Surface tensions of mixed aqueous solutions of tert-butanol and n-pentanol

Surface tensions of binary solutions of tert-butanol and n-pentanol at 25 °C have been measured as a function of concentration and the results fitted to the Szyszkowski equation to obtain the values of the adsorption coefficient and the limiting partial molar areas for each of the two alcohols. The surface tensions of ternary solutions containing both tert-butanol and n-pentanol were also measured and the results compared with a theory due to Butler, in which the Szyszkowski parameters derived from the binary solutions are used to predict the surface tensions of the mixed solutions. Large discrepancies were observed between the measured and predicted surface tensions. However a very good correlation was found between the experimental surface pressures of the ternary solutions and theoretical values predicted by a thermodynamic model of Fainerman and Miller for densely packed mixed monolayers of surfactants having different molar areas.