Enhanced mineral carbonation at room temperature through MgO nanocubes synthesized by self-combustion

Abstract

Carbon dioxide is one of well-known greenhouse gases, which cause the global warming and climate change. Mineral carbonation with calcium or magnesium oxide (CaO or MgO) based adsorbents has been investigated to mitigate the impact of climate change on the human health and environment by reducing CO2 concentration in the flue gas and ambient air through adsorption. However, previous studies were generally conducted at higher pressure or higher temperature for applying the adsorbents to the post-capture process. In this study, we synthesized nanometer-sized crystalline MgO particles with a cubic shape (nanocubes) by an aerosol method (Self-combustion), and investigated the adsorption characteristics of the MgO nanocubes at room temperature (25 °C) by comparing with commercial MgO and CaO powders. The CO2 adsorption experiments for the three adsorbents were conducted using a batch type chamber after mixing the adsorbents with deionized water for making slurries. Based on the results of X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA), the MgO nanocubes showed higher captured CO2 per unit mass of the adsorbent than the commercial MgO and CaO adsorbents at the room temperature. Based on the comparison of the ambient hydration and carbonation processes of the two MgO adsorbents, commercial MgO showed similar carbonation kinetics with the commercial CaO. However, the MgO nanocubes showed enhanced carbonation kinetics than the other two commercial metal oxides at room temperature.