Density Functional Study to Investigate the Ability of (ZnS)n (n = 1–12) Clusters Removing Hg0, HgCl, and HgCl2 via Electron Localization Function and Non−Covalent Interactions Analyses

Abstract

In this study, the density functional theory is used to study the ability of (ZnS)n clusters to remove Hg0, HgCl, and HgCl2 and reveals that they can be absorbed on (ZnS)n clusters. According to electron localization function (ELF) and non−covalent interactions (NCI) analyses, the adsorption of Hg0 on (ZnS)n is physical adsorption and the adsorption ability of (ZnS)n for removing Hg0 is weak. When (ZnS)n adsorbs HgCl and HgCl2, two new Hg−S and Zn−Cl bonds form in the resultant clusters. An ELF analysis identifies the formation of Hg−S and Zn−Cl bonds in (ZnS)nHgCl and (ZnS)nHgCl2. A partial density of states and charge analysis confirm that as Hg0, HgCl, and HgCl2 approach (ZnS)n clusters, atomic orbitals in Hg and Zn, Hg and S, as well as Zn and Cl overlap and hybridize. Adsorption energies of HgCl and HgCl2 on (ZnS)n clusters are obviously bigger than those of Hg0, indicating that HgCl and HgCl2 adsorption on (ZnS)n clusters is much stronger than that of Hg0. By combining ELF analysis, NCI analysis, and adsorption energies, the adsorption of HgCl, and HgCl2 on (ZnS)n clusters can be classified as chemical adsorption. The adsorption ability of (ZnS)n clusters for removing HgCl and HgCl2 is higher than that of Hg0.

Interaction behavior study of HCl on (ZnS)n (n = 1–12) clusters and HCl effect on Hg0 adsorption

“…(ZnS) n structures have been given and discussed in detail in our previous work [22], thus the structures of them will not describe here. Here we only give the descriptions of (ZnS) n HCl and (ZnS) n HgHCl clusters.…”

“…H and Cl atoms are far apart in 2b, and H⋯Cl bond distance is 6.67 Å. Compared to 3a of (ZnS) 3 [22], 3b turns to an open structure through breaking of one ZnS bond in 3a. In 3b, H and Cl atoms in HCl forms SH and ZnCl bonds, and their bonds are 1.35 and 2.15 Å, respectively.…”

“…The noncovalent interaction (NCI) analysis method and its formula has been given in our previous work in detail [22]. From the adsorption analysis, absolute values of E ads and E int of (ZnS) 10 HgHCl are the biggest for (ZnS) n HgHCl family.…”

“…Yang et al synthesized zinc sulfide with different crystal structures and used to adsorb Hg 0 [2], which indicated that Hg 0 removal performance depends on specific area and sulfur activity sites. Recently, we studied the structures and bond properties between neutral (ZnS) n ( n = 1 – 12) clusters and Hg 0 , HgCl, HgCl 2 using PBE0‐D3/def2‐TZVP method and predicted that (ZnS) n clusters can chemically adsorb HgCl and HgCl 2 and physically adsorb Hg 0 [22].…”