Application of ZnO Nanoparticles Impregnated with Rose Bengal Dye in Photocatalytic Degradation of Phenolic Pollutants under Visible Light Irradiation

In this research, spherical ZnO nanoparticles (ZnO NPs) and also ZnO nanoparticles impregnated with Rose Bengal dye (dye/ZnO) were synthesized easily by a new method. The resulting particles with the visible light absorption ability were used as modified photocatalysts for the degradation of phenolic pollutants. ZnO nanoparticles and dye/ZnO were identified with X-Ray Diffraction (XRD) analysis, Fourier Transform InfraRed (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), thermal analysis (TGA/DSC), and UltraViolet-Visible spectroscopy (UV-Vis). The energy gap of dye/ZnO was calculated to be about 2/9eV. Experiments showed degradation of phenol by dye impregnated ZnO nanoparticles under visible light has better efficiency in comparison with the pure ZnO nanoparticles. At the time of 130 minutes, dye/ZnO nanoparticles could degrade approximately 96% of phenol, while the pure ZnO nanoparticles had 10% efficiency at the same time. The mechanism of the reaction is based on the optical excitation of both ZnO semiconductor and dye molecules and then charge transfer.