Synthesis of Porous Lithium Ion Sieve with High Purity for Li+ Adsorption

With the depletion of solid lithium ore, extracting lithium from salt lake brine has become a critical focus for future endeavors. A four-step method was used to synthesize high-purity H1.6Mn1.6O4 for extracting Li+. Porous cubic Mn2O3 was hydrothermally synthesized with carbon spheres and surfactants as templates. Then, it was converted to LiMnO2 by calcining with Li2CO3. After roasting and acid pickling, H1.6Mn1.6O4 was successfully synthesized. The impacts of calcination temperature, Li/Mn molar ratio and glucose addition on LiMnO2 composition, loss percentage of dissolved Mn in precursor, and the adsorption characteristics of the lithium ion sieve were studied. Glucose inhibited the formation of LiMn2O4 and promoted the formation of pure LiMnO2. The resulting precursor without impurities showed porous structure. After acid pickling, H1.6Mn1.6O4 showed a high-adsorption performance and excellent cycle performance. After five cycles, adsorption capacity remained above 30 mg/g, and the loss percentage of dissolved Mn stabilized at about 1%. The Li+–H+ exchange conformed to pseudo-second-order adsorption dynamics and the Langmuir adsorption isotherm equation, indicating that the adsorption process can be classified as monolayer chemical adsorption.