Studies On The Preparation Of Spinel Li_1.6 Mn_1.6 O₄ And Lithium Ion-Sieve Adsorption Properties

In the past few decase, several methods had been largely investigated from salt lake brine and seawater for lithium recovery. Absorbents of spinel manganese oxides have been aroused great interest in the study by their good shape memory. Among the spinel phase lithium manganese oxides, Li_1.6Mn_1.6O₄ has advantages in large adsorption capacity, chemical stability, and the saturation adsorption capacity of its Lithium ion-sieve, which is the largest in all kinds of Manganese Oxide"Lithium sieve"in present.Material performance is closely related to the material morphology. This study works in two ways: on the one hand the three-dimensional ordered macroporous structure is applied to Li_1.6Mn_1.6O₄ and its lithium ion-sieve, prepared for the ion-sieve material which is three-dimensional pore in micro-morphology and particles in macro-morphology. And its crystal Phase, compound stability and ion exchange properties were studied; On the other hand the precursor Li_1.6Mn_1.6O₄ was prepared by the sol-gel method, and ion sieve H1.6Mn1.6O4 was obtained by acid modified. Its crystal Phase, compound stability and ion exchange properties were studied.Together with colloidal crystal template method and sol-gel method the three-dimensional ordered macrospore spinel type lithium manganese oxide was successfully prepared, and assembled into colloidal crystal template by sedimentation. The precursor solution was composed of Mn(CH₃COO)₂·4H₂O, LiNO₃, citric acid and ethyl alcohol, whose molar ratio of Li and Mn was 1:1, and was used to fill into the colloidal crystal template. The lithium manganese oxide of three-dimensional ordered macropore was prepared with the template eliminated by calcining. The powder Li_1.6Mn_1.6O₄ was prepared by the method of sol-gel. The precursor solution was composed of Mn (CH₃COO) 2·4H₂O, LiNO₃, citric acid, whose molar ratio of Li and Mn was 1:1. After the water bath heating, electric mixer stirring and drying into a gel, spinel sol-gel Li_1.6Mn_1.6O₄ was prepared by high temperature. Using HCl solution as lithium remove reagent, Lithium in the three-dimensional ordered macroporous Li_1.6Mn_1.6O₄ and the sol-gel Li_1.6Mn_1.6O₄ were removed during different lithium remove time. Test the temperature, respectively, processing time on the two different precursor materials, as well as the two absorbents saturated adsorption capacity, performance and recycling separation performance of the two different absorbents. And in this condition the lithium separating out rate was higher and the manganese damage rate caused by dissolve was lower. The result of the two different absorbents testing showed that the maximum Li+ absorptive capacity of the three-dimensional ordered macroporous absorbent is 56.7 mg/g, getting 82.8% of the theoretical value, while the maximum Li+ absorptive capacity of the sol-gel absorbent is 41.7 mg/g, reaching 61.7% of the theoretical value. There is a higher selectivity about Li+ than Na+, K+ in the solution containing Li⁺, Na⁺, and K⁺.For human growing demand for lithium, lithium salt lake and sea water will become the future development of lithium resources; an important preparation technology for high-exchange capacity of the Li+ absorbent has become a common task in present. This work focuses on these points, and has a deep research on lithium ion-sieve H1.6Mn1.6O4 which has the largest uptake capacity of lithium in present.