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Research Highlight

Out of Thin Air: Sustainable Separation of Atmospheric CO2

Direct air capture of CO2 via aqueous-phase absorption and crystalline-phase release using concentrated solar power.


Scientific Achievement

A fundamental structural, thermodynamic, and mechanistic study led to the design of a simple system for direct air capture (DAC) of CO2 using environmentally friendly aqueous amino acid sorbents and off-the-shelf equipment, such as an household air humidifier and a solar oven.

Significance and Impact

Negative emission technologies (NETs), i.e. the net removal of greenhouse gases from the atmosphere, are now considered essential for stabilizing the climate. Our DAC approach provides the basis for an energy-sustainable NET and offers the prospect for limiting global temperature rises.

Research Details

First, CO2 absorption is achieved with aqueous amino acid sorbents (glycine, sarcosine) using an air humidifier. The CO2-loaded solutions are then reacted with a guanidine ligand, which crystallizes as a very insoluble carbonate salt (on a par with CaCO3) and regenerates the amino acid sorbents. Finally, effective CO2 release and quantitative regeneration of the guanidine are achieved by heating the carbonate crystals using concentrated solar power.