Abstract
A method for obtaining nanocomposite sorbents, which are selective towards Li+ ions, has been proposed. The samples were based on adsorptive-active anatase, the selective component being lithium-manganese spinel LiMn2O4. This component was synthesized preliminarily, its nanoparticles were added to the sol of insoluble titanium hydroxocomplexes, and the nanocomposite was precipitated from this suspension and calcined at 5000C. A number of sorbents with different molar ratio of Ti:Mn were prepared via this procedure; they were investigated by means of chemical analysis, X-ray diffraction analysis, optical microscopy, transmission electron microscopy and scanning electron microscopy. The size of nanocrystallites was 20–30 nm. An increase in the spinel amount caused a decrease in the sorbent grain size; however, they the sorbent grains were mechanically durable due to TiO2 which was a binder. Adsorption of Li+ from the solution containing an excess of Na+ ions was studied. The optimal amount of LiMn2O4 (13%) was determined. The sample was obtained in the form of rather large grains (0.3 mm) and the selectivity coefficient Li+/Na+ was about 500. The sorbent was regenerated by a 1 M HNO3 solution without manganese leakage. After 10 cycles of sorption-desorption, the concentrate was obtained. This concentrate can be used for Li2CO3 precipitation.
Highlights
Lithium and its compounds are used to produce alloys, thermoelectric, optical and laser materials [1]
The addition of spinel to hydrous titanium dioxide (HTD) followed by calcination at 6000C leads to the formation of composite: the diffracrograms reveal the signals that are characteristic of anatase and lithium-manganese spinel LiMn2O4 (Fig. 2,b)
A method for obtaining nanocomposite sorbents, which are selective towards Li+ ions, has been proposed
Summary
Lithium and its compounds are used to produce alloys, thermoelectric, optical and laser materials [1]. They are used in medicine, metallurgy and pyrotechnics. In 2020, the demand for lithium will be more than 20,000 tons (lithium carbonate equivalents) [2] This metal is contained in water of some salt lakes, the most salars known being located mainly in South America. Some minerals, such as spodumene, petalit and ambligonit, contain lithium and used for producing this metal. The development of lithium deposits (salars) and the recovery of lithium from primary and secondary resources cause ecological risks [4]: alienation of fertile lands, salinization of fresh water sources, high consumption of fresh water and its pollution with soluble lithium compounds (maximal allowable concentration is 0.03 mg dm–3) and other toxic additions
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