Mechanistic Insights into Per- and Polyfluoroalkyl Substance (PFAS) Photolysis under Intensified Simulated Solar...

Area of Science:

• Environmental Chemistry
• Photochemistry
• Water Remediation

Background:

• Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants.
• PFAS pose significant risks to ecosystems and human health.
• Natural photolysis is considered ineffective for PFAS degradation.

Purpose of the Study:

• To investigate the unexpected decomposition of PFAS under simulated solar light.
• To elucidate the mechanism of PFAS photolysis in a catalyst-free environment.
• To explore sustainable remediation strategies for PFAS contamination.

Main Methods:

• Simulated solar light irradiation of PFCAs and GenX.
• Detection of degradation products using mass spectrometry.
• Identification of reactive species using electron spin resonance and transient absorption spectroscopy.
• Theoretical elaboration of reaction pathways.

Main Results:

• GenX showed up to 49.1% degradation and 21.2% defluorination within 5 hours.
• Hydrogen radicals, produced from water photoexcitation, were identified as key reactive species.
• Decarboxylated and hydrodefluorinated intermediates were detected.
• UV wavelengths below 300 nm were found crucial for hydrogen radical-driven defluorination.

Conclusions:

• PFAS, particularly PFCAs and GenX, can be decomposed by simulated solar light.
• Hydrogen radicals play a significant role in PFAS defluorination, challenging previous models.
• UV light below 300 nm is more effective for PFAS defluorination than longer wavelengths.
• This research offers a novel approach for sustainable PFAS remediation using light-based technologies.