Electrochemical reductive dechlorination of 2,4-dichlorophenoxyacetic acid using a palladium/nickel foam electrode

The electrochemical reductive dechlorination of 2,4-dichlorophenoxyacetic acid (2,4-D) in an aqueous solution was investigated at ambient temperature using a palladium/nickel foam (Pd/Ni foam) electrode in batch mode experiments. The catalytic electrode prepared using the standard chemical deposition method was further characterized using X-ray diffraction and scanning electron microscopy. It was observed that the reaction followed a pseudo-first-order kinetics model, the magnetic agitator-supported system could achieve 87% removal of 2,4-D within 4 h, which is 16% higher than the efficiency obtained under a nitrogen atmosphere. No organic intermediates other than phenoxyacetic (PA), o-chlorophenoxyacetic acid (o-CPA) and p-chlorophenoxyacetic acid (p-CPA) were observed to be generated during the reaction. The dechlorination efficiency depended on several factors including the current density, the palladium loading and the initial concentrations of the supporting NaCl electrolyte and the 2,4-D. The palladium loading and the NaCl concentration had a greater effect on the dechlorination kinetics of 2,4-D. Furthermore, the efficiencies of dechlorination and PA formation could be improved by optimizing the reaction system by modifying the ventilation conditions.