Efficient recovery of lithium from spent lithium-ion battery raffinate by Mn and Al-based adsorbents: pretreatment, adsorption mechanism, and performance comparison

As a strong wave of retired lithium-ion battery approaches, lithium extraction from spent lithium-ion battery raffinate (SLR) becomes increasingly critical for environmental protection and for sustainable lithium supply. To understand the factors that affect maximum recovery of lithium from SLR, the organic and inorganic components of SLR were initially determined. The organic matter content (up to 760.5 mg/L) seriously impacted the recovery rate of lithium. Therefore, SLR was managed with a series of pretreatment techniques, including coagulation, biochar aerogel adsorption, and ultrafiltration, achieving more than 84.3% removal of organic substances. H1.33Mn1.67O4 and Li/Al layered double hydroxides adsorbents were then synthesized by solid state reaction method and hydrothermal method, respectively, granulated into spheres with a PVC skeleton, and applied to recycle lithium from pretreated SLR in a fixed bed adsorption column. The results indicated that both Mn and Albased adsorbents exhibited rapid adsorption kinetics, reaching saturation within 2 h. The Mn-based adsorbent exhibited superior adsorption selectivity for Li+ and higher Li+/Na+ separation factor (αLNia) compared to Albased adsorbent, with partition coefficients and αLNia values equal to 6.62 mL/g, 8.79 for the former material, and 4.92 mL/g, 8.17 for the latter. On the other hand, the Al-based adsorbent displayed better stability with negligible Al loss, while Mn loss from the related adsorbent was less than 0.2% in every adsorption–desorption cycle. Notably, both adsorbents demonstrated excellent reusability with their adsorption capacity maintained after twenty adsorption–desorption cycles.