TY - JOUR A1 - Zhuang, Yiling A1 - Haderlein, Stefan B. A1 - Hagemann, Nikolas A1 - Grafmüller, Jannis A1 - Gogler, Karolin A1 - Paul, Andrea A1 - Fink, Friedrich A1 - Spahr, Stephanie T1 - Activation of persulfate by biochar and iron: role of biochar pyrolysis conditions and ash amendments N2 - Redox-active biochars can enhance contaminant transformation in persulfate-based Fenton-like water treatment by facilitating Fe(III) reduction to Fe(II). However, biochar properties vary greatly depending on both feedstock selection and pyrolysis conditions. Best suited biochars for Fe(III) reduction and persulfate activation have yet to be identified. Here, we investigated eight biochars for their ability to activate persulfate with Fe(III) to transform N,N-diethyl-m-toluamide (DEET) in water. Four of the biochars were produced from beech wood under different pyrolysis conditions (450–750 °C, high and low nitrogen flow rate in the reactor) and four biochars were produced from softwood amended with 0 – 43 weight percent (wt%) wood ash prior to pyrolysis at 500 °C. Beech wood biochar produced at 450 °C transformed DEET most efficiently with a half-life time of 39 ± 4 min, likely due to the high concentration of surface oxygen functional groups and persistent free radicals that accelerated Fe(III) reduction and formation of reactive species. Among the ash-amended biochars, biochar with 16 wt% ash amendment showed the most efficient DEET transformation with a half-life time of 27 ± 0.6 min, which is 10-times faster compared to a non-ash-amended biochar produced from the same biomass under similar pyrolysis conditions. Ash amendment led to the formation of crystalline iron minerals in biochars, which likely promoted Fe(III) reduction and persulfate activation. Our results highlight the potential for fine-tuning the redox properties of biochar, e.g., by ash amendment to a woody feedstock, enabling tailored performance for specific water treatment applications. KW - Persistent free radicals KW - Redox-active moieties KW - Fenton-like systems PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-634504 DO - https://doi.org/10.1016/j.seppur.2025.133634 SN - 1383-5866 VL - 374 SP - 1 EP - 8 PB - Elsevier B.V. AN - OPUS4-63450 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Paul, Andrea T1 - Classification of mineral wool by spectroscopic methods N2 - Mineral wools from demolition projects are currently disposed of in landfills. To reintroduce them into the material cycle, it is essential (i) to distinguish between glass wool (GW) and rock wool (RW), (ii) to detect foreign substances, and (iii) to assess the period of production (before/after 2000) to identify “old”, potentially carcinogenic wool. Both X-ray and NIR spectroscopic methods are being developed for this purpose and handheld (portable) devices are being tested for field application. To this end, more than 160 mineral wool samples were collected and examined. Since no reference information on the “material” or “age” was available for many samples, we characterized the elemental composition of the mineral wool using wavelength dispersive X-ray fluorescence spectroscopy (WDXRF). For this purpose, pellets and melt tablets were evaluated using a spectrometer-integrated semi-quantitative approach (Omnian). The resulting mass fractions of SiO2, Al2O3, CaO, MgO, K2O, Na2O, Fe2O3, and TiO2 could be used to distinguish between GW and RW and, in the case of RW, also whether it was “old” or “new” wool according to VDI guideline 3492. In some cases, however, ambiguous results were obtained in the material classification. Therefore, a principal component analysis (PCA) was performed enabling the identification of possible outliers and subgroups. Since the classification of “old” and “new” rock wool based on VDI 3492 yielded many unclear results, with the help of partial least squares discriminant analysis (PLS-DA), the classification was significantly improved [1]. WDXRF spectroscopy delivers accurate results, however, the spectrometers are not mobile and require time demanding sample preparation (pellets, melt tablets). Therefore, it was examined whether useful results could be achieved with portable energy dispersive (EDXRF) spectrometers. For this purpose, a portable EDXRF spectrometer (pXRF) was calibrated based on the WDXRF results. In general, oxides of the lighter elements (MgO and Na2O) could not be analyzed with EDXRF. Although prediction of oxide contents in melt tablets was successful by this approach, no reliable results could be obtained when predicting the oxide content of natural mineral wools. Attempts to perform calibration based on natural wools also failed. However, PCA of EDXRF spectra in the “Light” range was able to distinguish between GW and RW, even with “real-world” samples from so-called Bigbags [2], in which mineral wool in Germany is collected in recycling centers. In addition to XRF, a previous study has already demonstrated that at least the distinction between GW and RW can be performed using near-infrared spectroscopy (NIR) [3]. For this reason, measurements were also carried out with a handheld NIR device (pNIR) in parallel with the pXRF investigations. Using PLS-DA, it was possible to classify RW and GW using the handheld device with a sensitivity and specificity of 95% for 38 test samples, including wool from big bags. pNIR also remains sensitive when it comes to determining non-metallic “foreign materials.” For example, materials such as brick, plaster, concrete, and organic fibers could be detected by SIMCA as “non-mineral” wool with a specificity of 92% for 19 tested interferents [2]. Questions regarding the detection of metallic impurities based on EDXRF measurements are the subject of ongoing investigations. T2 - Doctoral Seminar of the Working Group Chemometrics & Quality Assurance CY - Hamburg, Germany DA - 10.09.2025 KW - Mineral wool KW - X-ray fluorescence KW - Data analyis PY - 2025 AN - OPUS4-64077 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Golub, Tino Petar A1 - Meyer, Klas A1 - Paul, Andrea A1 - Kipphardt, Heinrich A1 - Tuma, Dirk T1 - Exploring the potential of a setup for combined quantification of hydrogen in natural gas – Raman and NMR spectroscopy N2 - An accurate measurement of the amount fraction of hydrogen in gas mixtures is mandatory for practical applications, requiring methods that are fast, continuous, robust, and cost-effective. This study compares the performance of Raman and benchtop NMR process spectroscopy for determining the hydrogen amount fraction in gas mixtures. A setup was designed to integrate both techniques, enabling measurements of the same sample. Tests were conducted with gravimetrically prepared gas mixtures of reference quality ranging from 1.20 cmol/mol to 85.83 cmol/mol of hydrogen. The results demonstrate that Raman spectroscopy provides superior performance, with a minimal root mean square error (RMSE) of 0.22 cmol/mol and excellent linearity. In contrast, benchtop NMR spectroscopy faced challenges, such as overlapping peaks and longer measurement times, resulting in a higher RMSE of 0.71 cmol/mol. Raman spectroscopy proves to be particularly well-suited for practical applications due to its high accuracy and linearity. Meanwhile, benchtop NMR spectroscopy holds potential for future enhancements through ongoing technological advances, such as higher magnetic field strengths. In summary, the results from our study indicate that Raman spectroscopy is already a serviceable method for precise hydrogen quantification, whereas benchtop NMR spectroscopy can be attributed potential for future applications. KW - Hydrogen amount fraction KW - Raman spectroscopy KW - NMR spectroscopy KW - Field applicability PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-610093 DO - https://doi.org/10.1016/j.saa.2024.125087 SN - 1386-1425 VL - 325 SP - 1 EP - 9 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-61009 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Altmann, Korinna A1 - Goedecke, Caroline A1 - Bannick, C.-G. A1 - Abusafia, A. A1 - Scheid, C. A1 - Steinmetz, H. A1 - Paul, Andrea A1 - Beleites, C. A1 - Braun, U. T1 - Identification of microplastic pathways within a typical European urban wastewater system N2 - In recent years, thermoextraction/desorption-gas chromatography/mass spectrometry (TED-GC/MS) has been developed as a rapid detection method for the determination of microplastics (MP) mass contents in numerous environmentally relevant matrices and, in particular, for the measurement of polymers in water samples without time-consuming sample preparation. The TED-GC/MS method was applied to investigate a typical European municipal wastewater system for possible MP masses. Such investigations are important in view of the recent revision of the Urban Wastewater Treatment Directive. Four different representative sampling sites were selected: greywater (domestic wastewater without toilet), combined sewer, and influent and effluent of a wastewater treatment plant (WWTP). All samples were collected by fractional filtration. Filtration was carried out over mesh sizes of 500, 100, 50, and in some cases, 5 µm. Polyethylene (PE), polypropylene (PP), and polystyrene (PS) were detected in all samples, with the PE fraction dominating in all cases. Styrene-butadiene rubber which serves as an indication of tire abrasion, was only found in the influent of the WWTP. The highest MP mass contents were found in the combined sewer, so MP can become a source of pollution during heavy rain events when the capacity limits of the effluent are reached, and the polluted effluent is released uncontrolled into the environment. Based on the studies, MP retention from the WWTP could be estimated to be approximately 96%. Few trends in polymer type or mass contents were detected within the different fractions of the samples or when comparing samples to each other. KW - Microplastics KW - Microplastic analysis KW - TED-GC/MS KW - Microplastic pathways KW - Mass contents PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568289 DO - https://doi.org/doi.org/10.1002/appl.202200078 SP - 1 EP - 10 PB - Wiley-VCH CY - Weinheim AN - OPUS4-56828 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neamtu, M. A1 - Nadejde, C. A1 - Brinza, L. A1 - Dragos, O. A1 - Gherghel, D. A1 - Paul, Andrea T1 - Iron phthalocyanine-sensitized magnetic catalysts for BPA photodegradation N2 - The catalytic behavior of iron phthalocyanine (FePc)-sensitized magnetic nanocatalysts was evaluated for their application in the oxidative treatment of Bisphenol A (BPA) under mild environmental conditions. Two types of FePc (Fe(II)Pc and Fe(III)Pc), which are highly photosensitive compounds, were immobilized on the surface of functionalized magnetite. The nanomaterials were characterized by high resolution transmission electron microscopy (HR-TEM), X-ray difraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA). The generation of singlet Oxygen by nanomaterials was also investigated. In the presence of UVA light exposure (365nm) and 15mM H2O2, the M@Fe(III)Pc photocatalyst gave the best results; for a catalyst concentration of 2.0gL −1, around 60% BPA was removed after 120min of reaction. These experimental conditions were further tested under natural solar light exposure, for which also M@Fe(III)Pc exhibited enhanced oxidative catalytic activity, being able to remove 83% of BPA in solution. The water samples were less cytotoxic after treatment, this being confrmed by the MCF-7 cell viability assay. KW - Photosensitization KW - magnetic nanocatalysts KW - BPA removal PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506368 DO - https://doi.org/10.1038/s41598-020-61980-6 VL - 10 IS - 1 SP - 5376 AN - OPUS4-50636 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Paul, Andrea T1 - Kombinierte Bestimmung von Wasserstoff in Gasgemischen mittels Raman- und NMR-Spektroskopie N2 - Vorgestellt wird die Nutzung von Online tauglichen Raman- und NMR-Spektrometern zur Quantifizierung des Wasserstoffmolanteils in gravimetrisch hergestellten Primärgasstandards unter Labor-Bedingungen. Es zeigte sich, dass Matrixeffekte insbesondere bei der Raman-Spektroskopie vernachlässigbar sind für die Quantifizierung von H2. Aufgrund der leichten Handhabbarkeit und der geringen Messunsicherheiten ergibt sich eine potenzielle Anwendung von Raman- und NMR-Spektroskopie unter Feldbedingungen als Online-Messeinheit im Bereich 5-100 cmol/mol Wasserstoff. T2 - 19. PAT Erfahrungsaustauschtreffen CY - Basel, Switzerland DA - 17.09.2024 KW - Raman KW - NMR KW - Wasserstoff PY - 2024 AN - OPUS4-62035 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhuang, Y. A1 - Spahr, S. A1 - Lutze, H.V. A1 - Reith, C.J. A1 - Hagemann, N. A1 - Paul, Andrea A1 - Haderlein, S.B. T1 - Persulfate activation by biochar and iron: Effect of chloride on formation of reactive species and transformation of N,N-diethyl-m-toluamide (DEET) N2 - Fenton-like processes using persulfate for oxidative water treatment and contaminant removal can be enhanced by the addition of redox-active biochar, which accelerates the reduction of Fe(III) to Fe(II) and increases the yield of reactive species that react with organic contaminants. However, available data on the formation of non-radical or radical species in the biochar/Fe(III)/persulfate system are inconsistent, which limits the evaluation of treatment efficiency and applicability in different water matrices. Based on competition kinetics calculations, we employed different scavengers and probe compounds to systematically evaluate the effect of chloride in presence of organic matter on the formation of major reactive species in the biochar/Fe(III)/persulfate system for the transformation of the model compound N,N‑diethyl-m-toluamide (DEET) at pH 2.5. We show that the transformation of methyl phenyl sulfoxide (PMSO) to methyl phenyl sulfone (PMSO2) cannot serve as a reliable indicator for Fe(IV), as previously suggested, because sulfate radicals also induce PMSO2 formation. Although the formation of Fe(IV) cannot be completely excluded, sulfate radicals were identified as the major reactive species in the biochar/Fe(III)/persulfate system in pure water. In the presence of dissolved organic matter, low chloride concentrations (0.1 mM) shifted the major reactive species likely to hydroxyl radicals. Higher chloride concentrations (1 mM), as present in a mining-impacted acidic surface water, resulted in the formation of another reactive species, possibly Cl2•−, and efficient DEET degradation. To tailor the application of this oxidation process, the water matrix must be considered as a decisive factor for reactive species formation and contaminant removal. KW - Water treatment KW - Organic contaminants KW - Fenton-like systems KW - Radicals KW - ESR PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608677 DO - https://doi.org/10.1016/j.watres.2024.122267 SN - 0043-1354 VL - 265 SP - 1 EP - 8 PB - Elsevier Ltd. AN - OPUS4-60867 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Paul, Andrea T1 - Potential of multivariate data analysis (MVA) in X-ray fluorescence analysis N2 - X-ray fluorescence spectrometry (XRF) is used, for example, in geochemistry, archaeology, materials science and agriculture to analyze the elemental composition of various samples [1]. Quantitative spectrum analysis typically applies methods such as fundamental parameters or intensity correction [1, 2]. However, there are also approaches to analyze XRF spectra using data-driven MVA approaches that are not based on a physical model. Principal component analysis (PCA) enables the visualization of data and the discovery of hidden relationships between analytical signals and sample parameters [1, 3]. Classification methods, e.g. PCA, cluster or discriminant analysis, can help to distinguish samples based on various complex integral features such as authenticity or origin of the sample [3]. MVA can also be used to correlate various external factors with elemental composition. In addition to classifying mineral wool into different material types based on characteristic oxides, PCA also enables the visualization of problem cases and supports the detection of possible outliers [4]. Multivariate regression methods such as partial least squares regression (PLSR) are a powerful tool for the quantitative analysis of spectra. In contrast to univariate analysis, in which only one characteristic is used as the basis for the regression, entire spectra or spectral ranges are analyzed here. It has been shown that the quantitative determination of C, H, N and O in polymers based on WDXRF spectra can be achieved by PLSR [5]. However, in the presence of complex matrix effects, the limitations of PLSR become clear, as was shown in a reference case (EDXRF spectra of steel and ore samples) [2]. Here, PLSR still outperformed the fundamental parameter approach, but proved to be less accurate than an intensity correction approach. Neural networks, which are better able to deal with nonlinear effects, are only an alternative if both a large number of calibration samples are available for adequate network training and a lot of time is available for network optimization. Despite limitations, it can be summarized that MVA, if used correctly, can contribute to increasing the informative value of XRF and to opening up new fields of application in areas of growing economic importance [1-5]. T2 - 12. PRORA Fachtagung Prozessnahe Röntgenanalytik CY - Berlin, Germany DA - 28.11.2024 KW - Chemometrics KW - Mineral wool KW - Data analysis KW - X-ray fluorescence PY - 2024 AN - OPUS4-62032 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -