Cr(VI) removal from aqueous solutions using aluminosilicate minerals in their Pb- exchanged forms

A.G.Thanos, E. Katsou, S. Malamis, V. Drakopoulos, P. Paschalakis, E.A. Pavlatou, K. J. Haralambous

Applied Clay Science (2017), 147, 54-62

This work investigated the removal of Cr(VI) from aqueous solutions by employing Pb-modified zeolite, vermiculite and perlite as adsorbents. Natural zeolite and vermiculite exhibited high Pb2+ adsorption (~80% of the total Pb2+ concentration in solution), while perlite resulted in low lead adsorption (21%). Subsequently, the Pb-modified zeolite and vermiculite exhibited high Cr(VI) adsorption. The maximum Cr(VI) adsorption capacity as predicted by the Langmuir isotherm was 18.9 mgg−1 for zeolite and 23.0 mgg−1 for vermiculite. Langmuir was the isotherm equation that best fitted the experimental data. In terms of kinetics the Elovich equation represented the best fit to Cr(VI) adsorption on the studied modified minerals. The lowest mineral concentration that was tested (10 gL−1) resulted in the highest solid phase equilibrium concentration. Desorption experiments were not effective since the desorption percent achieved with NaCl solution was very low (4–6%). Cr(VI) removal using Pb-modified minerals can be applied in the successive treatment of industrial wastewater first for lead and then for Cr(VI) removal.

doi: 10.1016/j.clay.2017.05.040

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