Higher degree disposal of hardly decomposed organic halogen compounds for non-toxicity.

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As the organic compounds containing halogens such as PCB are very harmful, environmentally contaminative and hardly decomposable, it is very important to dispose the compounds. The purpose of this study is to decompose the compounds completely. Most difficult work in the process is to convert the halogen to harmless form. Therefore, we selected the molten salts with basic property as the reaction medium. This method has the advantages that are under the atmospheric pressure and the moderated temperatures n addition to strong absorbability of halogens.In this study, the molten salts used were strongly basic KOH-K_2CO_3 or NaOH-Na_2CO_3 mixtures. The sample compounds as the liquids were injected into the molten salts together with the carrier gas which were imitation air, oxygen or nitrogen. The exhaust was analyzed by means of the gas chromatography mass spectrometer (GC/MS). The flow rates of the sample liquid and carrier gas were controlled independently to obtain various flow rates and the concentrations.The experiments were carried out for CCl_4, monochlorobenzene, o-dichlorobenzene, 1,2,3 trichlorobenzene and 4,4' dichlorobiphenyl at the temperatures of 400-700℃. As 1,2,3 trichlorobenzene and 4,4' dichlorobiphenyl are solids in room temperature, they were dissolved into the organic solvent.As the results, higher than 99.998% of the decomposition efficiencies were obtained for all the compounds at 600-700℃. In the case of nitrogen as the carrier gas, some intermediate compounds were found in the exhaust. However, all of them were the compounds excluding the chlorine. It suggests that the chlorine in the compounds was removed effectively even if the compounds were not completely decomposed to H_2O and CO_2. It is very good finding based on the viewpoint to make the harmful compounds harmless. Totally, it is considered that this method is very effective to decompose the harmful organic compounds containing halogen.