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UNIQUAC
About: UNIQUAC is a research topic. Over the lifetime, 2908 publications have been published within this topic receiving 53973 citations.
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TL;DR: The UNIQUAC equation as discussed by the authors is a semi-theoretical equation for the excess Gibbs energy of a liquid mixture, which is generalized through introduction of the local area fraction as the primary concentration variable.
Abstract: To obtain a semi-theoretical equation for the excess Gibbs energy of a liquid mixture, Guggenheim's quasi-chemical analysis is generalized through introduction of the local area fraction as the primary concentration variable. The resulting universal quasi-chemical (UNIQUAC) equation uses only two adjustable parameters per binary. Extension to multicomponent systems requires no ternary (or higher) parameters.
The UNIQUAC equation gives good representation of both vapor-liquid and liquid-liquid equilibria for binary and multicomponent mixtures containing a variety of nonelectrolyte components such as hydrocarbons, ketones, esters, amines, alcohols, nitriles, etc., and water. When well-defined simplifying assumptions are introduced into the generalized quasi-chemical treatment, the UNIQUAC equation reduces to any one of several well-known equations for the excess Gibbs energy, including the Wilson, Margules, van Laar, and NRTL equations.
The effects of molecular size and shape are introduced through structural parameters obtained from pure-component data and through use of Staverman's combinatorial entropy as a boundary condition for athermal mixtures. The UNIQUAC equation, therefore, is applicable also to polymer solutions.
4,130 citations
TL;DR: In this article, a group-contribution method is presented for the prediction of activity coefficients in nonelectrolyte liquid mixtures, which combines the solution-of-functional-groups concept with a model for activity coefficients based on an extension of the quasi chemical theory of liquid mixture (UNIQUAC).
Abstract: A group-contribution method is presented for the prediction of activity coefficients in nonelectrolyte liquid mixtures. The method combines the solution-of-functional-groups concept with a model for activity coefficients based on an extension of the quasi chemical theory of liquid mixtures (UNIQUAC). The resulting UNIFAC model (UNIQUAC Functional-group Activity Coefficients) contains two adjustable parameters per pair of functional groups.
By using group-interaction parameters obtained from data reduction, activity coefficients in a large number of binary and multicomponent mixtures may be predicted, often with good accuracy. This is demonstrated for mixtures containing water, hydrocarbons, alcohols, chlorides, nitriles, ketones, amines, and other organic fluids in the temperature range 275° to 400°K.
2,787 citations
324 citations
TL;DR: In this paper, the energy requirements of the NH3-CO2-H2O system were studied using the Extended UNIQUAC electrolyte model developed by Thomsen and Rasmussen in a temperature range from 0 to 110 ǫC and pressure up to 100 bars.
320 citations
TL;DR: In this article, the Redlich-Kister equation was used to predict the dynamic viscosities of methanol or ethanol with water, ethyl acetate, and methyl acetate.
312 citations