Adsorption of CO₂ on Vermiculite-Derived Samples

Area of Science:

• Materials Science
• Environmental Chemistry
• Adsorption Science

Background:

• Vermiculite, a clay mineral, possesses potential for carbon dioxide (CO2) adsorption.
• Its inherent physicochemical properties limit its efficiency for CO2 capture.
• Acid modification is explored as a strategy to enhance vermiculite's adsorption capabilities.

Purpose of the Study:

• To improve the physicochemical properties of vermiculite for enhanced CO2 adsorption.
• To investigate the structural changes in vermiculite after acid treatment.
• To evaluate the CO2 adsorption performance of acid-modified vermiculite.

Main Methods:

• Vermiculite samples were treated with nitric acid (HNO3), hydrochloric acid (HCl), and a mixture of both.
• Characterization techniques included X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Fourier-Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Transmission Electron Microscopy (TEM), and nitrogen physisorption.
• CO2 adsorption was measured at 1 bar and temperatures of 0°C, 20°C, and 30°C.

Main Results:

• Raw vermiculite showed a low CO2 uptake of 25.91 mg g⁻¹ due to limited surface area and pore volume.
• The vermiculite treated with 3 M HNO3 exhibited the highest CO2 adsorption capacity, reaching 70.48 mg g⁻¹.
• Acid modification significantly improved the CO2 adsorption capacity of vermiculite.

Conclusions:

• Acid treatment is an effective method for enhancing the CO2 adsorption performance of vermiculite.
• The Sips model best described the CO2 adsorption isotherms for acid-activated vermiculites.
• Both chemical composition and textural properties are critical for CO2 adsorption efficiency.