Theory of Interfacial Tension of Partially Miscible Liquids

TL;DR

This paper investigates the relationship between interfacial tension and surface tensions of pure liquids, revealing the limitations of existing empirical formulas and proposing a new theoretical equation.

Contribution

It critically analyzes the empirical Girifalco-Good formula and introduces a new theoretical relation between interfacial and surface tensions.

Findings

Existing empirical formula has weaknesses.

A new theoretical relation is proposed.

Physical correlation between interfacial and surface tensions is limited.

Abstract

The aim of this work is to study the problem of the existence of a fundamental relation between the interfacial tension of a system of two partially miscible liquids and the surface tensions of the pure substances. It is shown that these properties cannot be correlated from the physical point of view. However, an accurate relation between them may be developed using a mathematical artifact. In the light of this work, the basis of the empirical formula of Girifalco and Good is examined. The weakness of this formula as well as the approximation leading to it are exposed and discussed and, a new equation connecting interfacial and surface tensions is proposed.