HEAVY METAL DESORPTION STUDIES ON THE ARTIFICIALLY CONTAMINATED AL-QATIF SOIL

Abstract

In this study, the relevance of mineralogy on the desorption capacities of Cu+2 and Pb+2 from
artificially contaminated Al-Qatif soil has been investigated. The desorption capacities of both Cu+2 and Pb+2
using ethylenediaminetetraacetate (EDTA) as decontaminating solution are determined. The effect of
decontaminating solution dosage and liquid to solid ratio on desorption capacities are examined. Under
identical conditions, the removal efficiency of Pb+2 ions are found to higher than Cu+2 ions. This has been
attributed mainly due to the differences in surface charges of specific retention sites which hold these metal
ions. Further, the heavy metal ion solubility and surface properties of respective clay minerals decide the
desorption rate in soil systems as the pore fluid pH reaches the heavy metal solubility range or point of zero
charge of the clay minerals. These studies provide valuable insight with regards to their applicability as
potential barrier materials for containing industrial leachates.