Dealing with nuclear waste is a major problem for all countries with nuclear power plants. A discovery at Indiana University could help solve the problem.
I.U. researchers published a report in the journal Chem on September 14th that detailed their development of a “new chemical principle.” They say that this principle has the potential to create special molecules that can remove radioactive elements from nuclear waste. This would significantly reduce the volume of such waste. The method can also be applied to the creation of molecules that could extract chemical pollutants from water and soil.
The lead author of the report is Amar Flood who is a professor of Chemistry at the I.U. Bloomington College of Arts and Sciences. He said, "This work represents a major step forward in the effort to engineer specially designed nanostructures by providing a new, highly accurate method to predict how these molecules will behave in solution."
Predicting how an engineered molecule will behave in the real world has been nearly impossible. Currently, chemists can only design molecules to function isolation. In the real world, they will wind up in combination with other molecules. The behavior of the molecule in isolation will often be quite different than its behavior in combinations of molecules. When designing a molecule for a specific purpose, the designer has to be extremely precise. It is sort of like designing a key for a specific lock.
Flood’s lab designed a special five sided star shaped lattice of carbon and nitrogen atoms. The center of the molecule is empty. The shape of the hole attracts negative molecules such as phosphates and nitrates which lock into the center hole and break their previous bonds.
This type of special molecule is known as a “receptor” molecule. It is intended for use in the reduction of nuclear waste. It is also being considered for such uses as removing chlorine atoms from water which plays a part in desalinization of seawater. It could be used to remove excess fertilizers from solid. Lithium atoms could be recovered from soil for use in electronics.
The new methods described in the report will allow chemists to design new molecular reactions with a specific goal in mind. The new principle elucidated in the report makes use of the discovery that the attraction between receptor molecules and negatively charged ions turns out to be related to the dielectric constant of the solvent which contains the two species of molecules. (“A dielectric constant is a measurement of a substance's ability to stabilize electrical charge.”)
In a test of their new method, the researchers applied it to trazolophane. This molecule is designed to extract chloride from other molecules. It is used in combination with solvents that are commonly used to extract targeted molecules from other liquids. In each test, the new principle accurately predicted how effective the molecule would be.
The scientist who was primarily responsible for the discovery of the new principle was Yun Liu, one of Flood’s Ph.D. students. He said, "The current paradigm only works for molecular designs on the drawing board. But we want to make molecules that will work in practice to help solve problems in the real world."
