Efficient photodegradation of perfluoroalkyl substances under visible light by hexagonal ZnIn2S4 nanosheets.

Perfluoroalkyl substances (PFASs) are typical persistent organic pollutants, and their removal is urgently required but challenging. Photocatalysis has shown potential in PFASs degradation due to the redox capabilities of photoinduced charge carriers in photocatalysts. Herein, hexagonal ZnIn2S4 (ZIS) nanosheets were synthesized by a one-pot oil bath method and were well characterized by a series of techniques. In the degradation of sodium p-perfluorous nonenoxybenzenesulfonate (OBS), one kind of representative PFASs, the as-synthesized ZIS showed activity superior to P25 TiO2 under both simulated sunlight and visible-light irradiation. The good photocatalytic performance was attributed to the enhanced light absorption and facilitated charge separation. The pH conditions were found crucial in the photocatalytic process by influencing the OBS adsorption on the ZIS surface. Photogenerated e- and h+ were the main active species involved in OBS degradation in the ZIS system. This work confirmed the feasibility and could provide mechanistic insights into the degradation and defluorination of PFASs by visible-light photocatalysis.

Rejection of PFAS and priority co-contaminants in semiconductor fabrication wastewater by nanofiltration membranes.

Use of high-pressure membranes is an effective means for removal of per-and polyfluoroalkyl substances (PFAS) that is less sensitive than adsorption processes to variable water quality and specific PFAS structure. This study evaluated the use of nanofiltration (NF) membranes for the removal of PFAS and industry relevant co-contaminants in semiconductor fabrication (fab) wastewater. Initial experiments using a flat sheet filtration cell determined that the NF90 (tight NF) membrane provided superior performance compared to the NF270 (loose NF) membrane, with NF90 rejection values exceeding 97 % for all PFAS evaluated, including the ultrashort trifluoromethane sulfonic acid (TFMS). Cationic fab co-contaminants diaryliodonium (DIA), triphenylsulfonium (TPS), and tetramethylammonium hydroxide (TMAH) were not as highly rejected as anionic PFAS likely due to electrostatic effects. A spiral wound NF90 module was then used in a pilot system to treat a lab solution containing PFAS and co-contaminants and fab wastewater effluent. Treatment of the fab wastewater, containing high concentrations of perfluorocarboxylic acids (PFCAs), including trifluoroacetic acid (TFA: 96,413 ng/L), perfluoropropanoic acid (PFPrA: 11,796 ng/L), and perfluorobutanoic acid (PFBA: 504 ng/L), resulted in ≥92 % rejection of all PFAS while achieving 90 % water recovery in a semi-batch configuration. These findings demonstrate nanofiltration as a promising technology option for incorporation in treatment trains targeting PFAS removal from wastewater matrices.

Programming of a Portable Digital Monitoring System-Integrated DNA Aptamer Reversely Regulated Oxidase-Like Nanozyme for Real-Time Dynamic Analysis of Atmospheric Perfluorooctanoic Acid.

Timely and efficient analysis of the fluorinated per- and polyfluoroalkyl substances (PFAS) in an atmospheric environment is critical to environmental pollution traceability, early warnings, and governance. Here, a portable, reliable, and intelligent digital monitoring device for onsite real-time dynamic analysis of atmospheric perfluorooctanoic acid (PFOA) is proposed. The sensing mechanism is attributed to the oxidase-like activity of PtCoNPs@g-C3N4 that is reversely regulated by the surface modification of a PFOA-recognizable DNA aptamer, engineering a PFOA-activated oxidase-like activity of nanozyme (Apt-PtCoNPs@g-C3N4) to combine the nonfluorescence o-phenylenediamine (OPD) as the dual-modality response system. The present PFOA interacts with its DNA aptamer and dissociates from the surface of Apt-PtCoNPs@g-C3N4, restoring the oxidase-like activity of PtCoNPs@g-C3N4 to oxidize OPD into yellow fluorescence 2,3-diphenylaniline (DAP), thereby observing a PFOA-triggered colorimetric as well as fluorescence dual-modality change. Then, a hydrogel kit-programmed Apt-PtCoNPs@g-C3N4 + OPD system is used as the sensitive element to incorporate into this homemade portable device, automatically gathering and processing the PFOA-triggered hydrogel colorimetric and fluorescence image gray values by our self-weaving software, ultimately realizing the onsite real-time dynamic analysis of atmospheric PFOA surrounding a fluorochemical production plant. This work provides a direction and theoretical foundation for designing portable onsite screening devices that cater to other atmospheric contaminants detection requirements.

Large-Scale Screening of Per- and Polyfluoroalkyl Substance Binding Interactions and Their Mixtures with Nuclear Receptors.

Despite their significant impact, comprehensive screenings and detailed analyses of per- and polyfluoroalkyl substance (PFAS) binding strengths at the orthosteric and allosteric sites of NRs are currently lacking. This study addresses this gap by focusing on the binding interaction analysis of both common and uncommon PFAS with the nuclear receptors (NRs) vitamin D receptor (VDR), peroxisome proliferator-activated receptor gamma (PPARγ), pregnane X receptor (PXR), and estrogen receptor alpha (ERα). Advanced docking simulations were used to screen 9507 PFAS chemicals at the orthosteric and allosteric sites of PPARγ, PXR, VDR, and ERα. All receptors exhibited strong binding interactions at the orthosteric and allosteric site with a significant number of PFAS. We verified the accuracy of the docking protocol through multiple docking controls and validations. A mixture modeling analysis indicates that PFAS can bind in various combinations with themselves and endogenous ligands simultaneously, to disrupt the endocrine system and cause carcinogenic responses. These findings reveal that PFAS can interfere with nuclear receptor activity by displacing endogenous or native ligands by binding to the orthosteric and allosteric sites. The purpose of this study is to explore the mechanisms through which PFAS exert their endocrine-disrupting effects, potentially leading to more targeted therapeutic strategies. Importantly, this study is the first to explore the binding of PFAS at allosteric sites and to model PFAS mixtures at nuclear receptors. Given the high concentration and persistence of PFAS in humans, this study further emphasizes the urgent need for further research into the carcinogenic mechanisms of PFAS and the development of therapeutic strategies that target nuclear receptors.

Adsorption behaviors of perfluorooctanoic acid on aged microplastics.

The presence of perfluoroalkyl substances (PFAS) in the environment poses a significant threat to ecological safety and environmental health. Widespread microplastics (MPs) have been recognized as vectors for emerging contaminants due to human activities. However, the adsorption behaviors of PFAS on MPs, especially on aged MPs, have not been extensively investigated. This study aimed to investigate the adsorption behaviors of perfluorooctanoic acid (PFOA) on aged MPs (polystyrene, polyethylene, and polyethylene terephthalate) treated with UV irradiation and persulfate oxidation under salinity and dissolve organic matter (DOM) condition. Carbonyl index values of MPs increased after the aged treatment, indicating the production of oxygen-containing groups. The PFOA adsorption on aged MPs was impacted by the co-existence of Na+ ions and DOM. As PFOA adsorption onto aged MPs was mainly controlled by hydrophobic interaction, the electrostatic interaction also made a contribution, but there was no significant change in PFOA adsorption behavior between the pristine and aged MPs. While these findings provide insight into PFAS adsorption on aged MPs, further research is necessary to account for the complexity of the real environment. PRACTITIONER POINTS: Adsorption behaviors of perfluorooctanoic acid (PFOA) on aged microplastics were investigated. Hydrophobic interaction mainly controlled PFOA adsorption on aged microplastics (MPs). Co-existence dissolve organic matter and salinity influenced PFOA adsorption behaviors on aged MPs.

Generic method for the detection of short & long chain PFAS extended to the lowest concentration levels of SERS capability.

The detection of the highly toxic per- and polyfluoroalkyl substances, PFAS, constitutes a challenging task in terms of developing a generic method that could be rapid and applicable simultaneously to both long and short-chain PFAS at ppt concentration level. In the present study, the method introduced by the USA Environmental Protection Agency, EPA, to detect surfactants, using methylene blue, MB, which is identified an ideal candidate for PFAS-MB ion pairing, is extended at the lowest concentration range by a simple additional step that involves the dissociation of the ion pairs in water. In this work, Surface Enhanced Raman Scattering, SERS, is applied via Ag nanocolloidal suspensions to probe MB and indirectly either/or both short-chain (perfluorobutyric acid, PFBA) and long-chain (perfluoloctanoic acid, PFOA) PFAS downt to 5 ppt. This method, which can be further optimized to sub-ppt level via a custom-made SERS-PFAS dedicated Raman system, offers the possibility to be applied to either specific PFAS (both short and long-chain) in a targeted analysis or to total PFAS in a non-targeted analysis at very low detection limits, following any type of MB detection method in aqueous solutions and obviously with any type of SERS substrate.

Super-resistance of PFOS in water: Is it beatable?

In this study, we present research on PFOS occurrence in surface and groundwater in Croatia. PFOS was detected and quantified at ultra-low concentrations (even ng/L) by means of LC-QTOF-MS analysis. PFOS was treated with solar photocatalysis using different reactor types, different irradiation intensities and photocatalytic formulations. Most experiments ended with only a slight change in PFOS concentrations, proving its super-resistance toward UV irradiation and oxidative species, e.g. OH radicals. In certain experiments, PFOS degradation extents were approximately 20% after 120 min of the photocatalytic process. Additionally, photocatalysis was coupled with ultrasound to increase PFOS degradation products, we discussed the tentative degradation mechanism and proposed a solution how to possibly beat its super-resistance.

Non-target discovery and risk prediction of per- and polyfluoroalkyl substances (PFAS) and transformation products in wastewater treatment systems.

Wastewater treatment plants (WWTPs) serve as the main destination of many wastes containing per- and polyfluoroalkyl substances (PFAS). Here, we investigated the occurrence and transformation of PFAS and their transformation products (TPs) in wastewater treatment systems using high-resolution mass spectrometry-based target, suspect, and non-target screening approaches. The results revealed the presence of 896 PFAS and TPs in aqueous and sludge phases, of which 687 were assigned confidence levels 1-3 (46 PFAS and 641 TPs). Cyp450 metabolism and environmental microbial degradation were found to be the primary metabolic transformation pathways for PFAS within WWTPs. An estimated 52.3 %, 89.5 %, and 13.6 % of TPs were believed to exhibit persistence, bioaccumulation, and toxicity effects, respectively, with a substantial number of TPs posing potential health risks. Notably, the length of the fluorinated carbon chain in PFAS and TPs was likely associated with increased hazard, primarily due to the influence of biodegradability. Ultimately, two high riskcompounds were identified in the effluent, including one PFAS (Perfluorobutane sulfonic acid) and one enzymatically metabolized TP (23-(Perfluorobutyl)tricosanoic acid@BTM0024_cyp450). It is noteworthy that the toxicity of some TPs exceeded that of their parent compounds. The results from this study underscores the importance of PFAS TPs and associated environmental risks.

Multicomponent and Surface Charge Effects on PFOS Sorption and Transport in Goethite-Coated Porous Media under Variable Hydrochemical Conditions.

Perfluorooctanesulfonate (PFOS), a toxic anionic perfluorinated surfactant, exhibits variable electrostatic adsorption mechanisms on charge-regulated minerals depending on solution hydrochemistry. This work explores the interplay of multicomponent interactions and surface charge effects on PFOS adsorption to goethite surfaces under flow-through conditions. We conducted a series of column experiments in saturated goethite-coated porous media subjected to dynamic hydrochemical conditions triggered by step changes in the electrolyte concentration of the injected solutions. Measurements of pH and PFOS breakthrough curves at the outlet allowed tracking the propagation of multicomponent reactive fronts. We performed process-based reactive transport simulations incorporating a mechanistic network of surface complexation reactions to quantitatively interpret the geochemical processes. The experimental and modeling outcomes reveal that the coupled spatio-temporal evolution of pH and electrolyte fronts, driven by the electrostatic properties of the mineral, exerts a key control on PFOS mobility by determining its adsorption and speciation reactions on goethite surfaces. These results illuminate the important influence of multicomponent transport processes and surface charge effects on PFOS mobility, emphasizing the need for mechanistic adsorption models in reactive transport simulations of ionizable PFAS compounds to determine their environmental fate and to perform accurate risk assessment.

Rapid adsorptive removal of emerging and legacy per- and polyfluoroalkyl substances (PFASs) from water using zinc chloride-modified litchi seed-derived biochar.

The present study successfully synthesized a novel biochar adsorbent (M-L-BC) using litchi seed modified with zinc chloride for PFASs removal in water. M-L-BC greatly enhanced removal of all examined PFASs (>95 %) as compared to the pristine biochar (<40 %). The maximum adsorption capacity was observed for PFOS, reaching 29.6 mg/g. Adsorption kinetics of PFASs followed the pseudo-second-order model (PSO), suggesting the predominance of chemical adsorption. Moreover, characterization and density functional theory (DFT) calculations jointly revealed involvement of surface complexation, electrostatic interactions, hydrogen bonding, and hydrophobic interactions in PFAS adsorption. Robust PFAS removal was demonstrated for M-L-BC across a wide range of pH (3-9), and coexisting ions had limited impact on adsorption of PFASs except PFBA. Furthermore, M-L-BC showed excellent performance in real water samples and retained reusability after five cycles of regeneration. Overall, M-L-BC represents a promising and high-quality adsorbent for efficient and sustainable removal of PFASs from water.

Enhanced sorption and destruction of PFAS by biochar-enabled advanced reduction process.

The biochar-enabled advanced reduction process (ARP) was developed for enhanced sorption (by biochar) and destruction of PFAS (by ARP) in water. First, the biochar (BC) was functionalized by iron oxide (Fe3O4), zero valent iron (ZVI), and chitosan (chi) to produce four biochars (BC, Fe3O4-BC, ZVI-chi-BC, and chi-BC) with improved physicochemical properties (e.g., specific surface area, pore structure, hydrophobicity, and surface functional groups). Batch sorption experimental results revealed that compared to unmodified biochar, all modified biochars showed greater sorption efficiency, and the chi-BC performed the best for PFAS sorption. The chi-BC was then selected to facilitate reductive destruction and defluorination of PFAS in water by ARP in the UV-sulfite system. Adding chi-BC in UV-sulfite ARP system significantly enhanced both degradation and defluorination efficiencies of PFAS (up to ∼100% degradation and ∼85% defluorination efficiencies). Radical analysis using electron paramagnetic resonance (EPR) spectroscopy showed that sulfite radicals dominated at neutral pH (7.0), while hydrated electrons (eaq-) were abundant at higher pH (11) for the efficient destruction of PFAS in the ARP system. Our findings elucidate the synergies of biochar and ARP in enhancing PFAS sorption and degradation, providing new insights into PFAS reductive destruction and defluorination by different reducing radical species at varying pH conditions.

Effect of short-term sample storage and preparatory conditions on losses of 18 per- and polyfluoroalkyl substances (PFAS) to container materials.

There is a lack of agreement on a suitable container material for per- and polyfluoroalkyl substances (PFAS) analysis, particularly at trace levels. In this study, the losses of 18 short- and long-chain (C4-C10) PFAS to commonly used labware materials (high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polypropylene co-polymer (PPCO), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and glass were investigated. The influence of sample storage and preparation conditions, i.e., storage time, solvent composition, storage temperatures (4 °C and 20 °C), and sample agitation techniques (shaking and centrifugation) on PFAS losses to the container materials were investigated. The results showed higher losses for most of the considered PFAS (up to 50.9%) in 100% aqueous solutions after storage for 7 days regardless of the storage temperature compared to those after 3 days. Overall, the order of losses to different materials varied for individual PFAS, with the highest losses of long-chain PFAS observed to PP and HDPE after 7-day storage at room temperature. The addition of methanol to aqueous PFAS solutions reduced the losses of long-chain PFAS to all tested materials. The use of sample centrifugation and shaking did not influence the extent of losses for most of the PFAS in 80:20 water:methanol (%, v/v) to container materials except for 8:2 fluorotelomer sulfonic acid (8:2 FTS), 9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS), perfluorodecanoic acid (PFDA) and 4:2 fluorotelomer sulfonic acid (4:2 FTS). This study demonstrates lower losses of both long- and short-chain PFAS to glass and PET. It also highlights the need for caution when deciding on sample preparatory steps and storage during the analysis of PFAS.

Vesicles exhibit high-performance removal of per-and polyfluoroalkyl substances (PFAS) depending on their hydrophobic groups.

The removal of per- and polyfluoroalkyl substances (PFAS) from drinking water is urgently needed. Here, we demonstrated high performance of vesicles on PFAS adsorption. Vesicles used in this study were enclosed amphiphile bilayers keeping their hydrophobic groups inside and their hydrophilic groups outside in water. The distribution coefficient Kd of perfluorooctane sulfonic acid (PFOS) for vesicles was 5.3 × 105 L/kg, which is higher than that for granulated activated carbon (GAC), and Kd of perfluorooctanoic acid (PFOA) for vesicles was 103-104 L/kg. The removal efficiencies of PFOA and PFOS adsorption on DMPC vesicles were 97.1 ± 0.1% and 99.4 ± 0.2%, respectively. The adsorption behaviors of PFOA and PFOS on vesicles were investigated by changing the number of cis-double bonds in the hydrophobic chains of the vesicle constituents. Moreover, vesicles formed by membranes in the different phases were also tested. The results revealed that, when vesicles are formed of a membrane in the liquid-crystalline (liquid-like) phase, the adsorption amounts of both PFOA and PFOS increased as the cis-double bond in the hydrocarbon chains decreased, which is considered due to molecular shape similarity. When vesicles are formed of a membrane in the gel (solid-like) phase, they do not adsorb PFAS as much as in the liquid-crystalline phase, even though the hydrocarbon chains do not have any cis-double bond. Our findings demonstrate that vesicles can be utilized as PFAS adsorbents by optimizing the structure of vesicle constituents and their thermodynamical phase. Indeed, the vesicles (DMPC) were demonstrated that they can adsorb PFOA and PFOS, and be coagulated by a coagulant even in environmental water. The coagulation will enable the removal of PFOA and PFOS from the water after adsorption.

Per- and polyfluoroalkyl substances removal from landfill leachate by a planting unit via interactions between foamed glass and Typha domingensis.

Sustainable removal of per- and polyfluoroalkyl substances (PFAS) from landfill leachate remains a pressing global challenge. To develop an effective PFAS removal technology that utilizes nature-based solutions, we considered a planting unit comprised of a microbial carrier (foamed glass) and Typha domingensis. This study evaluated the possibility of removing PFAS from landfill leachate using a planting unit through a pot experiment. The planting unit effectively removed various short- and long-chain PFAS from the landfill leachate, including perfluorocarboxylic acids (PFCAs [C4-C10]), perfluorosulfonic acids (PFSAs [C4, C6, and C8]), fluorotelomer carboxylic acids (FTCAs [5:3 and 7:3]), and 6:2 fluorotelomer sulfonic acid (FTS), with initial concentrations of 43-9100 ng L-1, achieving a removal efficiency of 53-83% in 21 d. Mass balance analysis indicated that the contribution of accumulation on foamed glass and plant adsorption and uptake played no major role in the removal of PFCAs (C4-C9), PFSAs (C4), and FTCAs (5:3 and 7:3), and that other removal processes played a key role. Although not the most effective removal process, the contribution of accumulation on foamed glass tended to be more notable in the removal of longer-chain PFCAs. In addition, plant adsorption and uptake showed that longer-chain PFCAs were more likely to remain in roots, whereas shorter-chain PFCAs were more likely to be transferred to aboveground plant part. On the other hand, 6:2 FTS removal occurred primarily due to accumulation on foamed glass. These results suggest that differences in the physicochemical properties of PFAS affect removal mechanisms. This study provides valuable insights into development of environmentally friendly technologies capable of removing a variety of short- and long-chain PFAS.

Effect of electrolyte composition on electrocatalytic transformation of perfluorooctanoic acid (PFOA) in high pH medium.

Recent regulatory actions aim to limit per- and polyfluoroalkyl substances (PFAS) concentrations in drinking water and wastewaters. Regenerable anion exchange resin (AER) is an effective separation process to remove PFAS from water but will require PFAS post-treatment of the regeneration wastestream. Electrocatalytic (EC) processes using chemically boron-doped diamond electrodes, stable in a wide range of chemical compositions show potential to defluorinate PFOA in drinking water and wastewater treatments. Chemical composition and concentration of mineral salts in supporting electrolytes affect AER regeneration efficiency, and play a crucial role in the EC processes. Their impact on PFAS degradation remains understudied. This study investigates the impact of 17 brine electrolytes with different compositions on perfluorooctanoic acid (PFOA) degradation in an alkaline medium and explores the correlation between the rate of PFOA degradation and the solution's conductivity. Results show that higher electrolyte concentrations and conductivity lead to faster PFOA degradation rates. The presence of chloride anions have negligible impact on the degradation rate. However, the presence of nitrate salts reduce PFOA degradation efficiency. Additionally, the use of mixed electrolytes may be a promising approach for reducing the cost of EC operations. PFOA degradation was not influenced by the pH of the bulk solution.

Lanthanide metal-organic frameworks as ratiometric fluorescent probes for real-time monitoring of PFOA photocatalytic degradation process.

The assessment of perfluorooctanoic acid (PFOA) photocatalytic degradation usually involves tedious pre-treatment and sophisticated instrumentation, making it impractical to evaluate the degradation process in real-time. Herein, we synthesized a series of lanthanide metal-organic frameworks (Ln-MOFs) with outstanding fluorescent sensing properties and applied them as luminescent probes in the photocatalytic degradation reaction of PFOA for real-time evaluation. As the catalytic reaction proceeds, the fluorescence color changes significantly from green to orange-red due to the different interaction mechanisms between the electron-deficient PFOA and smaller radius F- with the ratiometric fluorescent probe MOF-76 (Tb: Eu = 29:1). The limit of detection (LOD) was calculated to be 0.0127 mM for PFOA and 0.00746 mM for F-. In addition, the conversion rate of the catalytic reaction can be read directly based on the chromaticity value by establishing a three-dimensional relationship graph of G/R value-conversion rate-time (G/R indicates the ratio between green and red luminance values in the image.), allowing for real-time and rapid tracking of the PFOA degradation. The recoveries of PFOA and F- in the actual water samples were 99.3-102.7% (RSD = 2.2-4.4%) and 100.7-105.3% (RSD = 3.9-6.8%), respectively. Both theoretical calculations and experiments reveal that the detection mechanism was attributed to the photoinduced electron transfer and energy transfer between the analytes and the probe. This method simplifies the sample analysis process and avoids the use of bulky instruments, and thus has great potential on the design and development of quantitative time-resolved visualization methods to assess catalytic performance and reveal mechanisms.

Temperature-Responsive "Nano-to-Micro" Transformed Polymersomes for Enhanced Ultrasound/Fluorescence Dual Imaging-Guided Tumor Phototherapy.

The perfect integration of microbubbles for efficient ultrasound imaging and nanocarriers for intelligent tumor-targeting delivery remains a challenge in precise tumor theranostics. Herein, we exquisitely fabricated laser-activated and targeted polymersomes (abbreviated as FIP-NPs) for simultaneously encapsulating the photosensitizer indocyanine green (ICG) and the phase change agent perfluorohexane (PFH). The formulated FIP-NPs were nanosize and effectively accumulated into tumors as observed by ICG fluorescence imaging. When the temperature rose above 56 °C, the encapsulated PFH transformed from liquid to gas and the FIP-NPs underwent balloon-like enlargement without structure destruction. Impressively, the enlarged FIP-NPs fused with adjacent polymersomes to form even larger microparticles. This temperature-responsive "nano-to-micro" transformation and fusion process was clearly demonstrated, and FIP-NPs showed greatly improved ultrasound signals. More importantly, FIP-NPs achieved dramatic antitumor efficacy through ICG-mediated phototherapy. Taken together, the novel polymersomes achieved excellent ultrasound/fluorescence dual imaging-guided tumor phototherapy, providing an optimistic candidate for the application of tumor theranostics.

Mechanisms of heating-electrokinetic co-driven perfluorooctanoic acid (PFOA) adsorption on zeolite.

Slow release of emerging contaminants limits their accessibility from soil to pore water, constraining the treatment efficiency of physio-chemical treatment sites. DC fields mobilize organic contaminants and influence their interactions with geo-matrices such as zeolites. Poor knowledge, however, exists on the joint application of heating and electrokinetic approaches on perfluorooctanoic acid (PFOA) transport in porous media. Here, we investigated electrokinetic PFOA transport in zeolite-filled percolation columns at varying temperatures. Variations of pseudo-second-order kinetic constants (kPSO) were correlated to the liquid viscosity variations (η) and elctroosmotic flow velocities (vEOF). Applying DC fields and elevated temperature significantly (>37%) decreased PFOA sorption to zeolite. A good correlation between η, vEOF, and kPSO was found and used to develop an approach interlinking the three parameters to predict the joint effects of DC fields and temperature on PFOA sorption kinetics. These findings may give rise to future applications for better tailoring PFOA transport in environmental biotechnology.

Bacterial degradation of perfluoroalkyl acids.

Advances in biological degradation of per- and polyfluoroalkyl substances (PFAS) have shown that bioremediation is a promising method of PFAS mineralization; however, most of these studies focus on remediation of more reactive polyfluorinated compounds. This review focuses on the defluorination of the more recalcitrant perfluorinated alkyl acids (PFAAs) by bacteria. We highlight key studies that report PFAA degradation products, specific bacteria, and relevant genes. Among these studies, we discuss trends in anaerobic versus aerobic conditions with specific bacterial species or consortia. This holistic review seeks to elucidate the state of PFAA biodegradation research and discuss the need for future research for environmental application.

Synergistic material-microbe interface toward deeper anaerobic defluorination.

Per- and polyfluoroalkyl substances (PFAS), particularly the perfluorinated ones, are recalcitrant to biodegradation. By integrating an enrichment culture of reductive defluorination with biocompatible electrodes for the electrochemical process, a deeper defluorination of a C6-perfluorinated unsaturated PFAS was achieved compared to the biological or electrochemical system alone. Two synergies in the bioelectrochemical system were identified: i) The in-series microbial-electrochemical defluorination and ii) the electrochemically enabled microbial defluorination of intermediates. These synergies at the material-microbe interfaces surpassed the limitation of microbial defluorination and further turned the biotransformation end products into less fluorinated products, which could be less toxic and more biodegradable in the environment. This material-microbe hybrid system brings opportunities in the bioremediation of PFAS driven by renewable electricity and warrants future research on mechanistic understanding of defluorinating and electroactive microorganisms at the material-microbe interface for system optimizations.