Capturing CO2 emissions with sawdust and solar energyS. Himmelstein | December 14, 2021
A low-energy approach to a reversible carbon dioxide capture strategy has been demonstrated by researchers from Renmin University of China. Solar radiation serves as the energy source and modified sawdust is used as the CO2 absorbent in a system that enables use of the captured gas to generate methanol, ethanol and other products.
The CO2 adsorbent, based on sawdust impregnated with an aqueous solution of low-molecular-weight amine-based polymer, does not require complicated synthesis and can trap CO2 and be regenerated by solar heating. A reflector and sunlight absorption layer formed the sunlight harvesting system applied to heat the modified sawdust.
In a proof-of-concept demonstration, a mixed gas consisting of CO2 and nitrogen was treated by the sawdust-solar harvesting system. Half of the CO2 in the mixed gas was rapidly extracted by the separation process within 6 minutes. The CO2 concentration fell from 30.1% to 2.7% under a continuous illumination of solar light for 120 minutes, and 91% of CO2 inside the test gas tank was successfully captured by sawdust. The target gas was also reversibly discharged from the separation system, thus renewing the sawdust as fresh CO2 absorbent.
The research is published in Green Energy & Environment.