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Ergebnisse nach Hochschule und Institut
Publikation Rapid sequestration of perovskite solar cell-derived lead in soil(Elsevier, 08/2022) Schmidt, Felix; Ledermann, Luca; Schäffer, Andreas; Snaith, Henry J.; Lenz, MarkusEfficient and stable perovskite solar cells rely on the use of Pb species potentially challenging the technologies’ commercialisation. In this study, the fate of Pb derived from two common perovskite precursors is compared to cationic lead in soil-water microcosm experiments under various biogeochemical conditions. The rapid and efficient removal of Pb from the aqueous phase is demonstrated by inductively coupled plasma mass spectrometry. Sequential soil extraction results reveal that a substantial amount of Pb is associated with immobile fractions, whereas a minor proportion of Pb may become available again in the long term, when oxygen is depleted (e.g. during water logging). X-ray absorption spectroscopy results reveal that the sorption of Pb on mineral phases represents the most likely sequestration mechanism. The obtained results suggest that the availability of leached Pb from perovskite solar cells is naturally limited in soils and that its adverse effects on soil biota are possibly negligible in oxic soils. All three Pb sources used behaved very similar in the experiments, wherefore we conclude that perovskite derived Pb will have a similar fate compared to cationic Pb, so that established risk assessment considerations for Pb remain legitimate.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Production of superparamagnetic nanobiocatalysts for green chemistry applications(Springer, 23.04.2016) Gasser, Christoph; Ammann, Erik; Schäffer, Andreas; Shahgaldian, Patrick; Corvini, PhilippeImmobilization of enzymes on solid supports is a convenient method for increasing enzymatic stability and enabling enzyme reuse. In the present work, a sorption-assisted surface conjugation method was developed and optimized to immobilize enzymes on the surface of superparamagnetic nanoparticles. An oxidative enzyme, i.e., laccase from Trametes versicolor was used as model enzyme. The immobilization method consists of the production of superparamagnetic nanoparticles by co-precipitation of FeCl2 and FeCl3. Subsequently, the particle surface is modified with an organosilane containing an amino group. Next, the enzymes are adsorbed on the particle surface before a cross-linking agent, i.e., glutaraldehyde is added which links the amino groups on the particle surface with the amino groups of the enzymes and leads to internal cross-linking of the enzymes as well. The method was optimized using response surface methodology regarding optimal enzyme and glutaraldehyde amounts, pH, and reaction times. Results allowed formulation of biocatalysts having high specific enzymatic activity and improved stability. The biocatalysts showed considerably higher stability compared with the dissolved enzymes over a pH range from 3 to 9 and in the presence of several chemical denaturants. To demonstrate the reusability of the immobilized enzymes, they were applied as catalysts for the production of a phenoxazinone dye. Virtually, 100 % of the precursor was transformed to the dye in each of the ten conducted reaction cycles while on average 84.5 % of the enzymatic activity present at the beginning of a reaction cycle was retained after each cycle highlighting the considerable potential of superparamagnetic biocatalysts for application in industrial processes.01A - Beitrag in wissenschaftlicher Zeitschrift