Carbon Dioxide Capture in Homogeneous and Heterogeneous Surfaces of Porous Silica Glass

• Main Authors: Chontira Boonfung, Chaiyot Tangsathitkulchai, Atichat Wongkoblap
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: Processes
• Subjects: adsorption; carbon dioxide capture; defective surface; Grand Canonical Monte Carlo; porous silica glass; surface functional groups
• Online Access: https://www.mdpi.com/2227-9717/8/10/1260
• ISSN: 2227-9717

Experimental and simulation studies for carbon dioxide (CO₂) adsorption on porous silica glass were performed to reveal how surface heterogeneity can affect the adsorption mechanism of CO₂. In performing the simulation, the structure of porous silica glass was modeled as a slit pore consisting of parallel walls of connected SiO₄ units. The adsorption isotherms of CO₂ at 283 K were generated for a series of pore widths using a Monte Carlo ensemble. The defective surfaces created by random removal of surface atoms and the surfaces containing hydroxyl functional groups were chosen to represent the surface heterogeneity for the simulation tasks. The isotherms derived for the defective surfaces showed a rapid adsorption at low pressures because of the stronger interaction between the rough nonuniform surfaces and CO₂ molecules. For the role of surface functional groups, the adsorption isotherms dramatically increased with an increasing number of functional groups. The amount of CO₂ adsorbed for randomly placed functional groups was greater than that for the presence of functional groups at the pore edges. The proper control of surface heterogeneity by manipulating both the amounts of hydroxyl surface groups and surface defects should help enhance the efficient capture of CO₂ in porous silica glass.