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Phan A, Stamatakis M, Koh CA, Striolo A. Wetting Properties of Clathrate Hydrates in the Presence of Polycyclic Aromatic Compounds: Evidence of Ion-Specific Effects. J Phys Chem Lett 2022; 13:8200-8206. [PMID: 36006399 PMCID: PMC9442800 DOI: 10.1021/acs.jpclett.2c01846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) have attracted remarkable multidisciplinary attention due to their intriguing π-π stacking configurations, showing enormous opportunity for their use in a variety of advanced applications. To secure progress, detailed knowledge on PAHs' interfacial properties is required. Employing molecular dynamics, we probe the wetting properties of brine droplets (KCl, NaCl, and CaCl2) on sII methane-ethane hydrate surfaces immersed in various oil solvents. Our simulations show synergistic effects due to the presence of PAHs compounded by ion-specific effects. Our analysis reveals phenomenological correlations between the wetting properties and a combination of the binding free-energy difference and entropy changes upon oil solvation for PAHs at oil/brine and oil/hydrate interfaces. The detailed thermodynamic analysis conducted upon the interactions between PAHs and various interfaces identifies molecular-level mechanisms responsible for wettability alterations, which could be applicable for advancing applications in optics, microfluidics, biotechnology, medicine, as well as hydrate management.
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Affiliation(s)
- Anh Phan
- Department
of Chemical and Process Engineering, Faculty of Engineering and Physical
Sciences, University of Surrey, Guildford, Surrey GU2 7XH, United
Kingdom
| | - Michail Stamatakis
- Department
of Chemical Engineering, University College
London, London WC1E 7JE, United Kingdom
| | - Carolyn A. Koh
- Center
for Hydrate Research, Chemical & Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Alberto Striolo
- Department
of Chemical Engineering, University College
London, London WC1E 7JE, United Kingdom
- School
of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, Oklahoma 73019, United States
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Alicke A, Simon S, Sjöblom J, Vermant J. Assessing the Interfacial Activity of Insoluble Asphaltene Layers: Interfacial Rheology versus Interfacial Tension. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:14942-14959. [PMID: 33264021 DOI: 10.1021/acs.langmuir.0c02234] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Asphaltenes have been suggested to play an important role in the remarkable stability of some water-in-crude oil emulsions, although the precise mechanisms by which they act are not yet fully understood. Being one of the more polar fractions in crude oils, asphaltenes are surface active and strongly adsorb at the oil/water interface, and as the interface becomes densely packed, solid-like mechanical properties emerge, which influence many typical interfacial experiments. The present work focuses on purposefully measuring the rheology in the limit of an insoluble, spread Langmuir monolayer in the absence of adsorption/desorption phenomena. Moreover, the changes in surface tension are deconvoluted from the purely mechanical contribution to the surface stress by experiments with precise interfacial kinematics. Compression "isotherms" are combined with the measurement of both shear and dilatational rheological properties to evaluate the relative contributions of mechanical versus thermodynamic aspects, i.e., to evaluate the "interfacial rheological" versus the standard interfacial activity. The experimental results suggest that asphaltene nanoaggregates are not very efficient in lowering interfacial tension but rather impart significant mechanical stresses. Interestingly, physical aging effects are not observed in the spread layers, contrary to results for adsorbed layers. By further studying asphaltene fractions of different polarity, we investigate whether mere packing effects or strong interactions determine the mechanical response of the dense asphaltene systems as either soft glassy or gel-like responses have been reported. The compressional and rheological data reflect the dense packing, and the behavior is captured well by the soft glassy rheology model, but a more complicated multilayer structure may develop as coverage is increased. Potential implications of the experimental observations on these model and insoluble interfaces for water-in-crude oil emulsion stability are briefly discussed.
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Affiliation(s)
- Alexandra Alicke
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, Zurich 8093, Switzerland
| | - Sébastien Simon
- Department of Chemical Engineering, Ugelstad Laboratory, NTNU, N-7491 Trondheim, Norway
| | - Johan Sjöblom
- Department of Chemical Engineering, Ugelstad Laboratory, NTNU, N-7491 Trondheim, Norway
| | - Jan Vermant
- Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, Zurich 8093, Switzerland
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Abi Chebel N, Piedfert A, Lalanne B, Dalmazzone C, Noïk C, Masbernat O, Risso F. Interfacial Dynamics and Rheology of a Crude-Oil Droplet Oscillating in Water at a High Frequency. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:9441-9455. [PMID: 31257882 DOI: 10.1021/acs.langmuir.9b01594] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We report investigations of a pendant diluted crude-oil droplet in water that is forced to oscillate at a frequency ω. The droplet interface contains a significant amount of surface-active agents and displays a marked viscoelastic rheology with elastic moduli larger than viscous ones. At a low frequency, fluid viscosity and inertia are negligible, which allows a direct determination of the dilatational interface rheology. At a large frequency, eigenmodes of inertial shape oscillations are excited. By decomposing the interface shape into spherical harmonics, the resonance curves of the inertial modes of the interface are determined, as well as the frequency and damping rate of each mode. These two parameters are of major importance for the prediction of the deformation and breakup of a droplet in any unsteady flow without any prior knowledge of either the chemical composition or the detailed rheological properties of the interface. Then, interfacial rheology is related to interface dynamics by solving the coupled dynamic equations for the two fluids and the interface. It turns out that the rheology of the interface is well described by an equivalent two-dimensional viscoelastic material, the elasticities and viscosities of which depend upon the frequency. A first significant result is that shear and dilatational elasticities are closely connected, as are shear and dilatational viscosities. This implies that intrinsic rheology plays a major role and that compositional rheology is either negligible or strongly coupled to the intrinsic one. A second major result is that, for moderately aged droplets (≤5000 s), the elasticity and viscosity at a high frequency (10-80 Hz) can be extrapolated from low-frequency measurements (≤1 Hz) by a simple power law of the frequency, ωz. The exponent z is related to the loss angle θloss by a relation found in many previous low-frequency investigations of crude-oil interfaces: z = θloss/2π. The present work thus extends classic observations obtained at a low frequency to a higher frequency range corresponding to the natural frequency of the droplets, where the droplet shape results from the balance between dynamic pressure and surface stresses and the interface involves simultaneous shear and dilatation. These results bring about serious constraints regarding the modeling of physicochemical underlying mechanisms and provide some insights for the understanding of the structure of crude-oil interfaces.
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Affiliation(s)
- Nicolas Abi Chebel
- Institut de Mécanique des Fluides de Toulouse (IMFT), Université de Toulouse, CNRS , 31400 Toulouse , France
- Laboratoire de Génie Chimique (LGC), Université de Toulouse, CNRS , 31432 Toulouse , France
- FR FERMAT, Université de Toulouse, CNRS, INPT, INSA, UPS , Toulouse , France
| | - Antoine Piedfert
- Institut de Mécanique des Fluides de Toulouse (IMFT), Université de Toulouse, CNRS , 31400 Toulouse , France
- Laboratoire de Génie Chimique (LGC), Université de Toulouse, CNRS , 31432 Toulouse , France
- FR FERMAT, Université de Toulouse, CNRS, INPT, INSA, UPS , Toulouse , France
| | - Benjamin Lalanne
- Laboratoire de Génie Chimique (LGC), Université de Toulouse, CNRS , 31432 Toulouse , France
- FR FERMAT, Université de Toulouse, CNRS, INPT, INSA, UPS , Toulouse , France
| | - Christine Dalmazzone
- IFP Energies nouvelles , 1-4 avenue de Bois Préau , 92852 Rueil-Malmaison , France
| | - Christine Noïk
- IFP Energies nouvelles , 1-4 avenue de Bois Préau , 92852 Rueil-Malmaison , France
| | - Olivier Masbernat
- Laboratoire de Génie Chimique (LGC), Université de Toulouse, CNRS , 31432 Toulouse , France
- FR FERMAT, Université de Toulouse, CNRS, INPT, INSA, UPS , Toulouse , France
| | - Frédéric Risso
- Institut de Mécanique des Fluides de Toulouse (IMFT), Université de Toulouse, CNRS , 31400 Toulouse , France
- FR FERMAT, Université de Toulouse, CNRS, INPT, INSA, UPS , Toulouse , France
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