The adsorption behaviors of montmorillonite and some other clay minerals for cadmium

An experimental study of the adsorption of clay minerals such as montmorillonite,illite,kaolinite and sepiolite for Cd2+ was conducted. The results indicate that acidity and ion intensity are factors affecting adsorption,that the adsorption reaction is rapid,and that adsorption kinetics is fitted well with the Lagergren quasi-second reaction rate model. Under the optional conditions,the adsorption of kaolinite for cadmium is weak,and the saturated adsorption capacities of montmorillonite,illite and sepiolite for cadmium are 2.88,1.08 and 2.82 mg/g respectively. The behaviors of adsorption of Cd2+ on montmorillonite are fitted to Freundlich Model,while the behaviors of adsorption of Cd2+ on illite and sepiolite are fitted to Langmuir Model. Correlation analysis shows that the saturated adsorption capacity of cadmium on silicate clay minerals is related to its physical and chemical properties,and the correlation between manganese oxides and the saturated adsorption capacity of cadmium is extremely significant.