose of 30-40 kGy, could enhance the swelling ratio of PNIPA hydrogels significantly and raise the phase-transition temperatures. P(NIPA-co-AMPS) hydrogels produced under optimum conditions were used to concentrate aqueous bovine serum albumin (BSA, M = 69 000 g mol(-1)) solution. When aqueous BSA concentration was below 5%, the separation efficiency was more than 80% with low cost and low energy consumption. (C) 2005 Society of Chemical Industry.