A DFT study of the Pb ion adsorption on smithsonite (1 0 1) surface in aqueous system

Abstract

Understanding the adsorption mechanism of Pb ion on smithsonite surface is crucial for the sulphidation xanthate flotation of smithsonite. In this paper, the adsorption mechanism of Pb ion on smithsonite (101) surface in aqueous system was first investigated by DFT simulation. We further considered the effect of water solvent and analysed the structures of Pb ion hydrates in aqueous system, and finally the [PbOH(H2O)4]+ and Pb(OH)2(H2O)2 were employed as the main solvation components to study the Pb ion adsorption. Then, the adsorption behaviour and bonding mechanism of which on smithsonite surface were studied by analysing the adsorption configurations and electronic properties. We found that the hollow site with an eight-membered ring was the main adsorption site. In addition, H-bond played an important role in the stability of the adsorption configurations of the Pb ion hydrates on smithsonite surface. Moreover, we found that the bonding of Pb-O was mainly attributed to the hybridization of Pb 6s and Pb 6p orbitals with O 2p orbital and hybridization of Pb 5d orbital with O 2s orbital, and the formed PbO bond exhibited some ionic bond characteristic. The obtained adsorption structures corresponded well with the previous experiment.