Université de Fribourg

Colloidal transformations in ms2 virus particles: driven by ph, influenced by natural organic matter

Watts, Samuel ; Julian, Timothy R. ; Maniura-Weber, Katharina ; Graule, Thomas ; Salentinig, Stefan

In: ACS Nano, 2020, vol. 14, no. 2, p. 1879–1887

Enteric viruses, such as enterovirus, norovirus, and rotavirus, are among the leading causes of disease outbreaks due to contaminated drinking and recreational water. Viruses are difficult to remove from water through filtration based on physical size exclusion—for example by gravity-driven filters—due to their nanoscale size. To understand virus removal in drinking water treatment ...

Université de Fribourg

Manufacturing of tubular dead-end membranes by continuous thermoplastic extrusion

Salehi, Mehdi ; Pfaff, Ewald M. ; Kaletsch, Anke ; Graule, Thomas ; Clemens, Frank ; Grobéty, Bernard

In: International Journal of Applied Ceramic Technology, 2015, vol. 12, p. E13–E18

Dense and gastight dead-end tubular Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) membranes were fabricated by thermoplastic extrusion. Optimal feedstocks for the extrusion of dead-end tubular structures were obtained for a feedstock consisting of 89.83 wt% BSCF powder, 5.63 wt% ethylene vinyl acetate (EVA), 3.56 wt% paraffin wax (PW), and 0.98 wt%...

Université de Fribourg

Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) feedstock development and optimization for thermoplastic forming of thin planar and tubular oxygen separation membranes

Salehi, Mehdi ; Clemens, Frank ; Pfaff, Ewald M. ; Junior, Roberto M. ; Bergmann, Carlos P. ; Diethelm, Stefan ; Neururer, Christoph ; Graule, Thomas ; Grobéty, Bernard

In: Journal of Membrane Science, 2013, p. -

This paper presents the processing steps for producing thin planar and tubular oxygen separation membranes by thermoplastic forming of Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) with polystyrene (PS) and stearic acid (SA) as binder. The influence of powder content on the shape stability of thin membranes (tubular and planar structures)...

Université de Fribourg

Kinetic analysis of the polymer burnout in ceramic thermoplastic processing of the YSZ thin electrolyte structures using model free method

Salehi, Mehdi ; Clemens, Frank ; Graule, Thomas ; Grobéty, Bernard

In: Applied Energy, 2012, vol. 95, p. 147-155

Polymeric binder burnout during thermoplastic processing of yttria stabilized zirconia (YSZ) ceramics were analyzed using thermogravimetric analysis (TGA). The debinding kinetics of the stearic acid/polystyrene binder have been described using model free methods and compared with the decomposition rate of the pure polymers. The apparent activation energy Eα as a function of...

Université de Fribourg

A case study of the effect of grain size on the oxygen permeation flux of BSCF disk-shaped membrane fabricated by thermoplastic processing

Salehi, Mehdi ; Clemens, Frank ; Pfaff, Ewald M. ; Diethelm, Stefan ; Leach, Colin ; Graule, Thomas ; Grobéty, Bernard

In: Journal of Membrane Science, 2011, vol. 382, no. 1-2, p. 186-193

Oxygen permeability measurements of Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) disk shaped membranes fabricated by thermoplastic processing and sintered at different temperatures (1000–1100 °C), showed no influence of the grain size on the oxygen permeation fluxes. To further investigations, Electron Backscattered Diffraction (EBSD) and...

Université de Fribourg

XRCT characterisation of Ti particles inside porous Al₂O₃

Vasić, Srdan ; Grobéty, Bernard ; Kuebler, Jakob ; Graule, Thomas ; Baumgartner, Lukas

In: Materials Characterization, 2010, vol. 61, no. 6, p. 653-660

Computed X-ray tomography was used to characterise distribution and sphericity of Ti granules within highly porous (> 35%) Al₂O₃ powder compacts, as they are key parameters for a successful infiltration by Fe-based alloys. Setting of reconstruction constraints, image editing as well as data processing are the most challenging parts of computed X-ray tomography and principal sources of errors...

Université de Fribourg

Activation mechanism and infiltration kinetic for pressureless melt infiltration of Ti activated Al₂O₃ preforms by high melting alloy

Vasi, Srdan ; Grobéty, Bernard ; Kuebler, Jakob ; Graule, Thomas

In: Advanced Engineering Materials, 2009, vol. 11, no. 8, p. 659 - 666

The infiltration mechanism of X3CrNi13-4 in titanium activated porous alumina preforms has been studied. Investigations revealed isolated steel-covered titanium particles beyond the infiltration front. The only transport path possible for the steel to form such wetted islands is through the gas phase. Supersaturation due to the mixing of the steel gas phase with the titanium rich gas phase...