Novel relationship between hydroxyl radical initiation and surface group of ceramic honeycomb supported metals for the catalytic ozonation of nitrobenzene in aqueous solution

Comparative experiments have been performed to investigate the degradation efficiency of nitrobenzene and the removal efficiency of TOC in aqueous solution by the processes of ceramic honeycomb supported different metals (Fe, Ni, and Zn) catalytic ozonation, indicating that the modification with metals can enhance the activity of ceramic honeycomb for the catalytic ozonation of nitrobenzene, and the loading percentage of metal and the metallicity respectively presents a positive influence on the degradation of nitrobenzene. The degradation efficiency of nitrobenzene is determined by the initiation of hydroxyl radical (^•OH) according to a good linear correlation in all the processes of modified ceramic honeycomb catalytic ozonation at the different loading percentages of metals. The modification of ceramic honeycomb with metals results in the conversion of the pH at the point of zero charge (pH_PZC) and the evolution of surface groups. Divergence from the conventional phenomenon, the enhancement mechanism of ozone decomposition on the modified ceramic honeycomb with metals is proposed due to the basic attractive forces of electrostatic forces or/and hydrogen bonding. Consequently, a novel relationship between the initiation of •OH and the surface-OH ₂⁺ group on the modified catalyst is established based on the synergetic effect between homogeneous and heterogeneous reaction systems.