Decomposition of Acid Dye by TiO2 Thin Films Prepared by the Sol-Gel Method

Textile plants exhaust a great deal of water and generate a great deal of wastewater with high color contents, high suspended solids, and dissolved organics. To meet increasingly stringent environmental regulations, many technologies are used to remove toxic nonbiodegradable organic matters from the wastewaters. In this study, TiO2 thin films coated on glass bottles for use as photocatalytic reactors to decompose dye in aqueous solutions were prepared by the sol-gel method, followed by coating, drying, and calcination. An experimental design methodology was adopted to screen the most important factors and to search for the optimal preparation conditions. According to the Plackett-Burman design, the alcohol-to-titanium ratio, the acid-to-titanium ratio, and the sol-gel reaction time were found to be the most important variables that might affect the final TiO2 film performance in terms of dye decomposition efficiency. The maximum dye decomposition efficiency was found, by the simplex method, to be 49.2% under 4-W UV illumination for 6 h.