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TRICHLOROETHYLENE DEGRADATION BY ZERO-VALENT ZINC IN AQUEOUS SOLUTIONS

We studied the enhanced reactivities of Zn as promoted by bimetallic combinations with Ag, Ni, and Pd. The amount of time required to complete the dechlorination was found to vary from a few hours to many days. The highest efficiency was obtained in the presence of cryo-Zn (ultrafine Zn) particles and palladium promotor.

Important intermediates in the degradative pathways were investigated to further elucidate the dominant pathway and general mechanism. A variety of techniques was employed to analyze the gaseous, aqueous, and solid phase. Ethylene, ethane, and monochlorinated hydrocarbons were identified as the hydrogenation or elimination products. Dehydrochlorination or (-elimination was also evident by acetylene appearance. Other related Cl and C2 compounds were produced in much smaller yields. These results and further issues of interests will be discussed.

Key words: dechlorination, trichloroethylene, dichloroethenes