How anatase TiO₂ with {101} {001} and {100} surfaces affect the photooxidation process of roxithromycin

TiO₂ crystals are widely used in photocatalytic processes due to their low cost and fabulous catalytic performance. As described in our previous study, three types of TiO₂ with the main surfaces of {101}, {001} and {100} were synthesized. In this study, the three types of TiO₂ are used to investigate roxithromycin (ROX) photocatalytic degradation kinetics and the pH effect. For photocatalytic degradation, the obtained data have shown that the overall order of optimal degradation is shown as {101} > {001} > {100}. The photooxidation kinetics for {101} facet conforms to first-order kinetics at from pH 5 to pH 10, and most of the photooxidation kinetics for {001} and {100} facets are fitted well with the zero-order and second-order kinetics, respectively. The pH effects are varied to the three types of TiO₂, of which {101} has the best degradation effect at pH values 4, 7 and 8, while {001} works best at pH 5 or pH 6, and {100} has a relatively obvious effect at pH 4 and pH 9. The relation between adsorption and oxidation has been tested and proved that the strong adsorption corresponds to the fast oxidation.