General Adsorption Model to Describe Sigmoidal Surface Tension Isotherms of Binary Liquid Mixtures.

Surface tension (σ) isotherms of liquid mixtures can be divided into Langmuir-type (L-type, including L- and L-type) and sigmoid-type (S-type, including S- and S-type). Many models have been developed to describe the σ-isotherms. However, the existing models can well describe the L-type isotherms, but not the S-type ones.