Complexation and activation of fluoride ion and its acceleration for dissolution of cations on the surface of vanadium-containing biotite (0 0 2)

Abstract

Density functional theory (DFT) calculations are used to simulate the interaction between leaching agent ions (H+), complexing agent ions (F−), and a vanadium-containing biotite surface. The calculation results show that the active sites for adsorbing leaching agent ions are oxygen atoms, and the final product is water. The formation of surface water molecules leads to defects in surface oxygen atoms, and such defects lead to the isolation and dissolution of cations on the surface. The active sites for adsorbing complexing agent ions are surface cations. The adsorption of complexing agent ions can destroy the tetrahedral structure of surface cations and can also reduce the activation energy required to form surface water molecules. The two oxygen atoms connected to the vanadium element generate water, and the activation energy is decreased from 5.89 eV and 6.83 eV to 2.32 eV and 3.85 eV, respectively. When the cation is exposed, the fluoride ion can complex with the exposed cation and enter the solution to achieve the dissolution effect. This research is problem-oriented and involves experiments and a deep understanding of the mechanism for ion activation leaching on the atomic level. It has been confirmed that the complexing agent ion proposed in this work can greatly increase the leaching rate, as has been verified by electron probe, scanning electron microscopy, infrared and other methods. The reliability of simulation calculations.