A textile filter paves the way for eco-friendly carbon capture technology

“Innovation happens when two disciplines of science that don’t usually intersect come together. If you have a foot in both worlds, you’ll notice one thing—it won’t come easily to the others,” Sonia Salmon, associate professor of textile engineering, chemistry and science at NC State in another meaning in an interview.

Salmon points to her expertise in textile engineering and biochemistry. Recently, Salmon and Jialong Shen, a postdoctoral researcher at North Carolina State, created a seemingly simple fabric-based filter that could capture carbon dioxide emissions.

An eco-friendly one at that.

The researchers chose a piece of cheesecloth, known for its many properties, and a naturally occurring enzyme called carbonic anhydrase to create the fabric, whose special property is simply to remove carbon dioxide molecules from the mixture of gases.

Their findings were published in the journal ACS Sustainable Chemical Engineering advance this month.

Their choice of weapon? cotton

Today’s carbon dioxide levels are among the highest seen in the past 800,000 years. According to the National Oceanic and Atmospheric Administration, the fossil fuels that people burn for energy are primarily responsible for the current high concentrations of carbon dioxide.

“I’ve been in this field since 2005. At the time, global carbon dioxide emissions were only 24 billion tons per year. Now it’s greater than 35 billion tons per year. Humans crave energy, and we are getting rid of the byproducts of that energy need – which is CO2 Carbon – it’s far in the air and we don’t collect it. We can’t see it or smell it. It’s very invisible to us, but it’s a very big problem for our planet, and we have to do something about it,” Salmon says.

Their solution was the candidate.

“One of the things we already know about cotton is that it absorbs and transfers water and moisture really well,” she says.

Cotton can also be used to diffuse water into a thin film, creating a very high gas contact area. “When CO2 molecules have to be removed from gas mixtures, the molecule has to come into contact with something—hence the large surface area,” Salmon explains.

Carbon capture inside our bodies?

The researchers chose to model their technology based on an interaction that takes place inside our bodies.

Carbonic anhydrase is an enzyme found in abundance in all mammalian tissues, as well as plants, algae and bacteria. Carbonic anhydrase helps convert carbon dioxide2 and water in bicarbonate (HCO3) And the Protons (H+) (and back again). This process is vital to life and is essential for respiration, digestion, and regulation of cellular pH levels.

According to the researchers, “their enzyme-equipped tissue filters act as a mixture between an air filter and a water filter that performs a chemical reaction at the same time.”

“There are traditional carbon capture systems in operation today that are used in the oil and gas industry – mostly to purify methane and natural gas. When natural gas is taken out of the ground, it is often mixed with carbon dioxide. Therefore, the technology to separate carbon dioxide from the gases It’s already been around for decades,” Salmon explains.

However, most previous systems released carbon dioxide back into the atmosphere. Whereas the idea behind using these filters is to trap gas instead, capture it, which can then be placed underground or converted into valuable products.

“Our technology uses textiles and enzymes to capture CO2 molecules in a very efficient way,” Salmon says.

Sequester carbon dioxide for useful purposes

To create the filter, the enzyme was attached to a two-layer piece of cotton fabric by “dipping” the cloth into a solution containing chitosan, which acts like a glue. According to a press release, the substance traps the enzyme, which then sticks to the tissue.

Then a series of experiments was conducted to find out how efficiently the filter was to separate carbon dioxide from a mixture of carbon dioxide and nitrogen, simulating levels equivalent to those emitted by power plants.

The cloth was rolled into a spiral and pushed into a tube. The researchers pushed the gas through the tube, along with an aqueous solution. When carbon dioxide reacted with water and the enzyme in the solution, it turned into bicarbonate and fell into the filter and tube. Next, they captured the bicarbonate solution and took it out. It can then be used to generate more energy or react with calcium to form limestone.

When the researchers pushed air through the filter at a rate of four liters per minute, they were able to pull out 52.3 percent of the carbon dioxide with a single-stack filter and 81.7 percent with a double-stack filter.

Translation into real applications

While the initial results are exciting, the filter still needs to be tested using the faster air flow rates found in commercial power plants. A comprehensive filtration system will need to process more than 10 million liters of flue gas per minute.

“To tackle this huge problem [Carbon emissions]we were sure that the technology [the one they’re working on] It should be scaled up very quickly,” says Shen in another meaning.

While many carbon capture technologies rely on complex materials, Salmon and Shen chose cotton, which is readily available and can withstand repeated washing, drying, and storage cycles. “Our technology can easily be scaled up using existing textile manufacturing infrastructure,” says Shen.

Researchers are already looking at real-world applications – power plants. “The problem with the technologies currently in use is that it takes a lot of energy to regenerate the solvent, which is expensive,” says Shen. The team intends to use solvents with low regeneration energy, a “cost-effective method that can be deployed at scale.”

Their research is designed based on current technology. “The beauty of our design — the filter — is that it can fall into equipment in power plants,” Salmon says.

Can the modified cloth be worn one day? Can the T-shirt help fight climate change?

“This is more futuristic,” says Salmon. “Our technology helps capture gas particles that have to be stored somewhere. So our system is for something stationary. Unfortunately, you can’t stick it to the back of your car or wear it now. But again with innovation there will be new ways to think about using it.” .

Next in the pipeline

The project received funding from the US Department of Energy, through collaborations with Dr. Min Zhang at the National Renewable Energy Laboratory and Dr. Jesse Thompson at the University of Kentucky’s Center for Applied Energy Research. They were supported by Novozymes, who supplied them with enzymes to work.

“Together with our collaborators, we’ve done some expansion, and hopefully there will be a publication later this year on this work. Frankly, we think the technology is already doing well enough to consider trying to roll it out more widely. But that means building partnerships. With business opportunities. We’re now starting to talk to people about that and we’re looking to make progress,” says Salmon.

Over the past few years, many concepts have been developed to combat climate change. However, many of these never get past the proof-of-concept stage.

Salmon says the energy penalty may have something to do with it.

“Energy is needed for any system to capture carbon. Because you’re fighting to grab gas molecules from the air and pull them into a more concentrated form, that goes against the natural laws of thermodynamics. So you have to pay for energy. In other words, you need to expend some energy from To support carbon capture and storage technology.

The size of this energy penalty was a limiting factor so far.

“There’s also a perception that we’re getting rid of carbon dioxide for free and now we have to pay for it – that’s an obstacle. But, people have to understand that unless we pay for it, our planet is in trouble,” Salmon adds. .

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