Surface properties and surface thickness of aqueous solutions of alcohols

Surface properties and surface concentrations of binary mixtures of aliphatic alcohols (methanol, ethanol, 1-propanol and 2-propanol) with water have been calculated by surface tension data at various temperatures (293.15-323.15) K. The surface tension data over the entire concentration range are correlated by the Fu et al. (FLW) and Myers-Scott (MS) models. The average relative error obtained from the comparison of experimental and calculated surface tension values for 28 binary systems (the four systems at seven temperatures) with two models is <2%. Also, the UNIFAC group contribution model is applied for calculation of activity coefficients of components in solution. The adsorption isotherms of binary aqueous solutions of alcohols are determined using Gibbs adsorption equation with experimental surface tension data and the calculated activities of alcohols. The obtained results show that the values of adsorption for mixtures of alcohols/water increase with increasing the alkyl chain length of alcohol and decreasing temperature. In addition to find more information about surface structure of binary mixtures, the thickness of surface layer as a function of composition and temperature has been obtained by relative Gibbs adsorption and surface mole fraction (from EL model). (C) 2016 Published by Elsevier B.V.