Separation or Concentration: Conventional and Selective Electrodialysis for Treating Spodumene Leachate

Growing lithium demand necessitates efficient extraction as current chemical purification and evaporation are energy-heavy and complex. This study explores membrane-based alternatives, conventional electrodialysis (ED), and selective electrodialysis (SED), for separating and concentrating lithium sulfate from the acidic spodumene leachate. Using monovalent-selective cation exchange membranes (CXP-S), SED was evaluated under varying temperatures, solution volume ratios, membrane types, and electrode rinse solutions. The SED process with acid-leaking anion exchange membranes successfully inhibits water splitting in the dilute solution and enhances lithium/impurity cation selectivity, achieving a 98.21% recovery of lithium sulfate with high purity. ED with high-flux cation exchange membranes at 60 °C yields a 2-fold increase in lithium concentration, cutting 63.30% of evaporation energy input. Selectivity analysis confirms SED’s superiority for impurity removal and efficiency of ED for Li+ enrichment. The work demonstrates two functionality aspects, separation and concentration, of membrane-based extraction technology toward sustainable lithium extraction.