Sorption and Release of Cadmium in Some Sewage Irrigated Soils

Studies on sorption of cadmium were carried out in some sewage irrigated soils. The data followed Langmuir and Freundlich adsorption isotherms. The value of adsorption maxima b was significantly higher if soils of high pH, organic matter, calcium carbonate, cation exchange capacity and clay content. The bonding energy constant K, however, was dependent only on the CaCO₃ and total iron content of soils. The constants of Freundlich isotherms followed the same trend as those of Langmuir constants. Release of adsorbed Cd by 1N neutral ammonium acetate decreased with increase in pH, organic matter, CaCO₃, cation exchange capacity and clay. Soils with high bonding energy constant and adsorption maxima released lesser amount of cadmium.