Destruction of per/poly-fluorinated alkyl substances by magnetite nanoparticle-catalyzed UV-Fenton reaction

Abstract

Novel economically-sustainable and environmentally-friendly technologies for per- and poly-fluoroalkyl substance (PFAS) destruction are becoming increasingly important as PFAS contamination has increased in drinking water throughout the globe. UV-Fenton chemistry catalyzed by nanosize magnetite (Fe₃O₄) particles in aqueous environments is a promising method for production of reactive oxygen species (ROS), capable of disrupting PFAS carbon-fluorine bonds. Here we demonstrate greater than 90% degradation efficiency for a wide variety of PFAS compounds by ROS generated in a UV-Fenton reaction, involving naturally-occurring Fe₃O₄ nanoparticles. In order to demonstrate that ROS are indeed formed under our experimental conditions, we utilized a fluorescent probe to confirm the presence of ROS in the reaction solution. PFAS destruction efficiency is increased at elevated pH levels; however, by varying both the Fe₃O₄ and hydrogen peroxide (H₂O₂) concentrations in solution, high efficiency can be achieved at neutral pH conditions, like those found in drinking water. PFAS destruction occurred with UV exposure times on the order of minutes. Nano Fe₃O₄ retained its oxidation state and catalytic efficiency after multiple cycles of PFAS destruction, indicating that the material is reusable. High resolution mass spectrometry was utilized to demonstrate destruction efficiency and to identify the degradation products. ROS generation utilizing naturally-occurring Fe₃O₄ nanoparticles has been shown to be an efficient method for PFAS destruction with potential scalability for drinking water decontamination.