ZINC ADSORPTION BY TWO ALKALINE SOLIDS

Publisher Website
Google Scholar
Abstract
Zn adsorption by 2 alkaline soils, Mormon clay loam and Willows clay, both deficient in Zn for rice culture, was examined over a wide range of Zn solution concentrations. At Zn equilibrium concentrations (0.1 ppm Zn for Willows clay and 0.23 ppm for Mormon clay loam), Zn adsorption at 25.degree. C can be described by either the Langmuir or the Freundlich adsorption isotherm. The exponent of concentration of the Freundlich equation is about 1.0. At higher Zn concentrations, Zn adsorption can be described only by the Freundlich equation, with the exponent of concentration being 0.31. Zn adsorption by Mormon clay loam and Willows clay is an endothermic reaction. The rate of Zn adsorption can be described by a multiple-order kinetic equation. The activation energy of adsorption is 43.1 kCal per mole for Mormon clay loam and 31.4 kCal per mole for Willows clay. Because of the high activation energy, the adsorption is considered to be chemisorption rather than due to the electrostatic attraction forces between Zn ions and the surfaces of colloidal particles. The greater stability of adsorbed Zn may result from dehydration during the aging of Zn absorbed on the surface of clay minerals.
Keywords

This publication has 2 references indexed in Scilit: