Facilitated transport behavior of humidified gases through thin-film composite polyamide membranes for carbon dioxide capture

In this work, commercial nanofiltration membranes from the water treatment industry have been shown to give good performance in a carbon dioxide capture application. Permeation of humidified gases through the membrane showed a carbon dioxide permeance of up to 340 GPU and a selectivity of 50, although the performance of a dry membrane with dry gas was significantly lower (6–8 GPU). The permeance of carbon dioxide was dependent on the temperature, pressure and pH of the water used to condition the membranes. The results indicate that a facilitated transport mechanism is dominant when humidified gases are present, probably due to the presence of piperazine functional groups and free amine within the membrane structure. The stability of membrane performance largely depends on the presence of water. This approach has strong potential for commercialisation, as the reliance on a commercial membrane material means that the development pathway can be fast tracked and membrane fabrication costs reduced.

► Commercial nanofiltration membranes showed potential for carbon capture.
► Permeances of up to 340 GPU and selectivity of up to 50 recorded.
► Performance is through a facilitated transport mechanism.
► The membrane must remain hydrated for results to be maintained.