Martine Meireles | Université Paul Sabatier de Toulouse (original) (raw)
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Papers by Martine Meireles
Membrane Processes in Separation and Purification, 1994
Journal of Membrane Science, 1996
Atomic force and scanning tunneling microscopes have been used to investigate the surface of poly... more Atomic force and scanning tunneling microscopes have been used to investigate the surface of polymeric ultrafiltration and microfiltration membranes.
Comment opérer une séparation à l'aide d'un procédé à membranes en maîtrisant le colmatage ?
A characterisation method giving the average radius and the geometric standard deviation is used ... more A characterisation method giving the average radius and the geometric standard deviation is used to study the influence of fouling on the apparent porous structure of ultrafiltration membranes. A way of estimating the pore density is proposed. Polysulphone membranes of different molar weight cut-offs and globular proteins of different size are used. It is shown how the effects of fouling on solvent flux and on retention depend on the size of both pores and foulant molecules. The results suggest that fouling involves two mechanisms: internal pore fouling and build-up of a layer depending on both porous structure and solute size.
Understanding the mechanisms that control the filtration of a complex medium is a major challenge... more Understanding the mechanisms that control the filtration of a complex medium is a major challenge for the development of membrane-based processes in bio-industries, agro-industries or sludge treatment, where the complexity of the fluids is seen in terms of composition (liquid-liquid or liquid-solid mixtures), or physico-chemical characteristics (rheology, stability, etc.). This complexity is likely to induce different material organisations within the fluid depending on concentration and hydrodynamics fields.
This study reports a numerical approach for modeling the hydraulic resistance of a filter cake of... more This study reports a numerical approach for modeling the hydraulic resistance of a filter cake of deformable cells. First, a mechanical and osmotic model that describes the volume fraction of solids in a bed of yeast cells as a function of the compressive pressure it experiences is presented. The effects of pressure on the compressibility of yeast cells beds were further investigated both by filtration experiments and by centrifugal experiments based on the multiple speed equilibrium sediment height technique. When comparing the latter measurements with compression model calculations, we observed that the method based on centrifugal experiments suffers from rapid relaxation of the compressed bed. Concerning the filtration experiments, 2 specific resistance of well defined bed of cells were calculated by a combination of the compression model with a formulation for hydraulic resistivity developed using the Lattice Boltzmann method. We further explain the experimental values observed for the hydraulic resistance of cell beds, assuming that the first layer of cells in contact with the membrane partially blocks the membrane area open to flow. In such a case, the blocked area seems to be a constant fraction of the normal cell-cell contact area.
In this paper, we report experiments where the capture of micron-sized particles is observed in a... more In this paper, we report experiments where the capture of micron-sized particles is observed in a poly-dimethylsiloxane (PDMS) microfluidic device. The filtering part of the device consists of an array of parallel micro-channels (width: 20 microns, height: 50 microns). Direct observations of the filtering part by video-microscopy allow to investigate the way the fouling of the microchannels by the particles is taking place. The experimental results underline the important role played by the PDMS "conditioning" on the way particles are captured during filtration. When a filtration experiment is performed after a rinse of the PDMS microsystem with ultrapure water, the particles first form arches at the microchannels entrance, then leading to the growth of a filtration cake. When a filtration experiment is performed after a rinse with a saline solution (water with KCl at 10 -1 M), the particles are captured on the walls between the microchannels, then leading to the progressive formation of dendrites. As the experiments are performed at a constant flow rate, an increase in the pressure drop across the microsystem is observed because of clogging. The formation of dendrites induces a smaller increase in pressure than the formation of a cake. An elution of the PDMS with the saline solution may be the reason why these different fouling behaviors are observed.
Membrane Processes in Separation and Purification, 1994
Journal of Membrane Science, 1996
Atomic force and scanning tunneling microscopes have been used to investigate the surface of poly... more Atomic force and scanning tunneling microscopes have been used to investigate the surface of polymeric ultrafiltration and microfiltration membranes.
Comment opérer une séparation à l'aide d'un procédé à membranes en maîtrisant le colmatage ?
A characterisation method giving the average radius and the geometric standard deviation is used ... more A characterisation method giving the average radius and the geometric standard deviation is used to study the influence of fouling on the apparent porous structure of ultrafiltration membranes. A way of estimating the pore density is proposed. Polysulphone membranes of different molar weight cut-offs and globular proteins of different size are used. It is shown how the effects of fouling on solvent flux and on retention depend on the size of both pores and foulant molecules. The results suggest that fouling involves two mechanisms: internal pore fouling and build-up of a layer depending on both porous structure and solute size.
Understanding the mechanisms that control the filtration of a complex medium is a major challenge... more Understanding the mechanisms that control the filtration of a complex medium is a major challenge for the development of membrane-based processes in bio-industries, agro-industries or sludge treatment, where the complexity of the fluids is seen in terms of composition (liquid-liquid or liquid-solid mixtures), or physico-chemical characteristics (rheology, stability, etc.). This complexity is likely to induce different material organisations within the fluid depending on concentration and hydrodynamics fields.
This study reports a numerical approach for modeling the hydraulic resistance of a filter cake of... more This study reports a numerical approach for modeling the hydraulic resistance of a filter cake of deformable cells. First, a mechanical and osmotic model that describes the volume fraction of solids in a bed of yeast cells as a function of the compressive pressure it experiences is presented. The effects of pressure on the compressibility of yeast cells beds were further investigated both by filtration experiments and by centrifugal experiments based on the multiple speed equilibrium sediment height technique. When comparing the latter measurements with compression model calculations, we observed that the method based on centrifugal experiments suffers from rapid relaxation of the compressed bed. Concerning the filtration experiments, 2 specific resistance of well defined bed of cells were calculated by a combination of the compression model with a formulation for hydraulic resistivity developed using the Lattice Boltzmann method. We further explain the experimental values observed for the hydraulic resistance of cell beds, assuming that the first layer of cells in contact with the membrane partially blocks the membrane area open to flow. In such a case, the blocked area seems to be a constant fraction of the normal cell-cell contact area.
In this paper, we report experiments where the capture of micron-sized particles is observed in a... more In this paper, we report experiments where the capture of micron-sized particles is observed in a poly-dimethylsiloxane (PDMS) microfluidic device. The filtering part of the device consists of an array of parallel micro-channels (width: 20 microns, height: 50 microns). Direct observations of the filtering part by video-microscopy allow to investigate the way the fouling of the microchannels by the particles is taking place. The experimental results underline the important role played by the PDMS "conditioning" on the way particles are captured during filtration. When a filtration experiment is performed after a rinse of the PDMS microsystem with ultrapure water, the particles first form arches at the microchannels entrance, then leading to the growth of a filtration cake. When a filtration experiment is performed after a rinse with a saline solution (water with KCl at 10 -1 M), the particles are captured on the walls between the microchannels, then leading to the progressive formation of dendrites. As the experiments are performed at a constant flow rate, an increase in the pressure drop across the microsystem is observed because of clogging. The formation of dendrites induces a smaller increase in pressure than the formation of a cake. An elution of the PDMS with the saline solution may be the reason why these different fouling behaviors are observed.