Adsorption of SO42- on Li2CO3 crystal surfaces: experiments and first-principles calculation

Abstract

Salt lake brine is an important raw material for Li 2 CO 3 preparation, however, the composition of salt lake brine is relatively complicated, and the coexistence of impurity ions affects the quality of Li 2 CO 3 crystals. Especially, SO 42– in brine can compete with CO 32– to form ion pairs, which limits the nucleation of carbonate. Therefore, it is necessary to study the adsorption behavior of SO 42– in brine on the surface of Li 2 CO 3 crystals. In this paper, the effect of SO 42– on Li 2 CO 3 crystals under different SO 42– /Li + ratios is studied by combining experiments and first-principles calculation. The results show that in the Li 2 CO 3 crystallization system, SO 42– interacts strongly with the crys - tal surface, which is regarded as chemical adsorption. And because of the SO 42– is a soluble anion, its elution rate is about 50%. The adsorption of SO 42– on the surface of Li 2 CO 3 affects the morphol - ogy, particle size, and purity of the crystals. The governing equation is constructed by the change of the crystal specific surface area with the SO 42– /Li + ratio, which can effectively predict the crystal size and specific surface area with SO 42– content. The first-principles calculation reveals the microscopic behavior of SO 42– adsorption on the crystal surface from the molecular level that there is charge transfer between the O atoms of SO 42– and the Li atoms on the crystal surface, and there is a strong interaction between them.