Comparison of the efficiency and mechanism of catalytic ozonation of 2,4,6-trichloroanisole by iron and manganese modified bauxite

The efficiency and mechanism of catalytic ozonation of 2,4,6-trichloroanisole (TCA) by metal oxide modified bauxite were studied. TCA was effectively degraded by catalytic ozonation in the presence of iron- or manganese-modified bauxite (IMB or MMB). The effect of water pH on catalytic ozonation indicated that surface property was the key factor that influenced the activity of catalyst. Analysis results of the isoelectric point (IEP) and zeta potential for catalyst further confirmed that a lower zeta potential for modified bauxite enhanced catalytic activity. Results of both catalytic ozone decomposition and radical scavengers experiments indicated that catalytic ozonation by IMB or MMB followed a hydroxyl radical (OH) reaction pathway. The main reaction pathway was proposed that adsorption of both ozone and TCA in the micropores and subsequent interaction (direct and indirect oxidation) between them that was confirmed by the analysis of the surface pore volume and surface hydroxyl groups, being followed by the diffusion of ozone and TCA on the mesoporous surface, in which surface hydroxyl groups covering mesoporous surface initialed ozone decomposition to generate OH, resulted in TCA degradation.

Reaction mechanism of modified raw bauxite catalytic ozonation of 2,4,6-trichloroanisole. The adsorption of both ozone and TCA in the micropores resulted in the subsequent interaction (direct and indirect oxidation) between them. This was followed by diffusion of ozone and TCA on the mesoporous surface. Surface hydroxyl groups covering mesoporous surface initialed ozone decomposition to generate OH, resulted in TCA degradation.Figure optionsDownload as PowerPoint slideHighlights
► Iron and manganese-modified bauxite was used as catalyst in catalytic ozonation.
► The role of surface chemical properties of modified bauxite in catalytic ozonation for removal trichloroanisole was confirmed.
► Different role of micropores and mesoporous in catalytic ozonation was determinate.