Document Type

Dissertation

Date of Award

12-31-2025

Degree Name

Doctor of Philosophy in Materials Science and Engineering - (Ph.D.)

Department

Chemical and Materials Engineering

First Advisor

S. Basuray

Second Advisor

Joshua Young

Third Advisor

Wen Zhang

Fourth Advisor

Gennady Gor

Fifth Advisor

Mengyan Li

Abstract

Per- and polyfluoroalkyl substances (PFAS) are a large family of chemicals that have seen wide usage due to their fluorinated carbon backbone. The presence of strong C-F bonds in the backbone lends PFAS molecules high thermal and chemical stability, as well as strong hydrophobicity and lipophobicity. This combination of properties has led to heavy use of PFAS as surfactants, non-stick coatings, and aqueous foam forming films and flame retardants. However, these properties bring their own consequences. The high chemical and thermal stability of PFAS renders them persistent, with the C-F bonds resisting naturally occurring forms of degradation. Existing forms of water treatment, such as activated carbon and ion exchange resins, each have their own deficiencies for removing PFAS. The discovery of emerging health risks associated with PFAS has led to a surging interest in novel materials for the removal of PFAS from the environment.

This dissertation focuses two classes of nanoporous materials. The first class is metal-organic frameworks (MOFs), a family of highly porous coordination polymers consisting of metallic clusters coordinated by organic linkers to form a network. The second class is covalent organic frameworks (COFs), which are porous polymers consisting of low molecular-weight elements (e.g., C, H, N, B, 0). Both MOFs and COFs can form porous networks with high internal surface areas and pore volumes, which have made them strong candidates for adsorptive remediation. While both MOFs and COFs have been studied for adsorption, the large number of potential MOF/COF structures, as well as the large variety of aqueous contaminants to be studied, has resulted in limited experimental research specifically aimed at the removal of PFAS from aqueous environments using MOFs/COFs. However, computational methods, such as density functional theory (DFT) and Monte Carlo (MC) simulations, provide a means for investigating the adsorption of PFAS in these structures, as well as the design principles that influence PFAS adsorption.

Chapter 1 explores the problems of emerging organic contaminants being faced in the 21st century. Chapter 2 discusses the threat PFAS pose on the environment, the current state of the art of PFAS remediation, and how nanoporous crystalline materials such as MOFs and COFs fit into this field. Chapter 3 describes the different computational methods utilized in this work, with a focus on DFT, ab initio molecular dynamics (AIMD), and MC simulations. Chapter 4 investigates the PFAS adsorption capability of a family of MOFs, M-MOF-74, and the role that the metal oxide cluster and the protonation state of PFAS plays on the adsorption strength. Chapter 5 illustrates the effects of functionalization on the adsorption of PFAS in COF-300, a nitrogen-based COF structure. Chapter 6 examines the design principles at play in the adsorption of PFOA in a large number of COF structures, and how COF design influences the effects of functionalization. Chapter 7 concludes with a review of what has been learned, and recommendations for future work that may further improve the understanding of PFAS adsorption in nanoporous materials, and how novel MOFs and COFs can be designed to improve their PFAS remediation capabilities.

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