Improving the adsorption kinetics of Li1.6Mn1.6O4-type adsorbents via synergistic Na and S doping

Li 1.6 Mn 1.6 O 4 -type adsorbents show significant promise for lithium resource extraction from complex saline lakes due to their exceptional selectivity and high theoretical adsorption capacity of 72.3 mg g −1 . However, their practical application is markedly constrained by rapid manganese dissolution during elution with dilute HCl, primarily attributed to Jahn-Teller effect-induced Mn O structural distortion. To address this limitation, a synergistic S 2− /Na + co-doping strategy was employed: Na + stabilizes the spinel structure via Na O bond formation, while S 2− doping enhances charge density. In situ XRD analysis elucidated the structural evolution of the doped material. Experimental results demonstrate that H 1.6 Mn 1.6 O 4 modified with 1 % Na 2 S achieves an adsorption capacity of 39.6 mg g −1 in 300 ppm LiOH solution, with manganese dissolution loss below 2 %, and attains a single-pass lithium extraction efficiency of 99.5 % from oilfield brine containing 100 ppm Li + . Furthermore, the influence of Na + concentration on Li + adsorption selectivity was investigated for the first time, and the underlying mechanism was summarized. This finding is highly significant for efficient lithium extraction from various brines.