Synthesis and properties of Li1.6Mn1.6O4 and its adsorption application

Li1.6Mn1.6O4 was prepared by calcinating orthorhombic LiMnO2 at 410 °C, which was synthesized using a hydrothermal reaction with LiOH and Mn2O3 as the starting reagents. After the Li1.6Mn1.6O4 had been leached with diluted hydrochloric acid, an ion-sieve for lithium (H1.6Mn1.6O4) was obtained. The pickling reaction reached balance quickly, the ratio of extracted lithium was above 90% and the loss ratio of dissolved Mn was under 2.5%. Physical analysis showed that the basic microstructure and surface topography of the materials remained unchanged in the process of pickling and adsorption. The chemical stability of the materials was sufficiently high. The adsorption capacity rose sharply when the pH value was greater than 11; a buffer system was essential to increase the adsorption capacity in weak acidic solution. The adsorption reaction could reach balance quickly in brine because of an increase in temperature; the maximum uptake of lithium from brine was 27.15 mg/g at 50 °C. Dissolved Mn did not affect the adsorption capacity. The adsorption rate of lithium from brine was over 99% under certain conditions in brine. Circulation tests showed that the adsorption capacity decreased as the number of cycles increased. The adsorption and desorption capacity were still more than 20 mg/g after 10 cycles. Larger separation coefficients indicated that high concentrations of Mg2+, Na+, and K+ in brine had a slight adverse effect on lithium recovery using an ion-sieve, and the final lithium carbonate of reagent grade was obtained by a series of steps.