Mercury separation and immobilization using self-assembled monolayers on mesoporous supports (SAMMS)

Mercury (Hg) is one of the most toxic metals found in the environment. The purpose of this study was to investigate the performance of an innovative technology, self-assembled monolayers on mesoporous supports (SAMMS), in separating and immobilizing Hg from aqueous solutions. The high surface area of the mesoporous silica and the covalent binding between the thiol (-SH) group in SAMMS and Hg in solution provide SAMMS with distinctive advantages over existing technologies. The results show that (i) the Hg removal is kinetically quite rapid, (ii) the sorption data follow Langmuir isotherms, (iii) the maximum sorption capacity could be up to 613 mg of Hg per gram of SAMMS, (iv) SAMMS was able to reduce Hg concentrations to below the national pollution discharge emission standard level (12 ppt), (v) the Hg-laden SAMMS was stable in aqueous solution at 70 degrees C, and (vi) the Hg-laden SAMMS was able to pass TCLP (Toxicity Characterization Leaching Procedure) tests of the U.S. Environmental Protection Agency. The results, therefore, suggest that SAMMS has a strong potential to be used for the removal and immobilization of Hg and that the Hg-laden SAMMS is suitable for longterm disposal.