Editor’s note: After reporting on a Summit County based company that’s producing nanofibers for pollution-control devices, I realized that I didn’t completely understand how the process works. I asked MemPro CEO John Finley to provide an explanation. He responded within 24 hours with the following explanation.
One of the main benefits of nano products is the concept of surface area.
The first idea about surface area is demonstrated by a small bundle of angel hair pasta. A bundle of pasta (for one serving before cooking) has a diameter of .81 inch and a length of 10 inches. This bundle of pasta has an outside surface area of 25.4 square inches (.81 x 10.0 x 3.14 = 25.4). A single piece of pasta from that uncooked bundle has a surface area of 1.1 square inch (.03 x 10.0 x3.14 = 1.1).
But there are 225 of them in the bundle, so when the pieces of pasta are put end-to-end they have a combined surface area of 240 square inches. From this example we can see that many small fibers have more surface area than one large fiber. In the case of angel hair pasta the individual pasta pieces have a combined surface area of more than times times the surface area of the bundle.
The other idea behind the surface area of our fibers has to do with the structure of the fibers themselves. When our nanofibers are magnified many thousands of times, sections of our fibers look like cholla cactus wood. Keep in mind that our fibers are miles long, but small sections of our fiber would look like the cholla cactus wood pieces pictured here:
Cholla cactus wood has lots of surface area, and we can think of its surface area as any place air can touch the piece of wood. So looking at the picture, it is clear that air can surround and touch the outside of the wood as well as pass through and contact the inside surfaces. Compared with a solid piece of wood (like pine, for instance), cholla cactus wood has much more surface area, because of all the inside surfaces.
When we make ceramic nanofibers we start with chemistry. By mixing certain polymers (plastics) together with ceramic compounds and with catalyst chemicals (precious metal compounds), we end up with fibers that have catalyst metal particles embedded on the surface of the fibers. Thinking about the idea of large surface area in small things brings us to the conclusion that a small amount of catalyst metal goes a long way when put on the surface of our fibers.
And because our fibers are so open – we call them “mesoporous” – they do a highly effective job of making contact with gaseous pollutants like engine exhaust. Contact between poisonous gases from engines and catalysts (usually platinum, palladium and rhodium) allows the catalysts to do the job of changing the poisonous gas into something safe. Examples of this are Nitrogen Oxides (NOx) which are produced when gasoline and diesel fuels are burned. Catalysts help NOx break down into oxygen (O2) and nitrogen (N2), which are safe to breathe and major components of air.
That is the story about catalyzed ceramic nanofibers (our nCATfiber™ material) as applied to engine exhaust. Fortunately our fibers also help in all kind of chemical reactions, like the making of pharmaceuticals and fine chemicals. The theory of surface area and the reactivity of the catalyst particles is the same. Just another large market for us to go after.