Kazuyoshi Matsunaga

Superoxide radical-induced degradation of polychlorobiphenyls and chlordanes at low temperature

Polychlorobiphenyls (PCBs), have unique physical and chemical properties. It has been found that commercial PCBs have also contained polychlorinated dibenzofuranes (PCDFs) formed under pyrolytic conditions. Disposal of hazardous PCBs, therefore, has resulted in considerable environmental problems because of their extreme resistance to degradation. This paper presents the results of the chemical degradation studies of PCBs and chlordanes in the presence of pyridine, a chain transfer agent using superoxide ion (O{sub 2}{sup {minus}}) produced by the reaction of hydrogen peroxide and sodium metaperiodate at the low temperature (60-75% C). In this degradation method pyridine, the chain transfer agent with the much lower value of the chain transfer constant, was used so as to prolong the life span of O{sub 2}{sup {minus}} and/or the induced PCBs radical. The radical degradation of PCBs was finally promoted.

Biomimetic chemical degradation of polychlorobiphenyls below 100°C

Abstract PCBs were rapidly degraded by hydroxy radicals formed in the biomimetic degradation systems of superoxide, ferric chloride, and hydrogen peroxide at high concentrations below 100°C. The degradation rates of Kanechlor KC 300, KC 400, KC 500 and KC 600 were 95.4%, 89.1%, 59.9% and 47.9%, respectively. The generation of carbon dioxide gas was recognized and chloride ion showed 89.9 – 102.7% of the theoretical yield in the degradation of KC 300, KC 400 and KC 500.