Rapid Photocatalytic Degradation of Methylene Blue under High Photon Flux UV Irradiation: Characteristics and Comparison with Routine Low Photon Flux

This study examined the photocatalytic degradation efficiency under high UV photon flux (intensity normalized by photon energy) irradiation; the incident UV photon flux was 1.71 x 10(-6)-3.13 x 10(-6) einstein cm(-2) s(-1) made by a super high-intensity UV apparatus. A comparative study between high photon flux photocatalytic process and routine low photon flux photocatalytic process for methylene blue degradation has been made in aqueous solution. The experimental results showed that under the best conditions of high UV photocatalytic reaction 99% decolorization and 95% TOC removal of 20 mg L-1 methylene blue could be achieved in 30 s and 120 s of UV irradiation time, respectively. To the best of our knowledge, photocatalytic decolorization and photocatalytic degradation of dyes in such a short time has not been reported. Aiming at the low photonic efficiency in high photon flux photocatalytic process, we found that reducing the density of excited electron-hole appropriately could improve initial apparent photonic efficiency effectively. The TOC experiments under high UV photon flux showed a faster mineralization rate and a different mineralization process compared to that under low UV photon flux.