Study Of Rheological Properties Of Magnetic Ionic Liquids

As new functionalized ionic liquids and magnetic fluids,magnetic ionic liquids have attracted great interest in applications such as separation and catalysis,and have now become a research hotspot in the field of chemical separation and process intensification.The rheological properties of magnetic ionic liquids not only help to understand their physicochemical structure but also provide important information for their engineering applications,which is of great importance for the scientific research and industrial applications of magnetic ionic liquids.At present,there are few studies on the rheological properties of magnetic ionic liquids,and there is a gap in the study of the rheological properties of mixed systems with organic solvents.Based on the above considerations,the main research contents and results of this paper are as follows.Three magnetic ionic liquids,[Bmim][FeCl4],[P6,6,6,14][FeCl4],[TMG][FeCl4],was synthesized,and the accuracy of the combined magnetic ionic liquids was verified by infrared,Raman and mass spectrometry detection methods The rheological data of[Bmim]PF6 were measured and compared with literature data to verify that the rheometer used was accurate.The rheological properties of three magnetic ionic liquids were investigated by HAAKE rotational rheometer,and dynamic rheological tests showed that both[Bmim][FeCl4]and[TMG][FeCl4]exhibited viscous characteristics,and[P6,6,6,14][FeCl4]had a special viscoelasticity;steady-state rheological tests showed that the three magnetic ionic liquids are non-Newtonian fluids with shear thinning characteristics,and the increase in temperature will not change the shear thinning characteristics of the ionic liquids but will cause shear-thinning to occur at higher The increase in temperature does not change the shear thinning characteristics of the ionic liquids but will cause the shear-thinning to occur at higher shear rates,which is due to the destruction of the internal hydrogen bonding network structure of the magnetic ionic liquids resulting in a decrease in viscosity.The rheological data were fitted based on a rheological model to obtain the best rheological equation consistent with magnetic ionic liquids,and the temperature dependence of viscosity was fitted by Arrhenius,Power-law,VFT,Litovitz,and Ghatee models,and the applicability of the models was discussed.The rheological properties of two binary hybrid systems,DMSO+[Bmim][FeCl4]and EtOH+[Bmim][FeCl4],were investigated,and the effects of shear rate,temperature,and concentration on the rheological properties were analyzed.The experimental results showed that similar to pure magnetic ionic liquids,the two-hybrid systems exhibited viscous characteristics in the measurement frequency range,and the addition of EtOH and DMSO weakened the non-Newtonian properties of[Bmim][FeCl4],and the viscosity of the hybrid systems decreased significantly,which was due to the addition of organic solvents disrupting the internal hydrogen bonding network structure of[Bmim][FeCl4],resulting in the reduction of viscosity.The effect of temperature on the apparent viscosity of the mixed system was described using the Arrhenius equation,and the results showed that the effect of temperature on the apparent viscosity of the mixed system with the addition of EtOH was less than that with the addition of DMSO,and the solution was relatively stable.As the molar fraction of EtOH and DMSO in[Bmim][FeCl4]increases,the viscosity of the mixed solution gradually decreases,and the lower the temperature,the more obvious the trend of viscosity decrease.The concept of excess viscosity is introduced to indicate the deviation of the actual value of the binary system from the ideal value,and the results show that the excess viscosity Δη of the binary mixed system of EtOH+[Bmim][FeCl4]is less than zero,indicating that there is a negative deviation between the mixed system and the ideal solution;the excess viscosity Δη of the DMSO+[Bmim][FeCl4]system increases first and then decreases with the increase of the molar fraction of DMSO.