High -Rate Degradation of Dichloromethane by Combination of UV Irradiation and Consecutive Addition of Hydrogen Peroxide

摘要

Degradation kinetics of dichloromethane in water were investigated in a rectangular quartz cell under combination of UV irradiation and hydrogen peroxide (H_2O_2) addition. The presence of H_2O_2 not only enhanced the degradation rate of dichloromethane but prevented the forma- tion of other chlorinated organic compounds as transient intermediates to mineralization. Since H_2O_2 was consumed by UV at a much higher rate than dichloromethane, it was found that the consecutive addition of H_2O_2 was highly effective to maintain high-rate degradation of dichlor- omethane. When 2,000 mg·l~(-1) of H_2O_2 was added every 5 min, the decomposition rate of 1,500 mg· l~(-1) dichloromethane exhibited 9.3 times higher than that of one-time addition of H_2O_2. Moreover, we successfully demonstrated that the degradation rate of dichloromethane was almost proportional to the square of incident light intensity.