(290g) Prediction of Surface Tension for Dilute Binary Aqueous Systems Using a Molecular Thermodyanmic-Based Model

A molecular thermodynamic-based model was used to find the surface tension of binary aqueous polar mixtures. The model incorporates the contributions to surface tension from three additive terms: hard sphere, dispersion, and polar interactions. The model has two adjustable parameters related to size and energy. Amines and glycol ethers were chosen as they are used as shrinkage reducing admixtures of concrete. The pure component parameters obtained from the model were used to determine the surface tension of binary aqueous mixtures using two binary interaction parameters. The overall average absolute percentage deviation (AAD %) obtained for 17 amines and 5 glycol ethers, were 6.25% and 4.33% respectively. An attempt to use the average binary interaction parameters relative to individual binary parameters of specific class of compounds was made. Since only small quantities of admixtures are used in concrete, the binary interaction parameters for the surface tension reduction in dilute systems were calculated and the predictive ability of the model was analyzed by evaluating the slope of the surface tension vs composition plot.