Shiqiang Wang

Interference of Lithium in Measuring Magnesium by Complexometry: Discussions of the Mechanism

There is usually a large concentration of magnesium in the brine of salt lakes and as a consequence it is difficult to measure Mg2

Solid-liquid phase equilibria in the ternary system (LiBO2 + Li2CO3 + H2O) at 288.15 and 298.15 K

Experimental studies on the solubilities and physicochemical properties including density, refractive index and pH value in the ternary systems (LiBO2 + Li2CO3 + H2O) at 288.15 and 298.15 K were determined with the method of isothermal dissolution equilibrium. Based on the experimental results, the phase diagrams and their corresponding physicochemical properties versus composition diagram in the system were plotted. In the phase diagrams of the ternary system at 288.15 and 298.15 K, there are one eutectic point and two crystallization regions corresponding to lithium metaborate octahydrate (LiBO2 · 8H2O) and lithium carbonate (Li2CO3), respectively. This system at both temperatures belongs to hydrate type I, and neither double salt nor solid solution was found. A comparison of the phase diagrams for this ternary system at 288.15 and 298.15 K shows that the solid phase numbers and exist minerals are the same, and the area of crystallization region of Li2CO3 is increased obviously with the increasing temperature while that of LiBO2 · 8H2O is decreased. The physicochemical properties (density, pH value and refractive index) of the solutions of the ternary system at two temperatures changes regularly with the increasing lithium carbonate concentration. The calculated values of density and refractive index using empirical equations of the ternary system are in good agreement with the experimental values.

Supercooling and Phase Separation of Inorganic Salt Hydrates as PCMs

Inorganic salt hydrates as a new type of clean and renewable energy storage materials are widely used in a variety of fields due to their high volumetric latent storage density. However, the supercooling and phase separation effects limit their applications. In this paper, the characteristics of inorganic salt hydrates as PCMs were introduced, and the supercooling and phase separation for inorganic salt hydrates as PCMs were summarized in details. Then, some new approaches of nucleating and thickening agents to overcome the supercooling and phase separation were presented. Finally, the prospects and new trends of salt hydrates as PCMs in the future were also demonstrated.

Studies on Magnesium Chloride Hexahydrate as Phase Change Materials

Magnesium chloride hexahydrate (MgCl2•6H2O), which has a melting temperature of 389.7 K and latent heat of 168.6 kJ/kg, is one of the cheapest materials used as the thermal energy storage material. Like most hydrated salts, MgCl2•6H2O also has the problems of supercooling and phase segregation to limit its application. In this paper, some new progresses on magnesium chloride hexahydrate as phase change materials are summarized, and the new trend in the future is pointed out.

Thermal Characteristics of Room Temperature Inorganic Phase Change System Containing Calcium Chloride

A novel inorganic calcium-based phase change material(PCM-Ca) consisted of 47.1%(mass fraction) water, 47.7% calcium chloride, 2% potassium nitrate, 2% potassium bromide and 1.2% strontium chloride with a solid-liquid phase change temperature of 21.4 °C was investigated systematically. Among the components of PCM-Ca, calcium chloride and water act as the latent heat storage materials, and potassium nitrate, potassium bromide and strontium chloride work as the modifier, thickener and nucleating agent, respectively. Thermochemical properties including melting point, latent heat, density and thermal conductivity of the PCM-Ca were measured experimentally. The experimental results indicate that the melting latent heat, thermal conductivity at the melting point and density at room temperature for the PCM-Ca are 203.3 kJ/kg, 1.3637 W·m–1·K–1 and 1.55×103 kg/m3, respectively. Moreover, a thirty-run-cycling test showed that the PCM-Ca has a good thermal characteristic with no phase segregation or supercooling, and the maximum deviations of latent heat and phase change temperature are only 0.2% and 1.6%, respectively.

Ionic Liquid Extraction Methods for Alkali and Alkaline Earth Metal Ions

Ionic liquids (ILs) have been considered as successful alternative extraction solvents, especially, they have become potential replacements of volatile organic compound in the extraction of metal ions for the properties of negligible vapor pressure, nonflammability, high thermostability, etc. In this paper, ILs as environmental friendly solvents in liquid-liquid extractions of alkali and alkaline earth metal ions were summarized, the part of extraction phase compositions, extraction conditions and back extraction method were discussed, and the potency of applications of ILs in extraction and separation of metal ions were also commented.

Solubility Prediction for the Reciprocal Quaternary System (Li+, Mg2+//Cl-, SO42-–H2O) at 273.15 K Using Pitzer Ion-Interaction Model

Solubilities of the reciprocal quaternary system (Li+, Mg2+//Cl-, SO42-–H2O) at 273.15K were calculated using Pitzer and its extended HW model. The values of the Pitzer single-salt parameters β(0), β(1), β(2) and Cφ for LiCl, MgCl2, Li2SO4, and MgSO4, the mixed ion-interaction parameters θLi,Mg, θCl,SO4, ψLi,Mg,Cl, ψLi,Mg,SO4, ψLi,Cl,SO4 and ψMg,Cl,SO4, and the Debye–Hückel parameter Aφ in the system at 273.15K were derived either temperature-dependent equation or through fitting solubility data of the ternary system by multiple linear regression method. Based on the Jänecke indexes, the phase diagram was plotted. This study affords the necessary parameters for solubility predictions of complicated systems and establishes a theoretical basis for the separation of these valuable minerals from salt lake brine.

Lithium Recovery Techniques from Solid and Liquid Mineral Resources

Lithium and its compounds are important materials in industry. In this paper, lithium recovery methods both from solid ores and brines were summarized, and the key problems existed were also pointed out. More details for lithium recovery from brines by solvent extraction, ion-exchange, precipitation and calcination leaching methods were discussed, and the new trend for lithium recovery in the future was also carried out.

Boron removal from seawater desalination by RO

Although a number of papers describing the boron removal methods from seawater in the past decades, the reverse osmosis (RO) for boron removal from seawater desalination is consider as one of the simplest and most promising methods. The new progresses on boron removal from seawater by RO membranes and its major effect parameter including operating temperature, operating pressure, solution pH, feed ionic strength, initial boron concentrate, membrane fouling, and so on was reviewed with 22 references. Characteristics of the processes and their operating parameters were summarized. The highlight and the new trend in the future on basic research to understand the boron rejection by reverse osmosis membranes was pointed out.

Phase and Physicochemical Properties Diagrams of Quaternary System Li 2 B 4 O 7 + Na 2 B 4 O 7 + Mg 2 B 6 O 11 + H 2 O

The phase and physicochemical properties diagrams of the quaternary system (Li2B4O7 + Na2B4O7 + Mg2B6O11) at 288.15 K and 0.1 MPa were constructed using the solubilities, densities, and refractive indices measured. In the phase diagrams of the system there are one invariant point, three univariant isothermic dissolution curves, and three crystallization regions corresponding to Li2B4O7 · 3H2O, Na2B4O7 · 10H2O, and Mg2B6O11 · 15H2O, respectively. The solution density, refractive index of the quaternary system changes regularly with the increasing of Li2B4O7 concentration. The calculated values of density and refractive index using empirical equations of the quaternary system are in good agreement with the experimental values.