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UND Chemist Mark Hoffman Studying Molecule Interaction in Air Pollution

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The Grand Forks Herald featured the work of University of North Dakota Chemist Mark Hoffman today. Hoffman and his team study chemical reactions at the molecular level using high performance computing models.

UND chemist Mark Hoffmann doesn’t study air pollution, and he doesn’t study the atmospheres of distant worlds — but he can tell you how they work at the molecular level.


What he specializes in is the interaction of molecules, particularly when they’re in an excited state and pumped full of energy, say, in the heart of a coal boiler or at the edge of an atmosphere where solar radiation bombards gas molecules.


These conditions have proven difficult for theoretical chemistry, Hoffmann’s field, but he and his team have developed a new analytical method that can tackle the challenge.


“I’m a physical chemist, chemical physicist, my goal is to understand the nature of chemical bonding, and these are some of the most difficult to understand, least understood types,” he said.


Theoretical chemistry is a discipline that casts aside the test tubes and Bunsen burners for computers and blackboards filled with arcane formulas. It’s useful, Hoffmann said, because it allows scientists to understand interactions where experimentation is impractical or impossible.


The sodium-sulfur compounds in the atmosphere of Io, a moon of Jupiter, are too far away. The hydroperoxyl radicals released from burning coal are too elusive, appearing and disappearing in the wink of an eye. But they can all be simulated in UND’s mainframe.


Hoffmann believes many applications await, such as better ways to scrub the exhaust from coal power plants and better understanding of alien worlds.


His team’s paper, “On the inclusion of triple and quadruple electron excitations into MRCISD with multiple states,” was the featured article in Chemical Physics Letter last month. The co-authors were Yuriy G. Khait, an adviser to the Russian Scientific Center, and Wanyi Jiang, a research associate at the University of North Texas.



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It so happens that his team’s method is adept at analyzing chemical interactions that other methods have a hard time with, such as those involving combustion and radiation. This is a cause of some excitement for Hoffmann because it means that some light can be shed on the elusive hydroperoxyl radicals, or O2H.


O2H is “extraordinarily reactive,” and it interacts with other molecules by breaking them apart and allowing them to recombine, he said. It’s just “havoc.”


So, an ordinarily benign molecule of oxygen, O2, turns into ozone, O3. According to the U.S. Environmental Protection Agency, ozone can irritate lung tissue, cause inflammation and, in severe cases, cause permanent damage.



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What an engineer could do with the knowledge of chemical interactions during combustion is design a process to neutralize the pollutants or make them less harmful, he said. One real world example of that, he said, is mercury, a pollutant in coal combustion. Mercury is hard to capture in its pure form, he said, but when it’s oxidized, combined with oxygen, it can be captured much easier.

Hoffmann isn’t always satisfied with leaving practical applications of his work to others, either. He’s now collaborating with experimental chemists to develop catalysts that would work well with biological feedstocks, such as vegetable oil.

Catalysts separate feedstocks into different components for use in everything from gasoline substitutes to plastics, but the ones in use in the petroleum industry don’t work very well with bio feedstocks.

Because these sorts of chemical interactions can involve thousands upon thousands of electrons, even approximation methods are overwhelmed. Experimental chemistry is in its element here because chemists need only mix the chemicals, let nature figure out the interactions and observe.

Read the full article.

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