Source :A research team in Fukuoka Prefecture, Japan, has succeeded in removing nitrogen oxides (NOx) from exhaust emissions with a special type of carbon fibers. In the demonstration test in October 2003, more than 90 percent of nitrogen monoxide was removed from exhaust fumes. The result is attracting worldwide attention. The research team was made up of two groups of researchers: one led by Dr. Takaaki Shimohara at the Fukuoka Institute of Health and Environmental Science, and the other by Dr. Isao Mochida at the Institute of Advanced Material Study of Kyushu University.
The activated carbon fibers are extremely fine and have numerous microsopic pores on their surface, giving them a huge surface area despite their small volume. In the test, atmospheric NOx was either absorbed by the activated carbon fibers or decomposed into nitrogen gas and water.
Other options are also available to remove NOx emissions, such as photocatalysis systems using titanium dioxide or soil filter systems. They are, however, not efficient enough to remove atmospheric NOx, and do require maintenance costs and time.
By contrast, activated carbon fibers efficiently clean up the air with little maintenance expense and their production cost is low. The fibers can be easily processed into any compact design. They are also reusable after being calcined at 200 degrees Celsius, because absorbed NOx comes off from the surface under these conditions. Expected applications include walls along highways and in underground parking lots.