Using ESR to Analyze Some Oxidants Enhancing TiO2 to Produce Hydroxyl Radicals under Visual Lights

摘要

Several oxidants, KMnO4, K2Cr2O7 and CuCl2 could enhance photo-degradation organic pollutants through titanium dioxide (TiO2) in solution. By orthogonal experimental design and variance analysis study, the optimal de-coloring Acid Orange 7 (AO7) could be determined among different types and concentrations of oxidants as well as different wavelength of visual lights. The optimal removal of color could reach 99% and 92% for total organic carbon (TOC). Using 5,5-dimethyl-l-pyrroline-noxide (DMPO) to scavenge the hydroxyl radicals (?OH) produced during photocatalysis reaction and to analyze by the Electron Spin Resonance Spectrum (ESR), the effects of oxidants were to promote the production of OH as TiO2 shining even by visual lights which the wavelengths were less than the excitation energy of band-gap.