Perfluorooctanoic Acids Research Articles

Removal mechanism and effects of aqueous chemistry on rapid adsorption of perfluorooctanoic and perfluorooctanesulfonic acids by microscale zero valent magnesium

Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) as the two most typical perfluorinated compounds, their effective and rapid removal are still facing enormous challenges. In this study, the adsorption performance and mechanism of PFOA and PFOS by ball milled micrometer zero valent magnesium (mZVMg) were revealed firstly through the adsorption kinetics and isothermal, ions coexisting competitive adsorption and extraction experiments. Rapid adsorption equilibrium within 0.5 h was observed in the mZVMg system, and the higher adsorption affinities at 1.9 and 6.5 L/mg for PFOA and PFOS respectively were approximately 4.4–110 times higher than those of the carbon materials, layered double hydroxide and magnetite reported in the literature. Correspondingly, high removal efficiencies for PFOS were observed even under a wide pH ranging from 3.0 to 11.0. In the meantime, negligible influences on the PFOS adsorption were identified from the coexisting PFOA, perfluorobutanoic acid (PFBA), perfluorobutanoic sulfonic acid (PFBS), anions of Cl−, NO3− and SO42−. Reversely, the PFOA adsorption was adversely influenced by enhanced electrostatic repulsion under the increased pH and the presence of the abovementioned anions. Additionally, the original removal efficiency of 67.18 % for PFOA in the absence of any cations and anions was decreased to 7.98 %, 31.08 % and 39.65 % respectively in the presence of humic acid, HCO3− and CO32−. Similarly, the removal efficiency of 94.41 % for PFOS was declined to 40.01 %, 70.04 % and 80.58 % respectively when humic acid, HCO3− and CO32− were added to the solution. However, in the presence of respective Mg2+ and Ca2+, the original removal efficiencies were increased from 67.18 % to 75.78 % and 74.68 % for PFOA, and from 84.99 % to 93.23 % and 92.49 % for PFOS, likely due to the cation’s bridge effect. Consequently, the hydrophobic adsorption and electrostatic interaction accounted for 71.3 % and 19.75 % for PFOA, while 86.26 % and 5.85 % for PFOS removal, respectively through the solvent extraction and long-term effective removal experiments. Overall, this study provided an alternative, promising and environmental-friendly mZVMg for rapid adsorption of PFOA and PFOS.

Perfluorooctanoic Acids (PFOA) removal using electrochemical oxidation: A machine learning approach

The urgent need to eliminate Perfluorooctanoic Acid (PFOA) has positioned electrooxidation (EO) as a key solution for pollutant degradation. This study evaluates several machine learning (ML) models, including K-Nearest Neighbors (KNN), Decision Tree (DT), Random Forest (RF), Gradient Boosted Decision Trees (GBDT), and Deep Learning (DL), to predict EO efficiency in PFOA removal. Using 10-fold cross-validation, the RF model outperformed others with a root mean square error (RMSE) of 7.7 and a correlation coefficient of 0.965, demonstrating its robustness and accuracy across diverse operational settings. Feature importance within the RF model was analyzed using Gini impurity and Mean Decrease in Accuracy (MDA). Electrolysis Time consistently emerged as the most influential factor in both analyses, underscoring its pivotal role in providing extended exposure of PFOA molecules to reactive species at the electrode surfaces. The study also found strong agreement between Gini and MDA in identifying Current Density and Anode Material as critical factors, although MDA placed slightly more emphasis on Anode Material. Differences between Gini and MDA were more pronounced in the ranking of Electrolyte Type and Concentration, with MDA assigning higher importance to Electrolyte Concentration. In contrast, the Water Matrix was consistently ranked as the least important factor. The strong concordance between Gini and MDA highlights the reliability of the RF model in identifying key drivers of electrochemical degradation. Overall, this work contributes significantly to the advancement of pollutant degradation technologies, presenting a reliable ML-based tool for environmental remediation efforts.

Novel enhanced defluorination of perfluorooctanoic acids by biochar-assisted ultrasound coupling ferrate: Performance and mechanism

An ultrasound (US)/biochar (BC)/ferrate (Fe (VI)) system was firstly proposed to enhance perfluorooctanoic acid (PFOA) defluorination. It achieved 93 % defluorination optimally, higher than the sum of 77 % (28 % and 49 % for US/BC and US/Fe (VI) respectively), implying synergistic effect. Besides, the mechanism study confirmed that, this system can not only increase the specific surface area of BC and the generation of reactive oxidant species (ROS), enriching the active sites and forming new oxygen-containing functional groups, but also promote the formation of intermediate iron species. The PFOA degradation in the US/BC/Fe (VI) was probably an adsorption-degradation process, both ROS and electron transfer promoted the defluorination. Additionally, its sustainability was also demonstrated with 14 % reduced defluorination percentage after five cycles of BC. Overall, the synergistic effect of the US/BC/Fe (VI) and its enhancing mechanism for PFOA defluorination were clarified firstly, which contributes to the development of biochar for assisting polyfluoroalkyl substances degradation.

Detection of Perfluorooctanoic and Perfluorodecanoic Acids on a Graphene-Based Electrochemical Sensor Aided by Computational Simulations

Detection of Perfluorooctanoic and Perfluorodecanoic Acids on a Graphene-Based Electrochemical Sensor Aided by Computational Simulations

Associations between serum per- and polyfluoroalkyl substances and asthma morbidity in the National Health and Nutrition Examination Survey (2003-18).

Per- and polyfluoroalkyl substances (PFAS) are a class of chemicals widely used in manufacturing and are highly resistant to degradation, so they accumulate in the environment. Serum concentrations of these so-called forever chemicals have been associated with impairment of innate and adaptive immune responses. The relationship between serum PFAS levels and asthma morbidity has not been studied. We tested the association between serum PFAS concentration and asthma exacerbations. We performed secondary analysis of data from the National Health and Nutrition Examination Survey (NHANES, 2003-18). We fit multivariable logistic regression models to estimate odds ratios and 95% CIs for asthma exacerbation in the prior 12 months, given serum concentrations of PFAS. Models were adjusted for relevant covariates. Of 1101 participants with self-reported current asthma and available serum PFAS data, we observed that higher serum perfluorooctanoic and perfluorodecanoic acids were associated with greater odds of asthma attacks in the previous 12 months (respectively, adjusted odds ratio 1.16, 95% CI 1.01, 1.33; and adjusted odds ratio 1.21, 95% CI 1.03, 1.43). After stratification by age, the association between perfluorooctanoic acid and asthma attacks was significant in the 12-18-year-old group only (adjusted odds ratio 1.56, 95% CI 1.06, 2.31). No significant relationships were observed between PFAS and asthma-related emergency department visits. After correction for multiple comparison testing, none of the associations reached the threshold of significance. The role of these bioaccumulative forever chemicals in susceptibility to asthma attacks warrants further examination in longitudinal studies. (J Allergy Clin Immunol Global 2023;2:100078.).

A novel enhanced defluorination of perfluorooctanoic acids by surfactant-assisted ultrasound coupling persulfate

A novel enhanced defluorination of perfluorooctanoic acids (PFOA) by surfactant-assisted ultrasound (US) coupling persulfate (PS) was proposed in this study. Instead of adding the surfactant into the PFOA solution directly, the promoted defluorination was obtained by adding the surfactant to the US bath outside of the PFOA reactor. In this situation, the effects of the critical micelle concentration (CMC), concentration and type of the surfactant, the US frequency and the pH of the US bath liquid on the PFOA defluorination were investigated. The results demonstrated that the PFOA defluorination at low-frequency levels (25 kHz-59 kHz) was facilitated by raising US frequency. Besides, the addition of three surfactants (Triton X-100, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB)) all increased the PFOA defluorination by Triton X-100 > CTAB > SDS, which is opposed to their CMC (Triton X-100: 0.28 mM＜CTAB: 1.07 mM＜SDS: 7.69 mM). Rising the surfactant concentration would not enhance the defluorination, the best one was obtained at its CMC. Moreover, changing the pH of the US bath liquid by adding acid or alkaline solution inhibited the defluorination, which might be attributed to acid or base causing damage to the chemical properties or physical structure of surfactant (certified by the SEM tests). Additionally, the mechanism of enhanced PFOA defluorination was examined by electron paramagnetic resonance analysis, which proved that adding surfactant facilitated the generation of the radicals (·OH and SO4∙-), as well as the radicals’ amount increased over time during 60 min. Finally, the inhibited defluorination of adding surfactant directly to the PFOA solution was studied by the SEM analysis, the results demonstrated that adsorption and wrapping between surfactant micelles and PFOA reduced the contact between PFOA and radicals and affected the surfactant effect on the surface tension.

Objective Review

Leather industry uses a great number of processing chemicals to make leather from animal hides. The toxicity, health and environmental impacts of many of these chemicals have been established leading to significant regulatory certifications and programs helping in trade and policy making. The focus of this review are the hazardous chemicals and auxiliaries relevant to leather industry, their categories, possible origins, analysis and toxicity with respect to humans and the environment and the regulatory mechanisms suggested for them through manufacturing restricted substance list (MRSL) 2.0.** Informative guidelines are provided about the most probable leather processing stage for the origin of these chemicals. Some alternative technologies, chemicals and ideas gaining popularity are also suggested as probable remedies. Recommended test methods are stated for the adequate monitoring of the hazardous chemicals. The nature and severity of chemical toxicity and corresponding limits set for their allowed use in formulations are graphically expressed for clarity and ease of understanding. The maximum number of compounds / isomers belong to classes comprising chlorinated paraffins, perfluorooctanoic acids (PFOA), perfluorooctanesulfonates (PFOS) and banned aromatic amines. Similarly, most of the restricted chemicals are used during the finishing stage and may be considered for eco-friendly alternatives. Likewise, the analytical equipment covering most testing requirements is GC-MS among other hyphenated techniques. Additionally, most critical chemicals from toxicity point of view are arsenic, cadmium and chromium (VI), whereas navy blue colorants and chlorinated aromatic compounds may be considered as less toxic among the restricted chemicals under the current scope. Surprisingly, the latest UV absorbents and polymeric fatliquors are comparatively non-toxic. Similarly, the most relaxed formulation limits are given for UV absorbers and 2-methoxypropylacetate whereas strict limits have been set for PFOA, PFOS, mercury, triclosan permethrin, sensitizing dyes etc. in MRSL 2.0.

Disclosing the bioaccumulation and biomagnification behaviors of emerging per/polyfluoroalkyl substances in aquatic food web based on field investigation and model simulation

Emerging poly/perfluoroalkyl substances (PFASs) have been widely detected in the environment, but their bioaccumulation and biomagnification behaviors are not well understood. We collected surface water, sediment, and various aquatic organisms from Lake Taihu, China. Several emerging PFASs, such as fluorotelomer sulfonates (FTSs), hexafluoropropylene oxides (HFPOs), and chlorinated polyfluoroalkyl ether sulfonic acids (Cl-PFESAs) were frequently detected in water and sediment samples. The concentrations of HFPO trimer acid (HFPO-TA), 4,8-dioxa-3 H-per-fluorononanoate, and FTSs were remarkably higher than those reported previously, indicating that their application is increasing in Taihu Basin. These emerging PFASs displayed higher sediment/water partitioning coefficients (log Koc) than the corresponding perfluoroalkyl acids (PFAAs) with the same perfluorinated carbon chain length. HFPOs and Cl-PFESAs were more labile to deposit in fish livers than perfluorooctanoic and perfluorooctane sulfonic acids, respectively. Both field investigations and model simulations indicated that HFPO-TA and Cl-PFESAs, as well as the hydrogen-substituted analogs of 6:2 Cl-PFESA (6:2 H-PFESA), were biomagnified along the aquatic food chain. The bioaccumulation model simulation revealed that the accumulation of these emerging PFASs in fish was mainly through dietary intake, whereas gill respiration and fecal excretion facilitated their elimination. Metabolic transformation might also contribute to their elimination relative to the legacy ones.

Surface engineering of graphene oxide membranes for selective separation of perfluorooctanoic acids

Perfluoroalkyl compounds (PFCs) are environmental toxicants and their widespread detection and accumulation in the environment can be detrimental to the ecosystem. In this study, surface charge of GO membranes was engineered to enhance selectivity of graphene oxide (GO) membranes and for the removal of perfluorooctanoic acid (PFOA ∼400 Da) in real concentration ranges in wastewater streams. The structure and physicochemical properties of the GO and modified GO nanosheets and their corresponding membranes were assessed using several characterization techniques. The modified GO membranes showed a water flux of 83.1 ± 1 L m−2 h−1 together with maximum rejection efficiency of 98.4% for 50 ppm PFOA at pressure of 0.45 MPa, which is the highest value reported to date. Compared to the GO membrane, the modified GO membrane exhibited higher water flux and PFOA rejection efficiency by 300% and 70%, respectively. The high surface charged and electron rich GO nanosheets reduce the interlayer spacing in the modified membrane and simultaneously enhance the surface hydrophilicity which leads to increased PFOA retention and enhanced water permeation. These results point to the potential of the modified GO membranes for wastewater treatment.

A density functional theory study of the simplest adsorption forms of perfluorooctanoic and perfluorooctanesulphonic acids by graphene oxide and fluorinated graphene oxide*

A density functional theory augmented by the long-range corrected hybrid density functional ωB97XD and 6-31G(d,p) basis set has been applied to generate the simplest adsorption structure models of perfluorooctanoic and perfluorooctanesulphonic acids adsorbed from a water solution by the surfaces of graphene oxide and fluorinated graphene oxide. It has been revealed that both hydrophilic and hydrophobic sites can adsorb the anions of the investigated acids. The results of our calculations suggest preference in the adsorption ability of graphene oxide compared to its fluorinated counterpart.

Bottom-up self-assembly of nanofibers in the surfactant mixture of CTAB and Pluronics

Bottom-up self-assembly of nanofibers in a chemical method is presented using the surfactant mixture of cetyltrimethylammonium bromide (CTAB) and Pluronics as the anisotropic micellar templates. Fully fluorinated perfluorooctanoic acids with highly hydrophobic C–F chains are imported for constructing exceptionally long nanofibers. Ag(I) provides robustness of the materials by the complexation with ethylene oxides in Pluronic copolymers. Fluorocarbons reside in the PPO (polypropylene oxide) blocks in Pluronic polymers and accordingly in reverse Pluronics, they are placed in the surrounding regions of nanofibers. During the segregation of water from hydrophobic cores, self-assembly is assumed to be driven by hydrophobic interactions among alkyl chains of CTAB, fluoroalkyl chains of perfluorooctanoic acids, and dehydrated methyl groups of PPO blocks in Pluronics. Nanofibers with relatively high aspect ratios were obtained when Pluronic copolymers with low number average molecular weights (Mn), such as L-31 (Mn ∼ 1100) and L-64 (Mn ∼ 2900), were used. Heterogeneous catalytic activities were monitored in the reduction reactions of 4-nitrophenol, and the nanorods prepared from Pluronic 31R1 show the best catalytic performances with a rate constant of 0.002 35 s−1. The roles of fluorine or C–F groups in perfluorooctanoic acids are believed to be the disruption of hydrogen bonding between water and polyethylene oxide groups, and the phase separation of nanofibers from the aqueous environment by the dehydration of hydrophobic cores.

Selective sequestration of perfluorinated compounds using polyaniline decorated activated biochar

Poly- and perfluorinated compounds (PFCs) in wastewater could induce the poisonous effects to the living beings throughout the world. In this present investigation, polyaniline (PANI) decorated activated biochar (AB) hybrid composite (AB@x%PANI, x = 0%, 25%, 50%, 75%, and 100% of PANI) was fabricated for PFCs adsorption via in situ chemical oxidation and co-precipitation with calcination. The physical and chemical properties of AB@x%PANI before and after adsorption were characterized by FTIR, PXRD, XPS, FE-SEM with EDX, HR-TEM, 13C NMR, and TGA analysis. Batch experiments for the effect of contact time, initial PFCs concentration, solution pH, and co-existing cations were conducted for the maximum adsorption capacity of as-synthesized adsorbents. The AB@75%PANI hybrid composite exhibited higher adsorption capacity for the removal of perfluorooctanoic, perfluorooctanesulfonic, and perfluorohexanesulfonic acids than powdered activated carbon, AB, PANI, AB@25%PANI, and AB@50%PANI. The adsorption isotherm and kinetic results demonstrated that the adsorption system using AB@75%PANI hybrid composite followed pseudo-second-order and Langmuir isotherm models. The PFCs adsorption by AB@75%PANI was mainly governed by various interaction forces such as hydrogen bonding, electrostatic attraction, hydrophobic interaction, and surface complexation in the presence of co-existing cations. These findings shed light on how to selectively eliminate PFCs from wastewater.

Esterification of perfluorinated carboxylic acids with bromomethyl aromatic compounds for gas chromatography combined with laser ionization mass spectrometry

Perfluorinated carboxylic acids (PFCAs) were derivatized with two types of aromatic compounds that contained a bromomethyl group, i.e., 2-(bromomethyl)naphthalene (BMN) and benzyl bromide (BB). The conditions for derivatization were optimized in terms of reaction temperature and time and the concentration of derivatizing reagent. Using these optimal conditions, the PFCAs-MN and PFCAs-B derivatives were measured by gas chromatography (GC) combined with mass spectrometry using an ultraviolet femtosecond laser (267 nm) as the ionization source. The efficiency of derivatization for PFCAs-B was higher than that for PFCAs-MN because of the smaller size of the chromophore (benzene). The ionization efficiency of PFCAs-MN, however, was better than PFCAs-B, since a larger sized chromophore (naphthalene) and then a larger molar absorptivity was preferable for resonance-enhanced two-photon ionization. Due to superior GC separation, BB was successfully used as the derivatizing agent for the trace analysis of PFCAs, with detection limits of 6.0, 8.4, and 9.5 ng/mL for perfluoroheptanoic, perfluorooctanoic, and perfluorononanoic acids, respectively. The other bromomethyl aromatic compounds were evaluated for use as a derivatization reagent in future studies.

Surface modification of sodium bicarbonate ultrafine powder extinguishing agent by environmental friendly fluorinated acrylate copolymers

Common ultrafine powder fire extinguishing agent couldn't put out the oil fire. To solve this problem, a simple and controllable way for preparing hydrophobic and oleophobic fire extinguishing agent was developed. Firstly, fluorinated acrylate copolymers (FP) with different fluorine contents were prepared and used to modify the extinguishing agent. Unlike perfluorooctane sulphonate/ perfluorooctanoic acids (PFOS/PFOA) with C8-fluorocarbon chains widely used as modifiers, the prepared FP with C6-fluorocarbon chains not only met the environmental standards, but also possessed excellent properties. Subsequently, the fluorine contents of particles modified by two FP were 19.3% and 37.4% respectively. The contact angles of deionized water were 103.5° and 117° respectively, and those of aviation kerosene were 68° and 120.5° respectively. They possessed outstanding hydrophobicity, but particles modified by FP2 had better oleophobicity. Finally, the particles covered the surface of fuel, which prevented the fuel from evaporating. Combined with the effect of interrupting the combustion chain reaction, the flame was gradually extinguished.

Contaminants of emerging concern in drinking water: Quality assessment by combining chemical and biological analysis

Drinking water quality is a priority issue of the environmental policy agenda, however regulation on Contaminants of Emerging Concern (CECs) is limited. A proposal to revise the Drinking Water Directive has recently been approved (EU Council 2020), which updates the quality standards and introduces the watch list mechanism, including for the first time endocrine disruptors and pharmaceuticals. The purpose of this study was to evaluate the occurrence of selected CECs in surface water at the entrance of drinking water treatment plants (DWTPs) and in treated water, ready for distribution in the network. Samples were collected at three different DWTPs (Italy) and CECs assessed by LC-MS/MS were the following: bisphenol A (BPA), nonylphenol (NP), octylphenol, perfluorooctanesulfonic and perfluorooctanoic acids (PFOS and PFOA), atenolol, caffeine (CFF), carbamazepine (CBZ), estrone, 17-β-estradiol, 17-α-ethinyl estradiol, diclofenac, and ibuprofen. In addition, biological analyses were performed to ascertain cumulative estrogenic and/or genotoxic potential of the samples. CFF, NP, PFOA, BPA, and CBZ were the most frequently detected contaminants, found in treated water in the following ranges: CFF 12.47–66.33 ng/L, NP 7.90–53.62 ng/L, PFOA <LOQ-12.66, ng/L, BPA <LOQ-6.27 ng/L, and CBZ <LOQ-1.20 ng/L. While treatments were generally efficacious in reducing BPA, CFF and CBZ, they were sometimes ineffective for NP and PFOA. According to the low concentrations and/or regulation limit for each single contaminant, the water analyzed met the criteria of good quality. No estrogenic or genotoxic activities were induced by the water assessed, with the exception of one sample.It has been suggested that drinking water may not represent a significant source of human exposure to CECs, however co-occurrence of different compounds may lead to additive/synergistic interactions causing unexpected effects on human health and the environment, and deserve implementation of strategies for detection and removal.

Mesoporous adsorbents for perfluorinated compounds

Abstract Effective adsorbents for polyfluorinated compounds (PFCs) were obtained and successfully tested in adsorption of perfluorooctanoic and perfluorooctanesulfonic acids. Bridged silsesquioxanes containing secondary and tertiary amino groups were synthesized by sol-gel condensation of bis[3-(trimethoxysilyl)propyl]amine and N-methyl-3,3′-bis(trimethoxysilyl)dipropylamine in acidic media in the presence of surfactants. Obtained materials were mesoporous with high BET surface area. They combine high structural stability with high concentration of surface amino groups serving as adsorption sites. Batch adsorption tests demonstrated their high adsorption capacity on PFCs: in some experiments it reached up to 88% of the adsorbent weight. Adsorption of PFCs changed the surfaces of the adsorbent nanoparticles from hydrophilic to hydrophobic thus providing their agglomeration and floatability. Column tests showed fast adsorption of PFCs even at high concentrations and high flow rates. Obtained results can be used in the development of an effective filtration device for clean-up of water contaminated by PFCs.

Probing Mechanisms for the Tissue-Specific Distribution and Biotransformation of Perfluoroalkyl Phosphinic Acids in Common Carp (Cyprinus carpio).

This study investigated the tissue-specific accumulation and biotransformation of 6:6 and 8:8 perfluoroalkyl phosphinic acids (PFPiA) in common carp (Cyprinus carpio) during 90 d exposure and 30 d depuration in water in the laboratory. Both 6:6 and 8:8 PFPiAs could quickly accumulate in the carp, and 6:6 PFPiA displayed higher bioaccumulation potential than 8:8 PFPiA. The highest concentrations of PFPiAs were observed in the blood, while the lowest were found in the muscle. The equilibrium dialysis experiment indicated that both PFPiAs had higher binding affinities with the proteins in the fish serum than in liver, which was supported by the molecular docking analysis. The results also indicated that 6:6 PFPiA had higher binding affinities with the serum and liver proteins than 8:8 PFPiA. These results suggested that the tissue-specific distribution of PFPiAs was highly dependent on the binding affinities with the specific proteins. Both in vivo and in vitro experiments consistently indicated that PFPiAs experienced biotransformation and produced perfluoroalkyl phosphonic acids (PFPAs), and biotransformation of 8:8 PFPiA was more active than 6:6 PFPiA. It was worth noting that perfluorohexanonate and perfluorooctanoic acids were identified in fish as metabolites after long-term exposure to PFPiAs for the first time.

Comparative performance of TiO2-rGO photocatalyst in the degradation of dichloroacetic and perfluorooctanoic acids

Halogenated organic compounds are frequently characterized by their bioaccumulative nature, and long­term effects on human health. Their low biodegradability and their difficult removal by conventional technologies lead to their undesirable persistence in the environment. Titanium dioxide and reduced graphene oxide TiO2-rGO composites have shown promising results with enhanced photocatalytic degradation rates compared to bare TiO2 in the degradation of a good number of persistent pollutants. In this context, this work deepens on the influence of the type and number of halogen substitution on the photocatalytic degradation of halogenated organic compounds (HOCs). For the experimental analysis two HOCs, dichloroacetic acid (DCA) and perfluorooctanoic acid (PFOA), have been selected as both molecules differ in the type of halogen atoms, chlorine and fluorine, the number of halogen atoms, and in the length of the alkyl chain. The results showed that TiO2-rGO catalysts achieved a similar kinetic performance for the removal of the primary contaminant in terms of its degradation rate. Besides, TiO2-rGO composite successfully induced the release of all chlorine atoms from the DCA molecule, achieving its total mineralization. However, PFOA defluorination and mineralization rates were remarkably lower than its degradation rate. Although both contaminants released two halogen atoms step-by-step for the degradation of each molecule, PFOA dehalogenation was slowed down due to the generation of secondary products that retain fluorine. Therefore, we conclude that the composite photocatalysts showed a similar performance in terms of degradation rate of the primary contaminant independent on the length of the alkyl chain and on the number of halogen atoms, however, the mineralization and dehalogenation rates were strongly dependent on the number of halogen substituents and the length of the alkyl chain.

Experimental investigation on the perfluorooctanoic and perfluorooctane sulfonic acids fate and behaviour in the activated sludge reactor

Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are the most investigated compounds in the class of perfluoroalkyl substances for their persistence and wider diffusion in the environment. However, fate and behaviour of PFOA and PFOS in the Wastewater Treatment Plants (WWTPs) have not been fully understood yet. The aim of the present study was to obtain a better understanding of the processes occurring to PFOS and PFOA in the activated sludge reactor. Several experimental tests were performed in the presence of activated sludge and sterilized sludge. PFOA and PFOS showed removals from the liquid phase from 59 % to 68 % and from 66 % to 96 %, respectively, for initial concentrations from 200ng/L to 4000ng/L in the presence of activated sludge. A significant fraction of the initial contaminant load was found adsorbed on the sludge, mainly in the case of PFOS. Other processes occurred, not fully identified, which were responsible of a further loss from the system. Leaching tests showed negligible release of the adsorbed pollutants from the sludge. Carbon and ammonia removal in the activated sludge reactor were not significantly affected by the presence of PFOA and PFOS. The pseudo-second order kinetic model and the Freundlich isotherm provided the best fitting of the experimental data.

Direct effects of organic pollutants on the growth and gene expression of the Baltic Sea model bacterium Rheinheimera sp. BAL341.

SummaryOrganic pollutants (OPs) are critically toxic, bioaccumulative and globally widespread. Moreover, several OPs negatively influence aquatic wildlife. Although bacteria are major drivers of the ocean carbon cycle and the turnover of vital elements, there is limited knowledge of OP effects on heterotrophic bacterioplankton. We therefore investigated growth and gene expression responses of the Baltic Sea model bacterium Rheinheimera sp. BAL341 to environmentally relevant concentrations of distinct classes of OPs in 2‐h incubation experiments. During exponential growth, exposure to a mix of polycyclic aromatic hydrocarbons, alkanes and organophosphate esters (denoted MIX) resulted in a significant decrease (between 9% and 18%) in bacterial abundance and production compared with controls. In contrast, combined exposure to perfluorooctanesulfonic acids and perfluorooctanoic acids (denoted PFAS) had no significant effect on growth. Nevertheless, MIX and PFAS exposures both induced significant shifts in gene expression profiles compared with controls in exponential growth. This involved several functional metabolism categories (e.g. stress response and fatty acids metabolism), some of which were pollutant‐specific (e.g. phosphate acquisition and alkane‐1 monooxygenase genes). In stationary phase, only two genes in the MIX treatment were significantly differentially expressed. The substantial direct influence of OPs on metabolism during bacterial growth suggests that widespread OPs could severely alter biogeochemical processes governed by bacterioplankton.