Group‐contribution estimation of activity coefficients in nonideal liquid mixtures

TLDR

The study introduces a group‑contribution method to predict activity coefficients in nonelectrolyte liquid mixtures. The method merges a solution‑of‑functional‑groups framework with an extended quasi‑chemical theory, yielding a UNIFAC‑like model that uses two adjustable parameters per functional‑group pair. Using group‑interaction parameters derived from data reduction, the model accurately predicts activity coefficients for many binary and multicomponent mixtures, including water, hydrocarbons, alcohols, chlorides, nitriles, ketones, amines, and other organics over 275–400 K.

Abstract

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 ( UNI QUAC F unctional‐group A ctivity C oefficients) 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.