SORPTION OF COMPETING HEAVY METALS ON LATERITE

Abstract

Heavy metal pollution is a major concern for environmentalists. Competing ions affect the sorption of heavy metals onto the surfaces of soils. This study evaluated competitive adsorption of Cd, Cr, Pb, Cu and Zn from two laterite samples – Emuhu Laterite, LAEM and Abeokuta Laterite, LAAB, obtained from Nigeria. The equilibrium concentrations of heavy metals following adsorption using mixed metal solutions were determined. Laterite affinities for heavy metal adsorption were determined by means of selectivity sequences. The adsorption sequences obtained were Cu > Pb > Cr > Zn > Cd and Cu > Cr > Pb ≫ Zn > Cd for LAEM and LAAB, respectively. Cr, Pb, Cu were strongly adsorbed by both soils. Adsorptions of the heavy metals on LAEM and LAAB fitted into the Freundlich and Langmuir isotherm model, respectively. The results suggested that Emuhu Laterite, LAEM and Abeokuta Laterite, LAAB, can receive and hold Cr, Pb and Cu pollutants in solution. They can thus be recommended for remediation of the three metals from industrial waste effluents.