The impedance of solutions of AOT/water micelles in hexane

Новиков, Г. Ф.; Voilov, D. N.; Osipova, M. A.; Chernov, Ilya

doi:10.1134/s0036024407120205

Cited by 6 publications

(10 citation statements)

References 23 publications

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“…Previous studies of nonpolar fluids with EIS inferred the conductivity from the high-frequency portion of the spectra [10,16,17]. Here, we show that the electric permittivity of the solution can also be obtained.…”

Section: Introductionsupporting

confidence: 59%

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Use of electrochemical impedance spectroscopy to determine double-layer capacitance in doped nonpolar liquids

Yezer

Khair

Sides

et al. 2015

Journal of Colloid and Interface Science

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Section: Introductionsupporting

confidence: 59%

“…A constant-phase element [see Eq. (16)] must be used for the double-layer instead of a simple capacitor. The two parameters of the CPE (Q and a), together with the fluid resistance R f are then used to calculate the double-layer capacitance from Eq.…”

Section: Conclusion and Significancementioning

confidence: 99%

Use of electrochemical impedance spectroscopy to determine double-layer capacitance in doped nonpolar liquids

Yezer

Khair

Sides

et al. 2015

Journal of Colloid and Interface Science

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“…The other two surfactants are anionic, which provides a more straightforward explanation for their ability to form and stabilize charge. Aerosol OT is the most common surfactant used in charging studies and is commonly employed in its sodium form, 40,46,52,53,[56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72] though its calcium salt has also been used. 6 Zirconyl fatty acid salts have been used far less frequently, and normally only in one form, zirconyl 2-ethyl hexanoate (Zr(Oct) 2 ).…”

Section: Aggregation Of Surfactantsmentioning

confidence: 99%

Controlling colloid charge in nonpolar liquids with surfactants

Smith

Eastoe

2013

Phys. Chem. Chem. Phys.

146

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The formation of ions in nonpolar solvents (with relative permittivity ε r of approximately 2) is more difficult than in polar liquids; however, these charged species play an important role in many applications, such as electrophoretic displays. The low permittivities (ε r) of these solvents mean that charges have to be separated by large distances to be stable (approximately 28 nm or 40 times that in water). The inverse micelles formed by surfactants in these solvents provide an environment to stabilize ions and charges. Common surfactants used are sodium dioctylsulfosuccinate (Aerosol OT or AOT), polyisobutylene succinimide, sorbitan oleate, and zirconyl 2-ethyl hexanoate. The behavior of charged inverse micelles has been studied on both the bulk and on the microscopic scale and can be used to determine the motion of the micelles, their structure, and the nature of the electrostatic double layer. Colloidal particles are only weakly charged in the absence of surfactant, but in the presence of surfactants, many types, including polymers, metal oxides, carbon blacks, and pigments, have been observed to become positively or negatively charged. Several mechanisms have been proposed as the origin of surface charge, including acid-base reactions between the colloid and the inverse micelle, preferential adsorption of charged inverse micelles, or dissolution of surface species. While most studies vary only the concentration of surfactant, systematic variation of the particle surface chemistry or the surfactant structure have provided insight into the origin of charging in nonpolar liquids. By carefully varying system parameters and working to understand the interactions between surfactants and colloidal surfaces, further advances will be made leading to better understanding of the origin of charge and to the development of more effective surfactants.

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“…In order to pass an electric field and have an effective driving force, this solution needs to be more conductive than its current state. The use of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles is proposed to increase the conductivity of the organic phase [20][21][22]. This work endeavors to show that the application of a micellar organic phase and electric field will increase the Nd extraction percent in a liquid-liquid extraction system [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

“…In addition to increasing the conductivity of the organic phase, these reverse micelles may provide an added enhancement to the LLX system by reducing the surface tension between the aqueous and organic phases, allowing for increased Nd extraction [26]. The electrochemical characteristics (i.e., conductivity) of the reverse micelle-containing organic phase are proposed to be analyzed using the electrochemical impedance spectroscopy (EIS) [20,21,27] method.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Impedance Spectroscopy (EIS) Characterization of Water/Sodium Bis(2-Ethylhexyl) Sulfosuccinate-HDEHP/n-Dodecane Reverse Micelles for Electroextraction of Neodymium

2017

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The extraction and separation of metal ions in the lanthanide series using the liquid-liquid extraction (LLX) technique poses a major challenge due to the chemical similarities of the metals and hence interest exists in devising a technique to improve the separation factor. In this work, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) is explored for improved organic phase conductivity to aid the use of an imposed external field to improve the LLX. The electrochemical impedance spectroscopy (EIS) technique was used to determine the effect of molar water content, AOT and HDEHP (bis(2-ethylhexyl) phosphoric acid) concentration, and the temperature on the reverse micelle solution conductivity. Results showed that as AOT concentration and water content increases, conductivity increases until the reverse micelles collapse. The addition of HDEHP caused a significant drop in solution conductivity. For a mixed AOT and HDEHP system and at a small applied external field range of 0-1.4 kV m −1 and 60 rpm stir rate, a significant improvement in Nd extraction was observed relative to the traditional LLX using HDEHP only. With AOT only, a 40% improvement in extraction was observed with applied field relative to the absence of field. Cost consideration favors the use of mixed AOT and HDEHP at a slow stir rate for improved Nd extraction.

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The impedance of solutions of AOT/water micelles in hexane

Cited by 6 publications

References 23 publications

Use of electrochemical impedance spectroscopy to determine double-layer capacitance in doped nonpolar liquids

Use of electrochemical impedance spectroscopy to determine double-layer capacitance in doped nonpolar liquids

Controlling colloid charge in nonpolar liquids with surfactants

Electrochemical Impedance Spectroscopy (EIS) Characterization of Water/Sodium Bis(2-Ethylhexyl) Sulfosuccinate-HDEHP/n-Dodecane Reverse Micelles for Electroextraction of Neodymium

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