Interfacial Tension in Binary Systems Containing a Dense Gas

Abstract

Interfacial tension in binary mixtures consisting of a non-volatile solute (pelargonic acid or stearic acid) and a gaseous component (carbon dioxide, ethane, nitrogen, argon, helium, or hydrogen) has been measured as a function of pressure (up to 25 MPa) and temperature (in the range from 313 to 393 K) using the pendant-drop method. It is shown that the interfacial tension is affected by two factors, namely pressure and the amount of gas dissolved in the liquid phase. While interfacial tension increases with pressure, it decreases with increasing concentration of the gaseous component in the liquid phase which reduces the viscosity. It is further observed that, at a constant temperature and constant mass flow, when a certain pressure is exceeded, a falling film becomes unstable and disintegrates into droplets.