Gas-phase advanced oxidation (GPAO) for benzene-containing gas by an ultraviolet irradiation/hydrogen peroxide vapour (UV/[H2O2]g) process

Hydrogen peroxide (H2O2) is a remarkably strong oxidant, and its vapour ([H2O2]g) has further advantages, such as a low cost and good light transmission. However, there has been very little research on its removal through gas-phase advanced oxidation (GPAO). In the present study, the photochemical oxidation of a gas that contains a series of benzene derivatives using ultraviolet (UV) irradiation and [H2O2]g was investigated in a transparent bag made of fluorinated ethylene propylene (FEP). UV and [H2O2]g barely reduced the pollutant within 5 h when used alone, and the reactant was also stable. When the pollutant concentration was high (248 to 756 mg/m3) and the residence time was short (3 s) compared with related studies on the removal of benzene, toluene and xylene, the apparent removal rate by UV/[H2O2]g/(powder active carbon, PAC) was higher than when other methods (UV/[H2O2]g, UV/[H2O2]g/TiO2 and UV/[H2O2]g/ZnO), were used. However, it was found that the mineralization by UV/[H2O2]g significantly decreased, which in turn decreased the conductivity after the reaction. Increasing the pollutant concentration and the pH of the H2O2 had a negative effect on the treatment, but the UV radiation had a positive effect at powers of up to 40 W. In addition, the characteristic absorbance of three benzene derivatives showed that the key structure of the pollutant molecules was damaged during GPAO.