Role of water molecules in sodium bis(2-ethylhexyl) phosphate reversed micelles in n-heptane

Ibrahim, Taleb H.

doi:10.1016/j.jfranklin.2010.03.010

Cited by 8 publications

(5 citation statements)

References 15 publications

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“…For example, some aspects of the sodium diethylhexylphosphate (NaDEHP) surfactant, shown in Figure , appear similar to AOT including the double-branched alkyl tails and the sodium counterion. This surfactant has shown some utility for aqueous reverse micelle formation. ,− Preliminary results from our laboratory suggest that NaDEHP can dissolve both ethylene glycol and dimethylformamide making it a good candidate for nonaqueous reverse micelles. Likewise, can reverse micelles encapsulating nonaqueous organic polar solvent be created with cationic surfactants?…”

Section: Future Directions and Cautionsmentioning

confidence: 99%

Nonaqueous Polar Solvents in Reverse Micelle Systems

et al. 2012

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CONTENTS 1. Introduction 4569 2. Background 4569 2.1. Aqueous Reverse Micelles 4569 2.2. Definition of Aqueous and Nonaqueous Reverse Micelles 4572 3. Characterization of Reverse Micelles 4573 3.1. Methods Demonstrating the Presence of Reverse Micelles 4573 3.2. Surfactant Packing at the Reverse Micelle Interface 4574 4. Reverse Micelles Encapsulating Nonaqueous Polar Organic Solvents 4578 4.1. Reverse Micelles Containing Glycerol 4578 4.2. Reverse Micelles Containing Other Polyols 4580 4.3. Reverse Micelles Containing Formamide 4582 4.4. Reverse Micelles Containing Other Amides: DMF and DMA 4584 4.5. Other Polar Solvents 4585 5. Requirements for Effective Reverse Micelle Formation 4586 5.1. Polar Solvent Properties 4586 5.2. Problem Systems: Methanol and Acetonitrile 4587 6. Room Temperature Ionic Liquids in Reverse Micelles 4589 7. Nonaqueous Reverse Micelles as Nanoreactors 4593 8. Future Directions and Cautions 4596 Author Information 4597 Corresponding Author 4597 Notes 4597 Biographies 4597 Acknowledgments 4598 References 4598

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Section: Future Directions and Cautionsmentioning

confidence: 99%

Nonaqueous Polar Solvents in Reverse Micelle Systems

et al. 2012

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“…Synergistic extraction was only recently correlated with the synergistic micellization of the extractant molecules, which may also be named in aggregate when the reverse micelles are quite small. − In the case of the HDEHP-TOPO (respectively di-(2-ethyl-78 hexyl)phosphoric and acid-tri- n -octylphosphine oxide) synergistic system, the estimation of free energies of transfer was shown to be concomitantly minimized with the free energy of aggregation/micellization . However, in the absence of chelated cations in the cores of the aggregates, synergistic aggregation could no longer be observed. , Synergistic aggregation effects are therefore not intrinsic but rather depend implicitly on the chelation process because they represent a nucleation effect .…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Description of Synergy in Solvent Extraction: II Thermodynamic Balance of Driving Forces Implied in Synergistic Extraction

et al. 2017

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In the second part of this study, we analyze the free energy of transfer in the case of synergistic solvent extraction. This free energy of the transfer of an ion in dynamic equilibrium between two coexisting phases is decomposed into four driving forces combining long-range interactions with the classical complexation free energy associated with the nearest neighbors. We demonstrate how the organometallic complexation is counterbalanced by the cost in free energy related to structural change on the colloidal scale in the solvent phase. These molecular forces of synergistic extraction are driven not only by the entropic term associated with the tight packing of electrolytes in the solvent and by the free energy cost of coextracting water toward the hydrophilic core of the reverse aggregates present but also by the entropic costs in the formation of the reverse aggregate and by the interfacial bending energy of the extractant molecules packed around the extracted species. Considering the sum of the terms, we can rationalize the synergy observed, which cannot be explained by classical extraction modeling. We show an industrial synergistic mixture combining an amide and a phosphate complexing site, where the most efficient/selective mixture is observed for a minimal bending energy and maximal complexation energy.

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“…[16] Both geometry optimization and dynamic simulations indicate that NaDEHP aggregates that form in the organic phase are RMs. The main forces between the NaDEHP molecules are van der Waals and electrostatic forces.…”

Section: Introductionmentioning

confidence: 99%

Comparison between Two Anionic Reverse Micelle Interfaces: The Role of Water–Surfactant Interactions in Interfacial Properties

Quintana¹,

Falcone²,

Silber³

et al. 2011

ChemPhysChem

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The water/sodium bis(2-ethylhexyl) phosphate (NaDEHP) reverse micelle (RM) system is revisited by using, for the first time, molecular probes to investigate interface properties. The solvatochromic behavior of 1-methyl-8-oxyquinolinium betaine (QB) and 6-propionyl-2-(N,N-dimethyl)aminonaphthalene (PRODAN) in the water/NaDEHP/toluene system is studied, and the results are compared with those obtained in water/sodium 1,4-bis(2-ethylhexyl) sulfosuccinate (AOT)/toluene RM media. The results demonstrate that the micropolarity, microviscosity, interfacial water structure, molecular probe partition, and intramolecular electron-transfer processes are dramatically altered for NaDEHP RM interfaces in comparison to the AOT systems. Because of organic nonpolar solvent penetration into the interface, NaDEHP RM media offer an interface with lower micropolarity and microviscosity than AOT media. Also, the interfacial water in the NaDEHP system shows enhanced water-water hydrogen-bond interaction in comparison with bulk water. The AOT RM interface represents a unique environment for PRODAN to undergo dual emission.

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Role of water molecules in sodium bis(2-ethylhexyl) phosphate reversed micelles in n-heptane

Cited by 8 publications

References 15 publications

Nonaqueous Polar Solvents in Reverse Micelle Systems

Nonaqueous Polar Solvents in Reverse Micelle Systems

Thermodynamic Description of Synergy in Solvent Extraction: II Thermodynamic Balance of Driving Forces Implied in Synergistic Extraction

Comparison between Two Anionic Reverse Micelle Interfaces: The Role of Water–Surfactant Interactions in Interfacial Properties

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