Abstract:Fe3O4 was passivated by silica based on Stober method. Lithium manganese oxide grew at silica interface. Li1.6Mn1.6O4@SiO2@Fe3O4 nanometer lithium ion-sieve precursors were produced after aging, filtration, drying, and calcining. SEM and EDX tests show that lithium manganese spinel is relatively uniformly coated on surface of passivated magnetic core. Average particle size of magnetic ion-sieve is 18.6 nm. Equilibrium adsorption capacity of lithium H1.6Mn1.6O4 is 8.78 mg/g, and adsorption capacity of H1.6Mn1.6O4@SiO2@Fe3O4 prepared for this research is 6.01 mg/g in simulated brine. In addition to Mg2 equilibrium adsorption capacity of 5.213 mg/g, adsorption of other ions is 1.756 mg/g below, indicating that adsorption of Li to material has good selectivity. After repeated experiments with magnetic lithium ion sieves for 10 times, equilibrium adsorption capacity of Li is 5.1mg/g with desorption rate of lithium of about 95%. Magnetic lithium ion sieve has good magnetic properties with saturation magnetization of 15.14 emu/g and coercivity of 63.02 G, which can be separated from brine by magnetism separation under the applied magnetic field.