The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.
This award will support a twenty-four-month research fellowship by Dr. Jennifer J. Guerard to work with Dr. Silvio Canonica at the Swiss Federal Institute of Aquatic Science and Technology and with Dr. J. Samuel Arey at Ecole Polytech Federale in Switzerland.
Organic contaminants in natural waters have the potential to be degraded by a variety of reaction pathways. Assessment of the fate and impact of these contaminants often hinges heavily on quantification of the principal degradation processes responsible for their removal or transformation into other compounds. It is increasingly understood that light-induced processes play a significant and complicated role in the degradation of many aquatic contaminants. This project will use state of the art computational methods to predict the single electron oxidation potentials and reaction kinetics of compounds that can undergo electron transfer upon photo excitation to the triplet excited state (sulfonamides and phenylurea herbicides) and analogues for dissolved organic matter (electron-rich phenols and substituted anilines), a heterogeneous substance ubiquitous in all natural surface waters. A novel computational approach will calculate free energy of ionization in water solutions to provide reliable computation of aqueous one-electron oxidation free energies of organic contaminants to within 1-2 kcal/mol error. The Rehm-Weller model will be applied to describe the kinetics of oxidation by triplet-excited DOM. These model developments will allow us to better assess the significance of 3DOM* for the environmental degradation of a wider range of target pollutants in aquatic systems.
