RUI: CAS: Nitrate/Nitrite Reduction Utilizing Hemilability and Redox-Activity

Western Washington University, Bellingham WA

Investigators

Abstract

The Chemical Catalysis Program in the Division of Chemistry of the National Science Foundation supports the research project of Professors John Gilbertson and Timothy Kowalczyk at Western Washington University. Their project focuses on developing new ways of addressing pollution caused by fertilizers. While nitrogen-based compounds in fertilizers help crops grow, they can leach into natural waterways, lakes, and oceans fertilizing blooms of algae that deplete the oxygen which is required for other plants to live thus causing “dead zones”. To prevent such dead zones, this research project employes catalysts to remove these nitrogen-containing fertilizers from the water. The research combines computer calculations with laboratory experiments to suggest how these compounds can be converted to less polluting forms. Of particular interest is a new family of iron-based catalysts that are designed to selectively attack the most problematic nitrogen compounds, leaving others unaffected. The new catalysts are being prepared and tested by a team of undergraduate students. This hands-on training provides the scientific skills necessary for technical careers. The laboratory training of the undergraduate researchers is complemented by training in communication and collaboration skills. An extensive set of outreach activities are included, including the construction of a platform for students from diverse backgrounds to engage in scientific discussions across multiple institutional levels. This training facilitates an open dialogue of how research questions are approached and data interpreted. This work delivers benefits to the community through its integration with a complementary pair of science and energy literacy initiatives. Oxoanions play a vital role as the building blocks of living systems. For example, nitrite and nitrate are central to the biogeochemical Nitrogen Cycle. Through human intrusions such as the overuse of fertilizers, the equilibrium/disequilibrium that has historically governed this cycle is changing. With support from the Chemical Catalysis Program in the Division of Chemistry, Professors John Gilbertson and Timothy Kowalczyk at Western Washington University are developing catalysts that integrate hemilability and ligand-based redox activity to study nitrite and nitrate reduction. By developing a family of modular pyridinediimime (PDI) ligands with hemilabile Lewis bases and boron-containing Lewis acids in the secondary coordination sphere, the groups are tuning the sterics, pKa, Acidity Number, and ligand-based reduction potentials for the production of complexes that are redox-matched for NOx- reduction. The project supports undergraduate researchers by providing interdisciplinary scientific and professional training. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.