Ionization controls for biomineralization-inspired CO2 chemical looping at constant room temperature

Abstract

Living organisms such as corals can carry out CO₂ looping efficiently via biomineralization under ambient conditions. Inspired by this natural process, we establish a solution system of calcium acetate–ethanol–water (Ca(Ac)₂–C₂H₅OH–H₂O) for CO₂ chemical looping at constant room temperature. The CO₂ capture is achieved by its reaction with Ca(Ac)₂ to form calcium carbonate (CaCO₃) mineral and HAc in the binary solvent with a high C₂H₅OH content. However, an increase in the H₂O content in the system triggers acetic acid (HAc)-induced CaCO₃ dissolution to release CO₂. The system can be recovered for CO₂ capture readily by the replenishment of C₂H₅OH. This biomimetic mineralization-based CO₂ capture/release is controlled by the ionization states of the electrolytes, and is precisely regulated in the C₂H₅OH–H₂O binary solvent. Our attempt highlights the fundamental principle of solution chemistry in reaction control and provides a bioinspired strategy for CO₂ capture/release with very low cost and easy availability.