Co/SDS-mediated interfacial regulation of stainless-steel-supported PbO2 anode for cephalexin electrooxidation

A Co- and sodium dodecyl sulfate (SDS)-modified PbO 2 anode (SS/PbO 2 -SDS-Co) was fabricated by coupling Co-related electronic modulation with SDS-assisted geometric surface regulation for cephalexin (CLX) electrooxidation. Co/SDS co-modification produced a compact, refined-grain coating with enhanced relative intensity of the β-PbO 2 (110) diffraction peak and a higher XPS-derived Oads/Olat ratio of 4.49. The modified anode exhibited an oxygen evolution potential of 1.60 V vs. SCE, reduced charge-transfer resistance, and increased double-layer capacitance. Under 15 mA/cm 2 and 0.10 M NaCl, complete parent CLX removal was achieved within 4 min, which was strongly associated with chloride-assisted electrooxidation. The electrode retained 89.6% CLX removal after five cycles, with a measured Pb concentration of 255.4 μg/L in the treated solution. In diluted actual cephalosporin-containing pharmaceutical wastewater, approximately 49% COD removal was achieved under optimized conditions, indicating partial oxidation rather than complete mineralization. Scavenger experiments suggested the involvement of hydroxyl-related oxidants and electrogenerated active chlorine species. UV–Vis analysis and DFT calculations further indicated that the β-lactam N-associated and sulfur-containing regions may be potential regions for electrophilic interaction. These results indicate that Co/SDS-mediated interfacial regulation can improve parent antibiotic removal and partial COD reduction, while the environmental risks associated with chlorinated by-products and residual chlorine require cautious interpretation.