Application of fly ash supported titanium dioxide for phenolphotodegradation in aqueous solution

Abstract

The photodegradation of phenol in aqueous solution using fly ash supported titanium dioxide (TiO₂/fly ash) was investigated. The TiO₂/fly ash was prepared by immobilization of TiO₂ on municipal solid waste fly ash using sol–gel-adsorption method, followed by calcination at different temperatures from 300 to 600 °C in a nitrogen atmosphere. The effects of calcination temperature, photocatalyst dosage, initial concentration of phenol and irradiation time on the photodegradation of phenol were studied. It was found that phenol could be removed rapidly from water by TiO₂/fly ash and the sample calcined at 500 °C exhibited the highest phenol photodegradation efficiency, the degradation percentage of phenol could reach 94.35% when irradiation time was 4 h, the photodegradation of phenol was obviously improved when the photocatalyst was used. Kinetics analysis showed that the photocatalytic degradation reaction could be described by a first-order rate equation. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed, the photocatalytic activity of TiO₂/fly ash remained ca. 90% of photocatalytic activity of the fresh sample after being used four times. Moreover, TiO₂ was tightly bound to fly ash and could be easily handled and recovered from water.