Effects of viscosity on dynamic interfacial tension.

Abstract

In this study, we have investigated the interfacial tension (IFT)-lowering potential of a range of caustic solutions which were contacted with dilute solution of linoleic acid in light paraffin oil. Two polymers, namely, polyvinyl alcohol and polyacrylamide were added to the caustic solution in order to increase bulk phase viscosity. The dynamic IFT of caustic, polymer and caustic-polymer solutions were measured. By using different linoleic acid concentrations up to 100 mM, it was found that an increase in acid concentration was accompanied by a decrease in IFT for any given caustic composition. When the acid strength was fixed at 10 mM and the caustic concentration was also increased up maximum of 250 mM, the lowest IFT values were obtained at 12.5 mM NaOH. The dilute polymer solutions lowered the IFT of the oleic phase against neutral water from 30.0 to about 15 mN/m. However, the addition of the polymeric material to the caustic solution produced a marginal reduction in dynamic IFT at early contact times and also produced characteristic IFT minima at all caustic concentrations. (Abstract shortened by UMI.)