Dielectric relaxation spectroscopy of aqueous micellar electrolyte solutions: A novel application to infer Dukhin number and zeta potential of a micelle

Khademi, Mahmoud; Barz, Dominik P. J.

doi:10.1002/elps.201800293

Cited by 3 publications

(3 citation statements)

References 57 publications

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“…On the one hand, the zwitterionic TDAPS does not carry a net charge which makes the determination of an ionic strength difficult. On the other hand, the ionic strength of an SDS solution depends on the concentration of free surfactant molecules, on the degree of dissociation of the surfactant, and, for concentrations above CMC, on the micelle number density and aggregation number . Hence, we plot the EDL capacitance versus the surfactant concentration in Figure .…”

Section: Resultsmentioning

confidence: 99%

“…From conductivity data retrieved from the liquid bulk semicircle, along with a micelle size of around 5 nm measured with Direct Light Scattering, we can estimate the ionic strength of TDAPS for the highest concentration to be ∼1 mM. According to the analysis provided in our previous work, 68 the solution with the highest SDS concentration has an ionic strength of ∼10 mM. As it can be seen in Figure 6, both surfactants solutions result in very similar EDL capacitances of around 9 to 11 μF/cm 2 .…”

Section: Capacitance In Aqueous Surfactant Solutionsmentioning

confidence: 99%

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Structure of the Electrical Double Layer Revisited: Electrode Capacitance in Aqueous Solutions

Khademi

Barz

2020

Langmuir

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The structure of the electrical double layer at the interface of planar electrodes and aqueous solutions is investigated. Electrical impedance spectroscopy is used to measure the impedance of aqueous solutions of sodium chloride and two different surfactants over a wide range of concentrations. The electrode capacitance is directly inferred from the admittance spectra, as well as by regression of the impedance spectra to an equivalent circuit. It is found that the electrode capacitance remains on the same order of magnitude over the entire range of investigated concentrations. This is contradictive to the predictions of the Gouy-Chapman-Stern theory which predicts that at low concentrations, the electrode capacitance should be determined by the diffuse layer. It is concluded that the Stern layer capacitance always dominates the electrode capacitance, even at very low concentrations, and the establishment of a diffuse layer capacitance 1 requires an ionic strength of around 1 mM.

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Section: Resultsmentioning

confidence: 99%

Section: Capacitance In Aqueous Surfactant Solutionsmentioning

confidence: 99%

Structure of the Electrical Double Layer Revisited: Electrode Capacitance in Aqueous Solutions

Khademi

Barz

2020

Langmuir

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“…In dielectric spectroscopy at low frequencies, the EDL of the electrodes (EEDL) is common to separate from the relaxation of the EDL of the sample. Compensating the EP effect by an algorithm is used to determine the sample’s dielectric constant [ 9 ] and the zeta potential [ 10 ]—another approach to reduce the EP is via the four-electrode technique implying high specific instrumentation [ 11 ]. Furthermore, relaxation times have been used to characterize particles in aqueous suspensions, establishing a relation between the particle size and concentration with the characteristic time [ 12 , 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Effective Capacitance from Equivalent Electrical Circuit as a Tool for Monitoring Non-Adherent Cell Suspensions at Low Frequencies

et al. 2022

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Analyzing the electrical double layer (EDL) in electrical impedance spectroscopy (EIS) measurement at low frequencies remains a challenging task for sensing purposes. In this work, we propose two approaches to deal with the EDL in measuring impedance for particles and non-adherent cells in an electrolytic suspension. The first approach is a simple procedure to compute a normalized electrical impedance spectrum named dispersed medium index (DMi). The second is the EIS modeling through an equivalent electric circuit based on the so-called effective capacitance (Cef), which unifies the EDL phenomena. Firstly, as an experiment under controlled conditions, we examine polymer particles of 6, 15, and 48 μm in diameter suspended in a 0.9% sodium chloride solution. Subsequently, we used K-562 cells and leukocytes suspended in a culture medium (RPMI-1640 supplemented) for a biological assay. As the main result, the DMi is a function of the particle concentration. In addition, it shows a tendency with the particle size; regardless, it is limited to a volume fraction of 0.03 × 10−4 to 58 × 10−4. The DMi is not significantly different between K-562 cells and leukocytes for most concentrations. On the other hand, the Cef exhibits high applicability to retrieve a function that describes the concentration for each particle size, the K-562 cells, and leukocytes. The Cef also shows a tendency with the particle size without limitation within the range tested, and it allows distinction between the K-562 and leukocytes in the 25 cells/µL to 400 cells/µL range. We achieved a simple method for determining an Cef by unifying the parameters of an equivalent electrical circuit from data obtained with a conventional potentiostat. This simple approach is affordable for characterizing the population of non-adherent cells suspended in a cell culture medium.

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Dielectric relaxation studies of aqueous primary amines using a time domain reflectometry

Deshmukh

Kumbharkhane

2022

Indian J Phys

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Dielectric relaxation spectroscopy of aqueous micellar electrolyte solutions: A novel application to infer Dukhin number and zeta potential of a micelle

Abstract: CMC critical micelle concentration, DRS dielectric relaxation spectroscopy, EDL electrical double layer.

Cited by 3 publications

References 57 publications

Structure of the Electrical Double Layer Revisited: Electrode Capacitance in Aqueous Solutions

Structure of the Electrical Double Layer Revisited: Electrode Capacitance in Aqueous Solutions

Effective Capacitance from Equivalent Electrical Circuit as a Tool for Monitoring Non-Adherent Cell Suspensions at Low Frequencies

Dielectric relaxation studies of aqueous primary amines using a time domain reflectometry

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