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Hadji C, Dollet B, Coasne B, Lorenceau E. Soap-Film Membranes for CO 2/Air Separation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:1327-1334. [PMID: 38170183 DOI: 10.1021/acs.langmuir.3c02915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Thin liquid films are a potential game changer in the quest for efficient gas separation strategies. Such fluid membranes, which are complementary to their solid counterparts involving porous materials, can achieve complex separation by combining permeability and adsorption mechanisms in their liquid core and at their surface. In addition, unlike porous solid membranes that must be regenerated between separation steps to recover a gas-free porosity, thus preventing continuous operation, liquid membranes can be regenerated using continuous liquid flow through the fluid film. Here, building on the self-sustained mobile film technique, we propose a simple experimental setup allowing direct quantitative assessment of the gas permeability of soap films stabilized by different surfactant types. Using a simple prototypical example involving O2/N2 mixtures, the measurement principle is first presented to establish a proof of concept. As the gas solubilities and diffusivities are known, the results of such experiments can be compared with microscopic models to disentangle the liquid core and surface permeabilities from a direct macroscopic transport response of the film subjected to a gas concentration difference. The same dynamical experiments performed for air enriched in CO2 indicate that the permeability of the soap film varies with the molar fraction in the gas compartment, a feature not observed for O2/N2. These experimental findings pave the way for the design of novel separation technologies in fields and situations where porous solid membranes are of limited efficiency.
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Affiliation(s)
- Céline Hadji
- Univ. Grenoble Alpes, CNRS, LIPhy, Grenoble 38000, France
| | | | - Benoît Coasne
- Univ. Grenoble Alpes, CNRS, LIPhy, Grenoble 38000, France
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Skrypnik A, Knüpfer L, Trtik P, Tholan V, Parkes S, Heitkam S. Neutron radiography of liquid foam structure near a vertical wall. SOFT MATTER 2023; 19:8552-8560. [PMID: 37901935 DOI: 10.1039/d3sm00983a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2023]
Abstract
At a solid boundary, the structural formation of bubbles is different from that in the bulk of a liquid foam. The presence of a solid boundary imposes additional constraints, resulting in a crystalline arrangement of the bubbles. For dry and monodisperse foam, the Kelvin and Fejes-Tóth structure is expected in the vicinity of the wall, while a random ordering should occur in the bulk. In this study, we investigate the transition from a crystalline to a random structure near a vertical wall located in the middle of a flat foam cell. The corresponding layering of the liquid was quantified by measuring the distribution of liquid fraction within the cell using neutron radiography. The amplitude of the liquid fraction distribution and its decay with distance from the solid boundary were correlated with the foam bubble size and polydispersity. Furthermore, by applying forced drainage, we measured the corresponding permeability and wetting front velocity near the vertical wall. We found that the crystalline sorting reduces the permeability and wetting front velocity compared to a randomly packed foam.
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Affiliation(s)
- Artem Skrypnik
- TU Dresden, Institute of Process Engineering and Environmental Technology, 01062 Dresden, Germany.
| | - Leon Knüpfer
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics, 01328 Dresden, Germany
| | - Pavel Trtik
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Switzerland
| | - Vaishakh Tholan
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics, 01328 Dresden, Germany
| | - Siân Parkes
- Newcastle Institute for Energy and Resources, University of Newcastle, Callaghan, Australia
| | - Sascha Heitkam
- TU Dresden, Institute of Process Engineering and Environmental Technology, 01062 Dresden, Germany.
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics, 01328 Dresden, Germany
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Dollet B. Coarsening of Foams Driven by Concentration Gradients of Gases of Different Solubilities. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:16174-16181. [PMID: 37916799 DOI: 10.1021/acs.langmuir.3c02533] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
The evolution of a foam driven by the transfer of two gases of different solubilities across the soap films is studied. A bamboo foam, or a train of films, is used as a model system; it is made of a poorly soluble gas and put into contact with a reservoir of a soluble gas at an initial time. The measurement of the time evolution of the volume of each bubble shows that the foam swells as it progressively incorporates the soluble gas. The dynamics is modeled from the gas fluxes across each film. The continuous limit of this model at a large number of bubbles is studied in detail: it gives an effective nonlinear diffusion equation, which fits the data very well. The corresponding diffusion constant, given by the product of the permeability of the soluble gas and the initial size of the bubbles, is shown to be the key parameter governing the coarsening dynamics of the foam.
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Ham S, Wang X, Nair AKN, Sun S, Lattimer B, Qiao R. Transport of Heptane Molecules across Water-Vapor Interfaces Laden with Surfactants. J Phys Chem B 2023. [PMID: 37410979 DOI: 10.1021/acs.jpcb.3c02618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/08/2023]
Abstract
Molecular transport across liquid-vapor interfaces covered by surfactant monolayers plays a key role in applications such as fire suppression by foams. The molecular understanding of such transport, however, remains incomplete. This work uses molecular dynamics simulations to investigate the heptane transport across water-vapor interfaces populated with sodium dodecyl sulfate (SDS) surfactants. Heptane molecules' potential of mean force (PMF) and local diffusivity profiles across SDS monolayers with different SDS densities are calculated to obtain heptane's transport resistance. We show that a heptane molecule experiences a finite resistance as it crosses water-vapor interfaces covered by SDS. Such interfacial transport resistance is contributed significantly by heptane molecules' high PMF in the SDS headgroup region and their slow diffusion there. This resistance increases linearly as the SDS density rises from zero but jumps as the density approaches saturation when its value is equivalent to that afforded by a 5 nm thick layer of bulk water. These results are understood by analyzing the micro-environment experienced by a heptane molecule crossing SDS monolayers and the local perturbation it brings to the monolayers. The implications of these findings for the design of surfactants to suppress heptane transport through water-vapor interfaces are discussed.
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Affiliation(s)
- Seokgyun Ham
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Xin Wang
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Arun Kumar Narayanan Nair
- Department of Earth Science and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Shuyu Sun
- Department of Earth Science and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Brian Lattimer
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Rui Qiao
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
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Trinh P, Mikhailovskaya A, Lefèvre G, Pantoustier N, Perrin P, Lorenceau E, Dollet B, Monteux C. Relation between oxidation kinetics and reactant transport in an aqueous foam. J Colloid Interface Sci 2023; 643:267-275. [PMID: 37068360 DOI: 10.1016/j.jcis.2023.03.140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/17/2023] [Accepted: 03/22/2023] [Indexed: 04/09/2023]
Abstract
HYPOTHESIS Aqueous foams are expected to constitute exquisite particularly suitable reactive medium for the oxidation of metals, since the reactant H+ can be supplied through the continuous liquid phase, while the reactant O2 can be transported through the gas bubbles. EXPERIMENTS To test this hypothesis, we investigated the oxidation of a metallic copper cylinder immersed in an aqueous foam. To study the relation between the transport of these reactants and the kinetics of the chemical reaction we use a forced drainage setup which enables us to control both the advection velocity of the H+ ions through the foam and the foam liquid fraction. FINDINGS We find experimentally that the mass of dissolved copper presents a maximum with the drainage flow rate, and thus with the foam liquid fraction. Modeling analytically the transfer of H+ and O2 through the foams enables us to show that this non-monotonic behavior results from a competition between the advective flux of H+ ions and the unsteady diffusion of O2 through the thin liquid films which tends to be slower as the area of the thin liquid films decreases with the drainage flow rate and the liquid fraction. This study shows for the first time how to optimize the foam structure and drainage flow in reactive foams in which the reactants are present both in the liquid and gaseous phases.
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Affiliation(s)
- Pierre Trinh
- Soft Matter Science and Engineering, CNRS, ESPCI, PSL University, Sorbonne University, 10 rue Vauquelin, 75005 Paris, France
| | - Alesya Mikhailovskaya
- Soft Matter Science and Engineering, CNRS, ESPCI, PSL University, Sorbonne University, 10 rue Vauquelin, 75005 Paris, France
| | - Grégory Lefèvre
- Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris (IRCP), F-75005 Paris, France
| | - Nadège Pantoustier
- Soft Matter Science and Engineering, CNRS, ESPCI, PSL University, Sorbonne University, 10 rue Vauquelin, 75005 Paris, France
| | - Patrick Perrin
- Soft Matter Science and Engineering, CNRS, ESPCI, PSL University, Sorbonne University, 10 rue Vauquelin, 75005 Paris, France
| | | | | | - Cécile Monteux
- Soft Matter Science and Engineering, CNRS, ESPCI, PSL University, Sorbonne University, 10 rue Vauquelin, 75005 Paris, France
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Andrieux S, Muller P, Kaushal M, Macias Vera NS, Bollache R, Honorez C, Cagna A, Drenckhan W. Microfluidic thin film pressure balance for the study of complex thin films. LAB ON A CHIP 2021; 21:412-420. [PMID: 33349822 DOI: 10.1039/d0lc00974a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Investigations of free-standing liquid films enjoy an increasing popularity due to their relevance for many fundamental and applied scientific problems. They constitute soap bubbles and foams, serve as membranes for gas transport or as model membranes in biophysics. More generally, they provide a convenient tool for the investigation of numerous fundamental questions related to interface- and confinement-driven effects in soft matter science. Several approaches and devices have been developed in the past to characterise reliably the thinning and stability of such films, which were commonly created from low-viscosity, aqueous solutions/dispersions. With an increasing interest in the investigation of films made from strongly viscoelastic and complex fluids that may also solidify, the development of a new generation of devices is required to manage reliably the constraints imposed by these formulations. We therefore propose here a microfluidic chip design which allows for the reliable creation, control and characterisation of free-standing films of complex fluids. We provide all technical details and we demonstrate the device functioning for a larger range of systems via a selection of illustrative examples, including films of polymer melts and gelling hydrogels.
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Affiliation(s)
- Sébastien Andrieux
- Université de Strasbourg, CNRS, Institut Charles Sadron UPR22, F-67000, Strasbourg, France.
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