Integrated electrochemical dechlorination and mineralization of diclofenac using CN@PdNi cathode and CN anode for enhanced detoxification

Abstract

Abstract Chlorinated pharmaceuticals like diclofenac (DCF) pose persistent environmental risks due to their bioaccumulation and toxicity, necessitating advanced remediation strategies. Herein, an integrated electrochemical system was developed, combining a self-nitrogen-doped carbon nitride (CN)-supported PdNi (CN@PdNi) cathode for electrocatalytic hydrodechlorination (ECH) with a CN anode for oxidative mineralization in a single, sequential process. The CN@PdNi cathode achieved 98.6% ECH efficiency, selectively cleaving C–Cl bonds to mitigate toxicity, which is attributed to its structural merits, including a well-dispersed, albeit partially clustered, nanoparticle distribution, metallic Pd/Ni phases, predominant Pd 0 /Ni 0 states, and enhanced porosity. Subsequent CN anodic oxidation enabled 96.8% total organic carbon (TOC) removal, ensuring near-complete mineralization. Mechanistic studies via Electron paramagnetic resonance (EPR), quenching, LSV, and Tafel slopes revealed atomic hydrogen (*H) generated at Pd 0 sites as the primary reactive species, augmented by electron transfer. The system exhibited robust performance across varied conditions and exceptional stability (< 1% efficiency loss over 11 consecutive cycles). Toxicity assessments showed 3–5 Log 10 unit reductions (ECOSAR) and mung bean germination rates improving from 68.7 to 99.8%. This dual-functional detoxification-mineralization strategy overcomes the limitations of single-step processes and offers a scalable, sustainable solution for efficient remediation of halogenated pollutants.