Synthesis and Characterization of Bismuth Oxo Compounds Supported on TiO_2 Photocatalysts for Waste Water Treatment

摘要

Azo dyes are usually used in textile industry. However, they can cause water contamination, lead to water pollution, damage to aquatic lives and degenerate scenery due to their toxicity. These problems can be overcome by photocatalytic process in which the azo dyes are converted to CO_2 and water. This research concentrates on effect of Bi_2O_3, BiOBr and BiOI contents on titanium dioxide substance (TiO_2) for the photocatalytic process. In the study, photocatalysts were synthesized by sol-gel and wetness impregnation methods. They were studied in surface area by BET technique, chemical composition by FT-IR spectroscopy and optical properties by UV-DRS technique. Increase in bismuth content on TiO_2 results in decreasing surface area. In FT-IR spectra, Ti-O-Ti stretching bands at 400-800 cm~(-1) were detected. The band gap energy of these photocatalysts is decreased when bismuth was doped. Since efficiency of CO_2 and water conversion of the photocatalysts can be determined indirectly via determinaiton of decreasing Methyl Orange (MO) concentration, the lowest MO concentration was observed in the 4%Bi_2O_3T photocatalyst after 16 hours when compared to the other photocatalyst samples and Degussa P25. In other words, this photocatalyst efficiently converts the azo dyes to CO_2 and water.