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Evaporation in a single channel in the presence of particles. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.130432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Particle Deposition in Drying Porous Media. MATERIALS 2021; 14:ma14185120. [PMID: 34576344 PMCID: PMC8471196 DOI: 10.3390/ma14185120] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 08/30/2021] [Accepted: 09/02/2021] [Indexed: 11/17/2022]
Abstract
The drying of porous media is a ubiquitous phenomenon in soils and building materials. The fluid often contains suspended particles. Particle deposition may modify significantly the final material, as it could be pollutants or clogging the pores, decreasing the porosity, such as in salt, in which particles and drying kinetics are coupled. Here, we used SEM and X-ray microtomography to investigate the dried porous media initially saturated by nanoparticle suspensions. As the suspensions were dried, nanoparticles formed a solid deposit, which added to the initial solid matrix and decreased the porosity. We demonstrate that since the drying occurred through the top surface, the deposit is not uniform as a function of depth. Indeed, the particles were advected by the liquid flow toward the evaporative surface; the deposit was significant over a depth that depended on the initial volume fraction, but the pore size was affected over a very narrow length. These findings were interpreted in the frame of a physical model. This study may help to design better porous media and take into account particle influence in drying processes.
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Ben Abdelouahab N, Gossard A, Rodts S, Coasne B, Coussot P. Convective drying of a porous medium with a paste cover. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2019; 42:66. [PMID: 31123876 DOI: 10.1140/epje/i2019-11829-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/18/2019] [Indexed: 06/09/2023]
Abstract
The convective drying of a composite system made of a porous medium covered with a paste is a situation often encountered with soils, roads, building and cultural heritage materials. Here we discuss the basic mechanisms at work during the drying of a model composite system made of a homogeneous paste covering a simple granular packing. We start by reviewing the rather well-known case of the convective drying of a simple granular packing (i.e. without paste cover), which serves as a reference for physical interpretations. We show that a simple model assuming homogeneous desaturation followed by a progressive development of a dry front from the sample free surface is in agreement with observations of the internal liquid distribution variations in time. In particular, this model is able to reproduce the saturation vs. time curves of various simple granular systems, which supports our understanding of physical mechanisms at work. Then we show the detailed characteristics of drying of initially saturated model composite systems (with kaolin or cellulose paste) with the help of MRI measurements providing the liquid distribution in the sample at different times during the process up to the very last stages of drying. It appears that the granular medium is unaffected (i.e. remains saturated) during an initial period during which the paste shrinks and finally forms a sufficiently rigid porous structure which will not any more shrink later on. Then the drying process is governed by capillary effects down to very low saturation. Over a wide range of saturations both media desaturate homogeneously (within each medium) at different rates which depend on the specific porous structure of the media, so as to maintain capillary equilibrium throughout the sample. During these different stages the drying rate of the whole system remains constant. For sufficiently low saturation in the paste a dry front can develop, both in the paste and the porous medium below, and the drying rate now decreases. These results show that in a drying composite system liquid extraction can occur more or less simultaneously in the different parts of the material up to the very last stages of drying. The corresponding evolution of the distributions of liquid in the different parts of the sample also provides key information for the prediction of ion or particle transport and accumulation in the different parts of a composite system.
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Affiliation(s)
- N Ben Abdelouahab
- Univ. Paris-Est, Laboratoire Navier (ENPC-IFSTTAR-CNRS), 77420, Champs sur Marne, France
- CEA, DEN, Univ Montpellier, DE2D, SEAD, Laboratoire des Procédés Supercritiques et de Décontamination, Marcoule, 30207, Bagnols-sur-Cèze, France
| | - A Gossard
- CEA, DEN, Univ Montpellier, DE2D, SEAD, Laboratoire des Procédés Supercritiques et de Décontamination, Marcoule, 30207, Bagnols-sur-Cèze, France
| | - S Rodts
- Univ. Paris-Est, Laboratoire Navier (ENPC-IFSTTAR-CNRS), 77420, Champs sur Marne, France
| | - B Coasne
- Univ. Grenoble Alpes, CNRS, LIPhy, 38000, Grenoble, France
| | - P Coussot
- Univ. Paris-Est, Laboratoire Navier (ENPC-IFSTTAR-CNRS), 77420, Champs sur Marne, France.
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Goavec M, Rodts S, Gaudefroy V, Coquil M, Keita E, Goyon J, Chateau X, Coussot P. Strengthening and drying rate of a drying emulsion layer. SOFT MATTER 2018; 14:8612-8626. [PMID: 30324194 DOI: 10.1039/c8sm01490f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
From direct observations and MRI measurements we demonstrate that during the drying of a direct (oil in water) emulsion the whole system essentially concentrates homogeneously, which leads to shrinkage, without air penetration. The structure and mechanical strength (i.e. the elastic modulus) of this concentrated bulk are not significantly different from those of an emulsion directly prepared at this higher concentration. Despite this phenomenon, the drying rate continuously and rapidly decreases as the water content decreases, in contrast with the drying of a simple granular packing. This results from a concentration gradient which develops towards the free surface of the sample where the oil droplets finally coalesce, ultimately forming an oil layer covering the sample through which the water molecules have to diffuse before evaporating. Moreover, as during the process, the liquid is transported towards the free surface where it evaporates, surfactants accumulate and tend to form a thin solid layer below the oil layer, which tends to further reduce the drying rate.
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Affiliation(s)
- M Goavec
- Université Paris-Est, Laboratoire Navier (ENPC-IFSTTAR-CNRS), 2 Allée Kepler, 77420 Champs sur Marne, France.
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Seck MD, Keita E, Coussot P. Some Observations on the Impact of a Low-Solubility Ionic Solution on Drying Characteristics of a Model Porous Medium. Transp Porous Media 2018. [DOI: 10.1007/s11242-018-1169-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Zürcher J, Burg BR, Del Carro L, Studart AR, Brunschwiler T. On the Evaporation of Colloidal Suspensions in Confined Pillar Arrays. Transp Porous Media 2018. [DOI: 10.1007/s11242-018-1112-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Osman A, Goehring L, Patti A, Stitt H, Shokri N. Fundamental Investigation of the Drying of Solid Suspensions. Ind Eng Chem Res 2017. [DOI: 10.1021/acs.iecr.7b02334] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Abdulkadir Osman
- School
of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Lucas Goehring
- School
of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
| | - Alessandro Patti
- School
of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Hugh Stitt
- Johnson Matthey
Technology Centre, Billingham TS23 1LB, U.K
| | - Nima Shokri
- School
of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, United Kingdom
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