Photocatalytic degradation of dyes in water using porous nanocrystalline titanium dioxide

The degradation of the dyes methylene blue (MB), methyl orange (MO), and indigo (Ind) in water was carried out via a photocatalytic reaction. The porous nanocrystalline TiO2 photocatalysts used in the photocatalytic degradation were prepared using polyethylene glycol (PEG) as a structure-directing agent in the sol–gel system. The Taguchi experimental design method (L9(34)) was applied to determine the preparation conditions of the sol–gel process. The TiO2 photocatalyst powders obtained at the optimal preparation conditions through analysis of variance (ANOVA) could degrade methylene blue, methyl orange, and indigo in water by 57.06–84.14%, 35.15–50.09%, and 69.09–99.09%, respectively, after 10 h of UV irradiation. TiO2 thin-film photocatalyst was also prepared at the optimal preparation conditions; it exhibited good performance for the photodegradation of methylene blue, methyl orange, and indigo solution under UV light irradiation.

► Photocatalyst with porosity improves the degradation of dyes.
► PEG increases the specific surface area of TiO2 powders.
► The molar ratio of AcAc/TTIP has the greatest impact on the performance of TiO2.
► The results are useful for understanding the water purification.