High-efficiency Dechlorination of Waste by Selective Injection of Microwave Energy into Chemical Bonding between Chlorine and Hydrocarbon

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In this research work, dechlorination of organochlorine compound in waste by using microwave was discussed, as selective excitation of organochlorine by microwave was prospective. Here, Polyvinyl chloride(PVC) was used as sample of organochlorine compound. To obtain its thermal decomposition property, thermogravimetric analysis was carried out. From the results of the analysis, it was found that the thermal decomposition reaction was two-step and the first step took place in the range 483-573 K. It is consider that the first step is mainly caused by dechlorination reaction.Difference between dechlorination properties of PVC with microwave irradiation and with conventional heating was investigated. Dechlorination ratio was measured under several constant temperatures hi the range 463-493 K. It was indicated that both reaction rate and ratio of dechlorination with microwave was greater than those with conventional heating in the range 463-483 K.For uniform microwave irradiation of PVC, fluidized bed reactor using glass beads which had microwave transparency was applied to test equipment. The effect of degree of polymerization, initial reactor temperature, irradiation intensity of microwave and gas velocity on dechlorination ratio and temperature profile of bed was investigated. When the initial reactor temperature was less than 334 K, dechlorination reaction was not confirmed. That is the reason why the dielectric loss of PVC at the lower temperature is too small to absorb microwave energy. On the contrary, rapid rise of temperature in bed and dechlorination reaction was observed over 450 K when initial temperature was more than 334 K. The smaller degree of polymerization of PVC was, the higher dechlorination ratio was observed at 600 W of microwave. However, the dechlorination ratio was independent of the degree of polymerization under condition of 800 W.