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Per- and polyfluoroalkyl substances (PFAS) are notable health concerns, leading to global drinking-water regulations for primary PFAS. However, conventional drinking-water treatment methods are ineffective in eliminating PFAS due to their resistance to such processes. Moreover, certain disinfection procedures may inadvertently generate perfluorinated compounds from polyfluorinated precursor compounds. With evolving regulations, there exists an immediate demand for both technical and non-technical solutions that water treatment facilities can adopt. Here, to address this critical gap, we examine the primary challenges tied to PFAS removal and introduce a detailed four-stage protocol. We advocate for non-technical strategies to improve PFAS removal practices. The treatment trains and management recommendations presented in this Perspective are also geared towards helping utilities comply with regulations concerning other chemical contaminants, including disinfection by-products. We emphasize the necessity for practical PFAS monitoring and treatment guidelines and encourage utilities to leverage all available resources, to positively impact public health through improved water quality. 

The oxidation of highly toxic arsenite (As(III)) was studied using humic acid-coated magnetite nanoparticles (HA-MNP) as a photosensitizer. Detailed characterization of the HA-MNP was carried out before and after the photoinduced treatment of As(III) species. Upon irradiation of HA-MNP with 350 nm light, a portion of the As(III) species was oxidized to arsenate (As(V)) and was nearly quantitatively removed from the aqueous solution. The separation of As(III) from the aqueous solution is primarily driven by the strong adsorption of As(III) onto the HA-MNP. As(III) removals of 40–90% were achieved within 60 min depending on the amount of HA-MNP. The generation of reactive oxygen species (•OH and 1O2) and the triplet excited state of HA-MNP (3HA-MNP*) was monitored and quantified during HA-MNP photolysis. The results indicate 3HA-MNP* and/or singlet oxygen (1O2) depending on the reaction conditions are responsible for converting As(III) to less toxic As(V). The formation of 3HA-MNP* was quantified using the electron transfer probe 2,4,6-trimethylphenol (TMP). The formation rate of 3HA-MNP* was 8.0 ± 0.6 × 10−9 M s−1 at the TMP concentration of 50 µM and HA-MNP concentration of 1.0 g L−1. The easy preparation, capacity for triplet excited state and singlet oxygen production, and magnetic separation suggest HA-MNP has potential to be a photosensitizer for the remediation of arsenic (As) and other pollutants susceptible to advanced oxidation. 

Short chain perfluoroalkyl substances (PFAS), replacements for long chain legacy PFAS such as perfluorooctanoic acid (PFOA), have similar toxicity, negative health effects, and exceptional persistence as long chain PFAS. β-Cyclodextrin (β-CD) is a powerful host–guest complexing agent for a number of legacy PFAS, suggesting potential β-CD-based remediation processes. We report herein that the addition of charged functional groups at the perimeter of β-CD has a pronounced influence on the strength of the β-CD:PFAS complex. The presence of a positively charged amine functionality on the perimeter of β-CD significantly increases the complexation of legacy and short chain PFAS. We assigned the enhanced complexation to electrostatic attraction between the negatively charged PFAS head group and the positively charged β-CD derivative. In comparison to neutral β-CD, addition of a negative charge to β-CD decreases complexation to PFAS due to electrostatic repulsion between the negatively charged polar head group of PFAS and the negatively charged β-CD. 19F NMR titration experiments illustrate the complexation of short chain PFAS by positive charged β-CDs over neutral β-CD, with increases up to 20 times depending on the PFAS guest. The results give further understanding to the nature of the β-CD:PFAS host–guest complex and the various intermolecular forces that drive complexation. Positively charged β-CDs appear to be potential complexing agents for remediation of short chain PFAS.