Electron-enriched boronized nickel foam electrode for enhanced electrochemical sulfite activation and water purification.

Electrochemical sulfite (S(IV)) activation is a promising advanced oxidation approach for water purification, yet its efficiency is often limited by sluggish interfacial activation and pronounced mass-transfer limitations. Herein, we develop a flow-through electrochemical system using a boronized nickel foam (B-NF) electrode for efficient tetracycline (TC) degradation. The optimized E/B-NF/S(IV) system achieves a pseudo-first-order rate constant of 3.6 min-1, 7.5 times higher than that of pristine NF. Surface boronization enhances the electron density of Ni, lowers the work function, and generates localized electric fields, thereby promoting charge transfer from Ni to S(IV) and facilitating the generation of hydroxyl (HO•) and sulfate (SO4•⁻) radicals. Computational fluid dynamics (CFD) simulations reveal that the flow-through configuration alleviate mass transfer limitations by thinning the diffusion layer. The system demonstrates strong resistance to matrix interferences and maintains high degradation efficiency in real water samples. Life cycle assessment (LCA) further confirms the environmental feasibility and practical potential of the E/B-NF/S(IV) system. This work highlights the synergistic effects of surface electronic modulation and flow-through reactor design as a scalable and efficient approach for electrochemical S(IV) activation in water treatment.