The study of various parameters affecting the ion exchange of Cu 2+, Zn 2+, Ni 2+, Cd 2+, and Pb 2+ from aqueous solution on Dowex 50W synthetic resin

Abstract

A gel resin containing sulfonate groups (Dowex 50W) was investigated for its sorption properties towards copper, zinc, nickel, cadmium and lead metal ions. The use of selective ion exchange to recover metals from aqueous solution has been studied. The ion exchange behavior of five metals on Dowex 50W, depending on pH, temperature, and contact time and adsorbate amount was studied. Experimental measurements have been made on the batch sorption of toxic metals from aqueous solutions using cation exchanger Dowex 50W. The maximum recoveries (about 97%) Cu 2+, Zn 2+, Ni 2+, Cd 2+ and (about 80%) Pb 2+ were found at pH ranges 8–9. The amount of sorbed metal ion was calculated as 4.1, 4.6, 4.7, 4.8, and 4.7 mequiv./gram dry resin for Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+, respectively. The precision of the method was examined at under optimum conditions. Selectivity increased in the series: Pb > Cd > Cu > Zn > Ni. It has been observed that, selectivity of the –SO 3H group of the resin increases with atomic number, valance, degree of ionization of the exchanged metals. The equilibrium ion exchange capacity of resin for metal ions was measured and explored by using Freundlich and Langmuir isotherms. Langmuir type sorption isotherm was suitable for equilibrium studies.