Computational Investigation of Structure–Function Relationship in Fluorine-Functionalized MOFs for PFOA Capture from Water

Abstract

A strategy that can be used to develop metal− organic frameworks (MOFs) to capture per-and poly-fluoroalkyl substances (PFAS) from water is functionalizing them with fluorine moieties. We investigated different fluorine-functionalization strategies and their performance in removing PFAS from water using molecular simulations. Perfluorooctanoic acid (PFOA), one of the most widely encountered PFAS in water sources, was used as the probe molecule. Our simulations show that fluorine functionalization by incorporating fluorinated anions as bridging ligands in MOFs creates additional binding sites for PFOA; however, the same sites also attract water molecules, which casts doubt on their potential use. In contrast, trifluoromethyl or fluorine substitution of the MOF ligands results in higher hydrophobicity. However, the pores fluorinated with this method should have the optimum size to accommodate PFOA. Likewise, post-synthetic fluorine functionalization of MOFs through grafting of perfluorinated alkanes showed increased PFOA affinity. Fluorine-functionalized MOFs with high hydrophobicity and optimized pore sizes can effectively capture PFOA from water at very low concentrations of PFOA.

Metal–Organic Framework-Based Composites for the Adsorption Removal of Per- and Polyfluoroalkyl Substances from Water

“…With the strong affinity of fluorine taken into account, the structure of MOFs was modified through fluorine functionalization. 85 Kong et al 86 synthesized fluorine-functionalized MOFs for the purpose of removing of PFOA from water. Fluorine groups offer high selectivity in terms of adsorption sites for PFOA, resulting in an adsorption capacity of 185.151 μmol/g.…”

“…With the strong affinity of fluorine taken into account, the structure of MOFs was modified through fluorine functionalization . Kong et al synthesized fluorine-functionalized MOFs for the purpose of removing of PFOA from water.…”

Review of Recent Computational Research on the Adsorption of PFASs with a Variety of Substrates

“…Erkal et al [ 71 ] reported on MOFs functionalized with fluorine atoms to capture PFASs. In this study, the authors used DFT to complete geometry optimizations of the structures.…”

Influence of Steric and Dispersion Interactions on the Thermochemistry of Crowded (Fluoro)alkyl Compounds

“…The introduction of fluorine atoms into organic molecules (usually replacing hydrogen) imparts a unique set of physicochemical properties that often enhance pharmacokinetic profiles, metabolic stability, and receptor interactions but keep many of the good properties of the parent compounds. On the other hand, per- and polyfluoroalkyl substances (PFAS) have garnered unprecedented attention in recent years, becoming a focal point of scientific inquiry, regulatory concern, and public discourse. − These synthetic compounds, characterized by their remarkable stability and hydrophobic nature, open new perspectives in industrial and commercial applications. , However, their persistent presence in the environment, coupled with potential adverse health effects, has propelled PFAS to the forefront of global environmental and health agendas. Thus, it seems clear that a detailed theoretical understanding of fluorinated organic drugs and PFAS, in particular their thermodynamic properties and kinetic stability, is of high general interest. − …”

“…10−12 These synthetic compounds, characterized by their remarkable stability and hydrophobic nature, open new perspectives in industrial and commercial applications. 13,14 However, their persistent presence in the environment, coupled with potential adverse health effects, has propelled PFAS to the forefront of global environmental and health agendas. Thus, it seems clear that a detailed theoretical understanding of fluorinated organic drugs and PFAS, in particular their thermodynamic properties and kinetic stability, is of high general interest.…”