Electro-activation of peroxymonosulfate for degradation of doxycycline using Cu-activated carbon fiber recovered from Cu-containing wastewater

Excessive discharge of copper-containing electroplating wastewater and the widespread misuse of antibiotics pose serious risks to human health and the environment. Herein, an innovative electrochemical closed-loop system was proposed, in which copper-loaded activated carbon fibers (Cu-ACF) were recovered via electrodeposition from Cu-containing wastewater and subsequently employed as cathode to activate peroxymonosulfate (PMS) for doxycycline (DOX) degradation. At an applied potential of −1.1 V, the Cu 2+ deposition capacity reached 729.9 mg⋅g −1 . Copper species were mainly present as Cu 2+ together with Cu 0 /Cu + species on the ACF surface, providing active sites for electron transfer and enhancing PMS activation. Under optimal conditions, more than 95% of DOX was removed within 60 min, exhibiting a pseudo-first-order rate constant about twice that of blank ACF. Cu-ACF 1 also showed good reusability, retaining 85.1% removal efficiency after five cycles. Electrochemical analyses demonstrated that Cu-ACF exhibited enhanced catalytic current response and interfacial activity compared to blank ACF, favoring PMS activation. Multiple reactive oxygen species were identified in the system, with •O 2 − identified as the dominant contributor, while 1 O 2 from a non-radical pathway served as the secondary species. In addition, DOX can be degraded via three pathways, generating 19 intermediate products, most of which exhibit low toxicity. This work provides a sustainable strategy that simultaneously enables copper recovery and efficient antibiotic removal, offering dual benefits for resource recycling and environmental protection.