Competitive Sorption of Metallic Species under Different pH in a Residual Clayey Soil

Abstract

Soil contamination by toxic metals is a major environmental issue, mainly due to inadequate methods of waste disposal and accidental spills. Studies on fate and transport of contaminants help prevent the spread of pollutants in subsurface soil and mitigate associated risks. Therefore, the objective of this study is to evaluate the sorption mechanisms involving seven metallic species (nickel, cadmium, lead, chromium, zinc, copper, and manganese) in a residual clayey soil, when available individually (single-species solution) or combined (multispecies solution), under different pH values in the acidic range. Batch equilibrium tests were conducted, from which sorption isotherms and partition coefficients—Kd were determined and evaluated. The results showed that, for the clayey soil investigated, the pH of the contaminant solution significantly influenced Kd. For Cr, Pb, and Cu, higher retention capacities were observed for both single and multicomponent species solutions, while Zi, Ni, Cd, and Mn showed greater mobility.