Hedwig, Sebastian

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Hedwig
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Sebastian
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Hedwig, Sebastian

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Gerade angezeigt 1 - 5 von 5
  • Publikation
    From trace to pure. Pilot-scale scandium recovery from TiO2 acid waste
    (American Chemical Society, 06.04.2023) Hedwig, Sebastian; Yagmurlu, Bengi; Peters, Edward Michael; Misev, Victor; Hengevoss, Dirk; Dittrich, Carsten; Forsberg, Kerstin; Constable, Edwin C.; Lenz, Markus [in: ACS Sustainable Chemistry & Engineering]
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Publikation
    Ecotoxicity attenuation by acid-resistant nanofiltration in scandium recovery from TiO2 production waste
    (Elsevier, 2023) Fekete-Kertész, Ildikó; Stirling, Tamás; Vaszita, Emese; Berkl, Zsófia; Farkas, Éva; Hedwig, Sebastian; Remmen, Kirsten; Lenz, Markus; Molnár, Mónika; Feigl, Viktória [in: Heliyon]
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Publikation
    Nanofiltration-enhanced solvent extraction of scandium from TiO acid waste
    (American Chemical Society, 27.04.2022) Yagmurlu, Bengi; Huang, Danyu; von Arx, Oliver; Dittrich, Carsten; Constable, Edwin; Friedrich, Bernd; Hedwig, Sebastian; Lenz, Markus [in: ACS Sustainable Chemistry & Engineering]
    Scandium is a critical raw material with a technological potential to reduce transportation costs and CO2 emissions. However, global supply and market adoption are crucially impaired by the lack of high-grade Sc ores and recovery strategies. A tandem nanofiltration solvent extraction route is demonstrated to enable effective Sc recovery from real-world acid waste from the chloride TiO2 production route. The process involving several filtration stages, solvent extraction, and precipitation was optimized, ultimately producing >97% pure (NH4)3ScF6.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Publikation
    Recovery of scandium from acidic waste solutions by means of polymer inclusion membranes
    (Elsevier, 2022) Hedwig, Sebastian; Kraus, Manuel; Amrein, Meret; Stiehm, Johannes; Constable, Edwin C.; Lenz, Markus [in: Hydrometallurgy]
    Scandium is a raw material with properties that promise considerable potential for application in alloys to enable aviation fuel savings and as dopants for use in sustainable energy production using solid oxide fuel cells. Despite these attractive properties, scandium is rarely used due to its scarcity and unreliable supply. Therefore, new strategies for scandium recovery are of economic priority. In this study, polymer inclusion membranes (PIMs) consisting of PVDF-HFP, 2-NPOE and DEHPA, were optimised for selective scandium separation from real TiO2 production waste. With the optimised system, >60% of the scandium was recovered with high selectivity, resulting in scandium mole fraction at more than two orders of magnitude higher in the receiving phase than in the original waste. This suggests PIMs may be an effective way to recover scandium from bulk waste, thus easing the scarcity and insecurity that currently limit its bulk application.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Publikation
    Sulfur amino acid status controls selenium methylation in pseudomonas tolaasii. Identification of a novel metabolite from promiscuous enzyme reactions
    (American Society for Microbiology, 26.05.2021) Liu, Ying; Hedwig, Sebastian; Schäffer, Andreas; Lenz, Markus; Martinez, Mathieu [in: Applied and Environmental Microbiology]
    Selenium (Se) deficiency affects many millions of people worldwide, and the volatilization of methylated Se species to the atmosphere may prevent Se from entering the food chain. Despite the extent of Se deficiency, little is known about fluxes in volatile Se species and their temporal and spatial variation in the environment, giving rise to uncertainty in atmospheric transport models. To systematically determine fluxes, one can rely on laboratory microcosm experiments to quantify Se volatilization in different conditions. Here, it is demonstrated that the sulfur (S) status of bacteria crucially determines the amount of Se volatilized. Solid-phase microextraction gas chromatography mass spectrometry showed that Pseudomonas tolaasii efficiently and rapidly (92% in 18 h) volatilized Se to dimethyl diselenide and dimethyl selenyl sulfide through promiscuous enzymatic reactions with the S metabolism. However, when the cells were supplemented with cystine (but not methionine), a major proportion of the Se (∼48%) was channeled to thus-far-unknown, nonvolatile Se compounds at the expense of the previously formed dimethyl diselenide and dimethyl selenyl sulfide (accounting for <4% of total Se). Ion chromatography and solid-phase extraction were used to isolate unknowns, and electrospray ionization ion trap mass spectrometry, electrospray ionization quadrupole time-of-flight mass spectrometry, and microprobe nuclear magnetic resonance spectrometry were used to identify the major unknown as a novel Se metabolite, 2-hydroxy-3-(methylselanyl)propanoic acid. Environmental S concentrations often exceed Se concentrations by orders of magnitude. This suggests that in fact S status may be a major control of selenium fluxes to the atmosphere. IMPORTANCE Volatilization from soil to the atmosphere is a major driver for Se deficiency. “Bottom-up” models for atmospheric Se transport are based on laboratory experiments quantifying volatile Se compounds. The high Se and low S concentrations in such studies poorly represent the environment. Here, we show that S amino acid status has in fact a decisive effect on the production of volatile Se species in Pseudomonas tolaasii. When the strain was supplemented with S amino acids, a major proportion of the Se was channeled to thus-far-unknown, nonvolatile Se compounds at the expense of volatile compounds. This hierarchical control of the microbial S amino acid status on Se cycling has been thus far neglected. Understanding these interactions—if they occur in the environment—will help to improve atmospheric Se models and thus predict drivers of Se deficiency.
    01A - Beitrag in wissenschaftlicher Zeitschrift