Adsorption Isotherms of Cobalt in Soils of Varying Properties

In a study on adsorption isotherms of cobalt on soils of Entisols of Ambala, Inceptisols of Jind (Haryana) and Ultisols of Palampur (Himachal Pradesh), Langmuir and Temkin equations were tested to describe the specific and non-specific adsorption of cobalt. Temkin equation gave a better fit only in Ambala soil while Langmuir equation gave a better fit of specific adsorption of cobalt in Palampur and Ambala soils. When increasing amounts of cobalt were added to the soil suspensions, equilibrium cobalt concentration of soil solution increased, showing thereby the increased intensity factor of cobalt supply. The regression equations to give the amount of sorbed cobalt at a known equilibrium cobalt concentration are x/m=0.336+2.813C, x/m=0.277+2.156C and x/m=0.262+2.754C for Palampur, Ambala and Jind soils, respectively. The differences in adsorption capacity of cobalt were attributed to clay content and mineralogical composition of these soils. Adsorption maximum and bonding term were also worked out.