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

TL;DR

A new electrochemical system efficiently removes and detoxifies diclofenac, a harmful pharmaceutical pollutant, using a dual-function cathode and anode setup.

Contribution

A dual-functional electrochemical system combining hydrodechlorination and mineralization for enhanced detoxification of diclofenac.

Findings

The CN@PdNi cathode achieved 98.6% electrocatalytic hydrodechlorination efficiency.

The CN anode enabled 96.8% total organic carbon removal through oxidative mineralization.

Toxicity was reduced by 3–5 Log10 units and mung bean germination improved from 68.7% to 99.8%.

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 Pd0/Ni0 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 Pd0 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 Log10 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.

The online version contains supplementary material available at 10.1038/s41598-025-34272-0.

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