Efficient CO₂ adsorption using chitosan, graphene oxide, and zinc oxide composite

Area of Science:

• Materials Science and Engineering
• Environmental Science and Technology
• Chemical Engineering

Background:

• Growing concerns about atmospheric carbon dioxide (CO2) levels necessitate the development of efficient CO2 capture technologies.
• Composite materials offer tunable properties for enhanced adsorption performance.
• Chitosan (CTS), graphene oxide (GO), and zinc oxide (ZnO) are explored for their potential in CO2 adsorption.

Purpose of the Study:

• To synthesize and characterize a novel CTS/GO/ZnO composite for efficient CO2 adsorption.
• To optimize the CO2 adsorption process using Design of Experiments (DOE) based on Response Surface Methodology (RSM) with a Box-Behnken Design (BBD).
• To investigate the adsorption mechanism, kinetics, and thermodynamics, and assess the adsorbent's reusability.

Main Methods:

• Synthesis of CTS/GO/ZnO composites with varying GO and ZnO loadings.
• Volumetric adsorption setup to measure CO2 uptake under different temperatures (25-65 °C) and pressures (1-9 bar).
• RSM-BBD for experimental design and optimization; isotherm, kinetic, and thermodynamic modeling.

Main Results:

• Optimized composite (23.8 wt% GO, 18.2 wt% ZnO) achieved a maximum CO2 uptake of 470.43 mg/g at 30.1 °C and 8.6 bar.
• Freundlich and fractional order models best described the adsorption isotherms and kinetics, respectively (R² = 0.99).
• Thermodynamic analysis indicated an exothermic, spontaneous, and physisorption process (ΔH° = -19.121 kJ/mol, ΔG° = -9.608 kJ/mol).
• The adsorbent exhibited good robustness with only a 4.35% loss in efficiency after ten regeneration cycles.

Conclusions:

• The developed CTS/GO/ZnO composite is a highly efficient and regenerable adsorbent for CO2 capture.
• The study successfully optimized the adsorption process parameters using RSM-BBD.
• The findings support the potential of this composite for industrial CO2 capture applications.