“…In a sulfate radical-based process investigated by Lee et al ( 2009 ), only 12.7% PFOA removal took place in landfill leachate. In the presence of Cl, species such as ClO − , Cl 2 , Cl • , and HClO are electrogenerated at the anode surface and act through indirect oxidation of PFOA (Mojiri et al 2023 ). Fig.…”
Section: Resultsmentioning
confidence: 99%
“…PFOA specifically has been used in the production of non-stick cookware, water-repellent clothing, stain-resistant fabrics, and in certain firefighting foams, particularly those used at air bases and airports. PFOA is employed for polymerization in the manufacturing of various fluoropolymers, which have been applied in various industrial and consumer products such as Gore-Tex and Teflon (Mojiri et al 2023 ). The widespread use of PFAS in various products and industrial processes has led to their presence in the environment, including water sources, soil, and even in the bodies of animals and humans.…”
Perfluorooctanoic acid (PFOA) is a bioaccumulative synthetic chemical containing strong C–F bonds and is one of the most common per- and polyfluoroalkyl substances (PFAS) detected in the environment. Graphite intercalated compound (GIC) flakes were used to adsorb and degrade PFOA through electrochemical oxidation. The adsorption followed the Langmuir model with a loading capacity of 2.6 µg PFOA g−1 GIC and a second-order kinetics (3.354 g µg−1 min−1). 99.4% of PFOA was removed by the process with a half-life of 15 min. When PFOA molecules broke down, they released various by-products, such as short-chain perfluoro carboxylic acids like PFHpA, PFHxA, and PFBA. This breakdown indicates the cleavage of the perfluorocarbon chain and the release of CF2 units, suggesting a transformation or degradation of the original compound into these smaller acids. Shorter-chain perfluorinated compounds had slower degradation rates compared to longer-chain ones. Combining these two methods (adsorption and in situ electrochemical oxidation) was found to be advantageous because adsorption can initially concentrate the PFOA molecules, making it easier for the electrochemical process to target and degrade them. The electrochemical process can potentially break down or transform the PFAS compounds into less harmful substances through oxidation or other reactions.
“…In a sulfate radical-based process investigated by Lee et al ( 2009 ), only 12.7% PFOA removal took place in landfill leachate. In the presence of Cl, species such as ClO − , Cl 2 , Cl • , and HClO are electrogenerated at the anode surface and act through indirect oxidation of PFOA (Mojiri et al 2023 ). Fig.…”
Section: Resultsmentioning
confidence: 99%
“…PFOA specifically has been used in the production of non-stick cookware, water-repellent clothing, stain-resistant fabrics, and in certain firefighting foams, particularly those used at air bases and airports. PFOA is employed for polymerization in the manufacturing of various fluoropolymers, which have been applied in various industrial and consumer products such as Gore-Tex and Teflon (Mojiri et al 2023 ). The widespread use of PFAS in various products and industrial processes has led to their presence in the environment, including water sources, soil, and even in the bodies of animals and humans.…”
Perfluorooctanoic acid (PFOA) is a bioaccumulative synthetic chemical containing strong C–F bonds and is one of the most common per- and polyfluoroalkyl substances (PFAS) detected in the environment. Graphite intercalated compound (GIC) flakes were used to adsorb and degrade PFOA through electrochemical oxidation. The adsorption followed the Langmuir model with a loading capacity of 2.6 µg PFOA g−1 GIC and a second-order kinetics (3.354 g µg−1 min−1). 99.4% of PFOA was removed by the process with a half-life of 15 min. When PFOA molecules broke down, they released various by-products, such as short-chain perfluoro carboxylic acids like PFHpA, PFHxA, and PFBA. This breakdown indicates the cleavage of the perfluorocarbon chain and the release of CF2 units, suggesting a transformation or degradation of the original compound into these smaller acids. Shorter-chain perfluorinated compounds had slower degradation rates compared to longer-chain ones. Combining these two methods (adsorption and in situ electrochemical oxidation) was found to be advantageous because adsorption can initially concentrate the PFOA molecules, making it easier for the electrochemical process to target and degrade them. The electrochemical process can potentially break down or transform the PFAS compounds into less harmful substances through oxidation or other reactions.
“…Advanced oxidation processes (AOPs) have emerged as highly effective strategies for contaminant removal, owing to the radicals they generate in situ, such as hydroxyl (•OH), superoxide (•O 2− ), and sulfate (•SO 4− ) radicals. The simplicity of AOP operation, coupled with mild reaction conditions and high efficiency, has garnered significant interest in recent years [81,82]. The potent oxidizing nature of these radicals not only breaks down organic pollutants but also mitigates their toxicity and, in some instances, mineralizes them into CO 2 [83,84].…”
Over the last few decades, there has been a growing discourse surrounding environmental and health issues stemming from drinking water and the discharge of effluents into the environment. The rapid advancement of various sewage treatment methodologies has prompted a thorough exploration of promising materials to capitalize on their benefits. Metal–organic frameworks (MOFs), as porous materials, have garnered considerable attention from researchers in recent years. These materials boast exceptional properties: unparalleled porosity, expansive specific surface areas, unique electronic characteristics including semi-conductivity, and a versatile affinity for organic molecules. These attributes have fueled a spike in research activity. This paper reviews the current MOF-based wastewater removal technologies, including separation, catalysis, and related pollutant monitoring methods, and briefly introduces the basic mechanism of some methods. The scale production problems faced by MOF in water treatment applications are evaluated, and two pioneering methods for MOF mass production are highlighted. In closing, we propose targeted recommendations and future perspectives to navigate the challenges of MOF implementation in water purification, enhancing the efficiency of material synthesis for environmental stewardship.
“…They are used in a broad range of products due to their unique physiochemical properties and it is these properties that result in the persistence of PFAS in the environment. It has been clear for quite some time that PFAS are persistent and widely distributed in aquatic ecosystems (Ankley et al, 2021;Holder et al, 2023;Miranda et al, 2022;Mojiri et al, 2023). Some of the earliest developed PFAS (i.e., perfluorooctanesulfonic acid [PFOS] and perfluorooctanoic acid [PFOA]) have received considerable attention within the last several decades, and although they are no longer manufactured, they are routinely detected in aquatic ecosystems (Breitmeyer et al, 2023;Ehsan et al, 2023).…”
As part of the US Environmental Protection Agency's perfluoroalkyl and polyfluoroalkyl substances (PFAS) Action Plan, the agency is committed to increasing our understanding of the potential ecological effects of PFAS. The objective of these studies was to examine the developmental toxicity of PFAS using the laboratory model amphibian species Xenopus laevis. We had two primary aims: (1) to understand the developmental toxicity of a structurally diverse set of PFAS compounds in developing embryos and (2) to characterize the potential impacts of perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), and hexafluoropropylene oxide‐dimer acid (HFPO‐DA a.k.a. GenX), on growth and thyroid hormone‐controlled metamorphosis. We employed a combination of static renewal and flow‐through exposure designs. Embryos were exposed to 17 structurally diverse PFAS starting at the midblastula stage through the completion of organogenesis (96 h). To investigate impacts on PFOS, PFOA, PFHxS, and HFPO‐DA on development and metamorphosis, larvae were exposed from premetamorphosis (Nieuwkoop Faber stage 51 or 54) through pro metamorphosis. Of the PFAS tested in embryos, only 1H,1H,10H,10H‐perfluorodecane‐1,10‐diol (FC10‐diol) and perfluorohexanesulfonamide (FHxSA) exposure resulted in clear concentration‐dependent developmental toxicity. For both of these PFAS, a significant increase in mortality was observed at 2.5 and 5 mg/L. For FC10‐diol, 100% of the surviving embryos were malformed at 1.25 and 2.5 mg/L, while for FHxSA, a significant increase in malformations (100%) was observed at 2.5 and 5 mg/L. Developmental stage achieved was the most sensitive endpoint with significant effects observed at 1.25 and 0.625 mg/L for FC10‐diol and FHxSA, respectively. In larval studies, we observed impacts on growth following exposure to PFHxS and PFOS at concentrations of 100 and 2.5 mg/L, respectively, while no impacts were observed in larvae when exposed to PFOA and HFPO‐DA at concentration of 100 mg/L. Further, we did not observe impacts on thyroid endpoints in exposed larvae. These experiments have broadened our understanding of the impact of PFAS on anuran development.
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