Zinc adsorption in Argisol from Paraíba State, Brazil: effect of pH

Abstract

Reactions of heavy metals with the soil are important in determining metal fate in the environment. The pH influences the adsorption of cations due to the variation of the electric charge. This study was carried out to investigate how varying soil solution pH affects the zinc adsorption in Argisol samples from Paraíba State, Brazil. Adsorption isotherms were elaborated from batch adsorption experiments, with increasing Zn concentration (1 - 90 mg L-1) and with 4 and 6 pH values. Isotherms were H and L-type and experimental results were fitted to nonlinear Langmuir model. Maximum adsorption ranged from 0.1103 – 0.7491 mg g-1 (pH 4) and from 0.3823 – 0.7885 mg g-1 (pH 6). Soils PVAe and PVe (1) had greater capacity for adsorption of Zn. Zinc adsorption increased with the elevation of the pH, although the bonding energy, in some soils, had decreased.