R & D of PCB Detoxification by Ultra-Violet Irradiation Generated by Poly-Phase AC Glow Discharge

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We investigated experimentally practical use of a detoxification technology of polychloride biphenyls (PCBs) by photo-dechlorination process with use of an originally developed ultraviolet (UV) irradiation source. The PCBs are one of toxic organic-chloride wastes, which are harmful to the earth environment and are stable enough to be hardly decomposed thermally or chemically. The studied method can process PCBs under a moderte (<50℃) temperature and an atmospheric pressure, which is friendly with the environment. The UV light is efficiently emitted from poly-phase ac glow discharges among multiple electrodes in a special multi-pole magnetic field. The light efficiency is high and the power capacity is easily enlarged with a low cost.We got two principal results from the experiments. The one is that UV dechlorination was not effective for a PCB sample which is mixed slightly (<100ppm) in mineral oil. The similar oil has been hold in abundances asa waste oil of huge number of pole transf … More ormers at electric power companies. The dechlorination of PCBs was interrupted by mineral oil itself which absorbs strongly UV light. The other is that UV dechlorination reaction proceeded almost completely even for a highly chlorinated PCB sample, if the UV transmission lenght is well adjusted by a solvent like isopropyl alcohol. The similar sample which is composed of highly chlorinated biphenyls (>70%) and chlorinated benzenes has been hold very much as insulation oil of train's transformers belonging to rail road companies.Sample solutions were contained in two kinds of a quartz tube container with a volume of 1 or 10 litter. The small container was inserted into a small UV light source with a diameter of 10cm and a lenght of 50cm. The larger one was set into a large source with a diameter of 20cm and a length of 70cm. The small light source was generated by a six-phase ac glow discharge in six-pole magnetic field with 6 electrodes at a pressure 0.1 Torr of H2 gas. The large one was by a twelve-phase discharge in twelve-pole field with 12 electrodes. Since the multi-phase discharge current can now continuously without any ac breaking, the light emission is continuously with small temporal fluctuation. Furthermore, since the discharge-plasma is effectively confined without end loss, the light is efficiently emitted with strong intensity.In future, we are going to corroborate with two companies in order to apply our study to practical use. The companies already developed a PCB detoxification pilot plant by using a combined method of UV dechlorination and biological decomposition. Less