Effect of the synthesis variables of TiO2 on the photocatalytic activity towards the degradation of water pollutants

Abstract

In this work, TiO2 photocatalysts were synthesized using a conventional sol-gel and hydrothermal synthesis methods with steam pressure treatment. Photocatalysts were characterized by X-ray diffraction (XRD), diffuse reflectance spectra (DRS) and N2 adsorption-desorption. The photoactivity of the samples was analyzed towards the photooxidation of the azo dye Orange II (Or-II) and phenol using different illumination set-ups to compare the activity features of photocatalysts. The effect of the synthesis variables such as the synthesis route, water/alcoxide and alcohol/alcoxide ratios, as well as the alcohol type was analyzed. TiO2 photocatalysts obtained by hydrothermal synthesis have a better photoactivity than the particles synthesized by the chosen sol-gel route, reaching the Or-II degradation photoactivity of the commercial TiO2 P25. On the other hand, the water/alcoxide ratio and alcohol type have a marked effect on the photoactivity of the hydrothermal synthesized TiO2, whereas the alcohol/alcoxide ratio does not have a relevant effect on the Or-II degradation photoactivity.