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Saal, Leon

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  • Veröffentlichung
    Automated scraping and analyses of drinking water quality data
    (2023) Ruhl, Aki Sebastian; Saal, Leon
    Drinking water quality data, though regularly monitored, is not available in Germany as national overview, but only decentralized from the water suppliers. On the national level, only the number of limit exceedances are reported. An overview on drinking water qualities as complete as possible however is necessary to assess and develop regulations and helpful for authorities, political decision makers, the public and the scientific community. Due to the fragmented nature of the data sources, web-scraping was used in the present study to mitigate aforementioned challenges and knowledge gaps. Data from 502 water supply areas were compiled and further evaluated. The extent and form of reported values varied strongly, as did the availability of data for the different water supply areas. The results show, that the scraped values were not close to but well below associated legal limits or guidance values. For organic parameters, the reported values were mostly below the respective limits of quantification. However, further developments are needed to cover more water supply areas in Germany and internationally. © 2023 The Authors
  • Veröffentlichung
    Characterization of activated carbons for water treatment using TGA-FTIR for analysis of oxygen-containing functional groups
    (2022) Dittmann, Daniel; Zietzschmann, Frederik; Ruhl, Aki Sebastian; Schumann, Pia; Saal, Leon; Braun, Ulrike
    Water treatment with activated carbon (AC) is an established method for the removal of organic micropollutants and natural organic matter. However, it is not yet possible to predict the removal of individual pollutants. An appropriate material characterization, matching adsorption processes in water, might be the missing piece in the puzzle. To this end, this study examined 25 different commercially available ACs to evaluate their material properties. Frequently reported analyses, including N2 adsorption/desorption, CHNS(O), point of zero charge (PZC) analysis, and X-ray photoelectron spectroscopy (XPS) were conducted on a selected subset of powdered ACs. Inorganic elements examined using X-ray fluorescence (XRF) and X-ray iffraction spectroscopy (XRD) revealed that relative elemental contents were distinctive to the individual AC's raw material and activation procedure. This study also is the first to use thermogravimetric analysis (TGA) coupled to Fourier-transform infrared spectroscopy (FTIR) to conduct quantitative analyses of functional surface oxygen groups (SOGs: carboxylic acid, anhydride, lactone, phenol, carbonyl, and pyrone groups) on such a large number of ACs. The comparably economical TGA provides a surrogate for the PZC, the oxygen and carbon content, as well as mass loss profiles that depict the AC's chemistry. Furthermore, we found that SOG contents determined by TGA-FTIR covered a wide individual range and depended on the raw material of the AC. Surface chemistry might therefore provide an indication of the suitability of a particular AC for a variety of target substances in different target waters. TGA and TGA-FTIR can help practitioners to control AC use in waterworks or wastewater treatment plants.