Nov. 22 (UPI) -- Scientists have developed a new material, called a metal-organic framework, that successfully captures nitrogen dioxide, or NO2, a toxic pollutant produced by fossil fuel combustion.
The new gas-capturing technology can extract NO2 from the exhaust of a power plant or factory, according to the latest research, published this week in the journal Nature Chemistry. The NO2 captured by the metal-organic framework can be converted easily into nitric acid, which is used to make fertilizer, rocket propellant, nylon and more.
Metal-organic frameworks are metal compounds with three-dimensional lattice structures featuring nano-sized pores. The new framework is called MFM-520, and scientists characterized the shape and size of of its internal pores -- the pockets where NO2 gas becomes trapped -- using neutron scattering and synchrotron X-ray diffraction.
Material scientists can tweak metal-organic frameworks to trap a diversity of compounds. Most metal compounds are designed to remove pollutants, but researchers also have designed frameworks to remove remove salt and metal ions from seawater.
MFM-520 is designed to capture NO2. The material works at ambient pressures and temperatures, and even can trap nitrogen dioxide at low concentrations.
The process for degassing the material, a treatment with water in air, also works to convert the NO2 into nitric acid, a valuable industrial chemical.
"This is the first MOF to both capture and convert a toxic, gaseous air pollutant into a useful industrial commodity," lead study author Sihai Yang, a senior lecturer in chemistry at the University of Manchester in England, said in a news release.
"It is also interesting that the highest rate of NO2 uptake by this MOF occurs at around 45 degrees Centigrade, which is about the temperature of automobile exhausts."
Because the nitric acid market totals more than $2.5 billion, the new technology could prove profitable for producers of the MOF, as well as for industrial sources of NO2.
By studying how exactly the nitrogen dioxide gas molecules move through the material and become trapped, scientists will be better able to tweak metal-organic framework materials for capturing other toxins and pollutants.
"The characterization of the mechanism responsible for the high, rapid uptake of NO2 will inform future designs of improved materials to capture air pollutants," said Jiangnan Li, one of the study's authors and a doctoral student at Manchester.