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

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.