Zinc adsorption by goethite in the absence and presence of phosphate

Abstract

Zinc adsorption by goethite in the presence of 0.1M sodium chloride was found to occur at pH values well below the isoelectric point of the goethite when the surface was positive and the zinc in a cationic form. This confirms data already presented by Forbes et al. (1976). The presence of phosphate or zinc on the goethite surface was found to increase slightly the adsorption of zinc and phosphate respectively. Depending on the pH value, the total adsorption could be larger than for either ion in the absence of the other and the capacity of the surface for each of the ions. As suggested by Stanton and Burger, a surface complex may be formed.