Synthesis, characterization and application development of ordered mesoporous silica in wastewater remediation

This study describes the total removal of multiple heavy metal ions from wastewater using organo-functionalized ordered mesoporous silica MCM-41. Hydrothermal synthesis of siliceous MCM-41 was done using sodium silicate as precursor through a new cost-effective and environmentally friendly silica precipitation method. Functionalization of siliceous MCM-41 by thiol-containing organosilane was done through a post-synthesis grafting route at room temperature. Physicochemical characterization reveals that the resultant materials have highly ordered hexagonal mesoporous structure and high BET surface area in the range of 1000‒1200 m2/g, before and after organo-functionalization. The organo-functionalized mesoporous materials have been applied for adsorption of a mixture of heavy metal ions from wastewater at room temperature, where the heavy metal ions covalently bind non-selectively with the pendant thiol moieties inside the mesopores. As envisaged from elemental analyses using atomic emission spectroscopy, high efficiency of heavy metal ion adsorption from wastewater was observed, which was significantly better than that of standard adsorbents.