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

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