ZINC ADSORPTION BY A LATERITIC SOIL IN THE PRESENCE OF ORGANIC-LIGANDS

Zinc adsorption by a lateritic podzolic soil was measured in the presence of acetate, oxalate, citrate, tricarballylate, salicylate, catechol, or humate. Zinc remaining in solution was measured by atomic absorption spectrometry. Zinc adsorption and pH decreased in the presence of each of the ligands except catechol. Seventy-four percent of the variation in adsorption was accounted for by the combined effects of the concentration of zinc-ligand complex (Zn-L) and the concentration of ZnOH+ that were present in solution after adsorption. However, other factors such as changes in the number of sites available for adsorption, the point of zero salt effect of the soil, and the charge of zinc species also contributed to the magnitude of zinc adsorption. -from Authors