Selective and high capacity recovery of aqueous Ag(I) by thiol functionalized mesoporous silica sorbent.

[Display omitted] • Simplified preparation of thiol functionalized short range ordered mesoporous silicas. • Selective sorption of aqueous Ag(I) with a capacity of 238 mg g−1 at pH = 5.0. • Sorption equilibrium establishes extremely fast, in 15 min contact time. • Strong and selective binding of Ag(I) due to the formation of layered thiolate coordination compounds on the surface. • Quantitative recovery of Ag(I) and sorbent regeneration with 10 mM Na 2 S 2 O 3 solution. A simplified sol–gel method was developed for the preparation of thiol functionalized porous silica particles using (3-mercaptopropyl)-trimethoxy-silane (MPTMS) for co-gelation in the presence of micellar templates. The resulting short range ordered porous silica microparticles are exceptionally effective sorbents of aqueous Ag(I). The binding of aqueous Ag(I) is almost stoichiometric in the broad pH range between 4.0 and 9.0 even at low Ag(I) concentrations until reaching the limiting 238 mg g−1 sorption capacity. The sorbent displays high selectivity towards Ag(I), which was tested in the simultaneous presence of several different metal compounds. The practically complete recovery of Ag(I) and the regeneration of the sorbent was achieved by washing with a 10 mM Na 2 S 2 O 3 solution. X-ray photoelectron spectroscopy (XPS) revealed that silver is not reduced on the surface of the sorbent. The reason for the strong and selective binding of Ag(I) is the formation of layered thiolate coordination compounds on the functionalized silica surface that display characteristically high stability even in the presence of other competing metal ions. [ABSTRACT FROM AUTHOR]