Synthesis and Properties of Perfluorinated Alkyl Silicone Oil Modified Epoxy Resin

Perfluorinated alkyl silicone oil （PFASO） was successfully synthesized from N-ethyl-N- hydroxylethyl perfluorinated octane sulfonamide, succinie anhydride and amino silicone oil by esterification and amide reaction at moderate temperature in the presence of different catalysts. The chemical structure of the synthesized samples was characterized by Fourier transform infrared spectroscopy （FT-IR）, the relative molecular mass（MM） and molecular mass distribution（MMD） of PFASO were tested by gel filtration chromatography（GFC）. A commercial epoxy resin （DGEBA） was modified with PFASO, with the content of PFASO 1-5 phr. Thermo-gravimetric analysis （TGA）, impact tests, scanning electron microscope （SEM） and water contact angle test were applied to provide accurate results on the thermal stability, toughness and hydrophobicity of PFASO/epoxy complex. The experimental results reveal that epoxy resins can be successfully modified by adding a small amount of as-synthesized modifiers via simple direct mixing, and verify that the as-synthesized modifier can improve the toughness and hydrophobicity of epoxy resin without sacrificing its thermal properties.

Assessment of Heavy Metals,Polycyclic Aromatic Hydrocarbons,and Perfluorinated Alkyl Substances in two Marine Crustaceans(Oratosquilla oratoria and Portunus trituberculatus)in the Zhoushan Fishing Ground of China East Sea

Heavy metals,polycyclic aromatic hydrocarbons(PAHs),and perfluorinated alkyl substances(PFASs)polluted in 155 samples of two marine crustaceans(Oratosquilla oratoria and Portunus trituberculatus)harvested in the Zhoushan fishing ground in the East China Sea were assessed.The results showed that Pb,Hg,and iAs in the whole edible parts of O.oratoria and P.trituberculatus were at trace levels,far below the limits set by the China’s national standard,whereas the exceeding standard rates of Cd in the whole edible parts of O.oratoria and P.trituberculatus were 98.6%and 75.6%,respectively.Moreover,the average Cd levels and the exceeding standard rates of Cd in the visceral tissues of O.oratoria were significantly higher than those in the muscle tissues(4.64 mg kg^(−1)vs.0.49 mg kg^(−1)and 96.7%vs 30%,respectively).PAHs with high detection frequency in the two marine crustaceans included NA,AC,FL,and PHE.Total contents of 15 PAHs(abbreviated asΣ15 PAHs)in whole edible parts of O.oratoria and P.trituberculatus were 10.75–65.9μg kg^(−1)(mean=18.7μg kg^(−1)and 13.26–181μg kg^(−1)(mean=24.2μg kg^(−1),and those in the muscle and the visceral tissues of P.trituberculatus were 9.58–160μg kg^(−1)(mean=21.1μg kg^(−1)and 18.22–201μg kg^(−1)(mean=32.7μg kg^(−1),respectively.Furthermore,PFASs that were found at high contents included PFOA,PFOS,and PFOSA,and total contents of 23 PFASs(Σ23 PFASs)ranged 0.0162–5.104μg kg^(−1)(mean=0.915μg kg^(−1).Collectively,the present work provides new data on the contamination in two marine crustaceans captured in the Zhoushan fishing ground in the China East Sea,which can be useful for making suggestions on proper consumption amounts of the two marine crustaceans.

Elimination of matrix effects during analysis of perfluorinated acids in solid samples by liquid chromatography tandem mass spectrometry

Matrix effects can significantly hamper the accuracy and precision of the analysis results of perfluorinated acids （PFAs） in environmental solid samples. Several methods, such as standard addition, isotopically labeled internal standards, clean-up of SPE （solid phase extraction） eluents by dispersive graphitized carbon sorbent and substitution of eletrospray ionization （ESI） source by atmosphere pressure photoionization （APPI） source, were demonstrated for elimination of matrix effects in quantitative analysis of PFAs in solid samples. The resuRs indicate that matrix effects can be effectively eliminated by standard addition, but instrumental analysis time will be multiplied. Isotopically labeled internal standards can effectively negate matrix effects of PFAs with the same perfluorocarbon chain length, but is not valid for the other analytes. Although APPI can eliminate matrix effects for all analytes, it is only suitable for analysis of high pollution levels samples. Clean-up of SPE eluents by dispersive graphitized carbon sorbent not only effectively negate the impact of matrix effect, but also avoid frequent clean of the ESI in order to maintain instrumental sensitivity. Therefore, the best method for elimination of matrix effects is the usage of dispersive graphitized carbon sorbent for clean-up of SPE elution.

Synthesis and Characterization of 2-cetyl-3-20 keto acid(N-ethyl perfluorinated octyl sulfonamide) N-ethyl ester

2-Cetyl-3-20 keto acid（N-ethyl perfluorinated octyl sulfonamide） N-ethyl ester was synthesized by the reaction of N-ethyl-N-hydroxyethyl perfluorinated octyl sulfonamide and alky ketene dimer. The experimental results show that the yield of products can be 89% when the molar ratio of perfluorinated octyl sulfonamide to ketene dimer is 1 ： 1.1 and the reaction lasts about four hours at 80 ℃. The structure of the product was characterized by FTIR and ^1HNMR. The product can dissolve in polar solvents such as NMP, DMAC, THF, DMSO, CHCl3, and 10% weight-loss temperature measured by TGA is 202℃.

Quantification of perfluorinated compounds in atmospheric particulate shows potential connection with environmental event

A method of quantification of perfluorinated compounds(PFCs)from atmospheric particulate matter(APM)is described.A single step pretreatment method,selective pressurized liquid extraction(SPLE),was developed to reduce the high matrix background and avoid contamination from commonly used multiple sample pretreatment steps.An effective sorbent was selected to purify the PFCs during SPLE,followed by liquid chromatography-tandem mass spectrometry(LC–MS/MS),for quantification of PFCs.Conditions affecting the SPLE efficiency,including temperature,static extraction time,and number of extraction cycles used,were studied.The optimum conditions were found to be 120℃,10 min,and 3 cycles,respectively.LC-MS/MS method was developed to obtain the optimal sensitivity specific to PFCs.The method detection limits(MDLs)were 0.006 to 0.48 ng/g for the PFCs studied and the linear response range was from 0.1 to 100 ng/g.To ensure accurate values were obtained,each step of the experiment was evaluated and controlled to prevent contamination.The optimized method was tested by performing spiking experiments in natural particulate matter matrices and good rates of recovery and reproducibility were obtained for all target compounds.Finally,the method was successfully used to measure 16 PFCs in the APM samples collected in Beijing over five years from 2015 to 2019.It is observed that some PFCs follow the trend of total PFC changes,and can be attributed to the environment influencing events and policy enforcement,while others don't seem to change as much with time of the year or from year to year.

Evaluation of perfluorinated compounds in seven wastewater treatment plants in Beijing urban areas

The presence of perfluorinated compounds(PFCs)in seven major wastewater treatment plants(WWTPs)in Beijing was investigated in the current study.We detected nine PFCs in all the wastewater and sludge samples.Perfluorooctane acid(PFOA)is the dominant PFCs in influents and effluents,while perfluorooctane sulfonate(PFOS)is the major contaminant in sludge.The highest PFC concentration was found in plants at Qinghe and Jiuxianqiao WWTP,while the lowest was found at Fangzhuang WWTP.The total values of PFC range from 2.88 to 176 ng/L in influents,from 5.48 to 498 ng/L in effluents,and from 1.21 to 32.0 ng/g(dry wt)in sludge.The fact that effluents usually contain higher levels of PFCs than influents suggests that additional PFCs are produced during the wastewater treatment processes.However,PFOS decreases in effluents than in influents in 62%of the water samples.This may be due to the adsorption and removal of the sludge during the active process.Perfluoroalkyl carboxylates(PFCAs)were found significantly correlated with each other in the effluents,which may indicate their similar sources or the existence of their potential precursors in the wastewater or treatment processes.The mass flows of PFC discharges into WWTPs are 0.4–51.4 mg/day,and the mass flows of PFCs in effluents exceed those in influents by 127%.Domestic and commercial wastewaters are suggested to be the major sources of PFC pollution in WWTPs in Beijing.

Electrolytes enriched by potassium perfluorinated sulfonates for lithium metal batteries

Lithium(Li) metal is widely considered as a promising anode for next-generation lithium metal batteries(LMBs) due to its high theoretical capacity and lowest electrochemical potential. However, the uncontrollable formation of Li dendrites has prevented its practical application. Herein, we propose a kind of multifunctional electrolyte additives(potassium perfluorinated sulfonates) from the multi-factor principle for electrolyte additive molecular design(EDMD) view to suppress the Li dendrite growth. The effects of these additives are revealed through experimental results, molecular dynamics simulations and firstprinciples calculations. Firstly, K^(+)can form an electrostatic shield on the surface of Li anode to prevent the growth of Li dendrites. Secondly, potassium perfluorinated sulfonates can improve the activity of electrolytes as co-conductive salts, and lower the electro-potential of Li nucleation. Thirdly, perfluorinated sulfonate anions not only can change the Li^(+)solvation sheath structure to decrease the desolvation energy barrier and increase the ion migration rate, but also can be partly decomposed to form the superior solid electrolyte interphase(SEI). Benefited from the synergistic effects, an outstanding cycle life over250 h at 1 m A cm^(-2) is achieved in symmetric Li||Li cells. In particular, potassium perfluorinated sulfonate additives(e.g., potassium perfluorohexyl sulfonate, denoted as K+PFHS) can also contribute to the formation of high-quality cathode electrolyte interphase(CEI). As a result, Li||LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2) full cells exhibit significantly enhanced cycling stability. This multi-factor principle for EDMD offers a unique insight on understanding the electrochemical behavior of ion-type electrolyte additives on both the Li metal anode and high-voltage cathode.

The short-chain perfluorinated compounds PFBS,PFHxS, PFBA and PFHxA, disrupt human mesenchymal stem cell self-renewal and adipogenic differentiation

Per-and polyfluorinated alkyl substances(PFASs) are commonly used in industrial processes and daily life products.Because they are persistent, they accumulate in the environment, wildlife and humans.Although many studies have focused on two of the most representative PFASs, PFOS and PFOA, the potential toxicity of short-chain PFASs has not yet been given sufficient attention.We used a battery of assays to evaluate the toxicity of several four-carbon and six-carbon perfluorinated sulfonates and carboxyl acids(PFBS,PFHxS, PFBA and PFHxA), with a human mesenchymal stem cell(hMSC) system.Our results demonstrate significant cyto-and potential developmental toxicity for all the compounds analyzed, with shared but also distinct mechanisms of toxicity.Moreover, the effects of PFBS and PFHxS were stronger than those of PFBA and PFHxA, but occurred at higher doses compared to PFOS or PFOA.

Perfluorinated compounds in blood of textile workers and barbers

12 perfluorinated compounds（PFCs） in human blood from workers in a textile mill in Shandong province and several barbershops in Tianjin were analyzed in this study. It was found that perfluorooctanesulfonate（PFOS） and perfluorooctanoate（PFOA） were the most prominent PFCs, with average concentrations of 5.73 mg/L and 5.46 mg/L for textile workers, and 2.55 mg/L and 2.84 mg/L for barbers.PFOS and perfluorohexanesulfonate（PFHxS） concentrations revealed a positive correlation in blood samples（p 〈 0.01）, and concentrations among PFOS, perfluorononanoic acid（PFNA） and perfluorodecanoic acid（PFDA） also revealed positive correlations（p 〈 0.01）. The influence of gender and age on PFC concentration in blood was also investigated, and the results showed that there was no statistically significant difference between the male and female samples, as well as in samples from people with different ages. Generally speaking, the textile workers

Effect of co-existing organic compounds on adsorption of perfluorinated compounds onto carbon nanotubes

Co-existing organic compounds may affect the adsorption of perfluorinated compounds （PFCs） and carbon nanotubes in aquatic environments. Adsorption of perfluorooctane sulfonate （PFOS）, perfluorooctane acid （PFOA）, perfluorobutane sulfonate （PFBS）, and perfluor- ohexane sulfonate （PFHxS） on the pristine multi-walled carbon nanotubes （MWCNTs-Pri）, carboxyl functionalized MWCNTs （MWCTNs-COOH）, and hydroxyl functiona- lized MWCNTs （MWCNTs-OH） in the presence of humic acid, 1-naphthol, phenol, and benzoic acid was studied. Adsorption kinetics of PFOS was described well by the pseudo-second-order model and the sorption equilibrium was almost reached within 24 h. The effect of co-existing organic compounds on PFOS adsorption followed the decreasing order of humic acid 〉 1-naphthol 〉 benzoic acid〉phenol. Adsorbed amounts of PFOS decreased significantly in the presence of co-existing or preloaded humic acid, and both adsorption energy and effective adsorption sites on the three MWCNTs decreased, resulting in the decrease of PFOS adsorption. With increasing pH, PFOS removal by three MWCNTs decreased in the presence of humic acid and phenol. The adsorbed amounts of different PFCs on the MWCNTs increased in the order ofPFBS 〈 PFHxS 〈 PFOA 〈 PFOS. The increase of both initial concentrations and the number of aromatic rings of co-existing organic compounds suppressed PFOS adsorption on the MWCNTs.

Recent advances in electrochemical decontamination of perfluorinated compounds from water: a review

Per- and polyfluoroalkyl substances (PFAS) pose serious human health and environmental risks due to their persistence and toxicity. Among the available PFAS remediation options, the electrochemical approach is promising with better control. In this review, recent advances in the decontamination of PFAS from water using several state-of-the-art electrochemical strategies, including electro-oxidation, electro-adsorption, and electro-coagulation, were systematically reviewed. We aimed to elucidate their design principles, underlying working mechanisms, and the effects of operation factors (e.g., solution pH, applied voltage, and reactor configuration). The recent developments of innovative electrochemical systems and novel electrode materials were highlighted. In addition, the development of coupled processes that could overcome the shortcomings of low efficiency and high energy consumption of conventional electrochemical systems was also emphasized. This review identified several major knowledge gaps and challenges in the scalability and adaptability of efficient electrochemical systems for PFAS remediation. Materials science and system design developments are forging a path toward sustainable treatment of PFAS-contaminated water through electrochemical technologies.

Detection of the Destruction Mechanism of Perfluorinated Elastomer(FFKM)Network under Thermo-oxidative Aging Conditions

The changes of crosslinking network of perfluorinated elastomer(FFKM)cured by TAIC and DBPH under thermo-oxidative aging conditions were investigated.Two competitive processes including post-curing and network destruction occur simultaneously,which directly affect the storage modulus and crosslinking density.With the increase of aging temperature,the network destruction becomes dominant.FTIR and XPS characterizations further reveal that the network destruction happens preferentially on the crosslink points of TAIC structure,and the post-curing is mainly caused by the decomposition of residual curing agent DBPH.Unlike the easier breaking of TAIC structure in the crosslinking network,both the backbone and the pendent groups of FFKM itself are much more stable.To further figure out the destruction mechanism,TGAFTIR-GC-MS test was also conducted and a schematic degradation process of TAIC structure was proposed.It is found that the destruction of TAIC crosslinking points happens first on the unstable exocyclic C―N bonds and the intermediate ring radicals could eventually decompose into volatile hydrogen isocyanate(HCNO)under extreme condition.

Process simulation and economic analysis of reactor systems for perfluorinated compounds abatement without HF effluent

New and efficient proposed to treat perfluorinated reactor systems were compounds via catalytic decomposition. One system has a single reactor （S-1）, and another has a series of reactors （S-2）. Both systems are capable of producing a valuable CaF2 and eliminating toxic HF effluent and their feasibility was studied at various temperatures with a commercial process simulator, Aspen HYSYS. They are better than the conventional system, and S-2 is better than S-1 in terms of CaF2 production, a required heat for the system, natural gas usage and CO2 emissions in a boiler, and energy consumption. Based on process simulation results, preliminary economic analysis shows that cost savings of 12.37% and 13.55% were obtained in S-2 at 589.6 and 621.4℃compared to S-1 at 700 and 750 ℃, respectively, for the same amount of CaF2 production.

Occurrence of pharmaceuticals and perfluorinated compounds and evaluation of the availability of reclaimed water in Kinmen

Emerging contaminants have commonly been observed in environmental waters but have not been included in water quality assessments at many locations around the world.To evaluate the availability of reclaimed water in Kinmen,Taiwan,this study provides the first survey of the distribution of thirty-three pharmaceuticals and five perfluorinated chemicals in lake waters and water from local wastewater treatment plants(WWTPs).The results showed that the target emerging contaminants in Kinmen lakes were at trace ng/L concentrations.In addition,most of the target compounds were present in the Jincheng and Taihu WWTP influents at ng/L concentrations levels,of which 5 compounds(erythromycin-H2O(1340 ng/L),ibuprofen(1763 ng/L),atenolol(1634 ng/L),acetaminophen(2143 ng/L),and caffeine(3113 ng/L))reached mg/L concentrations.The overall treatment efficiencies of the Jincheng and Taihu WWTPs with respect to these pharmaceuticals and perfluorinated chemicals were poor;half of the compounds were less than 50%removed.Five compounds(sulfamethoxazole,erythromycin-H2O,clarithromycin,ciprofloxacin and ofloxacin)with risk quotient(RQ)values>1 in the effluent should be further investigated to understand their effects on the aquatic environment.Additional and advanced treatment units are found necessary to provide high-quality recycled water and sustainable water resources.

Synthesis and Characterization of a Novel Perfluorinated Ionomer Polymer Containing Sulfonimide Functionality

The novel perfluorinated vinyl ether containing sulfonimide functionality CF2 = CFORfSO2NHSO2CF3 was synthesized by multiple reaction steps. It could be copolymerized with tetraflu-oroethylene by radox initiator to give a novel perfluorinated ionomer polymer. Its physical and chemical properties were studied.

Synthesis of a Novel Perfluorinated Vinyl Ether Containing Sulfonimide and Phosphonic Acid Functionalities

The novel perfluorinated vinyl ether containing sulfonimide and phosphonic acid functionalities, CF2 = CFOCF2CF(CF3)-OCF2CF2SO2NHSO2(CF2)2P(O)(OH)2, has been synthesized by multiple reaction steps. It is a very strong bi-functional acid and exhibits a high degree of stability in aqueous solution at an elevated temperature. These properties make it an attractive monomer for the preparation of the co-polymer with TFE to obtain the high quality ionomer membrane and proton conductor.

Photodegradation of perfluorooctanoic acid by 185 nm vacuum ultraviolet light

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.

Estimation of Reference Values for PFOS and PFOA in Human Biomonitoring and Relevance of Exposure among Family Members in China

The reference values of serum perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) concentrations were evaluated based on the human blood samples collected from Kashi, Xinjiang. And human serum samples of family members from Liaoning were evaluated for levels of PFOS and PFOA with the purpose to compare exposure pathways for family members. Among the 110 blood specimens from Kashi, the detection frequency of PFOS and PFOA was 93% and 6%, respectively. Reference values of serum PFOS, evaluated as the 90th percentiles of the concentrations, were determined to be 6.44 μg/L. Significant positive correlations were observed for serum levels of PFOS and PFOA among family members in Liaoning. Specially, stronger correlation between mother and offspring was observed than that between father and offspring. And stronger correlation of serum PFOS and PFOA levels was observed among fam- ily members in rural areas than those in big and small-medium cities. Difference in the association of serum PFOS and PFOA level among family members suggested that exposure in the outdoor and working environment of different oc- cupations should be evaluated. Present study provides reference values for exposure assessment in China and potential pathways of human exposure to PFOS and PFOA.

Synthesis of the Novel Fluoride-containing Organic Silane

A fluoride-containing organic silane was synthesized by the reaction of N-ethyl- N-hydroxy-etbyl perfluorinated octyl sulfonamide （EHPOS）, N-（β-aminoethyl）-γ-aminopropyl trimethoxy silane （ATS） and cis-butenedioic anhydride （CA）. The experimental results show that the yield of product is up to 87% when the molar ratio ofEHPOS ： CA ： ATS is 1 ： 1.05 ： 1.1. EHPOS and CA were maintained at 115 ℃ for 3 hours, then after cooling the reaction solution to 75 ℃, ATS was added and reacted for another 3.5 hours at 145 ℃. The structure of the product and thermal properties were characterized by Fourier transform infrared （FTIR） and thermogravimetric analysis （TGA）, respectively. Results show that fluoride-containing organic silane has excellent thermal stability below 185℃.

Transport Properties of Novel Hybrid Cation-Exchange Membranes on the Base of MF-4SC and Halloysite Nanotubes

The diffusion permeability through new hybrid materials based on a Nafion-type membrane (MF- 4SC) and nanotubes of halloysite is investigated using the Nernst-Planck approach. A method of quantitative evaluation of physicochemical parameters (averaged and individual diffusion coefficients and averaged distribution coefficients of ion pairs in the membrane) of system “electrolyte solution—ion-exchange membrane—water”, which was proposed earlier, is further developed. The parameters of hybrid membranes on the base of MF-4SC and nanotubes of halloysite (5% wt and 8% wt) are obtained from experimental data on diffusion permeability of NaCl solutions using theoretical calculations. New model of three-layer membrane system can be used for refining calculated results with taking into account both diffusive layers. It is shown that adding of halloysite nanotubes into the membrane volume noticeably affects exchange capacity as well as structural and transport characteristics of original perfluorinated membranes. Hybrid membranes on the base of MF-4SC and halloysite nanotubes can be used in fuel cells and catalysis.