Abstract
Trimethylsiloxane (TriSil) surfactants are promising alternatives to per- and polyfluoroalkyl substances (PFAS), which are global recalcitrant and persistent environmental contaminants, in aqueous film-forming fire-fighting foams (AFFF). However, much less information is available on the environmental fate and degradation of TriSil surfactants. Thus, it is important to study the degradation chemistry of fluorine-free TriSil surfactants in the solution phase under various conditions to further assess their environmental impact. This computational study reports the prominent hydrolysis, reduction, and oxidation pathways of a truncated TriSil and proposes the major degradation products using density functional theory (DFT) calculations. We have identified the polydimethylsiloxane unit of TriSil to play a prominent role in aqueous solution reactivity initiated via hydrolysis and reduction, while oxidation mainly proceeds through H-atom abstraction along the polyethylene glycol unit. The results of this study aid in establishing the use of the alternative fluorine-free surfactant, TriSil, for fire-fighting foams from an environmental perspective.
| Original language | English |
|---|---|
| Journal | Environmental Science: Advances |
| DOIs | |
| State | Accepted/In press - 2024 |
| Externally published | Yes |
Funding
The use of trade, product or firm names in this report is for descriptive purposes only and does not imply endorsement by the U.S. Government. The tests described and the resulting data presented herein were obtained from research conducted under the Installations and Operational Environments Program of the United States Army Corps of Engineers by the USAERDC under the work supported by (OUSD(R&E)) through the Applied Research for the Advancement of Science and Technology Priorities (ARAP) program. Permission was granted by the Chief of Engineers to publish this information. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. Authors also acknowledge grant of computer time from the DOD High Performance Computing Modernization Program at ERDC, Vicksburg MS. This research was supported in part by an appointment to the Department of Defense (DOD) Research Participation Program administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the U.S. Department of Energy (DOE) and the DOD. ORISE is managed by ORAU under DOE contract number DE-SC0014664. All opinions expressed in this paper are the author's and do not necessarily reflect the policies and views of DOD, DOE, or ORAU/ORISE. The work performed by MM and SV was supported by funding provided by Army Corp of Engineers (Cooperative agreement # W912HZ-20-2-0067). MM and SV also gratefully acknowledge allocated computational resources from High Performance Computing facility at Colorado School of Mines.