PRESSURE-DEPENDENCE OF INTERFACIAL-TENSION OF HYDROCARBON WATER-SYSTEMS USING AXISYMMETRICAL DROP SHAPE-ANALYSIS

A number of theories suggest that the pressure (P) dependence of interfacial tension (gamma) (the slope of the gamma-P curve) is related to the thickness of the liquid-fluid interface. High quality data in this area are scarce; thus testing such theories is difficult. However, with the advent of ADSA (axisymmetric drop shape analysis), gamma and hence its pressure coefficient can be measured with much greater accuracy than the more traditional methods were capable of. A study was undertaken using ADSA to determine both the time and pressure dependences of interfacial tension for the pure n-decane-water system in the 0-35 MPa pressure range. The results indicate that the gamma-P relationship is highly linear and that the pressure coefficient for this system at 21.2-degrees-C is (22.37 +/- 0.35) x 10(-12) m, while at 21.5-degrees-C this value increases to (23.29 +/- 0.48) x 10(-12) m.