One-step calcination of Ni/Co/Mn ternary catalysts from spent lithium-ion batteries for iopamidol degradation via peroxymonosulfate activation

The Ni/Co/Mn ternary catalysts were fabricated through a one-step calcination process using the cathode material (CM) derived from spent lithium-ion batteries. The morphological and structural properties of the Ni/Co/Mn catalysts calcined at various temperatures (labeled as CM-450, CM-550 and CM-650) were characterized. CM-650 demonstrated the lowest concentration of metal leaching, excellent stability, and efficient activation performance for peroxymonosulfate (PMS) in the degradation of iopamidol (IPM). The catalytic activity of ternary CM-650 was obvious higher than the respective cathode material. Radical quenching experiments, electron paramagnetic resonance (EPR), and electrochemical characterization analysis indicated that both radical (·OH, SO4•−, ·O2−) and non-radical pathways (1O2, electron transfer) were involved in the CM-650/PMS system. The conversion between Ni(III)/Ni(II) and Co(III) /Co(II) as well as Mn(III)/Mn(II), Mn(IV)/Mn(III) redox couples on the surface of CM-650 facilitated the activation of PMS and a synergistic effect among Ni, Co and Mn existed. Liquid chromatography-mass spectrometry (LC-MS) and density functional theory (DFT) calculations were employed to analyze the degradation intermediates and reaction pathways of IPM. ECOSAR analysis indicated that some intermediates posed certain ecological risks. In summary, the one-step calcination of Ni/Co/Mn ternary catalysts exhibited a sustainable, cost-effective, and environmentally friendly approach for converting waste materials into valuable, high activating-performance materials.