MEETS (Materials, Energy, EnvironmenT Seminars)

It has been known for several decades that routine analytical methods are unable to identify a substantial fraction of the total fluorine in environmental samples. As much as 97% of the total fluorine in some samples remains unknown. This unknown mass balance of fluorine continues to grow as new definitions for per- and polyfluoroalkyl substances (PFAS) raise the number of unique compounds upwards of 7 million, while the most comprehensive targeted mass spectrometry methods quantify only 100’s of PFAS.

¹⁹F NMR offers unique insight into environmental fluorine contamination. NMR is a non-selective detector with the ability to solve structures without the use of libraries. If environmental research is restricted to libraries of previously identified molecules, then we spend our time looking for what is known, potentially missing transformation products or new classes of pollutants. ¹⁹F NMR has analytical advantages of minimal background, no required anticipation of types of functional groups present, and minimal impact from the sample matrix. However, sensitivity is a longstanding concern when using NMR in an environmental context.

In this research, I use novel NMR experiments and data analysis tools to improve the sensitivity of NMR, allowing for trace analysis in a variety of samples. For the first time, the true extent of organic fluorine contamination is revealed in drinking water, wastewater, biosolids, polar bears, and humans. Across all samples, there is a significant portion of aromatic fluorine chemistry arising from agricultural and pharmaceutical compounds. These trifluoromethyl groups account for much of the unknown fluorine mass balance and raises important questions regarding the persistence and long-range transport potential of these molecules. ¹⁹F NMR also identifies a plethora of legacy and next generation PFAS in every sample. The results from this research are used to better inform mass spectrometry methods, resulting in a more complete understanding of environmental PFAS contamination.

Catalysts can be good at multitasking when possessing the right tools (sites). This talk will present two catalytic strategies aiming to close the carbon cycle: CO₂ capture and utilization (CCU) and biomass valorization. First, we will address the synthesis of inverse metal oxide–metal catalysts for the hydrogenation of CO₂ to methanol and the addition of a sorbent component for the development of dual-function materials (CO₂ capture and conversion). This one-pot approach has the potential to eliminate current energy-intensive and corrosive CO₂ capture and storage processes while producing important commodity chemicals and fuels. Secondly, we will discuss the ability of polystyrene sulfonic acid-based catalysts to combine the advantages of homogeneous and heterogeneous catalysis. In this regard, we will present our efforts in the development of novel soluble and reusable polymer catalysts with Brønsted and Lewis acid sites for the one-pot synthesis of hydroxymethylfurfural (HMF) from glucose and potato starch. HMF is a valuable platform chemical, and there is an important market for some of its derivatives, such as furandicarboxylic acid (FDCA) and adipic acid.