Dechlorination mechanism of PCBs by microwave irradiation

Such compounds as chlorinated biphenyl are called polychlorinated biphenyls (PCBs). PCBs had been used in many power apparatuses such as transformers and capacitors because of their thermal stability, chemical stability and good insulating performance. As it was found that PCBs have severe toxicity, the production and the import of them in Japan are nowadays prohibited except the purpose of academic researches, and the disposal and the treatment of them are also restricted strictly. Owing to the difficulty in the decomposition of them, most of them have been stored. In recent years, a new effective processing for PCBs has been developed. With this processing, PCBs can be made harmless by dechlorination of them using microwave (2.45 GHz). Unlike conventional treatments, this new processing hardly produces harmful by-product materials. For designing an efficient reactor, it is expected to establish a real-time method for monitoring the amount of PCBs in solution during degradation process. The authors have tried to clarify the decomposition process of PCBs with such an assumption that the adsorption state of molecular PCBs on the surface of the catalyst might be influenced by the microwave radiation. In this paper, the transient change in the accumulation charge of the PCBs solution with the microwave irradiation is measured by using a Faraday gauge.