On the Calculation of Liquid–Vapor Interfacial Thickness Using Experimental Surface Tension Data

Abstract

In this paper we investigate the vapor–liquid interfacial thickness of several pure fluids using a new method. In this method, the surface thickness is obtained using experimental surface tension data, and its dependence on the temperature is evaluated. The interfacial width is found to increase with increasing temperature and goes to infinity when the temperature approaches its critical value. Also, we find that a plot of ln δ versus ln {(1−Tr)−1} is linear, in which δ and Tr are the interfacial thickness and reduced temperature, respectively. In this method, the equation of state obtained from the Statistical Associating Fluid Theory (SAFT EOS), which is molecular based, is accepted.