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.

scholarly journals A Comparative Study of the Effect of Different Stabilizers on the Critical Quality Attributes of Self-Assembling Nano Co-Crystals

Pharmaceutics ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 182 ◽  
Author(s):  
Bwalya A. Witika ◽  
Vincent J. Smith ◽  
Roderick B. Walker
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Antiviral Agents ◽  
Sodium Dodecyl ◽  
Quality Attributes ◽  
Polydispersity Index ◽  
Scanning Calorimetry ◽  
Critical Quality Attributes ◽  
X Ray ◽  
Self Assembling

Lamivudine (3TC) and zidovudine (AZT) are antiviral agents used orally to manage HIV/AIDS infection. A pseudo one-solvent bottom-up approach was used to develop and produce nano co-crystals of 3TC and AZT. Equimolar amounts of 3TC dissolved in de-ionized water and AZT in methanol were rapidly injected into a pre-cooled vessel and sonicated at 4 °C. The resultant suspensions were characterized using a Zetasizer. The particle size, polydispersity index and Zeta potential were elucidated. Further characterization was undertaken using powder X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and energy dispersive X-ray spectroscopy scanning electron microscopy. Different surfactants were assessed for their ability to stabilize the nano co-crystals and for their ability to produce nano co-crystals with specific and desirable critical quality attributes (CQA) including particle size (PS) < 1000 nm, polydispersity index (PDI) < 0.500 and Zeta potential (ZP) < −30 mV. All surfactants produced co-crystals in the nanometer range. The PDI and PS are concentration-dependent for all nano co-crystals manufactured while only ZP was within specification when sodium dodecyl sulfate was used in the process.

Effect of Poly(Vinyl Pyrrolidone) on Dispersing Carbon Black Particles

2013 ◽  
Vol 796 ◽  
pp. 432-436
Author(s):  
Xia Yuan
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Carbon Black ◽  
Ultrasonic Method ◽  
Aqueous Media ◽  
Average Particle Size ◽  
Sodium Dodecyl ◽  
Vinyl Pyrrolidone ◽  
Average Particle ◽  
Poly Vinyl Pyrrolidone

The effects of poly (vinyl pyrrolidone)(PVP) on dispersing carbon black (CB) particles were investigated by measuring Z-average particle size, Zeta potential and centrifugal stability of CB dispersions. Addition of PVP in a dispersing medium significantly reduces the size of suspended CB particles, especially in water. The dispersing efficiency of PVP was found to have been enhanced by adding an anionic surfactant, sodium methylenedinaphthalene disulphonate (NNO) in the aqueous media. The particle size of CB dispersed with PVP and NNO was 175.7 nm, significantly smaller than that dispersed with PVP and sodium dodecyl sulfate (SDS). The performance of PVP-encapsulated CB particles and that of PVP-adsorbed CB particles were also compared. The particle size and Zeta potential of PVP-encapsulated CB particles were similar to those of PVP-adsorbed CB particles using ultrasonic method, but the centrifugal stability of PVP-encapsulated CB dispersions was significantly improved. The relative absorbency of PVP/CB dispersions was increased from 42.0% to 63.7%. However, the PVP-encapsulated layer can be destroyed by prolonged ultrasonic treatment because the ultrasound over a long period of time can not only break up the flocculation bridge in the crosslinking matrix of PVP, but also flake off the PVP shells on the surface of CB particles.

Computational Design and Development of Alumina-Nickel Droplet Composites

2016 ◽  
Author(s):  
S. Sohail Akhtar ◽  
A. F. M. Arif ◽  
M. U. Siddiqui ◽  
Kabeer Raza ◽  
L. Taiwo Kareem ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Volume Fraction ◽  
Matrix Material ◽  
Microstructural Analysis ◽  
Computational Design ◽  
Minimum Size

Computational design for property management of composite materials offers a cost sensitive alternate approach in order to understand the mechanisms involved in the thermal and structural behavior of material under various combinations of inclusions and matrix material. The present study is concerned with analyzing the elasto-plastic and thermal behavior of Al2O3-Ni droplet composites using a mean field homogenization and effective medium approximation (EMA) using an in-house code. Our material design approach relies on a method for predicting potential optimum thermal and structural properties for Al2O3-Ni composites by considering the effect of inclusion orientation, volume, size, thermal interface resistance, percolation and porosity. The primary goal for designing such alumina-based composites is to have enhanced thermal conductivity for effective heat dissipation and spreading capabilities. At the same time, other functional properties like thermal expansion coefficient, elastic modulus, and electrical resistivity have to be maintained or enhanced. The optimum volume fraction was found to occur between 15 and 20 vol. %Ni while the average nickel particle size of 5 μm was found a minimum size that will enhance the thermal conductivity. The Young’s modulus was found decreasing as the volume fraction of nickel increases, which would result in enhanced fracture toughness. Electrical conductivity was found to be greatly affected by the percolation phenomenon in the designed range of volume fraction minimum particle size. As a validation, Al2O3 composites with 10% and 15% volume fraction Ni and droplet size of 18 μm are developed using spark Plasma Sintering process. Thermal conductivity and thermal expansion coefficient of the samples are measured to complement the computational design. Microstructural analysis of the sintered samples was also studied using optical microscope to study the morphology of the developed samples. It was found that the present computational design tool was accurate enough in predicting the desired properties of Al2O3-Ni composites.

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 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.

A Model of Nanofluids Thermal Conductivity

2005 ◽  
Author(s):  
Jinbo Wang ◽  
Gang Chen ◽  
Zongqin Zhang
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Zeta Potential ◽  
Volume Fraction ◽  
Ion Concentration ◽  
Research Groups ◽  
New Model ◽  
Conductivity Enhancement ◽  
Temperature Surface ◽  
Suspension Electrolyte

Since the experimental observations were reported that nanofluids exhibit unusually high thermal conductivity, different candidate models have been proposed by several research groups in order to reveal the underlying physics. Despite the efforts, mechanisms of the thermal conductivity enhancement are still being hotly debated. In this paper, we report a new model that correlates nanofluids thermal conductivity to particle size, volume fraction, temperature, surface zeta potential, and suspension electrolyte ion concentration. Our model provides new insights on the mechanisms and guidelines for future experimental exploration.

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 Quality by Design Optimization of Cold Sonochemical Synthesis of Zidovudine-Lamivudine Nanosuspensions

Pharmaceutics ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 367 ◽  
Author(s):  
Bwalya A. Witika ◽  
Vincent J. Smith ◽  
Roderick B. Walker
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Sodium Dodecyl ◽  
In Vitro Cytotoxicity ◽  
Polydispersity Index ◽  
Glycol Succinate ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Cytotoxicity Studies

Lamivudine (3TC) and zidovudine (AZT) are antiviral agents used to manage HIV/AIDS infection. The compounds require frequent dosing, exhibit unpredictable bioavailability and a side effect profile that includes hepato- and haema-toxicity. A novel pseudo one-solvent bottom-up approach and Design of Experiments using sodium dodecyl sulphate (SDS) and α-tocopheryl polyethylene glycol succinate 1000 (TPGS 1000) to electrosterically stablize the nano co-crystals was used to develop, produce and optimize 3TC and AZT nano co-crystals. Equimolar solutions of 3TC in surfactant dissolved in de-ionised water and AZT in methanol were rapidly injected into a vessel and sonicated at 4 °C. The resultant suspensions were characterized using a Zetasizer and the particle size, polydispersity index and Zeta potential determined. Optimization of the nanosuspensions was conducted using a Central Composite Design to produce nano co-crystals with specific identified and desirable Critical Quality Attributes including particle size (PS) < 1000 nm, polydispersity index (PDI) < 0.500 and Zeta potential (ZP) < −30mV. Further characterization was undertaken using Fourier Transform infrared spectroscopy, energy dispersive X-ray spectroscopy, differential scanning calorimetry, powder X-ray diffraction and transmission electron microscopy. In vitro cytotoxicity studies revealed that the optimized nano co-crystals reduced the toxicity of AZT and 3TC to HeLa cells.

Sign in / Sign up

Export Citation Format

Share Document