Synthesis and adsorption properties of metal oxide-coated lithium ion-sieve from salt lake brine

The Mn-based Li1.6Mn1.6O4 ion sieve is among the most effective lithium adsorbents due to its high lithium-ion adsorption capacity and selectivity for Li-ions. However, the inherent disadvantages of manganese dissolution and low structural stability prevent its industrial application. In this study, a series of Li1.6Mn1.6O4@R were synthesized by the low temperature solid phase hydrothermal method that exhibit highly anti-dissolution properties for the lithium adsorption from brine water. The LMO-L, LMO-LM, and LMO-M adsorbents show great adsorption capacities of 46.0 mg g-1, 43.0 mg g-1, and 38.0 mg g-1 compared to the 42.3 mg g-1 for the pristine adsorbent. After 20 cycles the dissolution loss of Mn was 0.06 % of LMO-L adsorbents. This improvement in adsorption properties is attributed to the stabilized layered structure due to the evolution of oxygen during the coating reaction, and the inhibition of the interfacial side reactions between the solution and the adsorbent by metal oxide coating. X-ray diffraction, and X-ray photoelectron spectroscopy analysis indicate the formation of Li2MnO3 on the material surface, which can increase tetravalent manganese on the surface. Furthermore, our work may provide new insights for the design of efficient Mn-based adsorbents with high stability for water treatment applications.