Photochemical treatment of phenol aqueous solutions using ultraviolet radiation and hydrogen peroxide

The potential of purifying phenol aqueous solutions (0.0006-0.0064 M) using ultraviolet (UV) radiation and hydrogen peroxide (H₂O₂; 0.005-0.073 M) was investigated. Although the direct photolysis of phenol and its oxidation by hydrogen peroxide (without ultraviolet light) were insignificant, the combination of UV and H₂O₂ was extremely effective on phenol degradation. However, the chemical oxygen demand was on no occasion entirely eliminated, indicating the resistance of the intermediate products formed to the photo-oxidation. Increasing the initial concentration of phenol had as a result lower phenol conversions achieved, whereas the increase in hydrogen peroxide initial concentration enhanced significantly the degradation of phenol. In contrast, COD removal was less sensitive to these changes.