TiO2 conjugated with molecules of Rose red dye as a photocatalyst towards salicylic acid

Nanoscale TiO2 was synthesized using TiCl4 as a starting material via sol-gel method. Prepared spherical TiO2 nanoparticles were conjugated with Rose red dye and used as modified photocatalysts for degradation of salicylic acid as a model of environmental pollution. TiO2 nanoparticles and dye-TiO2 system were characterized with X-ray diffraction analysis (XRD), Infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermal analysis (TGA/DSC) and spectroscopy (UV-Vis) .Based on the results of detection, the energy gap of dye-TiO2 was calculated to be 2/9eV. Experiments showed degradation of salicylic acid by dye-TiO2 system under visible light has better efficiency compared to bare TiO2 nanoparticles .At the time of 120 minutes; dye-TiO2 system could remove approximately 70% of salicylic acid, while bare TiO2 nanoparticles had 10% efficiency. The mechanism of reaction is based on optical excitation of both of TiO2 semiconductor and dye molecules fallowed by charge transfer. It is proposed that electron injection from the dye to ،TiO2 is mainly responsible for the enhancement of the reaction rate of salicylic acid degradation.