MIT offers a means of continuously removing carbon dioxide from a stream of waste gases with a new membrane. The gas permeability of the electrochemically assisted membrane can be switched on and off as needed without the use of mechanical moving parts and with minimal energy consumption.
The membrane is designed to continuously and dynamically modulate gas transfer at a gas-liquid interface. Hexagonal openings allow gas molecules to flow in and out when in the open state, but gas passage can be controlled and blocked using a thin layer of zinc.
A carbon-absorbing material is placed between two switchable gas gating membranes and the device is immersed in propylene carbonate electrolyte solvent to provide a medium for zinc ions to shuttle back and forth. When the sorbent layer is open to the side where the waste gases are flowing, the material readily soaks up carbon dioxide until it reaches its capacity.
This membrane separation device has the potential to eliminate the need for system blowdown between absorption and regeneration, simplify reactor design, improve energy efficiency, and reduce the environmental footprint of separation units.
Image Source: Yayuan Liu et al.