Mo S Intercalated Layered Double Hydroxide: Highly Selective Removal of Heavy Metals and Simultaneous Reduction of Ag Ions to Metallic Ag Ribbons.

We demonstrate a new material by intercalating Mo S into Mg/Al layered double hydroxide (abbr. Mo S -LDH), exhibiting excellent capture capability for toxic Hg and noble metal silver (Ag). The as-prepared Mo S -LDH displays ultra-high selectivity of Ag , Hg and Cu in the presence of various competitive ions, with the order of Ag >Hg >Cu >Pb ≥Co , Ni , Zn , Cd . For Ag and Hg , extremely fast adsorption rates (≈90 % within 10 min, >99 % in 1 h) are observed. Much high selectivity is present for Ag and Cu , especially for trace amounts of Ag (≈1 ppm), achieving a large separation factor (SF ) of ≈8000 at the large Cu/Ag ratio of 520. The overwhelming adsorption capacities for Ag (q =1073 mg g ) and Hg (q =594 mg g ) place the Mo S -LDH at the top of performing sorbent materials. Most importantly, Mo S -LDH captures Ag via two paths: a) formation of Ag S due to Ag-S complexation and precipitation, and b) reduction of Ag to metallic silver (Ag ). The Mo S -LDH is a promising material to extract low-grade silver from copper-rich minerals and trap highly toxic Hg from polluted water.