| The mixture of acetonitrile and water is an azeotropic system. In order to explore whether ionic liquid has the ability to promote separation of acetonitrile and water mixed solution, we measured the isobaric vapor liquid equilibrium data of{[C4mim][C1](χA)-[C4mim][BF4](1-χA)} composite ionic liquid+acetonitrile+water system using the Eills balancing apparatus. The effects of composition and additive amount of composite ionic liquid regular effects on the phase equilibrium were studied. The experiment data was correlated by NRTL model. Further, the density, viscosity and conductivity of composite ionic liquid under different compositions and different temperatures were mrasured and then fitted by experienced model.Our experiment results show that the densities of composite ionic liquid increase with the decrease of temperature and have perfect linear functional dependence on temperature. The viscosities decline along with the increase of temperature and can be quantitatively described by Arrhenius equation. Conductivities arise with the increase of temperature. The logarithm of conductivity and temperature of the reciprocal has very good linear relationship. On the other hand, the densities increase with the increase of [C4mim][BF4] content in the composite ionic liquid, viscosities decrease and conductivities are between the two pure ionic liquid. But those properties do not present linear relation with the composition of composite ionic liquid. The results show that the azeotropic point can’t be eliminate by just adding the [C4mim][BF4] slightly. It has no obvious influence on the high concentration of acetonitrile and oppositely in the low concentration it reduces the relative volatility of acetonitrile to water. So it may increase quantity added to promote the separation of acetonitrile and water. When molar ratio ([C4mim][Cl]:[C4mim][BF4]) is2and χ3equals0.05, the azeotropic composition(with acetonitrile meter) transfers from0.7to0.82approximately. And the composite ionic liquid can remove the azeotropic point with the increasing of concentration. For another with the decrease of [C4mim][BF4] content, the ability of composite ionic liquid changing the composition of azeotropic point and the relative volatility gradually was reduced. As for this condition only adding the quantity of ionic liquid can remove the azeotropic point. Correlation results show that NRTL model is satisfied to fit the acetonitrile (1)+water (2)+[C4mim][BF4](3) ternary system experimental data. The mean absolute error of temperature is0.97K and gas phase composition is0.016. As for the acetonitrile(l)+water(2)+ {[C4mim][Cl]:[C4mim][BF4](=2:1,1:1,1:2)}(3) quaternary system, the related results by NRTL model is basically agree with the experiment results. The mean absolute errors of temperature are1.91K,1.87K,1.44K while gas phase composition are0.0322,0.0236,0.0247respectively.This work not only offer the foundation of selecting the ionic liquid for acetonitrile+water azeotrope system, but also enrich the basic physical property data of composite ionic liquid and acetonitrile+water+composite ionic liquid vapor liquid equilibrium data. |
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