Effect of temperature on the sorption and desorption of perfluorooctane sulfonate on humic acid

Sorption and desorption of perfluorooctane sulfonate （PFOS） on humic acid at different temperatures were studied. It was found that the sorption process could be modeled with power kinetic equation very well, suggesting that diflusion predominated the sorption of PFOS on the humic acid. The sorption capacity was doubled when the temperature increased from 5 to 35°C, and thermodynamics parameters △G0 was calculated to be –7.11 to –5.04 kJ/mol, △H0 was 14.2 kJ/mol, and △S 0 was 69.5 J/（mol·K）, indicating that the sorption was a spontaneous, endothermic, and entropy driven process. Desorption hysteresis occurred at all studied temperatures which suggested that humic acid may be an important sink of PFOS in the environment.

Acute toxicity effects of perfluorooctane sulfonate on sperm vitality,kinematics and fertilization success in zebrafish

Perfluorooctane sulfonate （PFOS） has emerged as one of the most concerning contaminants in recent years. This study aimed to investigate the acute toxicity effect of PFOS on sperm viability, kinematics and fertilization success in zebrafish （Danio rerio）. Sperm were activated in aqueous media containing a range of PFOS concentrations （0, 0.09, 0.9 and 9 mg/L）. Viabilities and kinematics of the sperm exposed to different PFOS treatments were assessed via computer-assisted sperm analysis （CASA） at 20, 40, 60, and 80 s after activation. PFOS exposure decreased the percentage of motile sperm, the curvilinear velocity （VCL）, and the mean angular displacement （MAD） of spermatozoa, but showed no influence on the straight- line velocity （VSL） or the angular path velocity （VAP）. Furthermore, a significant decrease in fertilization success was observed in spermatozoa that were exposed to 0.9 mg/L PFOS or more. These findings indicate that PFOS pollution in natural aquatic environment may be a potential threaten to successful reproduction of fish.

Toxicity of perfluorononanoic acid and perfluorooctane sulfonate to Daphnia magna

In order to study toxicological effects of perfluorononanoic acid （PFNA）, perfluorooctane sulfonate （PFOS）, and their mixtures （PFNA/ PFOS） on Daphnia magna （D. magna）, a suite of comprehensive toxicity tests were conducted, including a 48-h acute toxicity test, a 21-day chronic test, a feeding experiment, and a biomarker assay. D. magna were exposed to aqueous solutions of PFNA and PFOS （alone and in combination） at concentrations ranging from 0.008 to 5 mg/L. The survival, growth, and reproduction of D. magna were monitored over a 21- day life cycle. The biomarkers, including acetylcholinesterase （ACHE）, superoxide dismutase （SOD）, and catalase （CAT） activities, were determined after seven days of exposure. PFOS was more toxic than PFNA based on the results of the acute toxicity test. Perfluorinated compounds （PFCs） inhibited both growth and reproduction of D. magna during the testing period. The ingestion rates and the biomarkers, including ACHE, SOD, and CAT activities, were significantly inhibited by PFCs in most cases. Moreover, the combined effects related to the growth and reproduction showed the antagonistic effects of PFCs.

Prenatal Exposure to Perfluorooctane Sulfonate impairs Placental Angiogenesis and Induces Aberrant Expression of LncRNA Xist

Perfluorooctane sulfonate （PFOS） is a class of stable organic compounds with wide industrial,commercial, and consumer applications, such as in textiles, paper, pesticides, and shampoos;. It is readily absorbed, but poorly eliminated, with the elimination half-life of approximately 5 years;.Hence, there have been concerns regarding its potential damage to human health. Some studies

Characterization of Perfluorooctane Sulfonate by Gas Chromatography/Mass Spectrometry

With quantitative conversion to volatile derivatives,substance such as perfluorooctane sulfonate(PFOS)that is difficult to analyze can be separated by conventional techniques and then be characterized.In this paper,the methods and procedures in which perfluorooctane sulfonic acids were converted to corresponding sulfonic ester by reaction with triethylorthoacetate(TEOA)in the presence of solvent were described,and then PFOS was analyzed as ethyl ester derivatives.Mass spectra(MS)were generated using electron ionization(EI)mode.And the EI spectra of the volatile derivatives show ions characteristic of both the fluorinated hydrocarbon and the sulfonic ester portion of the molecules.

Toxicity of perfluorooctane sulfonate and perfluorooctanoate

Persistent perfluorinated organic compounds, such as perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are used in a variety of industrial applications. They are very stable in the environment, distribute widely in the global environment and in wild life, and are detected in human sera. Our searches have detected ppt levels of PFOS and PFOA in the surface water of Japan and China; their levels are generally more than ten times higher in city areas. Neither PFOS nor PFOA is removed by the purification process of city water. Both PFOS and PFOA are detected in sera of all the people of Japan and China (about 1000 times as high as those in surface water), and their concentrations are increasing in both countries, especially in China. PFOS and PFOA primarily distribute to the liver and cause the liver toxicity. They also cause developmental toxicity. PFOS which is not genotoxic in a variety of assay system including our in vivo comet assay, induced tumors of the liver, thyroid and mammary gland of rats. PFOA which is weakly carcinogenic is not mutagenic in many studies including our in vivo comet assay.

Microfluidics-generated graphene oxide microspheres and their application to removal of perfluorooctane sulfonate from polluted water

Monodisperse graphene oxide （GO） microspheres were synthesized via microfluidics technology as a novel adsorbent for rapid （in 2 rain） and high efficiency （98%） removal of perfluorooctane sulfonate （PFOS） from water. This novel material is a potential solution for treatment of bioaccumulative organic polluted water. To achieve improved performance, Mg2＋ was introduced into GO, and the metal composite exhibited significantly improved PFOS removal effidency owing to bridging and interaction between Mg~＋ and the PFOS molecules, which was supported by density functional theory and X-ray photoelectron spectroscopy （XPS）. This facile strategy may be extended to the synthesis of other spheres with unique structural features for application in water treatment.

Removal,distribution and plant uptake of perfluorooctane sulfonate(PFOS)in a simulated constructed wetland system

A vertical-flow constructed wetland(VFCW)was used to treat simulated domestic sewage containing perfluorooctane sulfonate(PFOS).The removal rate of PFOS in the domestic sewage was 93%–98%,through soil adsorption and plant uptake,suggesting that VFCWs can remove PFOS efficiently from wastewater.The removal of PFOS in the VFCW was dependent on soil adsorption and plant uptake;moreover,the percentage of soil adsorption was 61%–89%,and was higher than that of the plants uptake(5%–31%).The absorption capacity of Eichhornia crassipes(E.crassipes)(1186.71 mg/kg)was higher than that of Cyperus alternifolius(C.alternifolius)(162.77 mg/kg)under 10 mg/L PFOS,and the transfer factor of PFOS in E.crassipes and C.alternifolius was 0.04 and 0.58,respectively,indicating that PFOS is not easily translocated to leaves from roots of wetland plants;moreover,uptake of PFOS by E.crassipes was more than that of C.alternifolius because the biomass of E.crassipes was more than that of C.alternifolius and the roots of E.crassipes can take up PFOS directly from wastewater while C.alternifolius needs to do so via its roots in the soil.The concentration of 10 mg/L PFOS had an obvious inhibitory effect on the removal rate of total nitrogen,total phosphorus,chemical oxygen demand,and ammonia nitrogen in the VFCW,which decreased by 15%,10%,10%and 12%,respectively.Dosing with PFOS in the wastewater reduced the bacterial richness but increased the diversity in soil because PFOS stimulated the growth of PFOS-tolerant strains.

Selective sorption of perfluorooctane sulfonate on molecularly imprinted polymer adsorbents

Perfluorooctane sulfonate(PFOS),as a potential persistent organic pollutant,has been widely detected in water environments,and has become a great concern in recent years.PFOS is very stable and difficult to decompose using conventional techniques.Sorption may be an attractive method to remove it from water.In this study,the molecularly imprinted polymer(MIP)adsorbents were prepared through the polymerization of 4-vinylpyridine under different preparation conditions in order to remove perfluorooctane sulfonate(PFOS)from water.The MIP adsorbents using perfluorooctanoic acid(PFOA)as the template had good imprinting effects and could selectively remove PFOS from aqueous solution.The sorption behaviors including sorption kinetics,isotherms,and effect of pH,salt,and competitive anions were investigated.Experimental results showed that the sorption of PFOS on the MIP adsorbents was very fast,pHdependent,and highly selective.The achieved fast sorption equilibrium within 1 h was attributed to the surface sorption on the fine adsorbents.The sorption isotherms showed that the sorption selectivity of PFOS on the MIP adsorbents decreased at high PFOS concentrations,which may be due to the double-layer sorption and the formation of PFOS micelles on the sorbent surface.The sorption of PFOS on the MIP adsorbents was mainly dominated by the electrostatic interaction between the protonated vinylpyridine on the adsorbent surface and the anionic PFOS.The prepared MIP adsorbents can potentially be applied in water and wastewater treatment for selective removal of PFOS.

Toxic effect of perfluorooctane sulfonate on plants in vertical-flow constructed wetlands

Per-and polyfluoroalkyl substances(PFASs)can be taken up and bioaccumulated in plants,but the toxic mechanisms of PFASs on wetland plants are still unclear.In present study,the toxic influences of perfluorooctane sulfonate(PFOS)on Eichhornia crassipes(E.crassipes)and Cy perus alternifolius(C.alternifolius)in a vertical-sub surface-flow constructed wetland were evaluated.The results showed that E.crassipes was more tolerant to PFOS stress than C.alternifolius,and the growth and chlorophyll synthesis of the two plants were promoted by low concentration(<0.1 mg/L)of PFOS,and the chlorophyll synthesis was inhibited by high concentration(10 mg/L)of PFOS but the growth did not change obviously.The catalase activity and malondialdehyde content in the leaves of the two plants increased,peroxidase activity decreased under exposure to high concentrations of PFOS,and superoxide dismutase activity did not change.Under PFOS stress,the membrane of plant leaves and the cell structure of the two wetland plants were destroyed,and the mitochondrial contour of root cells became incomplete.Tanscriptomic analysis showed that the expression levels of genes related to cell wall formation,the cell apoptosis pathway,material synthesis,and metabolism in the plants were changed by PFOS.Analysis in fluorogenic quantitative real time polymerase chain reaction(RT-qPCR)also confirmed that the photosynthesis system of E.crassipes was inhibited,while that of C.alternifolius was promoted.

Fluorescence detection of perfluorooctane sulfonate in water employing a tetraphenylethylene-derived dual macrocycle Bowtie Cyclophane

Because the widely used perfluorooctane sulfonate(PFOS) is harmful to both environment and human health, it is of great significance and urgency to develop sensitive and selective sensors for the detection of trace PFOS in water. In this study, a tetraphenylethylene-derived macrocycle Bowtie Cyclophane has been developed as a fluorescent sensor based on aggregation-induced emission enhancement and fluorochromism. Sensitive detection of PFOS has been achieved with a limit of detection(LOD) of47.3 ± 2.0 nmol/L(25.4 ± 1.1 μg/L) accompanied by visual fluorescence color changes.

Sorption of Perfluorooctane sulfonate(PFOS) including its isomers on hydrargillite as a function of pH,humic substances and Na2SO4

Perfluorooctane sulfonate(PFOS)is a persistent organic pollutant(POP)and emergent contaminant that are widespread in the environment.Understanding the mechanisms controlling the distribution of PFOS and its isomers between hydrargillite and the water phase is important in order to study their redistribution and mobility in the environment.This study investigated the effects of pH,humic acid,fulvic acid and Na_(2)SO_(4) on sorption of PFOS isomers to hydrargillite.A mixture of PFOS isomers was spiked into water and hydrargillite was added to the system and shaken for one day;the system was tested with different aqueous composition.Concentrations of PFOS isomers in the aqueous phase were quantified using an ultra-performance liquid chromatograph coupled to a triple quadrupole mass spectrometer.Our results showed that the distribution coefficients of PFOS isomers were found to be 0.76,0.71,0.93 and 0.90 at pH 6.5,for 3-/4-/5-PFOS,6-/2-PFOS,L-PFOS and total PFOS respectively.The distribution coefficients increased at lower pH and decreased at alkaline conditions.The presence of humic substances(HS)increased the sorption slightly at the environmental pH of 6.5,although a competition effect was observed during acidic conditions.A tendency of PFOS distribution to hydrargillite in the presence of Na_(2)SO_(4) was like its behavior in the presence of HS although the mechanisms behind the sorption were interpreted differently.This study revealed that L-PFOS was readily sorbed when no other chemicals were added or in 20 mg/L FA or 100 mg/L Na_(2)SO_(4).We suggest that an increase in PFOS sorption in the presence of HS may be due to hydrophobic mechanisms while Na_(2)SO_(4) contributed to increased sorption through ionic strength effects.

Exposure to perfluorooctane sulfonate reduced cell viability and insulin release capacity of β cells

Per-and polyfluoroalkyl substances(PFAS)are found to have multiple adverse outcomes on human health.Recently,epidemiological and toxicological studies showed that exposure to PFAS had adverse impacts on pancreas and showed association with insulin abnormalities.To explore how PFAS may contribute to diabetes,we studied impacts of perfluorooctane sul-fonate(PFOS)on cell viability and insulin release capacity of pancreatic β cells by using in vivo and in vitro methods.We found that 28-day administration with PFOS(10 mg/(kg body weight·day))caused reductions of pancreas weight and islet size in male mice.PFOS admin-istration also led to lower serum insulin level both in fasting state and after glucose infusion among male mice.For cell-based in vitro bioassay,we used mouse β-TC-6 cancer cells and found 48-hr exposure to PFOS decreased the cell viability at 50 μmol/L.By measuring insulin content in supernatant,48-hr pretreatment of PFOS(100 μmol/L)decreased the insulin re-lease capacity of β-TC-6 cells after glucose stimulation.Although these concentrations were higher than the environmental concentration of PFOS,it might be reasonable for high con-centration of PFOS to exert observable toxic effects in mice considering mice had a faster removal efficiency of PFOS than human.PFOS exposure(50 μmol/L)to β-TC-6 cells induced intracellular accumulation of reactive oxidative specie(ROS).Excessive ROS induced the re-active toxicity of cells,which eventually invoke apoptosis and necrosis.Results in this study provide evidence for the possible causal link of exposure to PFOS and diabetes risk.

Photochemical decomposition of 1H,1H,2H,2H-perfluorooctane sulfonate(6:2FTS)induced by ferric ions

Perfluorooctane sulfonate（PFOS） had wide applications,such as in the electroplating industry,but its use was restricted in 2009 by the Stockholm Convention,due to its environmental persistence and potential hazards.As the most common PFOS alternative,lH,lH,2H,2H-perfluorooctane sulfonic acid（6：2FTS） and its salts have been increasingly used.However,little is known about its photochemical decomposition.This paper reports the ferric ion-induced efficient decomposition and defluorination of 6：2FTS under 254 nm ultraviolet（UV） irradiation;the underlying mechanisms were also investigated.In the presence of 100 ｜imol/L ferric ion and at pH 3.0,the first-order decomposition rate constant of 6：2FTS（10 mg/L） was 1.59/hr,which was 6 times higher than for direct UV photolysis.The effects of the ferric ion concentration and the solution pH on the 6：2FTS photodecomposition were investigated and the optimal reaction conditions were determined.In addition to fluoride and sulfate ions,shorter-chain PFCAs（C2-C7） were detected as major intermediates.The addition of hydrogen peroxide or oxalic acid accelerated the decomposition of 6：2FTS under UV irradiation,but not its defluorination,indicating that hydroxyl radicals can directly react with 6：2FTS but not with the shorter-chain PFCAs.Accordingly,a mechanism for 6：2FTS photochemical decomposition in the presence of ferric ion was proposed,which comprises two reaction pathways.First,hydroxyl radicals can directly attack 6：2FTS,leading to C- C bond cleavage.Alternatively,6：2FTS coordinates with ferric ion to form Fe（III）-6：2FTS complexes,which can undergo ligand-to-metal charge transfer under UV irradiation,causing C-S bond cleavage.

Facile identification of fluorosurfactant category in aqueous film-forming foam concentrates via optimized^(19)F NMR

Aqueous film-forming foams(AFFFs)are the primary source of toxic perfluoroalkyl and polyfluoroalkyl substances(PFAS)in wastewater.Thus,it is urgent to develop a facile and fast method for identifying fluorosurfactants in commercially available AFFFs.In this work,fluorine nuclear magnetic resonance(^(19)F NMR)spectroscopy was optimized to measure AFFFs directly with the extra addition of 5%D_(2)O as the locking reagent,and high-quality spectra could be acquired within 4 min(0.1%fluorosurfactant content).Recovery experiments demonstrated that the use of different AFFFs had no marked influence on the quantitative analysis of fluorosurfactants.Such method works with low-field NMR spectroscopy(1.4 T)as well.Two-dimensional(2D)^(19)F COSY NMR was used to make signal assignments for different fluorosurfactant derivatives.The optimized ^(19)F NMR could quantify the commercially available fluorosurfactants in different AFFFs,identify them being in either the perfluorooctane sulfonate(PFOS)or fluorotelomer sulfonic acid(FTS)categories,and distinguish the head-group of PFOS and FTS derivatives,which exhibits great potentials in the developments of relevant commercial detections.

Perfluorooctane sulfonate promotes the migration of colorectal cancer cells by inducing epithelial-mesenchymal transition

The potential association between colorectal cancer(CRC)and environmental pollutants is worrisome.Previous studies have found that some perfluoroalkyl acids,including perfluorooctane sulfonate(PFOS),induced colorectal tumors in experimental animals and promoted the migration of and invasion by CRC cells in vitro,but the underlying mechanism is unclear.Here,we investigated the effects of PFOS on the proliferation and migration of CRC cells and the potentialmechanisms involving activating the PI3K/Akt-NF-κB signal pathway and epithelial-mesenchymal transition(EMT).It was found that PFOS promoted the growth andmigration of HCT116 cells at non-cytotoxic concentrations and increased the mRNA expression of the migration-related angiogenic cytokines vascular endothelial growth factor(VEGF)and interleukin-8(IL-8).In a mechanistic investigation,the up-stream signal pathway PI3K/Akt-NF-κB was activated by PFOS,and the process was suppressed by LY294002(PI3K/Akt inhibitor)and BAY11-7082(NF-κB inhibitor)respectively,leading to less proliferation of HCT116 cells.Furthermore,matrix metalloproteinases(MMP)and EMT-related markers were up-regulated after PFOS exposure,and were also suppressed respectively by LY294002 and BAY11-7082.Moreover,the up-regulation of EMT markers was suppressed by a MMP inhibitor GM6001.Taken together,our results indicated that PFOS promotes colorectal cancer cell migration and proliferation by activating the PI3K/Akt-NF-κB signal pathway and epithelial-mesenchymal transition.This could be a potential toxicological mechanism of PFOS-induced malignant development of colorectal cancer.

Adsorption of emerging sodium p-perfluorous nonenoxybenzene sulfonate(OBS) onto soils: Kinetics, isotherms and mechanisms

The widespread use of sodium p-perfluorous nonenoxybenzene sulfonate(OBS), a typical alternative to perfluorooctane sulfonate, has resulted in potential threats to the environment, but the adsorption behavior of OBS in soils has not yet been reported. In this study, the adsorption behaviors of OBS on five soils with different physicochemical properties were investigated. The rate of OBS adsorption was fast, and most of the OBS uptake was completed within 12 h. The good model fit of OBS adsorption to the pseudo-second-order and Elovich models indicated the occurrence of chemical adsorption. The adsorption isotherms of OBS on the soils were better described by the Freundlich model than by the Langmuir model, suggesting that the OBS adsorption sites on the soils were heterogeneous. This is possibly associated with various adsorption mechanisms including hydrophobic, π-π, hydrogen bonding, and electrostatic interactions,further confirmed by the good model fit to the D-R isotherm. Adsorption of OBS occurred on the soils, and the adsorption process was spontaneous and endothermic. In addition, the soils were more suitable for OBS adsorption at lower pH values due to the stronger electrostatic adsorption. The OBS adsorption on the soils decreased with the increase of soil depth from 0 to 30 cm. Moreover, the presence of organic matter and ammonia nitrogen in the soils was favorable for OBS adsorption, and these parameters decreased with increasing soil depth, making OBS adsorption less prominent in the deeper soil. This study indicates that OBS is easily enriched in surface soils, and that soil organic matter and ammonia nitrogen significantly affect OBS migration in soil.

Development of a Completely New PFOS Alternative with Lower Surface Tension for Minimizing the Environmental Burden

Improving the technical performance of related industrial products is an efficient strategy to reducing the application quantities and environmental burden for toxic chemicals.A novel polyfluoroalkyl surfactant potassium 1,1,2,2,3,3,4,4-octafluoro-4-(perfluorobutoxy)butane-1-sulfonate(F404)was synthesized by a commercializable route.It had a surface tension(γ)of 18.2 mN/m at the critical micelle concentration(CMC,1.04 g/L),significantly lower than that of perfluorooctane sulfonate(PFOS,ca.33.0 mN/m,0.72 g/L),and exhibited remarkable suppression of chromium-fog at a dose half that of PFOS.The half maximal inhibitory concentration(IC_(50))values in HepG2 cells and the lethal concentration of 50%(LC_(50))in zebrafish embryos after 72 hpf indicated a lower toxicity for F404 in comparison to PFOS.In a UV/sulphite system,89.3%of F404 were decomposed after 3 h,representing a defluorination efficiency of 43%.The cleavage of the ether C—O bond during the decomposition would be expected to form a short chain·C_(4)F_(9) as the position of the ether C—O in the F404 fluorocarbon chains is C4—O5.The ether unit is introduced in the perfluoroalkyl chain to improve water solubility,biocompatibility and degradation,thereby minimizing the environmental burden.

Screening ionic liquids for efficiently extracting perfluoroalkyl chemicals (PFACs) from wastewater

Liquid-liquid extraction(LLE)using ionic liquids(ILs)-based methods to remove perfluoroalkyl chemicals(PFACs),such as perfluorooctanoic acid(PFOA)and perfluorooctane sulfonic acid(PFOS),from wastewater,is an important strategy.However,the lack of physicochemical and LLE data limits the selection of the most suitable ILs for the extraction of PFACs.In this work,1763 ILs for PFACs extraction from water were systematically screened using COSMOtherm to estimate the infinite dilution activity coefficient(lnγ^(∞))of PFOA and PFOS in water and ILs.To evaluate the accuracy of COSMOtherm,8 ILs with various lnγ^(∞)values were selected,and their extraction efficiency(E)and distribution coefficient(D_(exp))were measured experimentally.The results showed that the predicted lnγ^(∞)decreased as the increase of experimental extraction efficiency of PFOA or PFOS,while the tendency of predicted distribution coefficient(D_(pre))was consistent with the experimental(D_(exp))results.This work provides an efficient basis for selecting ILs for the extraction of PFACs from wastewater.

Ecotoxicological effects of waterborne PFOS exposure on swimming performance and energy expenditure in juvenile goldfish (Carassius auratus)

The potential risks of perfluorooctane sulfonate （PFOS） are of increasing ecological concern. Swimming performance is linked to the fitness and health of fish. However, the impacts of PFOS on swimming performance remain largely unknown. We investigated the ecotoxicological effects of acute exposure to PFOS on the swimming performance and energy expenditure of juvenile goldfish （Carassius auratus）. The fish were exposed to a range of PFOS concentrations （0, 0.5, 2, 8 and 32 mg/L） for 48 hr. The spontaneous swimming activity, fast-start swimming performance, critical swimming speed （Ucrit） and active metabolic rate （AMR） of the goldfish were examined after exposure to PFOS. PFOS exposure resulted in remarkable effects on spontaneous activity. Motion distance was reduced, and the proportion of motionless time increased with increasing concentrations of PFOS. However, no significant alterations in the fast-start performance-related kinematic parameters, such as latency time, maximum linear velocity, maximum linear acceleration or escape distance during the first 120 msec after stimulus, were observed after PFOS exposure. Unexpectedly, although PFOS exposure had marked influences on the swimming oxygen consumption rates and AMR of goldfish, the U crit of the goldfish was not significantly affected by PFOS. This may result in a noteworthy increase in the energetic cost of transport. The overall results indicate that, in contrast to spontaneous activity, underlying swimming capabilities are maintained in goldfish after short-term exposure to PFOS, but energy expenditure during the process of swimming is dramatically aggravated.