Near Equilibration Times in the Diffusion-Controlled Adsorption

Area of Science:

• Physical Chemistry
• Surface Science
• Chemical Engineering

Background:

• The Frumkin isotherm describes adsorption, considering interactions between adsorbed molecules.
• Understanding adsorption dynamics is crucial for processes involving interfaces.

Purpose of the Study:

• To develop a model for calculating the time to reach near-equilibrium adsorption (99% coverage).
• To analyze the influence of bulk concentration and molecular attraction on adsorption kinetics.

Main Methods:

• Mathematical modeling of adsorption kinetics on a rotating disk surface.
• Incorporation of the Frumkin isotherm equation to account for intermolecular forces.

Main Results:

• Near-equilibrium time is dependent on bulk surfactant concentration and molecular attraction.
• A sharp spike in equilibration time occurs near the isotherm's inflection point.
• This spike is attributed to a slow initial flux followed by a drastic increase.

Conclusions:

• The developed model quantifies adsorption near-equilibrium times.
• Molecular attraction significantly impacts adsorption kinetics, especially near inflection points.
• The study highlights the complex interplay between flux, surface coverage, and isotherm behavior.