Borate-Catalyzed Carbon Dioxide Hydration via the Carbonic Anhydrase Mechanism

The hydration of CO₂ plays a critical role in carbon capture and geoengineering technologies currently under development to mitigate anthropogenic global warming and in environmental processes such as ocean acidification. Here we reveal that borate catalyzes the conversion of CO₂ to HCO₃^– via the same fundamental mechanism as the enzyme carbonic anhydrase, which is responsible for CO₂ hydration in the human body. In this mechanism the tetrahydroxyborate ion, B(OH)₄^–, is the active form of boron that undergoes direct reaction with CO₂. In addition to being able to accelerate CO₂ hydration in alkaline solvents used for carbon capture, we hypothesize that this mechanism controls CO₂ uptake by certain saline bodies of water, such as Mono Lake (California), where previously inexplicable influx rates of inorganic carbon have created unique chemistry. The new understanding of CO₂ hydration provided here should lead to improved models for the carbon cycle in highly saline bodies of water and to advances in carbon capture and geoengineering technology.