Kinetics of electrochemical dechlorination of 2-chlorobiphenyl on a palladium-modified nickel foam cathode in a basic medium: From batch to continuous reactor operation

A kinetic model for the electrochemical dechlorination of polychlorinated biphenyls (PCBs) will be an important contribution to the design and optimization of a continuous reactor. Initially, the electrocatalytic hydrodechlorination of 2-chlorobiphenyl (2-ClBP) to biphenyl at a palladium-modified nickel foam (Pd/Ni) cathode in a batch reactor was used as a model reaction for a quantitative study of the influences of the operating parameters, including temperature, the initial concentrations of PCBs, current density and the amount of Pd loading, on the apparent reaction rate. The dechlorination was found to follow pseudo first-order kinetics with respect to the 2-ClBP concentration. It was also found that a simple global power law rate equation, with Arrhenius dependency, can be used to describe the correlation between the pseudo first-order reaction rate constants and the reaction conditions. Subsequently, a mathematical model for predicting the performance of reductive dechlorination of 2-ClBP on Pd/Ni electrodes in a continuous stirred tank reactor was constructed, based on the batch-reaction kinetics. The suitability of the model was validated by performing experiments in and out of the range of reaction conditions applied in the batch reactor. The results show that the calculated values are a good fit to the experimental data.