First-Principles Insights into the Selective Separation of MoS42- and WO42-: Crucial Role of Hydration Structures

MJ Han and D Fan and CY Zhang and HZ Liu and Y Pei and J Li and JH Chen and W Sun and ZW Zhao, INORGANIC CHEMISTRY, 63, 19518-19526 (2024).

DOI: 10.1021/acs.inorgchem.4c01484

The selective separation of MoS42- and WO42- using quaternary ammonium salt through solvent extraction or ion exchange methods has been wellestablished in the metallurgical industry. However, the conventional electrostatic adsorption theory falls short in explaining the separation mechanism. Through firstprinciples density functional theory (DFT) calculations and newly self-developed deep potential molecular dynamics (DPMD) simulation method, our work first reveals that the disparity in hydration structures of MoS42- and WO42- plays a crucial role in their selective separation. It is proposed that MoS42- and WO42- anions undergo hydration to form MoS4(H2O)n2- and WO4(H2O)n2-, respectively, facilitated by hydrogen bond (H-bond) interactions. Emphasis is placed on the discrepancy between MoS42and WO42- in hydration structures by the hydration energy, Hirshfeld charge, evaluation of weak interactions, hydration radius, hydration coordination number, and H-bonds distribution. MoS42- presents a larger first hydration radius and a lower first hydration coordination number due to weaker interactions with H2O, while WO42- is subjected to enhanced hydration shielding, resulting in MoS42- anions being more susceptible to be selectively separated by a quaternary ammonium salt. This insight paves the way for the selective separation of MoS42- and WO42-, further bridging the gap between theory and industry applications.

Return to Publications page