Recycling of waste power lithium-ion batteries to prepare nickel/cobalt/manganese-containing catalysts with inter-valence cobalt/manganese synergistic effect for peroxymonosulfate activation

Developing a high-efficiency peroxymonosulfate (PMS) activator is of great significance for the elimination and mineralization of organic contaminants. Herein, a catalyst (LiNi0.5Co0.2Mn0.3O2, NCM) was constructed using the cathode scrap of spent lithium-ion battery (LIB) for activation of PMS to remove Rhodamine B (RhB). The excellent catalytic capacity of NCM-650 was observed, as RhB was completely removed after 25 min. The NCM-650/PMS process could function effectively over a broad pH scope with favorable reusability and adaptability. The non-radical channels (singlet oxygen and mediated charge transfer) played a dominant role in the removal of RhB. Several reactive radical species (sulfate radicals, hydroxyl radicals and superoxide radicals) also facilitated the degradation of RhB, where the Co2+ and Mn4+ on the surface served as active sites to activate PMS. The synergistic effect of inter-valence cobalt and manganese in the catalyst was the predominant medium during the whole reaction process. According to the intermediates identified by High performance liquid chromatograph-mass spectrometry (HPLC-MS) and the analysis of density function theory (DFT) calculations, N-de-ethylation, chromophore cleavage, ring opening, and mineralization were regarded as the primary decomposition pathways. This research provided a novel perspective on the potential application of waste LIBs for the effective activation of PMS.