Chemist Discovers the Elusive Chemical Middleman That Removes Acid Rain

August 29, 2008,

(PhysOrg.com) -- Researchers have discovered the middleman in the complex chemical reaction that is essential to the atmosphere's ability to break down pollutants, especially the compounds that cause acid rain. The study improves the basic understanding of the chemical removal of acid rain and will allow scientists to better model how pollutants are removed from the atmosphere and to predict potential environmental conditions.

The first identification of OH-HONO2 within this chemical reaction was performed by Marsha Lester, chair of the Department of Chemistry in the School of Arts and Sciences at the University of Pennsylvania and Joseph Francisco, professor of chemistry at Purdue University.

The molecule, speculated as the possible middleman, has eluded detection by scientists for more than 40 years. The breakthrough was provided by an improved experimental methodology that used direct spectroscopic characterization of the chemical, like an infrared fingerprint; this was the first time researchers employed a technique sensitive enough to observe the presence of the chemical. Complementary theoretical calculations performed with supercomputers validated the spectral signature of this novel molecule.

The paper, published in a special edition of the Proceedings of the National Academy of Science, showed for the first time all the steps the Earth’s atmosphere takes in oxidizing pollutants, akin to the human body’s ability to metabolize food.

"We've speculated about this unusual atmospheric species for many years, and then to actually see it and learn about its properties was very exciting," said Lester.

"The chemical details of how the atmosphere removes nitric acid have not been clear," Francisco says. "This gives us important insights into this process. Without that knowledge we really can't understand the conditions under which nitric acid is removed from the atmosphere."

An unusual aspect of the molecule helped it escape detection by scientists. The reaction involving this molecule proceeds faster as you go to lower temperatures, which is the opposite of most chemical reactions," said Lester. "The rate of reaction also changes depending on the atmospheric pressure, and most reactions don't depend on external pressure. The molecule also exhibits unusual quantum properties.”

What makes the molecule of interest to basic chemistry as well as an understanding of the environment is its two hydrogen bonds. The two bonds enable the molecule to form a six-sided ring structure. Normally weaker than covalent bonds, the two hydrogen bonds are strong enough to affect atmospheric chemistry. These bonds may tell science more about biological systems that depend on hydrogen bonds.

Provided by University of Pennsylvania

Explore further: New process allows 3-D printing of nanoscale metal structures

Related Stories

'Chemical net' could be key to capturing pure hydrogen

January 29, 2018

Hydrogen is one of the most abundant elements on Earth and an exceptionally clean fuel source. While it is making its way into the fuel cells of electric cars, busses and heavy equipment, its widespread use is hampered by ...

Chemists make bicycle-like molecular drive

February 7, 2018

Molecular cars have been known for some time, but scientists from the University of Amsterdam's Van 't Hoff Institute for Molecular Sciences (HIMS) and the University of Murcia have now synthesized molecules that operate ...

A bacterial powder for quickly stabilizing gravel surfaces

January 23, 2018

EPFL's Laboratory of Soil Mechanics has developed an easily reproducible technique using bacteria and urea to reinforce sandy or gravelly terrain. A series of chemical reactions lead to the rapid formation of mineral crystals ...

Recommended for you

Researchers find tweeting in cities lower than expected

February 20, 2018

Studying data from Twitter, University of Illinois researchers found that less people tweet per capita from larger cities than in smaller ones, indicating an unexpected trend that has implications in understanding urban pace ...

Reaching new heights in laser-accelerated ion energy

February 20, 2018

A laser-driven ion acceleration scheme, developed in research led at the University of Strathclyde, could lead to compact ion sources for established and innovative applications in science, medicine and industry.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.