Release Behavior of Pb(II) Ions on the Galena Surface: Dissolution Experiment, DFT Calculation, and MD Simulation

In this study, the release behavior of Pb(II) ions from the galena surface and their occurrence forms in the migration process under acid and alkaline conditions were investigated by dissolution experiment, the density functional theory (DFT) calculation, and molecular dynamics (MD) simulation. The dissolution experiments indicated that acidic and high alkaline conditions are more beneficial for the release of Pb(II) rather than neutral and weak alkaline conditions. The quantum chemical calculations indicated that under acidic conditions, H+ can destroy the surface structure of galena, leading to the dissolution of Pb2+ from the mineral surface into the liquid phase. OH- can also damage the galena surface to a certain extent under alkaline conditions. Additionally, MD simulations were further utilized to study the occurrence forms of Pb(II) ions in alkaline solutions. The results suggested that with a certain concentration of OH-, Pb2+ ions will form lead hydroxide aggregates, while excessive OH- could lead to the dispersion and dissolution of the lead hydroxo complexes. The surface morphological observation by SEM can well support the calculation and simulation results.