Study On Synthesis Of N,N'-dialkylimidazolium-based Ionic Liquids And Electrorefining Of Aluminu

In this paper,the intermediate bromide 1-ethyl-3-methylimidazolium salt([EMIM]Br) was synthesized by dibromoethane and N-methyl-imidazole,then hydrophilic 1-ethyl-3-methy-limidazolium tetrafluoroborate([EMIM]BF₄) and hydrophobic 1-ethyl-3-methy-limidazolium hexafluorophosphate([EMIM]PF₆) have been synthesized by [EMIM]Br with NaBF₄,KPF₆ At the same time,its physical properties were determinated,and its purity was studied,the structures was characterized by IR and UV spectrum.[BMIM]BF₄ was also synthesized,its physical properties were measured,and its structure was verified by IR and UV spectrum.It was demonstrated that the density is decreased with the increasing of temperature;the electrical conductivities and viscosity are increased with the increasing of temperature.The logarithm of the electrical conductivities and viscosity are linear relationship with the reciprocal of temperature.The activation energy of conductivity is greater than the viscosity,the changes of the conductivity with the temperature isn't severe as viscosity.The influence of the organic solvents on the conductivity is studied.The conductivity of ionic liquids with the increasing of the concentration of organic solvents first increased and then decreased.The impact of the order is:CH₃COCH₃＞CH₃OH＞CCl₄.An ionic liquid was prepared by mixing AlCl₃ and 1-methyl-3-butylimidazolium bromide (BMIM) under dry nitrogen atmosphere.The structure of(BMIM)Br-AlCl₃ was confirmed by IR and UV.Aluminum electrolysis was conducted 16h at 298.15K by the ionic liquid.Cathode surface was analyzed by SEM and EDS.The results showed that the(BMIM)Br-AlCl₃ had been electrorefined of aluminum;The crystal grain of new deposit aluminum was ideal,and the boundary of crystal grain was perfect.The main element was aluminum;trace element was oxygen on the surface of cathode.