(376bh) Selective Adsorbents Based on Thia-Crown Ether Functionalized Composite Mesoporous Silica for Selective Recovery of Silver Ions from Aqueous Sources

Selective recovery of valuable metals in great demand like silver (Ag) from aqueous sources has been big challenge due to the large concentration difference between the target metal ions and the competing base metal ions in the medium.

Herein, highly selective and recyclable composite adsorbents were successfully developed for selective recovery of Ag(I) ions (Ag⁺). The adsorbents are composed of thiacrown ethers (thia-CEs) as Ag⁺-specific ionophores functionalized on mesoporous silica with well-defined pores as support material.The adsorbents (thia-CE@SBA-15) were prepared through immobilization of thia-CEs onto the surface of 3-(chloropropyl)triethoxysilane (CPTES) functionalized mesoporous silica (SBA-15).Various thia-CEs were synthesized by intermolecular cyclization of bulky epoxides with 1,2-benzenedithiol. Bulky epoxides with different sizes were synthesized via etherification of corresponding alkene halides with 2,2-diethylpropandiol followed by epoxidation of alkenes. Moreover, syntheses of thia-CEs were optimized by varying the metal templates, reactant concentrations, reaction solvents, time, and temperature. The synthesized thia-CE intermediates and final thia-CE products, SBA-15, and thia-CE@SBA-15 were thoroughly characterized by high-resolution spectroscopic methods such as ¹H and ¹³C NMR, FTIR, HRMS, SEM, XRD, TGA, XPS and BET. On-going works are focused on the adsorption properties of thia-CE@SBA-15 for the selective recovery of Ag⁺. Current results suggest the strong potential of thia-CE@SBA-15 as selective Ag⁺adsorption.

This research was supported by the National Research Foundation of Korea (NRF) under the Ministry of Science and ICT (No. 2017R1A2B2002109) and the Ministry of Education (No. 22A20130012051(BK21Plus)).