Sorption profile of cadmium ions onto styrene-divinylbenzene copolymer beads

摘要

The sorption behavior of cadmium ions from aqueous media was investigated on styrene-divinylbenzene copolymer beads (St-DVB) as an adsorbent. Various physicochemical parameters were optimized to simulate the best conditions which can be used to decontaminate cadmium ions from aqueous media using St-DVB beads as an adsorbent. Maximum adsorption was observed at 0.001 mol L-1 acid solutions (HNO3, HCl, H2SO4 and HClO4) using 0.2 g of adsorbent for 8.89 x 10(-5) mol L-1 of cadmium ions within three minutes equilibration time. The adsorption data followed the Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms over the cadmium concentration range of 8.89 x 10(-4) to 8.01 X 10(-3) molL(-1). The characteristic Freundlich constants, i.e. 1 = 0.243 +/- 0.007 and A = 1.783 x 10(-3) +/- 2.069 x 10(-5) mol g(-1) have been computed for the sorption system. Langmuir isotherm gave a saturated capacity of 0.334 +/- 0.0123 mmol g(-1). The sorption mean free energy from D-R isotherm was found to be 16.31 +/- 0.31 kJ mol(-1) indicating chemisorption involving chemical bonding for the adsorption process. The uptake of cadmium increased with the rise in temperature. Thermodynamic parameters, i.e. Delta G, Delta H and Delta S have also been calculated for the system. The sorption process was found to be endothermic. The proposed procedure was applied to remove cadmium from tap water and industrial effluent.