Enhanced reductive dechlorination of chlorinated hydrocarbons in groundwater by emulsified zero-valentiron
SUN Ming-lu1,2, DONG Jun1,2, ZHANG Meng-yue1,2, SUN Chen1,2
1. College of New Energy and Environment, Jilin University, Changchun 130021, China; 2. National Local Joint Engineering Laboratory of Petrochemical Pollution Site Control and Remediation Technology, Jilin University, Changchun 130021, China
Abstract：The biological reduction is an alternative for the remediation of chlorinated hydrocarbons polluted groundwater. However, some issues limit its effectiveness, such as long start up time for microbial acclimatization, continuous pH reduction and the accumulation of toxic by-products. Aiming at the limits, emulsified zero-valent iron (EZVI) was prepared by nano-zero-valent iron (NZVI) coated with emulsified oil (EVO) to retard NZVI passivation and continuously provide carbon source for anaerobic microbial dechlorination. The static batch experiments were conducted to study the kinetics of TCE reduction by EZVI and the intermediate metabolites of tetrachloroethylene (PCE) reduction by EZVI. The results showed that EZVI could effectively retard the passivation of NZVI and enhance the reaction activity.The removal process of TCE by EZVI was a first-order reaction and the reaction rate constant kobs=0.182d-1. Reduction of PCE by EZVI can inhibit the accumulation of DCE. On the 10th day, 97.2% PCE was removed by EZVI, which was 68.9% higher than that by adding EVO. In the reaction process, pH and ORP maintained at 6.5-7.5 and -50-10mV, respectively, which provided a beneficial reduction environment for the effective enhancement of the anaerobic biological dechlorination reaction.
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