This SERDP and ESTCP webinar focuses on DoD-funded research efforts to remediate sites impacted by per- and polyfluoroalkyl substances (PFAS) and to identify alternatives to AFFF (aqueous film forming foam). Specifically, investigators will cover strategies to enhance PFAS mineralization during thermal reactivation of granular activated carbon (GAC) and developments in replacing AFFF with polyethylene oxide-based polymers.
“Thermal Reactivation of Spent Granular Activated Carbon Containing Per- and Polyfluoroalkyl Substances” by Dr. Detlef Knappe ( SERDP Project ER20-3044)
This project supports SERDP’s efforts to reduce Department of Defense (DoD) liabilities by improving technologies for the remediation of PFAS-contaminated water to protect human health and the environment. The most widely applied approach for remediating PFAS-contaminated water is granular activated carbon (GAC) adsorption. After treating water, the GAC contains concentrated PFAS, which also needs to be managed. One management option is to thermally reactivate spent GAC and reuse the reactivated product. The objective of this research is to identify conditions that both effectively mineralize PFAS during thermal reactivation of GAC and allow safe reuse of reactivated GAC. Thermogravimetric analysis (TGA) experiments with pure PFAS in acid and salt forms as well as with PFAS/base and PFAS/salt mixtures were conducted to determine the thermal stability of nine PFAS forms. TGA experiments were conducted both in the absence of GAC as well as with GAC containing known PFAS loadings. Off-gases from TGA experiments were collected with impingers to trap products soluble in basic water and Summa canisters to capture volatile and semi-volatile PFAS that pass through the impingers. The method was developed to establish a fluorine mass balance. This presentation will describe the thermal behavior of PFAS as well as strategies to enhance PFAS mineralization during thermal reactivation of GAC.
“Polyethylene Oxide-based Polymer Formulations for PFAS Free Fire Suppression” by Dr. Braden Giordano ( SERDP Project WP20-1530)
The time for replacing AFFF with fluorine-free alternatives is fast approaching. A strategy was developed to a design drop-in replacement based upon the chemical modification of polyethylene oxide (PEO). PEO is compatible with existing AFFF formulations, improves hose stream pressure, reach, and volume, and is low toxicity, as demonstrated by its frequent use in cosmetics manufacturing. These properties make PEO an ideal candidate for replacing PFAS in firefighting foams. However, PEO does not have the affinity for both oil and water that is necessary to form the stable foams that prevent vapors from fuel pools from feeding fires. This objective of this project is to create polymers with PEO backbones that have dual affinity for oil and water using reversible addition-fragmentation chain transfer (RAFT)-mediated synthesis. We describe the synthesis pathway and analytical verification of synthesized polymers, present laboratory-scale testing results for foam degradation and fuel transport rates, and detail future validation through bench-scale and large-scale testing. Results indicate that the concept of a PEO-based drop-in replacement is promising.
Dr. Detlef Knappe is the S. James Ellen Distinguished Professor of Civil, Construction, and Environmental Engineering at North Carolina State University (NC State). He is also the deputy director of NC State’s Center for Environmental and Health Effects of PFAS. Dr. Knappe’s research interests broadly encompass drinking water quality and treatment. He is a Trustee of the American Water Works Association’s (AWWA) Water Science and Research Division and an associate editor for AWWA Water Science. He is also a member of the NC Secretaries’ Science Advisory Board. Dr. Knappe received his bachelor’s, master’s, and doctoral degrees in civil and environmental engineering at the University of Illinois at Urbana-Champaign.
Dr. Braden Giordano is a research chemist at the U.S. Naval Research Laboratory in Washington, DC. He serves as the head of the Chemical Sensing and Fuel Technology Section in the Navy Technology Center for Safety and Survivability. He has served as a principal and co-investigator for projects funded by SERDP, the Office of Naval Research, the Defense Threat Reduction Agency, and the Department of Homeland Security. Dr. Giordano has authored over 40 peer-reviewed papers and book chapters and delivered over 100 technical presentations and posters. His interest in developing replacements for AFFF comes from his experience developing micelle-based separation media for electrophoresis applications. Dr. Giordano received a bachelor’s degree in chemistry from the University of Richmond and a doctoral degree in chemistry from the University of Virginia.