Preparation, adsorption and structure of Ce doped layered manganese ion-sieve based on Li₂MnO₃ spatial structure

With appropriate cerium (Ce) doping, the layered lithium ion-sieve precursor Li_1.37Ce_0.001Mn_1.22O₃ was synthesized using hydrothermal and solid-phase calcination, which exhibited Li/Mn ratio exceeding 1, indicating a high theoretical adsorption capacity. The incorporation of Ce further stabilized the spatial configuration of the layered ion-sieve and controlled the dissolution loss ratio of manganese (Mn) to approximately 0.55%. At 25 °C, with pH of 9 and initial lithium-containing solution concentration of 100 mg/L, the adsorption capacity can reach around 33 mg/g. Despite the presence of interfering ions, it maintained selective adsorption of lithium (Li). The lithium adsorption process by layered lithium ion-sieve adhered to the Langmuir adsorption isotherm model, while the kinetics of adsorption conformed to pseudo-second-order kinetics. This adsorption process was characterized as spontaneous and endothermic, with higher temperatures and concentrations of lithium solutions facilitating both the adsorption process and capacity. It was found that in simulation analysis, compared to the cubic ion-sieve precursor, Li in the layered structure occupied more spatial points, resulting in a more compact stacking and increased bond energy. It alleviated the dissolution loss of Mn during the pickling process. The proximity of Ce resulted in a reduction of the charge on Mn and Li. An appropriate amount of Ce doping will enhance the valence state of Mn; however, excessive Ce doping led to the depletion of electrons from nearby Mn and Li. During pickling process, the Li surrounding Ce in the precursor were preferentially replaced by hydrogen (H) due to their lower charge.