Researchers have developed a new membrane technology that allows for more efficient removal of carbon dioxide (CO2) from mixed gases, such as emissions from power plants.
“To demonstrate the capabilities of our new membrane, we looked at a mixture of CO2 and nitrogen, as the CO2/nitrogen dioxide mixture is very relevant in the context of reducing greenhouse gas emissions from power generation,” said Rich Spontak, the correspondent author of the working paper. “And we have shown that we can greatly increase the selectivity of the membrane for removing CO2 while maintaining a relatively high CO2 permeability.”
“We’re also looking at a mixture of CO2 and methane, which is important for the natural gas industry,” said Spontak, who is Distinguished Professor of Chemical and Biomolecular Engineering and Professor of Materials Science & Engineering at North Carolina State University. “Additionally, this CO2 filtering membrane can be used in any situation where one needs to remove CO2 from a gas mixture — whether it’s a biomedical application or scrubbing CO2 from the air on a submarine.”
Membranes are an attractive technology for removing CO2 from mixed gases because they do not take up much physical space, can be made in various sizes, and are easy to replace. Another technology often used to remove CO2 is chemical adsorption, which involves bubbling the gas mixture through a column filled with liquid amines — which removes CO2 from the gas. However, absorption technology has a much larger footprint, and liquid amines tend to be toxic and corrosive.
These membrane filters work by allowing CO2 to pass through the membrane faster than any other constituent in the mixed gas. As a result, the gas leaving the other side of the membrane has a higher proportion of CO2 than the gas entering the membrane. By capturing the gas escaping the membrane, you capture more CO2 than any of the other constituent gases.
The long-standing challenge for such membranes has been trade-off between permeability and selectivity. The higher the permeability, the faster you can move gases through the membrane. But as the permeability goes up, the selectivity goes down — meaning nitrogen, or other elements, also pass through the membrane quickly — reducing the ratio of CO2 to other gases in the mixture. In other words, when the selectivity drops, you capture relatively less CO2.
The research team, from the US and Norway, addressed this problem by growing hydrophilic and CO2-philic chemically active polymer chains on the surface of the existing membrane. This increases the selectivity of CO2 and causes a relatively small decrease in permeability.
“In short, with a slight change in permeability, we have shown that we can increase the selectivity by about 150-fold,” said Marius Sandru, co-author of the paper and senior research scientist at SINTEF Industry, an independent research organization in Norway. “So we’re capturing more CO2, compared to other species in the gas mix.”
Another challenge facing membrane CO2 filters is cost. The more effective the previous membrane technology, the more expensive it will be.
“Because we wanted to create a commercially viable technology, our technology started with membranes that are already widely used,” said Spontak. “We then engineered the surface of these membranes to increase selectivity. And while this increases costs, we think the modified membranes will remain cost-effective.”
“Our next step is to see to what extent the techniques we have developed here can be applied to other polymers to obtain comparable, or even superior results; and to improve the nanofabrication process,” said Sandru. “To be honest, although the results here are very interesting, we have not tried to optimize this modification process. Our paper reports the results proof-of-concept.”
The researchers are also interested in exploring other applications, such as whether the new membrane technology could be used in biomedical ventilator devices or filtration devices in the aquaculture sector.
The researchers say they are open to working with industry partners on exploring these questions or opportunities to help mitigate global climate change and improve device functionality.
(Materials provided by North Carolina State University)
***
Solo, Sunday, April 10, 2022. 1:25 pm
‘warm greetings full of love’
Suko Waspodo
–
Ordinary Man
–
–
–
-“).attr({
type: ‘text/javascript’,
src: ‘https://platform.twitter.com/widgets.js’
}).prependTo(“head”);
if ($(“.instagram-media”).length > 0)
$(”
