Electrochemical remediation of polychlorinated biphenyls: Critical review of status, challenges and future prospects

Polychlorinated biphenyls (PCBs) are a major class of persistent organic pollutants (POPs) known for their exceptional chemical stability, hydrophobicity, and resistance to degradation. Their widespread industrial use until the 1980s led to extensive environmental contamination, and their persistence continues to pose ecological and health concerns. Conventional remediation methods such as incineration, photolysis, and microbial degradation often result in incomplete destruction or secondary pollution. Electrochemical remediation presents a sustainable and controllable alternative capable of inducing selective dechlorination and mineralisation through redox transformations at electrode interfaces. This review systematically examines four decades of electrochemical research on PCB degradation, summarising mechanistic insights from both reductive and oxidative pathways. Emphasis is placed on how factors such as electrode composition, supporting electrolyte, mediators, pH, surfactants, and PCB congener structure govern degradation efficiency and selectivity. Despite the long-standing recognition of electrochemical techniques, the number of studies remains limited due to challenges related to PCB solubility, mass transfer, and electrode fouling. Nevertheless, the field offers considerable unexplored potential for optimization through advanced electrode design, coupled processes, and reactor innovation. This review identifies key gaps, highlights mechanistic understanding, and outlines opportunities for developing efficient and scalable electrochemical routes for PCB remediation.