Enhanced electrocatalytic dechlorination by dispersed and moveable activated carbon supported palladium catalyst

In this study, a novel approach was developed for the dechlorination of 2,4-dichlorobenzoic acid (2,4-DCBA) via the combination of the moveable activated carbon (AC) supported palladium (Pd) nanoparticles and nickel (Ni) foam electrode. The morphology and chemical structure of Pd/AC catalyst was investigated by various characterization techniques, including SEM, TEM, EXS-mapping, XRD, and XPS. Pd nanoparticles was successfully loaded and dispersed on the AC, accompanied with the significantly enhanced reactivity. The removal rate of 2,4-DCBA by Ni electrode with moveable Pd/AC catalyst was 222, 25, and 5 folds higher than dispersed AC and Ni electrode system, chemical deposited Pd/Ni electrode, and electrodeposited Pd/Ni electrode, respectively. Compared with the conventional electrocatalytic reductive approach which deposited Pd on the Ni foam electrode, moveable Pd/AC catalyst possesses higher surface area, more atomic H∗ production and more active sites, favored mass transfer, and enhanced reactivity, without the consideration of catalyst loss and deactivation. The effects of Pd:AC mass ratio, constant current, initial solution pH, and electrolyte concentration on the dechlorination of 2,4-DCBA were studied. Generally, high Pd loading, constant current, and acidity favored the dechlorination of 2,4-DCBA, while excessive electrolyte would inhibit the dechlorination of 2,4-DCBA. Good longevity and recyclability of moveable Pd/AC catalyst was confirmed via consecutive experiments. The findings of the present study show that making the catalyst moveable is a promising strategy for electrocatalytic remediation technology.