Direct Hydrothermal Synthesis of Ternary Li-Mn-O Oxide Ion-Sieves.

Spinel-type ternary LiMn2O4 oxide precursor was synthesized by direct hydrothermal synthesis of Mn(NO3)2, LiOH, and H2O2 at 383 K for 8 h, a better technique for controlling the nanocrystalline structure with well-defined pore size distribution and high surface area than the traditional solid state reaction method. The final low-dimensional MnO2 nanorod ion-sieve with a lithium ion selective adsorption property was further prepared by an acid treatment process to completely extract lithium ions from the Li–Mn–O lattice. The effects of hydrothermal reaction conditions on the nanostructure, chemical stability, and ion-exchange property of the LiMn2O4 precursor and MnO2 ion-sieve were systematically examined via powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), and lithium ion selective adsorption measurements. The results show that this new kind of low-dimensional MnO2 nanorod can be used for lithium extraction from aqueous environments, including brine, seawater, and waste water. [ABSTRACT FROM AUTHOR]