Dimensional Effects in Interfacial Tension Micro-Scale Measurements

Three different experimental configurations to measure oilwater interfacial tension (IFT) are developed using micropipet manipulation technique. By applying the minimum suction pressure required for the interface to flow in a micro-size pipet, IFT is calculated using Young-Laplace equation by achieving mechanical equilibrium condition for the two liquids separated by an interface. The three different configurations produced similar results for critical pressure measurements versus pipet diameter. IFT measurements using micropipet technique found to fall within two regimes: geometry-dependent regime and geometry-independent one. The notion of geometry-dependent IFT seemingly rises from the presence of a layer of an “ultra-structured” liquid exists near the solid surface. The layering effect appears to vanish at a pipet diameter of 40 μm, which is only applicable only to the present system comprised of crude oil, water, and glass. The IFT value obtained in the geometric-dependent regime is found to be in a good agreement with the value obtained from spinning droplet technique.