Adsorption and Desorption Kinetics with Systems Having a Concentration-Dependent Coefficient of Diffusion

Area of Science:

• Adsorption science
• Chemical engineering
• Materials science

Background:

• Surface diffusion is a key transport mechanism in many adsorbent materials.
• The rate of surface diffusion can be influenced by the concentration of adsorbate.
• Understanding these transport phenomena is crucial for optimizing adsorption processes.

Purpose of the Study:

• To develop and solve model equations for adsorption and desorption processes.
• To account for both bulk diffusive-convective mass transfer and surface diffusion.
• To derive equations for key parameters governing these processes.

Main Methods:

• Solving model equations for adsorption and desorption, considering both bulk and surface transport.
• Analyzing a range of parameter values applicable to various adsorption systems.
• Deriving analytical expressions for critical kinetic and thermodynamic parameters.

Main Results:

• Derived equations for the surface diffusion coefficient (Di).
• Derived equations for the activation energy of surface diffusion (-ΔH).
• Derived equations for relaxation times and times to reach quasi-equilibrium for adsorption and desorption.

Conclusions:

• The study provides a framework for quantifying surface diffusion in adsorption systems.
• The derived equations enable calculation of key parameters for process optimization.
• This work contributes to a deeper understanding of mass transport in adsorbents.