Effect of Ultrasound on the Properties of Heterogeneous Catalysts for Sono-Fenton Oxidation Processes

Abstract

AbstractThe objective of this research is to assess the effect of ultrasonic irradiation (20 KHz) on the catalytic activity and catalyst particle size of different iron-containing solids (hematite/SBA-15 nanocomposite; hematite; goethite). The catalytic activities of the different catalysts were investigated in the sono-Fenton degradation of a phenolic aqueous solution in the presence of hydrogen peroxide at pH 3. The catalytic performance was monitored in terms of phenol and total organic carbon (TOC) conversions. The concentration changes of different by-products coming from incomplete mineralization of phenol were also monitored. The stability was examined by measuring iron dissolved in the reaction medium after reaction. The degradation rate in the presence of the nanocomposite material was higher than that when SBA-15 and hematite were separately suspended and also higher than that found for the bulk and unsupported iron oxides (hematite and goethite). The particle size of the catalysts suffers serious changes during the sonication which strongly depend on their nature. Unlike nanocomposite material which presents a deep catalyst particle reduction, unsupported bulk iron oxides yield an agglomeration of the particles. The considerable enhancement of the activity achieved with the nanocomposite material is due to the catalyst particles size reduction during ultrasound irradiation as well as the high dispersion of the metallic species over the mesostructured support.