Degradation Kinetics of Dichlorophenols During Electrochemical Hydrodechlorination Using Palladium/Polypyrrole/Foam Nickel Electrode

Understanding the kinetics during electrochemical hydrodechlorination was of great importance to the design of treatment process. In this study, the six isomers of dichlorophenol were subjected to electrochemical hydrodechlorination using homemade palladium/polypyrrole/foam nickel electrode. Under the conditions of dechlorination current is 5 mA, temperature is 25 °C, initial concentration of pollutants is 0.5 mmol L–1, electrochemical dechlorination time is 120 min, the dechlorination processes of 2,3-dichlorophenol (2,3-DCP), 2,4-dichlorophenol (2,4-DCP), 2,5-dichlorophenol (2,5-DCP), 2,6-dichlorophenol (2,6-DCP), 3,4-dichlorophenol (3,4-DCP) and 3,5-dichlorophenol (3,5-DCP) were compared. The degradation of dichlorophenol reaction followed pseudo-first-order kinetics. During the electrolysis process, the products of six DCP (dichlorophenol) isomers dechlorination are mainly phenol, a small amount of monochlorophenol produced at the same time. The classification kinetics of six kinds of DCP (dichlorophenol) was studied according to the dechlorination path. Then the reaction rate constants of different reaction stages were obtained. Besides, we speculated that the degradation rates of six DCP isomers were affected by pK a and molecular structure.