Lifetime and Regeneration Studies of Various Supported TiO₂ Photocatalysts for the Degradation of Phenol under UV-C Light in a Batch Reactor

Combined photolysis and predominantly photocatalytic degradation of phenol under UV-C light (λ = 254 nm) with the maximum intensity of 5400 μW/cm 2 was carried out in a batch reactor. The TiO 2 photocatalysts were supported on glass beads, silica gel, and quartz sand using a sol−gel method. The supported TiO 2 catalysts were characterized by XRD, SEM, and EDX analyses. Factors affecting the photocatalytic degradation of phenol such as pH, oxygen supply rate, initial phenol concentration, and H 2 O 2 concentration were investigated. TiO 2 supported on quartz sand gave the highest efficiency with 90% degradation of 50 mg/L phenol solution in 6 h, followed by TiO 2 supported on silica gel and glass beads with 86% and 74%, respectively. The higher photoactivity of supported TiO 2 on quartz sand was ascribed to the high crystallinity and high quantity of Ti, and the absence of ions which could inhibit the crystallization on the catalyst surface. The supported TiO 2 was found to be stable for repeated use. The results suggested that TiO 2 /quartz sand and TiO 2 /glass beads gave very good performances in the phenol degradation reaction. However, with TiO 2 /silica gel, the percentage of degradation decreased to about 11% when used for the second time and then the percentage of degradation decreased slightly when reused again in the third and fourth runs.