Mo<sub>3</sub>S<sub>13</sub><sup>2−</sup> Intercalated Layered Double Hydroxide: Highly Selective Removal of Heavy Metals and Simultaneous Reduction of Ag<sup>+</sup> Ions to Metallic Ag<sup>0</sup> Ribbons
Lixiao Yang, Linxia Xie, Menglin Chu, Hui Wang, Mengwei Yuan, Zihuan Yu, Chaonan Wang, Huiqin Yao, Saiful M. Islam, Keren Shi, Dongpeng Yan, Shulan Ma, Mercouri G. Kanatzidis
Abstract
Abstract We demonstrate a new material by intercalating Mo 3 S 13 2− into Mg/Al layered double hydroxide ( abbr . Mo 3 S 13 ‐LDH), exhibiting excellent capture capability for toxic Hg 2+ and noble metal silver (Ag). The as‐prepared Mo 3 S 13 ‐LDH displays ultra‐high selectivity of Ag + , Hg 2+ and Cu 2+ in the presence of various competitive ions, with the order of Ag + >Hg 2+ >Cu 2+ >Pb 2+ ≥Co 2+ , Ni 2+ , Zn 2+ , Cd 2+ . For Ag + and Hg 2+ , extremely fast adsorption rates (≈90 % within 10 min, >99 % in 1 h) are observed. Much high selectivity is present for Ag + and Cu 2+ , especially for trace amounts of Ag + (≈1 ppm), achieving a large separation factor (SF Ag/Cu ) of ≈8000 at the large Cu/Ag ratio of 520. The overwhelming adsorption capacities for Ag + ( q m Ag =1073 mg g −1 ) and Hg 2+ ( q m Hg =594 mg g −1 ) place the Mo 3 S 13 ‐LDH at the top of performing sorbent materials. Most importantly, Mo 3 S 13 ‐LDH captures Ag + via two paths: a) formation of Ag 2 S due to Ag‐S complexation and precipitation, and b) reduction of Ag + to metallic silver (Ag 0 ). The Mo 3 S 13 ‐LDH is a promising material to extract low‐grade silver from copper‐rich minerals and trap highly toxic Hg 2+ from polluted water.