Overcoming catalyst deactivation with in-situ electrochemical regeneration in packed-bed reactors enabling long-lived wastewater purification.

Abstract

Heterogeneous advanced oxidation processes (HG-AOPs) can efficiently remove persistent pollutants but are constrained by catalyst deactivation from polymeric deposits and by energy- and chemical-intensive regeneration. We report a conductive packed-bed reactor that couples continuous treatment with in-situ electrochemical regeneration, maintaining high pollutant removal across diverse contaminants and complex matrices. Upon loss of activity due to catalyst deactivation, applying a mild current with low-cost H₂O₂ restores performance without reactor downtime. Mechanistic analyses show that electrochemical modulation lowers surface lipophobicity and weakens the interaction between polymeric products and the catalyst, enabling their desorption. Meanwhile, electrogenerated ^•OH promotes the coupling of residual phenolic polymers into insoluble aggregates and mineralizes quinoid compounds, recovering interfacial mass and electron transfer. Industrial coking wastewater can be continuously treated using a series-parallel reactor system, which alternates between oxidation and regeneration phases. This approach maintains over 80% total organic carbon removal efficiency for more than 300 hours of operation. Compared with conventional advanced oxidation processes, this strategy reduces operating costs by ~68%, minimizes external chemical inputs, and avoids high-temperature regeneration. The reactor architecture and regeneration logic are scalable, compatible with distributed deployments, and readily retrofittable to existing units, providing a sustainable pathway to extend catalyst lifetimes, lower resource intensity, and advance next-generation oxidation technologies.