Sustainably recycling spent lithium-ion batteries to prepare magnetically separable cobalt ferrite for catalytic degradation of bisphenol A via peroxymonosulfate activation.

A selective separation-recovery process based on tuning organic acid was proposed to the resource recycling of spent lithium-ion batteries (LIBs) for the first time. The low-cost preparation of CoFe2O4, reuse of waste acid and recovery of Li can be realized in this process, simultaneously. Li and Co in spent LIBs can be leached efficiently using citric acid as a leaching agent, and separated effectively from leaching solution by tuning oxalic acid content. The results from the characterizations of the prepared CoFe2O4 (CoFe2O4-LIBs) show that it possesses higher ratio of Co(II)/Co(III) and Fe(II)/Fe(III), larger surface specific area and more number of acid sites in comparison with pure CoFe2O4. Besides, CoFe2O4-LIBs was used to activate peroxymonosulfate (PMS) for the degradation of bisphenol A (BPA). Interestingly, its degradation performance is superior to that of pure CoFe2O4 and the related Co-based catalysts. The excellent degradation performance can be maintained in presence of inorganic ions (e.g., Cl-, HCO3-, H2PO4- and NO3-) with high concentration or humic acid. Moreover, surface-bound SO4∙- is considered as the main reactive species for the degradation of BPA. More importantly, CoFe2O4-LIBs can be readily recycled by using an external magnet and own superior ability of regeneration.