Supercritical water oxidation of polychlorinated biphenyls using hydrogen peroxide

The efficiencies of hydrogen peroxide and oxygen as oxidants for the destru ction of 3-chlorobiphenyl were compared under supercritical water condition s in the range of 473-723 K at a fixed density of 0.36 g/ml using a batch-r eactor system. The effects of temperature, and oxidant concentration on the destruction of PCBs were also studied. The conversion of hydrogen peroxide was significantly higher than that of oxygen. The highest conversion was o ver 99.999%, and then the concentration of 3-chlorobiphenyl (3-PCB) in the collected effluent is only 0.3 ppb, while the conversion using oxygen was o nly 14.3% under the same conditions. Furthermore, in a flow-reactor system in addition to the batch-reactor system, supercritical water oxidation (SCW O) of polychlorinated biphenyls (PCBs) such as 3-PCB and Kanechlor KC-300 ( KC-300) using hydrogen peroxide was carried out at 30 MPa and 673 K in the range of residence times from 10.7 to 101.7 s. In all runs, over 99% of 3-c hlorobiphenyl was found to be decomposed perfectly by more than stoichiomet ric demand of hydrogen peroxide. The effect of residence times and the conc entration of hydrogen peroxide have further been investigated. (C) 1999 Els evier Science Ltd. AII rights reserved.