Ultrafine Zinc and Nickel, Palladium, Silver Coated Zinc Particles Used for Reductive Dehalogenation of Chlorinated Ethylenes in Aqueous Solution

Zero-valent zinc metal has been employed for the reductive dehalogenation of chlorinated ethylenes. In order to enhance this environmental remediation chemistry, ultrafine zinc particles and transition metal additives (coatings) have been employed. Indeed, activated zinc (cryozinc) significantly enhanced the reduction/dehalogenation process, especially in the presence of nickel and palladium coatings. These reagents were able to achieve rapid, deep reductive dehalogenation of trichloroethylene, trichloroethane, and dichloroethylenes at room temperature under neutral pH conditions. Highest reactivity was found for ultrafine Zn coated with small amounts of palladium. Products, reaction rates, and possible reaction mechanisms and intermediates are presented.