In-situ capture and conversion of atmospheric CO₂ into nano-CaCO₃ using a novel pathway based on deep eutectic choline chloride-calcium chloride

This study presents a newfangled method and provides a new approach toward capturing-entrapping the toxic and harmful greenhouse gas CO₂ and subsequently employing it as a useful precursor for the production of value-added calcite (CaCO₃) nanoparticles. All the processes are done in a single system (one-pot and in-situ processing) based on deep eutectic choline chloride-calcium chloride (Calcoline) at mild temperature of 50 °C in direct contact with air. The Calcoline eutectic mixture shows the calcite production yield of 6.2 mg/ml that is reduced up to 22.6% upon recycling. The eutectic mixture provides an interesting all-in-one system acting as carbon dioxide trapper/adsorbent, solvent to solubilize CO₂, and reagent to convert solubilized CO₂ into pure calcite nanoparticles with average particle size of 30 nm. The featured properties of the developed method including simplicity, recyclability, mobility, affordability, and sustainability make it feasible for large scale applications by which the simultaneous elimination of CO₂ from the environment and conversion of it into value added nano-products will be practicable.