4 Material und Umwelt
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- 4 Material und Umwelt (3) (entfernen)
For the first time, fluorine K-edge X-ray absorption near-edge structure (XANES) spectroscopy was applied to detect per- and polyfluoroalkyl substances (PFAS) in various soil and sewage sludge samples. The method can be used to determine the speciation of inorganic and organic fluorides, without pre-treatment of solid samples. Therefore, XANES spectra of several inorganic fluorides as well as selected fluorinated organic compounds were recorded. While inorganic fluorides partially exhibit a variety of sharp spectral features in the XANES spectrum, almost all inspected organofluorine compounds show two distinct broad features at 688.5 and 692.0 eV. Moreover, the peak intensity ratio 688.5 eV/692.0 eV in the PFAS XANES spectrum can be inversely correlated to the chain length of the perfluoro sulfonic acid group. The detection of targeted PFAS by bulk-XANES spectroscopy in combination with linear combination fitting in soils and sewage sludges was not applicable due to the low organic fluorine to total fluorine ratio of the samples (0.01–1.84%). Nonetheless, direct analysis of pure PFAS revealed that analysis of organofluorine species might be achieved in higher concentrated samples. Furthermore, quantitative measurements by combustion ion chromatography (CIC) evaluated as sum parameters extractable organically bound fluorine (EOF) and total fluorine (TF) emphasize that besides soils, sewage sludges are a significant source of organic fluorine in agriculture (154–7209 μg/kg).
Per- and polyfluoralkyl surfactants (PFAS) are industrially produced surface chemicals used in daily applications that have gained public and political attention due their unnaturally high appearance in drinking water, nourishments and soils.[1] Their chemical structures exhibit both lipophilic and hydrophilic properties, leading to a highly inert and persistent character.[2] Various PFAS have shown to be bioaccumulative in plants and animals, and some have been characterized as highly toxic when ingested.[3] When exposed to the environment, PFAS slowly get mobilized by natural water resources, leading to contamination of large areas of soil and natural water sources.[4] While PFAS contamination of drinking water has been investigated intensively, perfluoralkyl contamination of soils has been rarely examined as of yet. At the same time, an increasing amount of PFAS contamination sites are being discovered worldwide, calling for a sophisticated strategy towards analytical characterization.[5] Since the number of known PFAS already exceeds 4700, the established sum parameters like extractable organic fluorine (EOF) and adsorbable organic fluorine (AOF) are key elements to fully survey the impact of exposure.[6] Simultaneously, innovative soil remediation strategies are required to contain environmental destruction and to minimize further spreading of contaminants.[7] Addressing these challenges requires suitable analytical devices that are capable of mobilizing PFAS in the solid as well as in the liquid phase. The use of combustion ion chromatography (CIC) enables analysis of both immobile and volatile PFAS and allows the detection of both total fluorine (TF) and EOF or AOF of a given soil or aqueous sample. Based on preliminary results, the clean-up of a PFAS contaminated matrix is monitored via EOF detection over time. Additionally, we tested the effectiveness of urea (CH₄N₂O) as fluoride scavenger with the aim to improve the separation of inorganic and organic fluorine and therefore, to improve AOF accuracy. The presented findings can be contributive with regard to future AOF/EOF sum parameter development and application.
Per- and polyfluoralkyl surfactants (PFASs) are industrially produced surface chemicals used in daily applications that have gained public and political attention due their unnaturally high appearance in drinking water, nourishments and soils. Their chemical structures exhibit both lipophilic and hydrophilic properties, leading to a highly inert and persistent character. Various PFASs have shown to be bioaccumulative in plants and animals, and some have been characterized as highly toxic when ingested. When exposed to the environment, PFASs slowly get mobilized by natural water resources, leading to contamination of large areas of soil and natural water sources. While PFASs contamination of drinking water has been investigated intensively, perfluoralkyl contamination of soils has been rarely examined as of yet. At the same time, an increasing amount of PFASs contamination sites are being discovered worldwide, calling for a sophisticated strategy towards analytical characterization. Since the number of known PFASs already exceeds 4700, the established sum parameters like extractable organic fluorine (EOF) and adsorbable organic fluorine (AOF) are key elements to fully survey the impact of exposure. Simultaneously, innovative soil remediation strategies are required to contain environmental destruction and to minimize further
spreading of contaminants. Addressing these challenges requires suitable analytical devices that are capable of mobilizing PFASs in the solid as well as in the liquid phase. The use of combustion ion
chromatography (CIC) enables analysis of both immobile and volatile PFASs and allows the detection of both total fluorine (TF) and EOF or AOF of a given soil or aqueous sample. Based on preliminary results, the clean-up of a PFAS contaminated solid matrix is monitored via EOF detection over time.
Additionally, we demonstrate the pH dependency of hydrogen fluoride absorption on active carbon (AC) and found a simple organic additive to be an effective fluoride scavenger. The presented findings can be contributive with regard to future AOF/EOF sum parameter development and application.