Measuring and modeling the composition and temperature-dependence of surface tension for organic solutions

Surface tensions for a wide variety of pure organic and mixed organic/salt solutions were measured at 25 and 5 °C using the Wilhelmy plate method. Langmuir adsorption parameters for the organic compounds were extracted by fitting the surface tension data to the Szyszkowski equation. In a mixed organic/salt solution, the surface tension was primarily controlled by the organic component, even when the mass ratio of salt to organic in solution exceeded threefold. Excellent agreement was found between measured surface tension values at 5 °C and those predicted by the Szyszkowski equation using Langmuir adsorption parameters extracted at 25 °C. This finding may have important implications for cloud formation studies where the onset of activation often occurs at temperatures below 25 °C.