This paper investigates how expansion and compression of the surface of a drop containing an organic compound, 1-octanol, affect surface tension. The experiments were performed in a closed chamber where the effect of 1-octanol concentrations in both liquid and gas phases on the surface could be studied. The concentration of 1-octanol varied from 0.2 mM to 2.92 mM (about 70% of it's water solubility). Experiments showed surface tension decreased upon compression and increased upon expansion. In expansion when the drop's concentration (at water environment) was greater than 0.5 mM and when the change in surface area of the liquid phase was greater than 5%, the surface tension of the drop exhibited a rapid decrease followed by a gradual increase, back to the "equilibrium" value prior to the expansion. For this case, using Buckingham theorem, a dimensionless parameter was derived and a regression model was fitted to the experimental results of response time delay (the ...
A. Firooz, P. Chen