Thermoresponsive Ionic Liquid/Water Mixtures: From Nanostructuring to Phase Separation

Forero-Martinez, Nancy C.; Cortes-Huerto, Robinson; Benedetto, Antonio; Ballone, Pietro

doi:10.3390/molecules27051647

Cited by 15 publications

(9 citation statements)

References 193 publications

(291 reference statements)

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“…They exhibited a typical LCST-type phase separation behavior by changing the IL concentration as shown in their phase diagrams (Figure c). The V-shaped lines indicate the liquid–liquid phase separation boundary that divides homogeneous phase and heterogeneous phase regions. ,, The LCST transition of the aqueous [P 4444 ][SS] solution was approximately 44, 31, 27, 25, 24, 22, 24, 26, and 33 °C at concentrations of 10, 15, 20, 25, 30, 35, 40, 45, and 50 wt %, respectively. On the other hand, the LCST of [N 4444 ][SS] was higher than that of [P 4444 ][SS].…”

Section: Resultsmentioning

confidence: 99%

Effect of the Structural Changes in a Styrenesulfonate-Based Draw Solute Having a Lower Critical Solution Temperature for the Forward Osmosis Process

Moon

Seo

Kang

2022

Ind. Eng. Chem. Res.

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Thermo-responsive ionic liquids, tributylalkylphosphonium styrenesulfonate ([P444#][SS], # = 4, 6, and 8) and tetrabutylammonium styrenesulfonate ([N4444][SS]), were synthesized to investigate the possibility of using a draw solute in forward osmosis, where # is the number of carbons of the alkyl groups in tributylalkylphosphonium. ILs in an aqueous solution exhibited a lower critical solution temperature (LCST)-type phase transition, which enables the recovery of the draw solute or water from the diluted draw solution. LCSTs of 50 wt % aqueous [P4444][SS] and [N4444][SS] solutions were approximately 33 and 66 °C, respectively. The water and reverse solute fluxes of the [P4444][SS] aqueous solution, which is more efficient in terms of solute recovery, were approximately 8.51 LMH and 1.66 gMH at 50 wt %, respectively, in the active layer facing the draw solution mode. This study demonstrates that an ionic structured material with thermo-responsive properties is a promising draw solute.

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Section: Resultsmentioning

confidence: 99%

Effect of the Structural Changes in a Styrenesulfonate-Based Draw Solute Having a Lower Critical Solution Temperature for the Forward Osmosis Process

Moon

Seo

Kang

2022

Ind. Eng. Chem. Res.

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“…20 In this context, thermoresponsive polymer−water mixtures have already been considered and partly developed, reaching the initial testing stage. 21 Selected organic ionic liquids (ILs) whose water solutions are thermoresponsive might also play a crucial role 22 and could offer some advantages with respect to polymer-based materials. First, their optimal composition for thermoresponsiveness often requires less water than for polymers.…”

Section: Introductionmentioning

confidence: 99%

Water Harvesting by Thermoresponsive Ionic Liquids: A Molecular Dynamics Study of the Water Absorption Kinetics and of the Role of Nanostructuring

et al. 2023

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Ionic liquids (ILs) whose water solutions are thermoresponsive provide an appealing route to harvest water from the atmosphere at an energy cost that can be accessed by solar heating. IL/water solutions that present a lower critical solution temperature (LCST), i.e., demix upon increasing temperature, represent the most promising choice for this task since they could absorb vapor during the night when its saturation is highest and release liquid water during the day. The kinetics of water absorption at the surface and the role of nanostructuring in this process have been investigated by atomistic molecular dynamics simulations for the ionic liquid tetrabutyl phosphonium 2,4-dimethylbenzenesulfonate whose LCST in water occurs at T c = 36 °C for solutions of 50–50 wt % composition. The simulation results show that water molecules are readily adsorbed on the IL and migrate along the surface to form thick three-dimensional islands. On a slightly longer time scale, ions crawl on these islands, covering water and recreating the original surface whose free energy is particularly low. At a high deposition rate, this mechanism allows the fast incorporation of large amounts of water, producing subsurface water pockets that eventually merge into the populations of water-rich and IL-rich domains in the nanostructured bulk. Simulation results suggest that strong nanostructuring could ease the separation of water and water-contaminated IL phases even before macroscopic demixing.

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“…Thermo-responsive systems can exhibit an upper or lower critical solution temperature (UCST/LCST), depending on whether entropic (LCST) or enthalpic (UCST) terms dominate, led by solute-water interactions, mostly hydrogen bonding and strong polar interactions (Kohno and Ohno, 2012). Looking beyond the design of integrated reaction-separation systems, thermoresponsive systems were further demonstrated as draw solutions for forward osmosis desalination (Zhong et al, 2016) or heat storage media (Forero-Martinez et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Tuning the ionic character of sodium dodecyl sulphate via counter-ion binding: An experimental and computational study

et al. 2022

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Solutions of surfactants exhibit remarkable features, such as a tunable amphiphilic character, which can further be varied for ionic surfactants through variations in their Coulombic interactions. These properties are very useful in many industrial applications such as in extraction, purification, and formulation processes, as detergents, wetting agents, or emulsifiers. Rather unexpectedly, the addition of tetrabutylammonium chloride ([N4,4,4,4]Cl) to solutions of the ionic surfactant of sodium dodecyl sulphate (SDS) results in the appearance of a phase transition above the lower critical solution temperature (LCST), a property usually associated with non-ionic surfactants. The aim of this study is to provide a detailed nanoscopic scenario on the interaction between SDS micelles and [N4,4,4,4]Cl moieties to better understand the nature of the LCST cloud point and how to confer it to a given ionic surfactant system. A coarse-grained molecular dynamics (CG-MD) computational framework, under the latest MARTINI 3.0 force field, was developed and validated using available literature data. The impact of [N4,4,4,4]Cl concentration in the phase of SDS micellar aqueous solutions was then characterized and compared using experimental results. Specifically, dynamic light scattering (DLS) measurements and small-angle X-ray scattering (SAXS) profiles were obtained at different [N4,4,4,4]+/[DS]- molar ratios (from 0.0 to 1.0) and compared with the CG-MD results. A good agreement between computer simulations and experimental findings was obtained, reinforcing the suitability of GC-MD to simulate complex phase behaviors. When the [N4,4,4,4]+/[DS]- molar ratio is < 0.5, a weak impact of the cation in the micellar distribution was found whereas for ratios > 0.5, the system yielded clusters of enclosed small [DS]- aggregates. Thus, the CG-MD simulations showed the formation of mixed [DS]- and [N4,4,4,4]+ aggregates with [N4,4,4,4]+ cations acting as a bridge between small [DS]- micelles. The CG-MD simulation framework developed in this work captured the role of [N4,4,4,4]+ in the micellar phase transition whilst improving the results obtained with preceding computer models for which the limitations on capturing SDS and [N4,4,4,4]Cl mixtures in aqueous solutions are also shown in detail.

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Thermoresponsive Ionic Liquid/Water Mixtures: From Nanostructuring to Phase Separation

Cited by 15 publications

References 193 publications

Effect of the Structural Changes in a Styrenesulfonate-Based Draw Solute Having a Lower Critical Solution Temperature for the Forward Osmosis Process

Effect of the Structural Changes in a Styrenesulfonate-Based Draw Solute Having a Lower Critical Solution Temperature for the Forward Osmosis Process

Water Harvesting by Thermoresponsive Ionic Liquids: A Molecular Dynamics Study of the Water Absorption Kinetics and of the Role of Nanostructuring

Tuning the ionic character of sodium dodecyl sulphate via counter-ion binding: An experimental and computational study

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