Study on the enhancement mechanism of Pb ion on smithsonite sulfidation with coordination chemistry and first-principles calculations

Abstract

Herein, coordination chemistry analysis and first-principles calculations were creatively employed to investigate the enhancement mechanism of Pb ion on smithsonite sulfidation. The results showed that the reactivity of the Pb ion modified smithsonite surface increased, and HS was found to weakly combine with the low-spin Zn on the smithsonite surface due to the inert Zn 3d orbital while strongly interact with the Pb on Pb modified surface due to the intense ionic polarization interaction caused through the center deviations between the bonding atoms but not the π back-bonding. The Mulliken bond population and PDOS analysis further demonstrated that the bonding of Pb-S was stronger than that of Zn-S. In addition, HS was found to be more likely to break through the hydrated layer on Pb ion modified smithsonite surface. The above two reasons resulted in the enhancement of Pb ion on smithsonite sulfidation. Moreover, analysis results showed that the orbital peaks of smithsonite surface around the Fermi level were depleted after HS adsorption on the Pb ion modified smithsonite surface, and thus a more stable sulfidation product was generated. This work sheds some new light on the enhancement mechanism of Pb ion on smithsonite sulfidation.