摘要
研究了水体中的三氯甲烷(CF)、四氯化碳(CT)、1,1,1-三氯乙烷(1,1,1-TCA)、1,1,2,2-四氯乙烷(1,1,2,2-TeCA)、六氯乙烷(HCA)、三氯乙烯(TCE)、四氯乙烯(PCE)在Ag/Fe以及Fe0还原体系中的还原脱氯反应.结果表明,Ag的加入会明显提高氯代烃的还原脱氯速率,铁表面积浓度为150 m2.L-1时,如果单独使用Fe0,CF、CT、1,1,1-TCA、1,1,2,2-TeCA、HCA的还原脱氯反应速率常数分别为0.084 h-1、2.358 h-1、0.417 h-1、0.215 h-1、1.098 h-1,TCE、PCE在10 h之内没有检测到脱氯反应;而当Ag/Fe质量比为0.1%时,CF、CT、1,1,1-TCA、1,1,2,2-TeCA、HCA、TCE、PCE的反应速率常数可以达到1.850h-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,CF的反应速率常数能提高近20倍.水体中氯代烃在Ag/Fe催化还原体系中的脱氯途径主要有氢解、还原消除和脱氯化氢3种,对于CF、TCE、PCE,主要脱氯方式为逐级氢解,而1,1,1-TCA是逐级氢解和脱氯化氢2种方式,1,1,2,2-TeCA则主要经过还原β消除,脱除2个Cl-形成二氯乙烯(DCE),HCA则是首先经过还原β消除形成PCE,继而发生逐级氢解脱氯反应.
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 m^2·L^-1, the dechlorination rate constant of CF, CT, 1,1,1-TCA, 1,1,2,2-TeCA, HCA are 0.084h^-1, 2.358 h^-1, 0.417 h^-1, 0.215 h^-1, 1.098 h^-1 by single Fe^0, 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 β elimination to form I）CE is the dominant reaction pathway of 1,1,2,2-TeCA, and HCA is via reductive β elimination to form PCE firstly, then via hydrogenolysis to DCE.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2006年第9期1802-1807,共6页
Environmental Science
基金
国家高技术研究发展计划(863)项目(2002AA601270)
关键词
氯代烃
还原脱氯
催化还原
Ag/Fe催化还原体系
chlorinated hydrocarbons
reductive dechlorination
catalytic reduction
Ag/Fe catalytic reduction system
