LAUSR

The disposal of hazardous waste of any form has become a great concern for the industrial sector due to improved environmental awareness. The increase in usage of hydroprocessing catalysts by petrochemical industries, and lithium-ion batteries (LIBs) in portable electronics and electric vehicles will soon generate a large amount of scrap and create significant environmental problems. Like general electronic wastes, spent catalysts and LIBs are currently discarded in municipal solid waste and disposed of in landfills in the absence of policy and feasible technology to drive alternatives enough policy and feasible technology. Such inactive catalyst materials and spent LIBs exhibit not only hazardous heavy metals but also toxic and carcinogenic chemicals. Besides polluting the environment, these systems (spent catalysts and LIBs) contain valuable metals such as Ni, Mo, Co, Li, Mn, Rh, Pt, and Pd. Therefore, the extraction and recovery of these valuable metals has significant importance. In this review, we have summarized the strategies used to recover valuable (expensive) as well as cheap metals from secondary resources - especially spent catalysts and LIBs. The first section contains the background and sources of LIBs and catalyst scraps with their current recycling status, followed by a brief explanation of metal recovery methods such as pyrometallurgy, hydrometallurgy and biometallurgy. The recent advancements in these methods are critically summarised. Thus, the review provides a guide for the selection of adequate methods for metal recovery and future opportunities for the repurposing of recovered materials.