Abstract:

Various polymorphs of MnO₂ were synthesized with a controlled hydrothermal method.Li-Mn-O precursor was prepared by the wet impregnation of a solution of LiOH·H₂O into MnO₂ synthesized，and the final MnO₂ ion-sieve was obtained by acid treatment.The crystalline phase structure and exchangeability of Li⁺were studied with XRD，TEM Li⁺adsorptive isotherm and kinetic measurement.The result showed that reactant concentration had different effects on the growth rate of different MnO^₂ crystal faces.The novel MnO₂ nanowires，mainly about φ 5 nm×400 nm in diameter and length，were found to have a remarkable lithium ion sieve property with monolayer saturation amount of 2.43 mmol·g^-1 and the adsorption rate constant of 2.16×10^-6s^-1 at pH=9.19.The lithium adsorption capacity of MnO₂ ion-sieve increased with the increase of pH value，up to 3.47 mmol·g^-1 at pH=12.5.