Smart CO2 capture and release and an insight into biological evolution based on its characteristics

Since the Industrial Revolution, atmospheric CO2 concentrations have increased, disrupting Earth’s heat radiation balance and contributing to the rise in global mean temperature. This temperature increase naturally accelerates the evaporation of H2O and intensifies climate change. To mitigate climate change effectively, the accumulated atmospheric CO2 concentration must be reduced immediately. Current CO2 capture technologies primarily rely on amines (synthetic organic compounds), but the global adoption of these technologies remains limited. In this context, we recently developed an innovative method utilizing NaOH and CaCl2 to capture and store CO2 by converting it into stable and harmless CaCO3 (the primary component of limestone and coral) through simple chemical reactions. Given CO2’s inherent property of high solubility in water under ambient conditions, the present study was designed to develop a new CO2 capture and release method based on this characteristic. We found that CO2 readily dissolves in water and is easily released when its concentration in the water exceeds that of the surrounding environment. Based on these findings, we propose a smart CO2 capture and release system that uses water as a mediator. Furthermore, increasing the gas pressure and water flow rate enhanced CO2 absorption efficiency, while the addition of NaOH to the water markedly accelerated the absorption process. The proposed system can also be applied to separate CO2 from other gases—such as O2, N2, H2, CH4, and CO—which are nearly insoluble in water. The proposed system operates continuously without a step-wise process and offers a sustainable solution with minimal environmental impact.