The Experts below are selected from a list of 2199 Experts worldwide ranked by ideXlab platform

Christophe Ybert - One of the best experts on this subject based on the ideXlab platform.

  • Flow-induced shift of the Donnan Equilibrium for ultra-sensitive mass transport measurement through a single nanochannel.
    The Journal of chemical physics, 2019
    Co-Authors: Simon Gravelle, Christophe Ybert
    Abstract:

    Despite mass flow being arguably the most elementary transport associated with nanofluidics, its measurement still constitutes a significant bottleneck for the development of this promising field. Here, we investigate how a liquid flow perturbs the ubiquitous enrichment-or depletion-of a solute inside a single nanochannel. Using fluorescence correlation spectroscopy to access the local solute concentration, we demonstrate that the initial enrichment-the so-called Donnan Equilibrium-is depleted under flow, thus revealing the underlying mass transport. Combining theoretical and numerical calculations beyond the classical 1D treatment of nanochannels, we rationalize quantitatively our observations and demonstrate unprecedented flow rate sensitivity. Because the present mass transport investigations are based on generic effects, we believe that they can develop into a versatile approach for nanofluidics.

  • Flow-Induced Shift of the Donnan Equilibrium for Ultra-Sensitive Mass Transport Measurement Through a Single Nanochannel
    Journal of Chemical Physics, 2019
    Co-Authors: Simon Gravelle, Christophe Ybert
    Abstract:

    Despite mass flow is arguably the most elementary transport associated to nanofluidics, its measurement still constitutes a significant bottleneck for the development of this promising field. Here, we investigate how a liquid flow perturbs the ubiquitous enrichment-or depletion-of a solute inside a single nanochannel. Using Fluorescence Correlation Spectroscopy to access the local solute concentration, we demonstrate that the initial enrichment-the so-called Donnan Equilibrium-is depleted under flow thus revealing the underlying mass transport. Combining theoretical and numerical calculations beyond the classical 1D treatments of nanochannels, we rationalize quantitatively our observations and demonstrate unprecedented flow rate sensitivity. Because the present mass transport investigations are based on generic effects, we believe they can develop into a versatile approach for nanofluidics.

Simon Gravelle - One of the best experts on this subject based on the ideXlab platform.

  • Flow-induced shift of the Donnan Equilibrium for ultra-sensitive mass transport measurement through a single nanochannel.
    The Journal of chemical physics, 2019
    Co-Authors: Simon Gravelle, Christophe Ybert
    Abstract:

    Despite mass flow being arguably the most elementary transport associated with nanofluidics, its measurement still constitutes a significant bottleneck for the development of this promising field. Here, we investigate how a liquid flow perturbs the ubiquitous enrichment-or depletion-of a solute inside a single nanochannel. Using fluorescence correlation spectroscopy to access the local solute concentration, we demonstrate that the initial enrichment-the so-called Donnan Equilibrium-is depleted under flow, thus revealing the underlying mass transport. Combining theoretical and numerical calculations beyond the classical 1D treatment of nanochannels, we rationalize quantitatively our observations and demonstrate unprecedented flow rate sensitivity. Because the present mass transport investigations are based on generic effects, we believe that they can develop into a versatile approach for nanofluidics.

  • Flow-Induced Shift of the Donnan Equilibrium for Ultra-Sensitive Mass Transport Measurement Through a Single Nanochannel
    Journal of Chemical Physics, 2019
    Co-Authors: Simon Gravelle, Christophe Ybert
    Abstract:

    Despite mass flow is arguably the most elementary transport associated to nanofluidics, its measurement still constitutes a significant bottleneck for the development of this promising field. Here, we investigate how a liquid flow perturbs the ubiquitous enrichment-or depletion-of a solute inside a single nanochannel. Using Fluorescence Correlation Spectroscopy to access the local solute concentration, we demonstrate that the initial enrichment-the so-called Donnan Equilibrium-is depleted under flow thus revealing the underlying mass transport. Combining theoretical and numerical calculations beyond the classical 1D treatments of nanochannels, we rationalize quantitatively our observations and demonstrate unprecedented flow rate sensitivity. Because the present mass transport investigations are based on generic effects, we believe they can develop into a versatile approach for nanofluidics.

Philippe Leroy - One of the best experts on this subject based on the ideXlab platform.

  • Diffusion of ionic tracers in the Callovo-Oxfordian clay-rock using the Donnan Equilibrium model and the formation factor
    Geochimica et Cosmochimica Acta, 2009
    Co-Authors: D. Jougnot, A. Revil, Philippe Leroy
    Abstract:

    The transient diffusion of cationic and anionic tracers through clay-rocks is usually modeled with parameters like porosity, tortuosity (and/or constrictivity), sorption coefficients, and anionic exclusion. Recently, a new pore scale model has been developed by Revil and Linde [Revil A. and Linde N. (2006) Chemico-electromechanical coupling in microporous media. J. Colloid Interface Sci. 302, 682–694]. This model is based on a volume-averaging approach of the Nernst–Planck equation. The influence of the electrical diffuse layer is accounted for by a generalized Donnan Equilibrium model through the whole connected pore space that is valid for a multicomponent electrolyte. This new model can be used to determine the composition of the pore water of the Callovo-Oxfordian clay-rock, the osmotic efficiency of bentonite as a function of salinity, the osmotic pressure, and the streaming potential coupling coefficient of clay-rocks. This pore scale model is used here to model the transient diffusion of ionic tracers ( 22Na+, 36Cl

  • Diffusion of ionic tracers in the Callovo-Oxfordian clay-rock using the Donnan Equilibrium model and the formation factor.
    Geochimica et Cosmochimica Acta, 2009
    Co-Authors: D. Jougnot, A. Revil, Philippe Leroy
    Abstract:

    Abstract The transient diffusion of cationic and anionic tracers through clay-rocks is usually modeled with parameters like porosity, tortuosity (and/or constrictivity), sorption coefficients, and anionic exclusion. Recently, a new pore scale model has been developed by Revil and Linde [Revil A. and Linde N. (2006) Chemico-electromechanical coupling in microporous media. J. Colloid Interface Sci. 302, 682–694]. This model is based on a volume-averaging approach of the Nernst–Planck equation. The influence of the electrical diffuse layer is accounted for by a generalized Donnan Equilibrium model through the whole connected pore space that is valid for a multicomponent electrolyte. This new model can be used to determine the composition of the pore water of the Callovo-Oxfordian clay-rock, the osmotic efficiency of bentonite as a function of salinity, the osmotic pressure, and the streaming potential coupling coefficient of clay-rocks. This pore scale model is used here to model the transient diffusion of ionic tracers (22Na+, 36Cl−, and 35 SO 4 2 - ) through the Callovo-Oxfordian clay-rock. Speciation of SO 4 2 - shows that ∼1/3 of the SO4 is tied-up in different complexes. Some of these complexes are neutral and are therefore only influence by the tortuosity of the pore space. Using experimental data from the literature, we show that all the parameters required to model the flux of ionic tracers (especially the mean electrical potential of the pore space and the formation factor) are in agreement with independent evaluations of these parameters using the osmotic pressure determined from in situ pressure measurements and HTO diffusion experiments.

P M Biesheuvel - One of the best experts on this subject based on the ideXlab platform.

  • validity of the boltzmann equation to describe Donnan Equilibrium at the membrane solution interface
    Journal of Membrane Science, 2013
    Co-Authors: A H Galama, J W Post, M Cohen A Stuart, P M Biesheuvel
    Abstract:

    Abstract To describe Donnan Equilibrium at the membrane–solution interface, the simplest approach uses the classical Boltzmann equation, based on a mean-field description of ions as ideal point charges, in combination with the assumption of fully overlapped electrical double layers in the membrane pores. We test the Boltzmann equation by measurement of the Equilibrium counterion and co-ion concentration in densely charged membranes equilibrated with various NaCl solutions (0.01–3 M). To obtain a good fit of data it was found necessary to express the membrane charge and ion concentration per volume of aqueous solution phase in the membrane, and to include a volume-exclusion term in the Boltzmann relation. A discrepancy between theory and experiment data is found at low external NaCl concentrations. Similar deviations from the Donnan model have been reported for over half a century, but do not yet have a convincing explanation. Agreement between experiment data and theory at low external NaCl concentrations is obtained when we model the desorption experiment taking into account the role of H + and OH − ions in closing the charge balance, and postulating the presence in the membrane of a tiny amount of fixed groups with a charge opposite to overall fixed membrane charge.

  • Validity of the Boltzmann equation to describe Donnan Equilibrium at the membrane–solution interface
    Journal of Membrane Science, 2013
    Co-Authors: A H Galama, J W Post, M.a. Cohen Stuart, P M Biesheuvel
    Abstract:

    Abstract To describe Donnan Equilibrium at the membrane–solution interface, the simplest approach uses the classical Boltzmann equation, based on a mean-field description of ions as ideal point charges, in combination with the assumption of fully overlapped electrical double layers in the membrane pores. We test the Boltzmann equation by measurement of the Equilibrium counterion and co-ion concentration in densely charged membranes equilibrated with various NaCl solutions (0.01–3 M). To obtain a good fit of data it was found necessary to express the membrane charge and ion concentration per volume of aqueous solution phase in the membrane, and to include a volume-exclusion term in the Boltzmann relation. A discrepancy between theory and experiment data is found at low external NaCl concentrations. Similar deviations from the Donnan model have been reported for over half a century, but do not yet have a convincing explanation. Agreement between experiment data and theory at low external NaCl concentrations is obtained when we model the desorption experiment taking into account the role of H + and OH − ions in closing the charge balance, and postulating the presence in the membrane of a tiny amount of fixed groups with a charge opposite to overall fixed membrane charge.

D. Jougnot - One of the best experts on this subject based on the ideXlab platform.

  • Diffusion of ionic tracers in the Callovo-Oxfordian clay-rock using the Donnan Equilibrium model and the formation factor
    Geochimica et Cosmochimica Acta, 2009
    Co-Authors: D. Jougnot, A. Revil, Philippe Leroy
    Abstract:

    The transient diffusion of cationic and anionic tracers through clay-rocks is usually modeled with parameters like porosity, tortuosity (and/or constrictivity), sorption coefficients, and anionic exclusion. Recently, a new pore scale model has been developed by Revil and Linde [Revil A. and Linde N. (2006) Chemico-electromechanical coupling in microporous media. J. Colloid Interface Sci. 302, 682–694]. This model is based on a volume-averaging approach of the Nernst–Planck equation. The influence of the electrical diffuse layer is accounted for by a generalized Donnan Equilibrium model through the whole connected pore space that is valid for a multicomponent electrolyte. This new model can be used to determine the composition of the pore water of the Callovo-Oxfordian clay-rock, the osmotic efficiency of bentonite as a function of salinity, the osmotic pressure, and the streaming potential coupling coefficient of clay-rocks. This pore scale model is used here to model the transient diffusion of ionic tracers ( 22Na+, 36Cl

  • Diffusion of ionic tracers in the Callovo-Oxfordian clay-rock using the Donnan Equilibrium model and the formation factor.
    Geochimica et Cosmochimica Acta, 2009
    Co-Authors: D. Jougnot, A. Revil, Philippe Leroy
    Abstract:

    Abstract The transient diffusion of cationic and anionic tracers through clay-rocks is usually modeled with parameters like porosity, tortuosity (and/or constrictivity), sorption coefficients, and anionic exclusion. Recently, a new pore scale model has been developed by Revil and Linde [Revil A. and Linde N. (2006) Chemico-electromechanical coupling in microporous media. J. Colloid Interface Sci. 302, 682–694]. This model is based on a volume-averaging approach of the Nernst–Planck equation. The influence of the electrical diffuse layer is accounted for by a generalized Donnan Equilibrium model through the whole connected pore space that is valid for a multicomponent electrolyte. This new model can be used to determine the composition of the pore water of the Callovo-Oxfordian clay-rock, the osmotic efficiency of bentonite as a function of salinity, the osmotic pressure, and the streaming potential coupling coefficient of clay-rocks. This pore scale model is used here to model the transient diffusion of ionic tracers (22Na+, 36Cl−, and 35 SO 4 2 - ) through the Callovo-Oxfordian clay-rock. Speciation of SO 4 2 - shows that ∼1/3 of the SO4 is tied-up in different complexes. Some of these complexes are neutral and are therefore only influence by the tortuosity of the pore space. Using experimental data from the literature, we show that all the parameters required to model the flux of ionic tracers (especially the mean electrical potential of the pore space and the formation factor) are in agreement with independent evaluations of these parameters using the osmotic pressure determined from in situ pressure measurements and HTO diffusion experiments.