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MOF-based Electrochemical Sensors for Endocrine-disrupting Compounds
Published in Ram K. Gupta, Tahir Rasheed, Tuan Anh Nguyen, Muhammad Bilal, Metal-Organic Frameworks-Based Hybrid Materials for Environmental Sensing and Monitoring, 2022
Yukun Yang, Zhuo Shi, Wenyan Yan, Xiaomin Wang, Jinhua Zhang, Ligang Yu, Caixia Guo, Baoqing Bai
Perfluorooctane sulfonate (PFOS) has been widely used in civil, military, commercial, and industrial fields in the past few decades, which is commonly known as perfluoro and polyfluoroalkyl substances (PFAS). Many health concerns, such as obesity, endocrine disruption, immune suppression, and even cancer are related to PFOS exposure. Meanwhile, environmental stability and physiological persistence of PFOS are also serious problems. Cheng et al. constructed a synergistic approach for the targeted affinity-based capture of PFOS using MOFs as porous sorbent probes, which could enhance the detection sensitivity of a microfluidic platform [45]. Schematics of PFOS detection are shown in Figure 28.9. This novel platform functioned as a MOF-based electrochemical sensor to directly measure PFOS concentration through a proportional change in electrical signal (increase in impedance). The nanoporous geometry of MOFs, along with interdigitated microelectrodes, increased the signal-to-noise ratio tremendously. Further, the porose MOF-based capture probes could interact with PFOS at molecular level and effectively enhance the sensitivity. The detection limit of 0.5 ng L−1 was achieved unprecedently for in-situ analytical sensors of PFOS.
Activated Sludge Process for Refractory Pollutants Removal
Published in Maulin P. Shah, Removal of Refractory Pollutants from Wastewater Treatment Plants, 2021
Reyhan Ata, Gökçe Faika Merdan, Günay Yıldız Töre
The strong structure of carbon-fluorine bonds is the factor that makes perfluoroalkyl chains resistant to biodegradation and stabilize over wide temperature, pH, and pressure ranges. The persistence, toxicity, and bioaccumulation potential of certain perfluoroalkyl chain lengths of perfluoroalkyl carboxylic and sulfonic acids (PFCAs and PFSAs, respectively) have resulted in numerous phase-outs and bans worldwide. The introduction of PFOAs into the environment occurs through various mechanisms, such as the active use of fire-fighting surfactants, discharge from chemical production facilities (i.e., air emissions or wastewater), improperly treated wastewater, and the improper disposal of household products produced with PFAs. Studies have shown that PFOS can bioaccumulate in the human body by oral, inhalation, and dermal routes or by consuming contaminated seafood and drinking water. PFOS taken into the human body through diet can cause serious toxic effects such as liver toxicity, developmental toxicity, and immunotoxicity. It may also have negative effects on reproductive organs, cause endocrine disrupting effects, and increase the risk of breast cancer. Consequently, poly- and perfluoroalkyl substances (PFASs), which are not biodegradable due to their high thermal and chemical stability, are widely distributed in the environment, especially in the receiving aquatic environment (Saikat et al. 2013).
Perfluoroalkyl Substance Toxicity from Early-Life Exposure
Published in David M. Kempisty, Yun Xing, LeeAnn Racz, Perfluoroalkyl Substances in the Environment, 2018
In May 2016, the US Environmental Protection Agency (USEPA) published advisory levels for PFOA and PFOS at 70 parts per trillion (ppt) in drinking water to account for the chronic effects of these toxicants (USEPA 2016). The basis of this advisory level relied heavily on animal studies that reported a variety of toxicity, including skeletal variations (delay in ossification of phalanges), testicular cancer, and persistent liver effects (Figure 9.1). Skeletal variations had a particularly large impact on the advisory level since it was reported to occur at the lowest dose (Lau et al. 2006). Delayed mammary gland development was also discussed but was ultimately dismissed due to an unknown mode of action, strain differences in mice, and unclear functional significance. This section reviews the literature surrounding adiposity and developmental (including both phalanges ossification and mammary gland development) toxicity since these are primarily observed effects resulting from early-life or prenatal exposure, as well as other toxicities reported from early-life exposure.
A density functional theory study of the simplest adsorption forms of perfluorooctanoic and perfluorooctanesulphonic acids by graphene oxide and fluorinated graphene oxide*
Published in Molecular Physics, 2022
Leonid Gorb, Mykola Ilchenko, Jerzy Leszczynski
Because of their resistance to numerous methods of chemical degradation, the main approach to remove PFOA and PFOS from the water bulk is represented by the technologies based on adsorption. However, to the best of our knowledge, the analysis of current publications reveals the lack of fundamental research devoted to studying the interaction of PFOA and PFOS with graphene and graphene oxide derivatives. In particular, there are only two publications where density functional theory has been applied to investigate adsorption properties of graphene oxide and fluorinated graphene interacting with PFOA and PFOS in the gas phase [19,20]. Taking this point into account, using density functional theory, we have predicted and compared the interactions of PFOA and PFOS with two computationally designed model adsorption surfaces that mimic the surface of graphene oxide and fluorinated graphene oxide.
Developing innovative treatment technologies for PFAS-containing wastes
Published in Journal of the Air & Waste Management Association, 2022
Chelsea Berg, Brian Crone, Brian Gullett, Mark Higuchi, Max J. Krause, Paul M. Lemieux, Todd Martin, Erin P. Shields, Ed Struble, Eben Thoma, Andrew Whitehill
While ingestion of contaminated food has been identified as the primary PFOA exposure pathway for the general population, drinking water can become the primary exposure pathway in communities with contaminated water (Vestergren and Cousins 2009). To provide protection from long term exposure to PFOS and PFOA in drinking water, the U.S. EPA established drinking water health advisory concentration limits for PFOS and PFOA of 70 ng/L in 2016 (U.S. EPA 2016a, 2016b). To meet these limits, granular activated carbon (GAC) and anion exchange resins (AEX) have been utilized as treatment methods for separating PFAS from liquid streams, often at a fraction of the cost of other separation technologies such as nanofiltration and reverse osmosis (Dickenson and Higgins 2016). GAC and AEX are commonly used to separate PFAS from liquid streams during groundwater site remediation and manufacturing as well as drinking water treatment. GAC removes PFAS compounds from liquid by surface adsorption whereas AEX involves ion exchange onto a positively-charged surface. The surfaces of both materials become saturated over time and no longer able to remove PFAS. GAC can be regenerated but eventually loses its effectiveness and must be disposed. AEX resins used for treatment of PFAS may or may not be amenable to regeneration. Spent GAC and AEX are currently either landfilled or incinerated. The former may lead to PFAS ending up in the landfill leachate.
The transplacental transfer efficiency of per- and polyfluoroalkyl substances (PFAS): a first meta-analysis
Published in Journal of Toxicology and Environmental Health, Part B, 2022
Mareike Appel, Martin Forsthuber, Romualdo Ramos, Raimund Widhalm, Sebastian Granitzer, Maria Uhl, Markus Hengstschläger, Tanja Stamm, Claudia Gundacker
The most frequently detected PFAS in humans, according to the European Food Safety Authority (EFSA), are PFOS, PFOA, perfluorohexanesulfonic acid (PFHxS) and perfluorononanoic acid (PFNA). According to a recent risk assessment, adverse health effects attributed to PFOS, PFOA, PFHxS and PFNA include decreased response to vaccination, increased liver weight, disturbances in lipid metabolism and reduced fetal weight and/or postnatal growth (EFSA 2020). Similarly, the United States Environmental Protection Agency (US.EPA) and the Agency for Toxic Substances and Disease Registry (ATSDR) concluded that PFAS may exert an impact on birth weight (US.EPA. 2016, 2019) and that PFOA affects fetal growth (ATSDR 2021). Systematic reviews and original investigations found evidence that PFOS, PFOA, and PFHxS are associated with lower average birth weight (Alkhalawi et al. 2016; Bach et al. 2015), while exposure to PFOS, PFOA, and PFNA during pregnancy may be associated with increased risk of preterm birth, miscarriage, and preeclampsia (Gao et al. 2021).