Kinetics of Surfactant Adsorption at Fluid/Fluid Interfaces: Non-ionic Surfactants

TL;DR

This paper develops a comprehensive model for the kinetics of surfactant adsorption at fluid interfaces, incorporating diffusion and interfacial kinetics, and provides a method to calculate dynamic surface tensions, with findings on non-ionic surfactants' diffusion-limited adsorption.

Contribution

It introduces a unified free-energy based model that captures both diffusion and interfacial kinetics for soluble surfactants, enabling calculation of dynamic surface tensions.

Findings

Non-ionic surfactants generally undergo diffusion-limited adsorption.

The model aligns with experimental observations.

Provides a general method for dynamic surface tension calculation.

Abstract

We present a model treating the kinetics of adsorption of soluble surface-active molecules at the interface between an aqueous solution and another fluid phase. The model accounts for both the diffusive transport inside the solution and the kinetics taking place at the interface using a free-energy formulation. In addition, it offers a general method of calculating dynamic surface tensions. Non-ionic surfactants are shown, in general, to undergo a diffusion-limited adsorption, in accord with experimental findings.