Research Of Character, Structure And Electrochemical Behavior Of Analogous Ionic Liquids Containing Magnesium

In recent years, more and more researchers focus on analogous ionic liquids. Analogous ionic liquids are a new environmentally friendly green solvent due to its high solubility, non-toxic, biodegradable and low cost. Analogous ionic liquids has widely application prospects in many fields, such as electrochemistry, organic synthesis, dissolution, extraction, separation, catalysis, materials chemistry and so on.Qarham salt lake in China is well-known for its huge reserves of magnesium chloride after the exploitation of potash salts. It is necessary to utilize the magnesium chloride effectively in wide areas. Preparation of magnesium analogous ionic liquids using magnesium chloride as the raw material is one of the methods. The magnesium analogous ionic liquids can be applied to electrodeposite the metallic magnesium. Study of the physical-chemical properties the structure of magnesium analogous ionic liquids can provide a theoretical basis for the research on the electrochemical behavior of analogous ionic liquids. It also give an impotant information to the high-value utilization of the magnesium reserves rich in salt lakes.In the paper, the analogous ionic liquids based on hydrated magnesium chloride were synthesized, and their physical-chemical properties have been carried out. The structure of the analogous ionic liquid is analyzed by Fourier transform infrared spectroscopy(FTIR), Raman spectroscopy(Raman) and Density functional theory(DFT). The electrochemical behavior of analogous ionic liquid was also preliminarily investigated. The main work is as follows:(1) The analogous ionic liquid of MgCl2·6H2O-ChClA homogeneous, colorless analogous ionic liquid containing choline chloride and magnesium chloride hexahydrate was prepared. The melting point of analogous ionic liquid was measured by DSC. The viscosity, conductivity, density were determinated as a function of temperature and compositions. The structure of Mg Cl2 6H2O-Ch Cl was analyzed by FTIR, Raman and DFT. The main species in the system were obtained.(2) The analogous ionic liquid of Mg Cl2-EG-Ch ClFirst, the solubility of Ch Cl in EG, and the Mg Cl2 in analogous ionic liquid EG-Ch Cl were measured by isothermal method. Then, based on the solubilty data, an amount of Mg Cl2 was added to the analogous ionic liquid of EG-Ch Cl to the form colorless, clear and homogeneous analogous ionic liquid of Mg Cl2-EG-Ch Cl. The physic-chemical properties of the analogous ionic liquid such as viscosity, conductivity, density and p H were measured as a function of temperature and compositions. The structure of Mg Cl2-EG-Ch Cl was analyzed by FTIR. Thermal analysis shows that the Mg Cl2-EG-Ch Cl is stable from room temperature to 433 K.(3) The analogous ionic liquid of Mg Cl2-Urea-ChClThe analogous ionic liquid Urea-Ch Cl(mole ratio, 2:1) was synthesized. Then an amount of Mg Cl2 was added to Urea-Ch Cl according to form the clear and homogeneous analogue ionic liquid of Mg Cl2-Urea-Ch Cl. The viscosity, conductivity and density were measured as a function of temperature and compositions. The thermodynamic parameters were calculated according to physic-chemical properties. The structure of Mg Cl2-Urea-Ch Cl was analyzed by FTIR. Thermal analysis was also carried out according to the TGA curve.(4) The electrochemical behavior of Mg2+ in analogous ionic liquidThe electrochemical behavior of analogous ionic liquid of Mg Cl2·6H2O-Ch Cl、Mg Cl2 6H2O-DMF、Mg Cl2-EG-Ch Cl、Mg Cl2-Urea-Ch Cl and [BMP][Tf2N]-Et Mg Br were measured by cyclic voltammetry curves and electrochemical impedance spectroscopy. The possibility of magnesium electrodeposition was explored. And the metal magnesium was obtained by potentiostatic deposition. The XRD, EDS and SEM are used to analyze the content and deposition morphology.