Date of Award

3-2025

Document Type

Thesis

Degree Name

Master of Science in Engineering Management

Department

Department of Systems Engineering and Management

First Advisor

Willie F. Harper, Jr., PhD

Abstract

Per- and polyfluoroalkyl substances (PFAS), widely referred to as “forever chemicals,” exhibit high environmental persistence and potential health risks due to their robust carbon-fluorine bonds. These substances are prevalent in aqueous film-forming foams (AFFF), used in industrial and military applications, and are known to contaminate environmental surfaces, including concrete. This study aims to characterize the molecular-level interaction energies of six PFAS species—PFOA, PFOS, PFHxS, PFHxA, 6:2 FTS, and PFBS—with calcium silicate, a key component of concrete, using density functional theory (DFT) calculations. Change in Gibbs free energy (ΔG) was determined for each of the interactions, revealing negative ΔG values for all species, indicating spontaneous and favorable attachment to calcium silicate surfaces. Among the PFAS, 6:2 FTS exhibited the most negative ΔG (-0.056 Eh), suggesting it is most likely to persist on calcium silicate surfaces, while PFHxA showed the least negative ΔG (-0.033 Eh), indicating higher release potential. Correlation analyses using the ΔG results from this study and molecular mass and PFAS release rates from concrete from previous studies revealed some moderate and weak, though statistically insignificant, relationships. These findings provide insights into the retention and potential leaching behaviors of PFAS from cementitious materials, with implications for environmental contamination and remediation strategies.

AFIT Designator

AFIT-ENV-MS-25-M-079

Comments

An embargo was observed for posting this work.

Distribution Statement A: Distribution Unlimited. Approved for public release. PA case number: 88ABW-2025-0207

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