Studies on Adsorption of Manganese

Adsorption of Mn was studied on eight soils varying Widely in physical and chemical characteristics by using two approaches, viz. Langmuir adsorption isotherm and exchange equation. Data on Mn adsorption conformed to the linear form of Langmuir equation in original soils while in Ca-saturated soils, Ca-Mn exchange equation proved a better parameter for Mn adsorption. Selectivity coefficient (K_Ca^Mn) was found to decrease logarithmically in Ca-saturated soils, indicating more than one type of adsorption sites. Mn adsorption was also accompanied by the drop in soil pH. In the light of release of protons, different mechanisms of Mn adsorption have been elucidated. Soils dominated by kaolinite exhibited specific adsorption.