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.

Electroacoustic Study of n-Hexadecane/Water Emulsions

2001 ◽  
Vol 54 (8) ◽  
pp. 503 ◽  
Author(s):  
Linggen Kong ◽  
James K. Beattie ◽  
Robert J. Hunter
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Volume Fraction ◽  
Sodium Dodecyl ◽  
Surfactant Solution ◽  
Minimum Size ◽  
Water Mixture ◽  
Concentrated Suspensions ◽  
Minimum Concentration ◽  
Median Diameter

n-Hexadecane-in-water emulsions were investigated by electroacoustics using a prototype of an AcoustoSizer-II apparatus. The emulsions were formed by passing the stirred oil/water mixture through a homogenizer in the presence of sodium dodecyl sulfate (SDS) at natural pH (6–7). With increasing oil-volume fraction, the particle size increased linearly after 5 and also after 20 passages through the homogenizer, suggesting that surface energy was determining particle size. For systems in which the surfactant concentration was limited, the particle size after 20 passages approached the value dictated by the SDS concentration. With ample surfactant present, the median diameter was a linear function of the inverse of the total energy input as measured by the number of passes. There was, however, a limit to the amount of size reduction that could be achieved in the homogenizer, and the minimum size was smaller at smaller volume fractions. Dilution of the emulsion with a surfactant solution of the same composition as the water phase had a negligible effect on the particle size and changed the zeta potential only slightly. This confirms results from previous work and validates the equations used to determine the particle size and zeta potential in concentrated suspensions. The minimum concentration of SDS that could prevent the emulsion from coalescing for the system with 6% by volume oil was 3 mM. For this dilute emulsion, the particle size decreased regularly with an increase in SDS concentration, but the magnitude of the zeta potential went through a strong maximum at intermediate surfactant concentrations.

scholarly journals Co-solvent Effect on Spontaneous Formation of Large Nanoscale Structures in Catanionic Mixtures in the Anionic-Rich Region

2019 ◽  
Vol 49 (1) ◽  
pp. 16-33 ◽  
Author(s):  
Farhad Golmohammadi ◽  
Masoud Amiri ◽  
Hussein Gharibi ◽  
Ali Yousefi ◽  
Meysam Safari
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Zeta Potential ◽  
Volume Fraction ◽  
Sodium Dodecyl ◽  
Nanoscale Structures ◽  
Transmission Electron ◽  
Air Liquid Interface ◽  
Catanionic Mixtures ◽  
Cosolvent Effects

AbstractThe aggregation behavior was investigated in mixtures of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) (anionic-rich catanionic) solutions. The study was conducted in solutions of water–ethylene glycol (EG) by means of surface tension, conductometry, cyclic voltammetry, zeta potential measurements, transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. The degree of counterion dissociation (α), critical micelle concentration, aggregation numbers, interfacial properties, interparticle interaction parameters, and morphology of aggregates were determined. Based on regular solution theory, the cosolvent effects between SDS and CTAB as surfactants were also analyzed for both mixed monolayers at mixed micelles (βM) and the air/liquid interface (βσ). It was shown that the formation of large aggregates occurred in the presence of an excess of anionic surfactant. A phase transition from cylindrical micelles to spherical micelles in the anionic-rich regime was observed with an increase in the EG volume fraction. The inter particle interactions were assessed in terms of cosolvent effects on the micellar surface charge density and the cylindrical-to-spherical morphology change. Zeta potential and size of the aggregates were determined using dynamic light scattering and confirmed the models suggested for the processes taking place in each system.

Interaction of gas bubbles and oil droplets in subsea oil and gas blowouts – a new development of VDROP-J model.

2017 ◽  
Vol 2017 (1) ◽  
pp. 2017-194
Author(s):  
Lin Zhao ◽  
Michel C. Boufadel ◽  
Feng Gao ◽  
Thomas King ◽  
Brian Robinson ◽  
...  
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Oil And Gas ◽  
Volume Fraction ◽  
Near Field ◽  
Gas Bubbles ◽  
Droplet Size Distribution ◽  
Oil Droplets ◽  
Oil Droplet ◽  
New Development

Abstract (2017-194) The presence of methane bubbles in the oil and gas blowout could greatly reduce the oil droplet sizes. Bubbles tend to introduce energy into the system and separate oil droplets from each other. The interaction of oil droplets and gas bubbles in the near field of a blowout was investigated numerically using the VDROP-J model, whose droplet size distribution (DSD) was thoroughly calibrated. For this purpose, a new numerical scheme has been developed in VDROP-J to account for the interaction of gas bubbles and oil droplets in the blowout, giving simultaneous simulation of bubble and droplet size distribution along the discharged plume. Validation shows improvement of the model compared with the one without considering the gas bubble and oil droplet interactions. Effects of gas volume fraction on the droplet formation are also investigated. This new development will enhance the knowledge in subsea oil and gas blowouts.

A Numerical Model for Oil Droplet Evolution Emanating from Blowouts

2014 ◽  
Vol 2014 (1) ◽  
pp. 561-571 ◽  
Author(s):  
Lin Zhao ◽  
Michel C. Boufadel ◽  
E. Eric Adams ◽  
Scott A. Socolofsky ◽  
Kenneth Lee
Keyword(s):  
Numerical Model ◽  
Size Distribution ◽  
Droplet Size ◽  
Volume Fraction ◽  
Control Volume ◽  
Droplet Size Distribution ◽  
Energy Dissipation Rate ◽  
Mixing Energy ◽  
Maximum Value ◽  
The Mean

ABSTRACT This paper presents the details of a numerical model that is capable of simulating the droplet size distribution emanating from blowouts. The model was obtained as a result of combination of traditional mechanistic models developed in reactors with jet (or plume) models to predict the evolution of the plume away from the orifice. Inputs to the model include the energy dissipation rate (or the mixing energy) and holdup, which is the volume fraction of oil in the control volume. These parameters vary as the plume spreads away from the orifice. They have a maximum value near the orifice and rapidly decrease as moving away from the orifice. The model was validated using experimental data available in the literature. Subsequently, the model was used to predict the evolution of droplets in the Deepwater Horizon incident. The model provides the variation of the mean diameter and the droplet size distribution with depths away from the orifice. The sensitivity of different parameters, such as interfacial tension which could present the addition of dispersants was also evaluated.

The zeta potential of kaolin suspensions measured by electrophoresis and electroacoustics

2007 ◽  
Vol 61 (2) ◽  
Author(s):  
R. Greenwood ◽  
B. Lapčíková ◽  
M. Surýnek ◽  
K. Waters ◽  
L. Lapčík
Keyword(s):  
Zeta Potential ◽  
Isoelectric Point ◽  
Anionic Surfactant ◽  
Sodium Dodecyl ◽  
Isomorphic Substitution ◽  
Concentrated Suspensions ◽  
Concentrated Suspension ◽  
Zeta Potentials ◽  
Maximum Value ◽  
Triton X

AbstractThe zeta potentials of kaolin dilute and concentrated suspensions were monitored using the techniques of electrophoresis and electroacoustics, respectively. The effect of addition of salt (KCl), a polymer material (Triton X-100), and an anionic surfactant (sodium dodecyl sulphate, SDS) on the suspension properties was investigated by electrophoresis. Electroacoustics was employed for the measurement of zeta potentials for the highest possible kaolin content in suspension and the effect of dilution. The effect of aging of a freshly prepared sample and kaolin isoelectric point was also studied. Using both techniques it was noted that there was no isoelectric point, just a maximum value in the magnitude of the kaolin suspension zeta potential. These maxima were observed also in the presence of Triton X-100 and SDS. An increase of the concentration of KCl and SDS in suspension shifted the maxima towards more acidic values, while in the presence of Triton X-100 the position of the zeta potential maxima remained constant. Electroacoustic techniques revealed that a freshly prepared concentrated suspension requires about six hours to equilibrate to achieve a steady zeta potential. Diluting the concentrated suspensions led to decrease of the zeta potential as ions bound to the surface desorbed and screened the surface charge. The zeta potential maxima remained unchanged even after heating the powder in an oven at 200°C (to remove any organic material) thereby suggesting that the most likely explanation for the maxima is isomorphic substitution.

scholarly journals Characterization of salt- and surfactant-containing sandy soil extracts by laser light methods

2015 ◽  
Vol 29 (3) ◽  
pp. 291-298 ◽  
Author(s):  
Szilvia Joó ◽  
Judit Tóth ◽  
Rita Földényi
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Sandy Soil ◽  
Sodium Dodecyl Sulphate ◽  
Colloidal Stability ◽  
Sodium Dodecyl ◽  
Organic Content ◽  
Soil Extracts

Abstract The aim of this work was to study how different salt and surfactant solutions influence the particle size distribution and colloidal stability of sandy soil extracts. Particle size distribution was investigated by the laser diffraction method. Extracts were made from the soil – before and after removing its organic content – with solutions of NaCl or CaCl2 and one cationic and two anionic surfactants. The surfactants influence the particle size distribution of the soil. Due to the use of the NaCl and surfactant mixtures after removal of organic content, the particle sizes increased compared to the extract of the soil. Colloidal stability was investigated by the laser Doppler electrophoresis method resulting in a zeta potential between −5.63 and −23.7 mV, showing that the extracts were rather instable. Static equilibrium experiments with sodium dodecyl sulphate on sandy soil resulted in an L-type of isotherm with three steps, indicating the formation of more surface layers. Comparison of the adsorption isotherm and the measurements of particle size distribution demonstrated that the particle size changes comparably with the formation of the different layers. The zeta potential of the equilibrated solution reached the region of instability and stability when the initial concentration of sodium dodecyl sulphate was near its critical micelle concentration.

scholarly journals Lubrication and Sensory Properties of Emulsion Systems and Effects of Droplet Size Distribution

Foods ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3024
Author(s):  
Qi Wang ◽  
Yang Zhu ◽  
Zhichao Ji ◽  
Jianshe Chen
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Volume Fraction ◽  
Droplet Size Distribution ◽  
Fat Content ◽  
Sensory Properties ◽  
Milk Samples ◽  
Significant Difference ◽  
Emulsion Systems ◽  
Reconstituted Milk

The functional and sensory properties of food emulsion are thought to be complicated and influenced by many factors, such as the emulsifier, oil/fat mass fraction, and size of oil/fat droplets. In addition, the perceived texture of food emulsion during oral processing is mainly dominated by its rheological and tribological responses. This study investigated the effect of droplet size distribution as well as the content of oil droplets on the lubrication and sensory properties of o/w emulsion systems. Friction curves for reconstituted milk samples (composition: skimmed milk and milk cream) and Casein sodium salt (hereinafter referred to as CSS) stabilized model emulsions (olive oil as oil phase) were obtained using a soft texture analyzer tribometer with a three ball-on-disc setup combined with a soft surfaces (PDMS) tribology system. Sensory discrimination was conducted by 22 participants using an intensity scoring method. Stribeck curve analyses showed that, for reconstituted milk samples with similar rheological properties, increasing the volume fraction of oil/fat droplets in the size range of 1–10 µm will significantly enhance lubrication, while for CSS-stabilized emulsions, the size effect of oil/fat droplets reduced to around 1 µm. Surprisingly, once the size of oil/fat droplets of both systems reached nano size (d90 = 0.3 µm), increasing the oil/fat content gave no further enhancement, and the friction coefficient showed no significant difference (p > 0.05). Results from sensory analysis show that consumers are capable of discriminating emulsions, which vary in oil/fat droplet size and in oil/fat content (p < 0.01). However, it appeared that the discrimination capability of the panelist was significantly reduced for emulsions containing nano-sized droplets.

The Effect of Sodium Dodecyl Sulphate (SDS) on Wettability of Different Coals

2013 ◽  
Vol 734-737 ◽  
pp. 513-516 ◽  
Author(s):  
Xiao Yuan Ren ◽  
Zhi Yuan Yang ◽  
Shi Cun Qu ◽  
Jiang Long
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Sodium Dodecyl Sulphate ◽  
Sodium Dodecyl ◽  
Contact Angles ◽  
Coal Rank ◽  
Coal Surface ◽  
Zeta Potentials ◽  
Characterisation Techniques ◽  
Coal Type

Three coals (Jincheng coal, Hancheng coal and Shan-bei coal) varying widely in coal type have been treated with anionic surfactant Sodium Dodecyl Sulphate (SDS). The effect of SDS on wettability of coals was explored by contact angles and zeta potentials characterisation techniques. Results obtained show that the addition of SDS can obviously improve the wettability of coals, and as the coal rank decreases, the wettability increases under investigation. Moreover, the wettability obviously increases with the significant decrease of particle size. The zeta potential for each coal, in the absence of surfactant, is negative, and the potential becomes more negative with the addition of SDS. Meanwhile, the FTIR spectrogram was used to test the changes of-COOH and-OH to analyze the reason for change of wettability, the results show that the wettability changes may be attributed to that the negative active ions of SDS are adsorbed on the coal surface, resulting in the increase of hydrophilic groups of the coal surface.

Grain Refinement in Titanium-Erbium Alloys

1974 ◽  
Vol 32 ◽  
pp. 522-523
Author(s):  
B. B. Rath ◽  
J. E. O'Neal ◽  
R. J. Lederich
Keyword(s):  
Electron Microscopy ◽  
Size Distribution ◽  
Grain Refinement ◽  
Grain Growth ◽  
Volume Fraction ◽  
Pure Titanium ◽  
Systematic Investigation ◽  
Second Phase ◽  
Titanium Matrix ◽  
Average Size

Addition of small amounts of erbium has a profound effect on recrystallization and grain growth in titanium. Erbium, because of its negligible solubility in titanium, precipitates in the titanium matrix as a finely dispersed second phase. The presence of this phase, depending on its average size, distribution, and volume fraction in titanium, strongly inhibits the migration of grain boundaries during recrystallization and grain growth, and thus produces ultimate grains of sub-micrometer dimensions. A systematic investigation has been conducted to study the isothermal grain growth in electrolytically pure titanium and titanium-erbium alloys (Er concentration ranging from 0-0.3 at.%) over the temperature range of 450 to 850°C by electron microscopy.

Sign in / Sign up

Export Citation Format

Share Document