Enhanced electrocatalytic dechlorination of para-chloronitrobenzene based on Ni/Pd foam electrode

Abstract The electrochemical dechlorination of para -chloronitrobenzene ( p -CNB) was investigated in order to reduce the impact on environment. Based on the sponge-like structure of Ni foam and the catalytic activity of Pd, the Ni/Pd foam electrode exhibited excellent catalytic properties for dechlorination of p -CNB. Electrocatalytic dechlorination performance of Ni/Pd foam electrode for p -CNB was superior to that of other cathodes, such as Ni foam, Ti plates, graphite, and Ti/Pd cathodes. The degradation rate of p -CNB on the Ni/Pd foam electrode is highest among them, and a desirable dechlorination effect can also be obtained. Under optimized conditions of 10 mA cm −2 current density, pH of 7 and Na 2 SO 4 of 50 mM as electrolyte, the removal efficiency of p -CNB (25 mg L −1 ) is more than 99% within 30 min. The process can be described by pseudo-first-order kinetics with the rate constant of 0.147 min −1 , and the AN (aniline) formation efficiency reaches 88.2% within 30 min. In acidic condition, the AN formation efficiency increases to 98.4% within 30 min. The synergistic combination of the current density, acidic condition and lower electrolyte concentration plays an important role in tuning the favor degradation and dechlorination of p -CNB. In addition, among three possible pathways of p -CNB dechlorination proposed, the route from ammoniation to para -chloroaniline ( p -CAN) by dechlorination is regarded as the main pathway.