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Sulfur containing poly(N-isopropylacrylamide) copolymer hydrogels for thermosensitive extraction of gold(III) ions



Poly[N-isopropylacrylamide-co-[2-(methylthio)ethyl methacrylate]], poly(NIPA-co-MTEMA) gels were prepared by free radical polymerization in aqueous solution. The homogeneous and heterogeneous gels were prepared by using 10 mM MTEMA in 5.0%(v/v) ethanol at 10°C and 30 mM MTEMA in 20%(v/v) ethanol at 50°C, in 1.0 and 1.5M NIPA solution, respectively. Homogeneous and heterogeneous gels had swelling ratios at 540 ± 28% and 551 ± 37%, respectively. The extraction of Au(III) ion was studied in batch method. The optimum pHs for the extraction of Au(III) by homogeneous and heterogeneous gels were 1–3 and 1–5, respectively. The suitable extraction time was 3 h at 50°C when using a rod-shaped copolymer (0.7 cm diameter and 1 cm length). The adsorption behavior obeyed the Langmuir and Freundlich isotherms. The maximum sorption capacities of Au(III) onto homogeneous and heterogeneous gels were 62.8 and 322 μmol/g, respectively. The desorption equilibrium was reached within 2–3 h at 10°C by 0.1M thiourea in 5%(v/v) HCl. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011