How NaCl addition destabilizes ionic liquid micellar suspension until phase separation

The ionic liquid tributyltetradecylphosphonium chloride ([P4,4,4,14]Cl) forms micelles in water, with a very low CMC, below 1 wt%. The solution is macroscopically homogeneous, even large amounts of [P4,4,4,14]Cl in water do not induce any phase separation. The ternary system [P4,4,4,14]Cl/NaCl/H2O i...

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Main Authors: Dufrêche, Jean-François, Plazanet, Marie, Meyer, Gautier, Billard, Isabelle
Format: Article
Language:English
Published: Académie des sciences 2024-04-01
Series:Comptes Rendus. Chimie
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Online Access:https://comptes-rendus.academie-sciences.fr/chimie/articles/10.5802/crchim.300/
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author Dufrêche, Jean-François
Plazanet, Marie
Meyer, Gautier
Billard, Isabelle
author_facet Dufrêche, Jean-François
Plazanet, Marie
Meyer, Gautier
Billard, Isabelle
author_sort Dufrêche, Jean-François
collection DOAJ
description The ionic liquid tributyltetradecylphosphonium chloride ([P4,4,4,14]Cl) forms micelles in water, with a very low CMC, below 1 wt%. The solution is macroscopically homogeneous, even large amounts of [P4,4,4,14]Cl in water do not induce any phase separation. The ternary system [P4,4,4,14]Cl/NaCl/H2O instead displays a LCST (Lower Critical Separation Temperature) behavior, being monophasic at low T and experiencing phase separation when T is increased. This phenomenon has been ascribed to the T-increased adsorption onto the micellar surface of these additional chloride ions. The lowering of the repulsive interactions between micelles finally allows coalescence and thus phase separation. In this work, we explore the impact of NaCl addition onto the phase separation, at fixed T. Specific chloride electrode allows the determination of chloride counterion adsorption for different samples in the phase diagram, all of them being single-phase. A simple theory based on the Poisson–Boltzmann equation and with charge regulation is proposed. The only fitted parameter is the chloride adsorption constant. It enables to model the different populations of ions in the solution and at the micelle surface in different conditions. Considering the effective charge of the micelles with respect to the ionic strength of the solution, it moreover provides a key element in the prediction of phase separation.
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spelling doaj-art-3182d3cc7bd84c75b7b670fc76cc7a6c2025-02-07T13:41:22ZengAcadémie des sciencesComptes Rendus. Chimie1878-15432024-04-011710.5802/crchim.30010.5802/crchim.300How NaCl addition destabilizes ionic liquid micellar suspension until phase separationDufrêche, Jean-François0https://orcid.org/0000-0001-8422-3639Plazanet, Marie1https://orcid.org/0000-0002-7041-8299Meyer, Gautier2Billard, Isabelle3https://orcid.org/0000-0002-2842-7706ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Bagnols-sur-Cèze, FranceLaboratoire Interdisciplinaire de Physique, LIPhy, CNRS & Univ. Grenoble-Alpes, Grenoble, FranceLaboratoire Interdisciplinaire de Physique, LIPhy, CNRS & Univ. Grenoble-Alpes, Grenoble, FranceUniv. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP, LEPMI, 38000 Grenoble, FranceThe ionic liquid tributyltetradecylphosphonium chloride ([P4,4,4,14]Cl) forms micelles in water, with a very low CMC, below 1 wt%. The solution is macroscopically homogeneous, even large amounts of [P4,4,4,14]Cl in water do not induce any phase separation. The ternary system [P4,4,4,14]Cl/NaCl/H2O instead displays a LCST (Lower Critical Separation Temperature) behavior, being monophasic at low T and experiencing phase separation when T is increased. This phenomenon has been ascribed to the T-increased adsorption onto the micellar surface of these additional chloride ions. The lowering of the repulsive interactions between micelles finally allows coalescence and thus phase separation. In this work, we explore the impact of NaCl addition onto the phase separation, at fixed T. Specific chloride electrode allows the determination of chloride counterion adsorption for different samples in the phase diagram, all of them being single-phase. A simple theory based on the Poisson–Boltzmann equation and with charge regulation is proposed. The only fitted parameter is the chloride adsorption constant. It enables to model the different populations of ions in the solution and at the micelle surface in different conditions. Considering the effective charge of the micelles with respect to the ionic strength of the solution, it moreover provides a key element in the prediction of phase separation.https://comptes-rendus.academie-sciences.fr/chimie/articles/10.5802/crchim.300/Aqueous biphasic solutionExtractionIonic liquidRegulation charge theory
spellingShingle Dufrêche, Jean-François
Plazanet, Marie
Meyer, Gautier
Billard, Isabelle
How NaCl addition destabilizes ionic liquid micellar suspension until phase separation
Comptes Rendus. Chimie
Aqueous biphasic solution
Extraction
Ionic liquid
Regulation charge theory
title How NaCl addition destabilizes ionic liquid micellar suspension until phase separation
title_full How NaCl addition destabilizes ionic liquid micellar suspension until phase separation
title_fullStr How NaCl addition destabilizes ionic liquid micellar suspension until phase separation
title_full_unstemmed How NaCl addition destabilizes ionic liquid micellar suspension until phase separation
title_short How NaCl addition destabilizes ionic liquid micellar suspension until phase separation
title_sort how nacl addition destabilizes ionic liquid micellar suspension until phase separation
topic Aqueous biphasic solution
Extraction
Ionic liquid
Regulation charge theory
url https://comptes-rendus.academie-sciences.fr/chimie/articles/10.5802/crchim.300/
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AT meyergautier hownacladditiondestabilizesionicliquidmicellarsuspensionuntilphaseseparation
AT billardisabelle hownacladditiondestabilizesionicliquidmicellarsuspensionuntilphaseseparation