Photodegradation of phenol using TiO2, ZnO and TiO2/ZnO catalysts in an annular reactor

In recent years the incorporation of ZnO as a semiconductor into other catalysts, for enhancing photodegradation processes, has gained attention. This paper describes the synthesis of a blend of metal oxide (TiO2/ZnO) photocatalyst and subsequent testing of the catalyst for the degradation of phenol in an annular photoreactor. The concentration of phenol before and after degradation was determined using Ultra-Violet-Spectroscopy (UV-Vis). Calcined TiO2/ZnO composite material with a mass loading ratio of 1: 1 exhibited the highest percentage phenol removal compared to the unblended TiO2 and ZnO systems at pH 7.2 and temperature of 25°C. It was shown that about 98% phenol degradation could be achieved at initial phenol concentration of 10; 20 and 50 ppm, except for 100 ppm which gave less than 50% degradation. Thus, TiO2/ZnO blend as photocatalyst can be used for degradation of phenol in water. The pseudo-first order reaction kinetics fitted well the Langmuir-Hinshelwood model in almost all concentration ranges tested.