Instantaneous Ex Situ Mineral Carbonation Relevant to Alkali Metals in Clay Nanoparticles

Abstract

Carbon recycling reusing emitted carbon dioxide (CO2) as raw materials is nowadays recognized as a concept ahead of CO2 capture and storage for controlling its emission to the air. Here, recently discovered alkali-metal-based instantaneous ex situ mineral carbonation under ambient conditions is studied for saponite clay nanoparticles. The cationic concentration of Cs+ is varied for seeking the possibility of reusing Cs-contaminated soil in view of carbon recycling. The ex situ mineral carbonation dominantly occurring at the interior surfaces of 10 Å open spaces formed by overlapped nanosheets increases with increasing the Cs concentration up to 0.580 mmol g–1 due to the enlargement of the surface area. The ability of the ex situ mineral carbonation, however, deteriorates with further increasing to 0.585 mmol g–1 since the 10 Å open spaces are effectively occupied by Cs compounds as Cs2O reducing their fraction. The present findings of the ex situ mineral carbonation relevant to the cationic concentration imply that the practical soil associated with a Fukushima nuclear accident can stabilize CO2 without energy consumption as well as chemical solution.