Electrostatic-assisted purification and recovery of waste lithium solution to lithium aluminum layered double hydroxide

초록

The escalating demand for lithium (Li), driven by battery applications in electric vehicles, underscores the need for efficient recovery from low-concentration waste Li+ solutions. This study develops high-performance membrane capacitive deionization (MCDI) electrodes by integrating P60 as conductive activated carbon, characterized by a high specific surface area (1752 m2 g−1) and low bulk resistivity (1.344-0.557 Ω sq−1). These properties enable robust electric double-layer formation achieving > 99% lithium recovery from waste solutions containing 69.8 mg L−1 of Li+. Adsorption equilibrium studies reveal a Langmuir isotherm fit, with a maximum adsorption capacity of 7.75 mg g−1 at 1.3 V, demonstrating monolayer coverage. Kinetic studies show current stabilization within 14.5 min for electro-sorption and 5.5 min for desorption in a 200-unit cell configuration. Notably, developed electrode samples suggest not only the effective Li+ recovery but also the purification process of waste Li solution containing Li (69 mg L−1) together with Na (42 mg L−1) and Ca (38 mg L−1). The integrated MCDI-precipitation method concentrates lithium to ∼542 mg L−1, enabling precipitation as Li-Al LDH at a reduced Al/Li molar ratio of 4, with ∼42% less aluminum reagent compared with conventional methods. The process yields a purified effluent (<1 mg L−1 total metal ions) and reduces waste volume to ∼12%. We expect that this eco-friendly approach offers superior efficiency and sustainability for lithium recovery and waste solution purification. © 2025 Elsevier B.V.

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