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

Abstract

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.