Electrokinetic Measurements Reveal Interfacial Charge at Polymer Films Caused by Simple Electrolyte Ions

Zimmermann, Ralf; Dukhin, and Stanislav; Werner, Carsten

doi:10.1021/jp004051u

Cited by 236 publications

(289 citation statements)

References 18 publications

Supporting

Mentioning

261

Contrasting

Unclassified

Order By: Relevance

“…[ ] Hydrophobic media possessing low dielectric permittivity like Teflon [52], air [27], or amorphous silica [29] are characterized by large hydration layers at their surface, which may allow the migration of hydrated protons (hydronium ions) along the particle surface via the hydrogen bonding network. We assume here that the calcite-water interface, also characterized by large hydration layers, allows the hydrated protons to move along the particle surface.…”

Section: Electrical Conductivity Modelmentioning

confidence: 99%

“…We assume here that the calcite-water interface, also characterized by large hydration layers, allows the hydrated protons to move along the particle surface. It is interesting to note that Holmes et al [53] considered the specific surface conductivity of ionizable surface hydroxyl groups at the surface of thorium oxide, and that Revil and co-workers [23,48], Zimmermann et al [52], and Leroy and co-workers [27,29] considered the contribution of protons to the specific surface conductivity of silica, Teflon, and air and silica, respectively. (23) and (24), the ion mobility, water dielectric permittivity, and viscosity in the diffuse layer are assumed to be equal to their values in bulk water, and d ϕ is the electrical potential at the beginning of the diffuse layer.…”

Section: Electrical Conductivity Modelmentioning

confidence: 99%

See 1 more Smart Citation

Influence of surface conductivity on the apparent zeta potential of calcite

Leroy

Heberling

et al. 2016

Journal of Colloid and Interface Science

114

View full text Add to dashboard Cite

Zeta potential is a physicochemical parameter of particular importance in describing the surface electrical properties of charged porous media. However, the zeta potential of calcite is still poorly known because of the difficulty to interpret streaming potential experiments. The HelmholtzSmoluchowski (HS) equation is widely used to estimate the apparent zeta potential from these experiments. However, this equation neglects the influence of surface conductivity on streaming potential. We present streaming potential and electrical conductivity measurements on a calcite powder in contact with an aqueous NaCl electrolyte. Our streaming potential model corrects the apparent zeta potential of calcite by accounting for the influence of surface conductivity and flow regime. We show that the HS equation seriously underestimates the zeta potential of calcite, particularly when the electrolyte is diluted (ionic strength ≤0.01 M) because of calcite surface conductivity. The basic Stern model successfully predicted the corrected zeta potential by assuming that the zeta potential is located at the outer Helmholtz plane, i.e. without considering a stagnant diffuse layer at the calcite-water interface. The surface conductivity of calcite crystals was inferred from electrical conductivity measurements and computed using our basic Stern model. Surface conductivity was also successfully predicted by our surface complexation model.

show abstract

Section: Electrical Conductivity Modelmentioning

confidence: 99%

Section: Electrical Conductivity Modelmentioning

confidence: 99%

Influence of surface conductivity on the apparent zeta potential of calcite

Leroy

Heberling

et al. 2016

Journal of Colloid and Interface Science

114

View full text Add to dashboard Cite

show abstract

“…Indeed, there is plenty of evidence that hydroxide ions bind more strongly than hydronium ions to polymer surfaces for polymers immersed in water, 14,73,[85][86][87][88][89] whereas protons prefer to be more completely hydrated. 90 Regarding the steric difference of the water ions, in protonated bulk liquid water, for instance, a particular stable complex is the Eigen cation (H 9 O 3 + ), which has a trigonal pyramidal structure, 91,92 whereas hydroxide ions have a resting state of four hydrogen bonds to water molecules in a square-planar arrangement. 93 Furthermore, it should be noted that protons have much higher mobility in water than hydroxide ions [µ H + = 36. .…”

Section: Water Dissociation and Ion Separationmentioning

confidence: 99%

“…This charge-separation process has been explained by a stronger adsorption of hydroxide ions than positive water ions to the channel walls. 74,90 The water ions stay in close proximity to each other in still water, but are separated in strong currents.…”

Section: E Analogies To the Proposed Triboelectric And Electrokinetimentioning

confidence: 99%

Squeezing out hydrated protons: low-frictional-energy triboelectric insulator charging on a microscopic scale

Knorr¹

2011

AIP Advances

View full text Add to dashboard Cite

Though triboelectric charging of insulators is common, neither its mechanism nor the nature of the charge is well known. Most research has focused on the integral amount of charge transferred between two materials upon contact, establishing, e.g., a triboelectric series. Here, the charge distribution of tracks on insulating polymer films rubbed by polymer-covered pointed swabs is investigated in high resolution by Kelvin probe force microscopy. Pronounced bipolar charging was observed for all nine rubbing combinations of three different polymers, with absolute surface potentials of up to several volts distributed in streaks along the rubbing direction and varying in polarity on μm-length scales perpendicular to the rubbing direction. Charge densities increased considerably for rubbing in higher relative humidity, for higher rubbing loads, and for more hydrophilic polymers. The ends of rubbed tracks had positively charged rims. Surface potential decay with time was strongly accelerated in increased humidity, particularly for polymers with high water permeability. Based on these observations, a mechanism is proposed of triboelectrification by extrusions of prevalently hydrated protons, stemming from adsorbed and dissociated water, along pressure gradients on the surface by the mechanical action of the swab. The validity of this mechanism is supported by explanations given recently in the literature for positive streaming currents of water at polymer surfaces and by reports of negative charging of insulators tapped by accelerated water droplets and of potential built up between the front and the back of a rubbing piece, observations already made in the 19th century. For more brittle polymers, strongly negatively charged microscopic abrasive particles were frequently observed on the rubbed tracks. The negative charge of those particles is presumably due in part to triboemission of electrons by polymer chain scission, forming radicals and negatively charged ions

show abstract

“…There have also been a number of studies about the electrical and chemical details at the interfaces: Lyklema 29 presents a comprehensive discussion of ion double-layer theories; Chou 30 presents an analytic solution for the liquid/gas shape right at the triple point under an applied potential; Zimmerman, Dukhin, and Werner 31 provide an experimental and theoretical treatment of potentials and solid/liquid conductivities due to ion adsorption; and Koopal and Avena 32 provide an excellent description of adsorption kinetics. We do not consider such fine-scale spatial details here.…”

Section: A Backgroundmentioning

confidence: 99%

Equilibrium behavior of sessile drops under surface tension, applied external fields, and material variations

Shapiro

Moon

Garrell

et al. 2003

Journal of Applied Physics

202

183

View full text Add to dashboard Cite

This article describes the equilibrium shape of a liquid drop under applied fields such as gravity and electrical fields, taking into account material properties such as dielectric constants, resistivities, and surface tension coefficients. The analysis is based on an energy minimization framework. A rigorous and exact link is provided between the energy function corresponding to any given physical phenomena, and the resulting shape and size dependent force term in Young's equation. In particular, the framework shows that a physical effect, such as capacitive energy storage in the liquid, will lead to 1/R ''line-tension''-type terms if and only if the energy of the effect is proportional to the radius of the liquid drop: EϰR. The effect of applied electric fields on shape change is analyzed. It is shown that a dielectric solid and a perfectly conducting liquid are all that is needed to exactly recover the Young-Lippmann equation. A dielectric liquid on a conducting solid gives rise to line tension terms. Finally, a slightly resistive liquid on top of a dielectric, highly resistive solid gives rise to contact angle saturation and accurately matches the experimental data that we observe in our electro-wetting-on-dielectric devices.

show abstract

Electrokinetic Measurements Reveal Interfacial Charge at Polymer Films Caused by Simple Electrolyte Ions

Cited by 236 publications

References 18 publications

Influence of surface conductivity on the apparent zeta potential of calcite

Influence of surface conductivity on the apparent zeta potential of calcite

Squeezing out hydrated protons: low-frictional-energy triboelectric insulator charging on a microscopic scale

Equilibrium behavior of sessile drops under surface tension, applied external fields, and material variations

Contact Info

Product

Resources

About