Effect of temperature on the surface tension of 1-hexanol aqueous solutions.

This paper describes the effect of temperature on the surface tension and adsorption kinetics of 1-hexanol aqueous solutions. The experiments were performed in a closed chamber where both liquid and vapor phases coexisted, and the surface tension was influenced by a combination of liquid and vapor phase adsorption. The surface tension of 1-hexanol aqueous solutions at steady-state was found to decrease upon an increase in temperature, and a linear relationship was observed between them. The modified Langmuir equation of state and the modified kinetic transfer equation were used to model the experimental data of the steady-state and dynamic (time-dependent) surface tension, respectively. The equilibrium constants and adsorption rate constants were evaluated through nonlinear regression for temperatures ranging from 10 to 35 °C. From the steady-state modeling, the equilibrium constants for adsorption from vapor phase and liquid phase were found to increase with temperature. From the dynamic modeling, the adsorption rate constants for adsorption from vapor phase and liquid phase were found to increase with temperature too. Small deviations from the experimental data have been observed in the dynamic modeling. These deviations may be due to the experimental errors or more likely the limitations of the model used.