Mechanism confirmation of heterogeneous catalytic ozonation by ceramic honeycomb for the removal of organic compound in aqueous solution

To confirm the mechanism of heterogeneous catalytic ozonation, experiments were performed to compare the degradation of nitrobenzene in different systems. The initiation of HO and oxidation intermediates were determined by ESR, GC/MS and IC. The experimental results indicated that the degradation of nitrobenzene in aqueous solution followed the oxidation mechanism of HO in both the processes of ozonation alone and the ceramic honeycomb catalytic ozonation. Comparing with the ozonation system alone, the process of ceramic honeycomb catalytic ozonation could initiate higher concentration of HO, leading to the obvious increase in TOC removal. It was found that some intermediates were formed respectively during the decomposition of nitrobenzene in both the processes of ozonation alone and ceramic honeycomb catalytic ozonation. The results of GC/MS and IC analysis indicated that the major intermediates were nitrophenols, multi-hydroxy derivatives and low molecular weight organic acids. Phenol, hydroquinone, benzoquinone and nitrate ion were also detected as intermediates. A general reaction pathway for the degradation of nitrobenzene involving intermediates was proposed.