Sustainable electrocatalytic hydrodechlorination of chlorinated aromatic acids in groundwater-saturated porous media using an optimized Ru-TiO2 cathode.

Abstract

Electrocatalytic hydrodechlorination (ECH) offers a reagent-free approach for groundwater remediation, but its application in porous media is constrained by uncertain reaction pathways and transport limitations. Here, a low-loading Ru-TiO2 cathode was developed for the removal of 2,4-dichlorobenzoic acid (2,4-DCBA) under batch and flow-through conditions. The cathode achieved 98% removal with a kobs of 0.0160 min-1. Combined electrochemical, spectroscopic, product, and computational results indicate that interfacial electron transfer and adsorbed-hydrogen-mediated processes may coexist during C-Cl cleavage, while surface hydrogen also participates in subsequent hydrogenation. In porous media, 2,4-DCBA removal reached 85-87% over 16 h. Moderate flow improved transport reaction matching, whereas further acceleration produced diminishing kinetic gains because of shortened residence time. Treatment reduced phytotoxicity. One factor TEA/LCA sensitivity analyses identified electricity price, current utilization, grid carbon intensity, and electrolyte management as the principal scale-up variables. These results demonstrate the potential of Ru-TiO2 catalyzed ECH for groundwater remediation.