Abstract:
Chlorinated hydrocarbons are among the most common pollutants at industrial sites and have been detected widespreading in both soil and groundwater. Because of their environmental persistence and toxicities, there is a growing interest in developing new technologies for the removal of chlorinated hydrocarbons in the environment. The degradation of a typical chlorinated hydrocarbon, trichloroethane (TCE) by hydrogen peroxide (H
2O
2) was studied by using an iron-loaded zeolite (Fe-ZSM-5) as heterogeneous catalyst. In the Fe-ZSM-5/H
2O
2 system, the removal rate of TCE (0.9 mmol·L
-1) reached 88% with 0.8 g·L
-1 Fe-ZSM-5 and 10 mmol·L
-1 H
2O
2 at initial pH 7.4 and ambient temperature. And with the increasing of catalyst dosage and H
2O
2 concentration, the removal rate of TCE gradually increased, and the removal rate could reach up to 99%. In addition, initial pH had minor effect on the degradation of TCE. Compared with Fe-ZSM-5, the degradation rate of TCE was only 41% by ZSM-5 without iron loading, and the removal rate decreased when H
2O
2 concentration increased from 6 mmol·L
-1 to 14 mmol·L
-1, while the initial pH had also a minor effect on the removal rate of TCE. The results of free radical quenching experiment show that ·OH played a major role in the degradation of TCE in Fe-ZSM-5/H
2O
2 system, which was largely absent in ZSM-5/H
2O
2 system.