Removal of chromium complex dye from aqueous solutions using strongly basic and weakly basic anion exchangers

Removal of chromium complex dye from aqueous solutions by sorption onto a weakly basic, acrylic matrix anion exchanger Purolite A845 and a strongly basic, polystyrene matrix anion exchanger Purolite A 500P has been investigated under various experimental conditions: the initial dye concentration, pH and temperature. The sorption of chromium complex dye proceeds as a result of miscellaneous interactions between the dye and anion exchanger: ion exchange and physical sorption. The removal efficiency of chromium complex dye was found to be somewhat higher using Purolite A 845 than that using Purolite A 500P in both acidic and neutral solutions. The experimental data are in good agreement with the Langmuir isotherm and the pseudo-second order rate models. The performance of Purolite A 845 in chromium complex dye removal was verified in column experiment. The working capacity was 17,26 mg per gram of dry anion exchanger at the c0 = 83,4 mg/L and pH 2. The maximum concentration of dye in eluate was obtained using a 2-3 bed volume mixture (1:1) of 5% NaOH – ethanol.