Ozone is an excellent disinfectant and oxidant. Phthalate acid is a typical organic acid that with a good complex adsorption capacity. In this study, experiments were carried out to investigate the influence of adsorption to the catalytic ozonation. The removal of PA, the influence of tert-butanol and the ozonation mechanism during the catalytic zonation by Cerium Dioxide (CeO
) were discussed. The results indicated that the catalytic ozonation by cerium oxide could increase the removal of PA, and after adding the tert-butanol, the removal of PA did not reduce. As the surface Ce (IV) of CeO
was a strong Lewis acid, it was easily to absorb PA and ozone to form the intermediates, the adsorption of organic matter increased the reactivity. CeO
in the process of catalytic ozonation played the role of adsorbent and catalyst.