Synthesis and Adsorption Properties of Li_1.6Mn_1.6O₄ Spinel

Abstract

Orthorhombic-LiMnO 2, spinel-type Li 1.6 Mn 1.6 O 4, and spinel MnO 2 ·0.5H 2 O were synthesized via a combination of hydrothermal synthesis and solid-phase reaction. o-LiMnO 2 with different stacking fault concentrations were synthesized by controlled hydrothermal reaction using a KMnO 4, MnCl 2, and LiOH mixed solution. Spinel-type Li 1.6 Mn 1.6 O 4 precursor was prepared via heat treatment of o-LiMnO 2 . The effects of hydrothermal and solid-phase reaction on the structure and ion-exchange properties were examined with powder X-ray diffraction, scanning electron microscopy, and Li + selective adsorption measurements. The results showed that stacking fault concentration of o-LiMnO 2 affects the adsorption properties of Li 1.6 Mn 1.6 O 4 . Li + adsorption capacity reached 6.06 mmol·g –1 at equilibrium. Distribution coefficients of metal ions were in the order Li + ≫ Na + > Mg 2+ > K + > Ca 2+ and were significant for Li + extraction from low grade brine. The equilibrium uptake of Li + from salt lake brine remained at 3.62 mmol·g –1 after six cycles.