Abstract
It has been revealed that hydrothermal oxidation of persistent organochlorine substances is dramatically facilitated with the aid of Cu-based catalysts such as Cu-supported WO3, because the Fenton-type reaction catalyzed by Cu ions undergoes substantial acceleration under subcritical conditions of water at around 200~300℃, leading to the increased formation of hydroxyl radicals which possess a strong oxidative power. In this study, the catalytic hydrothermal oxidation of 4-chlorophenol with CuO or Cu2O has been examined using the slurry flow and catalyst packed-bed reactor systems. It is found that Cu2O has a remarkable catalytic activity for the hydrothermal oxidation of 4-chlorophenol compared with those of CuO and Cu-supported TiO2. The conversion of 4-chlorophenol reached nearly 100% at reaction temperatures around 130℃ when Cu2O was used as catalyst, indicating that it is possible to substantially reduce the reaction condition required for the complete decomposition of persistent organochlorine substances by the hydrothermal oxidation. The continuous treatment of 4-chlorophenol has been also conducted using the packed-bed reactor system with Cu2O. The results demonstrated that 4-chlorophenol could be degraded for up to 22 hours without significant loss of the catalytic activity.
