title: [Reductive dechlorination of chlorinated hydrocarbons in water by Ag/Fe catalytic reduction system].
abstract: Dechlorination of many kinds of chlorinated hydrocarbons including trichloromethane (CF), tetrachloromethane (CT), 1, 1,1-trichloroethane (1, 1, 1-TCA), 1, 1, 2, 2-tetrachloroethane (1, 1, 2, 2-TeCA), hexachloroethane (HCA), trichloroethylene (TCE), perchloroethylene (PCE) in water by Fe and Ag/Fe were investigated. Results show that the existence of Ag on Fe can enhance the dechlorination rate of chlorinated hydrocarbons. When the surface area concentration of iron is 150 m2 x L(-1), the dechlorination rate constant of CF, CT, 1, 1, 1-TCA, 1, 1, 2, 2-TeCA, HCA are 0.084 h(-1), 2.358 h(-1), 0.417 h(-1), 0.215 h(-1), 1.098 h(-1) by single Fe0, in this condition, no dechlorination of TCE and PCE during 10h, while the dechlorination rate constant of CF, CT, 1, 1, 1-TCA, 1, 1, 2, 2-TeCA, HCA, TCE, PCE are up to 1.850 h(-1), 9.504 h(-1), 1.624 h(-1), 1.778 h(-1), 2.842 h(-1), 0.463 h(-1), 1.251 h(-1) by Ag/Fe. The dechlorination rate constant of CF can increase by the factor of 20. The reaction pathways of chlorinated hydrocarbons with Fe and Ag/Fe were mainly including hydrogenolysis, reductive elimination and dehydrochlorination. The hydrogenolysis is the main reaction pathway for CF, TCE and PCE. The dechlorination pathway of 1, 1, 1-TCA are both hydrogenolysis and dehydrochlorination. Reductive beta elimination to form DCE is the dominant reaction pathway of 1, 1, 2, 2-TeCA, and HCA is via reductive beta elimination to form PCE firstly, then via hydrogenolysis to DCE.
authors.affiliation: State Engineering Research Center for Urban Pollution Control, College of Environmental Science & Engineering, Tongji University, Shanghai 200092, China. wudeli@mail.tongji.edu.cn
authors.forename: De-li
authors.initials: DL
authors.lastname: Wu
authors.forename: Hong-wu
authors.initials: HW
authors.lastname: Wang
authors.forename: Lu-ming
authors.initials: LM
authors.lastname: Ma
mesh_terms: D002251:Carbon Tetrachloride / Q000737:chemistry; D002384:Catalysis; D002713:Chlorine / Q000737:chemistry*; D004980:Ethane / Q000031:analogs & derivatives / Q000737:chemistry; D005296:Ferrous Compounds / Q000737:chemistry*; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D010084:Oxidation-Reduction; D018030:Silver Compounds / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D005296:Ferrous Compounds; D006843:Hydrocarbons, Chlorinated; D018030:Silver Compounds; D014874:Water Pollutants, Chemical; C015530:1,1,2,2-tetrachloroethane; D002713:Chlorine; D002251:Carbon Tetrachloride; D004980:Ethane