Organosilicas and organo-clay minerals as sorbents for toluene

This study investigated the adsorption of toluene as a non-ionic organic contaminant by organosilicas and organo-clay minerals. Different organic surfactants were used to prepare a variety of MCM-41 molecular sieves at room temperature while cetyltrimethylammonium (CTMA) bromide was used to synthesize MCM-48 mesoporous material under hydrothermal conditions. Organo-clay minerals were synthesized under hydrothermal conditions using synthetic low-charge Na-fluorophlogopite micas with CTMA bromide as organic surfactant. All synthetic organosilicas and organo-clay minerals, the latter including those procured from two commercial sources were characterized by powder X-ray diffraction (XRD) and their toluene sorption properties were investigated. Among organosilicas, MCM-48 exhibited the highest distribution coefficient (K_d) value of toluene (95±9L/kg). An organo-clay mineral, Nanomer® PGW montmorillonite modified with CTMA bromide (Nanomer® 1.28E) showed the maximum K_d value (345±22L/kg) for toluene among all the studied organosilicas and organo-clay minerals. The organo-clay mineral nanocomposites were found to be superior to MCM-41 and MCM-48 organosilicas tested here and the former could find applications in remediating organic contaminants such as toluene from soil and groundwater.