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...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.展开更多
Fluorochemicals(FCs)are oxidatively recalcitrant,environmentally persistent,and resistant to most conventional treatment technologies.FCs have unique physiochemical properties derived from fluorine which is the most e...Fluorochemicals(FCs)are oxidatively recalcitrant,environmentally persistent,and resistant to most conventional treatment technologies.FCs have unique physiochemical properties derived from fluorine which is the most electronegative element.Perfluorooctanesulfonate(PFOS),and perfluorooctanoate(PFOA)have been detected globally in the hydrosphere,atmosphere and biosphere.Reducing treatment technologies such as reverses osmosis,nano-filtration and activated carbon can remove FCs from water.However,incineration of the concentrated waste is required for complete FC destruction.Recently,a number of alternative technologies for FC decomposition have been reported.The FC degradation technologies span a wide range of chemical processes including direct photolysis,photocatalytic oxidation,photochemical oxidation,photochemical reduction,thermally-induced reduction,and sonochemical pyrolysis.This paper reviews these FC degradation technologies in terms of kinetics,mechanism,energetic cost,and applicability.The optimal PFOS/PFOA treatment method is strongly dependent upon the FC concentration,background organic and metal concentration,and available degradation time.展开更多
Perfluorooctanoic acid(PFOA),a novel contaminant,is extensively found in aquatic environments.However,the capability of the denitrifying phosphorus removal process to treat PFOA-containing wastewater,as well as its re...Perfluorooctanoic acid(PFOA),a novel contaminant,is extensively found in aquatic environments.However,the capability of the denitrifying phosphorus removal process to treat PFOA-containing wastewater,as well as its response mechanisms,are unclear.This study used batch experiments to assess the short-term impact of PFOA on denitrifying phosphorus removal systems.During a single cycle,the addition of PFOA predominantly enhanced phosphate removal in the system mainly by the anaerobic phosphorus release pathway,but had no substantial effect on nitrogen removal.COD removal efficiency has a substantial positive correlation with C6-HSL and C8-HSL concentrations.As the PFOA concentration increased,the ROS concentration and enzyme activity also increased,while the PN/PS ratio decreased,causing the sludge to become looser.At the beginning of the second cycle,the impact of PFOA on phosphorus removal efficiency shifted from promotion to inhibition.These findings shed fresh light on the influence of PFOA on the denitrifying phosphorus removal mechanism,potentially furthering its use in the treatment of fluoride-containing wastewater.展开更多
The photodegradation of persistent and bioaccumulative perftuorooctanoic acid （PFOA） in water by 185 nm vacuum ultraviolet （VUV） light was examined to develop an effective technology to deal with PFOA pollution. P...The photodegradation of persistent and bioaccumulative perftuorooctanoic acid （PFOA） in water by 185 nm vacuum ultraviolet （VUV） light was examined to develop an effective technology to deal with PFOA pollution. PFOA degraded very slowly under irradiation of 254 nm UV light. However, 61.7% of initial PFOA was degraded by 185 nm VUV light within 2 h, and defluorination ratio reached 17.1%. Pseudo first-order-kinetics well simulated its degradation and defluorination. Besides, fluoride ion formed in water, 4 shorter-chain perfluorinated carboxylic acids （PFCAs）, that is, perfluoroheptanoic acid, perfluorohexanoic acid, perfluoropentanoic acid, and perfluorobutanoic acid. These were identified as intermediates by LC-MS measurement. These PFCAs consecutively formed and further degraded with irradiation time. According to the mass balance calculation, no other byproducts were formed. It was proposed that PFCAs initially are decarboxylated by 185 nm light, and the radical thus formed reacts with water to form shorter-chain PFCA with one less CF2 unit.展开更多
There is an urgent need for developing cost-effective methods for the treatment of perfluorooctanoic acid(PFOA)due to its global emergence and potential risks.In this study,taking surface-defective BiOCl as an example...There is an urgent need for developing cost-effective methods for the treatment of perfluorooctanoic acid(PFOA)due to its global emergence and potential risks.In this study,taking surface-defective BiOCl as an example,a strategy of surface oxygen vacancy modulation was used to promote the photocatalytic defluorination efficiency of PFOA under simulated sunlight irradiation.The defective BiOCl was fabricated by a fast microwave solvothermal method,which was found to induce more surface oxygen vacancies than conventional solvothermal and precipitation methods.As a result,the asprepared BiOCl showed significantly enhanced defluorination efficiency,which was 2.7 and33.8 times higher than that of BiOCl fabricated by conventional solvothermal and precipitation methods,respectively.Mechanistic studies indicated that the defluorination of PFOA follows a direct hole(h^+)oxidation pathway with the aid of·OH,while the oxygen vacancies not only promote charge separation but also facilitate the intimate contact between the photocatalyst surface and PFOA by coordinating with its terminal carboxylate group in a bidentate or bridging mode.This work will provide a general strategy of oxygen vacancy modulation by microwave-assisted methods for efficient photocatalytic defluorination of PFOA in the environment using sunlight as the energy source.展开更多
Perfluorooctanoic acid （PFOA） is a new-found hazardous persistent organic pollutant, and it is resistant to decomposition by hydroxyl radical （HO.） due to its stable chemical structure and the high electronegativi...Perfluorooctanoic acid （PFOA） is a new-found hazardous persistent organic pollutant, and it is resistant to decomposition by hydroxyl radical （HO.） due to its stable chemical structure and the high electronegativity of fluorine. Photocatalytic reduction of PFOA with β-Ga2O3 in anoxic aqueous solution was investigated for the first time, and the results showed that the photoinduced electron （ecb） coming from the β-Ga2O3 conduction band was the major degradation substance for PFOA, and shorter-chain perfluorinated carboxylic acids （PFCAs, CnF2n＋1COOH, 1 ≤ n ≤ 6） were the dominant products. Furthermore, the concentration of F- was measured by the IC technique and defluorination efficiency was calculated. After 3 hr, the photocatalytic degradation efficiency was 98.8% and defluorination efficiency was 31.6% in the presence of thiosulfate and bubbling N2. The degradation reaction followed first-order kinetics （k = 0.0239 min-1, t1/2 = 0.48 hr）. PFCAs （CnF2n＋xCOOH, 1 ≤ n≤ 7） were detected and measured by LC-MS and LC-MS/MS methods. It was deduced that the probable photocatalytic degradation mechanism involves ec-b attacking the carboxyl of CnF2n＋1COOH, resulting in decarboxylation and the generation of CnFzn＋1. The produced CnF2n＋1 reacted with H2O, forming CnF2n＋1OH, then CnF2n＋1OH underwent HF loss and hydrolysis to form CnF2,＋1COOH.展开更多
Bismuth-based material has been broadly studied due to their potential applications in various areas,especially used as promising photocatalysts for the removal of persistent organic pollutants(POPs) and several appro...Bismuth-based material has been broadly studied due to their potential applications in various areas,especially used as promising photocatalysts for the removal of persistent organic pollutants(POPs) and several approaches have been adopted to tailor their features.Herein,the bismuth-based photocatalysts(BiOCl,BiPO4,BiOPO4/BiOCl) were synthesized by hydrothermal method and advanced characterization techniques(XRD,SEM,EDS elemental mapping,Raman and UV-vis DRS) were employed to analyze their morphology,crystal structure,and purity of the prepared photocatalysts.These synthesized photocatalysts offered a praiseworthy activity as compared to commercial TiO2(P25) for the degradation of model pollutant perfluorooctanoic acid(PFOA) under 254 nm UV light.It was interesting to observe that all synthesized photocatalysts show significant degradation of PFOA and their photocatalytic activity follows the order:bismuth-based catalysts> TiO2(P25)> without catalyst.Bismuth-based catalysts degraded the PFOA by almost 99.99% within 45 min while this degradation efficiency was 66.05% with TiO2 under the same reaction condition.Our work shows that the bismuth-based photocatalysts are promising in PFOA treatment.展开更多
When wood-based activated carbon was tailored with quaternary ammonium/epoxide(QAE) forming compounds(QAE-AC), this tailoring dramatically improved the carbon's effectiveness for removing perfluorooctanoic acid(PF...When wood-based activated carbon was tailored with quaternary ammonium/epoxide(QAE) forming compounds(QAE-AC), this tailoring dramatically improved the carbon's effectiveness for removing perfluorooctanoic acid(PFOA) from groundwater. With favorable tailoring, QAE-AC removed PFOA from groundwater for 118,000 bed volumes before halfbreakthrough in rapid small scale column tests, while the influent PFOA concentration was 200 ng/L. The tailoring involved pre-dosing QAE at an array of proportions onto this carbon, and then monitoring bed life for PFOA removal. When pre-dosing with 1 mL QAE, this PFOA bed life reached an interim peak, whereas bed life was less following 3 mL QAE pre-dosing, then PFOA bed life exhibited a steady rise for yet subsequently higher QAE pre-dosing levels. Large-scale atomistic modelling was used herein to provide new insight into the mechanism of PFOA removal by QAE-AC. Based on experimental results and modelling, the authors perceived that the QAE's epoxide functionalities cross-linked with phenolics that were present along the activated carbon's graphene edge sites, in a manner that created mesopores within macroporous regions or created micropores within mesopores regions. Also, the QAE could react with hydroxyls outside of these pore, including the hydroxyls of both graphene edge sites and other QAE molecules. This latter reaction formed new pore-like structures that were external to the activated carbon grains. Adsorption of PFOA could occur via either charge balance between negatively charged PFOA with positively charged QAE, or by van der Waals forces between PFOA's fluoro-carbon tail and the graphene or QAE carbon surfaces.展开更多
Nanophotocatalysts have shown great potential for degrading poly-and perfluorinated substances(PFAS).In light of the fact that most of these catalysts were studied in pure water,this study was designed to elucidate ef...Nanophotocatalysts have shown great potential for degrading poly-and perfluorinated substances(PFAS).In light of the fact that most of these catalysts were studied in pure water,this study was designed to elucidate effects from common environmental factors on decomposing and defluorinating perfluorooctanoic acid(PFOA)by In2O3 nanoparticles.Results from this work demonstrated that among the seven parameters,pH,sulfate,chloride,H2O2,In2O3 dose,NOM and O2,the first four had statistically significant negative effects on PFOA degradation.Since PFOA is a strong acid,the best condition leading to the highest PFOA removal was identified for two pH ranges.When pH was between 4 and 8,the optimal condition was:pH=4.2;sulfate=5.00 mg/L;chloride=20.43 mg/L;H2O2=0 mmol/L.Under this condition,PFOA decomposition and defluorination were 55.22 and 23.56%,respectively.When pH was between 2 and 6,the optimal condition was:pH=2;sulfate=5.00 mg/L;chloride=27.31 mg/L;H2O2=0 mmol/L.With this condition,the modeled PFOA decomposition was 97.59%with a defluorination of approximately 100%.These predicted results were all confirmed by experimental data.Thus,In2O3 nanoparticles can be used for degrading PFOA in aqueous solutions.This approach works best when the target contaminated water contains low concentrations of NOM,sulfate and chloride and at a low pH.展开更多
Perfluorooctanoic acid(PFOA), its salts, and related compounds were listed as new persistent organic pollutants by the Stockholm Convention in 2019.In this study, the occurrence of residues of PFOA and other per-and p...Perfluorooctanoic acid(PFOA), its salts, and related compounds were listed as new persistent organic pollutants by the Stockholm Convention in 2019.In this study, the occurrence of residues of PFOA and other per-and polyfluoroalkyl substances(PFASs) in raw materials and fluoropolymer products from the Chinese fluoropolymer industries are reported for the first time.The PFOA concentrations in raw materials and fluoropolymer products were in the range of 6.7 to 1.1 × 10^(6) ng/g, and <MDL(method detection limit) to 5.3 × 10^(3) ng/g,respectively.Generally, the levels of PFOA in raw materials were higher than in products,implying that PFOA in the emulsion/dispersion resin could be partly removed during the polymerization or post-processing steps.By tracking a company’s polytetrafluoroethylene(PTFE) production line, it was found that over a 5 year period, the residual levels of PFOA in emulsion samples declined from 1.1 × 10^(6) to 28.4 ng/g, indicating that the contamination of PFOA in fluoropolymer products from production source gradually decreased after its use had been discontinued.High concentrations of HFPO-TrA(2.7 × 10^(5) to 8.2 × 10^(5) ng/g) were detected in some emulsion samples indicating this alternative has been widely applied in fluoropolymer manufacturing in China.展开更多
Environmentally persistent and bioaccumulative perfluorooctanic acid （PFOA） was difficult to be decomposed under the irradiation of 254 nm UV light. However, in the presence of 80μmol/L Fe（Ⅲ）, 80% of PFOA with i...Environmentally persistent and bioaccumulative perfluorooctanic acid （PFOA） was difficult to be decomposed under the irradiation of 254 nm UV light. However, in the presence of 80μmol/L Fe（Ⅲ）, 80% of PFOA with initial concentration of 48μmol/L （20 mg/L） was effectively degraded and 47.8% of fluorine atoms in PFOA molecule were transformed into inorganic fluoride ion after 4 h reaction. Shorter chain perfluorocarboxylic acids bearing C3-C7 and fluoride ion were detected and identified by LC/MS and IC as the degradation products in the aqueous solution. It was proposed that complexes of PFOA with Fe（Ⅲ） initiated degradation of PFOA irradiated with 254 nm UV light.展开更多
Perfluorooctanoic acid（PFOA）is recalcitrant to degrade and mineralize.Here,the effect of temperature on the photolytic decomposition of PFOA was investigated.The decomposition of PFOA was enhanced from 34% to 99% in...Perfluorooctanoic acid（PFOA）is recalcitrant to degrade and mineralize.Here,the effect of temperature on the photolytic decomposition of PFOA was investigated.The decomposition of PFOA was enhanced from 34% to 99% in 60 min of exposure when the temperature was increased from 25 to 85℃ under UV light（201–600 nm）.The limited degree of decomposition at 25℃ was due to low quantum yield,which was increased by a factor of 12 at 85℃.Under the imposed conditions,the defluorination ratio increased from 8% at 25℃ to 50% at85℃ in 60 min.Production of perfluorinated carboxylic acids（PFCAs,C7–C5）,PFCAs（C4–C3）and TFA（trifluoroacetic acid,C2）accelerated and attained a maximum within 30 to 90 min at 85℃.However,these reactions did not occur at 25℃ despite extended irradiation to180 min.PFOA was decomposed in a step-wise process by surrendering one CF2unit.In each cyclical process,increased temperature enhanced the quantum yields of irradiation and reactions between water molecules and intermediates radicals.The energy consumption for removing eachμmol of PFOA was reduced from 82.5 k J at 25℃ to 10.9 k J at 85℃ using photolysis.Photolysis coupled with heat achieved high rates of PFOA degradation and defluorination.展开更多
Nanofiltration(NF)process has become one of the most promising technologies to remove micro-organic combined water pollution.Developing a NF membrane material with efficient separation for perfluorooctanoic acid(PFOA)...Nanofiltration(NF)process has become one of the most promising technologies to remove micro-organic combined water pollution.Developing a NF membrane material with efficient separation for perfluorooctanoic acid(PFOA)combined pollution is highly desired,this manuscript targets this unmet need specifically.In this work,hydrophilic SiO_(2)nanoparticles with various contents blended with carboxylic multiwalled carbon nanotube were used to modify poly(m-phenylene isophthal amide)(SiO_(2)/CMWCNT/PMIA)hollow fiber NF membrane.The modified membrane with 0.1 wt%SiO_(2)doping exhibits way better fouling resistance with irreversible fouling ratio decreased dramatically from 18.7%to 2.3%,and the recovery rate of water flux increases significantly from 81.2%to 97.7%.The separation experiment results had confirmed that the modified membrane could improve the rejection from 97.2%to 98.6%for perfluorooctanoic acid(PFOA)and its combined pollution with bovine serum albumin(BSA).It is clear that this reported SiO_(2)/CMWCNT/PMIA hollow fiber NF membrane potentially could be applied in water treatment.This research also provides a theoretical basis for efficiently removal of PFOA and its combined pollution by NF membrane.展开更多
Aqueous perfluorooctanoic acid(PFOA)elimination has raised significant concerns due to its persistence and bioaccumulation.Althoughβ-PbO_(2)plate anodes have shown efficient mineralization of PFOA,it remains unclear ...Aqueous perfluorooctanoic acid(PFOA)elimination has raised significant concerns due to its persistence and bioaccumulation.Althoughβ-PbO_(2)plate anodes have shown efficient mineralization of PFOA,it remains unclear whether PFOA can be effectively degraded usingβ-PbO_(2)reactive electrochemical membrane(REM).Herein,we assessed the performance of Ti/SnO_(2)-Sb/La-PbO_(2)REM for PFOA removal and proposed a possible degradation mechanism.At a current density of 10 mA/cm2and a membrane flux of 8500(liters per square meter per hour,LMH),the degradation efficiency of 10 mg/L PFOA was merely8.8%,whereas the degradation efficiency of 0.1 mg/L PFOA increased to 96.6%.Although the porous structure of theβ-PbO_(2)REM provided numerous electroactive sites for PFOA,the generated oxygen bubbles in the pores could block the pore channels and adsorb PFOA molecules.These hindered the protonation process and significantly impeded the degradation of high-concentration PFOA.Quenching experiments indicated that·OH played dominant role in PFOA degradation.The electrical energy per order to remove 0.1 mg/L PFOA was merely 0.74 Wh/L,which was almost an order of magnitude lower than that of other anode materials.This study presents fresh opportunities for the electrochemical degradation of low-concentration PFOA usingβ-PbO_(2)REM.展开更多
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...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.展开更多
Perfluorooctanoic acid(PFOA)is a widespread synthetic persistent organic pollutant that may enrich along the food chain and affect the growth,development,reproduction,and lipid metabolism of aquatic organisms,particul...Perfluorooctanoic acid(PFOA)is a widespread synthetic persistent organic pollutant that may enrich along the food chain and affect the growth,development,reproduction,and lipid metabolism of aquatic organisms,particularly the benthic organisms.How-ever,the toxic effects of PFOA on the half-smooth tongue sole Cynoglossus semilaevis,a commercial benthic fish in China,have rarely been reported.Because juvenile fish are sensitive to environmental pollutants,in the present study,histological assessment and tran-scriptome sequencing were performed to determine the short-term impact of PFOA on juvenile half-smooth tongue soles.Histologi-cal analysis showed that PFOA exposure caused hepatocyte rupture,intestinal villi breakage,increased goblet cell count,and brain ab-normal.Transcriptome results showed that some interesting signaling pathways,such as glycolysis/gluconeogenesis,PPAR signaling pathway and GABAergic synapse signaling pathway,were enriched after PFOA exposure.In addition,some metabolic,immune and neural genes were differentially expressed,which including ependymin,hbb1-like and gad 1,and they were up-regulated after 14 days of exposure.Transcriptome results also indicated that half-smooth tongue sole might improve energy metabolism in response to PFOA toxicity after 7 days of exposure.These findings provide a basis for studying the ecological effects of PFOA on marine benthic fishes.展开更多
Perfluorooctanoyl modified poly(vinyl alcohol)s (FPVA) were prepared by means of substituting a small amount of hydroxyl groups on the backbone of poly(vinyl alcohol), for which the initial degree of polymerization is...Perfluorooctanoyl modified poly(vinyl alcohol)s (FPVA) were prepared by means of substituting a small amount of hydroxyl groups on the backbone of poly(vinyl alcohol), for which the initial degree of polymerization is equal to 1750. The substitution extent, defined by the number of substituting units in a chain, for the four FPVA samples was in the range of 0.5-5 perfluorooctanoyl groups per chain. The FPVA samples with the highest substitution extent still had good solubility in water. It was shown by experimental measurement at 30.0 +/- 0.1 degreesC that the surface tension of the aqueous solution of the highest substituted FPVA decreased to 16.6 mN/m at a higher concentration, e.g. about 0.1 g/mL. Obviously, macromolecules of FPVA exhibit a very strong tendency to adsorb at the air-water interface, because the hydrophobic perfluorooctanoyl groups in FPVA have a very high surface activity as they are in small molecular fluorinated surfactants. The chain conformation of such a model polymer adsorbed on the air-water interface was also discussed.展开更多
In order to optimize the solid phase extraction(SPE)conditions of perfluorooctanoic acid(PFOA)in the raw leachate and treated leachate,the effects of activator properties,SPE cartridge,p H value,ionic strength,and elu...In order to optimize the solid phase extraction(SPE)conditions of perfluorooctanoic acid(PFOA)in the raw leachate and treated leachate,the effects of activator properties,SPE cartridge,p H value,ionic strength,and eluent properties were studied through single factor experiments.The optimal results of each single factor were obtained.Considering that the concentration of PFOA in the treated leachate is lower than that of the raw leachate,the SPE conditions of the treated leachate have been further optimized.Based on the above single-factor experiment,the main influencing factors were screened out as the volume of activator,ionic strength,and volume of eluent,and the three-factor threelevel response surface methodology(RSM)was optimized.The optimum SPE conditions of PFOA from treated landfill leachate were as follows:Activation of weak anion exchange(WAX)cartridge with 10 mL methanol,dosage of 600 mg KCl,6 m L 1%ammonia methanol eluted PFOA,the theory recovery rate is over95.67%.It has been verified that the error between the predicted value and the actual extraction recovery is small and has good repeatability.展开更多
The aggregation of multi-walled carbon nanotubes （MWCNTs） in the aqueous phase not only inhibits their extensive utilization in various aspects but also dominates their environmental fate and transport.The role of s...The aggregation of multi-walled carbon nanotubes （MWCNTs） in the aqueous phase not only inhibits their extensive utilization in various aspects but also dominates their environmental fate and transport.The role of surfactants at low concentration in the aggregation of MWCNTs has been studied,however the effect of perfluorinated surfactants at low concentration is uncertain.To understand this interfacial phenomenon,the influences of perfluorooctanoic acid （PFOA）,and sodium dodecyl sulfate （SDS） as a control,on MWCNT aggregation in the aqueous phase were examined by the UV absorbency method.Influences of pH and cationic species on the critical coagulation concentration （CCC） value were evaluated.The CCC values were dependent on the concentration of PFOA,however a pronounced effect of SDS concentration on the CCC values was not observed.The CCC values of the MWCNTs were 51.6 mmol/L in NaCl and 0.28 mmol/L in CaCl 2 solutions,which suggested pronounced differences in the effects of Na＋ and Ca2＋ ions on the aggregation of the MWCNTs.The presence of both PFOA and SDS significantly decreased the CCC values of the MWCNTs in NaCl solution.The aggregation of the MWCNTs took place under acidic conditions and was not notably altered under neutral and alkaline conditions due to the electrostatic repulsion of deprotonated functional groups on the surface of the MWCNTs.展开更多
文摘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.
文摘Fluorochemicals(FCs)are oxidatively recalcitrant,environmentally persistent,and resistant to most conventional treatment technologies.FCs have unique physiochemical properties derived from fluorine which is the most electronegative element.Perfluorooctanesulfonate(PFOS),and perfluorooctanoate(PFOA)have been detected globally in the hydrosphere,atmosphere and biosphere.Reducing treatment technologies such as reverses osmosis,nano-filtration and activated carbon can remove FCs from water.However,incineration of the concentrated waste is required for complete FC destruction.Recently,a number of alternative technologies for FC decomposition have been reported.The FC degradation technologies span a wide range of chemical processes including direct photolysis,photocatalytic oxidation,photochemical oxidation,photochemical reduction,thermally-induced reduction,and sonochemical pyrolysis.This paper reviews these FC degradation technologies in terms of kinetics,mechanism,energetic cost,and applicability.The optimal PFOS/PFOA treatment method is strongly dependent upon the FC concentration,background organic and metal concentration,and available degradation time.
基金supported by the National Natural Science Foundation of China(No.50808128).
文摘Perfluorooctanoic acid(PFOA),a novel contaminant,is extensively found in aquatic environments.However,the capability of the denitrifying phosphorus removal process to treat PFOA-containing wastewater,as well as its response mechanisms,are unclear.This study used batch experiments to assess the short-term impact of PFOA on denitrifying phosphorus removal systems.During a single cycle,the addition of PFOA predominantly enhanced phosphate removal in the system mainly by the anaerobic phosphorus release pathway,but had no substantial effect on nitrogen removal.COD removal efficiency has a substantial positive correlation with C6-HSL and C8-HSL concentrations.As the PFOA concentration increased,the ROS concentration and enzyme activity also increased,while the PN/PS ratio decreased,causing the sludge to become looser.At the beginning of the second cycle,the impact of PFOA on phosphorus removal efficiency shifted from promotion to inhibition.These findings shed fresh light on the influence of PFOA on the denitrifying phosphorus removal mechanism,potentially furthering its use in the treatment of fluoride-containing wastewater.
基金Project supported by the National Natural Science Foundation of China (No. 20577026) the New Century Excellent Talents in University (No. NCET-04-0090).
文摘The photodegradation of persistent and bioaccumulative perftuorooctanoic acid （PFOA） in water by 185 nm vacuum ultraviolet （VUV） light was examined to develop an effective technology to deal with PFOA pollution. PFOA degraded very slowly under irradiation of 254 nm UV light. However, 61.7% of initial PFOA was degraded by 185 nm VUV light within 2 h, and defluorination ratio reached 17.1%. Pseudo first-order-kinetics well simulated its degradation and defluorination. Besides, fluoride ion formed in water, 4 shorter-chain perfluorinated carboxylic acids （PFCAs）, that is, perfluoroheptanoic acid, perfluorohexanoic acid, perfluoropentanoic acid, and perfluorobutanoic acid. These were identified as intermediates by LC-MS measurement. These PFCAs consecutively formed and further degraded with irradiation time. According to the mass balance calculation, no other byproducts were formed. It was proposed that PFCAs initially are decarboxylated by 185 nm light, and the radical thus formed reacts with water to form shorter-chain PFCA with one less CF2 unit.
基金supported by the National Natural Science Foundation of China (Nos. 21607028, 41425015 and 41573086)the Research Grant Council of Hong Kong Special Administrative Region (SAR) Government (No. GRF14100115)+3 种基金Science and Technology Project of Guangdong Province, China (No. 2017A050506049)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (No. 2017BT01Z032)Innovation Team Project of Guangdong Provincial Department of Education (No. 2017KCXTD012)Leading Scientific, Technical and Innovation Talents of Guangdong Special Support Program (No. 2016TX03Z094)
文摘There is an urgent need for developing cost-effective methods for the treatment of perfluorooctanoic acid(PFOA)due to its global emergence and potential risks.In this study,taking surface-defective BiOCl as an example,a strategy of surface oxygen vacancy modulation was used to promote the photocatalytic defluorination efficiency of PFOA under simulated sunlight irradiation.The defective BiOCl was fabricated by a fast microwave solvothermal method,which was found to induce more surface oxygen vacancies than conventional solvothermal and precipitation methods.As a result,the asprepared BiOCl showed significantly enhanced defluorination efficiency,which was 2.7 and33.8 times higher than that of BiOCl fabricated by conventional solvothermal and precipitation methods,respectively.Mechanistic studies indicated that the defluorination of PFOA follows a direct hole(h^+)oxidation pathway with the aid of·OH,while the oxygen vacancies not only promote charge separation but also facilitate the intimate contact between the photocatalyst surface and PFOA by coordinating with its terminal carboxylate group in a bidentate or bridging mode.This work will provide a general strategy of oxygen vacancy modulation by microwave-assisted methods for efficient photocatalytic defluorination of PFOA in the environment using sunlight as the energy source.
基金supported by the National Natural Science Foundation of China (No. 20907026)the High Level Talent Research Foundation of Qindao Technological University (No:C-10-210)
文摘Perfluorooctanoic acid （PFOA） is a new-found hazardous persistent organic pollutant, and it is resistant to decomposition by hydroxyl radical （HO.） due to its stable chemical structure and the high electronegativity of fluorine. Photocatalytic reduction of PFOA with β-Ga2O3 in anoxic aqueous solution was investigated for the first time, and the results showed that the photoinduced electron （ecb） coming from the β-Ga2O3 conduction band was the major degradation substance for PFOA, and shorter-chain perfluorinated carboxylic acids （PFCAs, CnF2n＋1COOH, 1 ≤ n ≤ 6） were the dominant products. Furthermore, the concentration of F- was measured by the IC technique and defluorination efficiency was calculated. After 3 hr, the photocatalytic degradation efficiency was 98.8% and defluorination efficiency was 31.6% in the presence of thiosulfate and bubbling N2. The degradation reaction followed first-order kinetics （k = 0.0239 min-1, t1/2 = 0.48 hr）. PFCAs （CnF2n＋xCOOH, 1 ≤ n≤ 7） were detected and measured by LC-MS and LC-MS/MS methods. It was deduced that the probable photocatalytic degradation mechanism involves ec-b attacking the carboxyl of CnF2n＋1COOH, resulting in decarboxylation and the generation of CnFzn＋1. The produced CnF2n＋1 reacted with H2O, forming CnF2n＋1OH, then CnF2n＋1OH underwent HF loss and hydrolysis to form CnF2,＋1COOH.
基金financial support from Ministry of Science and Technology of the People’s Republic of China (Nos.2016YFE0112200 and 2016YFC0202700)National Natural Science Foundation of China (Nos.21507011,21677037 and 21607027)Natural Science Foundation of Shanghai (Nos. 19ZR1471200,17ZR1440200)
文摘Bismuth-based material has been broadly studied due to their potential applications in various areas,especially used as promising photocatalysts for the removal of persistent organic pollutants(POPs) and several approaches have been adopted to tailor their features.Herein,the bismuth-based photocatalysts(BiOCl,BiPO4,BiOPO4/BiOCl) were synthesized by hydrothermal method and advanced characterization techniques(XRD,SEM,EDS elemental mapping,Raman and UV-vis DRS) were employed to analyze their morphology,crystal structure,and purity of the prepared photocatalysts.These synthesized photocatalysts offered a praiseworthy activity as compared to commercial TiO2(P25) for the degradation of model pollutant perfluorooctanoic acid(PFOA) under 254 nm UV light.It was interesting to observe that all synthesized photocatalysts show significant degradation of PFOA and their photocatalytic activity follows the order:bismuth-based catalysts> TiO2(P25)> without catalyst.Bismuth-based catalysts degraded the PFOA by almost 99.99% within 45 min while this degradation efficiency was 66.05% with TiO2 under the same reaction condition.Our work shows that the bismuth-based photocatalysts are promising in PFOA treatment.
基金funding from Evoqua Companythe National Natural Science Foundation of China (Nos. 51878090 and 51808066)the Chinese Scholarship Council for financial support。
文摘When wood-based activated carbon was tailored with quaternary ammonium/epoxide(QAE) forming compounds(QAE-AC), this tailoring dramatically improved the carbon's effectiveness for removing perfluorooctanoic acid(PFOA) from groundwater. With favorable tailoring, QAE-AC removed PFOA from groundwater for 118,000 bed volumes before halfbreakthrough in rapid small scale column tests, while the influent PFOA concentration was 200 ng/L. The tailoring involved pre-dosing QAE at an array of proportions onto this carbon, and then monitoring bed life for PFOA removal. When pre-dosing with 1 mL QAE, this PFOA bed life reached an interim peak, whereas bed life was less following 3 mL QAE pre-dosing, then PFOA bed life exhibited a steady rise for yet subsequently higher QAE pre-dosing levels. Large-scale atomistic modelling was used herein to provide new insight into the mechanism of PFOA removal by QAE-AC. Based on experimental results and modelling, the authors perceived that the QAE's epoxide functionalities cross-linked with phenolics that were present along the activated carbon's graphene edge sites, in a manner that created mesopores within macroporous regions or created micropores within mesopores regions. Also, the QAE could react with hydroxyls outside of these pore, including the hydroxyls of both graphene edge sites and other QAE molecules. This latter reaction formed new pore-like structures that were external to the activated carbon grains. Adsorption of PFOA could occur via either charge balance between negatively charged PFOA with positively charged QAE, or by van der Waals forces between PFOA's fluoro-carbon tail and the graphene or QAE carbon surfaces.
基金funding provided by University at Albany,State University of New York。
文摘Nanophotocatalysts have shown great potential for degrading poly-and perfluorinated substances(PFAS).In light of the fact that most of these catalysts were studied in pure water,this study was designed to elucidate effects from common environmental factors on decomposing and defluorinating perfluorooctanoic acid(PFOA)by In2O3 nanoparticles.Results from this work demonstrated that among the seven parameters,pH,sulfate,chloride,H2O2,In2O3 dose,NOM and O2,the first four had statistically significant negative effects on PFOA degradation.Since PFOA is a strong acid,the best condition leading to the highest PFOA removal was identified for two pH ranges.When pH was between 4 and 8,the optimal condition was:pH=4.2;sulfate=5.00 mg/L;chloride=20.43 mg/L;H2O2=0 mmol/L.Under this condition,PFOA decomposition and defluorination were 55.22 and 23.56%,respectively.When pH was between 2 and 6,the optimal condition was:pH=2;sulfate=5.00 mg/L;chloride=27.31 mg/L;H2O2=0 mmol/L.With this condition,the modeled PFOA decomposition was 97.59%with a defluorination of approximately 100%.These predicted results were all confirmed by experimental data.Thus,In2O3 nanoparticles can be used for degrading PFOA in aqueous solutions.This approach works best when the target contaminated water contains low concentrations of NOM,sulfate and chloride and at a low pH.
基金supported by the National Natural Science Foundation of China (No.21625702)。
文摘Perfluorooctanoic acid(PFOA), its salts, and related compounds were listed as new persistent organic pollutants by the Stockholm Convention in 2019.In this study, the occurrence of residues of PFOA and other per-and polyfluoroalkyl substances(PFASs) in raw materials and fluoropolymer products from the Chinese fluoropolymer industries are reported for the first time.The PFOA concentrations in raw materials and fluoropolymer products were in the range of 6.7 to 1.1 × 10^(6) ng/g, and <MDL(method detection limit) to 5.3 × 10^(3) ng/g,respectively.Generally, the levels of PFOA in raw materials were higher than in products,implying that PFOA in the emulsion/dispersion resin could be partly removed during the polymerization or post-processing steps.By tracking a company’s polytetrafluoroethylene(PTFE) production line, it was found that over a 5 year period, the residual levels of PFOA in emulsion samples declined from 1.1 × 10^(6) to 28.4 ng/g, indicating that the contamination of PFOA in fluoropolymer products from production source gradually decreased after its use had been discontinued.High concentrations of HFPO-TrA(2.7 × 10^(5) to 8.2 × 10^(5) ng/g) were detected in some emulsion samples indicating this alternative has been widely applied in fluoropolymer manufacturing in China.
文摘Environmentally persistent and bioaccumulative perfluorooctanic acid （PFOA） was difficult to be decomposed under the irradiation of 254 nm UV light. However, in the presence of 80μmol/L Fe（Ⅲ）, 80% of PFOA with initial concentration of 48μmol/L （20 mg/L） was effectively degraded and 47.8% of fluorine atoms in PFOA molecule were transformed into inorganic fluoride ion after 4 h reaction. Shorter chain perfluorocarboxylic acids bearing C3-C7 and fluoride ion were detected and identified by LC/MS and IC as the degradation products in the aqueous solution. It was proposed that complexes of PFOA with Fe（Ⅲ） initiated degradation of PFOA irradiated with 254 nm UV light.
基金supported by the National Basic Research Program(973)of China(No.2010CB933600)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA09030203)+4 种基金the National Natural Science Foundation of China(Nos.2127716141103076)the special fund from the State Key Laboratory of Environmental Aquatic Chemistry(No.10Y10ESPCR)the Youth Innovation Promotion AssociationChinese Academy of Sciences(29QNCX2012005)
文摘Perfluorooctanoic acid（PFOA）is recalcitrant to degrade and mineralize.Here,the effect of temperature on the photolytic decomposition of PFOA was investigated.The decomposition of PFOA was enhanced from 34% to 99% in 60 min of exposure when the temperature was increased from 25 to 85℃ under UV light（201–600 nm）.The limited degree of decomposition at 25℃ was due to low quantum yield,which was increased by a factor of 12 at 85℃.Under the imposed conditions,the defluorination ratio increased from 8% at 25℃ to 50% at85℃ in 60 min.Production of perfluorinated carboxylic acids（PFCAs,C7–C5）,PFCAs（C4–C3）and TFA（trifluoroacetic acid,C2）accelerated and attained a maximum within 30 to 90 min at 85℃.However,these reactions did not occur at 25℃ despite extended irradiation to180 min.PFOA was decomposed in a step-wise process by surrendering one CF2unit.In each cyclical process,increased temperature enhanced the quantum yields of irradiation and reactions between water molecules and intermediates radicals.The energy consumption for removing eachμmol of PFOA was reduced from 82.5 k J at 25℃ to 10.9 k J at 85℃ using photolysis.Photolysis coupled with heat achieved high rates of PFOA degradation and defluorination.
基金supported by the National Natural Science Foundation of China(Nos.21878323,21736001)National Key R&D Program of China(No.2020YFC1807901)Talent program(No.2021RC022)。
文摘Nanofiltration(NF)process has become one of the most promising technologies to remove micro-organic combined water pollution.Developing a NF membrane material with efficient separation for perfluorooctanoic acid(PFOA)combined pollution is highly desired,this manuscript targets this unmet need specifically.In this work,hydrophilic SiO_(2)nanoparticles with various contents blended with carboxylic multiwalled carbon nanotube were used to modify poly(m-phenylene isophthal amide)(SiO_(2)/CMWCNT/PMIA)hollow fiber NF membrane.The modified membrane with 0.1 wt%SiO_(2)doping exhibits way better fouling resistance with irreversible fouling ratio decreased dramatically from 18.7%to 2.3%,and the recovery rate of water flux increases significantly from 81.2%to 97.7%.The separation experiment results had confirmed that the modified membrane could improve the rejection from 97.2%to 98.6%for perfluorooctanoic acid(PFOA)and its combined pollution with bovine serum albumin(BSA).It is clear that this reported SiO_(2)/CMWCNT/PMIA hollow fiber NF membrane potentially could be applied in water treatment.This research also provides a theoretical basis for efficiently removal of PFOA and its combined pollution by NF membrane.
基金financially supported by the National Key Research and Development Program(No.2022YFE0135700)the National Natural Science Foundation of China(Nos.52000028,52370076 and 51978658)+1 种基金the Fundamental Research Funds for the Central Universities(No.2023MS063)Australian Research Council(No.G180200015)。
文摘Aqueous perfluorooctanoic acid(PFOA)elimination has raised significant concerns due to its persistence and bioaccumulation.Althoughβ-PbO_(2)plate anodes have shown efficient mineralization of PFOA,it remains unclear whether PFOA can be effectively degraded usingβ-PbO_(2)reactive electrochemical membrane(REM).Herein,we assessed the performance of Ti/SnO_(2)-Sb/La-PbO_(2)REM for PFOA removal and proposed a possible degradation mechanism.At a current density of 10 mA/cm2and a membrane flux of 8500(liters per square meter per hour,LMH),the degradation efficiency of 10 mg/L PFOA was merely8.8%,whereas the degradation efficiency of 0.1 mg/L PFOA increased to 96.6%.Although the porous structure of theβ-PbO_(2)REM provided numerous electroactive sites for PFOA,the generated oxygen bubbles in the pores could block the pore channels and adsorb PFOA molecules.These hindered the protonation process and significantly impeded the degradation of high-concentration PFOA.Quenching experiments indicated that·OH played dominant role in PFOA degradation.The electrical energy per order to remove 0.1 mg/L PFOA was merely 0.74 Wh/L,which was almost an order of magnitude lower than that of other anode materials.This study presents fresh opportunities for the electrochemical degradation of low-concentration PFOA usingβ-PbO_(2)REM.
基金support from the Brook Byers Institute for Sustainable Systems,Hightower Chair,and Georgia Research Alliance at the Georgia Institute of Technology.
文摘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.
基金supported by the National Key R&D Program(No.2018YFD0900301-03)the MNR Key Laboratory of Marine Eco-Environmental Science and Technology,China(No.MEEST-2021-04).
文摘Perfluorooctanoic acid(PFOA)is a widespread synthetic persistent organic pollutant that may enrich along the food chain and affect the growth,development,reproduction,and lipid metabolism of aquatic organisms,particularly the benthic organisms.How-ever,the toxic effects of PFOA on the half-smooth tongue sole Cynoglossus semilaevis,a commercial benthic fish in China,have rarely been reported.Because juvenile fish are sensitive to environmental pollutants,in the present study,histological assessment and tran-scriptome sequencing were performed to determine the short-term impact of PFOA on juvenile half-smooth tongue soles.Histologi-cal analysis showed that PFOA exposure caused hepatocyte rupture,intestinal villi breakage,increased goblet cell count,and brain ab-normal.Transcriptome results showed that some interesting signaling pathways,such as glycolysis/gluconeogenesis,PPAR signaling pathway and GABAergic synapse signaling pathway,were enriched after PFOA exposure.In addition,some metabolic,immune and neural genes were differentially expressed,which including ependymin,hbb1-like and gad 1,and they were up-regulated after 14 days of exposure.Transcriptome results also indicated that half-smooth tongue sole might improve energy metabolism in response to PFOA toxicity after 7 days of exposure.These findings provide a basis for studying the ecological effects of PFOA on marine benthic fishes.
基金The project was supported by the National Natural Science Foundation of China (No.29774016).
文摘Perfluorooctanoyl modified poly(vinyl alcohol)s (FPVA) were prepared by means of substituting a small amount of hydroxyl groups on the backbone of poly(vinyl alcohol), for which the initial degree of polymerization is equal to 1750. The substitution extent, defined by the number of substituting units in a chain, for the four FPVA samples was in the range of 0.5-5 perfluorooctanoyl groups per chain. The FPVA samples with the highest substitution extent still had good solubility in water. It was shown by experimental measurement at 30.0 +/- 0.1 degreesC that the surface tension of the aqueous solution of the highest substituted FPVA decreased to 16.6 mN/m at a higher concentration, e.g. about 0.1 g/mL. Obviously, macromolecules of FPVA exhibit a very strong tendency to adsorb at the air-water interface, because the hydrophobic perfluorooctanoyl groups in FPVA have a very high surface activity as they are in small molecular fluorinated surfactants. The chain conformation of such a model polymer adsorbed on the air-water interface was also discussed.
基金Supported by the Grant from the Science and Technique Key Programs of Power China Ltd.(P45220)the Open-ended Fund of Chongqing University’s Large-Scale Equipment(202203150184)
文摘In order to optimize the solid phase extraction(SPE)conditions of perfluorooctanoic acid(PFOA)in the raw leachate and treated leachate,the effects of activator properties,SPE cartridge,p H value,ionic strength,and eluent properties were studied through single factor experiments.The optimal results of each single factor were obtained.Considering that the concentration of PFOA in the treated leachate is lower than that of the raw leachate,the SPE conditions of the treated leachate have been further optimized.Based on the above single-factor experiment,the main influencing factors were screened out as the volume of activator,ionic strength,and volume of eluent,and the three-factor threelevel response surface methodology(RSM)was optimized.The optimum SPE conditions of PFOA from treated landfill leachate were as follows:Activation of weak anion exchange(WAX)cartridge with 10 mL methanol,dosage of 600 mg KCl,6 m L 1%ammonia methanol eluted PFOA,the theory recovery rate is over95.67%.It has been verified that the error between the predicted value and the actual extraction recovery is small and has good repeatability.
基金supported by the National Natural Science Foundation of China(No.20977043,20777033)the Opening Funding of State Key Laboratory of Pollution Control and Resource Reuse(No.PCRRF12012)
文摘The aggregation of multi-walled carbon nanotubes （MWCNTs） in the aqueous phase not only inhibits their extensive utilization in various aspects but also dominates their environmental fate and transport.The role of surfactants at low concentration in the aggregation of MWCNTs has been studied,however the effect of perfluorinated surfactants at low concentration is uncertain.To understand this interfacial phenomenon,the influences of perfluorooctanoic acid （PFOA）,and sodium dodecyl sulfate （SDS） as a control,on MWCNT aggregation in the aqueous phase were examined by the UV absorbency method.Influences of pH and cationic species on the critical coagulation concentration （CCC） value were evaluated.The CCC values were dependent on the concentration of PFOA,however a pronounced effect of SDS concentration on the CCC values was not observed.The CCC values of the MWCNTs were 51.6 mmol/L in NaCl and 0.28 mmol/L in CaCl 2 solutions,which suggested pronounced differences in the effects of Na＋ and Ca2＋ ions on the aggregation of the MWCNTs.The presence of both PFOA and SDS significantly decreased the CCC values of the MWCNTs in NaCl solution.The aggregation of the MWCNTs took place under acidic conditions and was not notably altered under neutral and alkaline conditions due to the electrostatic repulsion of deprotonated functional groups on the surface of the MWCNTs.
