Counter-Intuitive Magneto-Water-Wetting Effect to CO₂ Adsorption at Room Temperature Using MgO/Mg(OH)₂ Nanocomposites

Abstract

MgO/Mg(OH)2-based materials have been intensively explored for CO2 adsorption due to their high theoretical but low practical CO2 capture efficiency. Our previous study on the effect of H2O wetting on CO2 adsorption in MgO/Mg(OH)2 nanostructures found that the presence of H2O molecules significantly increases (decreases) CO2 adsorption on the MgO (Mg(OH)2) surface. Furthermore, the magneto-water-wetting technique is used to improve the CO2 capture efficiency of various nanofluids by increasing the mass transfer efficiency of nanobeads. However, the influence of magneto-wetting to the CO2 adsorption at nanobead surfaces remains unknown. The effect of magneto-water-wetting on CO2 adsorption on MgO/Mg(OH)2 nanocomposites was investigated experimentally in this study. Contrary to popular belief, magneto-water-wetting does not always increase CO2 adsorption; in fact, if Mg(OH)2 dominates in the nanocomposite, it can actually decrease CO2 adsorption. As a result of our structural research, we hypothesized that the creation of a thin H2O layer between nanograins prevents CO2 from flowing through, hence slowing down CO2 adsorption during the carbon-hydration aging process. Finally, the magneto-water-wetting technique can be used to control the carbon-hydration process and uncover both novel insights and discoveries of CO2 capture from air at room temperature to guide the design and development of ferrofluid devices for biomedical and energy applications.

Keywords

• room temperature
• CO₂ adsorption
• magneto-wetting
• nesquehonite
• aging