Synthesis and Adsorption Properties of Li 1.6 Mn 1.6 O 4 by a Combination of Redox Precipitation and Solid-Phase Reaction

Orthorhombic LiMnO 2 (o-LiMnO 2 ), spinel Li 1.6 Mn 1.6 O 4 precusors, and spinel H 1.6 Mn 1.6 O 4 ion sieves were synthesized by a combination of controlled redox precipitation and solid-phase reaction. o-LiMnO 2 was synthesized by a controlled redox precipitation using Mn(OH) 2, LiOH, and (NH 4 ) 2 S 2 O 8. Spinel Li 1.6 Mn 1.6 O 4 precursor was prepared by the heat treatment of o-LiMnO 2 . Further, an ion sieve (H 1.6 Mn 1.6 O 4 ) was synthesized by the acid (HCl) treatment of Li 1.6 Mn 1.6 O 4 . The effect of redox precipitation and solid-phase reaction on the structure and ion-exchange property of the ion sieve was examined by powder X-ray diffraction, scanning electron microscopy, and Li + -selective adsorption measurements. The results showed that the ion sieve exhibited highly selective adsorption capacity for Li + (3.88 mmol·g –1 ) from Qarhan salt lake brine, which was significant for the Li + extraction from low-grade brine.