The Properties and Activity of TiO₂ /beta-SiC Nanocomposites in Organic Dyes Photodegradation

The TiO₂ /beta-SiC nanocomposites containing 0-25 wt. % of beta-SiC were synthesized by the sol-gel method and tested in the photodegradation of methylene blue and methyl orange water solutions. With the increase in SiC content, only a slight decrease in energy band gap was observed (3.19-3.12 eV), together with significant increase in the surface area of the catalysts (42.7-80.4 m² g^-1 ). In the synthesized material, the anatase phase of TiO₂ was present in the form of small agglomerates resulting from the mechanical mixing process. In the process conditions (catalyst concentration 0.5 g L^-1 , initial dye concentration 100 ppm, light source 100 W UV-Vis lamp), we have observed no signs of catalyst deactivation. The significantly higher photodegradation activity of methylene blue than methyl orange can be attributed to the preferable pH of the solution compared to pH_PZC and the cationic character of the first dye. In case of methyl orange, pH process conditions substantially limit the contact of the catalyst with the dye, as negatively charged surface of the catalysts repels the dissociated anionic dye molecules.