LiMn2O4 spinel direct synthesis and lithium ion selective adsorption

The cubic phase LiMn2O4 spinel is synthesized via a directly soft chemistry method via hydrothermal reaction of Mn(NO3)2, LiOH and H2O2 at 383 K for 5–10 h, more favorable to control the nanocrystalline structure with well-defined pore-size distribution and high surface area than traditional solid-phase reaction at high temperature. Further, the 1D MnO2 nanorod ion-sieves with lithium ion selective adsorption property is prepared by the acid treatment process to completely extract lithium ions from the LiMn2O4 lattice. The effects of hydrothermal conditions on the nanostructure, chemical stability and ion-exchange property of the LiMn2O4 spinel and MnO2 ion-sieve are examined via powder X-ray diffraction (XRD), N2 adsorption–desorption at 77 K, high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED) and lithium ion selective adsorption measurements. The results show that the 1D MnO2 nanorods might be utilized in lithium extraction from aqueous environment including brine, seawater and waste water.