Synthesis, characterization, CO2 mineralization in air, and thermal decomposition of nano- C8H10MgO10·4H2O powder.

Effective solutions for efficient carbon dioxide (CO2) capture in air at room temperature are in high demand due to the major impacts CO2 has on global climatic changes. Solid adsorbents materials for CO2 capture received great attention over the past years, among them, magnesium-based sorbents have been identified as a promising solution for CO2 capture at intermediate temperatures. This study reports for the first time (1) the synthesis of monoclinic magnesium malate tetrahydrate by combining electrospinning and aging processes, and (2) its room temperature CO2 adsorption and mineralization in air. Commercial magnesium hydroxide (Mg(OH)2) powder was used as raw material in the synthesis of magnesium carbonate hydrates (MCH), by three processes; (1) direct calcination, (2) electrospinning and calcination, and (3) electrospinning, calcination, and aging (at room temperature and in air to incubate CO2 mineralization). The synthesized powder samples were characterized thoroughly using XRD, SEM, EDS, and TGA analyses. Effects of calcination temperature/aging time on CO2 adsorption (at room temperature), crystallization, and mineralization of MCH were studied. Interestingly, the results showed that the 6-month aged samples (via the third synthesis process above), recorded a CO2 adsorption capacity of 15.5 wt% within 90 min at 30 °C. Subsequently, three novel mechanisms of thermal decomposition CO2 adsorption/mineralization were proposed, and a theoretical upper limit of carbon saving potentials was estimated, i.e., 8 mol CO2 per 1 mol MgO. This work provides a novel CO2 mineralization approach that results in (1) effective and practical solutions of carbon dioxide (CO2) emission management and which holds (2) great potential for novel carbon-based fuels development.