|Budget Amount *help
¥3,900,000 (Direct Cost : ¥3,900,000)
Fiscal Year 1996 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1995 : ¥2,900,000 (Direct Cost : ¥2,900,000)
The Base Catalyzed Decomposition (BCD) process was developed to treat for halogenated semi-volatile organic compounds such as PCBs, and chlorinated dibenzo-p-dioxines. Chlorine atoms bounding to biphenyl are dissociated successively, when PCBs were heate over 290ﾟC with alkalihydroxide and carbonblack catalyst in the liquid paraffine. In order to analyze of the reaction rates and mechanism in the BCD process, 4-chloro-biphenyl (4-MCB) used as a surrogate compound for PCBs was put into the laboratory-scale flask with a heater and a fractional distilllation tube. Reaction products were determined by GC-MS,GC-FID,and UV-HPLC analysis.
Disappearance of 4-MCB was found to be pseudo first-order reaction. Rate of 4-MCB Disappearance were effected by reaction temperature, varieties of alkalihydroxide, amounts of the base, and existence of carbonblack, Biphenyl, two methylbiphenyl, two hydroxybiphenyl, and BBE were determined as final reaction products in the BCD process. These final reaction products suggested that the BCD process involves both radical-mechanism and benzyne-mechanism. Yields of these compounds under various conditions supports that a radical reaction is predominant in this process, but not absolutely. It is suggested that the ionic reaction was occured with increase of added base at only high temperature. However, biphenyl was main products in this reactions. It was found that potassium hydroxide (KOH) is much more effective reagent for the dechlorination of PCBs than the sodium hydroxide (NaOH). Values of activation energy of 4-MCB dechlorinaion under various conditions were ranged from 203 to 262 kJ/mol. These facts suggests that in the BCD process, physical problem like mechanical mixing would be more important as well as chemical reactivities. It was showed that recovered chloride ions in the final reaction products agreeded with chloride atom caliculated from disappeared 4-MCB.