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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. 

Combined heavy metals and chlorinated organic compounds have been widely reported in industrial wastewater. Yet, simultaneous removal of these contaminants remains challenging. In this study, a bi-functional composite (TNTs@AC) was prepared based on commercial titanium dioxide (TiO2) and activated carbon (AC) and tested for simultaneous removal of Cd(II) and 2-chlorophenol (2-CP). Under the action of high temperature and pressure, TiO2 was transformed into titanate nanotubes (TNTs) and bound to AC, and in the meanwhile, nanoscale AC particles were patched on the TNTs. In the mixed TNTs and AC phases, TNTs was responsible for taking up Cd(II), whereas AC for 2-CP. As such, the relative adsorption capacities of the composite for Cd(II) and 2-CP varied with the mass ratio of TiO2:AC, with decent uptakes for both chemicals in the mass ratio rage of 1:3 ~1:1. TNTs@AC (prepared at TiO2:AC = 1:1) demonstrated fast sorption kinetics and high sorption capacities for both Cd(II) and 2-CP, with a maximum Langmuir adsorption capacity of 109 and 52 mg/g, respectively, in the single solute 

“Concentrate-and-degrade” is an effective strategy to promote mass transfer and degradation of pollutants in photocatalytic systems, yet suitable and cost-effective photocatalysts are required to practice the new concept. In this study, we doped a post-transition metal of Indium (In) on a novel composite adsorptive photocatalyst, activated carbon-supported titanate nanotubes (TNTs@AC), to effectively degrade perfluorooctanoic acid (PFOA). In/TNTs@AC exhibited both excellent PFOA adsorption (>99% in 30 min) and photodegradation (>99% in 4 h) under optimal conditions (25 °C, pH 7, 1 atm, 1 g/L catalyst, 0.1 mg/L PFOA, 254 nm). The heterojunction structure of the composite facilitated a cooperative adsorption mode of PFOA, i.e., binding of the carboxylic head group of PFOA to the metal oxide and attachment of the hydrophobic tail to AC. The resulting side-on adsorption mode facilitates the electron (e‒) transfer from the carboxylic head to the photogenerated hole (h+), which was the major oxidant verified by scavenger tests. Furthermore, the presence of In enables direct electron transfer and facilitates the subsequent stepwise defluorination. Finally, In/TNTs@AC was amenable to repeated uses in four consecutive adsorption-photodegradation runs. The findings showed that adsorptive photocatalysts can be prepared by hybridization of carbon and photoactive semiconductors and the enabled “concentrate-and-degrade” strategy is promising for the removal and degradation of trace levels of PFOA from polluted waters.