Study On Separation Process Of Acetic Acid-Water System Under Magnetic Field

Traditional distillation process of acetic acid-water system had the disadvantages of great energy consumption, low efficiency and high operation costs. In order to improve production efficiency and reduce energy consumption, the magnetic distillation was employed. At the same time, a solid foundation for the theory of separation under the magnetic field was established. The main works were as follows:(1) Viscosity and surface tension of water, acetic acid and ethyl acetate were measured and regressed under the different magnetic induction intensities which were 0.165T, 0.240T, 0.36T and 0.55T.(2)The vapor-liquid equilibrium (VLE) of acetic acid-water system and the liquid-liquid equilibrium (LLE) of acetic acid- ethyl acetate-water system were studied under the magnetic field mentioned above. The results showed: the applied magnetic field had a positive effect on VLE and LLE of system, namely the magnetic field could improve the equilibrium constant and be helpful to separation of acetic acid-water system. However, the relationship between the applied magnetic field and the equilibrium constant was not simply linear in the acetic acid-water system. By different magnetic induction intensity and different solution density, effects of magnetic field on VLE and LLE were different to some extent too. In present study, the associating theory was also combined in calculating of acetic acid phase equilibrium, and Wilson and NRTL equation were used to correlate the VLE data while NRTL equation was used to correlate the LLE data. Finally, the effect factor of magnetic field to the VLE and LLE of acetic acid-water was proposed.(3)In order to test the magnetic effects on the acetic acid aqueous solution separation, an azeotropic distillation experiment was conducted with adding the reagent (ethyl acetate). The results showed that the acetic-water system separation benefited by using magnetic field, and with the increase of the magnetic induction intensity, the effects of the magnetic field on acetic acid system distillation raise, but the effects had optimal value. In the experiment, the acetic acid content and yield rate could increase by 4.42% and 1.44% at most.(4) By means of the luminosity and 1H NMR of the acetic acid-water system, the separation mechanism of the VLE, LLE and distillation of the system under the magnetic field was discussed. It was believed that magnetic field could affect the physical and phase equilibrium properties in the system by changing the hydrogen bond and thus achieving the separate efficiency, and there was a rational explanation to the experimental results.(5) On the basis of thermodynamic model in the external force field, the phase equilibrium model was built and used to predict the performance of VLE and LLE of different systems under the magnetic field. It also established a foundation for further study on phase equilibrium under the magnetic field in the future.