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

Yu, Jianming, Wu, Meng, Tang, Yuwei, Shi, Jiaqi, Hu, Jun, Yu, Zhiliang, Chen, Jianmeng
Journal of environmental sciences (China) 2019 v.86 pp. 187-194
catalytic activity, dechlorination, electrolysis, enzymatic reactions, glutathione, glutathione transferase, methane, methyl chloride, methylene chloride, microbial electrolysis cells, models, pH, pollutants, temperature
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.