Using GV-SAFT-MSA state equation to investigate the activity coefficient of electrolyte solutions and the osmotic coefficient of ionic liquid [EMIM][BF۴]

Electrolytic solutions are a special group of engineering systems that have found wide applications in various industries such as biological systems, distillation and extraction, hydrate formation process, etc. What is important in dealing with these systems is to provide a model that can accurately express the thermodynamic behavior of the system. Electrolytic solutions exhibit highly non-ideal behavior due to the presence of long-range electrostatic forces between the ions and in complex states between the ions and the solvent. In this research, the SAFT equation has been used to study electrolytic solutions. This equation has the property that by using statistical thermodynamics and considering all intermolecular forces of materials, it can predict the thermodynamic properties of hydrogen bonded materials such as water. Taking the effect of the presence of an electrolyte, such as MSA, adds to the equation of state. A new class of organic salts has been considered as ionic liquids today. In this research, the proposed model is used to investigate the osmotic coefficient of ۱-ethyl-۳-methylimidazolium tetrafluoroborate. This work has investigated the activity coefficient of ten electrolytic solutions. Each salt in water is completely separated so that there will be three types of particles in the solution, and each particle has three adjustable parameters, which are the number of cuts, the cutting energy and the diameter of the hard-sphere. To obtain water-related parameters, vapor pressure and liquid water saturation density data are used. The obtained results show that this model can process this quantity well. The application of the proposed model to the osmotic coefficient of an aqueous solution of ionic liquid as an organic salt shows that this model can better fit this quantity than the Pitzer model and predict this quantity more accurately for different temperatures [۱].