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In this work, cathode materials of spent lithium-ion ternary batteries are recovered and used as metal precursor to prepare multi-metal oxides MnOx(SY) and GdMnO3(SY) via combustion method and sol–gel method, respectively. Furthermore, a series of MnOx(SY)-n and GdMnO3(SY)-n (n = 0.05, 0.10, 1.00, 4.00, n represents the dilute HNO3 concentration) catalysts are fabricated by acid treatment of MnOx(SY) and GdMnO3(SY) samples and catalytic activities of oxygenated VOCs oxidation over all the prepared catalysts are investigated. Catalytic evaluation results show that acid-treated MnOx(SY)-0.10 and GdMnO3(SY)-0.05 samples perform the optimum VOCs removal efficiency respectively, which may be attributed to their obvious enhancement of physicochemical properties. In detail, MnOx(SY)-0.10 and GdMnO3(SY)-0.05 samples exhibit the larger specific surface area, bigger amount of surface high-valence metal ions (Mn4+, Co3+, Ni3+), more abundant adsorbed oxygen species and better low-temperature reducibility, which can play a crucial role in the significant improvement of VOCs oxidation. In situ DRIFTS results imply that the possible main intermediates are -OCO, -COO and -C-O species produced during VOCs oxidation. Possible by-products are further determined via TD/GC–MS analysis.

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.

Faced with a large amount of spent lithium-ions batteries from new energy vehicles and portable electronic devices such as personal computers and mobile phones. If they are not treated properly, they would not only result in serious environmental pollution but also lead to the loss of valuable resources like Co and Li. At present, most of researchers mainly focused on the metal recovery via hydrometallurgical and pyrometallurgical method. In this work, manganese-based metal oxides (MnOx(SY), MnOx(MS)) and cobalt-based oxides (CoOx(GS)) are synthesized using manganese and cobalt-based metals recovered from spent ternary, manganate and cobaltate lithium-ion batteries as a precursor, respectively. A series of supported multi-metal oxides were prepared by supporting 10% (wt) of MnOx(SY), MnOx(MS) and CoOx(GS) on CeO2 with different morphologies via impregnation method. The catalytic activities of the metal oxides during the oxidation of 2-ethoxyethyl acetate are investigated. The results obtained show that MnOx(MS)/CeO2-C, MnOx(SY)/CeO2-C and CoOx(GS)/CeO2-P have better catalytic performances due to their excellent physicochemical properties compared to the MnOx(SY), MnOx(MS), CoOx(GS), CeO2-R, CeO2-P, CeO2-C, MnOx(MS)/CeO2-R, MnOx(MS)/CeO2-P, MnOx(SY)/CeO2-R, MnOx(SY)/CeO2-P, CoOx(GS)/CeO2-R, CoOx(GS)/CeO2-C. In-situ diffuse reflectance infrared fourier transform spectroscopy results prove that gaseous O2 plays a vital role in facilitating the complete oxidation of intermediates such as ‒C˭O, ‒COO, ‒C‒O‒C, ‒C‒O into CO2 during 2-ethoxyethyl acetate oxidation. Furthermore, thermal desorption/gas chromatography-mass spectrometer results show that the main by-products obtained during 2-ethoxyethyl acetate oxidation are ethanol,2-methoxy-; ethanol, 2-methoxy-, acetate and acetic acid.

In order to avoid the discharge of deplating wastewater with high concentration of NO3−, an environmental friendly process, consisting of precipitation, electrodeposition and oxidation, is developed in this research for the treatment of real high acidic deplating wastewater containing Ag+, Cu2+, NO3− and chemical oxygen demand (COD). The wastewater is treated by precipitation to remove Ag+, electrodeposition to remove Cu2+, oxidation to reduce COD successively and then reused for deplating plastic plated parts. In precipitation process, 99.9% Ag+ in wastewater is precipitated by HCl and silver metal is then recovered through the replacement of AgCl by iron powder. Because of the high conductivity, Cu2+ in wastewater is then separated and recovered as copper metal on cathode through electrodeposition. The effect of electrodeposition parameters including cathode material, current density, electrode distance, reaction temperature and Cu2+ initial concentration is investigated. Up to 89.3% Cu2+ can be recovered in 80 min at the optimal condition. Finally, the COD is removed from 1360 mg L−1 to 378 mg L−1 in subsequent H2O2 oxidation process to ensure the reuse of water. Because the valuable Ag and Cu metals are recovered and the COD is removed, the wastewater can be reused as deplating solution. The estimated profit of this precipitation-electrodeposition-oxidation process reveals its practical feasibility. Furthermore, the process realizes the cleaner production of the deplating technology because it avoids the discharge of unmanageable wastewater with high NO3− concentration. More importantly, the process can also be improved to treat similar wastewater.