Reaction Mechanism of 2‐Methylisoborneol and 2,4,6‐Trichloroanisole in Catalytic Ozonation by γ‐AlOOH: Role of Adsorption

In this investigation, the role of adsorption mechanism of taste and odor chemicals (T&O) in catalyzed ozonation was studied to explain the selectivity in this advanced oxidation process. The selectivity degradation of 2‐methylisoborneol (MIB) and 2,4,6‐trichloroanisole (TCA) in catalytic ozonation by γ‐AlOOH (HAO) was observed, where the removal efficiency was 27.5 and 79.3% for MIB and TCA, respectively. Radical scavenger tests suggested that catalytic ozonation of TCA followed a hydroxyl radical (•OH) reaction mechanism as over 99% degradation by •OH in phase I. Degradation of MIB was dominated by the solid surface mechanism as only 63.92% degradation was deduced by •OH. According to the results of the adsorption kinetics and isotherm, the adsorbed amount of MIB on the surface of HAO by chemical adsorption was over ten times larger than that of TCA. The adsorption of T&O on HAO inhibited the generation of •OH, according to the variation of ratio of hydroxyl radical concentration to ozone concentration, Rct. Chemical adsorption between HAO and T&O was the key factor that determined the reaction mechanism of catalytic ozonation.