With the growing awareness to protect the urban environment and the increasing demand for strategic materials, recycling of postconsumer lithium-ion batteries has become imperative. This study aims to recover lithium, cobalt, nickel, and manganese from a LiNi 0.15 Mn 0.15 Co 0.70 O 2 cathode material of spent lithium-ion batteries of an electric vehicle. By utilizing systematic experimental and theoretical approaches based on the design of experiment and response surface methodology, the best leachant between HCl and H 2 SO 4 + H 2 O 2 and the optimal operating conditions are determined. Leaching with 1.0 M H 2 SO 4 mixed with 0.62 wt % H 2 O 2 at a liquid-to-solid ratio of 25.8 mL g −1 and a temperature of 51 °C for 60 min results in ∼100% recovery of all four metals. After leaching, cobalt, nickel, and manganese are coprecipitated as Ni 0.15 Mn 0.15 Co 0.70 (OH) 2 at pH above 11, while lithium is precipitated as lithium carbonate. These precipitates are mixed and sintered to generate a new cathode material, which is used to make a battery with high electrochemical performance. Valorization of spent lithium-ion batteries from electric vehicles enables conserving natural resources and protecting ecosystems, both of which enable the long-term sustainability of the biosphere while at the same time contributing to the circular economy.
Spent coffee grounds (SCGs) have been extensively investigated as a feedstock to produce fuels, specialty chemicals and materials. Whilst a few reports have used cascade processes to generate several products from SCG, this work takes the novel approach of using integrated subcritical water extraction (SWE) and hydrothermal carbonisation (HTC) to derive three products: a bioactive extract, a protein isolate (SCG PI) and solid fuel. SWE and HTC processes were optimized producing an antioxidant rich extract, with the chlorogenic acid (CGA) content and antioxidant activity determined. The protein content was quantified via total amino acid analysis, giving the first SCG specific elemental nitrogen-to-protein conversion factor of 7.90. HTC was then performed on the residual solids from SWE, the protein extraction and the raw feedstock. This biorefinery approach gave higher quality products than previously reported in single product systems. For example, pretreatment reduced nitrogen in the hydrochar (N = 0.23% wt, HHV = 33.30 MJ/kg) relative to the control (3.03% wt, HHV = 31.31 MJ/kg). Limiting biorefinery processes to the pretreatment and HTC preferentially increased protein content (33.0% vs 16.9% wt) and yield (53.0% vs 23.9%) of the protein isolate, rendering a hydrochar with a higher yield and HHV compared with hydrochar derived following upstream SWE process (33.30 vs 26.92 MJ/kg, 16.3% vs 14.7%, respectively). This work goes towards the complete utilisation of SCGs within a biorefinery, highlighting the potential of subcritical water processing to produce commercially viable products across the value chain.
Ultraviolet-visible spectroscopy is one of the most effective, inexpensive, flexible, and simplest analytical techniques to measure species concentration in the liquid phase.
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