The Influence of Hydration upon the Potential at the Shear Plane (Zeta Potential) of a Hydrophobic Surface in the Presence of Various Electrolytes

1977 ◽  
pp. 245-256
Author(s):  
DONALD EAGLAND ◽  
ANTHONY P. ALLEN
Keyword(s):  
Zeta Potential ◽  
Hydrophobic Surface ◽  
Shear Plane ◽  
Influence Of Hydration

A dynamic Stern layer model to explain high salinity zeta potential measurements on sandstones

2020 ◽  
Author(s):  
Philippe Leroy ◽  
Shuai Li
Keyword(s):  
Electrical Properties ◽  
Zeta Potential ◽  
Water Flow ◽  
High Salinity ◽  
Surface Complexation ◽  
Streaming Potential ◽  
Shear Plane ◽  
Mineral Surface ◽  
Stern Layer ◽  
Counter Ions

<p>Exploring the electrical properties of the mineral-water interface for interpreting geophysical electrical measurements is a very challenging work because of the low specific surface area of minerals such as quartz or calcite. Only few methods exist to probe the properties of the electrical double layer (EDL) compensating the surface charge of minerals. Among them, there is the streaming potential (SP) method where the applied water pressure difference generates a pore water flow displacing the mobile counter-ions in excess in the EDL, hence creating a measurable electrical potential difference, the streaming potential. During SP measurements, the exact position of the shear plane from the mineral surface is not known and it is widely accepted that the shear plane is located between the compact Stern layer and the diffuse layer. In our study, we show that the assumption that there is no water flow in the Stern layer has no physical basis for sandstones in contact with a NaCl electrolyte because water molecules around counter-ions in the Stern layer may have bulk-like properties. Using a basic Stern model to simulate surface complexation reactions and considering water flow in the Stern layer, we reproduced the zeta potential measurements on sandstones over a large salinity range from about 10<sup>-2</sup> to 5.5 M NaCl. The “anomalous” high salinity zeta potential data can not be reproduced by a surface complexation model considering water flow only in the diffuse layer. Our ability to explain these measurements suggests that the shear plane may be located between the mineral surface and the Stern layer, i.e. closer to the surface than previously thought, which may have strong implications for the modelling of the surface electrical properties of the minerals.</p>

Stagnant Layer Conduction in Surfactant-Stabilized Hexadecane Emulsion Systems Measured by Electroacoustics

2003 ◽  
Vol 56 (10) ◽  
pp. 1081 ◽  
Author(s):  
Alex M. Djerdjev ◽  
James K. Beattie ◽  
Robert J. Hunter
Keyword(s):  
Zeta Potential ◽  
Size Distribution ◽  
Droplet Size ◽  
Volume Fraction ◽  
Sodium Dodecyl ◽  
Shear Plane ◽  
Surface Conductance ◽  
Zeta Potentials ◽  
Emulsion Droplets ◽  
Dynamic Mobility

Previously reported zeta-potentials calculated from the electroacoustic behaviour of sodium dodecyl sulfate (SDS) stabilized hexadecane emulsion droplets show certain anomalies. These can be resolved when electrical conduction in the stagnant layer behind the shear plane is included in the analysis. If stagnant layer conduction is ignored the addition of salt causes the apparent droplet size to increase and the magnitude of the zeta-potential to show a maximum. When stagnant layer conduction is included the dynamic mobility spectra can be fitted to a constant size distribution independent of the salt concentration with zeta-potentials that decrease as expected with increasing electrolyte concentration. Increasing SDS concentration, before the homogenization process, causes a decrease in droplet size and an increase in the total surface conductance to a constant value corresponding to the saturation of the surface with SDS. It is shown that the surface conductance and particle size distribution of hexadecane at any given volume fraction are functions of the concentration of SDS and the oil volume fraction. The zeta-potential changes log-linearly with added electrolyte and is independent of the SDS concentration or oil volume fraction used during the emulsification process.

The Deposition of Contaminants from Deionized Water onto Hydrophobic Silicon Wafers

1991 ◽  
Vol 34 (6) ◽  
pp. 28-34
Author(s):  
Deborah Riley ◽  
Ruben Carbonell
Keyword(s):  
Zeta Potential ◽  
Particle Deposition ◽  
Hydrophobic Surface ◽  
Contact Angles ◽  
Silicon Wafers ◽  
Deionized Water ◽  
Silicon Surfaces ◽  
Bulk Solution ◽  
Wafer Surface ◽  
Auger Analysis

The liquid-based deposition of particles onto hydrophobic silicon surfaces was investigated by exposing hydrophobic silicon wafers to sample contaminants in a stirred deionized water bath. Wafers were rendered hydrophobic by exposure to dilute hydrofluoric acid, and a goniometer was employed to monitor wafer contact angles. As has been observed in the past for hydrophilic wafers, the zeta potential recorded for the test particle had a significant impact on the deposition resulting on the hydrophobic silicon surfaces. This suggests that, despite treatment with HF and an overall hydrophobic surface behavior, regions remain on the wafer surface which are ionizable in aqueous solutions. The behavior of the silicon test wafers used in these studies is consistent with the presence of a negative zeta potential at the hydrophobic silicon surface. In contrast to the deposition seen on hydrophilic wafers, however, deposition onto hydrophobic silicon is frequently nonuniform. Additionally, Auger analysis indicates that hydrophobic surfaces show a marked tendency to attract hydrocarbon contaminants from the deionized (DI) water. The rinsing technique employed when rendering wafers hydrophobic was found to have a significant effect on baseline particulate levels, and test results indicate that contamination differences between hydrophobic and hydrophilic wafers may be more strongly related to exposure to gas/liquid interfaces than to differences in the rates of particle deposition in bulk solution.

Zeta potential in porous rocks in contact with monovalent and divalent electrolyte aqueous solutions

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. D303-D314 ◽  
Author(s):  
Luong Duy Thanh ◽  
Rudolf Sprik
Keyword(s):  
Zeta Potential ◽  
Streaming Potential ◽  
Shear Plane ◽  
Theoretical Models ◽  
Porous Rocks ◽  
Electrokinetic Phenomena ◽  
Reservoir Rocks ◽  
Partially Saturated ◽  
Different Types ◽  
Stern Potential

Electrokinetic phenomena are the result of a coupling between a fluid flow and an electric current flow in porous rocks. The zeta potential is an important parameter that influences the electrokinetic coupling. Most reservoir rocks are saturated or partially saturated by natural water containing various types of ions. Therefore, it is important to understand how the zeta potential and therefore the electric double layer (EDL) behave for different types of ions or electrolytes. Types of electrolytes influence the zeta potential most by affecting the surface charge — by changing the thickness of the EDL and the exact location of the shear plane. To study the dependence of the zeta potential on various electrolytes, we have carried out streaming potential measurements for consolidated rock samples saturated by monovalent and divalent electrolytes. From streaming potential coefficients, the zeta potential is obtained for different systems of electrolytes and rocks. The experimental results of silica-based rocks are then compared with theoretical models. For 1:1 or 1:2 electrolytes, a theoretical model for the zeta potential that has been available in literature is used. For 2:2 or 2:1 electrolytes, we have developed a new model to calculate the Stern potential and the zeta potential. The comparison found that the theoretical models can explain the main behavior of the zeta potential against types of electrolytes and types of silica-based rocks. The results show that the zeta potential for monovalent electrolytes is higher than that for divalent electrolytes. The zeta potential of the silica-based samples is higher than that of the nonsilica-based samples when they are saturated by the same types of electrolyte.

scholarly journals Charge-Based Separation of Micro- and Nanoparticles

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1014 ◽  
Author(s):  
Bao Ho ◽  
Jason Beech ◽  
Jonas Tegenfeldt
Keyword(s):  
Zeta Potential ◽  
Electric Fields ◽  
Lateral Displacement ◽  
Free Particle ◽  
Low Frequency ◽  
Shear Plane ◽  
Label Free ◽  
Experimental Conditions ◽  
Displacement Effect ◽  
Separation Science

Deterministic Lateral Displacement (DLD) is a label-free particle sorting method that separates by size continuously and with high resolution. By combining DLD with electric fields (eDLD), we show separation of a variety of nano and micro-sized particles primarily by their zeta potential. Zeta potential is an indicator of electrokinetic charge—the charge corresponding to the electric field at the shear plane—an important property of micro- and nanoparticles in colloidal or separation science. We also demonstrate proof of principle of separation of nanoscale liposomes of different lipid compositions, with strong relevance for biomedicine. We perform careful characterization of relevant experimental conditions necessary to obtain adequate sorting of different particle types. By choosing a combination of frequency and amplitude, sorting can be made sensitive to the particle subgroup of interest. The enhanced displacement effect due to electrokinetics is found to be significant at low frequency and for particles with high zeta potential. The effect appears to scale with the square of the voltage, suggesting that it is associated with either non-linear electrokinetics or dielectrophoresis (DEP). However, since we observe large changes in separation behavior over the frequency range at which DEP forces are expected to remain constant, DEP can be ruled out.

How to use alum with cationic dispersed rosin size

TAPPI Journal ◽  
2016 ◽  
Vol 15 (5) ◽  
pp. 331-335 ◽  
Author(s):  
LEBO XU ◽  
JEREMY MYERS ◽  
PETER HART
Keyword(s):  
Zeta Potential ◽  
Colloidal Particles ◽  
Streaming Potential ◽  
Excessive Amount ◽  
Paper Machine ◽  
Optimum Amount ◽  
Potential Measurement ◽  
Streaming Current ◽  
Wide Range ◽  
Laboratory Results

Retention of cationic dispersed rosin size was studied via turbidity measurements on stock filtrate with different alum and dispersed rosin size dosages. Stock charge characteristics were analyzed using both an analysis of charge demand determined via a streaming current detector and an evaluation of zeta potential of the fibers by streaming potential measurement. The results indicated that an optimum amount of alum existed such that good sizing retention was maintained throughout a wide range of dispersed rosin size dosages. However, when an excessive amount of alum was used and fines and colloidal particles were transitioned from anionic to cationic, the cationic size retention was reduced. Laboratory results were confirmed with a paper machine trial. All data suggested that a stock charge study was necessary to identify optimal alum dosage for a cationic dispersed rosin sizing program.

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