Adsorption of Strontium by Vermiculite and Montmorillonite

The adsorption of Sr²⁺ by vermiculite and montmorillonite and the effects of experimental conditions were investigated. The results show that more than 96.8% and 98.5% of the total Sr²⁺ can be adsorbed by the vermiculite and montmorillonite from pH=8 Sr²⁺ solution of 20 MBq/L (C₀) at room temperature, respectively. The equilibrium of adsorption by vermiculite and montmorillonite was achieved within 2 h and 15 min severally, and the optimum pH both ranged from 3 to 10. More than 82.7% and 98.7% Sr²⁺ can be desorbed by 2 mol/L HNO₃ solution from the vermiculite and montmorillonite.The adsorption rate of Sr²⁺ by vermiculite and montmorillonite will decrease in presence of coexistent Ca²⁺, while modified by Ag（NH₃)₂⁺ and 1 mol/L HCl can improve the adsorption abilities of vermiculite for Sr²⁺,but decreased by high temperature.As for montmorillonite, modified by Cu(NH₃)₄²⁺ can improve adsorption, however, by Ag（NH₃)₂⁺ and high temperature can decrease. Additionally, the modified vermiculite and montmorillonite were analyzed by X-ray diffractometer system (XRD). The results show that the spectra of the modified vermiculite or montmorillonite are different from that of the original one.