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Enzyme-electrolytic degradation of dichloromethane: Efficiency, kinetics and mechanism

Author:
Yu, Jianming, Wu, Meng, Tang, Yuwei, Shi, Jiaqi, Hu, Jun, Yu, Zhiliang, Chen, Jianmeng
Source:
Journal of environmental sciences (China) 2019 v.86 pp. 187-194
ISSN:
1001-0742
Subject:
catalytic activity, dechlorination, electrolysis, enzymatic reactions, glutathione, glutathione transferase, methane, methyl chloride, methylene chloride, microbial electrolysis cells, models, pH, pollutants, temperature
Abstract:
Enzymatic electrolysis cell (EEC) has advantages over microbial electrolysis cell (MEC) due to the needless of microbe inoculation and high-efficiency of enzymatic reaction. In this study, an EEC was first applied to achieve the effective degradation of halogenated organic pollutants and dichloromethane (CH2Cl2) was utilized as a model pollutant. The results indicate that the degradation efficiency of CH2Cl2 after 2 hr reaction in the EEC was almost 100%, which was significantly higher than that with enzyme (51.1%) or current (19.0%). The current induced the continuous regeneration of reduced glutathione (GSH), thus CH2Cl2 was degraded under the catalysis of GSH-dependent dehalogenase through stepwise dechlorination, and successively formed monochloromethane (CH3Cl) and methane (CH4). The kinetic result shows that with a current of 15 mA, the maximum specific degradation rate of CH2Cl2 (3.77 × 10−3hr-1) was increased by 5.7 times. The optimum condition for CH2Cl2 dechlorination was also obtained with pH, current and temperature of 7.0, 15 mA and 35°C, respectively. Importantly, this study helps to understand the behavior of enzymes and the fate of halogenated organic pollutants with EEC, providing a possible treatment technology for halogenated organic pollutants.
Agid:
6467300