Polyfluoroalkyl Substances In Water Research Articles

Insights into Photo/Electrocatalysts for the Degradation of Per- and Polyfluoroalkyl Substances (PFAS) by Advanced Oxidation Processes

Per- and polyfluoroalkyl substances (PFASs) are an emerging group of persistent organic pollutants in aquatic environments with high levels of toxicity and bioaccumulation. The risks posed by PFASs to the environment and health have attracted increasing attention. To remove them from water, advanced oxidation processes (AOPs), with the merits of high efficiency and low cost, are mainly used. Photo/electrocatalytic heterogeneous AOPs, with the assistance of nanostructured catalysts and external energy in the form of light/electricity, have emerged as one of the most powerful techniques, overcoming the difficulty associated with defluorination and achieving the effective and complete degradation of PFASs in water. The structures of photo/electrocatalysts play a critical role in the production of reactive oxygen species, the electron transfer process, and the degradation pathway and its efficiency. Herein, to elucidate the structure–performance relationship, a review of photo/electrocatalysts for the enhanced degradation of PFASs in heterogeneous AOPs, organized according to their composition and nanostructure design, is provided. This review article is mainly focused on (1) the mechanisms and pathways of PFAS degradation by heterogeneous photo/electrocatalytic AOPs, and (2) the structural designs and modifications of photo/electrocatalysts for the enhanced degradation of PFASs by heterogeneous AOPs. Finally, the challenges and prospects for future research into photo/electrocatalysts of heterogeneous AOPs in the field of PFAS remediation are discussed.

Molecular interactions in short-chain perfluoroalkyl carboxylic acids and aqueous solutions.

The presence of short-chain per- and polyfluoroalkyl substances in water poses a major health and environmental challenge. Here, we have performed high-energy small- and wide-angle X-ray scattering measurements on CF3[CF2]nCOOH (where n = 1, 2, 3 represents the chain length) and their aqueous solutions at 10% mole concentrations to characterize their molecular interactions at the atomic and nanometer length scales. The experimental wide-angle structure factors have been modelled using Empirical Potential Structural Refinement. The oxygen-oxygen partial X-ray pair distribution functions show that the coordination number between the hydroxyl oxygen on the acid and surrounding oxygen water molecules increases significantly with acid chain length, rising from 3.2 for n = 1 to 4.1 for n = 3. The small-angle scattering is dominated by a sharp, high-intensity peak at Q1 ∼ 0.2 Å-1 and a smaller peak at Q2 = 1.2 Å-1 for n = 3, both of which decrease with decreasing chain length. The Q2 peak is attributed to groups of adjacent non-bonded acid molecules, and Q1 has contributions from both correlations between acid molecules and water-water interactions. In all cases, the models show nanoscale aggregation occurs in the form of denser channels of winding hydrogen-bonded chains, approximately 20 water molecules in length, surrounding clusters of acid molecules. This article is part of the theme issue 'Exploring the length scales, timescales and chemistry of challenging materials (Part 2)'.

A ReaxFF-based molecular dynamics study of the destruction of PFAS due to ultrasound

This work uses a computational approach to provide a mechanistic explanation for the experimentally observed destruction of per- and polyfluoroalkyl substances (PFAS) in water due to ultrasound. The PFAS compounds have caused a strong public and regulatory response due to their ubiquitous presence in the environment and toxicity to humans. In this research, ReaxFF -based Molecular Dynamics simulation under several temperatures ranging from 373 K to 5,000 K and different environments such as water vapor, O2, N2, and air were performed to understand the mechanism of PFAS destruction. The simulation results showed greater than 98% PFAS degradation was observed within 8 ns under a temperature of 5,000 K in a water vapor phase, replicating the observed micro/nano bubbles implosion and PFAS destruction during the application of ultrasound. Additionally, the manuscript discusses the reaction pathways and how PFAS degradation evolves providing a mechanistic basis for the destruction of PFAS in water due to ultrasound. The simulation showed that small chain molecules C1 and C2 fluoro-radical products are the most dominant species over the simulated period and are the impediment to an efficient degradation of PFAS. Furthermore, this research confirms the empirical findings observations that the mineralization of PFAS molecules occurs without the generation of byproducts. These findings highlight the potential of virtual experiments in complementing laboratory experiments and theoretical projections to enhance the understanding of PFAS mineralization during the application of ultrasound.

Brackish and Saline Groundwater Use—Is It Time to Reconsider USDW?

Groundwater Monitoring & RemediationAccepted Articles Regulator Perspective Brackish and Saline Groundwater Use – Is it time to reconsider USDW? Charles Job, Charles Job NGWA Regulatory Affairs Manager cjob@ngwa.org Search for more papers by this author Charles Job, Charles Job NGWA Regulatory Affairs Manager cjob@ngwa.org Search for more papers by this author First published: 11 April 2023 https://doi.org/10.1111/gwmr.12581 This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/gwmr.12581. AboutRelatedInformationPDFPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessClose modalShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Accepted ArticlesAccepted, unedited articles published online and citable. The final edited and typeset version of record will appear in the future. RelatedInformation RecommendedA Geochemical Approach to Determine Sources and Movement of Saline Groundwater in a Coastal Aquiferby Robert Anders, Gregory O. Mendez, Kiyoto Futa, Wesley R. Danskin, GroundwaterAn Analytical Method for Assessing Recharge Using Groundwater Travel Time in Dupuit‐Forchheimer Aquifersby R. Chesnaux, S. Santoni, E. Garel, F. Huneau, GroundwaterField Verification of Stable Perched Groundwater in Layered Bedrock UplandsJonathon T.V. Carter, Madeline B. Gotkowitz, Mary P. Anderson, GroundwaterField Evaluation of the Sentinel™ Integrative Passive Sampler for the Measurement of Perfluoroalkyl and Polyfluoroalkyl Substances in Water Using a Modified Organosilica AdsorbentPaul L. Edmiston, Erika Carter, Kevin Toth, Riley Hershberger, Noah Hill, Patrick Versluis, Patrick Hollinden, Craig Divine, Groundwater Monitoring & Remediation

Photocatalytic Degradation of Perfluorooctanoic Acid on Pb-doped TiO2 Coated with Reduced Graphene Oxide.

Poor reactivity of extraordinarily strong per- and polyfluoroalkyl substances (PFAS) with TiO2 makes it necessary to advance photocatalytic materials. In this present work, lead (Pb)-doped TiO2 coated with reduced graphene oxide (TiO2 -Pb/rGO) was prepared using hydrothermal method and then its photocatalytic activity with various PFAS in water, especially perfluorooctanoic acid (PFOA), was investigated. PFAS decomposition kinetics by TiO2 -Pb/rGO was compared to neat TiO2 , Pb-doped TiO2 (TiO2 -Pb) and rGO-coated TiO2 (TiO2 /rGO). TiO2 -Pb/rGO (0.33 g/L) under UV showed superior removal of PFOA (10 mg/L) at 98% after 24 hr, following TiO2 -Pb/UV at 80%, TiO2 /rGO/UV at 70%, TiO2 /UV at <10%, and UV at <10%. Doping of TiO2 with Pb and introduction of rGO to TiO2 greatly changed the physicochemical properties of TiO2 and the subsequent charge transfer mechanism. Radical scavenger experiments indicated that holes, superoxide radical anion, and singlet oxygen were responsible for the observed PFOA decomposition. Decomposition of PFOA by TiO2 -Pb/rGO under UV led to formation of short-chain perfluorocarboxylic acids (PFCAs) as reaction intermediates through step-by-step removal of CF2 units. Polyfluoroalkyl substance (6:2 fluorotelomer sulfonate (6:2FTS)) and long-chain PFCAs such as PFOA were significantly removed and defluorinated by TiO2 -Pb/rGO while it was ineffective towards perfluorosulfonic acids and short-chain PFCAs. Removal kinetics decreased in order of 6:2FTS > PFOA >> PFOS > PFHpA ≈ PFHxS ≈ PFBA ≈ PFBS. Pb doping to TiO2 /rGO showed better performance than Fe doping. Overall, this study implied that proper designing of TiO2 photocatalytic materials enables to expedite decomposition of persistent organic pollutants in water, in particular highly challenging fluorinated chemicals.

Field Evaluation of the Sentinel™ Integrative Passive Sampler for the Measurement of Perfluoroalkyl and Polyfluoroalkyl Substances in Water Using a Modified Organosilica Adsorbent

AbstractA passive sampler specifically designed to measure perfluoroalkyl and polyfluoroalkyl substances (PFAS) in water was tested in four study areas (Ellsworth and Peterson Air Force bases, CO and SD; the Ohio River, OH, WV, KY, IN; and the Santa Ana River, CA). Locations included both groundwater and surface water locations. Over the 2‐year study, 96 passive samplers were deployed at 33 sample locations and were compared with co‐collected grab samples, all of which were measured for 19 PFAS analytes by HPLC–MS/MS. Correlations were observed (typically within 2× difference) between aqueous PFAS concentrations measured by passive versus discrete grab samples across over 5 orders of magnitude in concentration (0.5 to 150,000 ng/L). Overall relative percent difference between grab and passive results displayed a median of 18% (interquartile range of −19 to 73%). Detection limits were around 1 ng/L for a 2‐week sampling time with sampling rates ranging from 12 to 70 mL/day in flowing systems. Duplicate samplers were deployed in all study areas which indicated a 14 to 42% (median 24%) relative standard deviation in the precision of passive sampling. Larger variances were seen with sites with higher and potentially more variable water flows. A sub‐set of duplicate samplers were measured by a commercial laboratory which returned equivalent data to research laboratory measurements (43 [±26 SD]% relative percent difference). Standardized protocols and calculation methods were developed to facilitate expanded testing and future broader use of passive sampling for PFAS by site investigators.

Calibration of Perfluorinated Alkyl Acid Uptake Rates by a Tube Passive Sampler in Water.

Per- and polyfluoroalkyl substances (PFAS) are a group of 4000+ man-made compounds of great concern due to their environmental ubiquity and adverse effects. Despite a general interest, few reliable detection tools for integrative passive sampling of PFAS in water are available. A microporous polyethylene tube with a hydrophilic-lipophilic balance sorbent could serve as a flow-resistant passive sampler for PFAS. The tube's sampling rate, Rs, was predicted based on either partitioning and diffusion, or solely diffusion. At 15 °C, the laboratory measured Rs for perfluorohexanoic acid of 100+/-81 mL day-1 were better predicted by a partitioning and diffusion model (48+/-1.8 mL day-1) across 10-60 cm s-1 water flow speeds (15+/-4.2 mL day-1 diffusion only). For perfluorohexane sulfonate, Rs at 15°C were similarly different (110+/-60 mL day-1 measured, 120+/- 63 versus 12+/-3.4 mL day-1 in respective models). Rs values from field deployments were in-between these estimates (46 +/-40 mL day-1 for perfluorohexanoic acid). PFAS uptake was not different for previously biofouled membranes in the laboratory, suggesting the general applicability of the sampler in environmental conditions. This research demonstrates that the polyethylene tube's sampling rates are sensitive to the parameterization of the models used here and partitioning-derived values should be used.

Laboratory validation of an integrative passive sampler for per- and polyfluoroalkyl substances in water

The integrative response of a PFAS-specific passive sampler was evaluated in water streams where the concentration varied with time. An integrative response regime over 90 days was observed for most PFAS analytes.

Plasma-based Decomposition of Per- and Polyfluoroalkyl Substances in Water: Plasma Source Exploration, Batch Kinetics, Effects of Water Conductivity, and an Architecture for Continuous Flow Processing

Plasma-based Decomposition of Per- and Polyfluoroalkyl Substances in Water: Plasma Source Exploration, Batch Kinetics, Effects of Water Conductivity, and an Architecture for Continuous Flow Processing

Spatiotemporal patterns of PFAS in water and crop tissue at a beneficial wastewater reuse site in central Pennsylvania.

Per- and polyfluoroalkyl substances (PFAS) are a collective name for thousands of synthetic compounds produced to enhance consumer and industrial products since the 1940s. They do not easily degrade, and some are known to pose serious ecological and human health concerns at trace concentrations (ng L-1 levels). Per- and polyfluoroalkyl substances persist in treated wastewater and are inadvertently introduced into the environment when treated wastewater is reused as an irrigation source. The Pennsylvania State University (PSU) has been spray-irrigating its wastewater at a 2.45 km2 mixed-use agricultural and forested site known as the "Living Filter" since the 1960s. To understand the spatiotemporal patterns of 20 PFAS at the Living Filter, water samples were collected bimonthly from fall 2019 through winter 2021 from the PSU's wastewater effluent and from each of the site's 13 monitoring wells. Crop tissue was collected at the time of harvest to assess PFAS presence in corn silage and tall fescue grown at the study site. Total measured PFAS concentrations in the monitoring wells ranged from nondectable to 155ng L-1 , with concentrations increasing with the direction of groundwater flow. Concentrations within each well exhibited little temporal variability across sampling events, with mixed relationships between PFAS and groundwater elevation observed between wells. Further, >84% of the PFAS present in livestock feed crops were short-chain compounds, with PFAS consumed annually by livestock fed crops harvested from the site estimated to be 2.46-7.67mg animal-1 yr-1 . This research provides insight into the potential impacts of long-term beneficial reuse of treated wastewater on groundwater and crop tissue quality.

Spatial distribution, compositional profile, sources, ecological and human health risks of legacy and emerging per- and polyfluoroalkyl substances (PFASs) in freshwater reservoirs of Punjab, Pakistan

Per- and polyfluoroalkyl substances (PFASs) are a large group of chemicals reported in global environment and are responsible for various adverse impacts on humans and environment. We report a comprehensive study on occurrence of PFASs, including legacy, substitute and emerging ones, from Pakistan. Surface water samples were collected from five ecologically important freshwater reservoirs in Pakistan, namely, Head Panjnad (HP), Head Trimmu (HT), Chashma Barrage (CB), Head Blloki (HB), and Head Qadirabad (HQ). The detection frequencies of PFASs ranged between 37 %–100 %. The highest concentration of ∑15PFASs was detected at HP (114.1 ng L−1), whereas the lowest at HQ (19.9 ng L−1). Among the analyzed PFASs, 6:2 fluorotelomer sulfonic acid (6:2 FTS) and perfluorooctanoic acid (PFOA) showed maximum mean concentrations of 9.1 ng L−1 and 7 ng L−1 at HP, followed by Perfluorooctane sulfonic acid (PFOS) with level of 0.99 ng L−1 at HT. The ecological risk assessment for selected species i.e., daphnid, mysid, fish and green algae showed that PFOS, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) exhibited moderate risk i.e., Hazard Quotients (HQs) < 1 to the modeled organisms, whereas perfluorobutane sulfonic acid (PFBS) showed the high risk to green algae (HQs = 8.6) and PFOA presented a high risk to all the organisms (HQs ranged between 1.04 and 7.38). The level of ∑PFASs at HP (114.1 ng L−1) exceed the EU guideline value of ∑PFASs in water (100 ng L−1), however the risk quotient (RQmix) values of all age groups were < 1 implying that the detected PFASs in water do not pose risk to human health. Source apportionment through Positive Matrix Factorization (PMF) showed that industrial effluent is the main source of PFASs in freshwater reservoirs. Comparable concentrations of legacy and substitute PFASs in this study indicate that legacy PFASs are still in use adjacent to ecologically important water reservoirs.

Metal-doped carbon-supported/modified titanate nanotubes for perfluorooctane sulfonate degradation in water: Effects of preparation conditions, mechanisms, and parameter optimization

Metal-doped, activated carbon (AC) supported titanate nanotubes (Me/TNTs@AC) have been shown promising for photocatalytic degradation of per- and polyfluoroalkyl substances (PFAS). However, the preparation recipe of the adsorptive photocatalysts has not yet been optimized in terms of type and content of precursor ACs and the metal dopants as well as synthesizing conditions. In this work, the photocatalytic performance of Me/TNTs@AC was evaluated based on the effectiveness in defluorination of pre-sorbed perfluorooctane sulfonic acid (PFOS) after 4-h UV irradiation. Based on the experimental results, the highest photocatalytic mineralization efficiency (66.2 %) of PFOS was achieved using Ga/TNTs@AC prepared under the following conditions: Filtrosorb-400® = 50 wt%, Ga = 2 wt%, hydrothermal treatment temperature = 130 °C, hydrothermal duration = 72 h, and calcination temperature = 550 °C. To understand the underlying mechanisms, selected materials were characterized via X-ray diffraction, the BET surface area and pore volume, UV–vis diffuse reflectance spectrometry, and photoluminescence. The results revealed that the superior photoactivity of Ga/TNTs@AC is attributed to the Ga-facilitated formation of pure crystallized anatase phase during the calcination, high UV light absorption, formation of microscale hybrid AC-anatase-Ga phases, and oxygen defects induced by Ga3+. The information can facilitate preparation and optimization of composite photocatalysts for efficient adsorption and photocatalytic degradation of PFAS in water.

Removal of PFASs from water by carbon-based composite photocatalysis with adsorption and catalytic properties: A review.

Per- and polyfluoroalkyl substances (PFASs) are a class of persistent organic pollutants widely distributed in aquatic environments. The adsorption and photocatalytic methods have been widely used to remove PFASs in water because of their respective advantages. Still, they have apparent defects when used alone. Therefore, the adsorption and photocatalytic technologies are combined through suitable preparation methods, and the excellent properties of the two are used to synergize the treatment of organic pollutants. This strategy of "concentrating" pollutants and then degrading them in a centralized manner plays an essential role in removing trace PFASs. Nevertheless, a review focusing on this kind of adsorption photocatalyst system is lacking. This review will fill this gap and provide a reference for developing a carbon-based composite photocatalyst. Firstly, different carbon-based composite photocatalysts are reviewed in detail, focusing on the differences in various composite materials' excellent adsorption and catalytic properties. Secondly, the factors influencing the removal effect of carbon-based composite photocatalysts are discussed. Thirdly, the removal mechanism of carbon-based composite photocatalysts is summarized in detail. The removal process involves two steps: adsorption and photodegradation. The adsorption process involves multiple cooperative adsorption mechanisms, and photocatalytic degradation includes oxidative and reductive degradation. Fourthly, the comparison of adsorption-photocatalysis with common treatment techniques (including removal rate, range of adaptation, cost, and the possibility of expanding application) is summarized. Finally, the prospects of carbon-based composite photocatalysts for repairing PFASs are given by evaluating the performance of different composites.

Effectiveness of Non-Thermal Plasma Induced Degradation of Per- and Polyfluoroalkyl Substances from Water

Per- and polyfluoroalkyl substances (PFAS) are omnipresent synthetic chemicals. Due to their industrial importance and widespread use as a key component in various applications and a variety of products, these compounds can be found today in high concentrations (&gt;1 μg/L) in surface and groundwater but also spread throughout the ecosystem, where they represent a serious threat to most living organisms. The removal or degradation of PFAS contaminants from water and soil is becoming a legal obligation in a growing number of countries around the globe. This, however, demands novel techniques for the degradation of PFAS since conventional water treatment techniques are either insufficient or extremely expensive due to the persistent nature of these compounds caused by their extraordinary chemical stability. The goal of this work was therefore to investigate the practical potential of the application-oriented use of atmospheric non-thermal plasma as a powerful advanced oxidation method for the purification of water contaminated with PFAS compounds. Special attention was devoted to the development of the concept that can be scaled up to the capacity level of approximately 100–200 m3 of water per hour, contaminated with PFAS and other contaminants including organic and inorganic material generally present in soil, and surface or groundwater. Our major research interest was to define the minimum required treatment time for optimal purification results, as well as to understand the influence of the initial concentration of PFAS in water and the potential presence of co-contaminants often present in situ on the efficiency of the degradation process. A chemical analysis of the treated samples demonstrated the ability of the atmospheric plasma to reduce more than 50% of the initial PFAS amount in the water samples in less than 300 s of treatment time. PFOA, however, showed more rigidity towards degradation, where a double treatment time was needed to reach similar degradation levels. The obtained results showed that the initial concentration level does not play a major role in the process. However, the PFAS degradation profiles for all tested concentrations show a strongly nonlinear behavior with time, characterized by the fast decrease of the process efficiency in the case of longer treatment times. For prolonged treatment times, a constant increase in the samples’ conductivity was measured, which might be the limiting factor for the degradation rate in the case of prolonged treatment times.

Review on Per- and Poly-Fluoroalkyl Substances’ (PFASs’) Pollution Characteristics and Possible Sources in Surface Water and Precipitation of China

In recent years, due to the production and use of per- and poly-fluoroalkyl substances (PFASs), the research on the pollution characteristics and sources of PFASs in surface water and precipitation in China has attracted increasing attention. In this study, the related published articles with sampling years from 2010 to 2020 were reviewed, and the concentration levels, composition characteristics and possible sources of PFASs in surface water (rivers and lakes) and precipitation in China were summarized, including those in the Tibetan Plateau region. The results show that the concentrations of PFASs in surface water in different areas of China vary greatly, ranging from 0.775 to 1.06 × 106 ng/L. The production processes of fluorinated manufacturing facilities (FMFs) and sewage discharge from wastewater treatment plants (WWTPS) were the main sources of PFASs in surface water in China, and the concentrations of PFASs in water flowing through cities with high urbanization increased significantly compared with those before water flowed through cities with high urbanization. The compositions of PFASs in surface water gradually changed from long-chain PFASs, such as per-fluoro-octanoic acid (PFOA) and per-fluoro-octanesulfonic acid (PFOS) to short-chain PFASs, such as per-fluorobutanoic acid (PFBA), per-fluorobutanesulfonic acid (PFBS), perfluorohexanoic acid (PFHxA) and per-fluoropentanoic acid (PFPeA). The concentrations of PFASs in precipitation in China ranged from 4.2 to 191 ng/L, which were lower than those of surface water. The precipitation concentrations were relatively high around a fluorination factory and in areas with high urbanization levels. PFASs were detected in the surface water and precipitation in the Tibetan Plateau (TP), which is the global “roof of the world”, but the concentrations were low (0.115–6.34 ng/L and 0.115–1.24 ng/L, respectively). Local human activities and surface runoff were the main sources of PFASs in the surface water of the Tibetan Plateau. In addition, under the influence of the Southeast Asian monsoon in summers, marine aerosols from the Indian Ocean and air pollutants from human activities in Southeast Asia and South Asia will also enter the water bodies through dry and wet depositions. With the melting of glaciers caused by global warming, the concentration of PFASs in the surface water of the TP was higher than that before the melting of glaciers flowed into the surface water of the TP. Generally, this study summarized the existing research progress of PFAS studies on surface water and precipitation in China and identified the research gaps, which deepened the researchers’ understanding of this field and provided scientific support for related research in the future. The concentrations of PFASs in the water bodies after flowing through FMFs were significantly higher than those before water flowed through FMFs, so the discharge of the FMF production process was one of the main sources of PFASs in surface water.

Mitigation of PFAS in U.S. Public Water Systems: Future steps for ensuring safer drinking water

AbstractThe circulation and usage of per‐ and polyfluoroalkyl substances (PFAS) and PFAS‐derived products, such as Teflon and aqueous film‐forming foam (AFFF), have led to PFAS being found in organisms worldwide. PFAS are emerging chemical contaminants that are toxic and take a long time to break down in the environment. PFAS can cause adverse health effects, including kidney cancer, testicular cancer, and ulcerative colitis. Studies have shown a widespread presence of PFAS in public water systems and people across the United States. The main pollution sources that contribute to PFAS in water are the chemical manufacturing industry, AFFF runoff, and landfills. With the health issues associated, and the occurrence in water systems, action should be taken to reduce PFAS in drinking water. Despite the adverse health effects associated with PFAS, the Environmental Protection Agency has not yet set enforceable limits for the chemicals in drinking water. Future actions should tackle two areas: (1) reducing the contamination at the pollution source and (2) improving the quality of PFAS contaminated drinking water. Five recommendations are suggested for key stakeholders. Contamination can be reduced by setting stricter industrial controls for waste streams, phasing out AFFF usage, and banning the majority of PFAS. Drinking water quality can be improved through setting state‐enforced maximum contaminant levels and equipping water treatment plants with adequate PFAS removal technologies. Application of these recommendations could help reduce the presence of PFAS in drinking water and ensure safer drinking water for communities across the United States.

Occurrence of per- and polyfluoroalkyl substances in water: a review

The environmental occurrence of PFAS in different water systems and their likely sources and fate is discussed.

Removal of perfluoroalkyl and polyfluoroalkyl substances in water and water/soil slurry using Fe0 -modified reactive activated carbon conjugated with persulfate.

Treatment of highly persistent perfluoroalkyl and polyfluoroalkyl substances (PFAS) has been a challenging but significant task. Herein, we propose adsorption-mediated chemical decomposition of PFAS implemented by using granular activated carbon (GAC) impregnated with zerovalent nanoiron (ZVI, Fe0 ), so-called reactive activated carbon (RAC). The effects of reaction temperature, injection of persulfate (PS), and presence of soil on removal of PFAS in water were evaluated. Results showed that RAC conjugated with PS at 60°C exhibited decomposition of PFAS, exclusively all three carboxylic PFAS tested, obviously producing various identifiable short-chain PFAS. Carboxylic PFAS were removed via physical adsorption combined with chemical decomposition while sulfonic PFAS were removed via solely adsorption mechanism. The presence of soil particles did not greatly affect the overall removal of PFAS. Carbon mass balance suggested that chemical oxidation by radical mechanisms mutually influences, in a complex manner, PFAS adsorption to GAC, ZVI and its iron derivatives, and soil particles. Nonetheless, all tested six PFAS were removed significantly. If successfully developed, the adsorption-mediated decomposition strategy may work for treatment of complex media containing PFAS and co-contaminants under different environmental settings. PRACTITIONERS POINTS: Treatment of persistent per- and polyfluoroalkyl substances (PFAS) was addressed. Activated carbon with zerovalent iron was examined in the presence of persulfate. The system significantly removed and decomposed PFAS in water and soil mixture.

Progress and prospect of anodic oxidation for the remediation of perfluoroalkyl and polyfluoroalkyl substances in water and wastewater using diamond electrodes

Although diamond electrodes are widely used in the field of electroanalysis and sensing, their application in the field of environmental engineering has yet to be fully realized. Many research studies have considered their potential application in water and wastewater treatment, where the in-situ electrochemical process can avoid the need for chemical additives by facilitating the oxidation of pollutants on the electrode surface or mediated by electrochemically synthesized oxidants in solution. Diamond-based electro-oxidation can effectively treat a number of organic micropollutants and is now being evaluated for the abatement of perfluoroalkyl and polyfluoroalkyl substances, which pose health concerns and are ubiquitous recalcitrant environmental contaminants. To move implementation of diamond-based electro-oxidation forward, the integration of modifications and codopants to yield more advanced electrode materials needs to be further developed and understood. The progress and current strategies associated with diamond electrode modifications for perfluoroalkyl and polyfluoroalkyl substances abatement as well as future considerations are discussed.

Screening for Per- and Polyfluoroalkyl Substances in Water with Particle Induced Gamma-Ray Emission Spectroscopy

Screening for Per- and Polyfluoroalkyl Substances in Water with Particle Induced Gamma-Ray Emission Spectroscopy