Perchlorate uptake by organosilicas, organo-clay minerals and composites of rice husk with MCM-48

A variety of oraganosilicas such as MCM-41 and MCM-48 and composites of rice husks with MCM-48 were synthesized under an array of conditions and characterized by powder X-ray diffraction (XRD). Various MCM-41 mesoporous materials were prepared at room temperature using different surfactants. MCM-48 silica and its composites with rice husks were synthesized under hydrothermal conditions using cetyltrimethylammonium (CTMA) bromide and rice husks. Both untreated and carbonized rice husks were used for preparing composites of rice husk with MCM-48. Organo-clay minerals procured from two commercial sources were also investigated for their perchlorate uptake. Among the MCM-41 materials, the sample prepared from octadecyltrimethylammonium (ODTMA) chloride showed the highest perchlorate uptake capacity of 0.227 ± 0.006 meq/g while MCM-48 showed the highest perchlorate uptake capacity of 0.437 ± 0.011 meq/g among all the oraganosilicas and organo-clay minerals tested here. The uptake of perchlorate by organosilicas and organo-clay minerals is due to residual positive charge on the surfactants located in the mesopores of organosilicas and interlayers of organo-clay minerals.