Modeling Of Solid-Liquid Adsorption And Vafour Liquid Equilibria For Ionic Liquid Containing Systems

Study of novel separation method for mixed system is of greatsignificance for the development and renovation of industrial processes.Searching for new separation method for such systems as azeotropicsystem and the system with similar structure and property, and thereforehard to be separated has long been a hotpot of separation technology.Owing to the better understanding on adsorption process and thedevelopment of new absorbent, the appearance of extractive distillation,membrane technology and ionic liquid, some integrated separationtechnologies have been appeared on the basis of combination of differenttechnologies available, which provide a new opportunity for thedevelopment and the technological advancement of separationengineering. This paper includes three sections: thermodynamic modeldevelopment for solid-liquid adsorption equilibrium; study on the effectof ionic liquid on the vapor-liquid-equilibrium (VLE) for single andmixed systems; VLE measurement for ionic liquid containing systems. III北京化工大学硕士学位论文 Solid-liquid adsorption is of great significance in Chemical Industry.Typical applications include adsorptive separation of a liquid mixture,treatment of wastewater and selectivity adjustment of heterogeneous solidcatalytic reaction etc. Based on the adsorbate-solid solution theory, athermodynamically consistent model was developed for the calculation ofadsorption equilibrium by describing interactions among adsorbates andadsorbent components with Wilson equation. This model was used forcorrelating adsorption isotherms for several binary systems such as1-octene/ n-octane,1-decene/ n-hexane,1-hexene/ n-hexane,benzene/n-heptane and benzene/ Cyclohexane, also the adsorption isotherm of1—hexene/n—hexane at other temperatures was predicted by this model,both correlation and prediction deviation were within 5%. This suggeststhat the present model has a good performance in correlating andpredicting binary adsorption isotherms, and is expected to be applicableto the calculation of solid-liquid equilibrium of practical system. Ionic liquid as a benign solvent is of great potential to be applied inchemical reaction and separation processes due to its unique attributes.And the modeling and calculation of VLE for the ionic-liquid containingsystem is of both theoretical and practical importance. By using NRTLequation for non-electrolyte solution, the VLE isotherm ofwater-[bmim][PF6] and water-[pmim][Br] was correlated and the VLEdata at other temperatures were predicted, the calculation deviation was IV北京化工大学硕士学位论文within 2%. The experimental infinite activity coefficients of some organicchemicals in ionic liquids at varying temperatures were correlatedsuccessfully with NRTL equiation, and the binary parameters thusobtained were used to study the effect of ionic liquid on the VLE ofazeotropic binary systems such as benzene-cyclohexane ,Hexane-Ethanol , cyclohexane-Ethanol , methanol-cyclohexane andmethanol-hexane. It is shown that VLE for ionic containing systems canbe well represented with conventional NRTL equation, the relativevolatility of component can be largely affected and azeotropic point caneven be eliminated by the "salt effect" of ionic liquid. This is importantin guiding the application development of ionic liquid in the extractivedistillation. The equipment for the measurement of saturated vapor pressure wasestablished, and the VLE data of water-[emim][Br] and water-[pmim][Br]binary systems were obtained. It is shown that ionic liquid can reduce thesaturated vapor pressure of water. Although this equipment is not veryaccurate, it provides a preparative work for the further study ofthermodynamic properties of ionic liquid systems.