Synthesis of thiol functionalized organo-ceramic adsorbent by sol-gel technology

A new high performance adsorbent (SOL-AD) is synthesized by the sol-gel processing technique for the purpose of treatment of cadmium and mercury ions contaminated aqueous streams. In order to synthesize this adsorbent, the functional precursor (3-merceptopropyltrimethoxysilane) and the cross-linking agent (tetraethoxysilane) are hydrolyzed and co-condensed in an acidic water and ethanol mixture followed by gelation in a basic solution. This organo-ceramic adsorbent has high uptake capacities for cadmium and mercury ions. Especially, SOL-AD-IV synthesized at the optimal conditions has uptake capacities of 222 and 1284 mg/g of cadmium and mercury ions, respectively. These uptake capacities are considerably higher than those of covalently functionalized ceramic adsorbents and other functionalized polymeric resins. In addition, the beneficial properties of ceramic adsorbents, such as strong mechanical, thermal, and chemical stabilities are maintained. This paper discusses the effects of sol-gel processing pa rameters on the properties of SOL-AD adsorbents and the adsorption/desorption of cadmium and mercury ions on the SOL-AD-IV adsorbent.