Candidate: Melissa Marciesky

Title: Advancing Fundamental Computational Approaches to Enable PFAS Degradation

Abstract: Per- and polyfluoroalkyl substances (PFAS) are an increasingly concerning environmental hazard. Both bioremediation and chemical destruction (e.g. via reduction or oxidation, “redox”) routes are currently being investigated for PFAS mitigation. Bioremediation has the potential to fill a critical need for a cost-effective and adaptable remediation route, as it has been used for complete degradation of other pollutants, even in complex environmental media like soils, while causing little environmental disturbance. However, only a few studies have focused on enzymatic degradation, and the link has yet to be made between the bacteria capable of biodegradation and the exact enzymes involved. Only one well studied enzyme, fluoroacetate dehalogenase (FAcD), is naturally evolved to break the strong C-F bond, but it is ineffective on PFAS. On the other hand, there have been many chemical redox systems investigated for PFAS. Many rely on metal-ion-based homogenous or heterogenous catalysts to generate highly oxidative or reductive species. There is some evidence of PFAS metal-ion complexes aiding in redox degradation of these compounds, but the impacts of PFAS adsorption or complexation on degradation pathways and rates is still not well understood. This work explores in silico methods as a strategy to improve both bioremediation and redox degradation routes. The overall goal of this research is to advance computational approaches to simulating PFAS properties and behavior while enhancing degradation. This goal is addressed via three complementary aims focused on advancing basic computational methods, understanding the effects of PFAS metal-ion complexes on degradation routes, and redesigning enzymes for PFAS defluorination.

Chair:

Dr. Carla (Baumel) Ng

Chemical and Petroleum Engineering; Civil and Environmental Engineering, University of Pittsburgh

Committee Members:

Dr. John A. Keith

Chemical and Petroleum Engineering, University of Pittsburgh

Dr. Prashant N. Kumta

Bioengineering; Chemical and Petroleum Engineering, University of Pittsburgh

Dr. Jason E. Shoemaker

Chemical and Petroleum Engineering, University of Pittsburgh

Dr. Scott M. Simpson

Chemistry, St. Bonaventure University