A BREAKTHROUGH has been made in the manufacturing of carbon nanotube membranes which will lead to large-scale production. These “molecular factories” have the potential to remove carbon dioxide from the air and turn it into fuel.
Membranes designed for filtering small molecules and dissolved salts from water suffer from limitations in their permeability and chemical resistance. Carbon nanotube (CNT) membranes do not have these limitations – for example they have a high permeability – but up until now have been very difficult and costly to produce and have thus remained as prototypes in laboratories.
Mattershift, a startup company based in New York that designs and manufactures nanotube membranes, has developed the ability to mass-produce CNT membranes, which will finally unleash the true potential of this technology.
The carbon nanotube is embedded in a flexible polymer sheet and can be programmed to manipulate molecules in certain ways, making it a programmable molecular gateway. Nanotubes act like a conveyor belt that performs a function on molecules which are passing through in single file. Such processes could be catalysis, desalination of seawater, drug delivery, and purification of pharmaceutical compounds, essentially making the nanotubes into molecular factories. For example, a catalyst gate can be created by affixing a catalyst to the opening of the tube, so that all molecules passing through must interact with the catalyst.
Mattershift’s large-scale CNT membranes match the characteristics and performance of small prototypes. Each polymer sheet is embedded with around 250 trn gateways per square metre, and a series of gateways can be manufactured to have different functions, creating chemical synthesis factories that can be as small as a shoebox.
"It should be possible to combine different types of our CNT membranes in a machine that does what molecular factories have long been predicted to do: to make anything we need from basic molecular building blocks," said Rob McGinnis, Mattershift founder and CEO. "I mean, we're talking about printing matter from the air. Imagine having one of these devices with you on Mars. You could print food, fuels, building materials, and medicines from the atmosphere and soil or recycled parts without having to transport them from Earth."
"Achieving large-scale production of carbon nanotube membranes is a breakthrough in the membrane field," said Benny Freeman, professor of chemical engineering at the University of Texas at Austin. "There's such a large, unexplored potential for carbon nanotubes in molecular separations, and this technology is just scratching the surface of what's possible."
Mattershift will ship its first products later this year to Trevi Systems, developer of water purification systems, for use in a seawater desalination process. "We're excited to work with Mattershift because its membranes are uniquely tailored to allow salts to pass through our system while retaining our draw solute," said John Webley, CEO of Trevi Systems. "We already demonstrated the world's lowest energy desal process in our pilot plant in the UAE last year, and Mattershift's membranes are going to allow us to push the energy consumption even lower."
"This technology gives us a level of control over the material world that we've never had before," said McGinnis. "We can choose which molecules can pass through our membranes and what happens to them when they do. For example, right now we're working to remove CO2 from the air and turn it into fuels. This has already been done using conventional technology, but it's been too expensive to be practical. Using our tech, I think we'll be able to produce carbon-zero gasoline, diesel, and jet fuels that are cheaper than fossil fuels."
Science Advances http://doi.org/cmfp
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