Vapor-liquid equilibrium (VLE) data of solutions are necessary for the design of distillation and absorption processes. VLE exhibits various characteristics depending on the type of solution. In the case of nonideal solutions, an azeotropic mixture is formed which cannot be separated by ordinary distillation. The mixture must be separated by adding a third component, called an entrainer, which has the capability of breaking the azeotropic point. In most cases, a volatile component is employed as an entrainer for an azeotropic mixture. However, salt is also effective in breaking the point; this is called the salt effect on VLE. Much has been observed on salt effect, however very few commercial distillation plants use this method. This book aims to cover all reported data found in journals on salt effect on VLE. Prediction methods for VLE at low and high pressures for systems composed of volatile substances are used routinely, However, no method to predict the salt effect on VLE is in use, because salts show entirely different behavior from volatile substances. A method to predict salt effect based on preferential solvation was reported by the author in 1976.30 systems were examined and the formation of preferential solvates between the salt and one of the volatile components was shown. Continuing the work, the formation of preferential solvates for almost all salt effect data has been examined. As a result of this work, it has been found that preferential solvates are formed without exception. In this volume, the preferential solvation numbers determined by least squares method are shown by processing the data of salt effect on VLE.

Vapor-Liquid Equilibria Using UNIFAC: A Group-Contribution Method focuses on the UNIFAC group-contribution method used in predicting quantitative information on the phase equilibria during separation by estimating activity coefficients. Drawing on tested vapor-liquid equilibrium data on which UNIFAC is based, it demonstrates through examples how the method may be used in practical engineering design calculations. Divided into nine chapters, this volume begins with a discussion of vapor and liquid phase nonidealities and how they are calculated in terms of fugacity and activity coefficients, respectively. It then introduces the reader to the UNIFAC method and how it works, the procedure used in establishing the parameters needed for the model, prediction of binary and multicomponent vapor-liquid equilibria for a large number of systems, the potential of UNIFAC for predicting liquid-liquid equilibria, and how UNIFAC can be used to solve practical distillation design problems. This book will benefit process design engineers who want to reliably predict phase equilibria for designing distillation columns and other separation processes.

The salt effect has been studied enthusiastially nerally two decades. Many researchers have tried to explain and predict the behavior. But no general model has been developed so far. In order to improve the Schmitt and Vogelpohl's model the concept of preferential association among the electrolyzed ions of salt and molecules of solvents is used to redefine the distribution factor of salt in the mixture, and the original model is modified. The results show that this modification is reasonable and will give the more accurate prediction of salt effect on the vapor-liquied equilibrium of the binary systems. [Authors' abstract].

The classic guide to mixtures, completely updated with new models, theories, examples, and data. Efficient separation operations and many other chemical processes depend upon a thorough understanding of the properties of gaseous and liquid mixtures. Molecular Thermodynamics of Fluid-Phase Equilibria, Third Edition is a systematic, practical guide to interpreting, correlating, and predicting thermodynamic properties used in mixture-related phase-equilibrium calculations. Completely updated, this edition reflects the growing maturity of techniques grounded in applied statistical thermodynamics and molecular simulation, while relying on classical thermodynamics, molecular physics, and physical chemistry wherever these fields offer superior solutions. Detailed new coverage includes: Techniques for improving separation processes and making them more environmentally friendly. Theoretical concepts enabling the description and interpretation of solution properties. New models, notably the lattice-fluid and statistical associated-fluid theories. Polymer solutions, including gas-polymer equilibria, polymer blends, membranes, and gels. Electrolyte solutions, including semi-empirical models for solutions containing salts or volatile electrolytes. Coverage also includes: fundamentals of classical thermodynamics of phase equilibria; thermodynamic properties from volumetric data; intermolecular forces; fugacities in gas and liquid mixtures; solubilities of gases and solids in liquids; high-pressure phase equilibria; virial coefficients for quantum gases; and much more. Throughout, Molecular Thermodynamics of Fluid-Phase Equilibria strikes a perfect balance between empirical techniques and theory, and is replete with useful examples and experimental data. More than ever, it is the essential resource for engineers, chemists, and other professionals working with mixtures and related processes.