Hochschule für Life Sciences FHNW

Dauerhafte URI für den Bereichhttps://irf.fhnw.ch/handle/11654/22

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Bereich: Suchergebnisse

Gerade angezeigt 1 - 4 von 4
  • Publikation
    Template-particle stabilized bicontinuous emulsion yielding controlled assembly of hierarchical high-flux filtration membranes
    (American Chemical Society, 2015) Hess, Samuel C.; Kohll, A. Xavier; Raso, Renzo; Schumacher, Christoph M.; Grass, Robert N.; Stark, Wendelin J.
    A novel solvent-evaporation-based process that exploits template-particle stabilized bicontinuous emulsions for the formation of previously unreached membrane morphologies is reported in this article. Porous membranes have a wide range of applications spanning from water filtration, pharmaceutical purification, and battery separators to scaffolds for tissue engineering. Different situations require different membrane morphologies including various pore sizes and pore gradients. However, most of the previously reported membrane preparation procedures are restricted to specific morphologies and morphology alterations require an extensive optimization process. The tertiary system presented in this article, which consists of a poly(ether sulfone)/dimethylacetamide (PES/DMAc) solution, glycerol, and ZnO-nanoparticles, allows simple and exact tuning of pore diameters ranging from sub-20 nm, up to 100 nm. At the same time, the pore size gradient is controlled from 0 up to 840%/μm yielding extreme asymmetry. In addition to structural analysis, water flux rates of over 5600 L m–2 h–1 are measured for membranes retaining 45 nm silica beads.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Publikation
    Nanoparticle-assisted, catalytic etching of carbon surfaces as a method to manufacture nanogrooves
    (American Chemical Society, 2012) Schumacher, Christoph M.; Koehler, Fabian M.; Rotzetter, Aline C. C.; Raso, Renzo; Stark, Wendelin J.
    A simple structuring method for graphitic structures based on the catalytic properties of cerium oxide nanoparticles under oxidizing conditions is presented. Highly oriented pyrolytic graphite chips were impregnated with well-dispersed ceria nanoparticles and then treated at elevated temperatures for several hours. Oxidation activities on the particle surface appeared as crystallographically independent traces that were formed on the graphite and provide a simple method to manufacture nanogrooves at large scale. By altering treatment durations and temperatures, the optimal conditions and activity parameters of the particles were determined. A systematic AFM evaluation allowed formulating of a mechanism of the etching process. The findings provide a simple procedure for the patterning of graphitic structures, formation of nanogrooves and thereby a basic tool for material science with respect to the manufacturing of atmospheric nanofilters and ion-selective membranes.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Publikation
    Coordination-driven monolayer-to-bilayer transition in two-dimensional metal–organic networks
    (American Chemical Society, 16.03.2021) Moradi, Mina; Lengweiler, Nadia; Housecroft, Catherine; Tulli, Ludovico; Stahlberg, Henning; Jung, Thomas; Shahgaldian, Patrick
    We report on monolayer-to-bilayer transitions in 2D metal–organic networks (MONs) from amphiphiles supported at the water–air interface. Functionalized calix[4]arenes are assembled through the coordination of selected transition metal ions to yield monomolecular 2D crystalline layers. In the presence of Ni(II) ions, interfacial self-assembly and coordination yields stable monolayers. Cu(II) promotes 2D coordination of a monolayer which is then diffusively reorganizing, nucleates, and grows a progressive amount of second layer islands. Atomic force microscopic data of these layers after transfer onto solid substrates reveal crystalline packing geometries with submolecular resolution as they are varying in function of the building blocks and the kinetics of the assembly. We assign this monolayer-to-bilayer transition to a diffusive reorganization of the initial monolayers owing to chemical vacancies of the predominant coordination motif formed by Cu2+ ions. Our results introduce a new dimension into the controlled monolayer-to-multilayer architecturing of 2D metal–organic networks.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Publikation
    Long-term field study on fate, transformation, and vertical transport of tetrabromobisphenol A in soil–plant systems
    (American Chemical Society, 21.03.2021) Corvini, Philippe; Songfeng, Wang; Xuan, Wu; Rong, Guo; Wang, Qilin; Guo, Hongyan; Sun, Feifei; Ji, Rong
    Soil contamination with tetrabromobisphenol A (TBBPA) has been an environmental concern for many years, but in situ studies of the fate and potential risk of TBBPA are lacking. In this study, we investigated the dissipation, metabolism, strong alkali-hydrolytic (SAH-TBBPA), and vertical movement of TBBPA in the field with and without rice-wheat rotation and reed growth for 1225 days. After 342 days of incubation, 21.3% of the TBBPA remained in the surface soil accompanied by obvious leaching to deeper soil layers in the first 92 days. By day 1225, TBBPA was nearly absent from the surface soil layer. A very low amount of SAH-TBBPA (2.31–3.43 mg/kg) was detected during the first 342 days of incubation. In the surface soil, five metabolites were identified that represented four interconnected pathways: oxidative skeletal cleavage, O-methylation, type II ipso-substitution, and reductive debromination. Both rice–wheat rotation and monocultural reed growth accelerated TBBPA removal in the field by stimulating the anaerobic debromination and aerobic O-methylation, especially the oxidative skeletal cleavage of TBBPA in the rhizosphere soil. Though far from comprehensive, our study investigated the natural attenuation and metabolism of TBBPA in situ and the influence by crops to estimate the environmental risk of TBBPA in a field scale.
    01A - Beitrag in wissenschaftlicher Zeitschrift