Synthesis of Ga3+ doped lithium manganese ion sieve for Li+ extraction and its adsorption thermodynamic behavior

Spinel-type lithium ion sieves exhibit many advantages. We report a gallium ion-doped precursor LiGa0.1Mn1.9O4 prepared by co-precipitation and hydrothermal method. The optimal synthetic parameters were determined by the orthogonal design experiments. The precursor was then transformed into the corresponding ion sieve HGa0.1Mn1.9O4 by pickling. The dissolution loss of Mn3+ for HGMO (4.65%) is less than that of the pristine ion sieve without Ga3+ doping (6.59%), which proves that the doped Ga3+ inhibits the dissolution loss effect. The equilibrium adsorption capacity Qe of HGMO is 25.30 mg∙g−1 and the adsorption curve of HGMO for Li+ fits well with the pseudo-second-order kinetic model, indicating that the adsorption process is chemical adsorption. The adsorption isotherm conforms to the Langmuir model, and the adsorption process is monolayer adsorption. By the analysis of the adsorption enthalpy change (∆H), Gibbs free energy (∆G) and entropy (∆S) change of HGMO at different temperatures, the adsorption process of HGMO for Li+ was confirmed as endothermic and spontaneous.