Reutilization of cathode material from spent batteries as a heterogeneous catalyst to remove antibiotics in wastewater via peroxymonosulfate activation

Recycling of valuable secondary source of materials from spent batteries brings great opportunity for recyclers at end-of-life but a challenging issue. Peroxymonosulfate (PMS)-based advanced oxidation has been considered an efficient approach to eliminate refractory antibiotic in wastewater. In this study, a cathode material (CM) recovered from spent lithium-ion batteries (LIBs) was explored to serve as a direct catalyst to activate peroxymonosulfate for the first time. The CM catalyst included 94% LiCoO2 and 6% other substances (e.g. Co3O4) via a facile calcination process. The reactions between PMS and CM for levofloxacin hydrochloride (LFX) decomposition were investigated. Removal efficiency of LFX displayed close correlations with system parameters including CM catalyst dosage, PMS dosage, LFX concentration, pH value and inorganic ions. An optimal removal of 94% was obtained at CM-850 = 0.4 g/L and PMS = 0.5 mM within 60 min, and the first order reaction kinetic rate constant was 0.07597 min−1. Moreover, 32% total organic carbon had been removed after the reaction. In CM catalyst, the varied valence of Co2+/Co3+ underpinned PMS activation, and the SO4− and non-radical 1O2 were of critical significance in LFX degradation. Adjacent methyl in tertiary amine of LFX molecule was the initial cleavage site. Furthermore, the CM catalysts in PMS activation exhibited prominent stability, the degradation efficiency was 80% after four catalytic cycles. Such strategy advances the development of direct recycling of spent batteries for advanced oxidation based on peroxymonosulfate.