Chemical and structural properties of silica obtained from rice husk and its potential as a catalytic support

Abstract

The structural and chemical properties of biogenic silica obtained from rice husk using an acid treatment were determined in order to explore its potential as a support in the synthesis of catalysts for the remediation of contaminants in water. Using thermogravimetric analysis (TG-DTG) the total amount of silanol groups on the surface was quantified and by means of DRIFT spectroscopy and TPR-NH3 analysis, the amount of silanol groups present (isolated, geminal and vicinal) were identified and quantified. The silica structure was confirmed by XRD and a silica content of 99.3% was determined by XRF. The zeta potential measurements revealed an isoelectric point at pH 5.4. Finally, the presence of non-bridging oxygen centers – NBO type oxygen defects on the surface of the biogenic silica was identified by DRIFT and EPR spectroscopy techniques. New knowledge is uncovered aimed at the future exploration of rice husk silica produced by a more environmentally friendly method, as a potential support in the synthesis of catalysts.