Novel approaches for lithium extraction from salt-lake brines: A review

Manganese oxide octahedral molecular sieves (OMS) are important materials in environmental chemistry, electrochemistry, and heterogeneous catalysis. Here, a rapid process to prepare cryptomelane-type octahedral molecular sieve (OMS-2) nanomaterials using a microwave assisted hydrothermal technique (MW-HT) is presented. With the assistance of microwaves in the hydrothermal reaction, the preparation time of OMS-2 can be as short as 10 s; up to 4 days are required in a conventional hydrothermal reaction. Direct observation of reaction temperature and pressure in the hydrothermal reaction can be achieved in real time in the reaction process. Reaction time and temperature are two parameters chosen to examine the formation conditions of OMS-2 materials. A reaction temperature below 80 °C resulted in the formation of amorphous manganese oxide material, whereas crystalline phase OMS-2 materials were formed at increased reaction temperatures to 100 °C or above. Studies by field emission scanning electron microscop...

Microwave-Assisted Hydrothermal Synthesis of Cryptomelane-Type Octahedral Molecular Sieves (OMS-2) and Their Catalytic Studies

In this paper, we carried out a combination of permanent scatterer and quasi permanent scatterer time-series InSAR image analyses to extract geometric information over the area of the Three Gorges Dam. For the first time, we measured and analyzed the deformation of the Three Gorges Dam and its surrounding area using 40 SAR images acquired from 2003 to 2008. Our results indicate that the temporal deformation of the left part of the dam has ceased and that the deformation of the dam was influenced by the changing level of the Yangtze River. Seasonal deformation due to varying temperature is also observed. The obtained results agree well with the published results of the Three Gorges Dam deformation obtained by employing conventional survey methods. We also found that there is an area of abnormal subsidence near Zigui County. This paper demonstrates the potential of time-series InSAR image analysis in the monitoring of dam stability and measurement of subsidence.

Three Gorges Dam stability monitoring with time-series InSAR image analysis

We report a petrographic and mineralogical survey of tochilinite/cronstedtite intergrowths (TCIs) in Paris, a new CM chondrite considered to be the least altered CM identified to date. Our results indicate that type-I TCIs consist of compact tochilinite/cronstedtite rims surrounding Fe-Ni metal beads, thus confirming kamacite as the precursor of type-I TCIs. In contrast, type-II TCIs are characterized by complex compositional zoning composed of three different Fe-bearing secondary minerals: from the outside inwards, tochilinite, cronstedtite, and amakinite. Type-II TCIs present well-developed faces that allow a detailed morphological analysis to be performed in order to identify the precursors. The results demonstrate that type-II TCIs formed by pseudomorphism of the anhydrous silicates, olivine, and pyroxene. Hence, there is no apparent genetic relationship between type-I and type-II TCIs. In addition, the complex chemical zoning observed within type-II TCIs suggests that the alteration conditions evolved dramatically over time. At least three stages of alteration can be proposed, characterized by alteration fluids with varying compositions (1) Fe- and S-rich fluids; (2) S-poor and Fe- and Si-rich fluids; and (3) S- and Si-poor, Fe-rich fluids. The presence of unaltered silicates in close association with euhedral type-II TCIs suggests the existence of microenvironments during the first alteration stages of CM chondrites. In addition, the absence of Mg-bearing secondary minerals in Paris TCIs suggests that the Mg content increases during the course of alteration.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/maps.12625

Multiple precursors of secondary mineralogical assemblages in CM chondrites

Lithium λ-MnO2 ion-sieves were prepared from spinel LiMn2O4 via treatment with nitric acid. The LiMn2O4 was synthesized by a solid state reaction between LiOH·H2O and MnO2. The effects of the calcination time and temperature on the preparation of the LiMn2O4 precursor and the lithium ion-sieve were investigated. In addition, the Li+ extraction ratio, the Mn2+ dissolving ratio and the adsorption properties of the lithium ion-sieve were all measured. The lithium ion-sieve had a high exchange capacity and was selective for Li+. Specifically, at pH = 13, the ion exchange capacity of Li+ was 30.9 mg/g in 10 mmol/L LiCl solution and the lithium extraction ratio and manganese dissolving ratio were 95% and 25%, respectively.

Preparation and characterization of lithium λ -MnO 2 ion-sieves

λ-MnO2 was prepared by column method from normal spinel LiMn2O4 with purity of 99.38%. The influence of LiMn2O4 grain size and acidity of leaching solution on the lithium leaching process was studied. The results show that the appropriate range of LiMn2O4 grain size was 60–160 meshes and the concentration of leaching solution HCl was 0.1 mol·L−1. The adsorption capacity Q of λ-MnO2 for lithium increased with the increase of pH and changed markedly at pH 6.0–10.0. It was 3.80mmol/g at pH 12.0 The distribution coefficients Kd of Li+ and Na+ were 3.406×104 and 2.300 respectively, and the separation coefficient a
 Na
 Li
 was 1.481 ×104 at pH 6.5. As a result, λ-MnO2 is a high performance ion-sieve material for lithium ion.

Preparation of λ-MnO2 by column method and its ion-sieve property

By using self-made metal-alkoxide yttrium isopropoxide as a sintering additive and disperser of whisker, the SiC whisker reinforced AlN ceramics was prepared. Its apparent density is 99.5 percent of the theoretical density; its flexural strength and fracture toughness are 681 MPa and 5.21 MPa·m1/2 respectively. Comparing the result with that by applying Y2O3 powder as a sintering additive, the flexural strength is increased by 25% and the fracture toughness is increased by 33%. The dispersity of whisker by increased yttrium isopropoxide is significantly better than that by Triton X-100.

The influence of yttrium isopropoxide on the mechanical properties of SiCw-reinforced AIN ceramics

The sol-gel process of citric acid chelating with metal cations for the synthesis of normal spinel LiMn2O4 and the reaction mechanism were investigated by means of XRD, IR, TG-DTA and SEM. The results show that at the beginning lithium citrate and chelate compound of citric acid with manganese ions formed, and then with heating the esterification and condensation reactions occured between them and glycol. The products obtained are polymers in which metal cations are distributed homogenously on atomic scale that ensure high reactivity to cations of Li+ and Mn2+. Firing the gel prepared by this process, the lattice diffusions of solid reactant ions caused by non-homogeneity of reactants are eliminated and avoided. At 400°C phase-pure LiMn2O4 with nanometer scale crystallization having precise stoichiometry and perfect crystallization can be obtained. The model of chelate coordinate of double-molecule between citric acid and Mn2+ in the gel network is proposed. It is important for explaining the dispersion state of Mn2+ and the formation process of gel by this model.

Sun Yu-bin

Papers

Preparation of λ-MnO2 by column method and its ion-sieve property

The influence of yttrium isopropoxide on the mechanical properties of SiCw-reinforced AIN ceramics

The mechanism of Sol-Gel synthesis of normal spinel LiMn2O4 with chelation of citric acid

A microtubular structural amakinite