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Single-Stage Solvent Extraction
Published in Alan M. Lane, Separation Process Essentials, 2019
Vapor–liquid equilibrium (VLE) is described well for most systems by Raoult’s law, or a modified Raoult’s law if the system is not ideal. In the latter case, a model is used to calculate the liquid-phase activity coefficient. For the ethanol–water system, we used the Wilson equation. Describing liquid–liquid equilibrium (LLE) is more problematic because both liquids are non-ideal as evidenced by their forming two immiscible phases. The most common activity coefficient models for these systems are the semi-empirical NRTL (non-random, two liquid) and UNIQUAC (UNIversal QUAsiChemical). These are rather difficult to calculate. The NRTL equation will be presented in an optional section at the end of this chapter.
Non-ideal liquid solutions modeling by means of integral methods
Published in B Bertram, C Constanda, A Struthers, Integral methods in science and engineering, 2019
D. Ursutiu, A. Duta-Capra, D. Nanu, P. Cotfas
The non-ideal behavior of liquid solutions influences all other properties and is important in vapor-liquid equilibrium calculations. Estimating the activity coefficient is the most common way to describe nonideality. It can be calculated using integral methods using an equation of state that allows the calculation of the pure component properties. Mixture properties are estimated using a set of mixing rules. This paper presents results obtained for binary hydrocarbon solutions, using the general equation of state (GEOS, 1986) and Van der Waals mixing rules. The dependence of the activity coefficient on temperature and compositions is found to be significant when the hydrocarbons are very different in size. One of the most important separation processes, distillation, is the result of vapor-liquid equilibrium, VLE. So, the design of the devices used in distillation installation is based on VLE calculations. This paper presents a Lab VIEW program, which allows VLE prediction calculation, for binary systems at high pressures.
Measurement and correlation of vapour-liquid equilibria for cyclopentylmethylether + acetic acid at atmospheric pressure
Published in Alka Mahajan, B.A. Modi, Parul Patel, Technology Drivers: Engine for Growth, 2018
Experimental vapour-liquid equilibrium (VLE) data are the primary requirement for equipment design for separation of mixtures, especially, the distillation operation, for the recovery of solvents for recycling. Cyclopentylmethylether (CPME), an ethereal solvent, being considered as one of the green solvents, exceeds other ethereal solvents regarding EHS (environmental, health and safety) aspects as per GlaxoSmithKline’s solvent selection guide (Henderson, et al., 2011). The properties such as the low formation of peroxides, high boiling point, lower evaporation energy and better stability in acidic and basic conditions make CPME a stable solvent for a wide variety of chemical production (Anastas, 2015). It also satisfies 8 out 12 principles of green chemistry developed by P.T. Anastas and J.C. Warner in 1991 (Sakamoto, 2013). Acetic acid is used to produce intermediates such as vinyl acetate and acetic anhydride which are used to make latex emulsion resins for paints, adhesives, paper coatings, textile finishing agents, cellulose acetate fibers, cellulosic plastic, etc. It is also an important organic raw material which is widely used in the organic synthesis, pharmaceuticals, dyes and intermediates, pesticides and other chemical industries (Kirk-Othmer, 1998).
Systematic study of vapour–liquid equilibria in binary mixtures of fluids with different polarity from molecular simulations
Published in Molecular Physics, 2022
Joshua Marx, Maximilian Kohns, Kai Langenbach
The vapour–liquid equilibrium (VLE) is a fundamental characteristic of fluid mixtures and important for a large variety of chemical engineering applications. In particular, VLE data for simple model fluids and mixtures thereof can facilitate an understanding of how phase behaviour is influenced by interactions on the molecular level. Such insights, apart from being of intrinsic interest, may also be used to develop and test tools for the prediction of the thermodynamic properties of fluid mixtures, such as perturbation theories [1–3]. Making accurate predictions for mixtures is particularly challenging when the constitutive components differ substantially with respect to their polar properties [4]. Therefore, an extensive data base for VLE of mixtures of simple model fluids with different polarity is required to develop, test and validate such theories.