Adsorption of Sr2+ by bentonite and alkaline fusion activated bentonite

Abstract:

Using bentonite as the main raw material, zeolite A was prepared by alkaline melting. The static adsorption experiments were carried out to explore the adsorption kinetics and thermodynamics of Sr2+ on bentonite and zeolite A. The results show that the adsorption capacity of bentonite and zeolite depends on the initial concentration of Sr2+, and the trends of adsorption behavior with respect to the initial concentration and adsorption time is roughly the same for bentonite and zeolite. The isotherm adsorption process of Sr2+ on bentonite and zeolite conforms to the Langmuir isotherm adsorption model. The adsorption mechanism of Sr2+ on bentonite and zeolite is similar, both based on cation exchange adsorption in monolayer. The kinetics of adsorption follows a pseudo-second-order kinetic adsorption process controlled by chemical reaction. The bentonite and zeolite before and after adsorption were characterized by XRD and SEM. The adsorption of bentonite and zeolite in acidic solution did not severely damage or affect their intrinsic framework structures. The adsorption capacity of A zeolite for Sr2+ is about 3.9 times of that of bentonite, showing a better adsorption capability than bentonite.

Key words:Bentonite; Alkali fusion activation; Zeolite; Adsorption; Strontium