Synthesis of MnO2 derived from spent lithium-ion batteries via advanced oxidation and its application in VOCs oxidation.

In this work, manganese is selectively and efficiently recovered from spent lithium-ion batteries via advanced oxidation by using potassium permanganate and ozone, and the transition metal-doped α-MnO2 and β-MnO2 are one-step prepared for catalytic oxidation of VOCs. The recovery rate of manganese can be approximately 100% while the recovery efficiency of cobalt, nickel, and lithium is less than 15%, 2%, and 1%, respectively. Compared with pure α-MnO2 and β-MnO2, transition metal-doped α-MnO2 and β-MnO2 exhibit better catalytic performance in toluene and formaldehyde removal attributed to their lower crystallinity, more defects, larger specific surface area, more oxygen vacancies, and better low-temperature redox ability. Besides, the introduction of the appropriate proportion of cobalt or nickel into MnO2 can significantly improve its catalytic activity. Furthermore, the TD/GC-MS result indicates that toluene may be oxidized in the sequence of toluene - benzyl alcohol - benzaldehyde-benzoic acid - acetic acid, 2-cyclohexen-1-one, 4-hydroxy-, cyclopent-4-ene-1,3-dione - carbon dioxide. This method provides a route for the resource utilization of spent LIBs and the synthesis of MnO2.