Removal of VOCs in waste gas by the photo- Fenton reaction: effects of dosage of Fenton reagents on degradation of toluene gas in a bubble column

BACKGROUND: Volatile organic compounds (VOCs) are major pollutants in the atmosphere of all urban and industrial areas, and the development of an effective treatment process for VOCs is highly desirable. Advanced oxidation processes (AOPs) are a promising technology for air pollution control. In this study, the AOP photo-Fenton oxidative reaction in the liquid phase was applied to chemical absorption and degradation of toluene in waste gas. RESULTS: For toluene levels of 0.25 mg L-1 in waste gas flowing at 5.0 Lmin(-1) the maximum removal and mineralization of toluene in the waste gas were more than 90% with H2O2 dosage above 150 mg L-1 and Fe dosage above 10 mg L-1. The Toluene photodegradation efficiency increased with increasing dosages of Fenton reagents, however, beyond a certain dosage further improvements were insignificant. The photo-Fenton reaction in the liquid-phase could improve the overall toluene absorption rate by increasing the driving force for mass transfer and as a result enhance the removal of toluene from exhaust gas. CONCLUSION: Toluene in waste gas was successfully removed and mineralized by the photo-Fenton process. The mineralization of toluene was strongly linked with the iron redox cycle and H2O2 decomposition driven by the Fenton reagents and UV light. The proposed chemical absorption process based on photo-Fenton photocatalytic oxidation in the liquid phase was shown to be very effective for the degradation of VOCs in waste gas. (C) 2012 Society of Chemical Industry