Selective removal of Cr(III) from aqueous solution using cross-linked polyethylenimine: experimental optimization and modeling

Abstract

Batch removal of Cr(III) from aqueous solutions using cross-linked polyethylenimine was investigated under different experimental conditions. The influence of different parameters on the adsorption behavior, including adsorbent dosage (0.02–1.5 g), solution pH (at 3 and 8), initial concentration (10–60 mg L−1), competing ions (U, Pb, As, Se, Hg and Mn) and contact time (10–120 min), has been studied. The selectivity of cross-linked polyethylenimine toward Cr(III) as well as its ability to be regenerated for reuse has been assessed. The modified polymer exhibited high selectivity toward Cr(III) with high removal efficiency of up to 89% in acidic solution and 99% in basic solution and showed similar performance when applied to wastewater samples. The polymer exhibited good potential for reuse, giving good removal efficiency (> 50%) up to three cycles. Langmuir isotherm was found to better describe the equilibrium adsorption data, while adsorption kinetic was conformed to the Pseudo second-order. The thermodynamic modeling indicates that the adsorption occurs via chemisorption.