E‐waste generated from end‐of‐life spent lithium‐ion batteries (LIBs) is increasing at a rapid rate owing to the increasing consumption of these batteries in portable electronics, electric vehicles, and renewable energy storage worldwide. On the one hand, landfilling and incinerating LIBs e‐waste poses environmental and safety concerns owing to their constituent materials. On the other hand, scarcity of metal resources used in manufacturing LIBs and potential value creation through the recovery of these metal resources from spent LIBs has triggered increased interest in recycling spent LIBs from e‐waste. State of the art recycling of spent LIBs involving pyrometallurgy and hydrometallurgy processes generates considerable unwanted environmental concerns. Hence, alternative innovative approaches toward the green recycling process of spent LIBs are essential to tackle large volumes of spent LIBs in an environmentally friendly way. Such evolving techniques for spent LIBs recycling based on green approaches, including bioleaching, waste for waste approach, and electrodeposition, are discussed here. Furthermore, the ways to regenerate strategic metals post leaching, efficiently reprocess extracted high‐value materials, and reuse them in applications including electrode materials for new LIBs. The concept of “circular economy” is highlighted through closed‐loop recycling of spent LIBs achieved through green‐sustainable approaches.

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The peroxidase enzyme from the plants Ipomea palmata (1.003 IU/g of leaf) and Saccharum spontaneum (3.6 IU/g of leaf) can be used as an alternative to the commercial source of horseradish and soybean peroxidase enzyme for the decolorization of textile dyes, mainly azo dyes. Eight textiles dyes currently used by the industry and seven other dyes were selected for decolorization studies at 25-200 mg/L levels using these plant enzymes. The enzymes were purified prior to use by ammonium sulfate precipitation, and ion exchange and gel permeation chromatographic techniques. Peroxidase of S. spontaneum leaf (specific activity of 0.23 IU/mg) could completely degrade Supranol Green and Procion Green HE-4BD (100%) dyes within 1 h, whereas Direct Blue, Procion Brilliant Blue H-7G and Chrysoidine were degraded >70% in 1 h. Peroxidase of Ipomea (I. palmata leaf; specific activity of 0.827 U/mg) degraded 50 mg/L of the dyes Methyl Orange (26%), Crystal Violet (36%), and Supranol Green (68%) in 2-4 h and Brilliant Green (54%), Direct Blue (15%), and Chrysoidine (44%) at the 25 mg/L level in 1 to 2 h of treatment. The Saccharum peroxidase was immobilized on a hydrophobic matrix. Four textile dyes, Procion Navy Blue HER, Procion Brilliant Blue H-7G, Procion Green HE-4BD, and Supranol Green, at an initial concentration of 50 mg/L were completely degraded within 8 h by the enzyme immobilized on the modified polyethylene matrix. The immobilized enzyme was used in a batch reactor for the degradation of Procion Green HE-4BD and the reusability was studied for 15 cycles, and the half-life was found to be 60 h.

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Lithium-ion batteries (LIBs) are extensively used for power storage in most gadgets, electric vehicles (EV), and energy storage devices. Spent LIBs are an excellent source of metals, which can be recycled and reused in new batteries to reduce environmental impacts. Our current study reports bioleaching-mediated metal recovery from spent nickel-, manganese-, cobalt (NMC)-based LIBs at a high solid content, using an autotrophic bacterium Acidithiobacillus ferrooxidans. Inductively coupled plasma–optical emission spectrometry (ICP-OES) analysis showed recoveries of 90% Ni, 92% Mn, 82% Co, and 89% Li from spent LIBs in 72 h at a solid content of 100 g/L. The X-ray diffraction (XRD) and scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX) analyses of the LIB powder before and after bioleaching confirmed that most of the metals leached out from the batteries. A high leaching efficiency was achieved by elevated concentrations of H2SO4 and ferric ion in the A. ferrooxidans culture as well as replenished bacterial culture for three cycles during the bioleaching. The bioleaching process reported here can be used to efficiently extract metals from spent EV batteries in an eco-friendly manner.