Catalytic activity of aluminum silicate for ozonation of chloronitrobenzenes in aqueous solution

Chemical oxidation using ozone with appropriate catalysts offers an attractive option for removing inhibitory and toxic pollutants in micro-polluted water. This work investigated the catalytic ozonation of three chloronitrobenzenes (CNBs, i.e. p-CNB, o-CNB, and m-CNB) in the presence of a novel and efficient synthesized aluminum silicate catalyst. Experiments were carried out with focus on the degradation efficiency of CNBs at different reaction pH values, water matrices and repeated uses, as well as the possible catalytic mechanism. Regardless of the water matrix, the results showed that the catalytic ozonation had considerably higher degradation efficiency of CNBs than the single ozonation process at the same ozone dose. The change of pH had an obvious effect on the removal efficiency of CNBs, which suggested that the aluminum silicate catalyst was more appropriate for application in the neutral pH condition. Ozonation processes in the presence of the aluminum silicate were significantly influenced by tert-butyl alcohol, which confirmed that the aluminum silicate catalytic ozonation followed a hydroxyl radical-type mechanism.