Exploring the initial bond activations of PFAS on zero-valent iron

Area of Science:

• Environmental Chemistry
• Materials Science
• Catalysis

Background:

• Per- and polyfluoroalkyl substances (PFAS) are prevalent in consumer products and linked to adverse health effects.
• Stringent regulations necessitate effective methods for PFAS degradation due to their persistent nature and strong carbon-fluorine bonds.
• Heterogeneous catalysis is a potential route for PFAS remediation, but understanding catalyst interactions is crucial.

Purpose of the Study:

• To investigate the catalytic activity of iron (Fe) surfaces for perfluorobutanoic acid (PFBA) degradation.
• To elucidate the reaction pathways and energetics of PFBA interaction with the Fe(110) surface using computational methods.
• To assess the feasibility of Fe(110) as a catalyst for cleaving PFAS C-F bonds.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to study PFBA reactions on the Fe(110) surface.
• Thermodynamics and kinetics of ten distinct reaction pathways were calculated.
• A kinetic model was developed to simulate the degradation process.

Main Results:

• Iron (Fe) was identified as a promising transition metal for cleaving C-F bonds in PFAS.
• The Fe(110) surface demonstrates the capability to degrade PFBA.
• The dominant degradation pathway involves the cleavage of the carboxylic acid head group, rather than the C-F bonds.

Conclusions:

• Fe(110) can initiate the degradation of PFBA, a representative PFAS molecule.
• While C-F bond cleavage is possible, the primary reaction mechanism focuses on the molecule's functional group.
• Further research is needed to optimize iron-based catalysts for efficient and complete PFAS remediation.