Preparation of CoO-C catalysts from spent lithium-ion batteries and waste biomass for efficient degradation of ciprofloxacin via peroxymonosulfate activation

The functional utilization of transition metals from spent lithium-ion batteries (LIBs) is an essential upcycling way. Herein, we propose a win–win strategy to recover Li and prepare CoO-C catalysts from spent LIBs and waste biomass, and the CoO-C catalyst is used to activate peroxymonosulfate (PMS) to degrade ciprofloxacin (CIP). The interaction between CoO and carbon endows the CoO-C catalyst with a degradation efficiency of 99.99% within 30 min. Both the radical pathway (SO₄^·- and ^·OH) and the non-radical pathway (surface electron transfer) are involved in the degradation of CIP in the CoO-C/PMS system. The electrostatic potential indicates that the supported carbon improves the electron distribution, showing a particularly high turnover frequency (TOF) value (2.9714 min⁻¹) for CIP. The efficient and stable degradation over a wide range of pH and different aqueous matrices indicates the potential application of CoO-C catalysts. Overall, the pyrolysis reduction upcycles spent LIBs and waste biomass, offering a green way to convert waste to value-added high-performance water remediation catalysts.