Synthesis of dithiol-modified mesoporous silica adsorbent for selective adsorption of mercury ions from wastewater

A mesoporous silica adsorbent modified with 1,2-ethane dithiol was conveniently prepared by co-condensation and further surface grafting method. To achieve this synthesis, trimethoxyvinylsilane (TMVS, 20 mol%) was introduced into the silica wall framework along with tetraethoxysilane (TEOS) in the initial reaction mixture during the sol-gel condensation process. Next, to modify the dithiol groups onto the mesoporous silica adsorbent surfaces, the incorporated vinyl groups into the mesopore walls were reacted with 1,2-ethane dithiol via click reaction. The prepared dithiol-modified silica adsorbent (DTMSA) material was characterized by a range of instruments including XRD, FT-IR, N-2 sorption, and so on. The DTMSA material showed selective adsorption of mercury ions with high adsorption quantity of 252 mg/g and a removal capacity of nearly similar to 90% from the initial metal ion mixture containing other competitive metals (Zn2+, Ni2+, Pb2+, Cd2+, and Fe2+) ions. The DTMSA adsorbent showed recyclable properties up to five cycles while treating with an acidic aqueous solution (0.1 M HCl), and therefore the DTMSA adsorbent can be recycled and reused up to five times without altering the adsorption efficiency. The experimental results demonstrated that the DTMSA adsorbent might be used for selective adsorption of harmful Hg2+ ions from an aqueous solution.

Automated summary

A mesoporous silica adsorbent modified with 1,2-ethane dithiol was prepared by co-condensation and further surface grafting method, showing high selectivity for mercury ions and recyclable properties.