scholarly journals Dispersions of Metal Oxides in the Presence of Anionic Surfactants

2018 ◽  
Vol 3 (1) ◽  
pp. 3 ◽  
Author(s):  
Leszek Ruchomski ◽  
Edward Mączka ◽  
Marek Kosmulski
Keyword(s):  
Metal Oxides ◽  
Surfactant Concentration ◽  
Critical Concentration ◽  
Supporting Electrolyte ◽  
Sodium Dodecyl ◽  
Sodium Dodecylsulfate ◽  
Solubility Limit ◽  
Ionic Surfactants ◽  
Liquid Ratio ◽  
High Concentration

We studied the behavior of dilute dispersions of nanoparticles of hematite, alumina, and titania in the presence of various concentrations of very pure sodium dodecyl-, tetradecyl-, and hexadecylsulfate. The concentrations studied were up to critical micelle concentration (CMC) for sodium dodecylsulfate, and up to the solubility limit in case of sodium tetradecyl- and hexadecylsulfate. The dispersions were adjusted to different pH (3–11), and 10−3 M NaCl was used as the supporting electrolyte. The solid-to-liquid ratio was strictly controlled in all dispersions, and the behavior of fresh dispersions was compared with dispersions aged for up to eight days. The presence of very low concentrations of ionic surfactants had rather insignificant effects on the ζ potentials of the particles. At sufficient concentrations of ionic surfactants the isoelectric point (IEP) of metal oxides shifted to low pH, and the long-chain surfactants were more efficient in shifting the IEP than their shorter-chain analogues. Once the surfactant concentration reached a critical value, the ζ potentials of the particles reached a pH-independent negative value, which did not change on further increase in the surfactant concentration and/or aging of the dispersion. This critical concentration increases with the solid-to-liquid ratio, and it is rather consistent (for certain oxides and certain surfactants) when it is expressed as the amount of surfactant per unit of surface area. Surprisingly, the surfactant-stabilized dispersions always showed a substantial degree of aggregation; that is, the particle size observed in dispersions by dynamic light scattering was higher than the size of particles observed in dry powders by electron microscopy. Apparently, in spite of relatively high ζ potentials (about 60 mV in absolute value), the surfactant-stabilized dispersions consist of aggregates rather than of primary particles, and in certain dispersions the high concentration of surfactant seems to induce aggregation rather than prevent it.

On the Interaction of Insoluble Alkyl Alcohol Monolayers with Aqueous Solutions of Ionic Surfactants

1980 ◽  
Vol 35 (12) ◽  
pp. 1395-1401
Author(s):  
H.-F. Eicke ◽  
M. K. Sharma
Keyword(s):  
Aqueous Solutions ◽  
Surfactant Concentration ◽  
Critical Concentration ◽  
Sodium Dodecyl ◽  
Ionic Surfactants ◽  
Conductivity Measurements ◽  
Surfactant Aggregates ◽  
Film Balance ◽  
Intermediate Surface ◽  
Alcohol Monolayers

Abstract The interaction between so-called alkyl alcohol (C5-C8) monolayers and aqueous solutions of ionic surfactants with different hydrophilic properties, i.e. calcium di-2-ethylhexyl sulfosuccinate and sodium dodecyl sulfate, has been studied with the help of a Langmuir-Adam film balance. A decrease or increase in surface pressure of the alkyl alcohol monolayers with the addition of surfactants is observed. The shift of the critical concentration (cmc) to increasing surfactant concentration occurs at intermediate surface pressures. This is interpreted as due to the formation of mixed alcohol-surfactant aggregates. The maximum of the cmc as a function of the pressure can be explained by a thermodynamic treatment assuming competition between a pressure dependent solubility of alcohol molecules and the formation of mixed alcohol surfactant complexes. The amount of alkyl alcohol required to react with the surfactant has been evaluated at different surface pressures, which shows values similar to those known from cosurfactant studies in the bulk phase. Critical micelle concentrations of the surfactants were verified by conductivity measurements.

scholarly journals A model of bubble coalescence in the presence of a nonionic surfactant with a low bubble approach velocity

2021 ◽  
Author(s):  
Yuelin Wang ◽  
Huahai Zhang ◽  
Tiefeng Wang
Keyword(s):  
Nonionic Surfactant ◽  
Surfactant Concentration ◽  
Bubble Coalescence ◽  
Bulk Concentration ◽  
High Concentration ◽  
Coalescence Time ◽  
Approach Velocity ◽  
Marangoni Stress ◽  
High Concentrations ◽  
High Concentration Range

A bubble coalescence model for a solution with a nonionic surfactant and with a small bubble approach velocity was developed, in which the mechanism of how coalescence is hindered by Marangoni stress was quantitatively analyzed. The bubble coalescence time calculated for ethanol-water and MIBC-water systems were in good agreement with experimental data. At low surfactant concentrations, the Marangoni stress and bubble coalescence time increased with bulk concentration increase. Conversely, in the high concentration range, the Marangoni stress and coalescence time decreased with bulk concentration. Numerical results showed that the nonlinear relationship between coalescence time and surfactant concentration is determined by the mass transport flux between the film and its interface, which tends to diminish the spatial concentration variation of the interface, i.e., it acts as a “damper”. This damping effect increases with increased surfactant concentration, therefore decreasing the coalescence time at high concentrations.

The effect of surfactant concentration on nanoparticles surface wettability during wettability alteration of oil-wet carbonate rock

2021 ◽  
Vol 15 (2) ◽  
pp. 7993-8002
Author(s):  
Wan Mohd Shaharizuan Mat Latif ◽  
M. S. M. Musa ◽  
A.S.M. Balakirisnan ◽  
W. R. W. Sulaiman
Keyword(s):  
Contact Angle ◽  
Silicon Dioxide ◽  
Carbonate Rock ◽  
Surfactant Concentration ◽  
Sodium Dodecyl ◽  
Particle Surface ◽  
Surface Wettability ◽  
Wettability Alteration ◽  
Inverse Effect ◽  
Sds Surfactant

Previous studies reported that the presence of surfactant increases nanoparticles surface wettability by in-situ surface activation. On the other hand, the excess of surfactant concentration has an inverse effect on particle hydrophobicity by altering it to be hydrophilic back. Hence, this study presents an experimental investigation of wettability alteration by using a surfactant-nanoparticles system by using cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) surfactant, and hydrophilic silicon dioxide (SiO2) and partially hydrophobic silicon dioxide (PH SiO2) nanoparticles. The nanoparticles surface wettability and the wettability alteration of oil-wet carbonate rock were measured by using the contact angle method. The result shows that the contact angle of the oil-wet carbonate rock was most reduced by using CTAB-hydrophilic SiO2, from 112.00o to 28.35o. The excess of surfactant concentration (beyond CMC) shows an inverse effect on particle surface wettability, however, induces the water-wetness of the carbonate rock. Besides, the hydrophilic SiO2 shows a more effective effect as a wettability modifier than the PH SiO2, in the absence and presence of CTAB or SDS surfactant.

Adsorption of surfactants at liquid/vapour and liquid/liquid interfaces

Surfactants ◽  
2019 ◽  
pp. 73-112
Author(s):  
Bob Aveyard
Keyword(s):  
Surfactant Concentration ◽  
Surface Concentration ◽  
Ionic Surfactants ◽  
Thermodynamic Quantities ◽  
Two Dimensional ◽  
Liquid Interfaces ◽  
Surfactant Mixtures ◽  
Surfactant Monolayers ◽  
Solvent Molecules ◽  
The Relationship

The variation of interfacial tension of a solution with surfactant concentration in bulk can be used, in conjunction with the Gibbs adsorption equation, to probe the behaviour of adsorbed surfactant monolayers. An adsorption isotherm equation expresses the relationship between bulk and surface concentrations of surfactant, and is used to determine thermodynamic quantities of surfactant adsorption. The variation of the surface pressure of a surfactant monolayer with the surface concentration is described by a surface equation of state, which reflects something of the nature of a monolayer. The way in which inorganic electrolytes modify the adsorption and monolayer behaviour of ionic surfactants is explained, and adsorption from surfactant mixtures is also introduced. In the Appendix, the discussion is extended to the treatment of adsorbed monolayers as two-dimensional solutions of surfactant with solvent molecules, rather than as two-dimensional gases.

scholarly journals Effect of LiNO3 on Expansion of Alkali–Silica Reaction in Rock Prisms and Concrete Microbars Prepared by Sandstone

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1150 ◽  
Author(s):  
Jinxin Liu ◽  
Lanqing Yu ◽  
Min Deng
Keyword(s):  
Electron Microscope ◽  
Critical Concentration ◽  
Stress Test ◽  
Molar Ratio ◽  
Alkali Silica Reaction ◽  
X Ray Diffraction ◽  
High Concentration ◽  
X Ray ◽  
Long Period ◽  
Scanning Electron

The aim of this research is to investigate the effect of LiNO3 on the alkali–silica reaction (ASR) expansion of reactive sandstone and the mechanism through which this occurs. This paper presents the results from tests carried out on rock prisms and concrete microbars prepared by sandstone and LiNO3. The findings show that LiNO3 does not decrease the expansion of these samples unless the molar ratio of [Li]/[Na + K] exceeds 1.66, and the expansion is greatly increased when its concentration is below this critical concentration. The expansion stress test proves that Li2SiO3 is obviously expansive. X-ray diffraction (XRD) and scanning electron microscope (SEM) results indicate that LiNO3 reacts with the microcrystalline quartz inside sandstone, inhibiting the formation of ASR gel, and the formation of Li2SiO3 causes larger expansion. A high concentration of LiNO3 might inhibit the ASR reaction in the early stages, and the formation of Li2SiO3 causes expansion and cracks in concrete after a long period of time.

Controlling the Pore Size and Connectivity of Alumina-Particle-Stabilized Foams Using Sodium Dodecyl Sulfate: Role of Surfactant Concentration

Langmuir ◽  
2020 ◽  
Vol 36 (35) ◽  
pp. 10331-10340 ◽  
Author(s):  
Yosep Han ◽  
Jiwon Yang ◽  
Minuk Jung ◽  
Seongsoo Han ◽  
Seongmin Kim ◽  
...  
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Pore Size ◽  
Surfactant Concentration ◽  
Alumina Particle ◽  
Sodium Dodecyl ◽  
Dodecyl Sulfate

Self-Inhibition in Ca2+-Evoked Taste Responses: A Novel Tool for Functional Dissection of Salt Taste Transduction Mechanisms

1998 ◽  
Vol 79 (2) ◽  
pp. 911-921 ◽  
Author(s):  
Mamoun A. Kloub ◽  
Gerard L. Heck ◽  
John A. Desimone
Keyword(s):  
Tight Junctions ◽  
Ion Selectivity ◽  
Critical Concentration ◽  
Dependent Manner ◽  
High Concentration ◽  
Salt Taste ◽  
Cation Conductance ◽  
Taste Transduction ◽  
Transduction Mechanisms ◽  
Paracellular Pathways

Kloub, Mamoun A., Gerard L. Heck, and John A. DeSimone. Self-inhibition in Ca2+-evoked taste receptors: a novel tool for functional dissection of salt taste transduction mechanisms. J. Neurophysiol. 79: 911–921, 1998. Rat chorda tympani (CT) responses to CaCl2 were obtained during simultaneous current and voltage clamping of the lingual receptive field. Unlike most other salts, CaCl2 induced negatively directed transepithelial potentials and gave CT responses that were auto-inhibitory beyond a critical concentration. CT responses increased in a dose-dependent manner to ∼0.3 M, whereafter they decreased with increasing concentration. At concentrations where Ca2+ was self-inhibitory, it also inhibited responses to NaCl, KCl, and NH4Cl present in mixtures with CaCl2. Ca2+ completely blocked the amiloride-insensitive component of the NaCl CT response, the entire KCl-evoked CT response, and the high-concentration-domain CT responses of NH4Cl (≥0.3 M). The overlapping Ca2+-sensitivity between the responses of the three Cl− salts (Na+, K+, and NH+ 4) suggests a common, Ca2+-sensitive, transduction pathway. Extracellular Ca2+ has been shown to modulate the paracellular pathways in different epithelial cell lines by decreasing the water permeability and cation conductance of tight junctions. Ca2+-induced modulation of tight junctions is associated with Ca2+ binding to fixed negative sites. This results in a conversion of ion selectivity from cationic to anionic, which we also observed in our system through simultaneous monitoring of the transepithelial potential during CT recording. The data indicate the paracellular pathway as the stimulatory and modulatory site of CaCl2 taste responses. In addition, they indicate that important transduction sites for NaCl, KCl, and NH4Cl taste reception are accessible only through the paracellular pathways. More generally, they show that modulation of paracellular transport by Ca2+ in an intact epithelium has functional consequences at a systemic level.

Evaluation of lipoproteins and apolipoproteins in serum of a Tangier patient by micro-scale two-dimensional electrophoresis.

1987 ◽  
Vol 33 (4) ◽  
pp. 468-472 ◽  
Author(s):  
T Manabe ◽  
S Visvikis ◽  
M F Dumon ◽  
M Clerc ◽  
G Siest
Keyword(s):  
Molecular Mass ◽  
Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Disease Patient ◽  
High Density Lipoproteins ◽  
Two Dimensional ◽  
High Concentration ◽  
Two Dimensional Electrophoresis ◽  
Micro Scale ◽  
Dimensional Electrophoresis

Abstract We examined lipoproteins and apolipoproteins in serum of a Tangier-disease patient. We used three different techniques of micro-scale two-dimensional electrophoresis: (a) no denaturants; (b) with sodium dodecyl sulfate (SDS) used only in the slab gel electrophoresis; (c) and with urea and a detergent used in isoelectric focusing and with SDS in slab gel electrophoresis. By technique a, an extremely low concentration of high-density lipoproteins (HDL) in the Tangier serum was seen, and lipoproteins that cannot form HDL complexes were detected as multiple spots in the acidic (pl 4 approximately 5) and relatively low apparent molecular mass (20,000 approximately 80,000) region. By technique b, Tangier low-molecular-mass lipoproteins were dissociated into their constituent apolipoproteins, and we observed a higher proportion of apoC-III, together with lower proportions of apoA-I and apoA-II, than in the normal HDL fraction. Technique c showed the total content of apolipoproteins in the whole Tangier serum, as several workers have reported. The presence of low-molecular-mass lipoproteins and a high concentration of apoC-III in this lipoprotein fraction characterized the Tangier serum.

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