Chemical Engineering Department, University of Mohaghegh Ardabili, P.O. Box 179 Ardabil, I.R. IRAN
Abstract
In this paper, a new mixing rule for predicting the surface tension of liquid mixtures is presented. The resulting equation is provided by a combination of Gibbs- Vollmer relation and NRTL activity coefficient model. The proposed model accurately predicts the surface tension of aqueous and non-aqueous solutions in a wide range of concentration. In order to evaluate the ability of this model, several surface tension of binary liquid systems were measured tensiometer (Kruss K20 Easy Dyne). The experimental data available in the literature also were used to prove the accuracy of the model. The results showed that the proposed model can predict accurately the experimental data in a wide range of concentration. Data of non-aqueous solutions were predicted with high precision as absolute average error of less than 1% was achieved for most of these systems. For aqueous systems with a high degree of non-ideality the deviation from experimental data is higher than other systems (up to 10%). This error occurred because the molecules with strong hydrogen bonds that can form a complex non-ideal mixture, even the use of accurate activity coefficient model could not eliminate completely the error. However, the model predictions are satisfactory and acceptable.
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