Experimental and theoretical study of CO₂ adsorption by activated clay using statistical physics modeling

Area of Science:

• Geochemistry
• Materials Science
• Environmental Science

Background:

• Geological storage is a key strategy for mitigating atmospheric carbon dioxide (CO2) levels.
• Activated clay presents a potential adsorbent material for CO2 capture and storage.
• Understanding CO2 adsorption mechanisms on activated clay is crucial for optimizing storage efficiency.

Purpose of the Study:

• To investigate the adsorption behavior of carbon dioxide (CO2) on activated clay.
• To characterize the activated clay material used for CO2 adsorption.
• To develop and interpret a new multi-layer adsorption model for CO2 on activated clay.

Main Methods:

• Clay activation and characterization using scanning electron microscopy, N2 adsorption-desorption isotherms, and X-ray diffraction.
• Generation of CO2 adsorption isotherms at various temperatures (298 K, 323 K, 353 K).
• Simulation and interpretation of adsorption data using a multi-layer model with two interaction energies and physical statistical formalism.

Main Results:

• Physicochemical parameters, including site density (NM) and adsorbed molecules per site (n), were determined.
• Energetic and thermodynamic parameters (internal energy, entropy, Gibbs free energy) of CO2 adsorption were calculated.
• The study confirmed CO2 adsorption on activated clay is a spontaneous and exothermic process.

Conclusions:

• Activated clay is a viable material for CO2 geological storage.
• The developed multi-layer model accurately describes CO2 adsorption behavior.
• The spontaneous and exothermic nature of the adsorption process is favorable for geological storage applications.