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1

CHARACTERIZATION OF PHASE AND EMULSION BEHAVIOR, SURFACTANT RETENTION, AND OIL RECOVERY FOR NOVEL ALCOHOL ETHOXYCARBOXYLATE SURFACTANTS  

SciTech Connect

This final technical report describes work performed under DOE Grant No. DE-FG26-97FT97278 during the period October 01, 1997 to August 31, 2001 which covers the total performance period of the project. During this period, detailed information on optimal salinity, temperature, emulsion morphologies, effectiveness for surfactant retention and oil recovery was obtained for an Alcohol Ethoxycarboxylate (AEC) surfactant to evaluate its performance in flooding processes. Tests were conducted on several AEC surfactants and NEODOX (23-4) was identified as the most suitable hybrid surfactant that yielded the best proportion in volume for top, middle, and bottom phases when mixed with oil and water. Following the selection of this surfactant, temperature and salinity scans were performed to identify the optimal salinity and temperature, and the temperature and salinity intervals in which all three phases coexisted. NEODOX 23-4 formed three phases between 4 and 52.5 C. It formed an aqueous rich microemulsion phase at high temperatures and an oleic rich microemulsion phase at low temperatures--a characteristic of the ionic part of the surfactant. The morphology measurement system was set-up successfully at CAU. The best oil/water/surfactant system defined by the above phase work was then studied for emulsion morphologies. Electrical conductivities were measured for middle and bottom phases of the NEODOX 23-4/dodecane/10mM water system and by mixing measured volumes of the middle phase into a fixed volume of the bottom phase and vice versa at room temperature. Electrical conductivity of the mixture decreased as the fraction of volume of the middle phase was increased and vice versa. Also inversion phenomena was observed. These experiments were then repeated for bottom/middle (B/M) and middle/bottom (M/B) conjugate pair phases at 10, 15, 25, 30, 35, 40, and 45 C. Electrical conductivity measurements were then compared with the predictions of the conductivity model developed in this project. The M/B and B/M morphologies and their inversion hysteresis lines conformed to the previously postulated dispersion morphology diagram; that is, within experimental uncertainties, the two emulsion inversion lines in phase volume-temperature space met at a critical point that coincided with the upper critical end point for the phases. Coreflooding measurements were performed by our industrial partner in this project, Surtek, Golden, CO which showed poor hydrocarbon recovery (38.1%) for NEODOX 23-4. It was also found that NEODOX 23-4 surfactant adsorbed too much to the rock (97.1% surfactant loss to the core), a characteristic of the non-ionic part of the surfactant.

Lebone T. Moeti; Ramanathan Sampath

2001-09-28

2

Characterization of Phase and Emulsion Behavior, Surfactant Retention, and Oil Recovery for Novel Alcohol Ethoxycarboxylate Surfactant  

SciTech Connect

Electrical conductivity measurements for middle, bottom, and top phases, as well as bottom/middle, and middle/bottom conjugate pair phases of the NEODOX 23-4/dodecane/10mM water system were continued from the previous reporting period. Electrical conductivity of the mixture decreased as the fraction of volume of the middle phase was increased and vice versa. Also inversion phenomena was observed. Following this, more emulsion studies at various temperatures were progresses. A theoretical model to predict the conductivity measurements using Maxwell equations was developed and sensitivity analyses to test the performance of the model was completed. Surtek, Golden, CO, our industrial partner in this project, investigated the suitability of the surfactant for enhanced oil recovery employing coreflooding techniques and observed lower surfactant and hydrocarbon recovery for NEODOX 23-4.

Moeti, Lebone T.; Sampath, Ramanathan

2002-03-13

3

Emulsion breaking with surfactant recovery  

SciTech Connect

A process useful for recovering surfactant and oil of low water content in surfactant flood oil recovery projects is described. A produced oil-in-water emulsion is treated with brine and partitioning agent, preferably isopropyl alcohol, by mixing and settling to form 3 phases, an oil phase containing a minor amount of surfactant, a partitioning agent phase containing most of the surfactant originally present in the produced emulsion, and a brine phase containing a minor amount of alcohol. 13 claims.

Newcombe, J.

1980-08-05

4

Characterization of Surfactant Free Emulsions  

NASA Astrophysics Data System (ADS)

There is a pharmacological interest in providing a delivery mechanism for highly hydrophobic drugs through the bloodstream. A typical methodology would be to introduce a surfactant which would serve to bind the hydrophobic molecule to the aqueous environment. Because of the need for the surfactant to be non-toxic this avenue proves problematic and many highly hydrophobic drugs which could prove effective are not useable. We have demonstrated the formation of a stable emulsion of Silicone Oil in degassed water alone. The emulsion droplets were on the order of 50 nm in diameter and stable over a period of 8 hours. Previous studies have shown that the surfactant free emulsions do not lose their stability when the previously removed gasses are reintroduced. The formation of a stable emulsion in the complete absence of a surfactant could provide an alternative approach to a physiologically safe drug carrier. The present work involves the formation of stabilized surfactant free emulsions in a homologous series from pentane through decane. The emulsion's structure and thermodynamic stability were then characterized using small angle x-ray scattering.

Brar, Ramaninder; Urquidi, Jacob

2012-10-01

5

Pipeline flow of unstable and surfactant-stabilized emulsions  

Microsoft Academic Search

The literature available on pipeline flow behavior of emulsions is reviewed critically. New results concerning the laminar and turbulent flow behaviors of unstable (without any added surfactant) and surfactant-stabilized water-in-oil emulsions are presented. The unstable emulsions exhibit drag reduction behavior in turbulent flow; the measured friction factors fall well below the values expected on the basis of the laminar flow

Rajinder Pal

1993-01-01

6

Geranyl acetate emulsions: surfactant association structures and emulsion inversion.  

PubMed

Three emulsions of geranyl acetate (GA)-in-water (W) with identical GA/W ratios and varying surfactant (S), Laureth 4, a commercial C(12)EO (4) compound, fractions were investigated for nature and stability. The emulsions with up to 6% surfactant were W/O, as expected with respect to the solubility of the surfactant in the oil. At 10% surfactant, the aqueous phase became the continuous one and the apparent stability of the emulsion was significantly enhanced. Analysis of the phase diagram and experimental evidence showed the high water content emulsion to be a liquid crystal-in-water emulsion; a kind that did not change even at extreme O/W and LC/W ratios. PMID:19409570

Friberg, Stig E; Al-Bawab, Abeer; Bozeya, Ayat; Aikens, Patricia A

2009-04-02

7

Investigation of Phase and Emulsion Behavior, Surfactant Retention and Condensate Recovery for Condensate/Water/Ethanol Mixtures  

SciTech Connect

This semi-annual technical progress report describes work performed at Morehouse College under DOE Grant No. DE-FG26-02NT15447 during the period April 01, 2004 to September 30, 2004 which covers the fourth six months of the project. Presently work is in progress to characterize phase and emulsion behavior for ethylbenzene/water/ethanol system. Ethylbenzene that has the equivalent carbon number is used as the model condensate. During this reporting period, work was under way and the electrical conductivity experimental system was set up at the Atlanta University Center. Following the set-up of the emulsion measurement system, the electronic instruments and data acquisition modules involved were tested for proper operation of the system. Then, the conductivity output was normalized with that obtained for 10mM NaCl water. Radial coreflooding experiments with ethanol injection prior to and after water injection were completed to assess the effectiveness of the surfactant flooding in the recovery of condensate by our industrial partner, Surtek, CO, in this reporting period. In Run 1, 10 mM NaCl without ethanol injection recovered 31.5% of the initial ethyl benzene saturation. Injection of ethanol following 10 mM NaCl produced a tertiary ethyl benzene bank with maximum ethyl benzene cuts of 32%. In Run 2, 50 vol% of pure (100%) ethanol was injected and flowed through the Berea sandstone after Ethyl Benzene Saturation. 69% of the initial ethyl benzene was recovered. Results of the radial corefloods are very encouraging. Emulsion conductivity measurements for conjugate pair phases are in progress at Morehouse.

Ramanathan Sampath

2004-09-30

8

Investigation of Phase and Emulsion Behavior, Surfactant Retention and Condensate Recovery for Condensate/Water/Ethanol Mixtures  

SciTech Connect

This semi-annual technical progress report describes work performed at Morehouse College under DOE Grant No. DE-FG26-02NT15447 during the period October 01, 2003 to March 31, 2004 which covers the third six months of the project. Presently work is in progress to characterize phase and emulsion behavior for ethylbenzene/water/ethanol system. Ethylbenzene that has the equivalent carbon number is used as the model condensate. During this reporting period, temperature scans were performed mixing equal volumes of ethylbenzene and 10mM NaCl water with various concentrations of ethanol ranging from 2 to 70 vol%. For the range of temperatures tested (2 to 70 C), results indicate that temperature is invariant and produced a single phase for ethanol concentrations greater than 60 vol%. For ethanol concentrations less than 60 vol%, only two phases were obtained with aqueous rich bottom phase more in volume than that of the ethylbenzene rich top phase. Linear coreflooding experiments were completed by our industrial partner in this project, Surtek, CO, to measure the condensate recovery in flooding processes. It was found about 30% ethylbenzene recovery was obtained by the waterflooding, however, 2wt% ethanol flooding did not produce incremental recovery of the ethylbenzene. Radial coreflooding with ethanol injection prior to water injection is in progress to assess the effectiveness of the surfactant flooding in the recovery of condensate.

Ramanathan Sampath

2004-03-31

9

INVESTIGATION OF PHASE AND EMULSION BEHAVIOR, SURFACTANT RETENTION, AND CONDENSATE RECOVERY FOR CONDENSATE/WATER/ETHANOL MIXTURES  

SciTech Connect

This semi-annual technical progress report describes work performed at Morehouse College under DOE Grant No. DE-FG26-02NT15447 during the period April 01, 2003 to September 30, 2003 which covers the second six months of the project. Presently work is in progress to characterize phase and emulsion behavior for ethylbenzene/water/ethanol system. During this reporting period, salinity scans were completed for 0, 5, 10, 20, 50, 100, 250, 500, and 1000 mM salt concentrations at room temperature to identify optimal salinity intervals in which all three phases coexist for this system. Temperature scans are in progress at Morehouse College to identify the optimal temperature, and the temperature intervals in which all three phases coexist for this system. Coreflooding experiments are being conducted by our industrial partner in this project, Surtek, CO, to measure the effectiveness for surfactant retention and condensate recovery in flooding processes. Review of the current literature in the subject area, and modeling efforts that were established in our previous studies to predict electrical conductivities and inversion phenomena was continued from the previous reporting period. Based on the review a computer model to predict electrical conductivities of the ethylbenzene (that has the equivalent carbon number of the condensate)/water/ethanol system is being developed.

Ramanathan Sampath

2003-10-01

10

Investigation of Phase and Emulsion Behavior, Surfactant Retention and Condensate Recovery for Condensate/Water/Ethanol Mixtures  

SciTech Connect

This semi-annual technical progress report describes work performed at Morehouse College under DOE Grant No. DE-FG26-02NT15447 during the period October 01, 2002 to April 01, 2003 which covers the first six months of the project. Presently work is in progress to characterize phase and emulsion behavior for condensate/water/ethanol system. Temperature and salinity scans are planned to identify the optimal salinity and temperature, and the temperature and salinity intervals in which all three phases coexist for this system. Test matrix to perform salinity and temperature scans has been established. Supply requests to obtain hydrocarbons, surfactant, etc., were processed and supplies obtained. Current literature in the subject area, and modeling efforts that were established in our previous studies to predict electrical conductivities and inversion phenomena were reviewed. Based on the review a computer model to predict electrical conductivities of the ethylbenzene (that has the equivalent carbon number of the condensate)/water/ethanol system is being developed. These activities resulted in one published conference abstract during this reporting period.

Ramanathan Sampath

2003-03-31

11

INVESTIGATION OF PHASE AND EMULSION BEHAVIOR, SURFACTANT RETENTION, AND CONDENSATE RECOVERY FOR CONDENSATE/WATER/ETHANOL MIXTURES  

SciTech Connect

This final technical report describes work performed at Morehouse College under DOE Grant No. DE-FG26-02NT15447 during the period October 01, 2002 to September 30, 2005, which covers the total performance period of the project. During this period, work was conducted to characterize phase and emulsion behavior for ethylbenzene/water/ethanol system. Ethylbenzene that has the equivalent carbon number was used as the model condensate. Salinity scans were performed for 0, 5, 10, 20, 50, 100, 250, 500, and 1000 mM salt concentrations at room temperature to identify the optimal salinity and salinity intervals in which all phases coexisted. It was found that only two phases formed, and salinity has no significant effect in the volumes of the phases formed. Experiments were repeated at 30 C and observed salinity has no effect at higher temperatures as well. Following the salinity experiments, measurements were made with 10mM NaCl water for surfactant concentrations from 2 to 70 volume percent at room temperature. It was found that only two phases were formed upto 60 vol% concentration of the surfactant. Above 60 vol% surfactant, the mixture produced only a single phase. Experiments were repeated from 2 to 70 C and observed that temperature has no significant effect on the number of phases formed. At the temperatures and surfactant concentration tested, volume fraction of the aqueous bottom phase was found to be larger than that of the top phase. Electrical conductivity measurements were then conducted for bottom/top, and top/bottom conjugate pair phases of the ethylbenzene/water/ethanol system formed by mixing ethanol at various volume percentages including 2,10,33,and 56% while keeping the volumes of ethylbenzene and water the same in the mixture. Electrical conductivity of the bottom phase decreased as ethanol volume fraction in the mixture increased. Conductivity of the top phase was found small and remained almost the same for variations in ethanol volume fraction in the mixture. Also inversion phenomena was observed. Prediction of the conductivity data obtained was then conducted employing a theoretical model developed in this project based on Maxwell relations. Results of the comparisons for 2, 10, 33, and 56% ethanol volume in the mixture are presented here. A good agreement was obtained between the predicted emulsion conductivities and the measured values. Work was also conducted at Surtek, Golden, CO, our industrial partner in this project, to measure the effectiveness for condensate recovery employing coreflooding techniques. In Run 1 of the radial coreflooding experiments conducted, 10 mM NaCl without ethanol injection recovered 31.5% of the initial ethyl benzene saturation. Injection of ethanol following 10 mM NaCl produced a tertiary ethyl benzene bank with maximum ethyl benzene cuts of 32%. In Run 2, 50 vol% of pure (100%) ethanol was injected and flowed through the Berea sandstone after Ethyl Benzene Saturation. 69% of the initial ethyl benzene was recovered. While 50 vol% of ethanol injection does not make economic sense when injecting a large fraction of a pore volume, injection of sufficient volume to remove water and condensate from around the near well bore area of a gas well could be economic.

Ramanathan Sampath

2005-12-01

12

Surface deposition and phase behavior of oppositely charged polyion-surfactant ion complexes. Delivery of silicone oil emulsions to hydrophobic and hydrophilic surfaces.  

PubMed

The adsorption from mixed polyelectrolyte-surfactant solutions at hydrophobized silica surfaces was investigated by in situ null-ellipsometry, and compared to similar measurements for hydrophilic silica surfaces. Three synthetic cationic copolymers of varying hydrophobicity and one cationic hydroxyethyl cellulose were compared in mixtures with the anionic surfactant sodium dodecylsulfate (SDS) in the absence or presence of a dilute silicone oil emulsion. The adsorption behavior was mapped while stepwise increasing the concentration of SDS to a polyelectrolyte solution of constant concentration. The effect on the deposition of dilution of the bulk solution in contact with the surface was also investigated by gradual replacement of the bulk solution with 1 mM aqueous NaCl. An adsorbed layer remained after complete exchange of the polyelectrolyte/surfactant solution for aqueous NaCl. In most cases, there was a codeposition of silicone oil droplets, if such droplets were present in the formulation before dilution. The overall features of the deposition were similar at hydrophobic and hydrophilic surfaces, but there were also notable differences. SDS molecules adsorbed selectively at the hydrophobized silica surface, but not at the hydrophilic silica, which influenced the coadsorption of the cationic polymers. The largest amount of deposited material after dilution was found for hydrophilic silica and for the least-hydrophobic cationic polymers. For the least-hydrophobic polyions, no significant codeposition of silicone oil was detected at hydrophobized silica after dilution if the initial SDS concentration was high. PMID:21667982

Clauzel, Maryline; Johnson, Eric S; Nylander, Tommy; Panandiker, Rajan K; Sivik, Mark R; Piculell, Lennart

2011-06-27

13

Investigation of Phase and Emulsion Behavior, Surfactant Retention and Condensate Recovery for Condensate/Water/Ethanol Mixtures  

SciTech Connect

This semi-annual technical progress report describes work performed at Morehouse College under DOE Grant No. DE-FG26-02NT15447 during the period April 01, 2005 to September 30, 2005 which covers the sixth six months of the project. Presently work is in progress to characterize phase and emulsion behavior for ethylbenzene/water/ethanol system. Ethylbenzene that has the equivalent carbon number is used as the model condensate. In the last reporting period, electrical conductivity measurements for bottom/top, and top/bottom conjugate pair phases of the ethylbenzene/water/ethanol system were performed for various ethanol volume percentage in the mixture: 2,10,20,33,43,50, and 56. During this reporting period, prediction of electrical conductivity data obtained in the past was conducted employing a theoretical model already developed in this project. Results of the comparisons for 2, and 10% ethanol volume in the mixture are presented here. A good agreement was obtained between the predicted emulsion conductivities and the measured values. To date about 99% of the proposed work has been completed. Conductivity prediction for 56% ethanol volume in the mixture is in progress. Following this prediction, a final report will be developed describing the research activities conducted through the entire project period including results and conclusions.

Ramanathan Sampath

2005-09-30

14

Investigation of Phase and Emulsion Behavior, Surfactant Retention and Condensate Recovery for Condensate/Water/Ethanol Mixtures  

SciTech Connect

This semi-annual technical progress report describes work performed at Morehouse College under DOE Grant No. DE-FG26-02NT15447 during the period October 01, 2004 to March 31, 2005 which covers the fifth six months of the project. Presently work is in progress to characterize phase and emulsion behavior for ethylbenzene/water/ethanol system. Ethylbenzene that has the equivalent carbon number is used as the model condensate. During this reporting period, electrical conductivity measurements for bottom, and top phases, as well as bottom/top, and top/bottom conjugate pair phases of the ethylbenzene/water/ethanol system were performed for various ethanol volume percentage of the mixtures starting from 2% to 60%. Preliminary findings are that electrical conductivity of the bottom phase decreased as ethanol volume fraction of the mixture increased. Conductivity of the top phase was small and remained almost the same for variations in ethanol volume fraction of the mixture. Conductivity of the emulsion of the conjugate pair phases decreased as the fraction of volume of the top phase was increased and vice versa. Also inversion phenomena was observed. Detailed analyses are in progress including the prediction of conductivity data using the theoretical model already developed in this project.

Ramanathan Sampath

2005-03-31

15

Method of extracting and reutilizing surfactants from emulsions  

SciTech Connect

This is a claim for extracting surfactants from produced emulsions of oil, water and surfactant and concentrating the surfactants into a relatively small volume, emulsion phase that can be reutilized in surfactant flooding. The two phases left behind in the extraction are a substantially water-free and surfactant-free crude oil phase and an oil-free aqueous phase. The extracting compounds employed are the alkali metal salts and ammonium salts of cumene sulfonate, propyl benzene sulfonate, ethyl benzene sulfonate, methyl ethyl benzene sulfonate, diethyl benzene sulfonate, methyl propyl benzene sulfonate, xylene sulfonate and dicyclopentadiene sulfonate.

Maddox, J. Jr.

1985-04-30

16

Gemini Surfactant as a New “Green” Demulsifier for Treating Oilfield Emulsions  

Microsoft Academic Search

Surface tension and interfacial tension (IFT) were the key factors asso- ciated with the stability of crude oil emulsion. Investigation of interfacial tension behavior related with the demulsification of crude oil emulsions can have a great impact on the development of crude oil demulsification processes and products. This article presents the surface and interface behaviors of Gemini surfactants (12-2-12, (12)-2-(12),

Z. Huang; H. Lu; T. Zhang; R. Wang; D. Qing

2010-01-01

17

Thermodynamically stable emulsions using janus dumbbells as colloid surfactants.  

PubMed

One of the most important properties of emulsions is their stability. Most emulsions stabilized with molecular surfactants tend to lose their stability over time via different mechanisms. Although the stability of emulsions stabilized with homogeneous particles have been shown to be superior to that of surfactant-stabilized emulsions, these Pickering emulsions nevertheless are only kinetically stable and thus can undergo destabilization. Janus particles that have two opposite wetting surfaces have shown promise in imparting emulsions with long-term stability because of their strong attachment to the oil-water interface. In this theoretical study, we consider thermodynamics of emulsion stabilization using amphiphilic Janus dumbbells, which are nonspherical particles made of two partially fused spherical particles of opposite wettability. These amphiphilic dumbbells are attractive candidates as colloid surfactants for emulsion stabilization because highly uniform Janus dumbbells can be synthesized in large quantities; thus, their application in emulsion stabilization can become practical. Our theoretical calculation demonstrates that Janus dumbbells can indeed generate thermodynamically stable Pickering emulsions. In addition, we also find that there exists a total oil-water interfacial area that results in the lowest energy state in the system, which occurs when Janus dumbbells available in the system are completely consumed to fully cover the droplet interfaces. We show that the geometry of dumbbells as well as the composition of the emulsion mixtures has significant influences on the average size of dumbbell-stabilized emulsions. We also investigate the effect of asymmetry of Janus dumbbells on the average droplet radius. Our results clearly show that amphiphilic Janus dumbbells provide unique opportunities in stabilizing emulsions for various applications. PMID:24044808

Tu, Fuquan; Park, Bum Jun; Lee, Daeyeon

2013-10-02

18

Crude oil emulsions containing a compatible fluorochemical surfactant  

SciTech Connect

This patent describes a crude oil in water emulsion, which is stable to both breakdown and phase inversion up to at least about 50{degrees} C., the emulsion containing an effective, compatible, emulsion stabilizing amount of a fluorochemical surfactant of the formula (R{sub {ital f}}){sub {ital n}}A{sub {ital m}}Q wherein R{sub {ital f}} is an inert, stable, oleophobic and hydrophobic fluoroaliphatic group having up to about 20 carbon atoms; n is an integer from 1 to 3; A is a direct bond or an organic linking group and is covalently bonded to both R{sub {ital f}} and Q; Q is an anionic, nonionic or amphoteric group; and m is an integer from 1 to 3; wherein the amount of weight of the fluorochemical surfactant present in the emulsion being between about 0.001 and 1% by weight of the emulsion, in the presence of absence of up to about 2% by weight of a crude oil emulsion promoting hydrocarbon surfactant, with the proviso that at least about 0.005% by weight total fluorochemical and hydrocarbon surfactant is present, based upon the weight of emulsion, and wherein the emulsion contains bout 15 to about 90 percent by weight water, based upon the weight of emulsion, such that the viscosity of the emulsion is less than about 50% of the viscosity of the crude oil, and wherein the emulsion spontaneously breaks down into an aqueous and crude oil phase at a temperature between about 55{degrees} and 75{degrees} C.

Karydas, A.; Rodgers, J.

1991-02-19

19

Double emulsions stabilized by macromolecular surfactants  

Microsoft Academic Search

Multiple emulsions are emulsions within emulsions, stabilized traditionally by monomeric emulsifiers both at the inner and outer interface.Double emulsions are thermodynamically unstable and fast coalescence, as well as fast release of markers and drugs, have been the main drawbacks of this technology.Polymeric synthetic emulsifiers, as well as natural macromolecules in combination with monomeric emulsifiers, have recently been studied and evaluated.The

Nissim Garti; Abraham Aserin

1996-01-01

20

Binding of Rhizomucor miehei lipase to emulsion interfaces and its interference with surfactants  

Microsoft Academic Search

Interactions between Rhizomucor miehei lipase and emulsion droplets were studied in oil-in-water emulsions. The emulsions were stabilized by either the cationic surfactant didodecyldimethylammonium bromide, the anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate or the non-ionic surfactant 1-(2-ethylhexyl)-3-(2-ethylbutyl)-2-hexaethylene glycerol ether. By measuring the mobility of the emulsion droplets it was shown that the lipase bound to droplets stabilized by the cationic surfactant, but not

Peter Skagerlind; Mikael Jansson; Björn Bergenståhl; Karl Hult

1995-01-01

21

Creaming of emulsions: the role of depletion forces induced by surfactant  

Microsoft Academic Search

We show that excess surfactant, or salt, in the bulk phase of an oil in water ionic emulsion has strong consequences on the thermodynamical behavior of the dispersion. Static light scattering experiments have been performed to investigate the attractive interaction induced by micelles according to a depletion mechanism. This interaction can be largely reduced by adding salt. This depletion interaction

J. Bibette; D. Roux; B. Pouligny

1992-01-01

22

Foam, emulsion and wetting films stabilized by polyoxyalkylated diethylenetriamine (DETA) polymeric surfactants.  

PubMed

This review explores three (A, B, C) polyoxyalkylated diethylenetriamine (DETA) polymeric surfactants belonging to the group of star-like polymers. They have a similar structure, differing only in the number of polymeric branches (4, 6 and 9 in the mentioned order). The differences in these surfactants' ability to stabilize foam, o/w/o and w/o/w emulsion and wetting films are evaluated by a number of methods summarized in Section 2. Results from the studies indicate that differences in polymeric surfactants' molecular structure affect the properties exhibited at air/water, oil/water and water/solid interfaces, such as the value of surface tension, interfacial tension, critical micelle concentration, degree of hydrophobicity of solid surface, etc. Foam, emulsion and wetting films stabilized by such surfactants also show different behavior regarding some specific parameters, such as critical electrolyte concentration, surfactant concentration for obtaining a stable film, film thickness value, etc. These observations give reasons to believe that model studies can support a comprehensive understanding of how the change in polymeric surfactant structure can impact thin liquid films properties. This may enable a targeted design of the macromolecular architecture depending on the polymeric surfactants application purpose. PMID:21807358

Khristov, Khr; Petkova, H; Alexandrova, L; Nedyalkov, M; Platikanov, D; Exerowa, D; Beetge, J

2011-07-21

23

Perfluoroalkylated telomers derived from tris(hydroxymethyl)acrylamidomethane as surfactants and co-surfactants in fluorocarbon emulsions  

Microsoft Academic Search

The ability of perfluoroalkylated telomers derived from tris(hydroxymethyl)acrylamidomethane (TAC) to stabilize fluorocarbon emulsions has been investigated. For this purpose, 50% w\\/v emulsions of perfluorodecalin (FDC) and perfluoro-octyl bromide (PFOB) were prepared with a total 3% w\\/v of surfactant and were compared with emulsions prepared with Pluronic F-68® or egg yolk phospholipids (EYP). When used as the sole surfactant, telomers 1

Evelyne Myrtil; Leila Zarif; Jacques Greiner; Jean G. Riess; Bernard Pucci; André A. Pavia

1995-01-01

24

Experimental Investigation of Rheological and Morphological Properties of Water in Crude Oil Emulsions Stabilized by a Lipophilic Surfactant  

Microsoft Academic Search

Rheological behavior of two crude oils and their surfactant-stabilized emulsions with initial droplet sizes ranging from 0.5 to 75 µm were investigated at various temperatures under steady and dynamic shear testing conditions. In order to evaluate the morphology and Stability of emulsions, microscopic analysis was carried out over three months and average diameter and size distribution of dispersed droplets were determined.

Mohammad Bagher Sadeghi; Ahmad Ramazani S. A; Vahid Taghikhani; Cyrus Ghotbi

2012-01-01

25

Preparation characteristics of oil-in-water emulsions using differently charged surfactants in straight-through microchannel emulsification  

Microsoft Academic Search

Straight-through microchannel (MC) emulsification is a novel technique for producing monodisperse emulsions using a silicon array of micromachined through-holes, named a straight-through MC. This paper investigates the effect of surfactants on the straight-through MC emulsification behavior. The oblong straight-through MC used in this study had channel lengths of 48.7 and 9.6?m. Using anionic and nonionic surfactants, monodisperse soybean oil-in-water (O\\/W)

Isao Kobayashi; Mitsutoshi Nakajima; Sukekuni Mukataka

2003-01-01

26

The relevance HLB of surfactants on the stability of asphalt emulsion  

Microsoft Academic Search

In this study, 13 non-ionic surfactants were selected; they have been used in wide range of HLB from 4 to 17.6. Asphalt emulsions with individual and some mixtures of surfactants were done. The stability of emulsions was determined via three physical means, batch settling time, particle size analysis and rheological characterization. The optimum stability of w\\/o emulsions was obtained at

Ahmed M. Al-Sabagh

2002-01-01

27

Rheological and dielectric behavior of electrorheological emulsions  

Microsoft Academic Search

The rheological and dielectric behavior of electrorheological (ER) emulsions composed of silicone oil (continuous phase) and two chlorinated paraffins (dispersed phase) are studied in this work. The chlorinated paraffins have different permittivity and conductivity values, and both are more conducting than the silicone oil. The rheological behavior of the emulsions is analyzed under constant dc electric fields, for two chlorinated

L Rejon; B Ortiz-Aguilar; H de Alba; O Manero

2004-01-01

28

Method of extracting and reutilizing surfactants from emulsions using sulfonated alkyl benzenes and ethoxylated phenols  

SciTech Connect

The disclosed invention is a one step or two step process for extracting surfactant from produced emulsions of oil, water and surfactants, concentrating the surfactants into a relatively small volume emulsion middle phase that can be reutilized in surfactant flooding and separating substantial quantities of salable oil from the emulsions. In the two step process, a sulfonated alkyl benzene is added and mixed with the emulsions, which partitions upon settlement into three phases, a clean oil phase, a first microemulsion middle phase and an aqueous phase. An ethoxylated phenol is then added and mixed to the first middle phase to yield at least two more similar phases with the middle phase containing the concentrated surfactants. Alternately, the sulfonated alkyl benzene and the ethoxylated phenol can be combined and added in a one step extraction process.

Maddox Jr., J.; Schievelbein, V. H.

1985-05-21

29

Breaking crude oil emulsions by the action of surfactants  

SciTech Connect

The mechanisms through which interfacial structures become stronger as time passes and are disrupted by the action of a surfactant have been studied by means of a ''falling spheres'' technique. This technique is used in this paper to establish a number of relationships governing the action of water-soluble and oil-soluble demulsifiers on the interfacial films. The fact that different demulsifiers require different lengths of time to break up interfacial films; the breaking time; the film strength that various distances from the point of demulsifier introduction; the susceptibility of carboniferous crudes to demulsifier I; the hypothesis of the need for suppressing the activity of natural emulsifers; and the mechanisms of emulsion destablization--all of these aspects of demulsifier action are studied.

Tronov, V.P.

1983-07-01

30

Particle size reduction of emulsions by formulation design-II: effect of oil and surfactant concentration.  

PubMed

The objective of this study was to investigate the effect of the concentration of surfactant and oil on particle size reduction and stability of oil-in-water emulsion formulations containing polyhydroxy alcohols. Emulsions were prepared using an emulsifier system consisting of Tween 80 and Span 80 with 5%, 10%, 15% and 20% soybean oil and containing 50% w/w of either propylene glycol (PG) or glycerol (GLY) in the external phase. At each oil concentration, four emulsions were formulated with increasing surfactant concentration to provide emulsions with surfactant to oil (S/O) ratios of 0.1, 0.2, 0.3 and 0.4. Three parameters were evaluated, particle size reduction, particle size stability upon dilution, and viscosity. It was found that increase in S/O ratio resulted in substantial decrease in particle size in all cases. But there was a difference in the particle size reduction pattern between PG and GLY. Increase in oil concentration at the same S/O ratio caused particle size reduction for emulsions with PG but not for emulsions with GLY. The reduction in particle size was also greater for emulsions containing PG. Further, particle size of emulsions containing PG was found to be stable over 24 hours after dilution. However, a slight increase in particle size was observed in emulsions containing GLY. It was also found that the viscosity of emulsions increased with an increase S/O ratio as well as the concentration of the oil. PMID:7780748

Chanana, G D; Sheth, B B

31

Kinetics of swelling–breakdown of a W\\/O\\/W multiple emulsion: possible mechanisms for the lipophilic surfactant effect  

Microsoft Academic Search

The properties and behavior of a W\\/O\\/W multiple emulsion formulation were analyzed during a swelling–breakdown process. Various experimental analyses, such as granulometry, rheology and conductimetry were performed, as well as a micropipette aspiration method. The predominant role of the lipophilic surfactant during the swelling phase was confirmed. Two different mechanisms can be proposed. Both imply the migration of the lipophilic

S. Geiger; S. Tokgoz; A. Fructus; N. Jager-Lezer; M. Seiller; C. Lacombe; J.-L. Grossiord

1998-01-01

32

Synergistic stabilization of perfluorocarbon-pluronic F-68 emulsion by perfluoroalkylated polyhydroxylated surfactants  

Microsoft Academic Search

One of the most serious limitations of the first generation of fluorocarbon emulsions destined to serve as injectable oxygen\\u000a carriers (blood substitutes) is their insufficient, stability. Considerable stabilization of such emulsions has now been achieved\\u000a by using a combination of Pluronic F-68, a polyoxyethylene polyoxypropylene block polymer, and of a perfluoroalkylated polyhydroxylated\\u000a surfactant (PPFS) comprising a C6F13 or C8F17 fluorophilic

Leila Zarif; Alexandre Manfredi; Christian Varescon; Maurice Le Blanc; Jean G. Riess

1989-01-01

33

Asphalt emulsions: experimental study of the cationic surfactant adsorption at the asphalt-water interface  

Microsoft Academic Search

Cationic asphalt-in-water emulsions are widely used for road construction and surfacing. These systems are an interesting\\u000a model for the basic study of emulsions because the high asphalt viscosity allows the system to afford some perturbations without\\u000a readily producing coalescence. The adsorption of a cationic surfactant, an octadecyl-propylene-diamine, at asphalt-water interface\\u000a is investigated. The adsorption isotherm was determined using two different

J. E. Poirier; M. Bourrel; P. Castillo; C. Chambu; M. Kbala

34

Rheology properties of glucopyranoside stabilized oil–water emulsions: effect of alkyl chain length and bulk concentration of the surfactant  

Microsoft Academic Search

Effect of the alkyl chain length and concentration of the surfactant on Rheology properties of O\\/W emulsions stabilized with homologues series of glucopyranoside was studied. The Rheology properties in turn are being used to describe emulsion structure, emulsifying effect and emulsion stability. The emulsifying property was also explored through interfacial tension measurement. The homologues series of glucopyranoside possess identical polar

Boris Niraula; Tan Cok King; Tham Kok Chun; Misni Misran

2004-01-01

35

Preparation and power consumption of surfactant–fuel oil–water emulsions using axial, radial, and mixed flow impellers  

Microsoft Academic Search

Surfactant–oil–water emulsions could have applications in enhanced oil recovery and the bio-desulfurization process applied to crude oil and some fractions. A simple way to prepare oil in water (O\\/W) emulsions is using a tank and an agitation device. The aim of this work is to propose a technology to prepare surfactant–fuel oil–water emulsions by means of a system involving a

Luis G Torres; Edmundo R Zamora

2002-01-01

36

Physical Properties and Biological Activity of Poly(butyl acrylate-styrene) Nanoparticle Emulsions Prepared with Conventional and Polymerizable Surfactants  

PubMed Central

Recent efforts in our laboratory have explored the use of polyacrylate nanoparticles in aqueous media as stable emulsions for potential applications in treating drug-resistant bacterial infections. These emulsions are made by emulsion polymerization of acrylated antibiotic compounds in a mixture of butyl acrylate and styrene (7:3 w:w) using sodium dodecyl sulfate (SDS) as a surfactant. Prior work in our group established that the emulsions required purification to remove toxicity associated with extraneous surfactant present in the media. This paper summarizes our investigations of poly(butyl acrylate-styrene) emulsions made using anionic, cationic, zwitterionic, and non-charged (amphiphilic) surfactants, as well as attachable surfactant monomers (surfmers), comparing the cytotoxicity and microbiological activity levels of the emulsion both before and after purification. Our results show that the attachment of a polymerizable surfmer onto the matrix of the nanoparticle neither improves nor diminishes cytotoxic or antibacterial effects of the emulsion, regardless of whether the emulsions are purified or not, and that the optimal properties are associated with the use of the non-ionic surfactants versus those carrying anionic, cationic, or zwitterionic charge. Incorporation of an N-thiolated ?-lactam antibacterial agent onto the nanoparticle matrix via covalent attachment endows the emulsion with antibiotic properties against pathogenic bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), without changing the physical properties of the nanoparticles or their emulsions.

Garay-Jimenez, Julio C.; Gergeres, Danielle; Young, Ashley; Dickey, Sonja; Lim, Daniel V.; Turos, Edward

2009-01-01

37

The role of non-ionic surfactants in emulsion stability  

Microsoft Academic Search

The role of W, aryl polyglycol ester, and G 100P, an alkyl phenyl polyglycol ether, on the stability of dilute petroleum ether in water\\u000a emulsion has been studied in the light of the DLVO theory. The zeta potential of the emulsions flocculated by varying concentrations\\u000a of different electrolytes, viz., potassium nitrate, strontium nitrate and aluminium ammonium sulphate, has been calculated

A. Kamel; V. Sabet; H. Sadek; S. N. Srivastava

38

Direct Numerical Simulation of Surfactant-Stabilized Emulsions Morphology and Shear Viscosity in Starting Shear Flow  

SciTech Connect

A 3D lattice Boltzmann model for two-phase flow with amphiphilic surfactant was used to investigate the evolution of emulsion morphology and shear stress in starting shear flow. The interfacial contributions were analyzed for low and high volume fractions and varying surfactant activity. A transient viscoelastic contribution to the emulsion rheology under constant strain rate conditions was attributed to the interfacial stress. For droplet volume fractions below 0.3 and an average capillary number of about 0.25, highly elliptical droplets formed. Consistent with affine deformation models, gradual elongation of the droplets increased the shear stress at early times and reduced it at later times. Lower interfacial tension with increased surfactant activity counterbalanced the effect of increased interfacial area, and the net shear stress did not change significantly. For higher volume fractions, co-continuous phases with a complex topology were formed. The surfactant decreased the interfacial shear stress due mainly to advection of surfactant to higher curvature areas. Our results are in qualitative agreement with experimental data for polymer blends in terms of transient interfacial stresses and limited enhancement of the emulsion viscosity at larger volume fractions where the phases are co-continuous.

Roar Skartlien; Espen Sollum; Andreas Akselsen; Paul Meakin

2012-07-01

39

Method of extracting and reutilizing surfactants from emulsions with sulfonated alkyl benzenes and alcohols  

SciTech Connect

Disclosed is a method for extracting surfactants from produced emulsions of oil, water and surfactant and concentrating the surfactants into a relatively small volume, surfactant-rich, middle phase that can be reutilized in surfactant flooding. A first extraction is performed with an aqueous solution of a first extracting compound, which yields three phases after separation, a substantially water-free and surfactant-free crude oil phase, a first surfactant-rich middle phase and an oil-free aqueous phase. The first extracting compounds employed are the alkali metal salts and ammonium salts of cumene sulfonate, propyl benzene sulfonate, ethyl benzene sulfonate, methyl ethyl benzene sulfonate, diethyl benzene sulfonate, methyl propyl benzene sulfonate, xylene sulfonate and dicyclopentadiene sulfonate. A second extraction is then performed by mixing a second extracting compound with the first middle phase, which yields three phases after separation, a water-free and surfactant-free oil phase, a second surfactant-rich middle phase and an oil-free aqueous phase. The second extracting compound is a alkanol having two to four carbon atoms.

Maddox Jr., J.

1985-05-14

40

Effect of ionic surfactants on drainage and equilibrium thickness of emulsion films.  

PubMed

This paper presents new theoretical and experimental results that quantify the role of surfactant adsorption and the related interfacial tension changes and interfacial forces in the emulsion film drainage and equilibrium. The experimental results were obtained with plane-parallel microscopic films from aqueous sodium dodecyl sulphate solutions formed between two toluene droplets using an improved micro-interferometric technique. The comparison between the theory and the experimental data show that the emulsion film drainage and equilibrium are controlled by the DLVO interfacial forces. The effect of interfacial viscosity and interfacial tension gradient (the Marangoni number) on the film drainage is also significant. PMID:18036602

Karakashev, Stoyan I; Manev, Emil D; Tsekov, Roumen; Nguyen, Anh V

2007-11-12

41

Telomeric THAM-derived perfluoroalkylated surfactants for fluorocarbon emulsions.  

PubMed

New fluorophilic and hydrophilic, cost efficient telomeric surfactants derived from tris(hydroxymethyl)acrylaminomethane were synthesized in 2 steps in 80% yield with respect to the perfluoroalkylated telogen. They demonstrate better ability to emulsify fluorocarbons than Pluronic f-68. The biological tolerance of these new surfactants is remarkable, the perfluorohexyl derivative was tolerated at doses of 4g/kg bw after i.v. injection in mice. None of the perfluoroalkylated THAM derivatives induces hemolysis of human red blood cells at concentrations up to 200g/l in physiological solutions. PMID:1391520

Riess, J G; Pavia, A A; Pucci, B; Zarif, L

1992-01-01

42

Controlled release of retinol from silica particles prepared in O\\/W\\/O emulsion: The effects of surfactants and polymers  

Microsoft Academic Search

Spherical silica particles containing retinol were fabricated by using O\\/W\\/O multiple emulsion and sol–gel method. In this study, when both hydroxypropyl cellulose (HPC) and surfactants such as Tween 20 and Span 80 were used, multiple emulsion encapsulating retinol was prepared successfully. The size of water droplets and the amount of released retinol depended on the concentration of surfactants and PEG

Yi-Jeong Hwang; Chul Oh; Seong-Geun Oh

2005-01-01

43

Comparison of Surfactants Used to Prepare Aqueous Perfluoropentane Emulsions for Pharmaceutical Applications  

PubMed Central

Perfluoropentane (PFP), a highly hydrophobic, non-toxic, non-carcinogenic fluoroalkane, has generated much interest in biomedical applications, including occlusion therapy and controlled drug delivery. For most of these applications, the dispersion within aqueous media of a large quantity of PFP droplets of the proper size is critically important. Surprisingly, the interfacial tension of PFP against water in the presence of surfactants used to stabilize the emulsion has rarely, if ever, been measured. In this study, we report the interfacial tension of PFP in the presence of surfactants used in previous studies to produce emulsions for biomedical applications: polyethylene oxide-co-polylactic acid (PEO-PLA, and polyethylene oxide-co-poly-?-caprolactone (PEO-PCL). Since both of these surfactants are uncharged diblock copolymers that rely on the mechanism of steric stabilization, we also investigate for comparison’s sake use of the small molecule cationic surfactant cetyl trimethyl ammonium bromide (CTAB), and the much larger protein surfactant bovine serum albumin (BSA). The results presented here complement previous reports of the PFP droplet size distribution, and will be useful for determining to what extent the interfacial tension value can be used to control the mean PFP droplet size.

Kandadai, Madhuvanthi A.; Mohan, Praveena; Lin, Genyao; Butterfield, Anthony; Skliar, Mikhail; Magda, Jules J.

2010-01-01

44

Comparison of surfactants used to prepare aqueous perfluoropentane emulsions for pharmaceutical applications.  

PubMed

Perfluoropentane (PFP), a very hydrophobic, nontoxic, noncarcinogenic fluoroalkane, has generated much interest in biomedical applications, including occlusion therapy and controlled drug delivery. For most of these applications, the dispersion within aqueous media of a large quantity of PFP droplets of the proper size is critically important. Surprisingly, the interfacial tension of PFP against water in the presence of surfactants used to stabilize the emulsion has rarely, if ever, been measured. In this study, we report the interfacial tension of PFP in the presence of surfactants used in previous studies to produce emulsions for biomedical applications: polyethylene oxide-co-polylactic acid (PEO-PLA) and polyethylene oxide-co-poly-epsilon-caprolactone (PEO-PCL). Because both of these surfactants are uncharged diblock copolymers that rely on the mechanism of steric stabilization, we also investigate for comparison's sake the use of the small-molecule cationic surfactant cetyl trimethyl ammonium bromide (CTAB) and the much larger protein surfactant bovine serum albumin (BSA). The results presented here complement previous reports of the PFP droplet size distribution and will be useful for determining to what extent the interfacial tension value can be used to control the mean PFP droplet size. PMID:20218695

Kandadai, Madhuvanthi A; Mohan, Praveena; Lin, Genyao; Butterfield, Anthony; Skliar, Mikhail; Magda, Jules J

2010-04-01

45

Synthesis of polystyrene-clay nanocomposites via emulsion polymerization using a reactive surfactant  

Microsoft Academic Search

Summary  \\u000a Polystyrene-clay nanocomposites were synthesized via emulsion polymerization of styrene in the presence of montmorillonite\\u000a particles and a reactive cationic surfactant as the emulsifier. The reactive surfactant, vinylbenzyldodecyldimethylammonium\\u000a chloride (VDAC), was synthesized by the quaternization reaction of vinylbenzyl chloride with dimethyldodecylamine. Partially\\u000a exfoliated nanocomposites were achieved as revealed by X-ray diffraction (XRD) and transmission electron microscopy (TEM).\\u000a Polystyrene-clay nanocomposites prepared

Syed Qutubuddin; Xiao-an Fu; Yousuf Tajuddin

2002-01-01

46

Physical properties and biological activity of poly(butyl acrylate–styrene) nanoparticle emulsions prepared with conventional and polymerizable surfactants  

Microsoft Academic Search

Recent efforts in our laboratory have explored the use of polyacrylate nanoparticles in aqueous media as stable emulsions for potential applications in treating drug-resistant bacterial infections. These emulsions are made by emulsion polymerization of acrylated antibiotic compounds in a mixture of butyl acrylate and styrene (7:3 wt\\/wt) using sodium dodecyl sulfate as a surfactant. Prior work in our group established

Julio C. Garay-Jimenez; Danielle Gergeres; Ashley Young; Daniel V. Lim; Edward Turos

2009-01-01

47

INVESTIGATION OF NON-SETTLING POLYMERIZABLE INVERSE-EMULSIONS AT LOW SURFACTANT AND HIGH MONOMER CONCENTRATION  

Microsoft Academic Search

Polymerized inverse-macroemulsions based on acrylamide and the quaternary ammonium dimethylaminoethyl acrylate were studied and were found to be stable for periods exceeding three months. These low or ‘non’ settling inverse-emulsions were produced by blending small amounts of sorbitan fatty acid esters and polyethoxylated sorbitans with ABA-type block copolymeric surfactants based on similar constituents. Inverse-laticies were produced which had a majority

Huafang Ni; David Hunkeler

1997-01-01

48

Influence of Interfacial Properties of Lipophilic Surfactants on Water-in-Oil Emulsion Stability  

Microsoft Academic Search

The purpose of this study is to investigate interfacial properties of lipophilic nonionic surfactants of the sorbitan fatty acid ester type (Spans 20, 80, 83, and 85) with the aim of selecting appropriate emulsifiers for water-in-oil (W\\/O) emulsions under different conditions. Interfacial tension and rheology were investigated at a planar mineral oil\\/double distilled water interface using a Wilhelmy plate method

Foyeke O. Opawale; Diane J. Burgess

1998-01-01

49

Mixed O/W emulsions stabilized by solid particles: a model system for controlled mass transfer triggered by surfactant addition.  

PubMed

This article deals with a model mixed oil-in-water (O/W) emulsion system developed to study the effect of surfactants on mass transfer between dispersed oil droplets of different composition. In this purpose, our goal was to formulate O/W emulsions without any surface active agents as stabilizer, which was achieved by replacing surfactants by a mixture of hydrophilic/hydrophobic silica particles. Then, to study the specific role of surfactants in the oil transfer process, different types and concentrations of surfactants were added to the mixed emulsion after its preparation. In such a way, the same original emulsion can be used for all experiments and the influence of various surface active molecules on the oil transfer mechanism can be directly studied. The model mixed emulsion used consists of a mixture of hexadecane-in-water and tetradecane-in-water emulsions. The transfer between tetradecane and hexadecane droplets was monitored by using differential scanning calorimetry, which allows the detection of freezing and melting signals characteristic of the composition of the dispersed oil droplets. The results obtained showed that it is possible to trigger the transfer of tetradecane towards hexadecane droplets by adding surfactants at concentrations above their critical micellar concentration, measured in presence of solid particles, through micellar transport mechanism. PMID:22909967

Drelich, Audrey; Grossiord, Jean-Louis; Gomez, François; Clausse, Danièle; Pezron, Isabelle

2012-08-02

50

Effect of surfactants on the porous structure of poly( N -isopropylacrylamide) hydrogels prepared by an emulsion templating method  

Microsoft Academic Search

Stimuli-sensitive porous hydrogels prepared with an emulsion templating method developed by the authors are potentially applicable\\u000a in the medical and pharmaceutical fields; thermosensitive N-isopropylacrylamide (NIPA) hydrogels having randomly distributed sphere-like cavities have been prepared by the polymerization\\u000a in an aqueous phase in an oil-in-water (O\\/W) emulsion, followed by the washing of oil (oleyl alcohol) microdroplets. The surfactant\\u000a plays a dominant

Hideaki Tokuyama; Hiroshi Sumida; Akifumi Kanehara; Susumu Nii

2009-01-01

51

Emulsions and microemulsions of water and carbon dioxide: Novel surfactants and stabilization mechanisms  

NASA Astrophysics Data System (ADS)

During the last two decades colloid and interface science in the field of supercritical fluid technology has brought enormous potentials in the utilization of supercritical carbon dioxide as an environmentally benign solvent. Liquid or supercritical CO2 exhibits solvent properties that are tunable with pressure, and is essentially nontoxic and nonflammable. Emulsions and microemulsions of water and CO2, whether in the form of water-in-CO 2 (w/c) or CO2-in-water (c/w), offer new possibilities for separations on the basis of polarity, and as media for reactions between polar and nonpolar molecules. For the first time, formation of thermodynamically stable c/w microemulsions was characterized by dynamic light scattering (DLS) technique. High-pressure carbon dioxide swells potassium carboxylate perfluoropolyether (PFPE-K) cylindrical micelles in water, elongating the micelles significantly from 20 up to 80 nm. As the micelles swell to form microemulsions, the solubility of pyrene increases by a factor of ca. 10. It was demonstrated w/c microemulsions may be formed with nonionic hydrocarbon surfactant. Methylated branched tail of the surfactant enhances formation of stable w/c microemulsions as it raises surfactant solubility in CO2, shifts the curvature towards bending about water, and weakens interdroplet interactions by reducing overlap between surfactant tails. As a novel medium for reactions, w/c microemulsions with low water content are utilized for the synthesis of TiO2 nanoparticles via the controlled hydrolysis of titanium tetraisopropoxide. The size of particles could be controlled by adjusting the water-to-surfactant ratio (wo). Based on DLS measurements, the size of TiO2 particles was comparable to that of the microemulsion droplets indicating steric stabilization was sufficient during the rapid hydrolysis. Finally, electrostatic repulsion between water droplets of w/c emulsion was explored as an alternative to the steric stabilization mechanism. Negative zeta-potentials as high as 70 mV are measured for emulsion droplets by microelectrophoresis. Unprecedented crystalline structure of the droplet array with a spacing of several droplet-diameters is identified by microscopy, and investigated in terms of a balance between long-range electrostatic repulsions acting through the low dielectric medium (epsilonr = 1.5 for high pressure CO2) and the gravitational force which tends to decrease inter-droplet distances.

Ryoo, Won Sun

52

Treatment of surfactant stabilized oil-in-water emulsions by means of chemical oxidation and coagulation.  

PubMed

The model wastewater samples investigated in the current study represented oil-in-water (O/W) emulsions with small oil (diesel/black oil) and high surfactant (Anrol/Decon90) concentrations generated during washing of oil tankers or tank-wagons. Coagulation with aluminium sulphate, ferric chloride and lime milk, and chemical oxidation by hydrogen peroxide catalyzed ferrous ions were applied as traditional and advanced treatment processes, respectively. Coagulation proved more feasible for oil content removal than for COD reduction. Both COD and oil content removal, were higher if Anrol was used as a surface active agent. The comparison of wastewater samples with different oil products but the same detergent showed more effective black oil removal. Coagulation was found ineffective as a pre-treatment technology for biodegradability improvement and toxicity reduction in surfactant stabilized O/W emulsion wastewater samples. The application of Fenton chemistry showed significant COD, UV absorbance and BOD removal, but no improvement in wastewater samples biodegradability. The maximum COD reduction and oil content removal from wastewater samples was above 90%. The oxidation of wastewater containing Decon90 required higher dosages of the Fenton reagent than wastewater with Anrol. Both Anrol and Decon90 contaminated wastewater samples were found to be detoxified even after moderate hydrogen peroxide dosages had been applied in the oxidation step. PMID:18341145

Kulik, N; Trapido, M; Veressinina, Y; Munter, R

2007-12-01

53

Substitution of Non-Biodegradable Surfactants Used in Emulsion Polymerizations - A Study of the Polymerization Process and Performance of Products Obtained  

Microsoft Academic Search

Emulsion polymerization is considered a safe, economic, versatile, and consequently of interest as an environmentally friendly process. However , surfactants utilized need to be biodegradable , and still guarantee a good film quality , with an adequate performance according to its end use. We investigated the substitution of an alkyl phenol ethoxylated (APE) surfactant ,commonly for a sulfosuccinate surfactant ,

C. R. S. Buono; E. Bittencourt

54

The substitution of non biodegradable surfactants used in emulsion polymerizations - A study of the polymerization process and performance of products obtained for paint formulations  

Microsoft Academic Search

Emulsion polymerization is considered a safe, economic, versatile, and consequently of interest as an environmentally friendly process. However , surfactants utilized need to be biodegradable , and still guarantee a good film quality , with an adequate performance according to its end use. We investigated the substitution of an alkyl phenol ethoxylated (APE) surfactant ,commonly for a sulfosuccinate surfactant ,

Celia R. S. Buono; Edison Bittencourt

55

Phase and Topological Behavior of Lyotropic Chromonic Liquid Crystals in Double Emulsions  

NASA Astrophysics Data System (ADS)

Lyotropic chromonic liquid crystals, assembled by non-covalent interactions, have fascinating temperature- and concentration-dependent phase behavior. Using water-oil-water double emulsions, we are able control the inner droplet chromonic phase concentration by osmosis through the oil phase. We then study the configurations of the chromonic liquid crystal phases in droplets by varying the oil types, oil soluble surfactants, and inner droplet diameter. We employ polarization microscopy to observe resulting nematic and columnar phases of Sunset Yellow FCF, and we deduce the liquid crystal configuration of both phases within the droplets. Simulations based on Jones matrices confirm droplet appearance, and preliminary observations of chromonic liquid crystal shells in oil-water-oil double emulsions are reported.

Davidson, Zoey S.; Jeong, Joonwoo; Tu, Fuquan; Lohr, Matt; Lee, Daeyeon; Collings, Peter J.; Lubensky, Tom C.; Yodh, A. G.

2013-03-01

56

Effect of surfactants on interfacial films and stability of water-in-oil emulsions stabilized by asphaltenes.  

PubMed

The effect of additives on asphaltene interfacial films and emulsion stability was analyzed through the change in film properties. Surface pressure isotherms were measured at 23°C for model interfaces between aqueous surfactant solutions and asphaltenes dissolved in toluene and heptane-toluene mixtures. Compressibility, crumpling film ratio and surface pressure were determined from the surface pressure isotherms. The stability of water-in-oil emulsions was determined for the same systems based on the proportion of unresolved emulsified water after repeated treatment involving heating at 60°C and centrifugation. Experimental variables included concentration of asphaltenes (5 and 10 kg/m(3)), concentration and type of surfactant (Aerosol OT, nonylphenol ethoxylates, polypropylene oxide block-copolymer, dodecylbenzene sulfonic acids, dodecylbenzene sulfonic acid-polymer blend, diisopropyl naphthalene sulfonic acid, and sodium naphthenate) and aging time (from 10 min to 4 h). Additives were found to have two opposing effects on film properties and emulsion stability: (1) decreasing or eliminating the crumpling ratio which destabilized emulsions and (2) decreasing interfacial tension which enhanced emulsion stability. A stability parameter was defined to include both the crumpling ratio and interfacial tension and provided a consistent correlation for the percent residual emulsified water. PMID:20804982

Ortiz, D P; Baydak, E N; Yarranton, H W

2010-08-13

57

An Algorithm for Emulsion Stability Simulations: Account of Flocculation, Coalescence, Surfactant Adsorption and the Process of Ostwald Ripening  

PubMed Central

The first algorithm for Emulsion Stability Simulations (ESS) was presented at the V Conferencia Iberoamericana sobre Equilibrio de Fases y Diseño de Procesos [Luis, J.; García-Sucre, M.; Urbina-Villalba, G. Brownian Dynamics Simulation of Emulsion Stability In: Equifase 99. Libro de Actas, 1st Ed., Tojo J., Arce, A., Eds.; Solucion’s: Vigo, Spain, 1999; Volume 2, pp. 364–369]. The former version of the program consisted on a minor modification of the Brownian Dynamics algorithm to account for the coalescence of drops. The present version of the program contains elaborate routines for time-dependent surfactant adsorption, average diffusion constants, and Ostwald ripening.

Urbina-Villalba, German

2009-01-01

58

Proteins, polysaccharides, and their complexes used as stabilizers for emulsions: alternatives to synthetic surfactants in the pharmaceutical field?  

PubMed

Emulsions are widely used in pharmaceutics for the encapsulation, solubilization, entrapment, and controlled delivery of active ingredients. In order to answer the increasing demand for clean label excipients, natural polymers can replace the potentially irritative synthetic surfactants used in emulsion formulation. Indeed, biopolymers are currently used in the food industry to stabilize emulsions, and they appear as promising candidates in the pharmaceutical field too. All proteins and some polysaccharides are able to adsorb at a globule surface, thus decreasing the interfacial tension and enhancing the interfacial elasticity. However, most polysaccharides stabilize emulsions simply by increasing the viscosity of the continuous phase. Proteins and polysaccharides may also be associated either through covalent bonding or electrostatic interactions. The combination of the properties of these biopolymers under appropriate conditions leads to increased emulsion stability. Alternative layers of oppositely charged biopolymers can also be formed around the globules to obtain multi-layered "membranes". These layers can provide electrostatic and steric stabilization thus improving thermal stability and resistance to external treatment. The novel biopolymer-stabilized emulsions have a great potential in the pharmaceutical field for encapsulation, controlled digestion, and targeted release although several challenging issues such as storage and bacteriological concerns still need to be addressed. PMID:22759644

Bouyer, Eléonore; Mekhloufi, Ghozlene; Rosilio, Véronique; Grossiord, Jean-Louis; Agnely, Florence

2012-07-01

59

Stability and rheology of emulsions containing sodium caseinate: combined effects of ionic calcium and non-ionic surfactant  

Microsoft Academic Search

We have investigated the effect of the combination of ionic calcium and non-ionic surfactant (Tween 20) on the visual creaming behaviour and rheology of n-tetradecane-in-water emulsions (4wt% protein, 30vol% oil, mean droplet diameter 0.4?m) prepared at pH 6.8 with sodium caseinate. Varying concentrations of ionic calcium, expressed as the calcium\\/caseinate molar ratio R, were incorporated before homogenization, and varying concentrations

Eric Dickinson; Stewart J. Radford; Matt Golding

2003-01-01

60

Size controlled synthesis of sub-100 nm monodisperse poly(methylmethacrylate) nanoparticles using surfactant-free emulsion polymerization  

Microsoft Academic Search

Surfactant-free emulsion polymerization (SFEP) is a well-known technique for the production of polymeric nanoparticles that does not require post-synthetic cleaning steps. Obtaining hydrophobic particles at sub-100nm scale, however, is quite challenging with this polymerization method. Here, we demonstrate a single step synthetic approach that yields poly(methylmethacrylate) (PMMA) nanoparticles with controlled sub-100nm size and relatively high resultant solid content. Dynamic light

Sevket Tolga Camli; Fatih Buyukserin; Oguz Balci; Gurer Guven Budak

2010-01-01

61

Effect of added salts in water on the hydrophile-lipophile balance of nonionic surfactants: the effect of added salts on the phase inversion temperature of emulsions  

Microsoft Academic Search

Although an HLB-value is assigned to a definite surfactant, the real hydrophile-lipophile balance (HLB) of surfactant at the oil-water interface changes with the amount and kinds of added salts in water as well as with the types of oils. On the other hand, the phase inversion temperature (PIT) of emulsions accurately reflects that the real HLB of surfactants in a

K. Shinoda; H. Takeda

1970-01-01

62

Percolation behavior in W/O emulsions stabilized by interfacially active fractions from crude oils in high external electric fields  

SciTech Connect

In this communication the authors report on a percolation behavior of water in oil emulsions stabilized by indigenous surfactants from crude oils in high external electric fields. The static permittivity of the emulsion investigated increases with the applied electric field. When the electric field reaches a certain strength the system collapses and the permittivity of the system resembles that of a series coupling of the water and the oil domains. Regression analysis of a proposed scaling law shows that the system behaves according to a static percolation model, i.e., a bicontinuous system. The authors compare the percolation behavior in high electric fields to that reported in temperature and conductivity studies in w/o microemulsions.

Foerdedal, H.; Sjoeblom, J. [Univ. of Bergen (Norway). Dept. of Chemistry

1996-08-10

63

Synthesis of glucose-responsive bioconjugated gel particles using surfactant-free emulsion polymerization.  

PubMed

Bioconjugated gel particles that have complexes composed of lectin concanavalin A (ConA) and 2-glucosyloxyethyl methacrylate (GEMA) were synthesized by the surfactant-free emulsion copolymerization of N,N-diethylaminoethyl methacrylate (DEAEMA), poly(ethylene glycol) dimethacrylate (PEGDMA), GEMA, and modified-ConA with polymerizable groups. The resultant gel particles having GEMA-ConA complexes (GEMA-ConA gel particles) were colloidally stable in a phosphate buffer solution and had a diameter of approximately 750nm. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements implied that GEMA-ConA gel particles have core-shell structures consisting of a hydrophobic core of DEAEMA and a hydrophilic shell of GEMA and PEGDMA containing ConA. GEMA-ConA gel particles underwent a change in size in response to glucose in a phosphate buffer solution. The swelling ratio of GEMA-ConA gel particles gradually increased with an increase in the glucose concentration. On the other hand, the swelling ratio of GEMA-ConA gel particles remained unchanged in a phosphate buffer solution containing galactose. The glucose-responsive swelling of GEMA-ConA gel particles was induced by the dissociation of GEMA-ConA complexes acting as reversible cross-links, because free glucose behaved as an inhibitor of GEMA-ConA complexes. These results indicate that GEMA-ConA gel particles can recognize glucose selectively and undergo changes in size in response to the glucose concentration. The smart functions of glucose-responsive gel particles can provide tools for constructing self-regulated drug delivery systems and sensor systems useful for treating diabetes. PMID:22078928

Kawamura, Akifumi; Hata, Yuta; Miyata, Takashi; Uragami, Tadashi

2011-10-21

64

Pickering emulsions stabilized by a lipophilic surfactant and hydrophilic platelike particles.  

PubMed

Liquid paraffin-water emulsions were prepared by homogenizing oil phases containing sorbitan oleate (Span 80) and aqueous phases containing layered double hydroxide (LDH) particles or Laponite particles. While water-in-oil (w/o) emulsions are obtained by combining LDH with Span 80, the emulsions stabilized by Laponite-Span 80 are always o/w types regardless of the Span 80 concentration. Laser-induced fluorescent confocal micrographs indicate that particles are absorbed on the emulsion surfaces, suggesting all the emulsions are stabilized by the particles. The difference of the particle-stabilized emulsion type may be explained by comparing particle contact angles and the oil-water interfacial tensions, indicating that more Span 80 molecules are adsorbed on the LDH particles than on Laponite. Apparently, the LDH particles are rendered more hydrophobic by Span 80, resulting in the formation of w/o emulsions. The long-term stability of the emulsions was also compared. Emulsions stabilized by Span 80 alone completely separate into two bulk phases of oil and water after 3 months. However, emulsion stability is greatly enhanced with the addition of LDH or Laponite particles. This synergism was accounted for by an increase of the dilational viscoelasticity modulus of the oil-water interface after particles were added to the aqueous phase. This increase indicates that the gel-like particle layer stays at the oil-water interface and resists emulsion coalescence. Scanning electron microscope (SEM) images display the presence of a firm layer surrounding the emulsion droplets and a three-dimensional particle network which extends into the bulk phase aiding emulsion stability. PMID:20020723

Wang, Jun; Yang, Fei; Tan, Junjun; Liu, Guopeng; Xu, Jian; Sun, Dejun

2010-04-20

65

Phase Behavior of Oil\\/Water\\/Nonionic Surfactant Systems  

Microsoft Academic Search

The phase behavior of oil\\/water\\/nonionic surfactant systems under the effect of temperature is usually only measured at an oil?to?water ratio of 1:1 (? = 0.5). It was found that with increasing oil?chain length and increasing hydrophilicity of the surfactant (Triton X?114 to Triton X?100), the three?phase region widens toward higher temperatures. The clear inclination of the “fishes” at constant oil?to?water ratios shows

Yuksel Bayrak; Mehmet Iscan

2005-01-01

66

Effect of nonionic surfactant on transport of surface-active and non-surface-active model drugs and emulsion stability in triphasic systems  

Microsoft Academic Search

The effect of surfactant concentration on transport kinetics in emulsions using surface-active (phenobarbital, barbital) and\\u000a non- surface-active is determined. Mineral oil was chosen as the oil phase and the nonionic surfactant polyoxyethylene-10-oleyl-ether\\u000a (Brij 97) was chosen as the emulsifier. Model drug transport in the triphasic systems was investigated using side-by-side\\u000a diffusion cells mounted with hydrophilic dialysis membranes (molecular weight cutoffs

N. Chidambaram; D. J. Burgess

2000-01-01

67

Observations on the coalescence behavior of oil droplets and emulsion stability in enhanced oil recovery  

Microsoft Academic Search

Results of experiments on the stability of crude oil drops at an oil-water interface and interdroplet coalescence in crude oil-water emulsions containing petroleum sulfonates as surfactant systems, cosurfactants, and other chemical additives have been analyzed in terms of interfacial viscosity, interfacial tension, interfacial charge, and thickness of the films surrounding the microdroplets. A qualitative correlation has been found between coalesence

D. T. Wasan; S. M. Shah; N. Aderangi; M. Chan; J. J. McNamara

1977-01-01

68

Evaluation of a novel soybean oil-based surfactant for fine emulsion preparation  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soybean oil is currently the world’s second largest source of vegetable oil. The growth in soybean oil production and the concerns over petrochemical surfactants have promoted the development of soybean oil-based surfactants. In this paper, we briefly describe the synthesis and properties of soybean...

69

Oscillatory, creep and steady flow behavior of xanthan-thickened oil-in-water emulsions  

Microsoft Academic Search

In the handling, mixing, storage, and pipeline transportation of emulsions, knowledge of rheological properties is required for the design, selection, and operation of the equipment involved. The rheological behavior of xanthan gum-thickened oil-in-water emulsions is studied with a cone-and-plate system using a constant-stress rheometer. Xanthan gum solutions and xanthan-thickened oil-in-water emulsions are strongly shear-thinning and viscoelastic in nature. The effects

Rajinder Pal

1995-01-01

70

Engineering interfacial properties by anionic surfactant-chitosan complexes to improve stability of oil-in-water emulsions.  

PubMed

Oil-in-water emulsions (10% w/w n-tetradecane) were prepared at pH = 5.7 by using, as surface active agents, electrostatically formed complexes of sodium stearoyl lactylate (SSL) at a concentration of 0.4% (w/w) and chitosan (CH) in a concentration range between 0 and 0.48% w/w. The use of complexes in emulsions with a low concentration of CH (<0.24% w/w) resulted in highly flocculated systems; instead, with increased level of CH, the emulsions had a smaller average droplet size and exhibited greater stability during storage. Emulsions stabilised by SSL/CH complexes showed non-Newtonian flow behavior with pronounced shear thinning. Among all formulations studied none showed a gel-like behavior since in all cases the G' (storage modulus) was lower that G'' (loss modulus). Adsorption kinetics of pure SSL and SSL/CH complexes to the oil/water interfaces were evaluated using an automated drop tensiometer (ADT). Even though complexation of SSL with CH resulted in a delay of the adsorption of the surface active species at the oil/water interface, the inclusion of the polysaccharide resulted in substantially improved interfacial properties as indicated by a significant increase of the dilatational modulus. Furthermore, the enhanced interfacial properties of the emulsion droplets resulted in improved stability against freeze-thaw cycling. The results of this study may facilitate the development of frozen food products such as desserts with an ameliorated stability and favorable sensorial characteristics. PMID:22298029

Zinoviadou, Kyriaki G; Scholten, Elke; Moschakis, Thomas; Biliaderis, Costas G

2012-02-02

71

Emulsion Liquid Membrane for the Recovery Chromium (VI) from Effluents Using Monosuccimide and Bisuccimide as Surfactant  

Microsoft Academic Search

An emulsion liquid membrane (ELM) process is being developed for application to many industrial waste treatment problems. Using the ELM technique to remove chromium (VI) from electroplating effluent with the objective of reducing levels to below allowable discharge limits was investigated. In this work, tertiary amine N7301 was chosen as a carrier. In establishing a mental recovery process using ELM,

Hongxia Li; Xiwen He; Yinghua Liang

2003-01-01

72

Stability Behavior of Water-in-Diesel Fuel Emulsion  

Microsoft Academic Search

The presence of water within diesel fuel in the form of water-in-diesel (W\\/D) emulsion lowers the pollution level of nitrogen oxides and particulate matter. Emulsion of W\\/D was prepared by high-speed mixing and gradually adding water into the diesel fuel containing a small amount of emulsified agent. We measured the physical properties of diesel fuel and W\\/D emulsions with a

M. T. Ghannam; M. Y. E. Selim

2009-01-01

73

Solubilization rates of oils in surfactant solutions and their relationship to mass transport in emulsions  

Microsoft Academic Search

Information on solubilization rates of oils in aqueous micellar solutions is reviewed. For ionic surfactants electrostatic repulsion prevents close approach of micelles to the oil–water interface, so that solubilization results from oil molecules dissolving individually in the solution and being taken up by micelles during and\\/or after transport across a diffusion boundary layer to the bulk solution. Experiments with SDS

Alejandro A. Peña; Clarence A. Miller

2006-01-01

74

Modeling Thermodynamic Behavior of Nonionic Surfactants in Water  

NASA Astrophysics Data System (ADS)

Aqueous solutions of nonionic surfactants exhibit a non-trivial phase behavior known as lower critical solution temperature (UCST), where solutions are homogeneous at lower temperatures but become cloudy (two-phase) at higher temperatures. Conventional Flory-HugginsootnotetextM. L. Huggins, J. Chem. Phys. 9, 440 (1941); P. J. Flory, J. Chem. Phys. 9, 660 (1941). theory of polymer solutions fails to describe such phase behavior. We utilize the approach suggested by DormidontovaootnotetextE. E. Dormidontova, Macromolecules 35, 987 (2002). and modify Flory-Huggins theory by explicitly accounting for water-water and water-alkylene oxide hydrogen bonding. While the Dormidontova model was restricted to aqueous solutions of polyethylene oxide (PEO), we extend it to include other monomers and their copolymers. With the new approach, we can semi-quantitatively predict cloud points of various nonionic surfactants (Tergitol L and Ecosurf series) as functions of their molecular structures. We also discuss extensions of this model to calculate micellar phase behavior and oil/water/surfactant interfacial tensions. Trademark of The Dow Chemical Company

Ginzburg, Valeriy; Varineau, Pierre

2009-03-01

75

The Hydrophile-Lipophile Balance of Mixed Nonionic Surfactants  

Microsoft Academic Search

Synopsis The partition behavior of homogeneous and Poisson distribution nonionic surfactants in the oil-water system was studied in connection with the type of emulsion produced. The partition isotherms exhibited an abrupt change of slope at the critical micelle concentration. It was shown that the phase in which micelles are formed will be the continuous phase in the formation of emulsions.

FUMINORI HARUSAWA; HIDEO NAKAJIMA

76

Oscillatory, creep and steady flow behavior of xanthan-thickened oil-in-water emulsions  

SciTech Connect

In the handling, mixing, storage, and pipeline transportation of emulsions, knowledge of rheological properties is required for the design, selection, and operation of the equipment involved. The rheological behavior of xanthan gum-thickened oil-in-water emulsions is studied with a cone-and-plate system using a constant-stress rheometer. Xanthan gum solutions and xanthan-thickened oil-in-water emulsions are strongly shear-thinning and viscoelastic in nature. The effects of polymer and oil concentrations on the rheological behavior of emulsions are investigated. The relative viscosity for the thickened emulsions, at any given oil concentration, increases with an increase in the shear rate, whereas the unthickened emulsions show the opposite trend. The theoretical models give reasonable predictions for the relative viscosity, storage modulus, and loss modulus of xanthan-thickened emulsions. The ratio of storage to loss moduli increases considerably with the increase in polymer and oil concentrations. The creep/recovery experiments confirm that the xanthan-thickened emulsions are highly viscoelastic in nature and that the degree of elasticity increases with the increase in polymer and oil concentrations.

Pal, R. [Univ. of Waterloo, Ontario (Canada). Dept. of Chemical Engineering

1995-04-01

77

Renormalized Ising behavior of critical nonionic surfactant solution  

NASA Astrophysics Data System (ADS)

The critical behavior of a nonionic surfactant, heptaethyleneglycol mono-n-tetradecyl ether (C14E7), in an aqueous tetramethylammonium chloride (TMAC) solution was investigated by the combined use of turbidity and light scattering measurements concerning the critical exponents of the isothermal osmotic compressibility and the long-range correlation length. Both the critical exponents and the critical points depend on the TMAC concentration. Critical exponents increase with the increase of salt concentration showing a deviation from the three-dimensional Ising model. The critical behaviors are well described by a continuous change from the three-dimensional Ising model to Fisher's renormalized Ising model.

Kubota, Kenji; Kita, Rio; Dobashi, Toshiaki

1998-07-01

78

Formation of water-in-oil (W\\/O) nano-emulsions in a water\\/mixed non-ionic surfactant\\/oil systems prepared by a low-energy emulsification method  

Microsoft Academic Search

W\\/O nano-emulsion formation by a low-energy emulsification method is described for the first time. The nano-emulsions have been formed in water\\/mixed Cremophor EL:Cremophor WO7 surfactant\\/isopropyl myristate systems at Cremophor EL:Cremophor WO7 ratios between 1:2 and 1:9, by slow addition of isopropyl myristate to surfactant\\/water mixtures. Phase behaviour studies have showed that the compositions giving rise to W\\/O nano-emulsions belong to

N. Usón; M. J. Garcia; C. Solans

2004-01-01

79

Soil particle-size dependent partitioning behavior of pesticides within water–soil–cationic surfactant systems  

Microsoft Academic Search

Cationic surfactants have been proposed for enhanced sorption zones to contain hydrophobic organic compound (HOC) contamination. Benzalkonium chloride (BC), a cationic surfactant, was selected to study the particle-size dependent sorption behavior of the surfactant and its role in the immobilization of two hydrophobic pesticides (atrazine and diuron) within soil–water–surfactant systems for this application. Five different soils were considered in this

Peng Wang; Arturo A. Keller

2008-01-01

80

Synthesis and aggregation behavior of a hexameric quaternary ammonium surfactant.  

PubMed

A star-shaped hexameric quaternary ammonium surfactant (PAHB), bearing six hydrophobic chains and six charged hydrophilic headgroups connected by an amide-type spacer group, was synthesized. The self-assembly behavior of the surfactant in aqueous solution was studied by surface tension, electrical conductivity, isothermal titration microcalorimetry, dynamic light scattering, cryogenic transmission electron microscopy, and NMR techniques. The results reveal that there are two critical aggregate concentrations during the process of aggregation, namely C(1) and C(2). The aggregate transitions are proved to be caused by the changes of the surfactant configuration through hydrophobic interaction among the hydrocarbon chains. Below C(1), PAHB may present a star-shaped molecular configuration due to intramolecular electrostatic repulsion among the charged headgroups, and large aggregates with network-like structure are observed. Between C(1) and C(2), the hydrophobic interaction among the hydrophobic chains may become stronger to make the hydrophobic chains of the PAHB molecules curve back and pack more closely, and then the network-like aggregates transfer to large spherical aggregates of ?100 nm. Beyond C(2), the hydrophobic interaction may become strong enough to cause the PAHB molecular configuration to turn into a pyramid-like shape, resulting in the transition of the spherical large aggregates to spherical micelles of ?10 nm. Interestingly, the PAHB displays high emulsification ability to linear fatty alkyls even at very low concentration. PMID:21797217

Fan, Yaxun; Hou, Yanbo; Xiang, Junfeng; Yu, Defeng; Wu, Chunxian; Tian, Maozhang; Han, Yuchun; Wang, Yilin

2011-08-09

81

Phase behavior and oil recovery investigations using mixed and alkaline-enhanced surfactant systems  

SciTech Connect

The results of an evaluation of different mixed surfactant and alkaline-enhanced surfactant systems for enhanced oil recovery are described. Several mixed surfactant systems have been studies to evaluate their oil recovery potential as well as improved adaptability to different ranges of salinity, divalent ion concentrations, and temperature. Several combinations of screening methods were used to help identify potential chemical formulations and determine conditions where particular chemical systems can be applied. The effects of different parameters on the behavior of the overall surfactant system were also studied. Several commercially available surfactants were tested as primary components in the mixtures used in the study. These surfactants were formulated with different secondary as well as tertiary components, including ethoxylated and non-ethoxylated sulfonates and sulfates. Improved salinity and hardness tolerance was achieved for some of these chemical systems. The salinity tolerance of these systems were found to be dependent on the molecular weight, surfactant type, and concentration of the surfactant components.

Llave, F.M.; Gall, B.L.; French, T.R.; Noll, L.A.; Munden, S.A.

1992-03-01

82

Study of the cloud point behavior of high oleate ester-derived nonionic surfactant  

NASA Astrophysics Data System (ADS)

The cloud point behavior of high oleate ester-derived nonionic surfactant has been studied. The effect of various polyethoxylate chain lengths (polyethylene glycol with ethylene oxide monomer 7, 11 and 16 units) as the surfactant's hydrophilic head and the effect of sodium chloride and ionic surfactants on the cloud points of nonionic surfactants synthesized were investigated. When the chain length of polyethoxylate increased, the cloud point of the synthesized nonionic surfactant also increased. Sodium chloride was found to depress the cloud point values of the formed nonionic surfactants with a linear decrease in relation to the concentration of sodium chloride used. Ionic surfactants lifted the cloud points of synthesized nonionic surfactant but in the presence of sodium chloride, the cloud point of mixed ionic-nonionic solution was suppressed.

Tan, Isa M.; Lee, Susan Y. C.; Mushtaq, M.

2012-09-01

83

Creaming behavior of solids-stabilized oil-in-water emulsions  

SciTech Connect

Sedimentation of a suspension of particles under the action of gravity has been studied extensively due to its importance in practical applications such as oil sands extraction, solid-liquid separation, particle size measurement, dewatering of coal slurries, clarification of waste water, and processing of drilling and mining fluids containing rocks and mineral particles of various sizes. Creaming behavior of oil-in-water emulsions stabilized by kaolinite clays was studied here. The clays were treated with asphaltenes resulting in clays having different contact angles. It was found that the emulsion creaming velocity decreased and that the volume of the creamed emulsions increased with increasing clay concentration at the oil droplet surface. At a given initial clay concentration in the aqueous phase, a plot of the emulsion creaming velocity versus the square of the oil droplet diameter did not follow any rational hindered settling equation. At a constant clay concentration at the oil droplet surface, however, a plot of the emulsion creaming velocity versus the square of the effective oil droplet diameter gave a straight line passing through the origin. A model for creaming of solids-stabilized oil-in-water emulsions was developed, and it is able to predict the creaming velocity of the emulsions quite well.

Yan, N.; Masliyah, J.H. [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical Engineering

1997-04-01

84

Effect of surfactant and surfactant blends on pseudoternary phase diagram behavior of newly synthesized palm kernel oil esters  

PubMed Central

Background: The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters. Methods: Nonionic surfactant blends of Tween® and Tween®/Span® series were screened based on their solubilization capacity with water for palm kernel oil esters. Tween® 80 and five blends of Tween® 80/Span® 80 and Tween® 80/Span® 85 in the hydrophilic-lipophilic balance (HLB) value range of 10.7–14.0 were selected to study the phase diagram behavior of palm kernel oil esters using the water titration method at room temperature. Results: High solubilization capacity was obtained by Tween® 80 compared with other surfactants of Tween® series. High HLB blends of Tween® 80/Span® 85 and Tween® 80/Span® 80 at HLB 13.7 and 13.9, respectively, have better solubilization capacity compared with the lower HLB values of Tween® 80/Span® 80. All the selected blends of surfactants were formed as water-in-oil microemulsions, and other dispersion systems varied in size and geometrical layout in the triangles. The high solubilization capacity and larger areas of the water-in-oil microemulsion systems were due to the structural similarity between the lipophilic tail of Tween® 80 and the oleyl group of the palm kernel oil esters. Conclusion: This study suggests that the phase diagram behavior of palm kernel oil esters, water, and nonionic surfactants is not only affected by the HLB value, but also by the structural similarity between palm kernel oil esters and the surfactant used. The information gathered in this study is useful for researchers and manufacturers interested in using palm kernel oil esters in pharmaceutical and cosmetic preparation. The use of palm kernel oil esters can improve drug delivery and reduce the cost of cosmetics.

Mahdi, Elrashid Saleh; Sakeena, Mohamed HF; Abdulkarim, Muthanna F; Abdullah, Ghassan Z; Sattar, Munavvar Abdul; Noor, Azmin Mohd

2011-01-01

85

Optical properties of core\\/shell typed PMMA\\/CdS nanoparticles prepared by in situ and ex situ surfactant-free emulsion polymerization  

Microsoft Academic Search

Core\\/shell poly(methyl methacrylate)\\/cadmium sulfide (PMMA\\/CdS) nanoparticles were prepared by surfactant-free emulsion copolymerization\\u000a with 2-(dimethylamino)ethyl methacrylate (DMAEMA) auxiliary monomer. According to the addition time of Cd2+ ions, the synthesis of the hybrid nanoparticles was conducted in in situ and ex situ techniques. The core\\/shell PMMA\\/CdS\\u000a nanoparticles synthesized by the post-addition (ex situ) of Cd2+ ions showed a wide size distribution and

Hyojung Yoon; Young-Mok Rhym; Sang Eun Shim

2011-01-01

86

Screening of mixed surfactant systems: Phase behavior studies and CT imaging of surfactant-enhanced oil recovery experiments  

SciTech Connect

A systematic chemical screening study was conducted on selected anionic-nonionic and nonionic-nonionic systems. The objective of the study was to evaluate and determine combinations of these surfactants that would exhibit favorable phase behavior and solubilization capacity. The effects of different parameters including (a) salinity, (b) temperature, (c) alkane carbon number, (c) hydrophilic/lipophilic balance (HLB) of nonionic component, and (d) type of surfactant on the behavior of the overall chemical system were evaluated. The current work was conducted using a series of ethoxylated nonionic surfactants in combinations of several anionic systems with various hydrocarbons. Efforts to correlate the behavior of these mixed systems led to the development of several models for the chemical systems tested. The models were used to compare the different systems and provided some guidelines for formulating them to account for variations in salinity, oil hydrocarbon number, and temperature. The models were also evaluated to determine conformance with the results from experimental measurements. The models provided good agreement with experimental results. X-ray computed tomography (CT) was used to study fluid distributions during chemical enhanced oil recovery experiments. CT-monitored corefloods were conducted to examine the effect of changing surfactant slug size injection on oil bank formation and propagation. Reducing surfactant slug size resulted in lower total oil production. Oil recovery results, however, did not correlate with slug size for the low-concentration, alkaline, mixed surfactant system used in these tests. The CT measurements showed that polymer mobility control and core features also affected the overall oil recovery results.

Llave, F.M.; Gall, B.L.; Lorenz, P.B.; Cook, I.M.; Scott, L.J.

1993-11-01

87

Linear viscoelasticity of emulsions : II. Measurements of the linear viscoelastic behavior of emulsions in the kilohertz range  

Microsoft Academic Search

Linear viscoelasticity of emulsions in shear deformation in the kilohertz range is demonstrated experimentally. In order to avoid complications due to inertia effects, emulsions with small droplet sizes are studied. The preliminary measurements are interpreted as being the result of droplet deformations. If this interpretation is correct, measurements of the dynamic viscosity of emulsions may be used to obtain information

M. Oosterbroek; J. Mellema; J. S. Lopulissa

1981-01-01

88

Synergistic Behavior Between Zwitterionic Surfactant ?-Decylbetaine and Anionic Surfactant Sodium Dodecyl Sulfate  

Microsoft Academic Search

Here, we present experimental surface tension isotherms of mixed solutions of a zwitterionic surfactant ?-decylbetaine (DB)\\u000a and an anionic surfactant sodium dodecyl sulfate (SDS) in different molar ratios. These mixed solutions show a composition\\u000a dependency with respect to both surface tension effectiveness and critical micelle concentration. The pseudo-regular solution\\u000a theory has been used to evaluate the interaction parameters in the

Ze-yun Wang; Shu-fen Zhang; Yun Fang; Li-yun Qi

2010-01-01

89

Effects of foliar surfactants on host plant selection behavior of Liriomyza huidobrensis (Diptera: Agromyzidae).  

PubMed

The pea leafminer, Liriomyza huidobrensis (Diptera: Agromyzidae), is a highly polyphagous insect pest of global distribution. L. huidobrensis feeds and lays its eggs on leaf tissue and reduces crop marketability because of stippling and mining damage. In field insecticide trials, it was observed that stippling was reduced on plants treated with surfactant alone. The objectives of this study were to determine the effect of surfactants on host selection behaviors of female L. huidobrensis and to assess the phytotoxicity of two common surfactants to test plants. The application of the surfactant Sylgard 309 to celery (Apium graveolens) caused a significant reduction in stippling rates. The application of Agral 90 to cucumber leaves (Cucumis sativus) resulted in changes to the amount of effort invested by females in specific host plant selection behaviors, as well as causing a significant reduction in the amount of stippling damage. The recommended dose of Sylgard 309 does not induce phytotoxicity on celery over a range of age classes nor does Agral 90 cause a phytotoxic effect in 35-d-old cucumber. Thus, reductions in observed stippling and changes to host selection behaviors were caused by an antixenotic effect of the surfactant on L. huidobrensis rather than a toxic effect of the surfactant on the plant. The presence of surfactant on an otherwise acceptable host plant seems to have masked host plant cues and prevented host plant recognition. Results indicate that surfactants may be used to reduce leafminer damage to vegetable crops, potentially reducing the use of insecticides. PMID:19825293

McKee, Fraser R; Levac, Joshua; Hallett, Rebecca H

2009-10-01

90

Morphology, thermal behavior, and stability of self-assembled supramolecular tubules from lysine-based surfactants.  

PubMed

Synthetic amino acid-based surfactants possess versatile aggregation properties and are typically more biocompatible and biodegradable than surfactants with conventional headgroups. This opens the possibility of a myriad of specialty applications, namely in pharmaceutics, cosmetics, biomedicine, and nanotemplating chemistry. In this work, we have investigated the interfacial and self-assembling properties in aqueous medium of novel double-chained lysine-based surfactants, with particular focus on the behavior of the dodecyl derivative, 12Lys12. Upon cooling from dilute isotropic micellar solutions, this surfactant crystallizes into micrometer-sized tubular structures that induce gelation of the system. The tubules have been characterized in terms of morphology, assembly process, thermal behavior, and stability, by using differential scanning calorimetry, light and scanning electron microscopy, and deuterium NMR. Possible mechanisms for tubule assembly are discussed, on the basis of surfactant molecular shape, H-bonding and electrostatic interactions, and chirality effects. PMID:23906181

Brito, Rodrigo O; Oliveira, Isabel S; Araújo, Maria J; Marques, Eduardo F

2013-08-01

91

PHASE BEHAVIOR OF WATER/PERCHLOROETHYLENE/ANIONIC SURFACTANT SYSTEMS  

EPA Science Inventory

Winsor Type I (o/w), Type II (w/o), and Type III (middle phase) microemulsions have been generated for water and perchloroethylene (PCE) in combination with anionic surfactants and the appropriate electrolyte concentration. The surfactant formulation was a combination of sodium d...

92

Linear viscoelasticity of emulsions. Part 2. Measurements of the linear viscoelastic behavior of emulsions in the kilohertz range  

SciTech Connect

Linear viscoelasticity of emulsions in shear deformation in the kilohertz range is demonstrated experimentally. In order to avoid complications due to inertia effects, emulsions with small droplet sizes are studied. The preliminary measurements are interpreted as being the result of droplet deformations. If this interpretation is correct, measurements of the dynamic viscosity of emulsions may be used to obtain information about the mechanical properties of the interfacial layer between droplets and the continuous phase. In particular, the evaluation of the interfacial tension of emulsion droplets from bulk properties might be possible using this technique. 21 references.

Oosterbroek, M.; Mellema, J.; Lopulissa, J.S.

1981-11-01

93

Mixed Micellization Behavior of Gemini and Conventional Surfactants: Influence of Spacer Length and Temperature  

Microsoft Academic Search

Mixed micellar behavior of gemini surfactant butanediyl-1,4-bis(dimethyldodecylammonium bromide) (12-4-12) with conventional surfactant tetradecyl trimethylammonium bromide (TTAB) has been studied in aqueous and in aqueous polyvinyl pyrrolidone (PVP) solutions at various temperatures (288.15, 298.15, 308.15 and 318.15 K) using conductometric method. The behavior of the mixed system has been analyzed in light of Rubingh's regular solution theory. The study indicates that the

T. S. Banipal; A. K. Sood; Jobanpreet Kaur

2012-01-01

94

Effects of Surfactant Carbon-Chain Length on the Phase Behaviors of ATPS  

Microsoft Academic Search

The phase behaviors and properties of alkyl trimethyl ammonium bromide with different carbon-chain length\\/sodium dodecyl sulfate (SDS)\\/NaBr\\/H2O systems at the total surfactant concentration of 0.1 mol · L at 333 K were investigated. The experimental results indicate that the phase behaviors of different systems have similar distributing rules. The carbon-chain length of cationic surfactant can influence the position of aqueous two-phase system region, especially

Hong-ni Teng; Lin-shan Hu; Yong Chen; Cui-ying Yang; Ting-ting Du

2011-01-01

95

Screening of mixed surfactant systems: Phase behavior studies and CT imaging of surfactant-enhanced oil recovery experiments  

Microsoft Academic Search

A systematic chemical screening study was conducted on selected anionic-nonionic and nonionic-nonionic systems. The objective of the study was to evaluate and determine combinations of these surfactants that would exhibit favorable phase behavior and solubilization capacity. The effects of different parameters including (a) salinity, (b) temperature, (c) alkane carbon number, (c) hydrophilic\\/lipophilic balance (HLB) of nonionic component, and (d) type

F. M. Llave; B. L. Gall; P. B. Lorenz; I. M. Cook; L. J. Scott

1993-01-01

96

Yielding and Flow in Adhesive and Nonadhesive Concentrated Emulsions  

NASA Astrophysics Data System (ADS)

The nonlinear rheological response of soft glassy materials is addressed experimentally by focusing on concentrated emulsions where interdroplet attraction is tuned through varying the surfactant content. Velocity profiles are recorded using ultrasonic velocimetry simultaneously to global rheological data in the Couette geometry. Our data show that nonadhesive and adhesive emulsions have radically different flow behaviors in the vicinity of yielding: while the flow remains homogeneous in the nonadhesive emulsion and the Herschel-Bulkley model for a yield stress fluid describes the data very accurately, the adhesive system displays shear localization and does not follow a simple constitutive equation, suggesting that the mechanisms involved in yielding transitions are not universal.

Bécu, Lydiane; Manneville, Sébastien; Colin, Annie

2006-04-01

97

Yielding and flow in adhesive and nonadhesive concentrated emulsions.  

PubMed

The nonlinear rheological response of soft glassy materials is addressed experimentally by focusing on concentrated emulsions where interdroplet attraction is tuned through varying the surfactant content. Velocity profiles are recorded using ultrasonic velocimetry simultaneously to global rheological data in the Couette geometry. Our data show that nonadhesive and adhesive emulsions have radically different flow behaviors in the vicinity of yielding: while the flow remains homogeneous in the nonadhesive emulsion and the Herschel-Bulkley model for a yield stress fluid describes the data very accurately, the adhesive system displays shear localization and does not follow a simple constitutive equation, suggesting that the mechanisms involved in yielding transitions are not universal. PMID:16712042

Bécu, Lydiane; Manneville, Sébastien; Colin, Annie

2006-04-03

98

Anomalous behavior during leveling of thin coating layers with surfactant  

SciTech Connect

Our recently-published linear analysis [Schwartz {ital et} {ital al}., Langmuir {bold 11}, 3690 (1995)] demonstrated that an initially rippled thin layer of Newtonian liquid with uniformly distributed surfactant may level in unexpected ways. While the presence of surfactant will, in general, slow the rate of leveling compared to that of a perfectly clean system, there was shown to exist a realistic parameter range where increasing, rather than reducing, the amount of surfactant present will hasten leveling. Here, for the two-dimensional problem, we investigate the importance of nonlinearity though numerical solution of (i) the unsteady lubrication form of the evolution equations with surfactant, and (ii) finite-element solution of the exact governing equations for slow viscous flow. Confirmation of the linear results is demonstrated and quantitative discrepancy only appears for large-amplitude and short-wavelength ripples. Surface tension gradient driven flow explains the anomalies; for moderate surfactants, the surface quickly {open_quote}hardens,{close_quote} leading to a decay rate of one-quarter of the clean-surface rate, while for weak surfactants, leveling proceeds to a plateau level which decays much slower than the hard-surface result. {copyright} {ital 1996 American Institute of Physics.}

Schwartz, L.W.; Cairncross, R.A.; Weidner, D.E. [Department of Mechanical Engineering, University of Delaware, Newark, Delaware 19716 (United States)

1996-07-01

99

Project blob: Edible emulsions  

Microsoft Academic Search

Most blobs are emulsions. From a chemistry perspective, emulsions turn two liquid phases into what appears to be one continuous phase through the use of surfactants. This lesson, created by a chemical engineering graduate student, allows the secondary students to observe this phenomenon in the transformation of vinegar, oil, and egg yolks into mayonnaise. The students, juniors at Western Hills

Amina Darwish; Mary Ann Schnieders; Andrea Burrows; Anant Kukreti; Stephen Thiel

2011-01-01

100

Multiple emulsions: an overview.  

PubMed

Multiple emulsions are complex polydispersed systems where both oil in water and water in oil emulsion exists simultaneously which are stabilized by lipophillic and hydrophilic surfactants respectively. The ratio of these surfactants is important in achieving stable multiple emulsions. Among water-in-oil-in-water (w/o/w) and oil-in-water-in-oil (o/w/o) type multiple emulsions, the former has wider areas of application and hence are studied in great detail. Formulation, preparation techniques and in vitro characterization methods for multiple emulsions are reviewed. Various factors affecting the stability of multiple emulsions and the stabilization approaches with specific reference to w/o/w type multiple emulsions are discussed in detail. Favorable drug release mechanisms and/or rate along with in vivo fate of multiple emulsions make them a versatile carrier. It finds wide range of applications in controlled or sustained drug delivery, targeted delivery, taste masking, bioavailability enhancement, enzyme immobilization, etc. Multiple emulsions have also been employed as intermediate step in the microencapsulation process and are the systems of increasing interest for the oral delivery of hydrophilic drugs, which are unstable in gastrointestinal tract like proteins and peptides. With the advancement in techniques for preparation, stabilization and rheological characterization of multiple emulsions, it will be able to provide a novel carrier system for drugs, cosmetics and pharmaceutical agents. In this review, emphasis is laid down on formulation, stabilization techniques and potential applications of multiple emulsion system. PMID:17076645

Khan, Azhar Yaqoob; Talegaonkar, Sushama; Iqbal, Zeenat; Ahmed, Farhan Jalees; Khar, Roop Krishan

2006-10-01

101

Poly(ethylene glycol) hydroxystearate-based nanosized emulsions: effect of surfactant concentration on their formation and ability to solubilize quercetin.  

PubMed

Quercetin is a natural compound that has shown several biological activities. However, it displays poor water solubility and, therefore, low bioavailability. In this study, oil-in-water nanosized emulsions were obtained by the hot solvent diffusion method, using castor oil as oily phase and poly(ethylene glycol) (660)-12-hydroxystearate (PEG 660-stearate) and lecithin as surfactants. The effect of the PEG 660-stearate concentration on the droplet size of the nanosized emulsions and on the ability of these systems to load quercetin was investigated. Dynamic light scattering (DLS), transmission electron microscopy (TEM), cryo-TEM, and small-angle X-ray scattering (SAXS) were used to characterize the systems. We have demonstrated that a critical concentration of PEG 660-stearate (2.5 wt%) was needed to obtain colloidal dispersions displaying microemulsion characteristics. This colloidal dispersion, that was not optically birefringent, was constituted by a monodisperse population of 20 nm-large droplets, and exhibited excellent stability. Besides, this system was able to solubilize five times more quercetin than nanoemulsions prepared using 0.25 wt% PEG 660-stearate. SAXS results suggest that the spherical droplets have a core-shell structure. With regard to the hot solvent diffusion method, both diffusion of the solvent towards the aqueous phase and increase of the temperature above the phase inversion temperature (PIT) of PEG 660-stearate appeared to be required for obtaining clear and isotropic colloidal dispersions. PMID:22515071

Dora, Cristiana L; Silva, Luis F C; Putaux, Jean-Luc; Nishiyama, Yoshiharu; Pignot-Paintrand, Isabelle; Borsali, Redouane; Lemos-Senna, Elenara

2012-04-01

102

BEHAVIOR OF ENHANCED CHEMILUMINESENCE PEROXIDASE-CATALYZED PEROXIDATION OF LUMINOL IN THE SYSTEM OF SURFACTANT{WATER{ORGANIC SOLVENT  

Microsoft Academic Search

This work includes some observations of the chemiluminescent reaction behavior in the system surfactant (Triton X-100 and Aerosol OT) -water-organic solvent (octane and hexane). The HRP-chemiluminescent activity was detected without the surfactant or using low surfactant concentration (less than 0.01 M). The greatest activity was ob- served applying the surfactant at 0.001 M. It was demonstrated that in the system

A. D. Ilyina; B. J. E. Mauricio; S. I. P. Sifuentes; H. J. L. Mart; E. S. Bogatcheva; G. J. Romero; M. J. Rodr

103

Phase behavior of supercritical CO 2 microemulsion with food-grade surfactant AOT  

Microsoft Academic Search

Phase behavior of scCO2 microemulsion formed with food grade surfactant sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) was studied. Critical microemulsion\\u000a concentration (c?c) was deduced from the dependence of pressure of cloud points on the concentration of surfactant AOT at\\u000a constant temperature and water concentration. The results show that there are transition points on the cloud point curve in\\u000a a very narrow range

Yongsheng Zhou; Xueqin An; Weiguo Shen; Yinghua Zhang

2006-01-01

104

The spreading and superspeading behavior of new glucosamide-based trisiloxane surfactants on hydrophobic foliage  

Microsoft Academic Search

In order to find how the molecular structure and HLB (hydrophilic–lipophilic balance) value of trisiloxane surfactant affect its wetting and spreading behavior on leaf surface, the time-dependent and the concentration-dependent spreading performance of five new glucosamide-based trisiloxane surfactants on wheat and cabbage leaf surface were investigated and compared with that of Silwet L-77®. The effect of different epicuticular waxes on

Yue Zhang; Gaoyong Zhang; Fu Han

2006-01-01

105

Stability and phase behavior of mixed surfactant vesicles  

NASA Astrophysics Data System (ADS)

Although large, spherical surfactant vesicles are generally unstable to either lamellar or micellar phases, mixtures of two surfactants can lead to spontaneous vesicle formation. We show theoretically how the energetic stabilization of mixed vesicles can occur by considering the curvature elasticity of the surfactant bilayer. Interactions between the two species (of the proper sign and magnitude) are crucial to stabilizing these vesicles. These interactions lead to composition asymmetries and effective spontaneous curvatures of the inner and outer layers that are of equal and opposite signs. The vesicles have a Gaussian distribution about an average size determined by the effective spontaneous curvature; the width of the distribution is calculated as a function of concentration. The stability of these vesicles with respect to a flat lamellar phase is estimated. The predictions of the ranges of stability of the various phases as a function of the three concentrations (solvent, e.g., water-and the two amphiphiles) are in qualitative agreement with recent experiments.

Safran, S. A.; Pincus, P. A.; Andelman, David; Mackintosh, F. C.

1991-01-01

106

Phase behavior and molecular thermodynamics of coacervation in oppositely charged polyelectrolyte/surfactant systems: a cationic polymer JR 400 and anionic surfactant SDS mixture.  

PubMed

Coacervation in mixtures of polyelectrolytes and surfactants with opposite charge is common in nature and is also technologically important to consumer health care products. To understand the complexation behavior of these systems better, we combine multiple experimental techniques to systematically study the polymer/surfactant binding interactions and the phase behavior of anionic sodium dodecyl sulfate (SDS) surfactant in cationic JR 400 polymer aqueous solutions. The phase-behavior study resolves a discrepancy in the literature by identifying a metastable phase between the differing redissolution phase boundaries reported in the literature for the surfactant-rich regime. Isothermal titration calorimetry analyzed within the framework of the simple Satake-Yang model identifies binding parameters for the surfactant-lean phase, whereas a calculation for polymer-bound micelles coexisting with free micelles is analyzed in the surfactant-rich redissolution regime. This analysis provides a preliminary understanding of the interactions governing the observed phase behavior. The resulting thermodynamic properties, including binding constants and the molar Gibbs free energies, enthalpies, and entropies, identify the relative importance of both hydrophobic and electrostatic interactions and provide a first approximation for the corresponding microstructures in the different phases. Our study also addresses the stability and metastability of oppositely charged polyelectrolytes and surfactant mixtures. PMID:22769434

Li, Dongcui; Kelkar, Manish S; Wagner, Norman J

2012-07-06

107

Effect of surfactant on the formation and dissociation kinetic behavior of methane hydrate  

Microsoft Academic Search

The effects of anionic surfactant sodium dodecyl sulfate (SDS) on the formation\\/dissociation kinetic behaviors of methane hydrate have been studied experimentally, with an emphasis put on dissociation kinetic behavior below ice point. The experimental results on hydrate formation show that the formation rates of methane hydrate could be speeded up by adding SDS to water and a critical SDS concentration

W. Lin; G.-J. Chen; C.-Y. Sun; X.-Q. Guo; Z.-K. Wu; M.-Y. Liang; L.-T. Chen; L.-Y. Yang

2004-01-01

108

Critical evaluation of micellization behavior of nonionic surfactant MEGA 10 in comparison with ionic surfactant tetradecyltriphenylphosphonium bromide studied by microcalorimetric method in aqueous medium.  

PubMed

The micellization behavior of MEGA 10 has been studied at nine different temperatures by isothermal titration calorimetry (ITC), and thermodynamics of the process have been evaluated and examined in detail. The aggregation number of the nonionic surfactant has been estimated from the ITC results by a simulation procedure based on the mass action principle of micellization of the surfactant. The cmc of MEGA 10 has shown a minimum in temperature dependence as observed for ionic surfactants. For a comparison, the cmc and related thermodynamic parameters of an ionic surfactant, tetradecyltriphenylphosphonium bromide (C(14)TPB) studied at several temperatures in aqueous medium has been considered. The contributions of the headgroups of both the surfactants to the free energies of their respective micellization have been deciphered and presented. PMID:16706433

Prasad, Madhumita; Chakraborty, Indranil; Rakshit, Animesh K; Moulik, Satya P

2006-05-25

109

Surfactant Behavior and Application with a Brine-Based Remediation Technology  

NASA Astrophysics Data System (ADS)

With the general inability of existing groundwater remediation techniques to efficiently remove dense nonaqueous phase liquids (DNAPLs) from the subsurface, a novel strategy known as the Brine-Based Remediation Technology (BBRT), which relies upon a brine barrier to control downward migration of DNAPL after exposure to an interfacial tension reducing surfactant, has been proposed as a potential alternative to currently used remedial strategies. The choice of surfactants is a challenging problem and much effort has been devoted to screening of surfactants for DNAPL systems. However, due to the sensitivity of many of these surfactant solutions to electrolyte concentrations, they are unsuitable for BBRTs due to the presence of a high concentration brine. Therefore, it is necessary to characterize and evaluate potential surfactant formulations that possess favorable phase behavior, do not precipitate in the presence of high concentration brines, perform favorably in subsurface systems, (i.e., low viscosities and limited losses due to sorption), and effectively reduce interfacial tension to levels required for mobilization. Batch reactor studies were performed that identified surfactant formulations that did not precipitate in solutions containing high concentrations of calcium bromide brine and that possessed favorable phase behavior. The best behaved formulations contained a mixture of a nonionic surfactant, Triton X-100, and an anionic surfactant, Aerosol MA-80. Sorption of one of these mixtures was evaluated in experiments conducted in batch and one-dimensional column reactors. The ability of the mixture to mobilize tetrachloroethylene was evaluated in column experiments. The mixture was used in a BBRT demonstration at the Dover National Test Site in Dover, DE, where a test cell was contaminated with tetrachloroethylene.

Pedit, J. A.; Sanderson, P. M.; Johnson, D. N.; Miller, C. T.

2006-12-01

110

Unique liquid crystal behavior in water of anionic fluorocarbon-hydrocarbon hybrid surfactants containing oxyethylene units.  

PubMed

This study reports the unique aqueous lyotropic liquid crystal behavior of an anionic hybrid surfactant, 8F-B2ES, which has 2-[2-(butyloxy)ethyloxy]ethyl and 1H,1H,2H,2H-perfluorodecyl tails. An 8F-B2ES-analog hybrid surfactant with no oxyethylene units (8F-DeS) and a symmetric fluorinated double-tail surfactant with two 2-(1H,1H,2H,2H-perfluorohexyloxy)ethyl tails (4FEOS) were used as control surfactants in examining the effects of the oxyethylene units and of the hybrid structure on the liquid crystal behavior. Polarized microscopic observations showed the formation of a lamellar liquid crystal phase for each surfactant/water mixture at surfactant concentrations higher than 10 wt.%. In the case of the 30 wt.% 8F-B2ES/water mixture, two types of spherical aggregates were observed at temperatures higher than 40 °C: one was a typical lamella liquid crystal with a maltese cross-texture, and the other was optically isotropic. Interestingly, when the 8F-B2ES lamellar phase was cooled to below 40 °C, the lamellar aggregates were distorted and the isotropic droplets became anisotropic. As this unique liquid crystal behavior was not observed for aqueous mixtures of the control surfactants, the oxyethylene units in the hybridized hydrocarbon tail play an important role in the behavior. This study also examined the effect of the oxyethylene units on microenvironmental polarity in the hybrid surfactant bilayer via fluorescence spectral measurements of pyrene solubilized in each lamellar phase. The polarity of the 8F-B2ES bilayer at 70 °C was found to be that of a hydrocarbon surfactant lamellar phase, and increased gradually with decreasing temperature. The polarity became the same as that of hydrophilic spherical micelles below 40 °C, despite the presence of the lamellar aggregates. Since the polarity in the 8F-DeS bilayer was independent of temperature, and as low as that of a typical hydrocarbon surfactant bilayer, hydration of the 8F-B2ES oxyethylene units would increase the polarity, and then loosen the 8F-B2ES packing within the bilayer. This probably led to distortion of the lamellar aggregates. PMID:21402384

Sagisaka, Masanobu; Fujita, Yoshie; Shimizu, Yusuke; Osanai, Chie; Yoshizawa, Atsushi

2011-02-15

111

Re-entrant phase behavior of a concentrated anionic surfactant system with strongly binding counterions.  

PubMed

The phase behavior of the anionic surfactant sodium dodecyl sulfate (SDS) in the presence of the strongly binding counterion p-toluidine hydrochloride (PTHC) has been examined using small-angle X-ray diffraction and polarizing microscopy. A hexagonal-to-lamellar transition on varying the PTHC to SDS molar ratio (alpha) occurs through a nematic phase of rodlike micelles (Nc) --> isotropic (I) --> nematic of disklike micelles (N(D)) at a fixed surfactant concentration (phi). The lamellar phase is found to coexist with an isotropic phase (I') over a large region of the phase diagram. Deuterium nuclear magnetic resonance investigations of the phase behavior at phi = 0.4 confirm the transition from N(C) to N(D) on varying alpha. The viscoelastic and flow behaviors of the different phases were examined. A decrease in the steady shear viscosity across the different phases with increasing alpha suggests a decrease in the aspect ratio of the micellar aggregates. From the transient shear stress response of the N() and N(D) nematic phases in step shear experiments, they were characterized to be tumbling and flow aligning, respectively. Our studies reveal that by tuning the morphology of the surfactant micelles strongly binding counterions modify the phase behavior and rheological properties of concentrated surfactant solutions. PMID:19301881

Ghosh, Sajal Kumar; Rathee, Vikram; Krishnaswamy, Rema; Raghunathan, V A; Sood, A K

2009-08-01

112

Phase behavior of nonionic surfactant\\/oil\\/water systems containing light alkanes  

Microsoft Academic Search

The phase behavior of nonionic ethoxylate surfactant\\/light alkane\\/water systems is reported in detail. In compressible liquids such as propane, phase transitions which are normally induced by changing temperature or salinity can also be accomplished with pressure. A complete transition from a lower to middle to upper phase microemulsion with pressure is reported for the first time in propane. Widely accepted

Gregory J. McFann; Keith P. Johnston

1993-01-01

113

Non-iterative phase behavior model with application to surfactant flooding and limited compositional simulation  

Microsoft Academic Search

Hand's method is typically used to empirically calculate the equilibrium compositions for ternary systems between two liquid phases. Oil field application of Hand's method is generally limited to surfactant phase behavior with oil and brine, primarily because the excess oil and brine phases are nearly immiscible. Hand's method is not accurate to represent liquid–vapor equilibrium, especially as oil and gas

M. Roshanfekr; Y. Li; R. T. Johns

2010-01-01

114

Method for the resolution of enhanced oil recovery emulsions  

SciTech Connect

An oil-in-water emulsion of crude oil, water and hydrophilic surfactant is resolved by first heating said emulsion until it separates into a surfactant laden water layer and an oil-rich emulsion layer, removing the water layer from the oil-rich emulsion layer, treating the emulsion layer by the addition of from 20 to 40 volume percent of water containing a demulsifier and recovering the crude oil which separates from the water upon standing.

Shaw, D.L.

1984-04-24

115

Visible light-induced surfactant-free emulsion polymerization using camphorquinone/tertiary amine as the initiating system for the synthesis of amine-functionalized colloidal nanoparticles.  

PubMed

A visible light-induced surfactant-free emulsion polymerization (SFEP) was developed as an alternative pathway for the preparation of amine-functionalized nanoparticles by using the photo-initiating system consisting of camphorquinone coupled with tertiary amine (CQ/3°-amine). Water-soluble macromolecules containing 3°-amines were used as the sources of 3°-amine species, which not only function with CQ to generate initiating free radicals, but also provide colloidal stabilization to the resulting colloidal products. The prepared nanoparticles showed uniformed size distribution and good colloidal stability with positively charged surface. For SFEP induced by CQ/polyethyleneimine (PEI) photo-redox couple, the polymerization of methyl methacrylate (MMA) was affected by both light intensity and initiator concentration. In addition, to obtain higher solid content products, the weight ratio of PEI:MMA=1:4 was employed. Finally, an opportunity for immobilizing various amine containing polymers by our photo-induced SFEP was evaluated. The achievement of this SFEP also depended on 3°-amine content of the macromolecules used. PMID:23978285

Ratanajanchai, Montri; Tanwilai, Dolphawan; Sunintaboon, Panya

2013-08-06

116

Influence of alcohols and alkanes on the aggregation behavior of ionic surfactants in water  

SciTech Connect

The influence of alkanes and medium- and long-chain alcohols on the aggregation behavior of ionic surfactants is investigated by fluorescence quenching. The aggregation number of the surfactant is observed to increase dramatically upon addition of alkanes. The influence of added alcohols, however, depends on the chain length. Except butanol, which decreases the size of the aggregate, addition of higher alcohols (from heptanol to decanol) leads to an increase of the size of the micellar aggregate. Addition of alcohols (from butanol to decanol) leads to an expansion of the hydrophobic region of the aggregate and to a promotion of the diffusion process in the interface of the aggregate.

Reekmans, S.; Luo, Hongwen; Van der Auweraer, M.; De Schryver, F.C. (Universiteit Leuven, Heverlee (Belgium))

1990-03-01

117

Adsorption and Aggregation behaviors of tetrasiloxane-tailed gemini surfactants with (EO)m spacers.  

PubMed

Adsorption and aggregation behaviors of novel tetrasiloxane-tailed gemini surfactants N,N'-ditetrasiloxane-N,N'-digluconamide oligo ethylene glycol diglycidyl (Si-m-Si, where m is the number of ethylene glycol of 1, 2, and 3) were investigasted using surface tension, bromophenol blue encapsulation, dynamic light scattering (DLS), and transmission electron microscope (TEM) methods. The static surface tension of the aqueous Si-m-Si solutions measured at the critical aggregate concentration (CAC) was observed to be lower than that of traditional hydrocarbon gemini surfactants. This suggests that these newly synthesized gemini surfactants are capable of forming a closely packed monolayer film at the air/aqueous solution interface. With a combination of DLS data, TEM measurements, and bromophenol blue entrapment studies, formations of vesicles in Si-m-Si solutions appear to occur at a concentration well above the CAC. Moreover, the size of vesicles depended on their m values. PMID:23438340

Guoyong, Wang; Wenshan, Qu; Zhiping, Du; Wanxu, Wang; Qiuxiao, Li

2013-03-06

118

Produced Fluid Emulsions. Final Report.  

National Technical Information Service (NTIS)

Emulsion production and stabilization may be due to one or more of several phenomenon including water-oil ratio, oil and brine chemistry, and surfactant and polymer type and concentration. They may influence emulsification either independently or with dep...

C. F. Hurley A. Himmelblau L. Trom

1984-01-01

119

Chitosan macroporous foams obtained in highly concentrated emulsions as templates.  

PubMed

Emulsion templating is an effective route for the preparation of macroporous polymer foams, with well-defined pore structures. This kind of material is usually obtained by polymerization or crosslinking in the external phase of highly concentrated emulsions. The present article describes the synthesis of macroporous foams based on a cationic polymer, chitosan, crosslinked with genipin, a natural crosslinker. The phase behavior was used to study the influence of chitosan on surfactant self-aggregation. Hexagonal and lamellar liquid crystalline structures could be obtained in the presence of chitosan, and polymer did not greatly influence the geometric lattice parameters of these self-aggregates. O/W highly concentrated emulsions were obtained in the presence of chitosan in the continuous phase, which allowed reducing both droplet size and polydispersity. The emulsions were stable during the time required for crosslinking, obtaining macroporous foams with high pore volume and degree of crosslinking. PMID:24011788

Miras, Jonathan; Vílchez, Susana; Solans, Conxita; Esquena, Jordi

2013-08-12

120

Behavior of papain in mixed micelles of anionic–cationic surfactants having similar tails and dissimilar head groups  

Microsoft Academic Search

The mixed micellar behavior of anionic surfactant, sodium dodecylsulfate (SDS) and cationic surfactant, dodecylethyldimethylammonium bromide (DDAB) at varying mole fractions of DDAB, i.e. ?DDAB in aqueous solution of papain has been investigated with the aid of spectroscopy and physiochemical measurements. Thermodynamic parameters have been computed over the entire mole fraction range of DDAB. The Clint equation and the regular approximation

S. K. Mehta; Bhawna; Ganga Ram

2010-01-01

121

Spontaneous emulsification of oil drops containing surfactants and medium-chain alcohols  

Microsoft Academic Search

Spontaneous emulsification of mixtures of n-hexadecane, n-octanol, and the pure nonionic surfactant C12E6 brought into contact with water was observed using videomicroscopy. Relevant aspects of equilibrium phase behavior in this\\u000a system were determined, and information on emulsion drop size and stability was obtained by turbidity measurements. It was\\u000a found that small, uniform oil droplets and the most stable emulsions occurred

M. Rang; C. Miller

122

Surfactants for well stimulation  

Microsoft Academic Search

Applications of surface-active agents as related to oil and gas well stimulation are reviewed. Particular emphasis is given to the use of surfactants in acidizing operations of limestone and dolomite reservoirs. Surfactants are used to retard the reaction rate of acid on carbonate rocks, to inhibit corrosion of steel, to prevent and break acid-oil emulsions and sludge formation, to suspend

B. E. Hall; R. M. Lasater

1970-01-01

123

Investigation of colloidal properties of modified silicone polymers emulsified by non-ionic surfactants.  

PubMed

Functionalized silicones are a unique class of hybrid materials due to their simultaneous hydrophobic-oleophobic properties, which results in applications in a variety of surface modification techniques. Prior research has shown that changes in surface charge and turbidity of modified silicone emulsions as a function of pH have a marked effect on their performance in coating applications. The emulsion droplet size is also believed to play significant role in such coating applications. In this work, modified silicone polymer emulsions stabilized by non-ionic surfactants were studied using dynamic light scattering (dilute) and electroacoustic (concentrated) spectroscopy to monitor the emulsion droplet size. The dilute and concentrated regime studies showed the emulsion droplet to be in nanometer range with no appreciable change in size as a function of pH. Electroacoustic studies showed a small fraction of droplets to be present in the micron size range. The emulsions were examined using Cryo-TEM technique, and the effect of pH and dilution on hydrophobicity of nanodomains was studied by employing fluorescence spectroscopy. It is shown from pyrene excimer behavior that both the dilution and pH have an effect on emulsion stability with a presence of critical surfactant concentration after which the emulsion was destabilized. It is proposed that the emulsion stability characteristics and the particle size distribution both play a significant role in their ability to impart desired macro and nano surface properties to treated substrates through electrostatic interactions and selective binding. PMID:22796069

Purohit, Parag S; Kulkarni, Ravi; Somasundaran, P

2012-06-18

124

Water-in-oil emulsions stabilized by water-dispersible poly(N-isopropylacrylamide) microgels: understanding anti-Finkle behavior.  

PubMed

Emulsions were prepared using poly(N-isopropylacrylamide) microgels as thermoresponsive stabilizers. The latter are well-known for their sensitivity to temperature: they are swollen by water below the so-called volume phase transition temperature (VPTT = 33 °C) and shrink when heated above it. Most of the studies reported in the literature reveal that the corresponding emulsions are of the oil-in-water type (O/W) and undergo fast destabilization upon warming above the VPTT. In the present study, whereas O/W emulsions were obtained with a wide panel of oils of variable polarity and were all thermoresponsive, water-in-oil (W/O) emulsions were found only in the presence of fatty alcohols and did not exhibit any thermal sensitivity. To understand the peculiar behavior of emulsions based on fatty alcohols, we investigated the organization of microgels at the oil-water interface and we studied the interactions of pNIPAM microgels with octanol. By combining several microscopy methods and by exploiting the limited coalescence process, we provided evidence that W/O emulsions are stabilized by multilayers of nondeformed microgels located inside the aqueous drops. Such behavior is in contradiction with the empirical Finkle rule stating that the continuous phase of the preferred emulsion is the one in which the stabilizer is preferentially dispersed. The study of microgels in nonemulsified binary water/octanol systems revealed that octanol diffused through the aqueous phase and was incorporated in the microgels. Thus, W/O emulsions were stabilized by microgels whose properties were substantially different from the native ones. In particular, after octanol uptake, they were no longer thermoresponsive, which explained the loss of responsiveness of the corresponding W/O emulsions. Finally, we showed that the incorporation of octanol modified the interfacial properties of the microgels: the higher the octanol uptake before emulsification, the lower the amount of particles in direct contact with the interface. The multilayer arrangement was thus necessary to ensure efficient stabilization against coalescence, as it increased interface cohesiveness. We discussed the origin of this counterexample of the Finkle's rule. PMID:22017481

Destribats, Mathieu; Lapeyre, Véronique; Sellier, Elisabeth; Leal-Calderon, Fernando; Schmitt, Véronique; Ravaine, Valérie

2011-11-11

125

Transitional phase inversion of emulsions monitored by in situ near-infrared spectroscopy.  

PubMed

Water-heptane/toluene model emulsions were prepared to study emulsion transitional phase inversion by in situ near-infrared spectroscopy (NIR). The first emulsion contained a small amount of ionic surfactant (0.27 wt % of sodium dodecyl sulfate) and n-pentanol as a cosurfactant. In this emulsion, the study was guided by an inversion coordinate route based on a phase behavior study previously performed. The morphology changes were induced by rising aqueous phase salinity in a "steady-state" inversion protocol. The second emulsion contained a nonionic surfactant (ethoxylated nonylphenol) at a concentration of 3 wt %. A continuous temperature change induced two distinct transitional phase inversions: one occurred during the heating of the system and another during the cooling. NIR spectroscopy was able to detect phase inversion in these emulsions due to differences between light scattered/absorbed by water in oil (W/O) and oil in water (O/W) morphologies. It was observed that the two model emulsions exhibit different inversion mechanisms closely related to different quantities of the middle phases formed during the three-phase behavior of Winsor type III. PMID:23656562

Charin, R M; Nele, M; Tavares, F W

2013-05-08

126

SURFACTANT-OIL-WATER SYSTEMS NEAR THE AFFINITY INVERSION PART IX : OPTIMUM FORMULATION AND PHASE BEHAVIOR OF MIXED ANIONIC-CATIONIC SYSTEMS  

Microsoft Academic Search

Mixtures of anionic (SDS) and cationic (TTAB) surfactants exhibit a phase behavior which may be interpreted as a mixture of the equimolecular compound with the surfactant which is in excess.The optimum formulation for three-phase behavior of anionic-cationic mixture-oil-brine-alcohol systems follows a linear mixing rule up to 25 % of any of the surfactants.When both surfactants are in the concentration mid-range

R. E. Antón; D. Gómez; A. Graciaa; J. Lachaise; J. L. Salager

1993-01-01

127

Synthesis and characterization of palm oil alkyd emulsions  

Microsoft Academic Search

This paper describes the preparation of palm oil alkyd emulsions. The palm oil alkyds were first synthesized by fusion cooks by using palm kernel oil (PKO), phthalic anhydride (PA) and glycerol (Gly). The resulting alkyds were then converted into emulsions through emulsion inversion point (EIP) method by adding water and surfactants. These emulsions could be blended with natural rubber (NR)

Lee Siang Yin; Gan Seng Neon

128

Preparation of poly( N-isopropylacrylamide) emulsion gels and their drug release behaviors  

Microsoft Academic Search

Stimuli-sensitive drug delivery systems (DDSs) have attracted considerable attention in medical and pharmaceutical fields; thermosensitive DDS dealing with poly(N-isopropylacrylamide) (poly(NIPA)) have been widely studied. Novel NIPA emulsion gels, i.e., NIPA hydrogels containing distributed oil (oleyl alcohol) microdroplets, were synthesized by means of an emulsion-gelation method in which the polymerization of hydrogels in an aqueous phase in an oil-in-water (O\\/W) emulsion

Hideaki Tokuyama; Yuya Kato

2008-01-01

129

Influence of Incorporation Methods on Partitioning Behavior of Lipophilic Drugs into Various Phases of a Parenteral Lipid Emulsion  

PubMed Central

The purpose of this study was to investigate the effect of drug incorporation methods on the partitioning behavior of lipophilic drugs in parenteral lipid emulsions. Four lipophilic benzodiazepines, alprazolam, clonazepam, diazepam, and lorazepam, were used as model drugs. Two methods were used to incorporate drugs into an emulsion: dissolving the compound in the oil phase prior to emulsification (de novo emulsification), and directly adding a concentrated solution of drug in a solubilizer to the emulsion base (extemporaneous addition). Based on the molecular structures and determination of the oil and aqueous solubilities and the partition coefficients of the drugs, the lipophilicity was ranked as diazepam > clonazepam > lorazepam > alprazolam. Ultracentrifugation was used to separate the emulsion into four phases, the oil phase, the phospholipid-rich phase, the aqueous phase and the mesophase, and the drug content in each phase was determined. Partitioning of diazepam, which has the highest lipophilicity and oil solubility among the four drugs, was unaffected by the drug incorporation method, with both methods giving a high proportion of drug in the inner oil phase and the phospholipid-rich phase, compared to the aqueous phase and mesophase. Partitioning of the less lipophilic drugs (alprazolam, clonazepam, and lorazepam) in the phases of the emulsion system was dependent on the method of incorporation and the drug solubility properties. Emulsions of the three drugs prepared by de novo emulsification exhibited higher drug localization in the phospholipid-rich phase compared to those made by extemporaneous addition. With the latter method, the drugs tended to localize in the outer aqueous phase and mesophase, with less deposition in the phospholipid-rich phase and no partitioning into the inner oil phase.

Sila-on, Warisada; Vardhanabhuti, Nontima; Ongpipattanakul, Boonsri

2008-01-01

130

Emulsions stabilised solely by colloidal particles  

Microsoft Academic Search

The preparation and properties of emulsions, stabilised solely by the adsorption of solid particles at the oil–water interface, are reviewed especially in the light of our own work with particles of well-controlled surface properties. Where appropriate, comparison is made with the behaviour of surfactant-stabilised emulsions. Hydrophilic particles tend to form oil-in-water (o\\/w) emulsions whereas hydrophobic particles form water-in-oil (w\\/o) emulsions.

Robert Aveyard; Bernard P Binks; John H Clint

2003-01-01

131

Influence of layer thickness and composition of cross-linked multilayered oil-in-water emulsions on the release behavior of lutein.  

PubMed

Multilayering and enzymatic cross-linking of emulsions may cause alterations in the release behavior of encapsulated core material due to changes in thickness, porosity and permeability of the membrane. An interfacial engineering technology based on the layer-by-layer electrostatic deposition of oppositively charged biopolymers onto the surfaces of emulsion droplets in combination with an enzymatic treatment was used to generate emulsions with different droplet interfaces to test this hypothesis. Release behavior of primary, secondary (coated) and laccase-treated secondary emulsions carrying lutein, an oxygenated carotenoid, was characterized and studied. Fish gelatin (FG), whey protein isolate (WPI) and dodecyltrimethylammonium bromide (DTAB) were used as primary emulsifiers under acidic conditions (pH 3.5) to facilitate the adsorption of a negatively charged biopolymer (sugar beet pectin). Laccase was added to promote cross-linking of adsorbed beet pectin. The release of lutein-loaded emulsions was investigated and quantified by UV-Vis spectrophotometry. Primary WPI-stabilized emulsions showed a five times higher release of lutein after 48 h than secondary emulsions (pH 3.5). Primary DTAB-stabilized emulsions released 7.2% of encapsulated lutein within the observation period, whereas beet pectin-DTAB-coated emulsions released only 0.13% of lutein. Cross-linking of adsorbed pectin did not significantly decrease release of lutein in comparison to non-cross-linked secondary emulsions. Additionally, release of lutein was also affected by changes in the pH of the surrounding medium. Results suggest that modulating the interfacial properties of oil-in-water emulsion by biopolymer deposition and/or cross-linking may be a useful approach to generate food-grade delivery systems that have specific release-over-time profiles of incorporated active ingredients. PMID:23978837

Beicht, Johanna; Zeeb, Benjamin; Gibis, Monika; Fischer, Lutz; Weiss, Jochen

2013-10-25

132

Microemulsion formation and phase behavior of anionic and cationic surfactants with sodium dodecyl sulfate and cetyltrimethylammonium bromide  

SciTech Connect

The phase behavior and solubilization of multiphase microemulsions in mixed anionic-cationic surfactant systems were studied for fixed ratio of water-to-oil and surfactant-to-alcohol. In the mixed surfactants (sodium dodecyl sulfate + cetyltrimethylammonium bromide)/heptane/alcohol/water systems, microemulsions and birefringement phases are formed by adjusting the surfactant ratio {epsilon} and the cationic weight fraction {delta}. The bicontinuous (or w/o microemulsion) {yields} birefringement o/w microemulsion transition takes place and microemulsion domain enlarges with increasing {epsilon}. The optimum surfactant concentration {gamma} increases and the corresponding optimum {delta} decreases with increasing {epsilon} and both of them decrease with increasing the alcohol chain length butanol to hexanol. The birefringent region shrinks rapidly with increasing alcohol and/or CTAB weight fractions in total surfactant concentration. Conductivity measurements have been performed in the single-phase region of the system containing mixed surfactants and alcohols at 25 C. The conductivity results indicate where a transition takes place and which of these different types of phase structures may be in the single-phase of the system containing anionic-cationic mixed surfactants.

Li, X.; Lin, E.; Zhao, G.; Xiao, T. [Northwest Normal Univ., Lanzhou, Gansu (China). Dept. of Chemistry

1996-12-01

133

Impact of fat and water crystallization on the stability of hydrogenated palm oil-in-water emulsions stabilized by a nonionic surfactant.  

PubMed

The influence of (0-40 wt %) sucrose and (0 and 150 mmol/kg) sodium chloride on the physical properties of 20 wt % hydrogenated palm oil-in-water emulsions stabilized by 2 wt % Tween 20 after crystallization of the oil phase only or both the oil and water phases has been examined. Emulsion stability was assessed by differential scanning calorimetry measurements of fat destabilization after cooling-heating cycles and by measurements of mean particle size, percent destabilized fat, and percent free oil obtained from gravitational separation after isothermal storage (at -40 to +37 degrees C). At storage temperatures where the oil phase was partially crystalline and the water was completely liquid, the emulsions were unstable to droplet coalescence and oiling off because of partial coalescence. Both NaCI and sucrose increased the extent of partial coalescence in the emulsions. At storage temperatures where both oil and water crystallized, the emulsions were completely destabilized. The stability of the emulsions to freezing and thawing could be improved somewhat by adding sucrose (>20 wt %). Emulsions stabilized by whey proteins were shown to have better freeze-thaw stability than those stabilized by Tween 20, especially in the presence of sucrose. These results may help formulate food emulsions with improved freeze-thaw stability. PMID:19127730

Thanasukarn, Parita; Pongsawatmanit, Rungnaphar; McClements, D Julian

2006-05-17

134

Molecular fragment dynamics study on the water-air interface behavior of non-ionic polyoxyethylene alkyl ether surfactants.  

PubMed

Molecular fragment dynamics (MFD) is a mesoscopic simulation technique based on dissipative particle dynamics (DPD). MFD simulations of the self-aggregation of the polyoxyethylene alkyl ether surfactants C6E6, C10E6, C12E6 and C16E6 at the water-air surface lead to equilibrium nanoscale structures and computationally determined surface tensions which are in agreement with experimental data for different surfactant concentrations. Thus, molecular fragment dynamics is a well-suited predictive technique to study the behavior of new surfactant systems. PMID:24016746

Truszkowski, Andreas; Epple, Matthias; Fiethen, Annamaria; Zielesny, Achim; Kuhn, Hubert

2013-08-13

135

Polyhydroxy Alcohols and Peach Oil Addition Influence on Liquid Crystal Formation and Rheological Behavior of O\\/W Emulsions  

Microsoft Academic Search

The aim of this study was to develop O\\/W emulsions with a self?emulsifying base (SEB) containing liquid crystals (LC) and evaluate the influence of polyhydroxy alcohols and peach oil addition in liquid crystal formation as well as to analyze the rheological behavior of these systems. Formulations containing SEB were supplemented or not with glycerin, sorbitol, propylene glycol, and\\/or peach oil.

Daniela S. Masson; Gilsane G. Morais; Jacqueline M. de Morais; Fernanda F. de Andrade; Orlando D. H. Dos Santos; Wanderley P. de Oliveira; Pedro A. Rocha Filho

2005-01-01

136

BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS  

SciTech Connect

The aim of the project is to develop a knowledge base to help the design of enhanced processes for mobilizing and extracting untrapped oil. We emphasize evaluation of novel surfactant mixtures and obtaining optimum combinations of the surfactants for efficient chemical flooding EOR processes. In this regard, an understanding of the aggregate shape, size and structure is crucial since these properties govern the crude oil removal efficiency. During the three-year period, the adsorption and aggregation behavior of sugar-based surfactants and their mixtures with other types of surfactants have been studied. Sugar-based surfactants are made from renewable resources, nontoxic and biodegradable. They are miscible with water and oil. These environmentally benign surfactants feature high surface activity, good salinity, calcium and temperature tolerance, and unique adsorption behavior. They possess the characteristics required for oil flooding surfactants and have the potential for replacing currently used surfactants in oil recovery. A novel analytical ultracentrifugation technique has been successfully employed for the first time, to characterize the aggregate species present in mixed micellar solution due to its powerful ability to separate particles based on their size and shape and monitor them simultaneously. Analytical ultracentrifugation offers an unprecedented opportunity to obtain important information on mixed micelles, structure-performance relationship for different surfactant aggregates in solution and their role in interfacial processes. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. Four softwares: OptimaTM XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity experimental data. The results have been compared to that from Light Scattering. Based on the tests, Svedberg and SEDFIT analysis were chosen for further studies.

P. Somasundaran

2004-11-20

137

Effect of calcium salts and surfactant concentration on the stability of water-in-oil (w\\/o) emulsions prepared with polyglycerol polyricinoleate  

Microsoft Academic Search

The objective of this work was to obtain water-in-oil (w\\/o) emulsions with polyglycerol polyricinoleate (PGPR) as emulsifier and to study the effect of the addition of calcium in the dispersed aqueous phase on the stability of these systems. Emulsions were formulated with 0.2, 0.5 and 1.0% w\\/w PGPR and 10% w\\/w water containing calcium chloride at varied concentrations or other

Andrés L. Márquez; Alejandra Medrano; Luis A. Panizzolo; Jorge R. Wagner

2010-01-01

138

Unique aggregation behavior of a carboxylate gemini surfactant with a long rigid spacer in aqueous solution.  

PubMed

A new gemini surfactant with a long and rigid spacer, O,O'-bis(sodium 2-dodecylcarboxylate)-p-dibenzenediol (referred to as C(12)?(2)C(12)), has been synthesized. Its aggregation in aqueous solution has been studied using static and dynamic light scattering measurements. The homologue O,O'-bis(sodium 2-dodecylcarboxylate)-p-benzenediol (C(12)?C(12)) whose spacer only contains a single phenyl group was also examined for comparison. Dynamic light scattering (DLS) revealed the unexpected existence of large aggregates in the solution of C(12)?(2)C(12). However, C(12)?C(12) showed rather normal aggregation behavior. Both the results of intrinsic viscosity and light scattering demonstrated a loose structure for the large aggregates of C(12)?(2)C(12). This behavior was attributed to an extending configuration of C(12)?(2)C(12) with the two alkyl tails stretching toward the solution due to the rigidity of the long spacer. The large network-like aggregate formation was an inevitable outcome of spontaneously reducing the energy of the system. Freeze-fracture transmission electron microscopy (FF-TEM) images and (1)H NMR measurements supported this speculation. Due to the columnar-like molecular geometry, the large network-like aggregates were directly transformed into rodlike micelles with increasing surfactant concentration. Depending on further micellar growth, the wormlike micelles were finally formed as confirmed by rheological measurements. PMID:23244594

Xie, Dan Hua; Zhao, Jianxi

2012-12-31

139

Preparation of poly(N-isopropylacrylamide) emulsion gels and their drug release behaviors.  

PubMed

Stimuli-sensitive drug delivery systems (DDSs) have attracted considerable attention in medical and pharmaceutical fields; thermosensitive DDS dealing with poly(N-isopropylacrylamide) (poly(NIPA)) have been widely studied. Novel NIPA emulsion gels, i.e., NIPA hydrogels containing distributed oil (oleyl alcohol) microdroplets, were synthesized by means of an emulsion-gelation method in which the polymerization of hydrogels in an aqueous phase in an oil-in-water (O/W) emulsion and the loading of a lipophilic drug (indomethacin) dissolved in an oil phase were accomplished simultaneously. The pulsatile (on-off) drug release from the NIPA emulsion gel loading indomethacin to a phosphate buffered saline (PBS) solution was successfully controlled by a temperature swing between 25 degrees C (release off) and 40 degrees C (release on). The mechanism of the pulsatile drug release was discussed in relation to the diffusion rate, distribution ratio, solvent exchange of NIPA hydrogels, and drug release from an NIPA organogel. The mechanism was as follows: the solvent exchange occurred within the NIPA emulsion gel (the NIPA gel-network absorbed oleyl alcohol with indomethacin) at temperatures above the LCST, and the diffusion rate of indomethacin through the solvent-exchanged gel was higher at 40 degrees C than at 25 degrees C. PMID:18790619

Tokuyama, Hideaki; Kato, Yuya

2008-08-14

140

Demulsification of Emulsions Exploited by Enhanced Oil Recovery System  

Microsoft Academic Search

Experimental data are presented to show the influence of the enhanced oil recovery system's components, alkali, surfactant, and polymer, on the demulsification and light transmittance of the water separated from the emulsions. Among which, the effects of surfactants, polyoxyethylene (10) alkylphenol ether (OP?10) and sodium petroleum sulfonate (CY?1) on emulsion stability, are the strongest of any component, the effects of

Lixin Xia; Shiwei Lu; Guoying Cao

2003-01-01

141

Influence of emulsifier on the formation of alkyd emulsions  

Microsoft Academic Search

In traditional alkyd paints, the alkyd is dissolved in an organic solvent such as mineral spirit. For health and environmental reasons there is an increasing interest in water-borne alkyd paints. Alkyd emulsions are therefore an interesting alternative. The alkyd emulsion should have a good colloidal stability at a low concentration of surfactant. A high concentration of surfactant gives undesired properties

M. Hulde´n

1995-01-01

142

Phase behavior and oil recovery investigations using mixed and alkaline-enhanced surfactant systems  

Microsoft Academic Search

The results of an evaluation of different mixed surfactant and alkaline-enhanced surfactant systems for enhanced oil recovery are described. Several mixed surfactant systems have been studies to evaluate their oil recovery potential as well as improved adaptability to different ranges of salinity, divalent ion concentrations, and temperature. Several combinations of screening methods were used to help identify potential chemical formulations

F. M. Llave; B. L. Gall; T. R. French; L. A. Noll; S. A. Munden

1992-01-01

143

Dynamic interfacial behavior between crude oil and octylmethylnaphthalene sulfonate surfactant flooding systems  

Microsoft Academic Search

Experimental investigations have been conducted to explore the fundamental mechanisms for the lowering of dynamic interfacial tension (DIT) between crude oil, offered from Shengli Oil Field in China, and surfactant flooding systems, and the single-component octylmethylnaphthalene sulfonate surfactant, developed in our laboratory, was adopted. It is also found that the added surfactant is more effective and efficient than corresponding conventional

Zhongkui Zhao; Zongshi Li; Weihong Qiao; Lübo Cheng

2005-01-01

144

Pivotal Role of Anionic Phospholipids in Determining Dynamic Behavior of Lung Surfactant  

Microsoft Academic Search

Phosphatidylglycerol (PG) and phosphatidylinositol (PI) are anionic phospholipids (APLs) present in lung surfactant of virtually all species studied, although their specific contribution to function is un- known. This study examines how APLs influence surfactant monolayer stability and adsorption under static and dynamic conditions. Interfacial properties of surfactants reconstituted with native phos- pholipids (PL), and phospholipids devoid of anionic species (DAPL),

EDWARD P. INGENITO; RENE MORA; LENA MARK

2000-01-01

145

Electrochemical behavior of phenol in alkaline media at hydrotalcite-like clay\\/anionic surfactants\\/glassy carbon modified electrode  

Microsoft Academic Search

The electrochemical behavior of phenol, using glassy carbon (GC) modified electrodes containing a hydrotalcite (HT)-like clay and anionic surfactants such as sodium octyl sulfate (SOS), sodium dodecyl sulfate (SDS), or sodium dodecylbenzenesulfonate (SDBS) in alkaline media, has been examined. Phenol oxidation at the modified electrodes, after a time accumulation under open circuit conditions, promotes increments of the current and shifts

L. Fernández; Carlos Borrás; Hermes Carrero

2006-01-01

146

Effect of headgroup chirality in nanoassemblies. 2. Thermal behavior of vitamin C-based surfactants.  

PubMed

l-Ascorbic and d-isoascorbic acids are epimers, and their alkanoyl-esters are surfactant-like in water. These ascorbic acid derivatives retain the same stereogenic configurations of the parent molecules. That circumstance strongly affects their physicochemical properties, both in the solid and in the dispersed states. The thermal behavior of 6-O-l-ascorbyl-dodecanoate (l-ASC12), of 6-O-d-isoascorbyl-dodecanoate (d-ASC12), and of their mixtures was investigated through DSC, XRD, and FTIR experiments. The results indicate that the mixtures of the two epimers produce two eutectics and a 1:1 molecular compound, both in the pure phase and in the coagel state. From the phase diagram data, the activity coefficients of the different species and the main excess thermodynamic functions can be calculated. The results provide insight into the effects of stereochemistry on their intermolecular interactions. PMID:19459600

Lo Nostro, Pierandrea; Ambrosi, Moira; Ninham, Barry W; Baglioni, Piero

2009-06-18

147

Effect of calcium salts and surfactant concentration on the stability of water-in-oil (w/o) emulsions prepared with polyglycerol polyricinoleate.  

PubMed

The objective of this work was to obtain water-in-oil (w/o) emulsions with polyglycerol polyricinoleate (PGPR) as emulsifier and to study the effect of the addition of calcium in the dispersed aqueous phase on the stability of these systems. Emulsions were formulated with 0.2, 0.5 and 1.0% w/w PGPR and 10% w/w water containing calcium chloride at varied concentrations or other salts (calcium lactate or carbonate; sodium, magnesium or potassium chloride). The stability of these systems was studied with a vertical scan analyzer during 15 days; coalescence and sedimentation were observed as simultaneous destabilization processes. The increase of PGPR concentration and/or calcium chloride content gave more stable emulsions. The stabilizing effect of calcium salt was attributed to the diminution of the water droplets size, the decrease of the attractive force between water droplets and the increase of the adsorption density of the emulsifier. The viscoelastic parameters of the interfacial film were decreased with increasing calcium and PGPR concentrations. Calcium chloride produced a higher increase of stability than calcium salts with lower dissociation degree. The presence of any assayed salt in the aqueous phase also allowed the stabilization of w/o emulsions with higher water contents. PMID:19822323

Márquez, Andrés L; Medrano, Alejandra; Panizzolo, Luis A; Wagner, Jorge R

2009-09-18

148

Practical Surfactant Mixing Rules Based on the Attainment of Microemulsion–Oil–Water Three-Phase Behavior Systems  

Microsoft Academic Search

Surfactant mixture are generally used to fine-tune formulations to an exact property value, such as\\u000a changing its hydrophilicity. To do so a precise characterization method has to be used. The presented\\u000a technique consists of the attainment of a microemulsion–oil–water Winsor III three-phase\\u000a behavior in a reference system. It allows one to classify surfactants in a hydrophilicity scale\\u000a with an accuracy equivalent to one tenth

Raquel E. Antón; José M. Andérez; Carlos Bracho; Francia Vejar; Jean-Louis Salager

149

The Effect of Live Crude on Phase Behavior and Oil-Recovery Efficiency of Surfactant Flooding Systems  

Microsoft Academic Search

Neither pressure alone nor pressurizing with methane affects phase behavior of a particular surfactant\\/ brine\\/stock-tank-oil system. Oil-recovery efficiency in corefloods is not significantly different whether the stock-tank oil is pressurized with methane or diluted with iso-octane to the viscosity of the live crude. In contrast, phase behavior and oil-recovery efficiency do change upon methane pressurization when a lower-molar volume synthetic

Richard Nelson

1983-01-01

150

Effect of Cationic Surfactant Head Groups on Synthesis, Growth and Agglomeration Behavior of ZnS Nanoparticles  

NASA Astrophysics Data System (ADS)

Colloidal nanodispersions of ZnS have been prepared using aqueous micellar solution of two cationic surfactants of trimethylammonium/pyridinium series with different head groups i.e., cetyltrimethylammonium chloride (CTAC) and cetyltrimethylpyridinium chloride (CPyC). The role of these surfactants in controlling size, agglomeration behavior and photophysical properties of ZnS nanoparticles has been discussed. UV-visible spectroscopy has been carried out for determination of optical band gap and size of ZnS nanoparticles. Transmission electron microscopy and dynamic light scattering were used to measure sizes and size distribution of ZnS nanoparticles. Powder X-ray analysis (Powder XRD) reveals the cubic structure of nanocrystallite in powdered sample. The photoluminescence emission band exhibits red shift for ZnS nanoparticles in CTAC compared to those in CPyC. The aggregation behavior in two surfactants has been compared using turbidity measurements after redispersing the nanoparticles in water. In situ evolution and growth of ZnS nanoparticles in two different surfactants have been compared through time-dependent absorption behavior and UV irradiation studies. Electrical conductivity measurements reveal that CPyC micelles better stabilize the nanoparticles than that of CTAC.

Mehta, S. K.; Kumar, Sanjay; Chaudhary, Savita; Bhasin, K. K.

2009-10-01

151

Solubility and adsorption behaviors of chlorpyriphos-methyl in the presence of surfactants  

Microsoft Academic Search

In the present work changes in the adsorption of the pesticide chlorpyrifos-methyl (CLP-m) on soil colloids induced by application of surfactants were determined using a batch equilibrium method. The surfactants used were sodium dodecyl sulphate (SDS), Tween 20, and dihexadecyldimethylammonium bromide (DHAB). The adsorption isotherms of CLP-m in aqueous medium and in surfactant solutions at concentration equal to the critical

Mara Gennari; Cristina Messina; Cristina Abbate; Andrea Baglieri; Carlotta Boursier

2009-01-01

152

Zwitterionic heterogemini surfactants containing ammonium and carboxylate headgroups 2: aggregation behavior studied by SANS, DLS, and cryo-TEM.  

PubMed

The aggregation behavior in aqueous solution of zwitterionic heterogemini surfactants, N,N-dimethyl-N-[2-(N'-alkyl-N'-?-carboxypropanoylamino)ethyl]-1-alkylammonium bromides (2C(n)AmCa, in which n represents hydrocarbon chain lengths of 8, 10, 12, and 14), with nonidentical headgroups containing ammonium and carboxylate was investigated through small-angle neutron scattering (SANS), dynamic light scattering (DLS), and cryogenic transmission electron microscopy (cryo-TEM) techniques. We found that the aggregation behavior of 2C(n)AmCa strongly depended on the hydrocarbon chain length and the surfactant concentration. 2C(8)AmCa forms spherical micelles with radius of approximately 2 nm in solution. 2C(10)AmCa forms rod-like micelles at low concentration in the solution, and the structure changes to vesicles with increasing concentration. The membrane thickness of the vesicle is independent of the surfactant concentration. Aggregation shape transitions were also observed for 2C(12)AmCa. In addition, it appears that the vesicles of 2C(12)AmCa coexist with the rod-like micelles at a wide range of surfactant concentrations. Interestingly, 2C(14)AmCa forms vesicles with averaged membrane thickness of 2.32 nm in solution, even at the extremely low concentration of 10 times the cmc. Thus, it was concluded that 2C(n)AmCa exhibits unique aggregation behavior, such as the formation of spherical micelle?rod-like micelle?rod-like micelle+vesicle (coexistence)?vesicle with increasing hydrocarbon chain length and surfactant concentration. We also found that the membrane structure is an interdigitated bilayer when the vesicles are formed. This formation of interdigitated structures is related to the origins of the effective properties of 2C(n)AmCa in solution. PMID:22261272

Nyuta, Kanae; Yoshimura, Tomokazu; Tsuchiya, Koji; Sakai, Hideki; Abe, Masahiko; Iwase, Hiroki

2011-12-19

153

Preparation of positively charged oil\\/water nano-emulsions with a sub-PIT method  

Microsoft Academic Search

The phase inversion temperature (PIT) method is generally used to prepare nonionic surfactant stabilized nano-emulsions because of its low energy and surfactant consumption. The emulsion droplets are usually negatively charged because of the selective adsorption of OH? onto the droplet surfaces. In this work, positively charged oil\\/water nano-emulsions were prepared by adding a cationic surfactant to the system. The cationic

Zhen Mei; Shangying Liu; Lei Wang; Jingjing Jiang; Jian Xu; Dejun Sun

2011-01-01

154

Lubricating Properties of Oil-In-Water Emulsions  

Microsoft Academic Search

Experiments are described in which elastohydrodynamic and boundary lubrication properties of O\\/W emulsions of mineral oil are studied with a variety of nonionic surfactants as the emulsifying agents. The changes in the minimum elastohydrodynamic film thickness are determined with different surfactants, with changes in oil concentration, with changes in emulsifying agent concentration, and with blending of different surfactants. These results

Yoshitsugu Kimura; Kazumi Okada

1989-01-01

155

Nano-emulsions and nanocapsules by the PIT method: an investigation on the role of the temperature cycling on the emulsion phase inversion.  

PubMed

This paper focuses on the phenomenological understanding of temperature cycling process, applied to the phase inversion temperature (PIT) method. The role of this particular thermal treatment on emulsions phase inversion, as well as its ability to generate nano-emulsions have been investigated. In order to propose a general study, we have based our investigations on a given formulation of nano-emulsions classically proposed in the literature [Heurtault, B., Saulnier, P., Pech, B., Proust, J. E., Benoit, J.P., 2002. A novel phase inversion-based process for the preparation of lipid nanocarriers. Pharm. Res. 19, 875; Lamprecht, A., Bouligand, Y, Benoit, J.P., 2002. New lipid nanocapsules exhibit sustained release properties for amiodarone. J. Control. Release 84, 59-68], using a polyethoxylated model nonionic surfactant, a polyoxyehtylene-660-12-hydroxy stearate, stabilizing the emulsion composed of caprilic triglycerides (triglycerides medium chains), salt water (and also phospholipidic amphiphiles neutral for the formulation). Characterization of nano-emulsions was performed by dynamic light scattering (DLS) which provides the hydrodynamic diameter, but also the polydispersity index (PDI), as a fundamental criteria to judge the quality of the dispersion. Another aspect of the characterization was done following the emulsion inversion and structure by electrical conductivity through the temperature scan. Overall, the role such a temperature cycling process on the formulation of nano-emulsions appears to be relatively important, and globally enhanced as the surfactant concentration is lowered. Actually, both the hydrodynamic diameter and the PDI decrease as a function of the number and temperature cycles up to stabilize a steady state. Eventually, such a cycling process allows the generation of nano-emulsions in ranges of compositions largely expanded when compared with the classical PIT method. These general and interesting trends emerge from the results, are discussed and essentially explained by regarding the behavior of the nonionic surfactants towards the water/oil interface, linking partitioning coefficients, temperature variation, and surfactant water/oil interfacial concentration. In that way, this paper proposes new insights into the phenomena governing the PIT method, by originally investigating the temperature cycling process. PMID:17592746

Anton, Nicolas; Gayet, Pascal; Benoit, Jean-Pierre; Saulnier, Patrick

2007-05-06

156

The effect of live crude on phase behavior and oil-recovery efficiency of surfactant flooding systems  

SciTech Connect

Neither pressure alone nor pressurizing with methane affects phase behavior of a particular surfactant/ brine/stock-tank-oil system. Oil-recovery efficiency in corefloods is not significantly different whether the stock-tank oil is pressurized with methane or diluted with iso-octane to the viscosity of the live crude. In contrast, phase behavior and oil-recovery efficiency do change upon methane pressurization when a lower-molar volume synthetic oil is substituted for the stock-tank oil. Some thermodynamic insight regarding the different behavior of the two oils is offered.

Nelson, R.C.

1983-06-01

157

Cyclodextrin stabilised emulsions and cyclodextrinosomes.  

PubMed

We report the preparation of o/w emulsions stabilised by microcrystals of cyclodextrin-oil inclusion complexes. The inclusion complexes are formed by threading cyclodextrins from the aqueous phase on n-tetradecane or silicone oil molecules from the emulsion drop surface which grow further into microrods and microplatelets depending on the type of cyclodextrin (CD) used. These microcrystals remain attached on the surface of the emulsion drops and form densely packed layers which resemble Pickering emulsions. The novelty of this emulsion stabilisation mechanism is that molecularly dissolved cyclodextrin from the continuous aqueous phase is assembled into colloid particles directly onto the emulsion drop surface, i.e. molecular adsorption leads to effective Pickering stabilisation. The ?-CD stabilised tetradecane-in-water emulsions were so stable that we used this system as a template for preparation of cyclodextrinosomes. These structures were produced solely through formation of cyclodextrin-oil inclusion complexes and their assembly into a crystalline phase on the drop surface retained its stability after the removal of the core oil. The structures of CD-stabilised tetradecane-in-water emulsions were characterised using optical microscopy, fluorescence microscopy, cross-polarised light microscopy and WETSEM while the cyclodextrinosomes were characterised by SEM. We also report the preparation of CD-stabilised emulsions with a range of other oils, including tricaprylin, silicone oil, isopropyl myristate and sunflower oil. We studied the effect of the salt concentration in the aqueous phase, the type of CD and the oil volume fraction on the type of emulsion formed. The CD-stabilised emulsions can be applied in a range of surfactant-free formulations with possible applications in cosmetics, home and personal care. Cyclodextrinosomes could find applications in pharmaceutical formulations as microencapsulation and drug delivery vehicles. PMID:24043288

Mathapa, Baghali G; Paunov, Vesselin N

2013-10-01

158

Low Interfacial Tension Behavior Between Organic Alkali\\/Surfactant\\/Polymer System and Crude Oil  

Microsoft Academic Search

Oil recovery has a great relationship with the interfacial tension (IFT) between displacing fluid and crude oil when using alkali\\/surfactant\\/polymer (ASP) aqueous solution to displace oil in reservoir. Alkali such as sodium hydroxide and sodium carbonate are often used to enhance the applied performances of surfactant and polymer. In this paper, two kinds of organic alkali, triethylamine (TEA) and monoethanolamine

Xiutai Zhao; Yingrui Bai; Zengbao Wang; Xiaosen Shang; Guangmin Qiu; Lifeng Chen

2012-01-01

159

Predictive synthesis of ordered mesoporous silica with maltoside and cationic surfactants based on aqueous lyotropic phase behavior.  

PubMed

Self-assembled nonionic alkyl glycoside surfactants are of interest for creating functional adsorption and catalytic sites at the surface of mesoporous sol-gel-derived materials, but they typically impart poor long-range order when they are used as pore templates. Improved order and control over the functional site density can be achieved by mixing the alkyl polyglycoside surfactant with a cationic surfactant. Here, we investigate the rarely reported lyotropic liquid crystalline (LLC) phase behavior of aqueous solutions of a nonionic disaccharide surfactant, n-dodecyl-beta-d-maltoside (C(12)G(2)/DM), and cetyltrimethylammonium bromide (C(16)TAB) by low-angle powder X-ray diffraction (XRD) and polarized optical microscopy (POM). An approximate ternary phase diagram of the C(16)TAB-C(12)G(2)-water system is developed at 50 degrees C, which includes 2-D hexagonal (P6mm symmetry), bicontinuous cubic (Ia3 d symmetry), lamellar, and rectangular (cmm symmetry) LLC phases. By replacing the volume of water in the phase diagram with an equivalent volume of silica, ordered mesoporous materials are prepared by a nanocasting technique with variable C(12)G(2)/C(16)TAB ratios. For large regions of the phase diagram, this approach is predictive. However, silica materials synthesized with comparatively high C(12)G(2)/C(16)TAB ratios are only poorly ordered in a way that does not correspond to their lyotropic liquid crystalline phase behavior. Also, in contrast with our previous study of mixed C(16)TAB/n-octyl-b-d-glucopyranoside templating [37] the boundary between hexagonal and bicontinuous cubic materials is shifted towards higher surfactant content than in the aqueous LLC system. PMID:19900681

Rahman, Mohammed Shahidur; Rankin, Stephen E

2009-10-17

160

Effect of salts on the phase behavior and the stability of nanoemulsions with rapeseed oil and an extended surfactant.  

PubMed

For many decades, the solubilization of long-chain triglycerides in water has been a challenge. A new class of amphiphiles has been created to overcome this solubilization problem. The so-called "extended" surfactants contain a hydrophilic-lipophilic linker to reduce the contrast between the surfactant-water and surfactant-oil interfaces. In the present contribution, the effects of different anions and cations on the phase behavior of a mixture containing an extended surfactant (X-AES), a hydrotrope (sodium xylene sulfonate, SXS), water, and rapeseed oil were determined as a function of temperature. Nanoemulsions were obtained and characterized by conductivity measurements, light scattering, and optical microscopy. All salting-out salts show a transition from a clear region (O/W nanoemulsion), to a lamellar liquid crystalline phase region, a clear phase (bicontinuous L(3)), and again to a lamellar liquid crystalline phase region with increasing temperature. For the phase diagrams with NaSCN and Na(2)SO(4), only one clear region (O/W nanoemulsion) was observed, which turns into a lamellar phase region at elevated temperatures. Furthermore, the stability of the nanoemulsions was investigated by time-dependent measurements: the visual observation of phase separation, droplet size by dynamic light scattering (DLS), and optical microscopy. The mechanism of the different phase transitions is also discussed. PMID:22537241

Klaus, Angelika; Tiddy, Gordon J T; Solans, Conxita; Harrar, Agnes; Touraud, Didier; Kunz, Werner

2012-05-24

161

On the transport of emulsions in porous media  

SciTech Connect

Emulsions appear in many subsurface applications includingbioremediation, surfactant-enhanced remediation, and enhancedoil-recovery. Modeling emulsion transport in porous media is particularlychallenging because the rheological and physical properties of emulsionsare different from averages of the components. Current modelingapproaches are based on filtration theories, which are not suited toadequately address the pore-scale permeability fluctuations and reductionof absolute permeability that are often encountered during emulsiontransport. In this communication, we introduce a continuous time randomwalk based alternative approach that captures these unique features ofemulsion transport. Calculations based on the proposed approach resultedin excellent match with experimental observations of emulsionbreakthrough from the literature. Specifically, the new approach explainsthe slow late-time tailing behavior that could not be fitted using thestandard approach. The theory presented in this paper also provides animportant stepping stone toward a generalizedself-consistent modeling ofmultiphase flow.

Cortis, Andrea; Ghezzehei, Teamrat A.

2007-06-27

162

RHEOLOGY, PARTICLE SIZE DISTRIBUTION, AND ASPHALTENE DEPOSITION OF VISCOUS ASPHALTIC CRUDE OIL-IN-WATER EMULSIONS FOR PIPELINE TRANSPORTATION  

Microsoft Academic Search

The rheology of an asphaltic heavy crude oil-in-water emulsions stabilized by an anionic (RN) and a nonionic (TEP) surfactants individually or in a mixture has been studied. The investigated crude oil has a non-Newtonian, time dependent, shear thickening, rheopectic behavior with a relatively high yield stress. The relatively high yield stress of this crude oil is attributed to the presence

Nael Zaki; Thorsten Butz; Dagobert Kessel

2001-01-01

163

Comparison of solid particles, globular proteins and surfactants as emulsifiers.  

PubMed

The aim of this paper is to present a short overview of the main mechanisms operative in the formation and stabilization of emulsions by solid particles and, on this basis, to make comparisons between solid particles, surfactants and globular proteins as emulsifiers. When available, simple quantitative relations are presented, with the respective numerical estimates and discussion of the applicability of these relations to particle-stabilized systems. Non-obvious similarities between the different types of emulsifiers are outlined in several cases in which the description of the system can be performed at a phenomenological level. Examples are presented for the process of emulsification, where we show that several simple theoretical expressions, derived originally in the studies of surfactants and protein emulsifiers, can be successfully applied to particle-stabilized emulsions. In contrast, for the phenomena in which the detailed mechanisms of particle adsorption and film stabilization are important, the differences between the various emulsifiers prevail, thus making it impossible to use the same theoretical description. The most important specific characteristics of the solid particles which strongly affect their behavior are the high barrier to particle adsorption, high desorption energy and strong capillary forces between particles trapped in liquid films, which all originate in the relatively large particle size (as compared to the size of surfactant and protein molecules). The capillary mechanism of stabilization of liquid films by solid particles is reviewed in some detail, to emphasize its specific features and to demonstrate the applicability of several simple expressions for approximate estimates. Interestingly, we found that the hypothesis for some exceptionally high coalescence stability of the particle-stabilized emulsions is not supported by the experimental data available in literature. On the other hand, the particles are able to completely arrest the process of Ostwald ripening in foams and emulsions, and this effect can be easily explained with the high desorption energy of the particles and the resulting capillary effects. PMID:18338062

Tcholakova, S; Denkov, N D; Lips, A

2008-02-04

164

Release behavior and stability of encapsulated D-limonene from emulsion-based edible films.  

PubMed

Edible films may act as carriers of active molecules, such as flavors. This possibility confers to them the status of active packaging. Two different film-forming biopolymers, gluten and ?-carrageenans, have been compared. D-Limonene was added to the two film formulations, and its release kinetics from emulsion-based edible films was assessed with HS-SPME. Results obtained for edible films were compared with D-limonene released from the fatty matrix called Grindsted Barrier System 2000 (GBS). Comparing ?-carrageenans with gluten-emulsified film, the latter showed more interesting encapsulating properties: in fact, D-limonene was retained by gluten film during the process needed for film preparation, and it was released gradually during analysis time. D-Limonene did not show great affinity to ?-carrageenans film, maybe due to high aroma compound hydrophobicity. Carvone release from the three different matrices was also measured to verify the effect of oxygen barrier performances of edible films to prevent D-limonene oxidation. Further investigations were carried out by FT-IR and liquid permeability measurements. Gluten film seemed to better protect D-limonene from oxidation. Gluten-based edible films represent an interesting opportunity as active packaging: they could retain and release aroma compounds gradually, showing different mechanical and nutritional properties from those of lipid-based ingredients. PMID:23163743

Marcuzzo, Eva; Debeaufort, Frédéric; Sensidoni, Alessandro; Tat, Lara; Beney, Laurent; Hambleton, Alicia; Peressini, Donatella; Voilley, Andrée

2012-12-04

165

Shear-Induced Deformation of Surfactant Multilamellar Vesicles  

NASA Astrophysics Data System (ADS)

Surfactant multilamellar vesicles (SMLVs) play a key role in the formulation of many industrial products, such as detergents, foodstuff, and cosmetics. In this Letter, we present the first quantitative investigation of the flow behavior of single SMLVs in a shearing parallel plate apparatus. We found that SMLVs are deformed and oriented by the action of shear flow while keeping constant volume and exhibit complex dynamic modes (i.e., tumbling, breathing, and tank treading). This behavior can be explained in terms of an excess area (as compared to a sphere of the same volume) and of microstructural defects, which were observed by 3D shape reconstruction through confocal microscopy. Furthermore, the deformation and orientation of SMLVs scale with radius R in analogy with emulsion droplets and elastic capsules (instead of R3, such as in unilamellar vesicles). A possible application of the physical insight provided by this Letter is in the rationale design of processing methods of surfactant-based systems.

Pommella, Angelo; Caserta, Sergio; Guida, Vincenzo; Guido, Stefano

2012-03-01

166

Rheology and stability of water-in-oil-in-water multiple emulsions containing Span 83 and Tween 80  

Microsoft Academic Search

Multiple emulsions are often stabilized using a combination of hydrophilic and hydrophobic surfactants. The ratio of these\\u000a surfactants is important in achieving stable multiple emulsions. The objective of this study was to evaluate the long-term\\u000a stability of water-in-oil-in-water (W\\/O\\/W) multiple emulsions with respect to the concentrations of Span 83 and Tween 80.\\u000a In addition, the effect of surfactant and electrolyte

Jim Jiao; Diane J. Burgess

2003-01-01

167

Water-in-carbon dioxide emulsions: Formation and stability  

SciTech Connect

Stable water-in-carbon dioxide (W/C) emulsions, for either liquid or supercritical CO{sub 2} containing up to 70 vol % water, are formed with various molecular weight perfluoropolyether ammonium caroxylate surfactants. Water droplet sizes ranging from 3 to 10 {micro}m were determined by optical microscopy. From conductivity measurements, an inversion to C/W emulsions results from a decrease in CO{sub 2} density or salinity at constant pressure, a decrease in surfactant molecular weight, or an increase in temperature. Emulsions become more stable with a change in any of these formulation variables away from the balanced state, which increases interfacial tensions and interfacial tension gradient enhancing Marangoni-Gibbs stabilization. This type of stability is enhanced with an increase in the molecular weight of the surfactant tails, which increases the thickness of the stabilizing films between droplets. W/C emulsions formed with the 7,500 molecular weight surfactant were stable for several days.

Lee, C.T. Jr.; Psathas, P.A.; Johnston, K.P.; Grazia, J. de; Randolph, T.W.

1999-09-28

168

Polymerizable anionic gemini surfactants: physicochemical properties in aqueous solution and polymerization behavior.  

PubMed

A novel polymerizable anionic gemini surfactant has been synthesized and the physicochemical properties in aqueous solution have been studied with a combination of various analytical techniques. The surfactant (PA12-2-12) contains two anionic monomeric parts linked with an ethylene spacer and polymerizable methacryloxy groups covalently bound to the terminal of the hydrocarbon chains. The static surface tension data suggest that, when compared with a conventional (non-polymerizable) anionic gemini surfactant (A12-2-12), (i) the interfacial adsorption of PA12-2-12 occurs more effectively from low surfactant concentrations, whereas (ii) a weak interaction of the polymerizable terminal groups with water molecules (and/or the steric hindrance of the polymerizable groups) plays a significant role in the subsequent molecular packing at the air/aqueous solution interface. The latter effect (as well as the electrostatic repulsion between the anionic headgroups) results in a relatively less packed monolayer film, overcoming the strong intermolecular attractive interaction that is frequently seen for gemini surfactant systems. In the region of low added electrolyte concentrations, PA12-2-12 spontaneously forms spherical micelles in aqueous solution, which is confirmed with the Corrin-Harkins analysis (critical micelle concentration (cmc) vs. total counter-ion concentration) and cryogenic transmission electron microscopy (cryo-TEM). The spherical micelles have been polymerized under UV light irradiation in the absence of added electrolytes. Cryo-TEM measurements confirm that no significant change in the original micelle morphology occurs during the polymerization. This offers a possibility that the polymerizable anionic gemini surfactant should be useful as nano-structural organic templates and/or interfacial stabilizers in aqueous solution. PMID:19584566

Sakai, Kenichi; Wada, Miyuki; Matsuda, Wataru; Tsuchiya, Koji; Takamatsu, Yuichiro; Tsubone, Kazuyuki; Endo, Takeshi; Torigoe, Kanjiro; Sakai, Hideki; Abe, Masahiko

2009-01-01

169

Surfactant mixing rules applied to surfactant enhanced alkaline flooding  

SciTech Connect

This paper discusses surfactant mixing rules which have been used to describe crude oil/alkali/surfactant phase behavior, using David Lloydminster crude oil and the surfactant Neodol 25-3S. It was found that at a fixed salinity and alkali concentration, a specific mole fraction of synthetic surfactant to petroleum soap was required to produce optimal phase behavior as the water-to-oil ratio varied. This methodology is useful in understanding the relationship between the variables of water-to-oil ratio and synthetic surfactant concentration in phase behavior systems that produce a petroleum soap.

Taylor, K.C. (Petroleum Recovery Inst., 3512-33rd St., N.W., Calgary, Alberta T2L 2A6 (CA))

1992-01-01

170

Preparation of charged polystyrene microlatexes by emulsion polymerization induced by gamma rays  

Microsoft Academic Search

Ionic polymerizable surfactants MOBS and MOTB were synthesized and used as emulsifier to synthesize monodisperse polystyrene microlatexes by emulsion polymerization induced by gamma rays. Transmission electron microscopy and X-ray fluorescence were used to characterize the prepared polystyrene. The results show that ionic polymerizable surfactants are effective in the preparation of monodisperse polystyrene microlatexes, and that emulsion polymerization induced by gamma

Xinbo Wang; Zhicheng Zhang; Jun Chen; Shijie Wang

2007-01-01

171

Optimization of Surfactant Mixtures and Their Interfacial Behavior for Advanced Oil Recovery  

SciTech Connect

The objective of this project was to develop a knowledge base that is helpful for the design of improved processes for mobilizing and producing oil left untapped using conventional techniques. The main goal was to develop and evaluate mixtures of new or modified surfactants for improved oil recovery. In this regard, interfacial properties of novel biodegradable n-alkyl pyrrolidones and sugar-based surfactants have been studied systematically. Emphasis was on designing cost-effective processes compatible with existing conditions and operations in addition to ensuring minimal reagent loss.

Somasundaran, Prof. P.

2002-03-04

172

DSC and synchrotron-radiation X-ray diffraction studies on crystallization and polymorphic behavior of palm stearin in bulk and oil-in-water emulsion states  

Microsoft Academic Search

The crystallization and polymorphic behavior of palm stearin (PS) in a bulk state and in oil-in-water (O\\/W) emulsion droplets\\u000a (average diameter, 1.70.3 ?m) was observed by using DSC, optical microscopy, and in situ X-ray diffraction with synchrotron radiation (SR-XRD). For the bulk sample the DSC measurements revealed three main exothermic\\u000a peaks at approximately 31 (large), 21 (small) and 3C (medium)

T. Sonoda; Y. Takata; S. Ueno; K. Sato

2004-01-01

173

Microstructural behavior of water-in-oil emulsions stabilized by fatty acid esters of propylene glycol and zinc fatty acid salts  

Microsoft Academic Search

This manuscript reports an experimental work to observe the microscopic structures and dispersion phase behavior of mixtures of water and oil with combined use of acylpropyleneglycols, containing C16\\/C18 fatty acid moiety, and zinc fatty acid carboxylates (ZnC), both of which play emulsifying roles in the water-in-oil (W\\/O) emulsion systems obtained. Attention was mostly paid to the effects of in situ

Adam Macierzanka; Halina Szel?g

2006-01-01

174

Phase behavior of systems of the type H/sub 2/O-oil-nonionic surfactant-electrolyte  

SciTech Connect

This work shows that the study of simple systems can lead to an understanding of the phase behavior of the pseudoquaternary systems relevant in tertiary oil recovery. A rather simple method has been presented for predicting whether or not a system will show a 3-phase triangle, and how this triangle emerges from the change of the phase diagram with temperature. it was found that the application of such simple surfactants as C4E1 and C4E2 leads to essentially the same phase behavior as that of typical detergents used by other authors. The application of typical commercial detergents leads to more complicated phase diagrams, since the anisotropic phases of such detergents appear to extend deep into the ternary system and may thus lead to an anisotropic structure of the middle phase. This is an additional complication and, in studying the phase behavior of ternary and quaternary systems and the properties of their phases, these complications can be avoided by the application of rather simple surfactants.

Kahlweit, M.

1982-11-01

175

Mixed surfactant systems for enhanced oil recovery  

SciTech Connect

The results of an evaluation of mixed surfactant systems for enhanced oil recovery are described. Several surfactant combinations have been studied. These include alkyl aryl sulfonates as primary surfactants and carboxymethylated ethoxylated (CME) surfactants and ethoxylated sulfonates (ES) as secondary surfactants. The ethoxylated surfactants increase the salinity tolerance of the primary surfactants and, in theory, allow tailoring of the surfactant system to match selected reservoir conditions. The experiments conducted included interfacial tension (IFT) measurements, phase behavior measurements, adsorption and/or chromatographic separation of mixed surfactant systems, measurements of solution properties such as the critical micelle concentration (CMC) of surfactant mixtures, and crude oil displacement experiments. The effects of temperature, surfactant concentration, salinity, presence of divalent ions, hydrocarbon type, and component proportions in the mixed surfactant combinations, and injection strategies on the performance potential of the targeted surfactant/hydrocarbon systems were studied. 40 refs., 37 figs., 8 tabs.

Llave, F.M.; Gall, B.L.; Noll, L.A.

1990-12-01

176

BEHAVIOR OF ANIONIC SURFACTANT MICELLES IN THE PRESENCE OF Al AND Ca  

Microsoft Academic Search

The estimation of the C-potential of ionic surfactant micelles may be useful for the study of adsorption of solutes onto the micellar surface, which causes a reduction of the net electrostatic charge. This work presents results on the variation of ?-potential of alkylsulfate and fatty carboxylate micelles with the bulk concentrations of Al and Ca cations. Combined with results from

Federico I. Talens-Alesson

1999-01-01

177

Adsorption behaviors of cationic surfactants and wettability in polytetrafluoroethylene-solution-air systems.  

PubMed

Measurements of the advancing contact angle (?) and adsorption properties were carried out for aqueous solutions of four cationic surfactants, hexadecanol glycidyl ether ammonium chloride (C(16)PC), Guerbet alcohol hexadecyl glycidyl ether ammonium chloride (C(16)GPC), hexadecanol polyoxyethylene(3) glycidyl ether ammonium chloride(C(16)(EO)(3)PC), and Guerbet alcohol hexadecyl polyoxyethylene(3) glycidyl ether ammonium chloride (C(16)G(EO)(3)PC), on the polytetrafluoroethylene (PTFE) surface using the sessile drop analysis. The obtained results indicate that the contact angle decreases to a minimum with the increasing concentration for all cationic surfactants. Surfactants with branched chain show lower ? values. Moreover, an increase of adhensional tension on the PTFE-water interface has been observed for the four cationic surfactants, and the branched ones have larger increases of adhensional tension. It is very interesting that the sharp decrease of ? appears mainly after critical micelle concentration (cmc) for C(16)GPC, C(16)(EO)(3)PC, and C(16)G(EO)(3)PC, which is quite different from traditional cationic surfactants reported in the literature. Especially for C(16)G(EO)(3)PC, there are two saturated adsorption stages on PTFE surface after cmc (which means the saturated adsorption film at air-solution interface has been formed). In the first saturated stage, the C(16)G(EO)(3)PC molecules are oriented parallel to the PTFE surface with saturated monolayer formed through hydrophobic interaction and hydrogen bond. In the second saturated stage, the hemimicelle has been formed on the PTFE surface, which can be supported by the QCM-D and SPR measurements. PMID:23148857

Liu, Dan-Dan; Xu, Zhi-Cheng; Zhang, Lei; Luo, Lan; Zhang, Lu; Wei, Tian-Xin; Zhao, Sui

2012-11-26

178

Particle settling in oil-in-water emulsions  

Microsoft Academic Search

The sedimentation velocity of precision steel spheres in several oil-in-water emulsions stabilized by a range of commercially available surfactants has been measured. In particular, the interaction between the size distribution of oil droplets, the viscosity of emulsions and the terminal velocity of spheres has been investigated in the Reynolds number range ?10 to ?1000. When the oil droplets are much

D. Beydoun; D. Guang; R. P. Chhabra; J. A. Raper

1998-01-01

179

FLOW PROPERTIES OF WEATHERED CRUDE OILS AND THEIR EMULSIONS  

Microsoft Academic Search

The present paper proposes the emulsification of weathered crude oils in water as a competitive and cost effective method for reducing their viscosities. Weathered crude oil samples were collected from major Kuwaiti oil lakes. Emulsion preparation involved using, either a nonionic surfactant or alkali, as well as both alkali and fatty acid. The obtained emulsions were characterized by measuring the

Ahmed A. Elgibaly; Ibrahim S. Nashawi; Mahmoud A. Tantawy; Ali Elkamel

1999-01-01

180

DEMULSIFICATION OF WATER IN OIL EMULSIONS USING WATER SOLUBLE DEMULSIFIERS  

Microsoft Academic Search

The possibility of using a water soluble,as opposed to the conventional oil soluble demulsifier, to destabilize a w\\/o emulsion in crude oil has been explored. It was found experimentally that a surfactant soluble in the water (dispersed) phase could destabilize the emulsion. Polymer molecules with varying HLB's and molecular weights and structure were synthesized and these compounds were added to

C. S. Shetty; A. D. Nikolov; D. T. Wasan; B. R. Bhattacharyya

1992-01-01

181

Well treatment with emulsion dispersions  

SciTech Connect

In a method of treating a subterranean formation, a well treatment composition comprising a dispersion of a water-in-oil emulsion in an aqueous medium is injected into the formation. The water-in-oil emulsion has an internal aqueous phase and an external phase containing a liquid hydrocarbon and a surfactant soluble in the hydrocarbon. The compositions can be designed to perform various well treatment applications including hydraulic fracturing and acidizing and can also be used to encapsulate or to transport well treatment materials and chemicals into the wellbore or formation. Treatment methods may also employ dispersions of a reactive simple or multiple emulsion. The distinct phases of the compositions may be selected to form treatment solutions upon mixing. Thus, improved acidizing may be achieved through an in situ reaction format.

Cooke, C.E.; Li, N.N.; Muecke, T.W.; Salathiel, W.M.

1982-11-16

182

Phase behavior and rheological properties of a salt-free catanionic surfactant TTAOH/LA/H2O system.  

PubMed

Conventional cationic and anionic (catanionic) surfactant mixtures tend to form precipitates at the mixing molar ratio of the cationic and anionic surfactant of 1:1 because of the excess salt formed by their counterions. By using OH- and H+ as the counterions, however, excess salt can be eliminated, and salt-free catanionic systems can be obtained. Here, we report the detailed phase behavior and rheological properties of salt-free catanionic surfactant system of tetradecyltrimethylammonium hydroxide (TTAOH)/lauric acid (LA)/H2O. With the variation of mixing molar ratio of LA to TTAOH (rho=nLA/nTTAOH), the system exhibits much richer phase behavior induced by growth and transition of aggregates. Correspondingly, the rheological property of the system changes significantly. Take the series of samples with fixed total surfactant concentration (cT) to be 15 mg.mL(-1), the system only forms a low viscous L 1 phase with a Newton fluid character at the TTAOH-rich side. With increasing rho, first a shear-thickening L1 phase region is observed at 0.70or=1.05, and finally, at rho>or=1.13, the excess LA will separate from the bulk solution and form a white top layer. Investigations were also carried out by varying c T at fixed rho and by changing temperature, respectively. It was found micelle growth would be greatly suppressed at higher temperatures. However, the vesicle phases showed a considerable resistance against temperature rise. PMID:18671361

Li, Hongguang; Hao, Jingcheng

2008-07-31

183

Fine silica powder modified with quaternary ammonium group 3. The adsorption behavior of anionic surfactants  

Microsoft Academic Search

The adsorption, zeta potential, and mean particle size of fine silica powder modified with quaternary ammonium groups having alkyl chains of various lenghts (?N+(CmH2m + 1)(CH3)2, XNm, m = 4, 6, 8, 10, 12, 14, 16, and 18) were measured as a function of the concentration of the anionic surfactant (sodium dodecyl sulfate or sodium tetradecyl sulfate) in the suspensions.

Tsuneo Suhara; Hiroshi Fukui; Michihiro Yamaguchi; Fukuji Suzuki

1996-01-01

184

Behavior of Oil Droplets on an Electrified Solid Metal Surface Immersed in Ionic Surfactant Solutions  

Microsoft Academic Search

The present study investigates the change in the shape of oil droplets immersed in an ionic surfactant solution when the droplets are in contact with metal surfaces to which an electrical potential is applied. The three-phase system of aqueous solution?oil?steel was subjected to low-voltage electric potentials, which resulted in sometimes dramatic changes in droplet shape and wetting. This electric potential

David J. Keffer; S. A. Morton; R. M. Counce; D. W. DePaoli

2005-01-01

185

Adsorption layer structures and spreading behavior of aqueous non-ionic surfactants on graphite  

Microsoft Academic Search

The adsorbed self-assembly structures of a series of trisiloxane M(D?En)M, n=6, 8, and 12 and Tris (ethylene oxide) dodecyl ether C12E3 non-ionic surfactants on graphite have been studied by AFM using tapping mode for imaging and contact mode for force measurements. In the concentration range of 2–5 times of the CMC, C12E3 aggregates are arranged in parallel stripes, oriented along

T Svitova; R. M Hill; C. J Radke

2001-01-01

186

Phase behavior, rheological property, and transmutation of vesicles in fluorocarbon and hydrocarbon surfactant mixtures.  

PubMed

We present a detailed study of a salt-free cationic/anionic (catanionic) surfactant system where a strongly alkaline cationic surfactant (tetradecyltrimethylammonium hydroxide, TTAOH) was mixed with a single-chain fluorocarbon acid (nonadecafluorodecanoic acid, NFDA) and a hyperbranched hydrocarbon acid [di-(2-ethylhexyl)phosphoric acid, DEHPA] in water. Typically the concentration of TTAOH is fixed while the total concentration and mixing molar ratio of NFDA and DEHPA is varied. In the absence of DEHPA and at a TTAOH concentration of 80 mmol·L(-1), an isotropic L(1) phase, an L(1)/L(?) two-phase region, and a single L(?) phase were observed successively with increasing mixing molar ratio of NFDA to TTAOH (n(NFDA)/n(TTAOH)). In the NFDA-rich region (n(NFDA)/n(TTAOH) > 1), a small amount of excess NFDA can be solubilized into the L(?) phase while a large excess of NFDA eventually leads to phase separation. When NFDA is replaced gradually by DEHPA, the mixed system of TTAOH/NFDA/DEHPA/H(2)O follows the same phase sequence as that of the TTAOH/NFDA/H(2)O system and the phase boundaries remain almost unchanged. However, the viscoelasticity of the samples in the single L(?) phase region becomes higher at the same total surfactant concentration as characterized by rheological measurements. Cryo-transmission electron microscopic (cryo-TEM) observations revealed a microstructural evolution from unilamellar vesicles to multilamellar ones and finally to gaint onions. The size of the vesicle and number of lamella can be controlled by adjusting the molar ratio of NFDA to DEHPA. The dynamic properties of the vesicular solutions have also been investigated. It is found that the yield stress and the storage modulus are time-dependent after a static mixing process between the two different types of vesicle solutions, indicating the occurrence of a dynamic fusion between the two types of vesicles. The microenvironmental changes induced by aggregate transitions were probed by (19)F NMR as well as (31)P NMR measurements. Upon replacement of NFDA by DEHPA, the signal from the (19)F atoms adjacent to the hydrophilic headgroup disappears and that from the (19)F atoms on the main chain becomes sharper. This could be interpreted as an increase of microfluidity in the mixed vesicle bilayers at higher content of DEHPA, whose alkyl chains are expected to have a lower chain melting point. Our results provide basic knowledge on vesicle formation and their structural evolution in salt-free catanionic surfactant systems containing mixed ion pairs, which may contribute to a deeper understanding of the rules governing the formation and properties of surfactant self-assembly. PMID:22646993

Yuan, Zaiwu; Qin, Menghua; Chen, Xiushan; Liu, Changcheng; Li, Hongguang; Hao, Jingcheng

2012-06-11

187

Fluorocarbon emulsions--the stability issue.  

PubMed

Long-term room temperature stability of ready-to-use concentrated fluorocarbon emulsions is necessary in order to fully exploit the therapeutic potential of fluorocarbons. Consequently, considerable efforts have been directed at investigating the physical nature of such emulsions, the mechanisms which lead to their degradation and the means of counteracting these. The particles which constitute typical fluorocarbon/egg yolk phospholipid emulsions have been identified to be surfactant-coated fluorocarbon droplets and lipid vesicles. Better understanding has been gained on the formation, structure and evolution of these particles during processing and storage. This has led to optimized formulations and processing, better control of emulsion characteristics and significantly improved stability. Molecular diffusion (Ostwald ripening or transcondensation) has been shown to be the maun mechanism of degradation when particles are less than 1 micron in diameter, even for the highly concentrated (volume fraction of fluorocarbon up to 50%) second generation fluorocarbon emulsions. Significant emulsion stabilization has been accomplished by adding fluorochemicals which are both less volatile and less water soluble, and nevertheless have an organ dwell time acceptable for intravascular use. The rate of molecular diffusion can also be reduced by decreasing the fluorocarbon/water interfacial tension; this was effectively achieved with appropriate, well-defined fluorinated surfactants. A further, novel means of stabilizing fluorocarbon-in-water emulsions makes use of mixed fluorocarbon-hydrocarbon amphiphiles which act as molecular dowels to reinforce the adhesion between the fluorocarbon phase and the lipophilic zone of the surfactant film. Both long-term room temperature stability, and particle-size control over a large range of diameter, have been achieved by applying this principle. All in all it can be said that the challenge of producing injectable fluorocarbon emulsions with long-term room temperature particle size stability has been met. PMID:7849970

Postel, M; Riess, J G; Weers, J G

1994-01-01

188

Role of liquid crystal in the emulsification of a gel emulsion with high internal phase fraction.  

PubMed

A gel emulsion with high internal oil phase volume fraction was formed via an inversion process induced by a water-oil ratio change. The process involved the formation of intermediate multiple emulsions prior to inversion. The multiple emulsions contain a liquid crystal formed by the surfactant with water; this was both predicted by the equilibrium phase diagram as well as observed using polarization microscopy. These multiple emulsions were more stable compared to alternative multiple emulsions prepared in the same way with a surfactant that does not form liquid crystals. While the formation of a stable intermediate multiple emulsion may not be a necessary condition for the inversion to occur, the transitional presence of a liquid crystal proved to be a significant factor in the stabilization of the intermediate multiple emulsions. The resulting gel emulsion contained a small fraction of the liquid crystal according to the phase diagram, and it exhibited excellent stability. PMID:19781712

Liu, Yihan; Friberg, Stig E

2009-09-03

189

Influence of droplet charge on the chemical stability of citral in oil-in-water emulsions.  

PubMed

The chemical stability of citral, a flavor component widely used in beverage, food, and fragrance products, in oil-in-water emulsions stabilized by surfactants with different charge characteristics was investigated. Emulsions were prepared using cationic (lauryl alginate, LAE), non-ionic (polyoxyethylene (23) lauryl ether, Brij 35), and anionic (sodium dodecyl sulfate, SDS) surfactants at pH 3.5. The citral concentration decreased over time in all the emulsions, but the rate of decrease depended on surfactant type. After 7 d storage, the citral concentrations remaining in the emulsions were around 60% for LAE- or Brij 35-stabilized emulsions and 10% for SDS-stabilized emulsions. An increase in the local proton (H(+)) concentration around negatively charged droplet surfaces may account for the more rapid citral degradation observed in SDS-stabilized emulsions. A strong metal ion chelator (EDTA), which has previously been shown to be effective at increasing the oxidative stability of labile components, had no effect on citral stability in LAE- or Brij 35-stabilized emulsions, but it slightly decreased the initial rate of citral degradation in SDS-stabilized emulsions. These results suggest the surfactant type used to prepare emulsions should be controlled to improve the chemical stability of citral in emulsion systems. PMID:20722908

Choi, Seung Jun; Decker, Eric Andrew; Henson, Lulu; Popplewell, L Michael; McClements, David Julian

2010-08-01

190

Interfacial rheological properties of adsorbed protein layers and surfactants: a review  

Microsoft Academic Search

Proteins and low molecular weight (LMW) surfactants are widely used for the physical stabilisation of many emulsions and foam based food products. The formation and stabilisation of these emulsions and foams depend strongly on the interfacial properties of the proteins and the LMW surfactants. Therefore these properties have been studied extensively. In this review an overview is given of interfacial

Martin A. Bos; Ton van Vliet

2001-01-01

191

Fading phenomena of azo oil dye in anionic-nonionic surfactant solutions III. The effect of solubilizates on the fading behavior of azo oil dye in mixed surfactant systems  

Microsoft Academic Search

The effects of solubilizates on the fading behavior of 4-phenylazo-1-naphthol (4-OH) in aqueous solutions of anionic-nonionic mixed surfactant systems are described; the systems studied are sodium dodecyl sulfate (SDS) — octadecyl poly(oxyethylene) ethers (C18POE20). The fading rate of 4-OH in the mixed solution was independent of the addition of octane. By adding octanoic acid, the rate became faster. On the

H. Uchiyamal; M. Abel; K. Ogino

1987-01-01

192

Optimization of Surfactant Mixtures and Their Interfacial Behavior for Advanced Oil Recovery  

SciTech Connect

The goal of this report is to develop improved extraction processes to mobilize and produce the oil left untapped using conventional techniques. Current chemical schemes for recovering the residual oil have been in general less than satisfactory. High cost of the processes as well as significant loss of chemicals by adsorption on reservoir materials and precipitation has limited the utility of chemical-flooding operations. There is a need to develop cost-effective, improved reagent schemes to increase recovery from domestic oil reservoirs. The goal of the report was to develop and evaluate novel mixtures of surfactants for improved oil recovery.

Somasundaran, Prof. P.

2001-02-27

193

Transient behavior of simultaneous flow of gas and surfactant solution in consolidated porous media  

SciTech Connect

The main objective of this experimental research was to investigate the mechanisms of foam generation and propagation in porous media. Results obtained give an insight into the conditions of foam generation and propagation in porous media. The rate of propagation of foam is determined by the rates of lamellae generation, destruction, and trapping. Several of the factors that contribute to foam generation have studied with Chevron Chaser SD1000 surfactant. Interfacial tension (IFT) measurements were performed using a spinning drop apparatus. The IFT of two surfactant samples of different concentrations were measured with dodecane and crude oil from the Huntington Beach Field as a function of temperature and time. Foam was used as an oil-displacing fluid. However, when displacing oil, foam was not any more effective than simultaneous brine and gas injection. A series of experiments was performed to study the conditions of foam generation in Berea sandstone cores. Results show that foam may be generated in sandstone at low flow velocities after extended incubation periods. The effect of pregenerating foam before injection into the sandstone was also studied. The pressure profiles in the core were monitored using three pressure taps along the length of the core. A systematic study of foaming with different fluid velocities and foam qualities provides extensive data for foam flow conditions. 134 refs., 57 figs., 2 tabs.

Baghdikian, S.Y.; Handy, L.L.

1991-07-01

194

Evaluation of rheological properties and interfacial tension of polymer-surfactant mixtures  

Microsoft Academic Search

The application of the polymer in emulsion can promote a larger stability, due to the presence of a surfactant, which has the capacity to modify the interfacial tension and to form a film between the phases of the emulsion 5, 7 . Thereby, the injection of a polymer emulsion can promote an increase of oil recovery. The purpose of this

A. C. M. Valentim; R. B. Garcia

195

Characterization of dispersed three-phase systems with applications to solids-stabilized emulsions  

SciTech Connect

The factor affecting the formation and stability of emulsions stabilized by finely solid particles were investigated. For the water-in-oil emulsions that were studied, the three-phase contact angle, the ratio of water drop diameter to particle diameter (size ratio) and the interaction between particles at the oil-water interface were found to be important. A free energy analysis was conducted on the process of particle transfer from an oil to a water drop. The transfer became more favorable as the size ratio increased and as the solids became more hydrophilic. A model was suggested to explain the phenomenon of oil loss associated with the separation of solids-stabilized emulsions. The oil loss was found to increase with the size ratio and was not very strongly dependent on the contact angle. The demulsification of water-in-shale oil emulsions was also optimized with respect to demulsifier concentration, speed of agitation and temperature. The adsorption behavior of shale asphaltenes and maltenes on sodium montmorillonite and its influence on particle wettability were studied to ascertain the contribution of contact angle to emulsion stability. Process modifications through the use of pH control, surfactant and other additives were devised. A new technique was developed to measure the film tension between a coalescing water drop and a planar oil-water interface covered with particles. The interaction energy of the particles at the interface was also estimated. The effect of interfacial particle packing density, pH, surfactant and demulsifier on the film tension and particle interaction energy were assessed.

Menon, V.B.

1986-01-01

196

The dynamic behavior of an insoluble surfactant monolayer spreading on a thin liquid film  

NASA Astrophysics Data System (ADS)

The spreading of surface active material on thin liquid films is studied by investigating the dynamics of a finite reservoir of insoluble surfactant spreading on a thin layer of Newtonian liquid. The first part of this thesis examines the unperturbed spreading process. It is shown that Marangoni dominated spreading leads to large deformations in the underlying liquid layer which diminish when the relative contribution of surface diffusion, capillary and gravitational forces is increased. A comparison between experimental measurements of the film deformation obtained by Moiré topography with theoretical predictions, performed for the first time, reveals excellent agreement. This study also shows that the mass of surfactant that participates in the spreading is a miniscule fraction of the total mass deposited. Simulations of surfactant delivery in model pulmonary airways demonstrate the adverse effect of a non-uniform field of pre-existing contaminants on the spreading and the importance of its inclusion in determining an optimal set of conditions for rapid and efficacious spreading. The second part describes efforts aimed at identifying the physical mechanisms responsible for some unusual fingered spreading patterns observed experimentally. A linear stability analysis of self-similar solutions governing Marangoni dominated spreading in rectilinear geometry, conducted in the quasi-steady-state- approximation, predicts stable modes. A similar analysis including effects of surface diffusion and capillarity also yields asymptotically stable flow. A transient growth analysis of the non-normal operators governing the evolution of disturbances yields amplification of initially infinitesimal perturbations by orders of magnitude on time scales comparable to Marangoni shear times. Disturbances of all wavenumbers eventually decay in agreement with the long time analyses. Numerical simulations of the nonlinear governing equations, however, show that, for the parameter values considered, the large amplification is insufficient to drive sustained finger formation and unstable flow in the nonlinear regime. Simulations of mode coupling interactions reveal that coalescence of adjacent fingers leads to an overall shift of the fingering patterns to longer transverse length scales. Preliminary results also indicate that van der Waals forces can enhance the growth of transverse disturbances in the thinning region of the film leading to possible asymptotic growth.

Matar, Omar Kamal

197

An alkyl polyglucoside-mixed emulsifier as stabilizer of emulsion systems: the influence of colloidal structure on emulsions skin hydration potential.  

PubMed

To be considered as a suitable vehicle for drugs/cosmetic actives, an emulsion system should have a number of desirable properties mainly dependent on surfactant used for its stabilization. In the current study, C(12-14) alkyl polyglucoside (APG)-mixed emulsifier of natural origin has been investigated in a series of binary (emulsifier concentration 10-25% (w/w)) and ternary systems with fixed emulsifier content (15% (w/w)) with or without glycerol. To elucidate the systems' colloidal structure the following physicochemical techniques were employed: polarization and transmission electron microscopy, X-ray diffraction (WAXD and SAXD), thermal analysis (DSC and TGA), complex rheological, pH, and conductivity measurements. Additionally, the emulsion vehicles' skin hydration potential was tested in vivo, on human skin under occlusion. In a series of binary systems with fixed emulsifier/water ratios ranging from 10/90 to 25/75 the predominance of a lamellar mesophase was found, changing its character from a liquid crystalline to a gel crystalline type. The same was observed in gel emulsions containing equal amounts of emulsifier and oil (15% (w/w)), but varying in glycerol content (0-25%). Different emulsion samples exhibited different water distribution modes in the structure, reflecting their rheological behavior and also their skin hydration capacity. PMID:21421214

Savic, Snezana; Lukic, Milica; Jaksic, Ivana; Reichl, Stephan; Tamburic, Slobodanka; Müller-Goymann, Christel

2011-02-24

198

The effects of oil, dispersant, and emulsions on the survival and behavior of an estuarine teleost and an intertidal amphipod  

Microsoft Academic Search

Killfish (Fundulus heteroclitus) and amphipods (Gammarus oceanicus) were exposed seperately to either a No. 2 fuel oil, AP dispersant, or emulsions of the two in a static system. Both species exhibited a concentration-dependent response to all three treatments. However, emulsification of oil with dispersant clearly increased its lethal effect on killfish survival, but did not cause a differential change in

R. G. Butler; W. Trivelpiece; D. S. Miller

1982-01-01

199

SURFACTANT-OIL-WATER SYSTEMS NEAR THE AFFINITY INVERSION PART VIII : OPTIMUM FORMULATION AND PHASE BEHAVIOR OF MIXED ANIONIC-NONIONIC SYSTEMS VERSUS TEMPERATURE  

Microsoft Academic Search

Surfactant-oil-water systems with a phase behavior insensitive to temperature and composition can be achieved by anionic-nonionic mixing. By using of a linear mixing rule and a linear temperature dependency, it is possible to interpret most of the features exhibited by the experimental phase behavior data obtained with sulfonate and ethoxylated alkylphenol mixtures. Deviation from the theoretical model are probably due

R. E. Antón; A. Graciaa; J. Lachaise; J. L. Salager

1992-01-01

200

Stability of water/crude oil emulsions based on interfacial dilatational rheology.  

PubMed

The dilatational viscoelasticity behaviors of water/oil interfaces formed with a crude oil and its distilled fractions diluted in cyclohexane were investigated by means of an oscillating drop tensiometer. The rheological study of the w/o interfaces at different frequencies has shown that the stable w/o emulsions systematically correspond to interfaces which present the rheological characteristics of a 2D gel near its gelation point. The stability of emulsions was found to increase with both the gel strength and the glass transition temperature of the gel. As expected, the indigenous natural surfactants responsible for the formation of the interfacial critical gel have been identified as the heaviest amphiphilic components present in the crude oil; i.e., asphaltenes and resins. Nevertheless, we have shown that such a gel can also form in the absence of asphaltene in the oil phase. PMID:16324706

Dicharry, Christophe; Arla, David; Sinquin, Anne; Graciaa, Alain; Bouriat, Patrick

2005-12-01

201

Rapid crystallization and morphological adjustment of zeolite ZSM-5 in nonionic emulsions  

NASA Astrophysics Data System (ADS)

Zeolite ZSM-5 was synthesized for the first time in a nonionic emulsion composed of polyoxyethylated alkylphenol, butanol, cyclohexane and tetraethylammonium hydroxide (TEAOH)-containing zeolite synthesis mixture. The crystallization kinetics in the emulsion was investigated and the ZSM-5 product was characterized in detail by XRD, SEM, FT-IR, TG, N2 adsorption and CHN analysis techniques. Compared with the conventionally hydrothermal synthesis with the same structure directing agent TEAOH, the emulsion system allows rapid crystallization of ZSM-5. The ZSM-5 product exhibits unusual agglomerated structure and possesses larger specific surface area. The FT-IR, TG results plus CHN analysis show the encapsulation of a trace of emulsion components in the emulsion ZSM-5. Control experiments show the emulsion system exerts the crystallization induction and morphological adjustment effects mainly during the aging period. The effects are tentatively attributed to the confined space domains, surfactant-water interaction as well as surfactant-growing crystals interaction existing in the emulsion.

Zhang, Ying; Jin, Chao

2011-01-01

202

Influence of nonionic surfactants on the surface and interfacial film properties of asphaltenes investigated by Langmuir balance and Brewster angle microscopy.  

PubMed

The interfacial film properties of asphaltenes and their mixtures with nonionic surfactants (polyoxyethylene nonylphenols) have been investigated using a Langmuir trough and a Brewster angle microscope (BAM). The effects of asphaltene concentration, surfactant/asphaltene ratio, and surfactant HLB (hydrophilic-lipophilic balance) have been studied at the air-water interface. The BAM image for asphaltenes show irregular domains with various structures even before compression, indicating preaggregation of asphaltenes in the spreading solution. The film morphology depends on both concentration and total amount of asphaltenes in the spreading solution. Lower proportions of surfactant (5 wt %) compared to asphaltenes increases the film compressibility and disperses the asphaltene domains; however, the behavior of the surface film is still dominated by asphaltenes. When the proportion of surfactant is increased to 50 wt %, surfactant molecules can occupy the interface top layer with multilayer formation by asphaltenes beneath this layer, and a relatively homogeneous film is observed by BAM. At the oil-water interface, surfactant was examined as both an inhibitor and a demulsifier for water-in-oil emulsions. Surfactants with intermediate HLB = 14.2 are most efficient in both cases preventing asphaltene adsorption at the interface by competitive adsorption and breaking the existing asphaltene film by displacement of asphaltenes from the interface. PMID:20536160

Fan, Yanru; Simon, Sébastien; Sjöblom, Johan

2010-07-01

203

Morphology and stability of CO2-in-water foams with nonionic hydrocarbon surfactants.  

PubMed

The morphologies, stabilities, and viscosities of high-pressure carbon dioxide-in-water (C/W) foams (emulsions) formed with branched nonionic hydrocarbon surfactants were investigated by in situ optical microscopy and capillary rheology. Over two dozen hydrocarbon surfactants were shown to stabilize C/W foams with Sauter mean bubble diameters as low as 1 to 2 microm. Coalescence of the C/W foam bubbles was rare for bubbles larger than about 0.5 microm over a 60 h time frame, and Ostwald ripening became very slow. By better blocking of the CO(2) and water phases with branched and double-tailed surfactants, the interfacial tension decreases, the surface pressure increases, and the C/W foams become very stable. For branched surfactants with propylene oxide middle groups, the stabilities were markedly lower for air/water foams and decane-water emulsions. The greater stability of the C/W foams to coalescence may be attributed to a smaller capillary pressure, lower drainage rates, and a sufficient surface pressure and thus limiting surface elasticity, plus small film sizes, to hinder spatial and surface density fluctuations that lead to coalescence. Unexpectedly, the foams were stable even when the surfactant favored the CO(2) phase over the water phase, in violation of Bancroft's rule. This unusual behavior is influenced by the low drainage rate, which makes Marangoni stabilization of less consequence and the strong tendency of emerging holes in the lamella to close as a result of surfactant tail flocculation in CO(2). The high distribution coefficient toward CO(2) versus water is of significant practical interest for mobility control in CO(2) sequestration and enhanced oil recovery by foam formation. PMID:20345107

Adkins, Stephanie S; Chen, Xi; Chan, Isabel; Torino, Enza; Nguyen, Quoc P; Sanders, Aaron W; Johnston, Keith P

2010-04-20

204

Cleavable surfactants  

Microsoft Academic Search

A brief review of cleavable surfactants, synthesized and characterized by the author and his co-workers, is presented. Two types of cleavable surfactants have been reported; each contains a labile functional group. Both single and double-chain first generation cleavable surfactants are cleaved to give nonsurfactant fragments: a water-insoluble organic compound and a water-soluble ionic compound. Single-chain second generation cleavable surfactants are

David A. Jaeger

1995-01-01

205

Adsorption behavior of DNA onto a cationic surfactant monolayer at the air-water interface  

NASA Astrophysics Data System (ADS)

This communication reports the adsorption of DNA to the preformed Langmuir monolayer of cationic surfactant Octadecylamine (ODA) at the air-water interface and thereby formation of ODA/DNA complex monolayer at the interface. Effect of concentration of DNA in the subphase as well as subphase pH on the adsorption of DNA onto ODA monolayer assemblies have been studied by monitoring the change in surface pressure of ODA/DNA complex monolayer as a function of time. The complex monolayer was also transferred onto solid substrate to prepare ODA/DNA Langmuir-Blodgett films which were analyzed by UV-vis absorption, ATR-FTIR spectroscopic techniques. The most significant observations is that the extent of interactions between ODA and DNA at the air-water interface increases with increasing concentration of DNA in the subphase and also subphase pH. At higher pH, hydrophobic interaction dominates over electrostatic interaction between DNA and ODA in the aqueous subphase. DNA immobilized in the backbone of ODA lies almost flat or extended onto solid substrate at neutral pH whereas, they lie aggregated and compacted coil rather than flat when adsorbed from high pH namely, 11.5 of the subphase. This was confirmed by atomic force microscopy of these complex LB films onto solid substrate.

Hansda, Chaitali; Hussain, Syed Arshad; Bhattacharjee, Debajyoti; Paul, Pabitra Kr.

2013-11-01

206

Understanding and exploiting the phase behavior of mixtures of oppositely charged polymers and surfactants in water.  

PubMed

Complexes of oppositely charged polymers and surfactants (OCPS) in water come in many varieties, including liquid-crystalline materials, soluble complexes, structured nanoparticles, and water-insoluble surface layers. The range of available structures and properties increases even further with the addition of other amphiphilic substances that may enter, or even dissolve, the complexes, depending on the nature of the additive. Simple operations may change the properties of OCPS systems dramatically. For instance, dilution with water can induce a phase separation in an initially stable OCPS solution. More complicated processes, involving chemical reactions, can be used to either create or disintegrate OCPS particles or surface layers. The richness of their properties has made OCPS mixtures ubiquitous in everyday household products, such as shampoos and laundry detergents, and also attractive ingredients in the design of new types of responsive particles, surfaces, and delivery agents of potential use in future applications. A challenge for the rational design of an OCPS system is, however, to obtain a good fundamental understanding of how to select molecular shapes and sizes and how to tune the hydrophobic and electrostatic interactions such that the desired properties are obtained. Recent studies of OCPS phase equilibria, using a strategy where the minimum number of components is always used to address a particular question, have brought out general rules and trends that can be used for such a rational design. Those fundamental studies are reviewed here, together with more application-oriented studies where fundamental learning has been put to use. PMID:23701384

Piculell, Lennart

2013-06-19

207

CHARACTERISTICS OF SURFACTANTS IN TOXICITY IDENTIFICATION EVALUATIONS  

EPA Science Inventory

The behavior of a number of anionic, nonionic and cationic surfactants in manipulations associated with toxicity identification evaluations was studied. t was found that toxicity of the surfactants could be removed from aqueous samples via aeration, apparently through sublation. ...

208

Study of the surfactant nanostructures at the solid\\/liquid interface  

Microsoft Academic Search

Surfactant adsorption is widely studied because it is related to many technological applications, such as wetting, adhesion, emulsion, foam, separation science, polymer blends and composites and stabilization of colloidal dispersions. ^ Silicone surfactant, one of the most important members in nonionic surfactants family, exhibits superior performance in anti-foaming, corrosion protection, bactericidal, skin, hair, and fabric conditions. A group of trisiloxanes,

Jinping Dong

2003-01-01

209

Design, synthesis and evaluation of fluorocarbons and surfactants for in vivo applications. New perfluoroalkylated polyhydroxylated surfactants.  

PubMed

The progress achieved since the advent of Fluosol-DA is summarized in this paper, with special focus on the synthesis and evaluation of more adequate, reliable, industrially feasible fluorocarbons, structure/property relationships--molecular weight being recognized as the pre-eminent determining factor of both the fluorocarbon's excretion rate and the emulsion's stability-, the preparation of significantly more concentrated, more efficacious emulsions, etc. The key to further progress and better mastery of the emulsions' characteristics, especially in relation to increased shelf-life, prolonged i.v. persistence, and versatility, now lies in the development of new surfactants, better adapted to this objective. New families of well defined, monodisperse perfluoroalkylated polyhydroxylated surfactants derived from sugars and related compounds have been synthesized and fully characterized. Preliminary evaluation of their surface-active properties, emulsion stabilizing capacity and biocompatibility are reported. PMID:3052646

Riess, J G; Arlen, C; Greiner, J; Le Blanc, M; Manfredi, A; Pace, S; Varescon, C; Zarif, L

1988-01-01

210

BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS  

SciTech Connect

The aim of the project is to develop and evaluate efficient novel surfactant mixtures for enhanced oil recovery. Surfactant loss by adsorption or precipitation depends to a great extent on the type of surfactant complexes and aggregates formed. Such information as well as techniques to generate the information is lacking currently particularly for surfactant mixtures and surfactant/polymer systems. A novel analytical centrifuge application is explored during the last period to generate information on structures-performance relationship for different surfactant aggregates in solution and, in turn, at interfaces. To use analytical untracentrifuge for surfactant mixtures, information on partial specific volumes of single surfactants and their mixtures is required. Towards this purpose, surface tension and density measurements were performed to determine critical micellar concentrations (cmc), partial specific volumes of n-dodecyl-{beta}-Dmaltoside (DM), nonyl phenol ethoxylated decyl ether (NP-10) and their 1:1 mixtures at 25 C. Durchschlag's theoretical calculation method was adopted to calculate the partial specific volumes. Effects of temperature and mixing, as well as methods used for estimation on micellization and partial specific volumes were studied during the current period. Surface tension results revealed no interaction between the two surfactants in mixed micelles. Partial specific volume measurements also indicated no interaction in mixed micelles. Maximum adsorption density, area per molecule and free energy of micellization were also calculated. Partial specific volumes were estimated by two experimental methods: d{sub {rho}}/dc and V{sub {sigma}}. The difference between the results of using the two methods is within 0.5% deviation. It was found that the partial specific volume is concentration dependent and sensitive to changes in temperature. The information generated in this study will be used for the study of surfactant aggregate mass distribution in mixed systems. Such information will in future be used to identify optimum surfactant.

Prof. P. Somasundaran

2002-09-30

211

Optimization of water-in-oil nanoemulsions by mixed surfactants  

Microsoft Academic Search

The formation of water-in-oil (W\\/O) nanoemulsions in isohexadecane\\/mixed nonionic surfactant\\/water system has been achieved by a low-energy emulsification. Effects of polyoxyethylene 2-lauryl ether (C12E2) and polyoxyethylene 4-lauryl ether (C12E4) on the water in isohexadecane emulsions were systematically studied. Ratios of the two-surfactant mixture, surfactant concentrations, and oil fraction were evaluated by gauging droplet size with the aid of photon correlation

Li-Ching Peng; Chi-Hsien Liu; Chang-Chin Kwan; Keh-Feng Huang

2010-01-01

212

BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS  

SciTech Connect

The aim of the project is to develop a knowledge base to help with the design of enhanced process for mobilizing and extracting untrapped oil. We emphasize on evaluating novel surfactant mixtures and on obtaining optimum combinations of the surfactants in chemical flooding EOR process. An understanding of the micellar shape and size is crucial since these physical properties directly determine the crude oil removal efficiency. Analytical ultracentrifugation experiments were used to test the multi-micelle model proposed earlier and formulate the relationships between mixed micelle formation and the surfactant structure. Information on partial specific volume of surfactants and their mixtures is required to treat analytical ultracentrifuge data. In the last report, it was noted that the partial specific volumes of the sugar-based surfactants obtained experimentally did not agree with those from theoretical calculations. A scrutiny of partial specific volumes of the four sugar-based surfactants revealed that conformational changes upon micelle formation are responsible for the large deviation. From sedimentation equilibrium experiments, two types of micelles were identified for the nonionic polyethylene surfactant and its mixtures with the sugar-based surfactant, dodecyl maltoside. The average aggregation numbers of n-dodecyl-{beta}-D-maltoside and nonyl phenol ethoxylated decyl ether agreed with those reported in literature using other techniques. Our study displayed, for the first time, that small micelles might coexist with large micelles at high concentrations due to unique structures of the surfactant although classical thermodynamic theory supports only one type of micelle. Initial dynamic light scattering results support the results for the same mixed surfactant system from analytical ultracentrifuge equilibrium technique. The implication of this finding lies in the fact that efficiency of oil recovery will be improved due to the large micellar size, its polymer-like fluidity and possible reduced adsorption on solids.

Prof. P. Somasundaran

2003-03-31

213

Influence of adsorbed milk protein type and surface concentration on the quiescent and shear stability of butteroil emulsions  

Microsoft Academic Search

Understanding of the relationship between adsorbed milk protein layer characteristics and stability of butteroil emulsions may be applied to create emulsions with specific properties such as ice cream emulsions (quiescently stable, destabilizing under shear) formulated without chemical surfactant. Emulsions created from butteroil (25%) with skim milk powder (SMP) (0.2–0.7%), whey protein hydrolysate (WPH) (1.6–2.1%), whey protein isolate (WPI) (0.2–0.7%) and

K. I. Segall; H. D. Goff

1999-01-01

214

Supercritical or compressed CO2 as a stimulus for tuning surfactant aggregations.  

PubMed

Surfactant assemblies have a wide range of applications in areas such as the chemical industry, material science, biology, and enhanced oil recovery. From both theoretical and practical perspectives, researchers have focused on tuning the aggregation behaviors of surfactants. Researchers commonly use solid and liquid compounds such as cosurfactants, acids, salts, and alcohols as stimuli for tuning the aggregation behaviors. However, these additives can present economic and environmental costs and can contaminate or modify the product. Therefore researchers would like to develop effective methods for tuning surfactant aggregation with easily removable, economical, and environmentally benign stimuli. Supercritical or compressed CO(2) is abundant, nontoxic, and nonflammable and can be recycled easily after use. Compressed CO(2) is quite soluble in many liquids, and the solubility depends on pressure and temperature. Therefore researchers can continuously influence the properties of liquid solvents by controlling the pressure or temperature of CO(2). In this Account, we briefly review our recent studies on tuning the aggregation behaviors of surfactants in different media using supercritical or compressed CO(2). Supercritical or compressed CO(2) serves as a versatile regulator of a variety of properties of surfactant assemblies. Using CO(2), we can switch the micellization of surfactants in water, adjust the properties of reverse micelles, enhance the stability of vesicles, and modify the switching transition between different surfactant assemblies. We can also tune the properties of emulsions, induce the formation of nanoemulsions, and construct novel microemulsions. With these CO(2)-responsive surfactant assemblies, we have synthesized functional materials, optimized chemical reaction conditions, and enhanced extraction and separation efficiencies. Compared with the conventional solid or liquid additives, CO(2) shows some obvious advantages as an agent for modifying surfactant aggregation. We can adjust the aggregation behaviors continuously by pressure and can easily remove CO(2) without contaminating the product, and the method is environmentally benign. We can explain the mechanisms for these effects on surfactant aggregation in terms of molecular interactions. These studies expand the areas of colloid and interface science, supercritical fluid science and technology, and chemical thermodynamics. We hope that the work will influence other fundamental and applied research in these areas. PMID:23106121

Zhang, Jianling; Han, Buxing

2012-10-29

215

Unexpected differences in dissolution behavior of tablets prepared from solid dispersions with a surfactant physically mixed or incorporated.  

PubMed

In a previous study, it was shown that the incorporation of poorly soluble drugs (BCS class II) in sugar glasses could largely increase the drug's dissolution rate [van Drooge, D.J., Hinrichs, W.L.J., Frijlink, H.W., 2004 b. Anomalous dissolution behaviour of tablets prepared from sugar glass-based solid dispersions. J. Control. Release 97, 441-452]. However, the application of this technology had little effect when high drug loads or fast dissolving sugars were applied due to uncontrolled crystallization of the drug in the near vicinity of the dissolving tablet. To solve this problem a surfactant, sodium lauryl sulphate (SLS), was incorporated in the sugar glass or physically mixed with it. Diazepam and fenofibrate were used as model drugs in this study. The dissolution behavior of tablets prepared from solid dispersions in which SLS was incorporated was strongly improved. Surprisingly, the dissolution rate of tablets prepared from physical mixtures of SLS and the solid dispersion was initially fast, but slowed down after about 10 min. The solid dispersions were characterized by DSC to explain this unexpected difference. These measurements revealed the existence of interaction of SLS with both the drug and the sugar in the solid dispersion when SLS was incorporated. It is hypothesized that due to this interaction, the dissolution of SLS was slowed down by which a high solubility of the drug in the near vicinity of the dissolving tablet is maintained during the whole dissolution process. Therefore, uncontrolled crystallization is effectively prevented. PMID:17804180

de Waard, H; Hinrichs, W L J; Visser, M R; Bologna, C; Frijlink, H W

2007-07-24

216

Recovery of anionic surfactant by RO process  

Microsoft Academic Search

Crosslinked sodium alginate (SA) membranes which have a protective polyelectrolyte complex layer at a membrane surface were prepared by a simple technique for the reverse osmosis separation of an anionic surfactant that has been used as an emulsifier in PTFE emulsion polymerization. With this technique, when a nascent SA film cast onto a glass plate was dipped in the reaction

C. K Yeom; C. U Kim; B. S Kim; K. J Kim; J. M Lee

1998-01-01

217

Factors in the occlusivity of aqueous emulsions. Influence of humectants  

Microsoft Academic Search

In this work, factors controlling occlusivity of emulsions when humectants are added were studied. Emulsions were prepared from perhydrosqualene (P.H.S.) and mineral oil using ester and ether non-ionic surfactants having various HLB values in the presence of sodium 5-pyrrolidone-2-carboxylate, sodium lactate, and urea each at concentrations of 0, 0.62, 1.25, 2.5, 3.75, and 5%. Physicochemical parameters analyzed included isotropic oily

T. H. CHOUDHURY; J. P. MARTY; A. M. ORECCHIONI

218

Self-similar shear thickening behavior in CTAB\\/NaSal surfactant solutions  

Microsoft Academic Search

The effect of salt concentration Cs on the critical shear rate required for the onset of shear thickening and apparent relaxation time of the shear-thickened phase, has been investigated systematically for dilute CTAB\\/NaSal solutions. Experimental data suggest a self-similar behavior of the critical shear rate and relaxation time as functions of Cs. Specifically, the former ~ Cs^(-6) whereas the latter

Mukund Vasudevan; Amy Shen; Bamin Khomami; Radhakrishna Sureshkumar

2008-01-01

219

Novel phase change behavior of n-eicosane in nanoporous silica: emulsion template preparation and structure characterization using small angle X-ray scattering.  

PubMed

Silica microcapsules with hierarchical pore structure are prepared using a one step emulsion templated hydrolysis method. Silica particles of around 100 nm with percolated nanosized pores are self-assembled into micrometer scale spherical shells. The porous structure serves as an ideal host for shape stabilization of melted organic compounds. Small angle X-ray scattering (SAXS) results show that the n-eicosane encapsulated in nanoporous silica consists of mass fractal structure with a fractal dimension of 2.1. n-Eicosane encapsulated in the nanosized pores exhibits novel phase change behavior. A large melting point drop from 37.0 to 28.8 °C is observed, which is attributed to the strong interaction between the n-eicosane molecules and the silica skeleton. PMID:23880873

Wang, Wei; Wang, Chongyun; Li, Wei; Fan, Xinxin; Wu, Zhonghua; Zheng, Jie; Li, Xingguo

2013-07-24

220

Crude Oil Emulsion Properties and Their Application to Heavy Oil Transportation  

Microsoft Academic Search

Crude Oil Emulsion Properties and their Application to Heavy Oil Transportation — Many advances have been made in the field of emulsions in recent years. Emulsion behavior is largely controlled by the properties of the adsorbed layers that stabilize the oil-water surfaces. The knowledge of surface tension alone is not sufficient to understand emulsion properties, and surface rheology plays an

D. Langevin; S. Poteau; I. Hénaut; J. F. Argillier

2004-01-01

221

Separation of Organic Compounds from Surfactant Solutions: A Review  

Microsoft Academic Search

This review summarizes the recent development in separation of emulsified organic compounds from surfactant solutions for surfactant reuse and\\/or surfactant?contaminant disposal. Three major principles have been employed for separating organic compounds and\\/or surfactants from aqueous solutions, namely, organic compound inter?phase mass transfer, surfactant micelle removal, and manipulation of surfactant solution phase behavior. Details of these principles and their applications are

Hefa Cheng; David A. Sabatini

2007-01-01

222

Lung surfactant.  

PubMed Central

Aspects of pulmonary surfactant are reviewed from a biochemical perspective. The major emphasis is on the lipid components of surfactant. Topics reviewed include surfactant composition, cellular and subcellular sites as well as pathways of biosynthesis of phosphatidylcholine, disaturated phosphatidylcholine and phosphatidylglycerol. The surfactant system in the developing fetus and neonate is considered in terms of phospholipid content and composition, rates of precursor incorporation, activities of individual enzymes of phospholipid synthesis and glycogen content and metabolism. The influence of the following hormones and other factors on lung maturation and surfactant production is discussed: glucocorticoids, thyroid hormone, estrogen, prolactin, cyclic AMP, beta-adrenergic and cholinergic agonists, prostaglandins and growth factors. The influence of maternal diabetes, fetal sex, stress and labor are also considered. Nonphysiologic and toxic agents which influence surfactant in the fetus, newborn and adult are reviewed.

Rooney, S A

1984-01-01

223

Cleavable surfactants  

Microsoft Academic Search

Cleavable surfactants are of interest for several reasons. Above all, the development of surfactants with weak bonds deliberately\\u000a built into the structure is driven by the need for improved biodegradability of amphiphiles. The breakdown may be catalyzed\\u000a by enzymes, and biodegradation would be the normal mechanism in sewage plants. Alternatively, the surfactant may degrade by\\u000a chemical means, e.g., induced by

Per-Erik Hellberg; Karin Bergström; Krister Holmberg

2000-01-01

224

Comparison of phase behavior between water soluble and insoluble surfactants at the air-water interface  

NASA Astrophysics Data System (ADS)

The surface phase behavior of 2-hydroxyethyl myristate (2-HEM) has been studied in Langmuir monolayers by measuring surface pressure ( ?)-area ( A) isotherms with a film balance and observing monolayer morphology with a Brewster angle microscope (BAM). These results are compared with the phase behavior of 2-hydroxyethyl laurate (2-HEL) in Gibbs monolayers studied by measuring ?-time ( t) curves and observing monolayer morphology. The ?- A isotherms of 2-HEM show a first-order phase transition from a liquid expanded (LE) phase to a liquid condensed (LC) phase in the temperature range between 5 and 35 °C whereas the ?- t curves of 2-HEL represent a similar phase transition in the temperature range between 2 and 25 °C. The critical surface pressure, ?c necessary for the phase transitions increases with increasing temperature in both the cases. The LC domains formed in 2-HEM show circular shapes, which are independent of the temperature. In contrast, the circular domains having stripe texture formed at lower temperatures show a shape transition to fingering domains with uniform brightness at 15 °C. The amphiphile, 2-HEM having 13-carbon chain has higher line tension than 2-HEL that has 11-carbon chain as tail. Thus, for 2-HEM, this high line tension always dominates over other factors giving rise to circular domains at the all studied temperatures.

Hossain, Md. Mufazzal; Iimura, Kenichi; Kato, Teiji

225

Behavior of asphaltene model compounds at w/o interfaces.  

PubMed

Asphaltenes, present in significant amounts in heavy crude oil, contains subfractions capable of stabilizing water-in-oil emulsions. Still, the composition of these subfractions is not known in detail, and the actual mechanism behind emulsion stability is dependent on perceived interfacial concentrations and compositions. This study aims at utilizing polyaromatic surfactants which contains an acidic moiety as model compounds for the surface-active subfraction of asphaltenes. A modified pulse-field gradient (PFG) NMR method has been used to study droplet sizes and stability of emulsions prepared with asphaltene model compounds. The method has been compared to the standard microscopy droplet counting method. Arithmetic and volumetric mean droplet sizes as a function of surfactant concentration and water content clearly showed that the interfacial area was dependent on the available surfactant at the emulsion interface. Adsorption of the model compounds onto hydrophilic silica has been investigated by UV depletion, and minor differences in the chemical structure of the model compounds caused significant differences in the affinity toward this highly polar surface. The cross-sectional areas obtained have been compared to areas from the surface-to-volume ratio found by NMR and gave similar results for one of the two model compounds. The mean molecular area for this compound suggested a tilted geometry of the aromatic core with respect to the interface, which has also been proposed for real asphaltenic samples. The film behavior was further investigated using a liquid-liquid Langmuir trough supporting the ability to form stable interfacial films. This study supports that acidic, or strong hydrogen-bonding fractions, can promote stable water-in-oil emulsion. The use of model compounds opens up for studying emulsion behavior and demulsifier efficiency based on true interfacial concentrations rather than perceived interfaces. PMID:19852481

Nordgård, Erland L; Sørland, Geir; Sjöblom, Johan

2010-02-16

226

Rheological Behavior of Aqueous Solutions of Cationic Guar in Presence of Oppositely Charged Surfactant  

NASA Astrophysics Data System (ADS)

The cationic guar (CG) is synthesized and the rheological behavior of aqueous solutions of CG in the presence of sodium dodecyl sulfate (SDS) is studied in detail. The steady viscosity measurements show that the zero shear viscosity enhancement can be almost 3 orders of magnitude as the concentration of SDS increases from 0 to 0.043%. The gel-like formation is observed as the concentration of SDS is greater than 0.016%. The oscillatory rheological measurements of CG solutions in the presence of SDS show that the crossover modulus is almost independent of the concentration of SDS whereas the apparent relaxation time increases swiftly upon increasing the concentration of SDS. The experimental results indicate that the strength rather than the number of the cross-links is greatly affected by SDS molecules. The mechanism concerning the effect of SDS upon the rheology of CG solutions can be coined by the two-stage model. Before the formation of cross-links at the critical concentration, the electrostatic interaction between SDS and cationic site of CG chains plays a key role and the SDS molecules bind to CG chains through the electrostatic interaction. After the formation of cross-links at the concentration greater than the critical concentration, the cooperative hydrophobic interaction become dominant and SDS molecules bind to the cross-links through the hydrophobic interaction. The rheological behavior of aqueous solutions of CG in the presence of SDS is chiefly determined by the micelle-like cross-links between CG chains. In fact, the flow activation energy of CG solution, obtained from the temperature dependence of the apparent relaxation time, falls in the range of transferring a hydrophobic tail of SDS from the micelle to an aqueous environment.

Li, Hua-zhen; Yang, Hai-yang; Xie, Yong-jun; Li, Hua-yu; He, Ping-sheng

2010-08-01

227

Preparation and characterization of brushite crystals using high internal phase emulsion  

Microsoft Academic Search

Various morphologies of brushite crystals were successfully synthesized using oil-in-water high internal phase emulsion stabilized\\u000a by surfactants with various polyoxyethylene chain lengths for the first time. Rheological measurements had proven that such\\u000a emulsion was a highly stable reaction media for the synthesis of particulate and porous brushite crystals. Rheological properties\\u000a of the emulsion with and without the presence of crystal

H. N. Lim; A. Kassim; N. M. Huang; M. A. Yarmo; P. S. Khiew; W. S. Chiu

2009-01-01

228

Treatment of oil-in-water emulsions by coagulation and dissolved-air flotation  

Microsoft Academic Search

The treatment of oil-in-water emulsions containing n-octane (used as simulated wastewater) was investigated by means of dissolved-air flotation jar-tests. The effect of several parameters on flotation efficiency for separation of the emulsified oil was examined, namely, (a) the presence the nonionic surfactant Tween 80, used for the stabilization of the emulsions, (b) the initial pH value of the emulsions, (c)

A. I Zouboulis; A Avranas

2000-01-01

229

Coalescence stability of emulsions containing globular milk proteins  

Microsoft Academic Search

This review summarizes a large set of related experimental results about protein adsorption and drop coalescence in emulsions, stabilized by globular milk proteins, ?-lactoglobulin (BLG) or whey protein concentrate (WPC). First, we consider the effect of drop coalescence on the mean drop size, d32, during emulsification. Two regimes of emulsification, surfactant-rich (negligible drop coalescence) and surfactant-poor (significant drop coalescence) are

Slavka Tcholakova; Nikolai D. Denkov; Ivan B. Ivanov; Bruce Campbell

2006-01-01

230

Emulsions: Principles and Preparation  

Microsoft Academic Search

Emulsions are mixtures of fluids that are immiscible. Usually one fluid is present as small droplets in another phase. There\\u000a are emulsions of oil in water, called oil-inwater emulsions (abbreviated as O\\/W), but also emulsions of water in oil (W\\/O).\\u000a The droplet phase is called the dispersed phase, the surrounding phase the continuous phase. Emulsions are important in a\\u000a great

Remko M. Boom

231

Fouling and rejection behavior of ceramic and polymer-modified ceramic membranes for ultrafiltration of oil-in-water emulsions and microemulsions  

Microsoft Academic Search

The effectiveness of poly(vinylpyrrolidone) (PVP)-modification of a zirconia-based ultrafiltration membrane was investigated for the treatment of oil-in-water (o\\/w) emulsions. Fouling, hydraulic permeability, flux decline, and solute rejection for modified and native membranes were evaluated using a diagnostic o\\/w emulsion as well as an emulsion prepared using a commercial cutting oil. The native membrane was irreversibly fouled by both the o\\/w

Ron S. Faibish; Yoram Cohen

2001-01-01

232

Recovery of phenols using liquid surfactant membranes prepared with newly synthesized surfactants  

SciTech Connect

Extraction and stripping equilibrium of phenol, p-cresol, and p-chlorophenol were studied with an organic solution containing a newly synthesized surfactant and an aqueous alkaline solution as a stripping phase. A cationic surfactant showed the highest extraction ratio of phenol among several surfactants used in this study. The magnitude of phenol extracted from water was in the order phenol < p-chlorophenol < p-cresol. The stripping of phenol extracted in the organic solution was quantitatively accomplished with an alkaline solution of high concentration except for the case of cationic surfactants. Extraction of phenol and its derivatives by liquid surfactant membranes containing a newly synthesized surfactant as an emulsifier was carried out in a stirred cell. The effects of various parameters (such as a surfactant and alkaline concentration, the kind of surfactant, and the alkali composition) on the extraction efficiency of phenol were examined along with demulsification of W/O emulsions. On the basis of the stability of surfactants against alkaline solutions used as a receiving phase, cationic surfactants which did not involve an ester or amide bond in their molecule appeared to be among the best surfactants available for phenol removal in liquid membrane operations. The efficiency of phenol recovery with sodium hydroxide as a stripping agent was much higher than that with sodium carbonate; however the efficiency of the emulsions decreased with an increase in the content of sodium hydroxide in the mixed alkaline solutions of sodium hydroxide and sodium carbonate. In the design of an efficient recovery process of phenols by LSMs, the composition of the alkaline solution was one of the key factors. Under optimal conditions, phenolic derivates could be recovered in a few minutes.

Kakoi, Takahiko; Goto, Masahiro; Natsukawa, Soichi [Kyushu Univ., Fukuoka (Japan)] [and others

1996-01-01

233

Aggregation behavior of a fluorinated surfactant in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid.  

PubMed

The cationic fluorinated surfactant, FC-4, unlike other surfactants, forms micelles in the room temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (bmimTf2N). Surface tension, freeze-fracture transmission electron microscopy, 19F NMR, 1H NMR, and Fourier transform infrared measurements revealed that (i) the FC-4 cation forms an ion pair with the Tf2N anion, (ii) the ion pairs undergo association to form premicellar aggregates, and (iii) the premicellar aggregates transform into micelles at the critical micelle concentration (CMC). The thermodynamic parameters for micelle formation derived from the temperature dependence of the CMC demonstrated that the solvophobic interaction between the solvophobic tails of the surfactant molecules is rather weak in bmimTf2N compared with other ionic liquids, in accordance with the observation that surfactants do not readily form micelles in bmimTf2N. The fact that FC-4 forms micelles in such an inconvenient solvent is attributed to the ion-pair formation between the surfactant cation and the ionic liquid anion. PMID:19441844

Li, Na; Zhang, Shaohua; Zheng, Liqiang; Inoue, Tohru

2009-09-15

234

Triblock copolymers as destabilizers of water-in-crude oil emulsions  

Microsoft Academic Search

Water-in-oil emulsions are formed during crude oil exploitation. Asphaltenes aggregates (crude oil natural surfactants) are known to form viscoelastic film preventing coalescence of water droplets. For oil refining purpose, demulsifying surfactants are commonly used. The present work investigates the relationship between the structure of four triblock copolymers, their interfacial properties and their demulsifying capacity. The copolymers are formed by two

A. Le Follotec; I. Pezron; C. Noik; C. Dalmazzone; L. Metlas-Komunjer

2010-01-01

235

Recent advances in the combustion of water fuel emulsion  

Microsoft Academic Search

Recent advances in the combustion of water fuel emulsion which consists of base fuel and water doped with or without a trace content of surfactant are reviewed. The focus is on the fundamental mechanism relevant to the micro-explosion phenomena leading to the secondary atomization which is not common to the combustion of pure fuel. Described at first are the kinetic

T. Kadota; H. Yamasaki

2002-01-01

236

Emulsion Polymerized Polystyrene\\/Montmorillonite Nanocomposite and its Viscoelastic Characteristics  

Microsoft Academic Search

A novel polystyrene (PS)\\/clay nanocomposite was synthesized using a simple emulsion polymerization method in the presence of sodium ion exchanged montmorillonite (Na?MMT). Prior to the radical polymerization procedure with potassium persulfate (KPS) as an initiator, the hydrophobic styrene monomer was intercalated into hydrophilic clay layers using sodium dodecyl sulfate (SDS) as a surfactant. The FTIR spectra of the products showed

Bong Jun Park; Tae Heon Kim; Hyoung Jin Choi; Jae Heung Lee

2007-01-01

237

A novel method for the synthesis of CdS nanoparticles without surfactant  

Microsoft Academic Search

Cadmium sulfide nanoparticles with a hexagonal phase (?10nm) were prepared at a relatively low temperature (70°C). This synthesis was carried out shortly (30min) through a new micro-emulsion (O\\/W) induced by ultrasound without surfactant. Ultrasound can provide an excess energy for new interface formation and obtain emulsions even in the absence of surfactants. This technique avoids some problems that normally exist

N. Ghows; M. H. Entezari

2011-01-01

238

Influence of surfactant charge on antimicrobial efficacy of surfactant-stabilized thyme oil nanoemulsions.  

PubMed

Thyme oil-in-water nanoemulsions stabilized by a nonionic surfactant (Tween 80, T80) were prepared as potential antimicrobial delivery systems (pH 4). The nanoemulsions were highly unstable to droplet growth and phase separation, which was attributed to Ostwald ripening due to the relatively high water solubility of thyme oil. Ostwald ripening could be inhibited by incorporating ?75% of corn oil (a hydrophobic material with a low water solubility) into the nanoemulsion droplets. The electrical characteristics of the droplets in the nanoemulsions were varied by incorporating ionic surfactants with different charges after homogenization: a cationic surfactant (lauric arginate, LAE) or an anionic surfactant (sodium dodecyl sulfate, SDS). The antifungal activity of nanoemulsions containing positive, negative, or neutral thymol droplets was then conducted against four strains of acid-resistant spoilage yeasts: Zygosaccharomyces bailli, Saccharomyces cerevisiae, Brettanomyces bruxellensis, and Brettanomyces naardenensis. The antifungal properties of the three surfactants (T80, LAE, SDS) were also tested in the absence of thymol droplets. Both ionic surfactants showed strong antifungal activity in the absence of thymol droplets, but no antimicrobial activity in their presence. This effect was attributed to partitioning of the antimicrobial surfactant molecules between the oil droplet and microbial surfaces, thereby reducing the effective concentration of active surfactants available to act as antimicrobials. This study shows oil droplets may decrease the efficacy of surfactant-based antimicrobials, which has important consequences for formulating effective antimicrobial agents for utilization in emulsion-based food and beverage products. PMID:21520914

Ziani, Khalid; Chang, Yuhua; McLandsborough, Lynne; McClements, David Julian

2011-05-06

239

FRAGRANCE EMULSIONS STABILIZED BY A TRIBLOCK COPOLYMER  

Microsoft Academic Search

The phase diagram was determined of the system a fragrance oil, phenethyl alcohol, a commercial triblock copolymer, PE\\/L101, and water. The stability of emulsions containing 95 wt% water and various amounts of the fragrance and polymer was investigated both visually and with the aid of an optical microscope. The stability of the two-phase emulsions was explained through the interfacial behavior

Zhiqiang Zhang; Jennifer L. Barber; Stig E. Friberg; Patricia A. Aikens

2000-01-01

240

Impact of emulsion-based drug delivery systems on intestinal permeability and drug release kinetics.  

PubMed

Lipid based drug delivery systems, and in particular self-emulsifying drug delivery systems (SEDDS), show great potential for enhancing oral bioavailability but have not been broadly applied, largely due to lack of general formulation guidance. To help understand how formulation design influences physicochemical emulsion properties and associated function in the gastrointestinal environment, a range of twenty-seven representative self-emulsifying formulations were investigated. Two key functions of emulsion-based drug delivery systems, permeability enhancement and drug release, were studied and statistically related to three formulation properties - oil structure, surfactant hydrophilic liphophilic balance (HLB) values, and surfactant-to-oil ratio. Three surfactants with HLB values ranging from 10 to 15 and three structurally different oils (long chain triglyceride, medium chain triglyceride, and propylene glycol dicaprylate/dicaprate) were combined at three different weight ratios (1:1, 5:1, 9:1). Unstable formulations of low HLB surfactant (HLB=10) had a toxic effect on cells at high (1:1) surfactant concentrations, indicating the importance of formulation stability for minimizing toxicity. Results also indicate that high HLB surfactant (Tween 80) loosens tight junction at high (1:1) surfactant concentrations. Release coefficients for each emulsion system were calculated. Incorporation of a long chain triglyceride (Soybean oil) as the oil phase increased the drug release rate constant. These results help establish an initial foundation for relating emulsion function to formulation design and enabling bioavailability optimization across a broad, representative range of SEDDS formulations. PMID:19850092

Buyukozturk, Fulden; Benneyan, James C; Carrier, Rebecca L

2009-10-20

241

Stretching and colliding surfactant-coated drops  

NASA Astrophysics Data System (ADS)

Equilibrium and kinetic properties of interfacial tension govern the structure, dynamics, stability and performance of immiscible fluids, such as polymer blends, detergents and reaction and separation media. These properties also play a substantial role in microcapillary devices. Using extension flow to stretch drops, we develop a microfluidic approach to probe equilibrium and kinetic surfactant adsorption. We also monitor drop population dynamics in simple shear (over a wide range of capillary number) and identify surfactant properties and mechanisms that regulate the coalescence of drops in emulsions.

Hudson, Steven

2005-03-01

242

Incorporation of small quantities of surfactants as a way to improve the rheological and diffusional behavior of carbopol gels  

Microsoft Academic Search

This paper analyzes the effects of Tween 80, Pluronic F-127, sodium dodecylsulfate (SDS), and benzalkonium chloride on the macro and microviscosity of Carbopol® 934NF (0.25–0.50 g\\/dl) pharmaceutical gels. Carbopol\\/surfactant interactions, which were reflected in changes in the intrinsic viscosity of the polymer and in shifts of IR spectra bands of films, considerably modified the rheological properties of the gel (flow

Rafael Barreiro-Iglesias; Carmen Alvarez-Lorenzo; Angel Concheiro

2001-01-01

243

Microchannel emulsification using gelatin and surfactant-free coacervate microencapsulation  

Microsoft Academic Search

In this study, we investigated the use of microchannel (MC) emulsifications in producing monodisperse gelatin\\/acacia complex coacervate microcapsules of soybean oil. This is considered to be a novel method for preparing monodisperse O\\/W and W\\/O emulsions. Generally, surfactants are necessary for MC emulsification, but they can also inhibit the coacervation process. In this study, we investigated a surfactant-free system. First,

Kei Nakagawa; Satoshi Iwamoto; Mitsutoshi Nakajima; Atsushi Shono; Kazumi Satoh

2004-01-01

244

Optimization of the flocculation stage in a model system of a food emulsion waste using chitosan as polyelectrolyte  

Microsoft Academic Search

The influence of different factors on the dose of chitosan necessary to neutralize electrical charge and to get flocculation in a model system of a sunflower oil\\/ water emulsion was analyzed. These factors included: ionic strength, pH, size of the drops in the emulsion, concentration of oil and surfactant and type of emulsifier (sodium dodecyl and tetradecyl sulfate). Results showed

A. Pinotti; A. Bevilacqua; N. Zaritzky

1997-01-01

245

Dehydration of oil waste emulsions by means of flocculants  

SciTech Connect

Oil waste emulsions are formed in the course of pumping petroleum crudes and products and are collected from the surfaces of equipment in recirculating water systems and wastewater disposal facilities (oil separators, sand traps, oil traps, holding pits for accidental spills, settlers, ponds, sludge accumulators, and so on). Emulsions are also obtained in the course of cleaning equipment in crude oil desalting and dehydration units. Such emulsions are stable, structurized systems that are very resistant to dewatering by heating and settling in separator tanks. In order to break stabilized emulsions, i.e., in order to ensure complete coalescence of drops when they collide, it is not sufficient to increase the forces of mutual attraction of drops at the moment of collision; in addition, the protective shell must be either destroyed or weakened. Demulsifying agents, or surfactants, will displace the stabilizers. This report is concerned with demulsifier efficiency.

Gandurina, L.V.; Butseva, L.N.; Shtondina, V.S.

1995-05-01

246

Synergistic effects of polyglycerol ester of polyricinoleic acid and sodium caseinate on the stabilisation of water–oil–water emulsions  

Microsoft Academic Search

The inherent thermodynamic instability of water–oil–water (W\\/O\\/W) emulsions has restrictions for their application in food systems. The objective of this study was to develop a food grade W\\/O\\/W emulsions with high yield and stability using minimal concentrations of surfactants. Emulsions were prepared using soybean oil, polyglycerol ester of polyricinoleic acid (PGPR) alone or in combination with sodium caseinate (NaCN) as

Jiahong Su; John Flanagan; Yacine Hemar; Harjinder Singh

2006-01-01

247

Accelerated Stability Testing of a Water-in-Oil Emulsion  

Microsoft Academic Search

Non-optimal or non-predictable stability properties of emulsions can be limiting for the applications of emulsions. Therefore, it is of general interest to predict stability behavior. In the present study, accelerated stability testing employing elevated temperatures with good accuracy predicted long-term stability of a w\\/o emulsion stabilized with polyglycerol polyricinoleate (PG PR) kept at 4°C. It is argued that elevated temperature

S. Bjerregaard; C. Vermehren; I. Söderberg; S. Frokjaer

2001-01-01

248

Blend of alkyl phenol ethoxylates and alkyl phenol glycoxylates and their use as surfactants  

SciTech Connect

Nonionic surfactant compositions useful in forming stable emulsions with oil in saline solutions comprising a blend of: at least one alkyl phenol ethoxylate and at least one alkyl phenol glycoxylate. These surfactant compositions may be employed in enhanced oil recovery processes and other applications where good emulsification and high salinity tolerances are required such as textiles, leather, dairy, concrete grinding aids and drilling muds.

Grolitzer, M. A.

1985-11-12

249

Auto-ignition and micro-explosion behaviors of droplet arrays of water-in-fuel emulsion  

Microsoft Academic Search

The characteristics of auto-ignition and micro-explosion behaviors of one-dimensional arrays of fuel droplets suspended in\\u000a a chamber with high surrounding temperature were investigated experimentally with various droplet spacings, numbers of droplet\\u000a and surrounding temperatures. The fuels used were pure n-decane and emulsified n-decane with varied water contents ranging\\u000a from 10 to 30%. All experiments were performed under atmospheric conditions with

I. C. Jeong; K. H. Lee

2008-01-01

250

Study on preparation and formation mechanism of n-alkanol/water emulsion using alpha-cyclodextrin.  

PubMed

Surfactants are usually used for the preparation of emulsions; however, some have an adverse effect on the human body such as skin irritation, hemolysis, and protein denaturation, etc. In this study, we examined the preparation and formation mechanism of n-alkanol/water emulsions using alpha-cyclodextrin (alpha-CD) as an emulsifier. Emulsions were prepared by mixing oil and water phases for 4 min at 2500 rpm using a vortex mixer. The mechanism of emulsification was investigated with some physico-chemical techniques. From phase diagrams of n-alkanol/alpha-CD/water systems, the emulsion phase extended as the chain length of n-alkanols and the amount of alpha-CD added increased. Furthermore, the emulsion was not formed in the region where the n-alkanol/alpha-CD complex didn't precipitate; however, the emulsion was formed in the region where the complex precipitated. In addition, it was clear that the emulsions have a yield stress value and correspond to the Maxwell model from rheological measurement. Our experiments clearly showed that the stable emulsions are formed because the precipitated complexes form a dense film at the oil-water interface and prevent aggregation among dispersed phases. Furthermore, it is suggested that the creation of a three-dimensional network structure formed by precipitated complexes in the continuous phase contributes to the stabilization of the emulsion. Thus, we concluded that the n-alkanol/water emulsions using alpha-cyclodextrin were a kind of the Pickering emulsion. PMID:17978523

Hashizaki, Kaname; Kageyama, Takashi; Inoue, Motoki; Taguchi, Hiroyuki; Ueda, Haruhisa; Saito, Yoshihiro

2007-11-01

251

Low-energy formation of edible nanoemulsions: factors influencing droplet size produced by emulsion phase inversion.  

PubMed

Nanoemulsions can be used for the encapsulation and oral delivery of bioactive lipophilic components, such as nutraceuticals and pharmaceuticals. There is growing interest in the utilization of low-energy methods to produce edible nanoemulsions. In this study, we examined the influence of system composition and preparation conditions on the formation of edible nanoemulsions by the emulsion phase inversion (EPI) method. The EPI method involves titrating an aqueous phase (water) into an organic phase (oil+hydrophilic surfactant). The influence of oil type, surfactant type, surfactant-to-oil ratio (SOR), and initial surfactant location on the particle size distributions of the emulsions was studied. The droplet size produced by this method depended on: (i) oil type: medium chain triglycerides (MCT)surfactant type: Tween 80surfactant concentration: smaller droplets were produced at higher SOR; (iv) surfactant location: surfactant initially in oil<surfactant initially in water. The low energy method (EPI) was also compared to a high energy method (microfluidization). Small droplets (d<160 nm) could be produced by both methods, but much less surfactant was needed for the high energy method (SOR?0.1) than the low energy method (SOR?0.7). PMID:22981587

Ostertag, Felix; Weiss, Jochen; McClements, David Julian

2012-08-25

252

Oil-in-alcohol highly concentrated emulsions as templates for the preparation of macroporous materials.  

PubMed

New oil-in-alcohol highly concentrated emulsions were formulated and were used as a templates to obtain macroporous poly(furfuryl alcohol) monoliths by a one-step method. The oil-in-alcohol highly concentrated emulsions were prepared by stepwise addition of the oil phase to the surfactant-alcohol solution and were characterized by optical microscopy and by laser diffraction. The typical structure of highly concentrated emulsions, with close-packed polyhedral droplets, has been observed. Poly(furfuryl alcohol) monoliths were obtained by polymerizing in the external phase of these emulsions. These materials are mainly macroporous and retain the size distribution and morphology from the highly concentrated emulsions. The internal structure of the monoliths was observed by scanning electron microscopy. The images showed an interconnected network with pore size similar to the droplet size of the highly concentrated emulsions used as templates. PMID:22489569

Vílchez, Susana; Pérez-Carrillo, Lourdes A; Miras, Jonathan; Solans, Conxita; Esquena, Jordi

2012-05-11

253

Swelling Behavior of Poly{N-(3-(dimethylaminopropyl)) methacrylamide-co-acrylamide} Hydrogels in Aqueous Solutions of Surfactants  

Microsoft Academic Search

Temperature sensitive poly{N-(3-(dimethylaminopropyl))methacrylamide- co-acrylamide} (P(DMAPMA-co-AAm)) hydrogels were prepared by the free-radical crosslinking copolymerization of corresponding monomers in water with N,N-methyl- enebisacrylamide as the crosslinker, ammonium persulfate as the initiator, and N,N,N0,N0-tetramethylethylenediamine as the activator. The swelling equilibrium of the P(DMAPMA-co-AAm) hydrogels was investigated as a function of temperature in aqueous solutions of the anionic surfactant sodium dodecyl sulfate and the

TUNCER CAYKARA; MELIKE DEMIRAY; OLGUN GUVEN

254

Optimization of Surfactant Mixtures and Their Interfacial Behavior for Advanced Oil Recovery, Annual Report, September 30, 1999-September 30, 2000  

SciTech Connect

The goal of this report is to develop improved extraction processes to mobilize and produce the oil left untapped using conventional techniques. Current chemical schemes for recovering the residual oil have been in general less than satisfactory. High cost of the processes as well as significant loss of chemicals by adsorption on reservoir materials and precipitation has limited the utility of chemical-flooding operations. There is a need to develop cost-effective, improved reagent schemes to increase recovery from domestic oil reservoirs. The goal of the report was to develop and evaluate novel mixtures of surfactants for improved oil recovery.

Somasundaran, Prof. P.

2001-04-04

255

Effect of surfactants used for binder synthesis on the properties of latex paints  

Microsoft Academic Search

Surfactants are commonly used during emulsion polymerization to produce stable dispersions of polymer particles for applications such as paints, adhesives and other coating applications. Surfactants can improve properties such as shelf-life, freeze–thaw stability and mechanical stability. However, the addition of surfactants can also have a negative effect on end-use properties, such as the water resistance of the coating. The type

Lauren N. Butler; Christopher M. Fellows; Robert G. Gilbert

2005-01-01

256

Influence of experimental parameters on the characteristics of poly(lactic acid) nanoparticles prepared by a double emulsion method  

Microsoft Academic Search

Nanoparticles were prepared by the double emulsion method (w\\/o\\/w), using methylene chloride as an organic solvent and polyvinyl alcohol (PVA) or human serum albumin (HSA) as a surfactant. Experimental parameters such as the preparation temperature, the solvent evaporation method, the internal aqueous phase volume, the surfactant concentration and the polymer molecular weight were investigated for particle size, the zeta potential,

M. F Zambaux; F Bonneaux; R Gref; P Maincent; E Dellacherie; M. J Alonso; P Labrude; C Vigneron

1998-01-01

257

Properties of Glucosamide-Based Tetrasiloxane Surfactants  

Microsoft Academic Search

The interfacial properties of new glucosamide-based tetrasiloxane surfactants were studied. Members of the glucosamide-based tetrasiloxane surfactants reduce the surface tension of water to approximately 21 mN · m at concentration levels of 10 mol · L. The wetting and spreading behavior of the glucosamide-based tetrasiloxane surfactants on Teflon and Paraffin were investigated and compared with that of trisiloxane. A new glucosamide-based tetrasiloxane ? shows the best

Wanxu Wang; Shujun Wang; Zhiping Du; Guoyong Wang; Liang Wang

2011-01-01

258

Properties of Glucosamide-Based Tetrasiloxane Surfactants  

Microsoft Academic Search

The interfacial properties of new glucosamide-based tetrasiloxane surfactants were studied. Members of the glucosamide-based tetrasiloxane surfactants reduce the surface tension of water to approximately 21 mN · m at concentration levels of 10 mol · L. The wetting and spreading behavior of the glucosamide-based tetrasiloxane surfactants on Teflon and Paraffin were investigated and compared with that of trisiloxane. A new glucosamide-based tetrasiloxane ? shows the

Wanxu Wang; Shujun Wang; Zhiping Du; Guoyong Wang; Liang Wang

2012-01-01

259

Flocculation of deformable emulsion droplets. 2: Interaction energy  

SciTech Connect

The effect of different factors (drop radius, interfacial tension, Hamaker constant, electrolyte, micellar concentrations, etc.) on the interaction energy of emulsion droplets is studied theoretically. It is demonstrated that the deformation of the colliding droplets considerably affects the interaction energy. The contributions of the electrostatic, van der Waals, depletion, steric, and oscillatory surface forces, as well as for the surface stretching and bending energies, are estimated and discussed. The calculations show that the droplets interact as nondeformed spheres when the attractive interactions are weak. At stronger attractions an equilibrium plane parallel film is formed between the droplets, corresponding to minimum interaction energy of the system. For droplets in concentrated micellar surfactant solutions the oscillatory surface forces become operative and one can observe several minima of the energy surface,each corresponding to a metastable state with a different number of micellar layers inside the film formed between the droplets. The present theoretical analysis can find applications in predicting the behavior and stability of miniemulsions (containing micrometer and submicrometer droplets), as well as in interpretation of data obtained by light scattering, phase behavior, rheological and osmotic pressure measurements, etc.

Petsev, D.N.; Denkov, N.D.; Kralchevsky, P.A. [Univ. of Sofia (Bulgaria). Lab. of Thermodynamics and Physicochemical Hydrodynamics

1995-12-01

260

Oil emulsions of fluorosilicone fluids  

SciTech Connect

Emulsions of fluorosilicone fluids in mineral oil are disclosed. These emulsions are stabilized by a polydimethylsiloxane-polybutadiene copolymer or a polydimethylsiloxane-hydrogenated polybutadiene copplymer. The emulsions are an effective foam suppressant for organic liquids, especially crude petroleum.

Keil, J. W.

1985-08-27

261

Demulsification of bitumen emulsions  

SciTech Connect

A process for recovering bitumen from oil-in-water (O/W) emulsions is disclosed wherein water-soluble demulsifiers are used. These demulsifiers are salts of polymers and/or co-polymers of specific cationic monomers. To resolve the bituminous petroleum emulsions, the process is carried out between 25/sup 0/ and 160/sup 0/C. wherein the demulsifier of the invention is contacted with the bituminous emulsion.

McCoy, D.R.; McEntire, E.E.

1983-09-20

262

Demulsification of bitumen emulsions  

SciTech Connect

A process for recovering bitumen from oil-in-water (o/w) emulsions is disclosed wherein water soluble demulsifiers are used. These demulsifiers are hydrophilic polyurethanes wherein the ethylene oxide content of the polyol portion of the polyurethane is greater than about 70% by weight. To resolve the bituminous petroleum emulsions, the process is carried out between 25 and 1200 C wherein the demulsifier of the invention is contacted with the bituminous emulsion.

Gipson, R.M.; Laberge, C.L.; Mccoy, D.R.; Young, K.B.

1982-03-23

263

Interactions between polymers and surfactants  

SciTech Connect

A surfactant film (at the water/air interface, or in a bilayer) is exposed to a solution of a neutral, flexible, polymer. Depending on the interactions, and on the Langmuir pressure II of the pure surfactant film, the authors expected to find three types of behavior: (I) the polymer does not absorb; (II) the polymer absorbs and mixes with the surfactant; (III) the polymer absorbs but segregates from the surfactant. Their interest here is in case II. They predict that (a) bilayers become rigid; (b) bilayers, exposed to polymer on one side only, tend to bend strongly; (c) the surface viscosity of monolayers or bilayers is considerably increased; soap films or foams, which usually drain by turbulent (two-dimensional) flows, may be stabilized in case II.

de Gennes, P.G. (College de France, Paris (France))

1990-11-01

264

Influence of thickness in the holographic emulsion composed by rosin and BPB dye  

NASA Astrophysics Data System (ADS)

We analyze diffraction gratings behavior recorded on a phase holographic emulsion. This emulsion is composed with resin and bromophenol blue dye (BPB) they have a diffraction efficiency (?) from 0.22 to 0.615% order, and their thickness are different in the holographic emulsion.

Ibarra, Juan C.; Ortiz-Gutierrez, Mauricio; Olivares-Perez, Arturo; Perez-Cortes, Mario

2004-10-01

265

Invert emulsion as a medium for fungal lipase activity  

Microsoft Academic Search

An extracellular lipase from the fungusPythium ultimum was active in an invert [water-in-oil] emulsion consisting of 4% water emulsified into edible oils with taurocholic acid\\u000a as the surfactant. The pH range for optimum lipolytic activity was 7.5–8.5, and the optimum temperature for activity was 45C.\\u000a Specific activity of the purified lipase was 919.5 mol\\/min\\/mg protein in the invert emulsion. Water

Zahid Mozaffar; John D. Weete

1995-01-01

266

Surfactant compositions  

SciTech Connect

A surfactant composition is described for subsequent addition to a soap slurring comprising an acyloxy alkane sulfonate salt. The sulfonate salt is present in an amount by weight of about 44 percent of about 56 percent. The polyol is present in an amount by weight of about 2 percent to about 6 percent, and water is present in an amount by weight of 26 to 36 percent. The composition constituting a solid reversible solution at ambient temperature and having a solids content of about 58 to 72 percent, whereby subsequent addition of the surfactant composition to a soap slurry results in formation of a soap/detergent bar having a smooth texture, uniform wear properties and a lack of grittiness.

Novakovic, M.; Abend, P.G.

1987-09-29

267

Surfactant survey  

Microsoft Academic Search

Conclusions  This study emphasizes the differences in properties required of surfactants for various application, the large and growing\\u000a number of uses requiring more than 500,000 pounds per year, and the constantly changing pattern of use, making most of the\\u000a recent estimates of volume distribution obsolete.\\u000a \\u000a For some time it has been customary to estimate the household market as 75–80% of the

Carl Pacifico; M. E. Ionescu

1957-01-01

268

Direct measurement of contact angles of silica particles in relation to double inversion of pickering emulsions.  

PubMed

In an alkane-water system containing submicrometer silica particles at high pH, double emulsion inversion from oil-in-water (o/w) to water-in-oil (w/o) to oil-in-water can be effected by increasing the concentration of a dichain cationic surfactant in water. The contact angle ? of the particles at the planar oil-water interface has been measured directly using freeze-fracture shadow-casting cryo-scanning electron microscopy, enabling single-particle measurements of high accuracy. ? passes through a maximum with respect to surfactant concentration. It is shown that particles undergo a hydrophilic-hydrophobic-hydrophilic transition corresponding closely to the o/w-w/o-o/w transformation observed in emulsions. These results unequivocally link the single-particle contact angles to the type of particle-stabilized emulsion, confirming macroscopic emulsion inversion on the microscopic level. PMID:23570266

Binks, Bernard Paul; Isa, Lucio; Tyowua, Andrew Terhemen

2013-04-09

269

Ambient and High-Temperature Calorimetry of Commercial Surfactants: Project BE4A, Milestone 8, FY89 Annual Research Plan.  

National Technical Information Service (NTIS)

Knowledge of the critical micelle concentration (CMC) is required for the effective use of surfactants for steamflooding, surfactant enhanced oil recovery, and process applications. The CMC's and solution behavior of commercial surfactants as a function o...

L. A. Noll

1989-01-01

270

Fat Emulsions for Injection  

MedlinePLUS

Your doctor has ordered fat emulsion to be used as a source of calories and fatty acids to maintain or increase your weight. The medication ... Before you administer fat emulsion, look at the solution closely. It should be free of floating material. Gently squeeze the bag or observe ...

271

Rheology of double emulsions  

Microsoft Academic Search

New equations for the viscosity of concentrated double emulsions of core–shell droplets are developed using a differential scheme. The equations developed in the paper predict the relative viscosity (?r) of double emulsions to be a function of five variables: a\\/b (ratio of core drop radius to shell outer radius), ?21 (ratio of shell liquid viscosity to external continuous phase viscosity),

Rajinder Pal

2007-01-01

272

HEAT-SET WHEY PROTEIN EMULSION GELS: ROLE OF ACTIVE AND INACTIVE FILLER PARTICLES  

Microsoft Academic Search

Viscoelastic properties of heat-set whey protein emulsion gels containing active filler (protein-covered droplets) and inactive filler (surfactant-covered droplets) have been investigated at small and large deformations using a controlled stress rheometer. Data are reported as a function of protein concentration, oil volume fraction, and average emulsion droplet size. The active filler enhances the gel strength, whereas the inactive filler reduces

Eric Dickinson; Jianshe Chen

1999-01-01

273

Mechanical Properties and Microstructure of Heat-set Whey Protein Emulsion Gels: Effect of Emulsifiers  

Microsoft Academic Search

A comparison of the viscoelastic properties of heat-set whey protein-stabilized oil-in-water emulsion gels in the presence and absence of added emulsifier has been complemented by structural information from confocal laser scanning microscopy (CLSM). Emulsions (300 mL\\/L triolein oil, pH 7.0) were prepared with pure ? -lactoglobulin (8 g\\/kg) or water-soluble surfactant (20 g\\/kg Tween 20) as emulsifier and commercial whey

Jianshe Chen; Eric Dickinson; Maud Langton; Anne-Marie Hermansson

2000-01-01

274

Mechanochemistry and Processing Characteristics of Aqueous Emulsions of High-Viscosity Petroleum Products  

Microsoft Academic Search

The effect of mechanochemical treatment on the emulsification of high-viscosity petroleum products is reported. Thermally stable water-in-oil emulsions, whose viscosity is five times lower than the viscosity of the original petroleum product, are prepared for the first time by mechanochemical treatment in the presence of a surfactant. The critical fluxing temperature, thermal properties, and viscosity of asphalt emulsions prepared by

N. I. Red'kina; G. S. Khodakov

2002-01-01

275

Encapsulation of Pigment Red 122 into UV-curable resins via a mini-emulsion technique  

Microsoft Academic Search

Purpose – The purpose of this paper is to encapsulate aqueous dispersions of nano-scale CI Pigment Red 122 prepared through ball milling into UV-curable resins, 1,6 hexanediol diacrylate (HDDA, monomer), and polyester acrylate (oligomer) using the mini-emulsion technique. Design\\/methodology\\/approach – The encapsulation of pigment is achieved by mixing a surfactant-stabilised pigment dispersions and a monomer\\/oligomer mini-emulsions and subjecting both to

O. A. Hakeim; Qinguo Fan; Yong K. Kim

2010-01-01

276

Synthesis of emulsion-templated porous polyacrylonitrile and its pyrolysis to porous carbon monoliths  

Microsoft Academic Search

PolyHIPEs are emulsion-templated polymers synthesized within high internal phase emulsions (HIPEs). The miscibility of acrylonitrile (AN) with water has made it difficult to synthesize PAN-based polyHIPEs. This paper describes the successful synthesis of PAN-based polyHIPEs by crosslinking through copolymerization with divinylbenzene (DVB), by stabilization with a polyglycerol polyricinoleate surfactant, and by initiation with both oil- and water-soluble initiators. The PAN-based

Noa Cohen; Michael S. Silverstein

2011-01-01

277

Transport of ions through the oil phase of W 1\\/O\\/W 2 double emulsions  

Microsoft Academic Search

Using a capillary video microscopy technique, the ion transport at liquid–liquid interfaces and through a surfactant-containing emulsion liquid membrane was visually studied by preparing a double emulsion globule within the confined space of a thin-walled, transparent, cylindrical microtube. NaCl and AgNO3 were selected as the model reactants and were prepared to form a NaCl\\/AgNO3 pair across the oil film. By

Jing Cheng; Jian-Feng Chen; Min Zhao; Qing Luo; Li-Xiong Wen; Kyriakos D. Papadopoulos

2007-01-01

278

Breakup of bubbles and drops in steadily sheared foams and concentrated emulsions.  

PubMed

This experimental study is focused on the process of bubble breakup in steadily sheared foams, at constant shear rate or constant shear stress. Two different types of surfactants were used and glycerol was added to the aqueous phase, to check how the bubble breakup depends on the surface modulus and on bulk viscosity of the foaming solutions. The experiments show that bubble breakup in foams occurs above a well defined critical dimensionless stress, tau[over]CR identical with(tauCRR/sigma) approximately 0.40, which is independent of surfactant used, solution viscosity, and bubble volume fraction (varied between 92 and 98%). Here tauCR is the dimensional shear stress, above which a bubble with radius R and surface tension sigma would break in sheared foam. The value of the critical stress experimentally found by us tau[over]CR approximately 0.40, is about two orders of magnitude lower than the critical stress for breakup of single bubbles in sheared Newtonian liquids, tau[over]CR approximately 25. This large difference in the critical stress is explained by the strong interaction between neighboring bubbles in densely populated foams, which facilitates bubble subdivision into smaller bubbles. A strong effect of bubble polydispersity on the kinetics of bubble breakup (at similar mean bubble size) was observed and explained. Experiments were also performed with hexadecane-in-water emulsions of drop volume fraction 83%emulsions. Qualitatively similar behavior was observed to that of foams, with the critical dimensionless stress for drop breakup being lower, tau[over]CR approximately 0.15, and practically independent of the drop volume fraction and viscosity ratio (varied between 0.01 and 1). This critical stress is by several times lower than the critical stress for breakage of single drops in sheared Newtonian fluids at comparable viscosity ratio, which evidences for facilitated drop subdivision in concentrated emulsions. To explain the measured low values of the critical stress, a different type of capillary instability of the breaking bubbles and drops in concentrated foams and emulsions is proposed and discussed. PMID:19113128

Golemanov, K; Tcholakova, S; Denkov, N D; Ananthapadmanabhan, K P; Lips, A

2008-11-24

279

Droplet-based microfluidics and the dynamics of emulsions  

NASA Astrophysics Data System (ADS)

Emulsions are complex fluids already involved for a long time in a wide-range of industrial processes, such as, for example, food, cosmetics or materials synthesis [1]. More recently, applications of emulsions have been extended to new fields like biotechnology or biochemistry where the compartmentalization of compounds in emulsion droplets is used to parallelise (bio-) chemical reactions [2]. Interestingly, these applications pinpoint to fundamental questions dealing with surfactant dynamics, dynamic surface tension, hydrodynamic interactions and electrohydrodynamics. Droplet-based microfluidics is a very powerful tool to quantitatively study the dynamics of emulsions at the single droplet level or even at the single interface level: well-controlled emulsions are produced and manipulated using hydrodynamics, electrical forces, optical actuation and combination of these effects. We will describe here how droplet-based microfluidics is used to extract quantitative informations on the physical-chemistry of emulsions for a better understanding and control of the dynamics of these systems [3].[4pt] [1] J. Bibette et al. Rep. Prog. Phys., 62, 969-1033 (1999)[0pt] [2] A. Theberge et al., Angewandte Chemie Int. Ed. 49, 5846 (2010)[0pt] [3] J.-C. Baret et al., Langmuir, 25, 6088 (2009)

Baret, Jean-Christophe; Brosseau, Quentin; Semin, Benoit; Qu, Xiaopeng

2012-02-01

280

Design and development of multiple emulsion for enhancement of oral bioavailability of acyclovir.  

PubMed

The objective of this investigation was to design and develop water-in-oil-in-water type multiple emulsions (w/o/w emulsions) entrapping acyclovir for improving its oral bioavailability. Multiple emulsions (MEs) were prepared and optimized using Span-80 and Span-83 as lipophilic surfactant and Brij-35 as hydrophilic surfactant. The physio-chemical properties of the w/o/w emulsions - particle size, viscosity, phase separation (centrifugation test) and entrapment efficiency were measured and evaluated along with macroscopic and microscopic observations to confirm multiple nature, homogeneity and globule size. Stability study, in vitro and ex vivo release studies were performed followed by in vivo studies in rats. Stable w/o/w emulsions with a particle size of 33.098 ± 2.985 µm and 85.25 ± 4.865% entrapment efficiency were obtained. Stability studies showed that the concentration of lipophilic surfactant was very important for stability of MEs. Drug release from the prepared formulations showed initial rapid release followed by a much slower release. In vivo studies in rats indicated prolonged release and better oral bioavailability as compared to drug solution. The overall results of this study show the potential of the w/o/w emulsions as promising drug delivery systems for acyclovir. PMID:23281917

Paul, Sumita; Kumar, Abhinesh; Yedurkar, Pramod; Sawant, Krutika

2013-01-02

281

Preparation of finely dispersed O/W emulsion from fatty acid solubilized in subcritical water.  

PubMed

A novel method for preparing a finely dispersed oil-in-water emulsion is proposed. Octanoic acid dissolved in water at a high temperature of 220 or 230 degrees C at 15 MPa was combined with an aqueous solution of a surfactant and then the mixture was cooled. When a nonionic surfactant, decaglycerol monolaurate (ML-750) or polyoxyethylene sorbitan monolaurate (Tween 20), was used, fine emulsions with a median oil droplet diameter of 100 nm or less were successfully prepared at ML-750 and Tween 20 concentrations of 0.083% (w/v) and 0.042%, respectively, or higher. The diameters were much smaller than those of oil droplets prepared by the conventional homogenization method using a rotor/stator homogenizer. However, an anionic surfactant, sodium dodecyl sulfate, was not adequate for the preparation of such fine emulsions by the proposed method. Although the interfacial tensions between octanoic acid and the surfactant solutions were measured at different temperatures, they were not an indication for selecting a surfactant for the successful preparation of the fine emulsion by the proposed method. PMID:15313654

Khuwijitjaru, Pramote; Kimura, Yukitaka; Matsuno, Ryuichi; Adachi, Shuji

2004-10-01

282

Favorable Attributes of Alkaline-Surfactant-Polymer Flooding  

Microsoft Academic Search

Summary A laboratory study of the alkaline-surfactant-polymer (ASP) pro- cess was conducted. It was found from phase-behavior studies that for a given synthetic surfactant and crude oil containing naph- thenic acids, optimal salinity depends only on the ratio of the moles of soap formed from the acids to the moles of synthetic surfactant present. Adsorption of anionic surfactants on carbonate

Shunhua Liu; Danhua Leslie Zhang; Wei Yan; Maura Puerto; George Hirasaki; Clarence Miller

2008-01-01

283

Polyoxyethylenated dodcylphenol for breaking up water in oil emulsions  

Microsoft Academic Search

Polyethylene glycol (PEG) of different molecular weights, namely, 200, 400, 600 and 1,000 g\\/mol was reacted with dodecyl phenol\\u000a to form compounds having different hydrophile-lipophile balances and hence different surface activities. The demulsification\\u000a efficiency of the prepared surfactants in breaking up water-in-crude oil emulsions was evaluated. The data revealed that demulsification\\u000a efficiency increases with increasing demulsifier concentration, contact time and

Nehal S. Ahmed; Amal M. Nassar

2001-01-01

284

Preparation of polystyrene latex particles by gamma-rays-induced emulsifier-free emulsion polymerization  

Microsoft Academic Search

Monodisperse polystyrene latex particles were prepared by 60Co-gamma-ray radiation-induced emulsifier-free emulsion polymerization with the use of surfactant monomer at room temperature. The surfactant monomer 10(9)-hydroxyl-9(10)-allyl ether octadecanoic acid (HAEOA) was synthesized and characterized by FT-IR and 1H-NMR spectra. TEM was used to characterize the polystyrene latex particles. HAEOA acted as not only a comonomer but also a stabilizer to copolymerize

Xinbo Wang; Zhicheng Zhang

2006-01-01

285

Edge-modified amphiphilic Laponite nano-discs for stabilizing Pickering emulsions.  

PubMed

We investigated the effect of amphiphilic Laponite nano-discs, which were edge-modified by hydrophobic chains, on the properties of Pickering emulsions and Pickering emulsions polymerization. Comparing to unmodified Laponites, these amphiphilic nano-discs can greatly reduce the surface tension, resulting in very stable Pickering emulsions. These particles uniquely combine the Pickering effect with amphiphilic properties similar to the surfactant. Taking advantage of these amphiphilic Pickering emulsifiers, miniemulsion polymerization of styrene was performed. Homogeneous polystyrene nanoparticles with size around 150nm could thus be prepared. PMID:23998369

Yang, Ying; Liu, Zhi; Wu, Dayong; Wu, Man; Tian, Ye; Niu, Zhongwei; Huang, Yong

2013-08-14

286

Demulsification of a crude oil middle phase emulsion  

SciTech Connect

The middle phase emulsion of a crude oil emulsion produced by a surfactant flooding of an oil reservoir is demulsified by contacting it with a water-soluble alkali metal hydroxide in an amount and under conditions sufficient to cause the hydrolysis of the middle phase emulsion and its subsequent separation into phases, wherein one of the phases is primarily an oil phase. The oil phase is then separated and, thereafter, can be further demulsified by demetalizing the oil by contacting it with a carboxylic acid or an amine salt of a carboxylic acid. It may be desirable to concurrently or subsequently treat the oil with an organic base, which can also be an amine demulsifier, to obtain a pH of from about 7 to about 9 in the final oil phase recovered from the acid demetalization step.

Duke, R.B.

1984-03-27

287

Cyclodextrins as stabilizers for the preparation of drug nanocrystals by the emulsion solvent diffusion method.  

PubMed

Cyclodextrins (CyDs) were employed as protective stabilizers for the preparation of surfactant-free nanocrystals of indomethacin (IMC) by using the emulsion solvent diffusion method. The effect of changing the type and concentration of CyDs on the formation of IMC nanocrystals was investigated. Dispersions were freeze-dried to characterize the size, shape, nanoparticle yield, crystallinity, and dissolution behavior of the obtained particles. Submicron-sized particles of IMC with average diameters in the range of 300-500 nm were obtained by incorporating alpha-, beta-, or gamma-CyD in the outer phase of the primary emulsions. Quantitative determination demonstrated that more than 80% of IMC was recovered as fine particles smaller than 0.8 microm. The powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) analyses of the freeze-dried samples confirmed the polymorphic change of IMC to the meta-stable form. A significant enhancement in the dissolution rate of IMC nanocrystals was observed when compared to the commercial powder. PMID:18325698

Makhlof, Abdallah; Miyazaki, Yuta; Tozuka, Yuichi; Takeuchi, Hirofumi

2008-01-20

288

Studies of water-continuous emulsions of heavy crude oils prepared by alkali treatment  

SciTech Connect

Pumping of heavy crudes as concentrated oil-in-water (O/W) emulsions may be a feasible pipeline transport scheme for viscous crudes. Many crude oils can be emulsified by treatment with alkali without the addition of expensive surfactants. In experimental studies of seven crudes, stable emulsions could be formed with four by alkali treatment; two could not be emulsified; and one formed unstable emulsions. High shear viscosity, particle size, and stability measurements on 60% emulsions formed with various amounts of alkali are reported. High shear viscosities below 100 mPa . s (100 cp) at 25/sup 0/C (77/sup 0/F) indicate that concentrated emulsions of some crudes can be transported in pipelines at concentrations of 60% and higher.

Plegue, T.H.; Frank, S.G.; Zakin, J.L.; Fruman, D.H.

1989-05-01

289

Sensory evaluation of sodium chloride-containing water-in-oil emulsions.  

PubMed

The sensory perception of water-in-oil emulsions containing a saline-dispersed aqueous phase was investigated. Manipulating saltiness perception was achieved by varying the mass fraction aqueous phase (MFAP), initial salt load, and surfactant concentration [(polyglycerol polyricinoleate (PgPr)] of the emulsions, with formulations based on a central composite design. Saltiness and emulsion thickness were evaluated using a trained sensory panel, and collected data were analyzed using response surface analysis. Emulsion MFAP was the most important factor correlated with increased salt taste intensity. Emulsifier concentration and interactions between NaCl and PgPr had only minor effects. Emulsions more prone to destabilization were perceived as saltier irrespective of their initial salt load. The knowledge gained from this study provides a powerful tool for the development of novel sodium-reduced liquid-processed foods. PMID:22463684

Rietberg, Matthew R; Rousseau, Dérick; Duizer, Lisa

2012-04-13

290

Emulsion forming drug delivery system for lipophilic drugs.  

PubMed

In the recent years, there is a growing interest in the lipid-based formulations for delivery of lipophilic drugs. Due to their potential as therapeutic agents, preferably these lipid soluble drugs are incorporated into inert lipid carriers such as oils, surfactant dispersions, emulsions, liposomes etc. Among them, emulsion forming drug delivery systems appear to be a unique and industrially feasible approach to overcome the problem of low oral bioavailability associated with the BCS class II drugs. Self-emulsifying formulations are ideally isotropic mixtures of oils, surfactants and co-solvents that emulsify to form fine oil in water emulsions when introduced in aqueous media. Fine oil droplets would pass rapidly from stomach and promote wide distribution of drug throughout the GI tract, thereby overcome the slow dissolution step typically observed with solid dosage forms. Recent advances in drug carrier technologies have promulgated the development of novel drug carriers such as control release self-emulsifying pellets, microspheres, tablets, capsules etc. that have boosted the use of "self-emulsification" in drug delivery. This article reviews the different types of formulations and excipients used in emulsion forming drug delivery system to enhance the bioavailability of lipophilic drugs. PMID:22568032

Wadhwa, Jyoti; Nair, Anroop; Kumria, Rachna

291

Behavior of Surfactant Mixtures at Solid/Liquid and Oil/Liquid Interfaces in Chemical Flooding Systems. Semiannual Technical Progress Report from September 01, 2002.  

National Technical Information Service (NTIS)

The aim of the project is to develop a knowledge base to help with the design of enhanced process for mobilizing and extracting untrapped oil. We emphasize on evaluating novel surfactant mixtures and on obtaining optimum combinations of the surfactants in...

P. Somasundaran

2003-01-01

292

DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS  

SciTech Connect

There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior, interfacial tension (IFT) and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases IFT with a minimum at about 0.2 M. Addition of surfactant decreases IFT further. In the absence of surfactant the minerals are oil-wet after aging with crude oil. Addition of surfactant solution decreases the contact angle to intermediate-wet for many surfactants and water-wet for one surfactant. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Plans for the next quarter include conducting core adsorption, phase behavior, wettability and mobilization studies.

Kishore K. Mohanty

2003-07-01

293

Preparation and physical characterization of a novel marine oil emulsion as a potential new formulation vehicle for lipid soluble drugs.  

PubMed

Emulsions often contain vegetable oils such as soybean oil. In this study, a 10% (w/w) of marine mammal oil emulsion was prepared. The effect of a group of emulsifying agents on the stability of the 10% of seal oil emulsion was examined. The emulsifying agents studied were hydrogenated castor oil coated with various polyoxyethylene derivatives. It was found that 2.5% of HCO-40 resulted in the most stable seal oil emulsion. The size of the emulsified droplets defined by their diameters was found to be around 240-270 nm. The initial zeta-potential and pH value of the emulsion were found to be around -27 mV and 3.5, respectively, which decreased over time, to about -31 mV and 2.4, respectively. This is believed to be a result of the hydrolysis of triacylglycerides into free fatty acids in the emulsion. The effect of various amounts of Crodasinic LS-30, a negatively charged surfactant, and Incroqal Behenyl TMS, a positively charged surfactant, on the emulsion was investigated. It was shown that Crodasinic LS-30 had very little effect on the particle size, zeta-potential and pH, while the effect of Incroquat Benhenyl TMS was found to be dependent upon the concentration of the surfactant used. PMID:16901663

Cui, Guohui; Wang, Lili; Davis, Philip J; Kara, Mohameditaki; Liu, Hu

2006-06-29

294

Partitioning behavior of an acid-cleavable, 1,3-dioxolane alkyl ethoxylate, surfactant in single and binary surfactant mixtures for 2- and 3-phase microemulsion systems according to ethoxylate head group size  

SciTech Connect

Partition coefficients for a pH-degradable 1,3-dioxolane alkyl ethoxylate surfactant, 4-CH{sub 3}O (CH{sub 2}CH{sub 2}O){sub 5.6}-CH{sub 2}, 2,2-(CH{sub 2}){sub 12}CH{sub 3}, 2-(CH{sub 2}) CH{sub 3}, 1,3-dioxolane or ''cyclic ketal'' surfactant, CK-2,13-E{sub 5.6,ave}, between isooctane- and water-rich phases of 2- and 3-phase microemulsion systems (K{sub n}) were determined as functions of the ethoxylate size, n, and temperature for the neat surfactant and its binary surfactant mixtures, to understand the partitioning of alkyl ethoxylates possessing a broad distribution of ethoxylate size and to determine conditions required for formation of 3-phase microemulsion systems at an optimal temperature where phase separation occurs rapidly, important for protein purification via proteins selective partitioning to the middle phase, driven by affinity to the second surfactant of the binary mixture. A semi-empirical thermodynamic mathematical model described the partitioning data well, provided optimal temperature values consistent with phase diagrams and theory, and demonstrated that the tail region of CK-2,13-E{sub 5.6,ave} is more polar than the hydrophobes of fatty alcohol ethoxylates. The addition of Aerosol-OT (AOT) removed the temperature sensitivity of CK-2,13-E{sub 5.6,ave}s partitioning, producing 3-phase microemulsion systems between 20 C and 40 C. Analysis of the bottom phases of the 2- and 3-phase microemulsion systems formed by CK-2,13-E{sub 5.6,ave} via small-angle neutron scattering demonstrated the presence of spherical, monodisperse oil-in-water microemulsions.

Gomez Del Rio, Javier A [ORNL; Hayes, Douglas G [ORNL; Urban, Volker S [ORNL

2010-01-01

295

Studies on extraction of chromium (VI) from acidic solutions containing various metal ions by emulsion liquid membrane using Alamine 336 as extractant  

Microsoft Academic Search

The extraction of chromium (VI) ions from acidic solutions containing various metal ions by emulsion liquid membrane (ELM) was studied. Liquid membrane consists of a diluent, a surfactant, and an extractant. 0.5M ammonium carbonate solution was used as stripping solution. Effects of acid concentration in feed solution, type and concentration of stripping solution, mixing speed, surfactant concentration, phase ratio and

Recep Ali Kumbasar

2008-01-01

296

Photophysical Behavior of 8-Anilino-1-Naphthalenesulfonate in Vesicles of Pulmonary Surfactant Dipalmitoylphosphatidylcholine (DPPC) and Its Sensitivity toward the Bile Salt-Vesicle Interaction.  

PubMed

The photophysical behavior of 8-anilino-1-naphthalenesulphonate (ANS) in vesicles of dipalmitoylphosphatidylcholine (DPPC), a pulmonary surfactant, has been carried out in a detailed manner. ANS shows notable variations in fluorescence intensity, lifetime, and anisotropy parameters as it gets into the vesicle. It was found that ANS partitions well into the DPPC bilayer membrane with an estimated partition coefficient of ?2.0 × 10(5). Among the various fluorescence parameters of ANS, fluorescence anisotropy was found to be most responsive to the temperature induced phase change of the bilayer membrane. These interesting fluorescence parameters of ANS were then used to study the hydration of lipid bilayer membrane by submicellar concentration of bile salts. From the steady-state fluorescence intensity and dynamic fluorescence lifetime analyses it is clear that ANS is able to probe the submicellar concentration (?1 mM) of bile salt induced hydration of lipid bilayer membrane that accompanies expulsion of ANS from the bilayer to the aqueous bulk phase. Lower-temperature shift in the phase transition of DPPC bilayer indicates that fluorescence anisotropy of ANS is sensitive enough to the bile salt induced perturbation in the packed acyl chains of DPPC bilayer and modification in the membrane fluidity. In presence of sodium deoxycholate (NaDC) and sodium cholate (NaC) in DPPC vesicles, ANS experiences restriction in rotational mobility which is evident from the variation in steady-state fluorescence anisotropy and fluorescence anisotropy decay parameters. PMID:23930911

Mohapatra, Monalisa; Mishra, Ashok K

2013-08-26

297

[Effects of sub-micro emulsion composition on cellular disposition of incorporated lipophilic drug].  

PubMed

Objective: To investigate the effects of sub-micro emulsion composition on cellular uptake and disposition of incorporated lipophilic drug. Methods: Sub-micro emulsions containing 10 % oil, 1.2 % lecithin and 2.25 % glycerol were prepared, and the fluorescent agent coumarin 6 was used as a model drug. The effects of oil types, co-surfactants and cationic lipid on uptake and elimination kinetics of 6-coumarin in HeLa cells were studied. The uptake mechanism of sub-micro emulsions was further investigated. Results: Oil type and Tweens had no influence on the cellular uptake. Modifications of surfactants with Span series increased the cellular influx, among which Span 20 with hydrophilic-lipophilic balance (HLB) value of 8.6 was the best enhancer. The intracellular drug level reached up to (46.09 ±1.98)ng/?g protein which had significant difference with control group [(38.54 ±0.34)ng/?g protein]. The positively charged emulsions significantly increased the uptake rate constant and elimination rate constant which were 4 times and 1.5 times of those in anionic groups, respectively. The uptake enhancement was also observed in cationic emulsions, cellular concentrations at plateau were (42.73 ±0.84)ng/?g protein, which was about 3 times of that in anionic emulsions [(15.71 ±0.74)ng/?g protein], when extracellular drug concentration kept at 100 ng/ml. Cationic emulsions delivered the payload mainly by direct drug transfer to contacted cells, while the negative ones depended on both drug passive diffusion and clathrin-mediated endocytosis of drug containing oil droplets which accounted for 20% of the intracellular drug. Conclusion: Interfacial characteristic of sub-micro emulsions such as co-surfactants HLB as well as zeta potentials can influence lipophilic drug both in cellular uptake and elimination. PMID:24167133

Sun, Xiao-Yi; Xiang, Zhi-Qiang; Wu, Shuo; Lv, Yuan-Yuan; Liang, Wen-Quan

2013-09-01

298

Influence of phase inversion on the formation and stability of one-step multiple emulsions.  

PubMed

A novel method of preparation of water-in-oil-in-micelle-containing water (W/O/W(m)) multiple emulsions using the one-step emulsification method is reported. These multiple emulsions were normal (not temporary) and stable over a 60 day test period. Previously, reported multiple emulsion by the one-step method were abnormal systems that formed at the inversion point of simple emulsion (where there is an incompatibility in the Ostwald and Bancroft theories, and typically these are O/W/O systems). Pseudoternary phase diagrams and bidimensional process-composition (phase inversion) maps were constructed to assist in process and composition optimization. The surfactants used were PEG40 hydrogenated castor oil and sorbitan oleate, and mineral and vegetables oils were investigated. Physicochemical characterization studies showed experimentally, for the first time, the significance of the ultralow surface tension point on multiple emulsion formation by one-step via phase inversion processes. Although the significance of ultralow surface tension has been speculated previously, to the best of our knowledge, this is the first experimental confirmation. The multiple emulsion system reported here was dependent not only upon the emulsification temperature, but also upon the component ratios, therefore both the emulsion phase inversion and the phase inversion temperature were considered to fully explain their formation. Accordingly, it is hypothesized that the formation of these normal multiple emulsions is not a result of a temporary incompatibility (at the inversion point) during simple emulsion preparation, as previously reported. Rather, these normal W/O/W(m) emulsions are a result of the simultaneous occurrence of catastrophic and transitional phase inversion processes. The formation of the primary emulsions (W/O) is in accordance with the Ostwald theory ,and the formation of the multiple emulsions (W/O/W(m)) is in agreement with the Bancroft theory. PMID:19441778

Morais, Jacqueline M; Rocha-Filho, Pedro A; Burgess, Diane J

2009-07-21

299

Combined and Independent Action of Proteins SP-B and SP-C in the Surface Behavior and Mechanical Stability of Pulmonary Surfactant Films  

PubMed Central

The hydrophobic proteins SP-B and SP-C are essential for pulmonary surfactant function, even though they are a relatively minor component (<2% of surfactant dry mass). Despite countless studies, their specific differential action and their possible concerted role to optimize the surface properties of surfactant films have not been completely elucidated. Under conditions kept as physiologically relevant as possible, we tested the surface activity and mechanical stability of several surfactant films of varying protein composition in vitro using a captive bubble surfactometer and a novel (to our knowledge) stability test. We found that in the naturally derived surfactant lipid mixtures, surfactant protein SP-B promoted film formation and reextension to lower surface tensions than SP-C, and in particular played a vital role in sustaining film stability at the most compressed states, whereas SP-C produced no stabilization. Preparations containing both proteins together revealed a slight combined effect in enhancing film formation. These results provide a qualitative and quantitative framework for the development of future synthetic therapeutic surfactants, and illustrate the crucial need to include SP-B or an efficient SP-B analog for optimal function.

Schurch, David; Ospina, Olga L.; Cruz, Antonio; Perez-Gil, Jesus

2010-01-01

300

Effects of isomeric alcohols on the phase behavior and solubilization of the microemulsion systems formed by anionic surfactants  

Microsoft Academic Search

The middle-phase ?-? fishlike phase diagrams of the pseudoquaternary microemulsion systems sodium dodecyl sulfate (sodium\\u000a dodecyl sulfonate, sodium dodecyl benzene sulfonate)\\/1-butanol (2-butanol, t-butanol)\\/n-octane\\/brine (5% NaCl) were plotted. The effect of three isomeric alcohols (1-butanol, 2-butanol, and t-butanol) on the phase behavior and solubilization was investigated. From the ?-? fishlike phase diagram, the composition\\u000a of the interfacial layer, the solubilities of

Zai-Mei Zhang; Jin-Ling Chai; Yan Li; Xiao-Nan Xue; Jian-Jun Lu

2010-01-01

301

Freeze-thaw stability of water-in-oil emulsions.  

PubMed

Factors influencing water-in-oil emulsion stability during freeze/thaw-cycling, namely interfacial crystallization vs. network crystallization and the sequence of crystallization events (i.e., dispersed vs. continuous phase or vice versa), are assessed. We show that destabilization is most apparent with a liquid-state emulsifier and a continuous oil phase that solidifies prior to the dispersed phase. Emulsions stable to F/T-cycling are obtained when the emulsifier crystallizes at the oil-water interface or in emulsions where the continuous phase crystallizes after the dispersed aqueous phase. The materials used are two food-grade oil-soluble emulsifiers - polyglycerol polyricinoleate (PGPR) and glycerol monostearin (GMS) and two continuous oil phases with differing crystallization temperatures - canola oil and coconut oil. Emulsion stability is assessed with pulsed field gradient NMR droplet size analysis, sedimentation, microscopy and differential scanning calorimetry. This study demonstrates the sequence of crystallization events and the physical state of the surfactant at the oil-water interface strongly impact the freeze-thaw stability of water-in-oil emulsions. PMID:19683718

Ghosh, S; Rousseau, D

2009-07-25

302

Influence of the Speed Mixing-on Viscosity and Droplet Size of Oil in Water Emulsions  

Microsoft Academic Search

The viscosity and droplet size of oil in water emulsions prepared at different speed of mixing have been measured. Nonionic surfactant dissolved in fresh water has been used to emulsify the crude oil vacuum distillation residues from the Mexican petroleum refineries by mean of a dynamic mixer in batches of 600 mL. The aim of the present research was to reduce

María Vita Peralta-Martínez; Alejandro Arriola-Medellín; Emilio Manzanares-Papayanopoulos; Ramón Sánchez-Sánchez; Elvia María Palacios-Lozano

2004-01-01

303

Effect of some cationic detergents on an oil\\/water emulsion stabilized by sodium lauryl sulphate  

Microsoft Academic Search

A petroleum ether-in-water emulsion stabilized by sodium lauryl sulphate, an anionic surfactant was studied and its stability has been examined in the light of D. L. V. O. theory by adding some cationic detergents with different carbon chain lengths and head groups size. Flocculation studies were made haemocytometrically and the values were correlated with zeta potentials which were determined microelectro

P. Babadur; S. N. Srivastava

1975-01-01

304

Kinetics of emulsion copolymerization of (2-methacryloyloxyethyl) trimethyl ammonium chloride and acrylamide with gamma rays  

Microsoft Academic Search

Inverse emulsion copolymerization of (2-methacryloyloxyethyl) trimethyl ammonium chloride with acrylamide has been studied with gamma ray dilatometrically. Aqueous monomer solutions were emulsified in kerosene with a blend of two surfactants (Span80 and OP10). The gel effect is evident from the increase of the molecular weight with conversion and also from the percentage conversion versus time curves. Monomer reactivity ratios have

Ge Xuewu; Ye Qiang; Xu Xiangling; Zhang Zhicheng; Sun Qian

1997-01-01

305

A new double emulsion solvent diffusion technique for encapsulating hydrophilic molecules in PLGA nanoparticles  

Microsoft Academic Search

The commonly utilized techniques for encapsulating hydrophilic molecules in NP suffer from low encapsulation efficiency because of the drug rapid partitioning to the external aqueous phase. We hypothesized that combining the double emulsion system with a partially water-soluble organic solvent, could result in better encapsulation yield of hydrophilic molecules in nano-sized NP, and the utilization of both biocompatible surfactants and

Einat Cohen-Sela; Michael Chorny; Nickolay Koroukhov; Haim D. Danenberg; Gershon Golomb

2009-01-01

306

Surfactants and interfacial phenomena, 2nd Ed  

SciTech Connect

The second edition of this monograph on surfactants has been updated to reflect recent advances in our knowledge of theory and practices. New applications run the gamut from microelectronics and magnetic recording, to biotechnology and nonconventional energy conversion. There is a new chapter on the interactions between surfactants. New sections have been added, and original sections expanded, on such topics as ultralow liquid-liquid interfacial tension; microemulsions, miniemulsions, and multiple emulsions; liquid crystal formation; hydrotropy; and steric forces in the stabilization of dispersions. There is also new material on lime soap dispersing agents; fabric softeners, adsorption and wetting of solid surfaces, both equilibrium and none-equilibrium; the relationship between adsorption and micellation in aqueous solutions and its effect on surface tension reduction; and factors determining micellar structure and shape.

Rosen

1989-01-01

307

Porous biomaterials obtained using supercritical CO 2- water emulsions.  

PubMed

Highly porous, hydrophilic porous matrices were fabricated by using a high internal phase supercritical-CO2 (scCO2) emulsion templating technique. The novel aspect of the work resides in the combination of a natural biopolymer (dextran) as the building component of the matrices and of an environmentally benign solvent (supercritical-CO2) as the pore-generating phase. The synthetic route to the porous biomaterials involved the preliminary functionalization of the dextran chains with methacrylic moieties, formation of a scCO2-in-water concentrated emulsion, and curing of the external phase of the emulsion by radical polymerization. As the emulsion stabilizer a perfluoropolyether surfactant was chosen. The matrices obtained exhibit highly interconnected, trabecular morphologies. The porous biomaterial morphologies were qualitatively characterized by scanning electron microscopy (SEM) and the evaluation of void and interconnect sizes was carried out on the micrographs taken with the light microscope. To tailor the morphologies of the porous structures, the influence of the volume fraction of the internal phase and of the surfactant/internal phase ratio was investigated. It was established that the variation of the volume fraction of the internal phase exerted only a limited influence on void and interconnect sizes. On the contrary the increase of surfactant concentration alters dramatically the distribution of void size, a large proportion of the void space enclosed within the matrix being attributable to voids with a diameter exceeding 100 microm. The free toxic solvent process of fabrication of the porous structures, the high water content, the expected biocompatibility, and the mechanical properties that resemble natural tissues make these porous hydrogels potentially useful for tissue engineering applications. PMID:17590033

Palocci, Cleofe; Barbetta, Andrea; La Grotta, Angelo; Dentini, Mariella

2007-06-23

308

Thermodynamically Stable Pickering Emulsions  

NASA Astrophysics Data System (ADS)

We show that under appropriate conditions, mixtures of oil, water, and nanoparticles form thermodynamically stable oil-in-water emulsions with monodisperse droplet diameters in the range of 30 150 nm. This observation challenges current wisdom that so-called Pickering emulsions are at most metastable and points to a new class of mesoscopic equilibrium structures. Thermodynamic stability is demonstrated by the spontaneous evolution of binary droplet mixtures towards one intermediate size distribution. Equilibrium interfacial curvature due to an asymmetric charge distribution induced by adsorbed colloids explains the growth of emulsion droplets upon salt addition. Moreover, the existence of a minimal radius of curvature with a concomitant expulsion of excess oil is in close analogy with microemulsions.

Sacanna, S.; Kegel, W. K.; Philipse, A. P.

2007-04-01

309

Thermodynamically stable pickering emulsions.  

PubMed

We show that under appropriate conditions, mixtures of oil, water, and nanoparticles form thermodynamically stable oil-in-water emulsions with monodisperse droplet diameters in the range of 30-150 nm. This observation challenges current wisdom that so-called Pickering emulsions are at most metastable and points to a new class of mesoscopic equilibrium structures. Thermodynamic stability is demonstrated by the spontaneous evolution of binary droplet mixtures towards one intermediate size distribution. Equilibrium interfacial curvature due to an asymmetric charge distribution induced by adsorbed colloids explains the growth of emulsion droplets upon salt addition. Moreover, the existence of a minimal radius of curvature with a concomitant expulsion of excess oil is in close analogy with microemulsions. PMID:17501389

Sacanna, S; Kegel, W K; Philipse, A P

2007-04-12

310

Adsorption of Gemini surfactants onto clathrate hydrates.  

PubMed

This work addresses the adsorption of two Gemini surfactants at the cyclopentane (CP) hydrate-water interface. The Gemini surfactants investigated here are Dowfax C6L and Dowfax 2A1 that have two anionic head groups and one hydrophobic tail group. The adsorption of these surfactants was quantified using adsorption isotherms and the adsorption isotherms were determined using liquid-liquid titrations. Even if the Gemini surfactant adsorption isotherms show multi-layer adsorption, they possess the first Langmuir layer with the second adsorption layer only evident in the 2A1 adsorption isotherm. Zeta potentials of CP hydrate particles in the surfactant solution of various concentrations of Dowfax C6L and Dowfax 2A1 were measured to further explain their adsorption behavior at the CP hydrate-water interface. Zeta potentials of alumina particles as a model particle system in different concentrations of sodium dodecyl sulfate (SDS), Dowfax C6L and Dowfax 2A1 were also measured to confirm the configuration of all the surfactants at the interface. The determination of the isotherms and zeta-potentials provides an understanding framework for the adsorption behavior of the two Gemini surfactants at the hydrate-water interface. PMID:24144366

Salako, O; Lo, C; Couzis, A; Somasundaran, P; Lee, J W

2013-09-17

311

Selective extraction of chromium (VI) from multicomponent acidic solutions by emulsion liquid membranes using tributhylphosphate as carrier  

Microsoft Academic Search

The facilitated extraction of Cr(VI) through an emulsion liquid membrane (ELM) was investigated, using tributyl phosphate (TBP) as mobile carrier. The emulsion liquid membrane phase consists of kerosene as diluent, TBP as carrier, SPAN 80 as surfactant and (NH4)2CO3 solution as stripping phase. The extraction of chromium (VI) has been studied under various experimental conditions and have been determined the

Recep Ali Kumbasar

2010-01-01

312

Potential commercial applications of microbial surfactants.  

PubMed

Surfactants are surface-active compounds capable of reducing surface and interfacial tension at the interfaces between liquids, solids and gases, thereby allowing them to mix or disperse readily as emulsions in water or other liquids. The enormous market demand for surfactants is currently met by numerous synthetic, mainly petroleum-based, chemical surfactants. These compounds are usually toxic to the environment and non-biodegradable. They may bio-accumulate and their production, processes and by-products can be environmentally hazardous. Tightening environmental regulations and increasing awareness for the need to protect the ecosystem have effectively resulted in an increasing interest in biosurfactants as possible alternatives to chemical surfactants. Biosurfactants are amphiphilic compounds of microbial origin with considerable potential in commercial applications within various industries. They have advantages over their chemical counterparts in biodegradability and effectiveness at extreme temperature or pH and in having lower toxicity. Biosurfactants are beginning to acquire a status as potential performance-effective molecules in various fields. At present biosurfactants are mainly used in studies on enhanced oil recovery and hydrocarbon bioremediation. The solubilization and emulsification of toxic chemicals by biosurfactants have also been reported. Biosurfactants also have potential applications in agriculture, cosmetics, pharmaceuticals, detergents, personal care products, food processing, textile manufacturing, laundry supplies, metal treatment and processing, pulp and paper processing and paint industries. Their uses and potential commercial applications in these fields are reviewed. PMID:10855707

Banat, I M; Makkar, R S; Cameotra, S S

2000-05-01

313

Chemical demulsification of petroleum emulsions using oil-soluable demulsifiers  

Microsoft Academic Search

This paper investigates the factors affecting the coalescence and interfacial behavior of water- in-crude-oil emulsions in the presence of oil-soluble demulsifiers. The emulsion-breaking characteristics and interfacial properties of East Texas Crude and a model system were compared. The variation of interfacial tension with demulsifier concentration for the model system was ascertained by measuring the interfacial tensions between the oil and

Mark A. Krawczyk; Darsh T. Wasan; Chandrashekar Shetty

1991-01-01

314

Nanoassembly of surfactants with interfacial drug-interactive motifs as tailor-designed drug carriers.  

PubMed

PEGylated lipopeptide surfactants carrying drug-interactive motifs specific for a peptide-nitroxide antioxidant, JP4-039, were designed and constructed to facilitate the solubilization of this drug candidate as micelles and emulsion nanoparticles. A simple screening process based on the ability that prevents the formation of crystals of JP4-039 in aqueous solution was used to identify agents that have potential drug-interactive activities. Several protected lysine derivatives possessing this activity were identified, of which ?-Fmoc-?-t-Boc lysine is the most potent, followed by ?-Cbz- and ?-iso-butyloxycarbonyl-?-t-Boc-lysine. Using a polymer-supported liquid-phase synthesis approach, a series of synthetic lipopeptide surfactants with PEG headgroup, varied numbers and geometries of ?-Fmoc or ?-Cbz-lysyl groups located at interfacial region as the drug-interactive domains, and oleoyl chains as the hydrophobic tails were synthesized. All ?-Fmoc-lysyl-containing lipopeptide surfactants were able to solubilize JP4-039 as micelles, with enhanced solubilizing activity for surfactants with increased numbers of ?-Fmoc groups. The PEGylated lipopeptide surfactants with ?-Fmoc-lysyl groups alone tend to form filamentous or wormlike micelles. The presence of JP4-039 transformed ?-Fmoc-containing filamentous micelles into dots and barlike mixed micelles with substantially reduced sizes. Fluorescence quenching and NMR studies revealed that the drug and surfactant molecules were in close proximity in the complex. JP4-039-loaded emulsion carrying ?-Cbz-containing surfactants demonstrated enhanced stability over drug-loaded emulsion without lipopeptide surfactants. JP4-039 emulsion showed a significant mitigation effect on mice exposed to a lethal dose of radiation. PEGylated lipopeptides with an interfacially located drug-interactive domain are therefore tailor-designed formulation materials potentially useful for drug development. PMID:23244299

Gao, Xiang; Huang, Yixian; Makhov, Alexander M; Epperly, Michael; Lu, Jianqin; Grab, Sheila; Zhang, Peijun; Rohan, Lisa; Xie, Xiang-Qun; Wipf, Peter; Greenberger, Joel; Li, Song

2012-12-17

315

Micellization of true amphoteric surfactants.  

PubMed

The physical chemical behavior of a series of N-alkyl amino acid-based surfactants has been investigated. The series comprises four different types of amino acids as polar headgroups: glycine, aminomalonic acid, aspartic acid and glutamic acid, and for each type three homologues were synthesized: the octyl, decyl and dodecyl derivative. Aminomalonic acid, aspartic acid and glutamic acid are dicarboxylic amino acids with one, two and three methylene groups as spacer between the carboxylic groups, respectively. Compared with the more common N-acyl surfactants based on the same amino acids, many of the N-alkyl derivatives exhibited relatively high Krafft temperatures. The N-alkyl derivatives also had considerably lower critical micelle concentrations (CMCs) and they gave low values of surface tension at the CMC. The length of the spacer between the two carboxylic groups did not much influence the micellization. Some of the surfactants, in particular the lower homologues of N-alkylglycinate surfactants, gave unusually low surface tension values. The low values are most likely due to formation of a mixed monolayer at the surface, comprising of alternating anionic N-alkylglycinate and cationic N-protonated-N-alkylglycine. In a plot of conductivity vs. surfactant concentration there was no kink on the curve around the CMC, as determined by tensiometry. The absence of such a kink is in accordance with the view that self-assembly of the N-alkyl amino acid-based surfactants involves formation of mixed micelles consisting of alternating N-alkyl amino acid anion and N-protonated-N-alkyl amino acid also in the bulk solution. The protonation of the N-alkyl amino acid anion, which generates hydroxyl ions, is driven by the energetically favorable formation of mixed micelles consisting of anionic and cationic amphiphiles. PMID:24112839

Li, Yunxiang; Holmberg, Krister; Bordes, Romain

2013-09-10

316

Surfactants and Subsurface Remediation.  

National Technical Information Service (NTIS)

Because of the limitations of pump-and-treat technology, attention is now focused on the feasibility of surfactant use to increase its efficiency. Surfactants have been studied for use in soil washing and enhanced oil recovery. Although similarities exist...

C. C. West J. H. Harwell

1992-01-01

317

Optimization of metalworking fluid microemulsion surfactant concentrations for microfiltration recycling.  

PubMed

Microfiltration can be used as a recycling technology to increase metalworking fluid (MWF) life span, decrease procurement and disposal costs, and reduce occupational health risks and environmental impacts. The cost-effectiveness of the process can be increased by minimizing fouling interactions between MWFs and membranes. This paper reports on the development of a microfiltration model that establishes governing relationships between MWF surfactant system characteristics and microfiltration recycling performance. The model, which is based on surfactant adsorption/desorption kinetics, queueing theory, and coalescence kinetics of emulsion droplets, is verified experimentally. An analysis of the model and supporting experimental evidence indicates that the selection of surfactant systems minimally adsorb to membranes and lead to a high activation energy of coalescence results in a higher MWF flux through microfiltration membranes. The model also yields mathematical equations that express the optimal concentrations of anionic and nonionic surfactants with which microfiltration flux is maximized for a given combination of oil type, oil concentration, and surfactant types. Optimal MWF formulations are demonstrated for a petroleum oil MWF using a disulfonate/ ethoxylated alcohol surfactant package and for several vegetable oil MWFs using a disulfonate/ethoxylated glyceryl ester surfactant package. The optimization leads to flux increases ranging from 300 to 800% without impact on manufacturing performance. It is further shown that MWF reformulation efforts directed toward increasing microfiltration flux can have the beneficial effect of increasing MWF robustness to deterioration and flux decline in the presence of elevated concentrations of hardwater ions. PMID:17328218

Zhao, Fu; Clarens, Andres; Skerlos, Steven J

2007-02-01

318

Stability of cellulose lyotropic liquid crystal emulsions  

NASA Astrophysics Data System (ADS)

We studied a new kind of W/O emulsions based on a lyotropic liquid crystal as the aqueous droplet phase. The cholesteric phase, a solution hydroxypropyl cellulose in water was dispersed in the continuous oil matrix, paraffin oil or heptane. We made a specific choice of surfactant in order to impose director anchoring conditions at the oil-water interface and orient the liquid crystal inside the droplet. The strong anchoring conditions resulted in a topological defect inside the droplets of size above the critical value R^*. The defect elastic energy creates a barrier against droplet coalescence, the effect of topological size selection. We have studied the orientation of the director inside the droplets and their size distribution.

Tixier, T.; Heppenstall-Butler, M.; Terentjev, E. M.

2005-12-01

319

An investigation of the versatile antioxidant mechanisms of action of rosmarinate alkyl esters in oil-in-water emulsions.  

PubMed

The antioxidant polar paradox postulates that nonpolar antioxidants are more effective in oil-in-water emulsions than polar antioxidants. However, this trend is often not observed with antioxidants esterified with acyl chains to vary their polarity. In this study, the nonpolar eicosyl rosmarinate (20 carbons, R20) was less effective at inhibiting lipid oxidation in oil-in-water emulsions than esters with shorter fatty acyl chains such as butyl (R4), octyl (R8), and dodecyl (R12) esters. Interestingly, in the presence of surfactant micelles, the antioxidant activity of R20 was significantly increased while the antioxidant activity of R4 and R12 was slightly decreased. The presence of surfactant micelles increased the concentration of R20 at the interface of the surfactant micelles and/or emulsion droplets as determined by partitioning studies, front-face fluorescence properties, and the ability of R20 to interact with the interfacial probe, 4-hexadecylbenzenediazonium. A possible explanation for why the antioxidant activity of R20 was so dramatically increased by surfactant micelles is that a portion of the nonpolar R20 localizes in the emulsion droplet core and the surfactant micelles are able to increase the interfacial concentrations of R20 and thus its ability to scavenge free radicals produced from the decomposition of interfacial lipid hydroperoxides. PMID:22324394

Panya, Atikorn; Laguerre, Mickaël; Bayrasy, Christelle; Lecomte, Jérôme; Villeneuve, Pierre; McClements, D Julian; Decker, Eric A

2012-02-29

320

Partition behavior of surfactants, butanol, and salt during application of density-modified displacement of dense non-aqueous phase liquids.  

PubMed

Density-modified displacement (DMD) is a recent approach for removal of trapped dense NAPL (DNAPL). In this study, butanol and surfactant are contacted with the DNAPL to both reduce the density as well as release the trapped DNAPL (perchloroethylene: PCE). The objective of the study was to determine the distribution of each component (e.g., butanol, surfactant, water, PCE) between the original aqueous and PCE phases during the application of DMD. The results indicated that the presence of the surfactant increased the amount of n-butanol required to make the NAPL phase reach its desired density. In addition, water and anionic surfactant were found to partition along with the BuOH into the PCE phase. The water also found partitioned to reverse micelles in the modified phase. Addition of salt was seen to increase partitioning of surfactant to BuOH containing PCE phase. Subsequently, a large amount of water was solubilized into reverse micelles which lead to significantly increase in volume of the PCE phase. This work thus demonstrates the role of each component and the implications for the operation design of an aquifer treatment using the DMD technique. PMID:23385206

Damrongsiri, S; Tongcumpou, C; Sabatini, D A

2013-01-16

321

Colloidal particles in emulsions  

Microsoft Academic Search

We propose a statistical mechanical model for colloidal particles suspended in an emulsion of liquid droplets. The particles are modeled as hard spheres. The interaction between droplets is also hard, but the particles are able to penetrate the droplets. A swelling of droplets is taken into account to ensure material conservation of the droplet liquid. Hence the presence of the

Francisco L. Román; Matthias Schmidt; Hartmut Löwen

2000-01-01

322

Polymerized Asphalt Emulsion.  

National Technical Information Service (NTIS)

It has been claimed that polymerized asphalt emulsion has outstanding characteristics of elasticity, adhesion, and cohesion which allows its use in seal coats in high speed, high volume roads, such as interstate highways. Another use would be on a lower c...

S. Q. Kidd

1990-01-01

323

Cellular Structure of Emulsions  

Microsoft Academic Search

THE letters and photographs published on this subject do not make it quite clear whether the cellular structure observed is confined to the surface, or exists in the interior of the emulsion. Superficial cellular structure is by no means uncommon, and is shown to advantage by thin layers of heavy tar-oil or benzaldehyde on the surface of water. If the

Chas. R. Darling

1914-01-01

324

Silicone surfactants—new developments  

Microsoft Academic Search

Silicone surfactants—copolymers of silicone and polyethers—are useful for applications in which their high surface activity and silicone character provide performance advantages. They have recently been shown to enhance the efficiency of microemulsions. Systematic studies of their phase behavior continues to expand our knowledge of the self-assembly of large molecules. They are beginning to be used to prepare nanostructured materials. The

Randal M Hill

2002-01-01

325

Superhydrophobic and superoleophilic PVDF membranes for effective separation of water-in-oil emulsions with high flux.  

PubMed

A superhydrophobic-superoleophilic PVDF membrane is fabricated via an inert solvent-induced phase inversion for effective separation of both micrometer and nanometer-sized surfactant-free and surfactant-stabilized water-in-oil emulsions solely driven by gravity, with high separation efficiency (oil purity in filtrate after separation > 99.95 wt%) and high flux, which is several times higher than those of commercial filtration membranes and reported materials with similar permeation properties. PMID:23418068

Zhang, Wenbin; Shi, Zhun; Zhang, Feng; Liu, Xia; Jin, Jian; Jiang, Lei

2013-02-18

326

Formation and consolidation of filter cake in microfiltration of emulsion–slurry  

Microsoft Academic Search

The dynamic behaviors of unstirred dead-end microfiltration were explored under constant pressure conditions using a binary dispersion of oil-in-water (O\\/W) emulsion and polymethyl-methacrylate (PMMA) slurry, which is referred to as emulsion–slurry. The Ruth filtration coefficient determined from the flux decline data increased steadily during the course of filtration, and then a bilayer filter cake formed composed of the upper emulsion

E. Iritani; S. Matsumoto; N. Katagiri

2008-01-01

327

Water-in-Oil Micro emulsion Promoted Thin Layer Chromatographic Separations of Phenol Compounds  

Microsoft Academic Search

The use of water-in-oil (w\\/o) micro emulsion as mobile phase in thin layer chromatography (TLC) to examine the migration behavior of phenol compounds is described. Twenty-one phenols were chromatographed using (w\\/o) micro emulsion systems consisting of sodium dodecyl sulphate (SDS) and cetyltrimethyl ammonium bromide (CTAB) with silica gel, alumina, cellulose and kieselguhr TLC plates. A (w\\/o) micro emulsion system comprising

A. Mohammad; I. A. Khan

328

Preparation characteristics of water-in-oil-in-water multiple emulsions using microchannel emulsification  

Microsoft Academic Search

Microchannel (MC) emulsification is a novel technique for preparing monodispersed emulsions. This study demonstrates preparing water-in-oil-in-water (W\\/O\\/W) emulsions using MC emulsification. The W\\/O\\/W emulsions were prepared by a two-step emulsification process employing MC emulsification as the second step. We investigated the behavior of internal water droplets penetrating the MCs. Using decane, ethyl oleate, and medium-chain triglyceride (MCT) as oil phases,

Shinji Sugiura; Mitsutoshi Nakajima; Koji Yamamoto; Satoshi Iwamoto; Tatsuya Oda; Mitsuo Satake; Minoru Seki

2004-01-01

329

A new strategy for imaging biomolecular events through interactions between liquid crystals and oil-in-water emulsions.  

PubMed

In this study, we demonstrate a new strategy to image biomolecular events through interactions between liquid crystals (LCs) and oil-in-water emulsions. The optical response had a dark appearance when a nematic LC, 4-cyano-4'-pentylbiphenyl (5CB), is in contact with emulsion droplets of glyceryl trioleate (GT). In contrast, the optical response had a bright appearance when 5CB is in contact with GT emulsions decorated with surfactants such as sodium oleate. Since lipase can hydrolyze GT and produce oleic acid, the optical response also displays a bright appearance after 5CB has been in contact with a mixture of lipase and GT emulsions. These results indicate the feasibility of monitoring biomolecular events through interactions between LCs and oil-in-water emulsions. PMID:23024975

Hu, Qiong-Zheng; Jang, Chang-Hyun

2012-10-01

330

Phase diagrams of a cold rolling emulsion for aluminum{copyright}  

SciTech Connect

Emulsions are complex metalworking fluids. In metal rolling the generally accepted {open_quotes}plate{close_quotes} mechanism results in a separation of the mixture inside the roll bite into a water phase and a surfactant/oil phase. The water phase cools the tools and the oil phase lubricates the interface between the metal and the tools. Rolling emulsions can be considered as ternary systems that consist of water, oil and surfactant. The oil and its additives can be considered as a single component. This paper describes the application of phase diagrams to an aluminum cold rolling emulsion and provides insights into the separation of the water and the oil lubricant phases. It is shown that the amount of water solubilized in the separated oil phase depends on the nature and amount of additives and surfactants, and on the temperature. The emulsions studied were compared using a special rolling device developed in the authors` laboratory and their tribological properties were related to the phase diagrams. 18 refs., 13 figs., 1 tab.

Deneuville, P. [Pechiney Crv, Voreppe (France); Charbonnier, P. [IRSID-LECES, Maizieres (France); Ravey, J.C. [Univ. of Nancy, Vandoeuvre (France)

1995-08-01

331

DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS  

SciTech Connect

There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases IFT with a minimum at about 0.2 M. Addition of surfactant decreases IFT further. In the absence of surfactant the minerals are oil wet after aging with crude oil. Addition of surfactant solution decreases the contact angle to intermediate wettability. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Plans for the next quarter include conducting adsorption, phase behavior and wettability studies.

Kishore K. Mohanty

2003-07-01

332

SURFACTANT - POLYMER INTERACTION FOR IMPROVED OIL RECOVERY  

SciTech Connect

The goal of this research is to use the interaction between a surfactant and a polymer for efficient displacement of tertiary oil by improving slug integrity, adsorption and mobility control. Surfactant--polymer flooding has been shown to be highly effective in laboratory-scale linear floods. The focus of this proposal is to design an inexpensive surfactant-polymer mixture that can efficiently recover tertiary oil by avoiding surfactant slug degradation high adsorption and viscous/heterogeneity fingering. A mixture comprising a ''pseudo oil'' with appropriate surfactant and polymer has been selected to study micellar-polymer chemical flooding. The physical properties and phase behavior of this system have been determined. A surfactant-polymer slug has been designed to achieve high efficiency recovery by improving phase behavior and mobility control. Recovery experiments have been performed on linear cores and a quarter 5-spot. The same recovery experiments have been simulated using a commercially available simulator (UTCHEM). Good agreement between experimental data and simulation results has been achieved.

Unknown

1998-10-01

333

The biophysical function of pulmonary surfactant.  

PubMed

Pulmonary surfactant lowers surface tension in the lungs. Physiological studies indicate two key aspects of this function: that the surfactant film forms rapidly; and that when compressed by the shrinking alveolar area during exhalation, the film reduces surface tension to very low values. These observations suggest that surfactant vesicles adsorb quickly, and that during compression, the adsorbed film resists the tendency to collapse from the interface to form a 3D bulk phase. Available evidence suggests that adsorption occurs by way of a rate-limiting structure that bridges the gap between the vesicle and the interface, and that the adsorbed film avoids collapse by undergoing a process of solidification. Current models, although incomplete, suggest mechanisms that would partially explain both rapid adsorption and resistance to collapse as well as how different constituents of pulmonary surfactant might affect its behavior. PMID:18632313

Rugonyi, Sandra; Biswas, Samares C; Hall, Stephen B

2008-07-16

334

Pharmaceutical compositions comprising an amphoteric surfactant an alkoxylated cetyl alcohol and a polar drug  

US Patent & Trademark Office Database

A formulation, for example an oil-in-water emulsion, comprising an amphoteric surfactant, alkoxylated cetyl alcohol and a polar drug. The drug may be sodium cromoglycate or nedocromil sodium. The formulation may be useful in the treatment of skin disease such as atopic dermatitis.

2006-09-19

335

Double Emulsion Templated Celloidosomes  

NASA Astrophysics Data System (ADS)

We present a novel approach for fabricating celloidosomes, which represent a hollow and spherical three-dimensional self-assembly of living cells encapsulating an aqueous core. Glass- capillary microfluidics is used to generate monodisperse water-in-oil-in-water double emulsion templates using lipids as stabilizers. Such templates allow for obtaining single but also double concentric celloidosomes. In addition, after a solvent removal step the double emulsion templates turn into monodisperse lipid vesicles, whose membrane spontaneously phase separates when choosing the adequate lipid composition, providing the adequate scaffold for fabricating Janus-celloidosomes. These structures may find applications in the development of bioreactors in which the synergistic effects of two different types of cells selectively adsorbed on one of the vesicle hemispheres may be exploited.

Arriaga, Laura R.; Marquez, Samantha M.; Kim, Shin-Hyun; Chang, Connie; Wilking, Jim; Monroy, Francisco; Marquez, Manuel; Weitz, David A.

2012-02-01

336

Aqueous rubberized coal tar emulsion  

SciTech Connect

An aqueous rubberized coal tar emulsion composition especially suitable for coating and sealing bituminous substrates containing asphalt such as asphalt pavement and the like, the coal tar emulsion composition comprising a major portion of commercial coal tar emulsion and water admixed with a small amount of a carboxylated butadiene/styrene/acid copolymer latex having a particular particle size. The emulsion composition may additionally include a fine aggregate filler material such as sand. The coal tar emulsion composition according to the invention is of a thixotropic nature and has the ability to maintain the fine aggregate when added and mixed therein in a homogeneous-like suspension. The emulsion composition when spread on an asphalt surface exhibits a high degree of spreadability and provides a sealing coating that has a long life.

Ladish, D.J.

1985-10-01

337

Vitamin E-enriched nanoemulsions formed by emulsion phase inversion: factors influencing droplet size and stability.  

PubMed

There is considerable interest in using nanoemulsions as delivery systems for lipophilic bioactive ingredients, such as oil-soluble vitamins. Nanoemulsions can be fabricated using either high-energy or low-energy methods, but the latter offer advantages in terms of low cost, higher energy efficiency, and simplicity of implementation. In this study, the emulsion phase inversion (EPI) method was used to produce food-grade nanoemulsions enriched with vitamin E acetate. The EPI method simply involves titrating water into a mixture containing oil and surfactant, which initially leads to the formation of a water-in-oil emulsion that then inverts into an oil-in-water emulsion. Oil composition, surfactant type, and surfactant-to-oil ratio (SOR) were all found to influence the particle size distribution of the systems produced. Nanoemulsions with a mean particle diameter of 40 nm could be produced at a final system composition of 2 wt% MCT, 8 wt%vitamin E acetate, and 20 wt% Tween 80. The EPI method was shown to be unsuitable for producing nanoemulsions from label-friendly surfactants, such as Quillaja saponin, whey protein, casein, and sucrose monoesters. The EPI method was more effective at producing nanoemulsions at high SOR than microfluidization, but much less effective at low SOR. PMID:23660020

Mayer, Sinja; Weiss, Jochen; McClements, David Julian

2013-04-22

338

Changes of the diffraction efficiency due to emulsions thicknesses in holographic gratings  

NASA Astrophysics Data System (ADS)

We analyze the behavior of the diffraction efficiency as a function of the thickness of the relief holographic grating recorded on a phase emulsion composed by rosin and bromophenol blue (BPB) dye. The emulsions thicknesses are mainly due to the rosin quantity deposited on a substrate. We record holographic gratings on each emulsion using the spectral line ? = 457 nm of an argon laser, after this we developed the emulsion with a quick process. The diffraction efficiencies for each grating vary from 0.25% to 0.62%.

Ibarra, J. C.; Ortiz-Gutiérrez, M.; Olivares-Pérez, A.; Obregón-Pulido, G.; Pérez-Cortés, M.

2007-10-01

339

Multiple emulsions for food use  

Microsoft Academic Search

Numerous investigations were done to describe the effects of different food-grade components (e.g. lipid phases, emulsifiers, electrolytes, biopolymers, sugars) on the stability of multiple emulsions (type W\\/O\\/W and O\\/W\\/O). In addition to the emulsion composition, the stability of such systems also depends heavily on the emulsion matrix, influenced by the dispersing methods used. This review highlights recently published results of

Gerald Muschiolik

2007-01-01

340

Biocontrol efficacy of Colletotrichum truncatum for hemp sesbania (Sesbania exaltata) is enhanced with unrefined corn oil and surfactant  

Microsoft Academic Search

In greenhouse and field experiments, an oil-in-water emulsion of unrefined corn oil and Sil- wet L-77 increased the biological weed control efficacy of Colletotrichum truncatum (Schw.) Andrus et Moore for control of the weed, hemp sesbania (Sesbania exaltata (Raf.) Rydb. ex A.W. Hill). The surfactant - corn oil emulsion stimulated germination and appressoria for- mation in vivo and in vitro

C. DOUGLAS BOYETTE; ROBERT E. HOAGLAND; MARK A. WEAVER

2007-01-01

341

Combustion of Drops and Sprays of Heavy Fuel Oils and Their Emulsions.  

National Technical Information Service (NTIS)

An investigation was made to understand the combustion behavior of heavy fuels (No. 4 and No. 6 oils) and their emulsions. This study is an extension of an earlier study on a distillate fuel (No. 2) and its emulsion, and has been carried out in four parts...

S. R. Gollahalli M. L. Rasmussen S. M. Salek

1980-01-01

342

Experiments and network model of flow of oil-water emulsion in porous media  

NASA Astrophysics Data System (ADS)

Transport of emulsions in porous media is relevant to several subsurface applications. Many enhanced oil recovery (EOR) processes lead to emulsion formation and as a result conformance originating in the flow of a dispersed phase may arise. In some EOR processes, emulsion is injected directly as a mobility control agent. Modeling the flow of emulsion in porous media is extremely challenging due to the complex nature of the associated flows and numerous interfaces. The descriptions based on effective viscosity are not valid when the drop size is of the same order of magnitude as the pore-throat characteristic length scale. An accurate model of emulsion flow through porous media should describe this local change in mobility. The available filtration models do not take into account the variation of the straining and capturing rates with the local capillary number. In this work, we present experiments of emulsion flow through sandstone cores of different permeability and a first step on a capillary network model that uses experimentally determined pore-level constitutive relationships between flow rate and pressure drop in constricted capillaries to obtain representative macroscopic flow behavior emerging from microscopic emulsion flow at the pore level. A parametric analysis is conducted to study the effect of the permeability and dispersed phase droplet size on the flow response to emulsion flooding in porous media. The network model predictions qualitatively describe the oil-water emulsion flow behavior observed in the experiments.

Romero, Mao Illich; Carvalho, Marcio S.; Alvarado, Vladimir

2011-10-01

343

Experiments and network model of flow of oil-water emulsion in porous media.  

PubMed

Transport of emulsions in porous media is relevant to several subsurface applications. Many enhanced oil recovery (EOR) processes lead to emulsion formation and as a result conformance originating in the flow of a dispersed phase may arise. In some EOR processes, emulsion is injected directly as a mobility control agent. Modeling the flow of emulsion in porous media is extremely challenging due to the complex nature of the associated flows and numerous interfaces. The descriptions based on effective viscosity are not valid when the drop size is of the same order of magnitude as the pore-throat characteristic length scale. An accurate model of emulsion flow through porous media should describe this local change in mobility. The available filtration models do not take into account the variation of the straining and capturing rates with the local capillary number. In this work, we present experiments of emulsion flow through sandstone cores of different permeability and a first step on a capillary network model that uses experimentally determined pore-level constitutive relationships between flow rate and pressure drop in constricted capillaries to obtain representative macroscopic flow behavior emerging from microscopic emulsion flow at the pore level. A parametric analysis is conducted to study the effect of the permeability and dispersed phase droplet size on the flow response to emulsion flooding in porous media. The network model predictions qualitatively describe the oil-water emulsion flow behavior observed in the experiments. PMID:22181259

Romero, Mao Illich; Carvalho, Marcio S; Alvarado, Vladimir

2011-10-10

344

Sorption of Anionic Surfactants on Layered Double Hydroxides  

Microsoft Academic Search

In the present study we investigated the adsorption of sodium dodecyl- and octylsulfate, and sodium dodecyl- and octylbenzenesulfonate, on a layered double hydroxide (LDH) under controlled conditions. The results were compared to those obtained for the adsorption of surfactants on mineral oxides and on LDHs, showing that the behavior of surfactant adsorption on LDHs can be approximately explained by the

Paulo César Pavan; Eduardo Luis Crepaldi; João Barros Valim

2000-01-01

345

Surfactant injection process  

Microsoft Academic Search

Treatment of an oil reservoir with a slug of oil-soluble high equivalent weight sulfonated-hydrocarbon surfactant in a non-polar solvent followed by a water-soluble low equivalent weight sulfonated hydrocarbon surfactant in a polar solvent, greatly reduces the amount of divalent ion precipitation and surfactant absorption out of the reservoir rock, and also improves oil recovery. Alkyl aryl sulfonates can be fractionated

G. P. Ahearn; E. I. Sandvik

1970-01-01

346

[Surfactant to premature neonates].  

PubMed

Surfactant is a lipoprotein complex which reduces alveolar surface tension, thus reducing the work of respiration. Defective secretion of surfactant in the premature newborn infant gives rise to the respiratory distress syndrome (RDS). Several surfactant preparations, natural (purified) and synthetic, have been evolved. They have been used for prophylaxis and also therapy. Several controlled studies have shown decreased mortality, while the effect on neonatal complications and late results are still uncertain. PMID:1866827

Jacobsen, T; Verder, H

1991-07-29

347

Generation of antibubbles from core-shell double emulsion templates produced by microfluidics.  

PubMed

We report the preparation of antibubbles by microfluidic methods. More specifically, we demonstrate a two-step approach, wherein a monodisperse water-in-oil-in-water (W/O/W) emulsion of core-shell construction is first generated via microfluidics and freeze-dried thereafter to yield, upon subsequent reconstitution, an aqueous dispersion of antibubbles. Stable antibubbles are attained by stabilization of the air-water interfaces through a combination of adsorbed particles and polymeric surfactant. The antibubbles strongly resemble the double emulsion templates from which they were formed. When triggered to release, antibubbles show complete release of their cores within about 100 ms. PMID:23758211

Silpe, Justin E; Nunes, Janine K; Poortinga, Albert T; Stone, Howard A

2013-07-01

348

Competitive adsorption of sodium naphthenates and naturally occurring species at water-in-crude oil emulsion droplet surfaces  

Microsoft Academic Search

The stability of water-in-crude oil emulsions is partly due to a complex, rigid layer formed at the water droplet surface that is likely made of large molecules such as asphaltenes. In highly diluted bitumen, where water droplet surfaces are relatively free of low molecular weight surfactant species, surface rigidity is prevalent. The properties of this layer change dramatically upon addition

K. Moran; J. Czarnecki

2007-01-01

349

Role of emulsifier in the extraction of gold (III) ions from aqueous solutions using the emulsion liquid membrane technique  

Microsoft Academic Search

Extraction of gold (III) ions from aqueous solutions by two types of emulsifier using the emulsion liquid membrane technique was investigated. Experimental results for the batch extraction of gold (III) ions using a surfactant liquid membrane technique are presented. A comparison was made between a synthetic commercial and a novel, naturally based, biodegradable emulsifier. The effects of various parameters such

Ali Kargari; Tahereh Kaghazchi; Mansoureh Soleimani

2004-01-01

350

Transport of cadmium ions from zinc plant leach solutions through emulsion liquid membrane-containing Aliquat 336 as carrier  

Microsoft Academic Search

The zinc plant purification cake (CINKUR Co., Turkiye) was leached with sulphuric acid. The transport of cadmium from this leach solution-containing zinc, iron, copper, aluminum, cadmium, nickel and cobalt through emulsion liquid membrane (ELM) using amine extractant dissolved in kerosene as a mobile carrier was studied. The ELM consists of Aliquat 336 as a carrier, Span 80 as a surfactant,

Recep Ali Kumbasar

2008-01-01

351

LNAPL Removal from Unsaturated Porous Media using Surfactant Infiltration  

SciTech Connect

A series of unsaturated column experiments was performed to evaluate light non-aqueous phase liquid (LNAPL) fate and removal during surfactant solution infiltration. Surfactant-LNAPL phase behavior tests were conducted to optimize the remedial solutions. Packed sand and site sediment columns were first processed to establish representative LNAPL smear zone under unsaturated conditions. Infiltration of low-concentration surfactant was then applied in a stepwise flush mode, with 0.3 column pore volume (PV) of solution in each flush. The influence of infiltrated surfactant solution volume and pH on LNAPL removal was assessed. A LNAPL bank was observed at the very front of the first surfactant infiltration in each column, indicating that a very low surfactant concentration is needed to reduce the LNAPL-water interfacial tension sufficiently enough to mobilize trapped LNAPL under unsaturated conditions. More LNAPL was recovered as additional steps of surfactant infiltration were applied. Up to 99% LNAPL was removed after six infiltration steps, with less than 2.0 PV of total surfactant solution application, suggesting surfactant infiltration may be an effective method for vadose zone LNAPL remediation. The influence of pH tested in this study (3.99~10.85) was insignificant because the buffering capacity of the sediment kept the pH in the column higher than the zero point charge, pHzpc, of the sediment and therefore the difference between surfactant sorption was negligible.

Zhong, Lirong; Oostrom, Martinus

2012-11-19

352

Sacrificial adsorbate for surfactants utilized in chemical floods of enhanced oil recovery operations  

DOEpatents

The present invention is directed to a sacrificial or competitive adsorbate for surfactants contained in chemical flooding emulsions for enhanced oil recovery operations. The adsorbate to be utilized in the method of the present invention is a caustic effluent from the bleach stage or the weak black liquor from the digesters and pulp washers of the kraft pulping process. This effluent or weak black liquor is injected into an oil-bearing subterranean earth formation prior to or concurrent with the chemical flood emulsion and is adsorbed on the active mineral surfaces of the formation matrix so as to effectively reduce adsorption of surfactant in the chemical flood. Alternatively, the effluent or liquor can be injected into the subterranean earth formation subsequent to a chemical flood to displace the surfactant from the mineral surfaces for the recovery thereof.

Johnson, J.S. Jr.; Westmoreland, C.G.

1980-08-20

353

Mesoscopic simulation of the crossing dynamics at an entanglement point of surfactant threadlike micelles  

Microsoft Academic Search

The crossing dynamics at an entanglement point of surfactant threadlike micelles in an aqueous solution was studied using a mesoscopic simulation method, dissipative particle dynamics, with a coarse-grained surfactant model. The possibility of a phantom crossing, which is the relaxation mechanism for the pronounced viscoelastic behavior of surfactant threadlike micellar solution, was investigated. When two threadlike micelles were encountered at

Satoru Yamamoto; Shi-Aki Hyodo

2005-01-01

354

Reverse water-in-fluorocarbon emulsions for use in pressurized metered-dose inhalers containing hydrofluoroalkane propellants.  

PubMed

Pulmonary administration of drugs has demonstrated numerous advantages in the treatment of pulmonary diseases due to direct targeting to the respiratory tract. It enables avoiding the first pass effect, reduces the amount of drugs administered, targets drugs to specific sites and reduces their side effects. Reverse water-in-fluorocarbon (FC) emulsions are potential drug delivery systems for pulmonary administration using pressurized metered-dose inhalers (pMDI). The external phase of these emulsions consists of perfluorooctyl bromide (PFOB, perflubron), whereas their internal phase contains the drugs solubilized or dispersed in water. These emulsions are stabilized by a perfluoroalkylated dimorpholinophosphate (F8H11DMP), i.e. a fluorinated surfactant. This study demonstrates the possibility of delivering a reverse fluorocarbon emulsion via the pulmonary route using a CFC-free pMDI. Two hydrofluoroalkanes (HFAs) (Solkane(R) 134a and Solkane(R) 227) were used as propellants, and various solution (or emulsion)/propellant ratios (1/3, 1/2, 2/3, 1/1, 3/2, 3/1 v/v) were investigated. The insolubility of water (with or without the fluorinated surfactant F8H11DMP) in both HFA 227 and HFA 134a was demonstrated. PFOB and the reverse emulsion were totally soluble or dispersible in all proportions in both propellants. This study demonstrated also that the reverse FC emulsion can be successfully used to deliver caffeine in a homogeneous and reproducible way. The mean diameter of the emulsion water droplets in the pressured canister was investigated immediately after packaging and after 1 week of storage at room temperature. Best results were obtained with emulsion/propellant ratios comprised between 2/3 and 3/2, and with HFA 227 as propellant. PMID:11996829

Butz, N; Porté, C; Courrier, H; Krafft, M P; Vandamme, Th F

2002-05-15

355

DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS  

SciTech Connect

There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Anionic surfactants (SS-6656, Alfoterra 35, 38, 63,65,68) have been identified which can change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant DTAB with a West Texas crude oil in the presence of Na{sub 2}CO{sub 3}. All the carbonate surfaces (Lithographic Limestone, Marble, Dolomite and Calcite) show similar behavior with respect to wettability alteration with surfactant 4-22. Anionic surfactants (5-166, Alfoterra-33 and Alfoterra-38 and Alfoterra-68), which lower the interfacial tension with a West Texas crude oil to very low values (<10{sup -2} nM/m), have also been identified. Plans for the next quarter include conducting wettability, mobilization, and imbibition studies.

Kishore K. Mohanty

2004-01-01

356

Turbulent drag reduction in nonionic surfactant solutions  

NASA Astrophysics Data System (ADS)

There are only a few studies on the drag-reducing effect of nonionic surfactant solutions which are nontoxic and biodegradable, while many investigations of cationic surfactant solutions have been performed so far. First, the drag-reducing effects of a nonionic surfactant (AROMOX), which mainly consisted of oleyldimethylamineoxide, was investigated by measuring the pressure drop in the pipe flow at solvent Reynolds numbers Re between 1000 and 60 000. Second, we investigated the drag-reducing effect of a nonionic surfactant on the turbulent boundary layer at momentum-thickness Reynolds numbers Re? from 443 to 814 using two-component laser-Doppler velocimetry and particle image velocimetry systems. At the temperature of nonionic surfactant solutions, T=25 °C, the maximum drag reduction ratio for AROMOX 500 ppm was about 50%, in the boundary layer flow, although the drag reduction ratio was larger than 60% in pipe flow. Turbulence statistics and structures for AROMOX 500 ppm showed the behavior of typical drag-reducing flow such as suppression of turbulence and modification of near-wall vortices, but they were different from those of drag-reducing cationic surfactant solutions, in which bilayered structures of the fluctuating velocity vectors were observed in high activity.

Tamano, Shinji; Itoh, Motoyuki; Kato, Katsuo; Yokota, Kazuhiko

2010-05-01

357

Molecular simulation of surfactant-assisted protein refolding  

NASA Astrophysics Data System (ADS)

Protein refolding to its native state in vitro is a challenging problem in biotechnology, i.e., in the biomedical, pharmaceutical, and food industry. Protein aggregation and misfolding usually inhibit the recovery of proteins with their native states. These problems can be partially solved by adding a surfactant into a suitable solution environment. However, the process of this surfactant-assisted protein refolding is not well understood. In this paper, we wish to report on the first-ever simulations of surfactant-assisted protein refolding. For these studies, we defined a simple model for the protein and the surfactant and investigated how a surfactant affected the folding behavior of a two-dimensional lattice protein molecule. The model protein and model surfactant were chosen such that we could capture the important features of the folding process and the interaction between the protein and the surfactant, namely, the hydrophobic interaction. It was shown that, in the absence of surfactants, a protein in an ``energy trap'' conformation, i.e., a local energy minima, could not fold into the native form, which was characterized by a global energy minimum. The addition of surfactants created folding pathways via the formation of protein-surfactant complexes and thus enabled the conformations that fell into energy trap states to escape from these traps and to form the native proteins. The simulation results also showed that it was necessary to match the hydrophobicity of surfactant to the concentration of denaturant, which was added to control the folding or unfolding of a protein. The surfactants with different hydrophobicity had their own concentration range on assisting protein refolding. All of these simulations agreed well with experimental results reported elsewhere, indicating both the validity of the simulations presented here and the potential application of the simulations for the design of a surfactant on assisting protein refolding.

Lu, Diannan; Liu, Zheng; Liu, Zhixia; Zhang, Minlian; Ouyang, Pingkai

2005-04-01

358

Selective separation of nickel from cobalt in ammoniacal solutions by emulsion type liquid membranes using 8-hydroxyquinoline (8HQ) as mobile carrier  

Microsoft Academic Search

The selective separation and concentration of nickel from ammoniacal solutions containing nickel and cobalt by an emulsion liquid membrane (ELM) technique using 8-hydroxyquinoline (8-HQ) as carrier has been examined. The emulsion liquid membrane consists of a diluent (kerosene), a surfactant (ECA 4360J), a carrier (8-HQ), and a stripping solution (0.025 M EDTA solution, buffered at pH 4.0). Cobalt (II) in the

R. A. Kumbasar; S. Kasap

2009-01-01

359

Recovery and pre-concentration of americium (III) from dilute acid solutions using an emulsion liquid membrane containing di-2-ethylhexyl phosphoric acid (D2EHPA) as extractant  

Microsoft Academic Search

An emulsion liquid membrane (ELM) containing di-2-ethylhexylphosphoric acid (D2EHPA) as the carrier extractant and SPAN 80\\u000a as the surfactant was used to pre-concentrate Am3+ from dilute acid solutions. Effects of various factors such as: external phase pH, internal phase conditions, equilibration\\u000a time, D2EHPA concentration, SPAN 80 concentration, etc. on Am3+ mass transfer were investigated. Emulsion was broken by the addition

S. Chowta; P. K. Mohapatra; S. C. Tripathi; B. S. Tomar; V. K. Manchanda

2010-01-01

360

SURFACTANTS AND SUBSURFACE REMEDIATION  

EPA Science Inventory

Because of the limitations of pump-and-trat technology, attention is now focused on the feasibility of surfactant use to increase its efficiency. Surfactants have been studied for use in soil washing and enhanced oil recovery. Although similarities exist between the application...

361

Surfactant flooding system  

SciTech Connect

A method is described for modifying a sulfonate surfactant flooding system and recovering hydrocarbons from an underground formation. The system comprises one or more sulfonate surfactant slugs and a following polymer drive fluid to be injected into an underground hydrocarbon formation to permit the use of increased salinity in the polymer drive fluid without a substantial decrease in recovery efficiency. The method comprises: adding about 0.05% to about 1.0% by weight of a divalent metal cation to the one or more surfactant slugs of the surfactant flooding system to give a total concentration of about 0.1% to about 1.0% by weight of divalent metal cations and injecting the one or more surfactant slugs into the formation; and adding about 0.1% to about 1.5% by weight of a solubilizer compound to the polymer drive fluid and injecting the polymer drive fluid into the formation and recovering hydrocarbons from the formation.

Maddox, J. Jr.

1987-05-26

362

Emulsions of crude glycerin from biodiesel processing with fuel oil for industrial heating.  

PubMed

There is considerable interest in using crude glycerin from biodiesel production as a heating fuel. In this work crude glycerin was emulsified into fuel oil to address difficulties with ignition and sustained combustion. Emulsions were prepared with several grades of glycerin and two grades of fuel oil using direct and phase inversion emulsification. Our findings reveal unique surfactant requirements for emulsifying glycerin into oil; these depend on the levels of several contaminants, including water, ash, and components in MONG (matter organic non-glycerin). A higher hydrophile-lipophile balance was required for a stable emulsion of crude glycerin in fuel oil compared to water in fuel oil. The high concentration of salts from biodiesel catalysts generally hindered emulsion stability. Geometric close-packing of micelles was carefully balanced to mechanically stabilize emulsions while also enabling low viscosity for pumping and fuel injection. Phase inversion emulsification produced more stable emulsions than direct emulsification. Emulsions were tested successfully as fuel for a waste oil burner. PMID:23331034

Mize, Hannah E; Lucio, Anthony J; Fhaner, Cassie J; Pratama, Fredy S; Robbins, Lanny A; Karpovich, David S

2013-02-01

363

Micro magnetofluidics: droplet manipulation of double emulsions based on paramagnetic ionic liquids.  

PubMed

The ability to control and manipulate discrete fluid droplets by magnetic fields offers new opportunities in microfluidics. A surfactant-free and easy to realize technique for the continuous generation of double emulsion droplets, composed of an organic solvent and a paramagnetic ionic liquid, is applied. The inner phase of the emulsion droplet consists of imidazolium-based ionic liquids with either iron, manganese, nickel or dysprosium containing anions which provide paramagnetic behaviour. The double emulsion droplets are dispersed in a continuous phase of FC-40. All substances - the organic phase, the paramagnetic ionic liquid and the continuous phase -are immiscible. The magnetic properties of ionic liquids allow, through the influence of external magnetic fields, the manipulation of individual emulsion droplets such as capture and release, rotation and distortion. Arrays of magnets allow a coalescence of emulsion droplets and their subsequent mixing by flowing through an alternating permanent magnetic field. In addition, the double emulsion droplets can be split and reunified, or continuously separated into their original phases. PMID:24108233

Misuk, Viktor; Mai, Andreas; Giannopoulos, Konstantinos; Alobaid, Falah; Epple, Bernd; Loewe, Holger

2013-10-29

364

Preparation of solid lipid nanoparticles from W/O/W emulsions: preliminary studies on insulin encapsulation.  

PubMed

A method to produce solid lipid nanoparticles (SLN) from W/O/W multiple emulsions was developed applying the solvent-in-water emulsion-diffusion technique. Insulin was chosen as hydrophilic peptide drug to be dissolved in the acidic inner aqueous phase of multiple emulsions and to be consequently carried in SLN. Several partially water-miscible solvents with low toxicity were screened in order to optimize emulsions and SLN composition, after assessing that insulin did not undergo any chemical modification in the presence of the different solvents and under the production process conditions. SLN of spherical shape and with mean diameters in the 600-1200 nm range were obtained by simple water dilution of the W/O/W emulsion. Best results, in terms of SLN mean diameter and encapsulation efficiencies, were obtained using glyceryl monostearate as lipid matrix, butyl lactate as a solvent, and soy lecithin and Pluronic F68 as surfactants. Encapsulation efficiencies up to 40% of the loaded amount were obtained, owing to the actual multiplicity of the system; the use of multiple emulsion-derived SLN can be considered a useful strategy to encapsulate a hydrophilic drug in a lipid matrix. PMID:18785076

Gallarate, Marina; Trotta, Michele; Battaglia, Luigi; Chirio, Daniela

2009-08-01

365

The factors affecting on Bitumen Emulsion properties  

Microsoft Academic Search

Need to proper roads and highways will increase with increasing automotive industry and development of cities and countries. Among petroleum products used in road construction and asphalt application for soil stability and adhesion between layers of asphalt are bitumen soluble and Bitumen Emulsions. Bitumen Emulsions are subset of water emulsion that in this type of emulsion dispersed phase is lipophilic

H. Kazemi Esfeh; B. Ghanavati; R. Shojaei Arani

2010-01-01

366

Formulation of shear rate sensitive multiple emulsions  

Microsoft Academic Search

This work mainly concentrates on the formulation of W\\/O\\/W multiple emulsions capable of breaking and releasing their inner aqueous phase under shear rates compatible with agroalimentary, pharmaceutical and cosmetic applications. Three kinds of multiple emulsions were studied: one with a high concentration of primary emulsion, not viscosified in the external aqueous phase; multiple emulsions gelified with a synthetic polymer (Carbopol

V Muguet; M Seiller; G Barratt; O Ozer; J. P Marty; J. L Grossiord

2001-01-01

367

The onset of microscale tipstreaming with soluble nonionic surfactants  

NASA Astrophysics Data System (ADS)

Surfactants play a significant role in the formation of emulsion droplets in microfluidic devices. At specific concentrations and flow rates, tipstreaming is observed and micron-scale droplets are formed. To date, the role of the surfactant itself is not well understood. The timescales for surfactant mass transport including diffusion, adsorption, and desorption can all be significant in determining the local, instantaneous surface concentration. In this talk, we present microfluidic tipstreaming experiments using nonionic CiEj surfactants in which the hydrophobic tail length varies. We show that tipstreaming occurs only when adsorption is rapid enough for surfactant to adsorb but viscous stresses are strong enough to maintain a surface tension gradient. The experiments indicate that the allowable surface coverage for tipstreaming is very small, even though the bulk concentration is greater than the critical micelle concentration. We use a one-dimensional kinetic-limited transport model to demonstrate that small surface coverages can lead to highly nonlinear effects like tipstreaming at these length and time scales.

Anna, Shelley; Alvarez, Nicolas; Lee, Wingki; Walker, Lynn

2010-11-01

368

Extraction of chromium (VI) from multicomponent acidic solutions by emulsion liquid membranes using TOPO as extractant  

Microsoft Academic Search

Experimental results for the extraction of chromium (VI) from multicomponent acidic solutions by emulsion liquid membrane (ELM) using trioctylphosphine oxide (TOPO) as extractant are presented. The membrane phase consists of kerosene as diluent, TOPO as extractant, ECA 4360J (a nonionic polyamine) as surfactant and (NH4)2CO3 solution as stripping phase. Effects of various parameters such as mixing speed, type and concentration

Recep Ali Kumbasar

2009-01-01

369

Selective Separation of Gallium from Acidic Leach Solutions by Emulsion Liquid Membranes  

Microsoft Academic Search

The separation and concentration of gallium from acidic leach solutions, containing various other ions such as iron, cobalt, nickel, zinc, cadmium, lead, copper, and aluminium, by an emulsion liquid membrane (ELM) technique using tributyl phosphate (TBP) as carrier has been presented. Liquid membrane consists of a diluent, a surfactant (ECA 4360J), and an extractant (TBP), and 0.1 M HCl or 0.1 M

R. A. Kumbasar; O. Tutkun

2006-01-01

370

Destabilisation of oil–water emulsions and separation by dissolved air flotation  

Microsoft Academic Search

The roles of aluminium and ferric sulphates as destabilising agents for oil–water emulsions that have been stabilised by a non-ionic surfactant (Span 20) are investigated in terms of oil removal. The effects of coagulant dose, pH, and the duration and intensity of both slow and fast mixing are considered. Electrokinetic measurements indicate that oil droplets have a negative zeta potential

A. A. Al-Shamrani; A. James; H. Xiao

2002-01-01

371

Stable silicone oil emulsion composition, article of manufacture, and method of fabric wrinkle control  

US Patent & Trademark Office Database

Silicone emulsion comprising: at least about 0.025% and less than about 10% of silicone oil; an active amount to emulsify said silicone oil and reduce surface tension of said composition of a surfactant system; and a an effective amount of a buffering system to maintain a pH of said composition to be at least about 6 for a period of at least about 3 months, are useful for controlling wrinkles in fabrics.

Frankenbach; Gayle Marie (Cincinnati, OH); Smith; John William (Milford, OH); Trinh; Toan (Maineville, OH); Bray, Jr.; Earl (Cincinnati, OH); Winder; Lisa Catherine (Cincinnati, OH); Chang; Su Yon (Cincinnati, OH); Raleigh; Mary Ellen (Mason, OH); Corona, III; Alessandro (Maineville, OH); Burns; Anthony James (West Chester, OH); Dinniwell; Alan Robert (Mason, OH)

2005-06-21

372

Emulsion-derived lithium manganese oxide powder for positive electrodes in lithium-ion batteries  

Microsoft Academic Search

Lithium manganese oxide (LiMn2O4) used as a positive-electrode material in lithium-ion batteries is prepared by a new water-in-oil emulsion process. An aqueous solution containing lithium and manganese cations is emulsified in kerosene by adding sorbitan monooleate as the surfactant. When the precursor solution is agitated by a magnetic mixer, impure products are obtained. LiMn2O4 is formed along with residual Mn2O3

Chung-Hsin Lu; Shang-Wei Lin

2001-01-01

373

Some features of breakdown in water-in-oil-in-water multiple emulsions  

Microsoft Academic Search

The purpose of this work was to define and record the critical features of breakdown in different water-in-oil-in-water (W\\/O\\/W) emulsions stabilized by nonionic surfactants. Various filming techniques (time-lapse, continuous, and high-speed cinemicrography) were used in conjunction with conventional photomicrography. Some effort also has been directed toward analysis of the stability of W\\/O\\/W systems by considering the oil-water surface area changes

A. T. Florence; D. Whitehill

1981-01-01

374

Interest for delivery of cocaethylene in a sustained release emulsion vs saline evaluated on behavioral sensitization in naive and cocaine-sensitized mice  

Microsoft Academic Search

Rationale  Repeated administration of psychostimulant elicits behavioral sensitization, characterized by an augmented locomotor response\\u000a to a subsequent challenge injection. This sensitization is paralleled by neural adaptations. Evidences suggest that the rate\\u000a at which drugs of abuse are delivered to the brain play a key role in this plasticity. Cocaethylene is a pharmacologically\\u000a active homolog of cocaine, known to have a pharmacokinetic

Florence Noble; Mario Sanchez; William Lowenstein

2007-01-01

375

Surfactant flooding oil recovery process  

Microsoft Academic Search

The effectiveness of an aqueous, saline surfactant fluid, especially one containing as essentially the only surfactant an alkylpolyalkoxyalkyl sulfonate or an alkylarylpolyalkoxyalkyl sulfonate for oil recovery by surfactant flooding is increased substantially if the fluid is subjected to a high shear rate for a predetermined period of time prior to injecting the fluid into the oil containing formation. The surfactant

Schievelbein

1980-01-01

376

Double emulsions — scope, limitations and new achievements  

Microsoft Academic Search

Multiple emulsions are complex systems, termed “emulsions of emulsions”, i.e. the droplets of the dispersed phase contain even smaller dispersed droplets themselves. Each dispersed globule in the double emulsion is separated from the aqueous phase by a layer of oil-phase compartments.Double emulsions have significant potential in many applications since, at least in theory, they can serve as an entrapping reservoir

Nissim Garti

1997-01-01

377

Synthesis and characterization of ?-CD-coated polystyrene microspheres by ?-ray radiation emulsion polymerization.  

PubMed

Polystyrene (PS) microspheres coated with ?-cyclodextrin (?-CD) were fabricated via ?-ray-induced emulsion polymerization in a ternary system of styrene/?-CD/water (St/?-CD/water). The solid inclusion complex of St and ?-CD particles formed at the St droplets-water interface can stabilize the emulsion as the surfactant. TEM and XPS results showed that ?-CD remains on the surface of PS particles. The average size of the PS particles increases from 186 to 294 nm as the weight ratio of ?-CD to St rises from 5% to 12.5%. The water contact angle (CA) of PS latex film is lower than 90°, and reduces with the ?-CD content even to 36°. Thus, this work provides a new and one-pot strategy to surface hydrophilic modification on hydrophobic polymer particles with cyclodextrins through radiation emulsion polymerization. PMID:22887797

Xu, Dezhi; Wang, Mozhen; Ge, Xuewu; Lam, Michael Hon-Wah

2012-08-10

378

Asphalt Emulsion Technology: Review of Asphalt Emulsion Residue Procedures. Transportation Research Circular E-C122.  

National Technical Information Service (NTIS)

Bituminous emulsion paving materials continue to be a challenging area of research and practical applications. Transportation Research Circular E-C102: Asphalt Emulsion Technology presented an overview of asphalt emulsion technology covering its chemistry...

2007-01-01

379

Surfactant compositions for steamfloods  

SciTech Connect

This patent describes a composition useful for displacing oil within the pores of or for producing oil from an oil-containing reservoir, comprising: (a) an aqueous liquid, present in the composition, at a temperature substantially equalling its boiling temperature at the reservoir pressure, in both a liquid phase and vapor phase of steam, and (b) a functionally effective amount of a surfactant mixture consisting essentially of an /alpha/-olefin sulfonate surfactant and mono-or di-alklylated diphenyl oxide sulfonate surfactant wherein the alkyl portion of the alkylated diphenyl oxide sulfonate contains from about 6 to about 24 carbon atoms.

Lim, T.

1989-04-11

380

Linear viscoelasticity of emulsions : I. The effect of an interfacial film on the dynamic viscosity of nondilute emulsions  

Microsoft Academic Search

The dynamic viscosity of nondilute monodisperse emulsions is calculated by using a cell model. Two possibilities for describing the mechanical properties of the interfacial film between the internal and the external phase are considered: (A) the film is assigned a two-dimensional linear viscoelastic behavior and (B) the film is treated as a shell with finite thickness containing a Newtonian liquid.

M. Oosterbroek; J. Mellema

1981-01-01

381

Double Emulsions through Wettability Control in PDMS Microfluidic Devices  

NASA Astrophysics Data System (ADS)

Hydrodynamic Flow Focusing allows for the well-controlled production of monodisperse double and multiple emulsions. While this method of emulsification is well described for glass capillary devices, it has not yet been developed for PDMS devices that are readily accessible using soft-lithography. The reason is the difficulty of spatially controlling the wetting behavior of PDMS microchannels. We will present a novel technique of photopatterning that allows for the production of double emulsions in PDMS devices. Moreover, owing to an optimized setup, smaller droplets may be made down to a size range that was not accessible using the conventional approaches.

Holtze, Christian; Mele, Elisa; Weitz, David

2007-03-01

382

Self-assembly formation of palm-based esters nano-emulsion: A molecular dynamics study  

NASA Astrophysics Data System (ADS)

Palm-oil esters (POEs) are unsaturated and non-ionic esters that can be prepared by enzymatic synthesis from palm oil. Their nano-emulsion properties possess great potential to act as drug carrier for transdermal drug delivery system. A ratio of 75:5:20 (water/POEs/Span20) was chosen from homogenous region in the phase diagram of our previous experimental work to undergo molecular dynamics simulation. A 15 ns molecular dynamics simulation of nano-emulsion system (water/POEs/Span20) was carried out using OPLS-AA force field. The aggregations of the oil and surfactant molecules are observed throughout the simulation. After 8 ns of simulation, the molecules start to aggregate to form one spherical micelle where the POEs molecules are surrounded by the non-ionic surfactant (Span20) molecules with an average size of 4.2 ± 0.05 nm. The size of the micelle and the ability of palm-based nano-emulsion to self-assemble suggest that this nano-emulsion can potentially use in transdermal drug delivery system.

Abdul Rahman, Mohd. Basyaruddin; Huan, Qiu-Yi; Tejo, Bimo A.; Basri, Mahiran; Salleh, Abu Bakar; Rahman, Raja Noor Zaliha Abdul

2009-10-01

383

Surfactant-enhanced alkaline flooding for light oil recovery. Quarterly report, October 1--December 30, 1994  

SciTech Connect

The overall objective of this project is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12.0) for ultimate spontaneous emulsification and ultra-low tension. In addition, the novel concept of pH gradient design to optimize flood water conditions will be tested. The problem of characterizing emulsions in porous media is very important in enhanced oil recovery applications. This is usually accomplished by externally added or insitu generated surfactants that sweep the oil out of the reservoir. Emulsification of the trapped oil is one of the mechanisms of recovery. The ability to detect emulsions in the porous medium is therefore crucial to designing profitable flood systems. The capability of microwave dielectric techniques to detect emulsions in porous medium is demonstrated by mathematical modelling and by experiments. This quarter the dielectric properties of porous media are shown to be predicted adequately by treating it an an O/W type dispersion of sand grains in water. Dielectric measurements of emulsion flow in porous media show that dielectric techniques may be applied to determine emulsion characteristics in porous media. The experimental observations were confirmed by theoretical analysis.

Wasan, D.T.

1994-12-31

384

Modeling selected emulsions and double emulsions as memristive systems.  

PubMed

The recent development in basic and applied science and engineering of finely dispersed systems is presented in general, but more attention has been paid to the liquid-liquid finely dispersed systems or to the particular emulsions and double emulsions. The selected systems for theoretical and experimental research were emulsions and double emulsions that appeared in the pilot plant for extraction of uranium from wet phosphoric acid. The objective of this research was to try to provide a new or different approach to elaborate the complex phenomena that occur at developed liquid-liquid interfaces. New concepts were introduced, the first is a concept of an entity, and the corresponding classification of finely dispersed systems and the second concept consider the introduction of an almost forgotten basic electrodynamics element memristor, and the corresponding memristive systems. Based on these concepts a theory of electroviscoelasticity was proposed and experimentally corroborated using the selected representative liquid-liquid system. Also, it is shown that the droplet, and/or droplet-film structure, that is, selected emulsion and/or double emulsion may be considered as the particular example of memristive systems. PMID:22482789

Spasic, Aleksandar M; Jovanovic, Jovan M; Jovanovic, Mica

2012-03-21

385

Paraquat detoxication with multiple emulsions.  

PubMed

In this study, we show that detoxifying W/O/W multiple emulsions, prepared with an appropriate extractant/trapping couple, represent a promising technology for quick and safe poisoning treatments, with application to the highly toxic herbicide Paraquat, responsible of poisonings from low-dose exposure leading to several deaths every year. In vitro tests led to the choice of an appropriate extractant/trapping couple system with significant detoxication performance. In vivo tests showed (i) that rats receiving high doses of Paraquat, then a detoxifying emulsion, presented an increase from 50% to 100% of the MST (median survival time) and (ii) that no mortality was observed during 30 days with rats dosed with emulsions initially loaded with Paraquat at a concentration much higher than the lethal dose, proving the stability and the inocuity of the detoxifying multiple emulsion in the gastrointestinal tract. PMID:19635538

Frasca, S; Couvreur, P; Seiller, M; Pareau, D; Lacour, B; Stambouli, M; Grossiord, J L

2009-07-25

386

Surfactant phospholipid metabolism.  

PubMed

Pulmonary surfactant is essential for life and is composed of a complex lipoprotein-like mixture that lines the inner surface of the lung to prevent alveolar collapse at the end of expiration. The molecular composition of surfactant depends on highly integrated and regulated processes involving its biosynthesis, remodeling, degradation, and intracellular trafficking. Despite its multicomponent composition, the study of surfactant phospholipid metabolism has focused on two predominant components, disaturated phosphatidylcholine that confers surface-tension lowering activities, and phosphatidylglycerol, recently implicated in innate immune defense. Future studies providing a better understanding of the molecular control and physiological relevance of minor surfactant lipid components are needed. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism. PMID:23026158

Agassandian, Marianna; Mallampalli, Rama K

2012-09-29

387

Surfactant-polymer interactions in enhanced oil recovery systems  

SciTech Connect

The nature and consequences of interactions between polyacrylamide and surfactant systems of interest in enhanced oil recovery have been investigated. Studies were done on systems with and without added oil and at low and high surfactant concentration. Polyacrylamide lowered the interfacial tension (IFT) of surfactant solutions by two to three orders of magnitude. The extent of IFT reduction was found to depend upon the charge on the polyacrylamide molecule, and on the polyacrylamide concentration. The polymer itself was not surface active and dialysis measurements revealed no binding between the surfactant and the polymer. Based on these observations a mechanism is proposed that can help explain the experimental findings. The transport of surfactant and polymer and their flow behavior in porous media were correlated with the phase behavior described above. Deviations from plug flow behavior are the least pronounced in the ..gamma.. phase region: there is minimal bypassing of the pore space by the polymer in this region. This correlation should be very useful in designing efficient mobility control buffers. A scheme is proposed for designing floods that are likely to minimize surfactant loss by phase entrapment due to surfactant-polymer interaction.

Desai, N.

1983-01-01

388

Polysaccharide gel with multiple emulsion  

Microsoft Academic Search

The aim of the present work was to investigate the possibility of using a semicrystalline oil phase in W\\/O\\/W to modify the release of encapsulated hydrophilic compounds from polysaccharide gels with embedded multiple emulsions.l-Tryptophan was enclosed within the W1-phase of an W1\\/O\\/W2-emulsion, which itself was homogeneously distributed in a Ca2+-alginate gel with maltodextrin (D.E. 6.5) as a bulking agent. Various

Julia Weiss; Inta Scherze; Gerald Muschiolik

2005-01-01

389

Formulating and stability of benzodiazepines in a new lipid emulsion formulation.  

PubMed

The objective of the current study was to evaluate the novelty of a new lipid emulsion formulation containing 30% oil phase as a drug delivery system. Therefore different benzodiazepines (BZs), namely diazepam, tetrazepam, clonazepam and lorazepam, were incorporated into this emulsion formulation. This lipid emulsion formulation showed enhanced solubilization capacity as 10 mg/ml, 10 mg/ml, 0.9 mg/ml, and 1.8 mg/ml formulations for diazepam, tetrazepam, clonazepam, and lorazepam were achieved, respectively. Incorporating the drugs into the lipid emulsion did not alter its physicochemical properties. Also the free and the drug emulsion formulations displayed good physical stability after autoclaving and after around one year of storage at shelf, as no changes in the physicochemical properties were observed. Most drugs also showed stable behavior after autoclaving and after approximately 1 year of storage at shelf. The only exception was lorazepam, as only around 50% of the drug was still intact after autoclaving. PMID:12611276

Jumaa, M; Müller, B W

2002-11-01

390

Rheological characterization of O/W emulsions incorporated with neutral and charged polysaccharides.  

PubMed

The effects of polysaccharides, including xyloglucan from Hymenaea courbaril (XG), galactomannans from Schizolobium parahybae (GMSP) and Mimosa scabrella (GMMS), xanthan gum (XT), sodium hyaluronate (HNa) and Fucogel(®) (FG), on the rheological behavior of cosmetic emulsions were evaluated. These incorporations gave rise to six emulsified systems, denoted XGE, GMSPE, GMMSE, XTE, HNaE and FGE, respectively. The emulsion consistency was found to follow the trend GMSPE>XGE>HNaE>FGE>XTE>GMMSE. In general, the addition of polysaccharides increased the viscoelastic properties of the emulsions and decreased the creep compliance. The neutral polysaccharides (GMSPE, GMMSE) led to better stability of the emulsions after storing for 20 days relative to charged polymers. It was found that polysaccharides XG, GMSP and GMMS, which come from the seeds of native Brazilian plant species, might be used to modify the flow properties and stabilities of oil-water emulsions. PMID:23465929

Vianna-Filho, Ricardo Padilha; Petkowicz, Carmen Lúcia Oliveira; Silveira, Joana Léa Meira

2012-05-17

391

Kenaf as a deep-bed filter medium to remove oil from oil-in-water emulsions  

SciTech Connect

This study investigated the feasibility of deep-bed filtration using kenaf (agricultural fiber) media for the removal of oil from oil-in-waste emulsions. Continuous flow, constant pressure filtrations were conducted using surfactant stabilized emulsions. Removal of oil and grease varied from 70 to 95% for 500 mg/L oil-in-water emulsion stabilized by surfactants. Oil removal was better for larger oil drops, finer media particles, higher filtration pressure, lower pH, cationic surfactant, and deeper media. Moisture contents and heating values of the spent media were determined. Moisture content decreased with increasing filtration pressure and decreasing particle size of the media. Heating values of the spent media increased with the volume of emulsion filtered. Heating values were high enough to produce surplus energy after accounting for the energy required for driving out the moisture. The results indicated that it may be possible to dispose of the spent medium by combustion without further drying and extract net energy in the process.

Varghese, B.K.; Cleveland, T.G. [Univ. of Houston, TX (United States)

1998-10-01

392

A practicable process for phenol removal with liquid surfactant membrane permeation column  

SciTech Connect

A practicable liquid surfactant membrane process for phenol removal is proposed with a stirred countercurrent column used as the liquid membrane contact equipment. The constituents of liquid membranes, such as internal aqueous phase and surfactant, the type of column, and the operating conditions for efficient and continuous performance of the liquid surfactant membrane process, have been examined. When NaOH solution was used as the internal aqueous phase and ECA4360J was used as the surfactant, the W/O emulsion was stable for the duration of column operation. More than 97% phenol could be removed from the feed solution. Nearly complete demulsification was also achieved by gentle agitation with an electrostatic demulsifier.

Kataoka, Takeshi; Osaki, Katsuhiko; Nishiki, Tadaaki [Osaka Prefecture Univ. (Japan)] [and others

1997-05-01

393

Stabilization of phase inversion temperature nanoemulsions by surfactant displacement.  

PubMed

Nanoemulsions are finding increasing utilization in the food and beverage industry to encapsulate and protect lipophilic functional components. Low-intensity methods, such as the phase inversion temperature (PIT) approach, are of particular interest for forming food-grade nanoemulsions because of their ease of formation and relatively low energy costs. Nevertheless, this type of emulsion tends to be highly unstable to droplet coalescence after preparation. In this study, we develop a potential solution to this problem using model water/surfactant (Brij 30, C(12)E(4))/oil (tetradecane) systems. The PIT and system morphology were determined by monitoring the temperature dependence of the electrical conductivity, turbidity, and microstructure of the emulsions. Nanoemulsions were formed by holding water/surfactant/oil mixtures at their PIT and then rapidly cooling them. The influence of storage temperature on emulsion stability was investigated, which indicated that the optimum temperature (13 degrees C) was about 27 degrees C lower than the PIT (approximately 40 degrees C). Higher storage temperatures resulted in an increase in droplet growth rate due to coalescence, while lower temperatures led to gelation. Nanoemulsions that were relatively stable to coalescence could be formed at ambient temperatures by adding either Tween 80 (0.2 wt %) or SDS (0.1 wt %) to displace the Brij 30 from the droplet surfaces. We propose that these surfactants increase nanoemulsion stability by changing the optimum curvature of the interfacial layer, as well as by increasing the repulsive interactions (steric or electrostatic) between the droplets. This study may lead to a novel approach to create stable nanoemulsion-based delivery systems that are suitable for utilization within the food industry. PMID:20476765

Rao, Jiajia; McClements, David Julian

2010-06-01

394

Linear viscoelasticity of emulsions. Part 1. The effect of an interfacial film on the dynamic viscosity of nondilute emulsions  

SciTech Connect

The dynamic viscosity of nondilute monodisperse emulsions is calculated by using a cell model. Two possibilities for describing the mechanical properties of the interfacial film between the internal and the external phase are considered: (a) the film is assigned a two-dimensional linear viscoelastic behavior and (b) the film is treated as a shell with finite thickness containing a Newtonian liquid. The resulting expressions for the dynamic viscosity show that model b has two relaxation times and model a has at least two or more. If a Voigt-Kelvin model is used to describe the interfacial rheology, model a will also have just two relaxation times. The results obtained may be used to interpret measurements on emulsions in terms of microscopic parameters of these emulsions. 23 references.

Oosterbroek, M.; Mellema, J.

1981-11-01

395

Nonideal detonation of Al-rich emulsion explosives  

Microsoft Academic Search

It is known that emulsion explosives have non-ideally in their detonation. The behavior of the non-ideal detonation has not yet been sufficiently investigated. In order to obtain a better comprehension of the non-ideal detonation behavior, optical measurements and measurements of the velocity of the detonation wave were carried out. Streak photographs were taken by an image converter camera using an

Shigeru Itoh; Katsuhiko Takahashi; Kenji Murata; Yukio Katoh; Akio Kira; Masaki Kojima; Masahiro Fujita

1997-01-01

396

Rheology of high internal phase emulsions.  

PubMed

The mechanical dispersion technology used in this study employs rotor-stator mixers that produce water-continuous high internal phase emulsions (HIPEs) with narrow drop size distributions and small drop sizes, even when the internal phase (oil) viscosity is quite high. Analysis of these HIPEs reveals trends that are consistent with formation by a capillary instability mechanism in which a shear deformation produces highly elongated drops that rupture to form uniform, small droplets. In the search for a predictive tool to aid in the manufacture and use of HIPEs, rheology data for these shear-thinning HIPEs have been compared to data for models in the literature. Existing models do not correctly account for the effect of a high internal phase viscosity on the rheological properties of the HIPE. Another shortcoming is failure to correctly address the shear-thinning exponent. Whereas internal phase viscosity does not seem to affect the shear-thinning exponent, the surfactant apparently plays an important role, possibly through its modification of the interfacial tension and continuous phase rheology. PMID:16460072

Welch, Cynthia F; Rose, Gene D; Malotky, David; Eckersley, Sarah T

2006-02-14

397

A Surface Force Study of Polymer-Surfactant Mixtures  

NASA Astrophysics Data System (ADS)

We study the interactions between a cationic modified guar and Sodium Dodecyl Sulfate (SDS). The bulk properties have been investigated by rheology and spectrofluorimetry. A Surface Force Apparatus (SFA) was used to determine the structure of the adsorbed polymer-surfactant layer. The bulk behavior is typical of a polymer-surfactant solution where the polymer and the surfactant bear opposite charges. For low enough SDS concentrations, the surfactant and the polymer mix in a single phase. A two phase region is reached at charge equivalence and redissolution of a very low viscosity solution by charge inversion is observed for higher SDS concentrations. At the mica surface, the cationic polymer adsorbs in a configuration with thickness of the order of 250 nm. When SDS is added, the change in both the layer thickness and the forces profile indicate a strong structural modification upon increasing surfactant concentration of the adsorbed layer.

Marques, Carlos; Anthony, O.; Richetti, P.

1997-03-01

398

Solubility and aggregation of charged surfactants in ionic liquids.  

PubMed

Room-temperature ionic liquids (ILs) exhibit a unique set of properties, leading to opportunities for numerous applications. To obtain a better understanding of IL interfaces at a molecular level, we combined charged surfactants with ILs and studied their interfacial behavior. The critical micelle concentration (cmc) of each surfactant-IL pair was determined from both solubility phase diagrams and isotherms. Because the cmc is equivalent to the solubility at the Krafft temperature, a connection between the solubility of the surfactant and the physical properties of the underlying ionic liquid was established. Interfacial energy was found to be the major factor affecting the surfactant aggregation process, although its magnitude depends strongly on the IL structure. The results here give insight into explaining the nature of self-assembly of surfactants at IL interfaces and the interaction between solutes and IL solvents. PMID:22168452

Chen, Lang G; Bermudez, Harry

2012-01-05

399

Aggregation behavior of sodium dioctylsulfosuccinate in aqueous ethylene glycol medium. A case of hydrogen bonding between surfactant and solvent and its manifestation in the surface tension isotherm.  

PubMed

The dependence of critical micelle concentration (cmc) of sodium dioctylsulfosuccinate (AOT) on the amount of ethylene glycol (EG) in water + EG medium was reported to be unusual and different from that of other surfactants to the extent that the cmc of AOT in EG is lower than in water. It is yet to be understood why AOT behaves so in water + EG medium, although AOT is known to have some special properties. Hence in the present study cmc of AOT in water + EG medium in the range from 0 to 100% (by weight) EG is measured by using surface tension and fluorescence emission methods. In contrast to what was reported, this study revealed that with respect to EG amount the cmc of AOT follows the general trend and AOT has higher cmc in EG than in water. On the other hand, it was surprisingly found that a break in the surface tension isotherm occurs in the premicellar region when the amount of EG exceeds 50% rendering a bisigmoidal shape to the surface tension isotherm. UV spectral study showed that AOT and EG undergo hydrogen bonding in the premicellar region when the EG amount is ?50% and this hydrogen bonding becomes less on adding NaCl. The density functional theory calculations also showed formation of hydrogen bonds between EG and AOT through the sulfonate group of AOT providing thereby support to the experimental findings. The calculations predicted a highly stable AOT-EG-H(2)O trimer complex with a binding energy of -37.93 kcal mol(-1). The present system is an example, which is first of its kind, of a case where hydrogen bonding with surfactant and solvent molecules results in a surface tension break. PMID:23072621

Das, D; Dey, J; Chandra, A K; Thapa, U; Ismail, K

2012-11-02

400

Testing of Fat Emulsions for Toxicity. III. Toxicity Studies with New Fat Emulsions and Emulsion Components.  

National Technical Information Service (NTIS)

Extensive studies were conducted at four separate laboratories to evaluate the chemical and physical properties, and the biological effects of two fat emulsions: Intralipid (20 per cent) and Lipofundin (15 per cent). In addition, a variety of experimental...

S. W. Thompson L. D. Jones J. F. Ferrell R. D. Hunt H. C. Meng

1965-01-01

401

Preparation of polymeric nanoparticles using a new polymerizable surfactant  

NASA Astrophysics Data System (ADS)

A novel polymerizable surfactant (so-called surfmer) was synthesized and characterized according to its structure, surface activity and polymerization ability. Polymeric micelles (size of 6 and 130 nm) appeared in the polyreaction initiated by free radicals from VA-044. In the presence of the monomer (i.e., methyl methacrylate) microemulsion systems were formed that in turn were transformed into latex entities (size — 40 nm). Additionally, an emulsion polymerization was performed with the use of n-hexadecane as an oil phase resulting in the production of nanocapsules (size in the range — 165-220 nm). The shape and morphologies of the nanoobjects were confirmed using Atomic Force Microscopy (AFM).

Bunio, Paulina; Zieli?ska, Katarzyna; Chlebicki, Jan; Wilk, Kazimiera A.

2011-04-01

402

Development of a novel parenteral formulation for tetrazepam using a lipid emulsion.  

PubMed

A novel parenteral formulation for tetrazepam (10 mg/ml) was developed using lipid emulsions. This formulation utilized a new lipid emulsion formulation, which was developed by changing the polarity of the oil phase. It was found that increasing the polarity of the oil phase resulted in enhanced solubility of tetrazepam. Tetrazepam showed higher solubility in a mixture of castor oil and middle-chain triglycerides (MCTs) (1:1) than in any other oil investigated. This mixture resulted in low interfacial tension and moderate viscosity, which seemed to be the optimum oil phase. In addition, to increase the concentration of tetrazepam, an emulsion formulation containing 30% oil phase was produced and optimized. The drug-free emulsion formulation showed fine particle sizes with an imperceptible change in physicochemical properties after more than 2 years on the shelf. As a result, it was possible to produce a parenteral emulsion formulation containing 10 mg/ml tetrazepam. No change in the physicochemical properties of the emulsion was observed after the addition of tetrazepam. The tetrazepam emulsion showed stable behavior during the autoclaving process and good shelf stability for at least 10 months as well. Tetrazepam itself also displayed good stability during the autoclaving process and also showed good shelf stability in this emulsion formulation. PMID:11794814

Jumaa, M; Müller, B W

2001-11-01

403

Choline alkylsulfates--new promising green surfactants.  

PubMed

In this work we show how a new promising green and highly water-soluble surfactant can be designed based on recent progress in the knowledge of counterion-headgroup binding and crystallization behavior. The result is the combination of a most classical surfactant anion, dodecylsulfate (DS), with choline (Ch), a natural green cation. The advantage of the physiological metabolite choline is its bulky structure that prevents ChDS from easy crystallization and thus leads to a considerable lowering of the Krafft point down to 0°C. The counterion-headgroup binding is reflected by the aqueous phase behavior of ChDS. Conductivity, surface tension, and cryo-TEM measurements allow the characterization of the dilute micellar region, while the penetration scan technique enables the establishment of a preliminary aqueous phase diagram. In addition, the influence of different mono- and divalent salts on the solubility of ChDS is investigated. The results are compared to the alkali sulfate and alkylcarboxylate homologs, and reveal that ChDS is less sensitive towards addition of salts than, for instance, choline carboxylates due to an increased counterion-headgroup association. Further, cytotoxicity tests on HeLa and SK-Mel 28 cells are presented and compared to other surfactants, showing that ChDS is no more harmful than its sodium counterpart SDS. Taken together, our findings highlight that the harmless green cation choline is of great potential for the design of new surfactants. PMID:23200100

Klein, Regina; Kellermeier, Matthias; Touraud, Didier; Müller, Eva; Kunz, Werner

2012-10-16

404

Nucleate pool boiling heat transfer in aqueous surfactant solutions  

NASA Astrophysics Data System (ADS)

Saturated, nucleate pool boiling in aqueous surfactant solutions is investigated experimentally. Also, the role of Marangoni convection, driven both by temperature and surfactant concentration gradients at the vapor-liquid interface of a nucleating bubble is computationally explored. Experimental measurements of dynamic and equilibrium sigma using the maximum bubble pressure method indicate dynamic sigma to be higher than the corresponding equilibrium value, both at room and elevated temperatures. Also, nonionic surfactants (Triton X-100, Triton X-305) show larger sigma depression than anionic surfactants (SDS, SLES), and a normalized representation of their dynamic adsorption isotherms is shown to be helpful in generalizing the surfactant effectiveness to reduce surface tension. The dynamic sigma has a primary role in the modification of bubble dynamics and associated heat transfer, and is dictated by the adsorption kinetics of the surfactant molecules at boiling temperatures. In general, an enhancement in heat transfer is observed, which is characterized by an early incipience and an optimum boiling performance at or around the critical micelle concentration of the surfactant. The optimum performances, typically in the fully developed boiling regime ( q''w > 100 kW/m2), show a reverse trend with respect to surfactant molecular weights M, i.e., higher molecular weight additives promote lower enhancement. Normalized boiling performance using the respective solution's dynamic sigma correlates heat transfer coefficient by M-0.5 for anionics and M 0 for nonionics. This has been shown to be brought about by the surfactant concentration and its interfacial activity in a concentration sublayer around the growing vapor bubble, which governs the bubble growth behavior through the mechanism of dynamic sigma. The ionic nature of the surfactant influences the thickness and molecular makeup of the enveloping sublayer, thereby affecting the bubble dynamics and boiling heat transfer. Finally, the computational modeling of Marangoni convection for boiling nuclei at short time transients shows similarity solutions for pure water, and reduced convection with a peak in circulation strength in the presence of surfactants. The peaking corresponds to the characteristic surfactant adsorption time, which has been shown to depend solely upon the surfactant bulk concentration. For the absence of surfactant surface convection, an enhancement in Marangoni convection is observed. Furthermore, for the investigated range of parameters and time scales, the surfactant adsorption at the interface is not characterized by the presence of a stagnant cap. (Abstract shortened by UMI.)

Wasekar, Vivek Mahadeorao

405

Measurement of emulsion flow in porous media: Improvements in heavy oil recovery  

NASA Astrophysics Data System (ADS)

Many heavy oil and bitumen reservoirs in the world are too small or thin for thermal enhanced oil recovery methods to be economic. In these fields, novel methods of less energy intensive, non-thermal technologies are required. Previous experience has shown that the injection of low concentrations of aqueous alkali-surfactant solutions into the reservoir can significantly improve the oil recovery, beyond that of waterflooding. This is due to the in-situ formation of emulsions, which plug off the water channels and lead to improved sweep efficiency in the reservoir. The proper control of these floods requires methods for monitoring the formation and effect of these emulsions. In this paper, the results of laboratory core floods are interpreted to demonstrate how the pressure and flow response can be related to the formation of these emulsions. A new technique (low field NMR) is also used to directly measure W/O emulsions in porous media. Finally, a numerical study is performed in order to demonstrate how the in-situ formation of emulsions can be simply represented in simulation software.

Bryan, J.; Wang, J.; Kantzas, A.

2009-02-01

406

Food grade duplex emulsions designed and stabilised with different osmotic pressures.  

PubMed

In this study we have investigated the production of food grade W(1)/O/W(2) duplex emulsions with salt partitioned into one water phase but not the other. Investigations were carried out with and without balancing osmotic pressures with glucose. A stable 30% primary W(1)/O emulsions containing salt could be produced with more than or equal to 2% polyglycerol polyricinoleate (PGPR) in the oil phase. We suggest that the addition of salt strengthens the interactions between surfactant molecules in the adsorbed film. This is supported by interfacial viscosity and elasticity measurements both of which increased on addition of salt and the fact that in the presence of salt the emulsion was more stable. These simple emulsions were then processed to construct duplex emulsions. When osmotic pressures were balanced with glucose there was still a release of salt in storage. The extent and rate of release was proportional to glucose concentration. This effect was followed over a period of 60days. These data suggest that the release is driven by the chemical potential difference between the two water compartments rather than the unbalanced osmotic pressures. These observations are explained in the context of a water structuring effect from the added glucose, which lowers the interfacial tension of oil-water interface and thus facilitates micellar transport of hydrated salt ions across the oil layer. PMID:20828706

Pawlik, Aleksandra; Cox, Philip W; Norton, Ian T

2010-08-21

407

“One pot” synthesis of fluorinated block copolymers using a surface-active ATRP initiator under emulsion polymerization conditions  

Microsoft Academic Search

Three fluorinated block copolymers have been prepared successfully in emulsion system using a surface-active atom transfer\\u000a radical polymerization (ATRP) initiator disodium 4-(10-(2-bromo-2-methylpropanoyloxy)decyloxy)-4-oxo-2-sulfonatobutanoate\\u000a (1). The copolymerization can be conducted in “one pot” under activator generated by electron transfer (AGET) ATRP in emulsion\\u000a conditions, thus greatly simplifying the operations and workup. The anionic surface-active ATRP initiator (1) and nonionic surfactant OP-10 may

Jinbing ShuChuanjie; Chuanjie Cheng; Yi Zheng; Liang Shen; Yongluo Qiao; Changqing Fu

408

Preparation of polyepoxide microcapsule via interfacial polyaddition reaction in W\\/O and O\\/W emulsion systems  

Microsoft Academic Search

The interfacial polyaddition reaction between the oil-soluble ethyleneglycol diglycidylether (EGDGE) and the water-soluble hexamethylene diamine (HMDA) and\\/or diethylene triamine (DETA) was carried out in a water-in-oil (W\\/O) and an oil-in-water (O\\/W) emulsion to obtain polyepoxide-amine microcapsules. The microcapsules obtained from the W\\/O emulsion using tetraglycerol monooleate (MO-310, HLB 8.8) as an oil phase (cyclohexane: toluene 185:15 v\\/v) surfactant were around

Naohiro Yamazaki; Yong-Zhong Du; Masatoshi Nagai; Shinzo Omi

2003-01-01

409

Separation and concentration of gallium from acidic leach solutions containing various metal ions by emulsion type of liquid membranes using TOPO as mobile carrier  

Microsoft Academic Search

The separation and concentration of gallium from acidic leach solutions, containing various other ions, such as iron, cobalt, nickel, zinc, cadmium, lead, copper, and aluminium, by an emulsion liquid membrane (ELM) technique using trioctylphosphine oxide (TOPO) as carrier has been presented. Liquid membrane consists of a diluent, a surfactant (ECA 4360J), and an extractant (TOPO), and 0.1 M HCl or

R. A. Kumbasar; O. Tutkun

2004-01-01

410

Separation of cobalt and nickel from acidic leach solutions by emulsion liquid membranes using Alamine 300 (TOA) as a mobile carrier  

Microsoft Academic Search

An emulsion liquid membrane process using tri-n-octylamine (Alamine 300) to extract and separate cobalt from the acidic leach solutions has been presented. Liquid membrane consists of a diluent, a surfactant (ECA 4360J), and an extractant (Alamine 300, Cognis Corp.). Ammonia solutions have been used as the stripping solution. The important parameters governing the permeation of cobalt and their effect on

Recep Ali Kumbasar; Osman Tutkun

2008-01-01

411

Wettability of Freon hydrates in crude oil/brine emulsions.  

PubMed

The surface energy of petroleum hydrates is believed to be a key parameter with regard to hydrate morphology and plugging tendency in petroleum production. As of today, the surface energy of natural gas hydrates is unknown, but will depend on the fluids in which they grow. In this work, the wettability of Freon hydrates is evaluated from their behavior in crude oil emulsions. For emulsions stabilized by colloidal particles, the particle wettability is a governing parameter for the emulsion behavior. The transition between continuous and dispersed phases as a function of brine volume in crude oil-brine emulsions containing Freon hydrates has been determined for 12 crude oils. Silica particles are used for comparison. The results show that phase inversion is highly dependent on crude oil properties. Based on the measured points of phase inversion, the wettability of the Freon hydrates generated in each system is evaluated as being oil-wet, intermediate-wet, or water-wet. Generation of oil-wet hydrates correlates with low hydrate plugging tendency. The formation of oil-wet hydrates will prevent agglomeration into large hydrate aggregates and plugs. Hence, it is believed that the method is applicable for differentiating oils with regard to hydrate morphology. PMID:15914170

Høiland, S; Askvik, K M; Fotland, P; Alagic, E; Barth, T; Fadnes, F

2005-07-01

412

In vitro studies on the application of colloidal emulsion aphrons to drug overdose treatment.  

PubMed

Colloidal emulsion aphrons (CEAs) are considered as the micron-sized water-in-oil (W/O) emulsion-cores encapsulated by a "soapy shell" consisting of multi-layer surfactant molecules. In this dispersion, the emulsion-core sizes are mainly in 10-100 microm and that of the inner phase droplets are in 1-5 microm. CEAs not only behave analogously to emulsion liquid membrane (ELM) in extraction with advantages of high concentration ratio, counter-concentration extraction and combination of extraction with backwash together, but also have the large interface areas, easy scatteration and quick extraction which colloidal liquid aphrons (CLAs) possess. CEA extraction overcomes the restriction of partition equilibrium between the water and the oil phase that CLAs have. They have greater extraction capacity than CLAs. In this study, the application of CEAs to drug overdose treatment was studied using salicylic acid as the model drug, paraffin oil as the membrane phase, PEG-30 dipolyhydroxystearate (P135) as the hydrophobic surfactant, nonylphenol ethoxylate-10 (NP10) as the hydrophilic surfactant and NaOH solution as the receptor phase. Also some factors affecting the stability of this dispersion and extraction ratio were investigated. In order to prepare CEAs successfully, the concentrations of NP10 and P135 should be in 1.5-3.0% (w/v) and 0.25-1.0% (w/v), respectively, together with the ratio of the volume of oil phase to the volume of inner aqueous phase of CEAs, R(oi)> or =1:1. For the extraction of salicylic acid, the pH value of the feed phase was supposed to be lower than 2.0 and the suitable NaOH concentration of the receptor phase was higher than 0.02 mol/L. Under this condition, more than 98.7% of salicylic acid was transported into receptor phase in half a minute. PMID:16439075

Dai, Yujie; Deng, Tong; Lu, Fuping

2006-01-24

413

Chemical Demulsification of Tanker Crude Emulsions.  

National Technical Information Service (NTIS)

The chemical demulsification of tanker crude emulsions was studied as a function of oil type (light vs. heavy crude), demulsifier concentrations, and temperature. Aerosol OT shows promise as a chemical demulsifier of tanker crude emulsions provided that a...

R. C. Little

1980-01-01

414

Three-component microemulsions formed using pH-degradable 1,3-dioxolane alkyl ethoxylate surfactants  

Microsoft Academic Search

A series of three nonionic surfactants which undergo acid-catalyzed hydrolysis, O-[(2,2-dialkyl-1,3-dioxolan-4-yl) methoxy] –O?-methoxy poly(ethylene glycol), or cyclic ketal (CK), were synthesized. The surfactants shared similar HLB values (9.2–9.8) but differed in the relative length of their two alkyl tails. Water\\/CK\\/isooctane microemulsion systems formed by each of the three surfactants also shared similar phase behavior, physical properties, and surfactant hydrolysis kinetics.

Maithili E. Rairkar; M. Elena Diaz; Mauro Torriggiani; Ramon L. Cerro; J. Milton Harris; Sarah E. Rogers; Julian Eastoe; Javier A. Gomez del Rio; Douglas G. Hayes

2007-01-01

415

Water-Soluble Fluorochemical Surfactant Well Stimulation Additives  

Microsoft Academic Search

Water-soluble fluorochemical surfactants have been used in the oil field since the early 1970's as surface tension depressants in a variety of aqueous stimulation fluids for low-permeability oil and gas wells. This paper discusses a laboratory study of the behavior of water-soluble fluorochemical surfactants relative to their oil field use. Data are presented on surface tension depression, thermal stability, adsorption,

Henry Clark; Myron Pike; Gayle Rengel

1982-01-01

416

Synthesis and Physicochemical Investigation of Long Alkylchain Betaine Zwitterionic Surfactant  

Microsoft Academic Search

An effective and economic two-step route was developed to synthesize the long alkyl chain betaine zwitterionic surfactant\\u000a directly from natural fatty acids. The optimal processing conditions for synthesizing the intermediate and final product were\\u000a probed and the yields of 96.4% and 88.3% were obtained for each step, respectively. The surface active behavior of the synthesized\\u000a decylbetaine surfactant was investigated using

Liyun Qi; Yun Fang; Zeyun Wang; Na Ma; Liangyu Jiang; Yiyou Wang

2008-01-01

417

Surfactant waterflooding oil recovery method  

SciTech Connect

Disclosed is a novel surfactant fluid and an oil recovery method using the fluid for recovering oil from subterranean formations thereof by surfactant waterflooding process. The fluid comprises an alkylpolyalkoxyalkylene sulfonate or an alkylarylpolyalkoxyalkylene sulfonate and a stabilizing agent comprising a synergistic mixture of an alkanol and an alkyl phenol. The presence of the mixture of alkanol and phenol improves the phase stability of the fluid, increases the viscosity of the surfactant fluid, and reduces the adsorption of surfactant by the formation.

Kalfoglou, G.

1980-11-04

418

Effect of surfactant surface coverage on formation of solid lipid nanoparticles (SLN)  

Microsoft Academic Search

The effect of surfactant surface coverage on formation and stability of Tween 20 stabilized tripalmitin solid lipid nanoparticles (SLN) was investigated. A lipid phase (10% w\\/w tripalmitin) and an aqueous phase (2% w\\/w Tween 20, 10mM phosphate buffer, pH 7) were heated to 75°C and then homogenized using a microfluidizer. The resulting oil-in-water emulsion was kept at a temperature (37°C)

T. Helgason; T. S. Awad; K. Kristbergsson; D. J. McClements; J. Weiss

2009-01-01

419

Surfactant Metabolism in the Neonate  

Microsoft Academic Search

With the use of stable isotope-labeled intravenous precursors for surfactant phosphatidylcholine (PC) synthesis, it has been shown that the de novo synthesis rates in preterm infants with respiratory distress syndrome (RDS) are very low as are turnover rates. This is consistent with animal data. Surfactant therapy does not inhibit endogenous surfactant synthesis, and prenatal corticosteroids stimulate it. With the use

L. J. I. Zimmermann; D. J. M. T. Janssen; D. Tibboel; A. Hamvas; V. P. Carnielli

2005-01-01

420

Effect of demulsifier partitioning on the destabilization of water-in-oil emulsions  

Microsoft Academic Search

The factors affecting the demulsification and interfacial behavior of water-in-oil emulsions in the presence of oil-soluble demulsifiers were investigated. Using both model water-in-oil and water-in-crude oil emulsion systems with demulsifiers with different chemical structures, the effects of demulsifier partitioning on the interfacial and film rheological properties were studied. The experimental results were compared and related with the demulsifier performance. There

Young H. Kim; Darsh T. Wasan

1996-01-01

421

Micellar evolution in mixed nonionic/anionic surfactant systems.  

PubMed

Surfactant mixtures are widely used in industrial applications due to their favorable synergistic interactions. For instance, anionic and nonionic mixtures are often employed in detergent, personal care, and enhanced oil recovery. It is useful to understand micellization behaviors of such mixtures, as they are important for formulation optimizations. A range of techniques including surface tensiometry, fluorescence spectroscopy, ultrafiltration, and analytical ultracentrifugation (AUC), were employed in this work to obtain information on the micellization behaviors of the mixed n-dodecyl-?-D-maltoside (DM)/sodium dodecyl sulfonate (SDSN) system. The interaction parameter, monomer concentration, and micellar size and shape distribution were obtained for this mixed surfactant system as a function of total surfactant concentration as well as mixing ratio to achieve a full understanding of their aggregation behaviors. The coexistence of two types of micelles was identified in this mixed anionic/nonionic surfactant system for the first time. A model is proposed to explain such coexistence based on the surface activities and the interactions between the two types of surfactants. These findings are useful for optimizing the composition of mixed surfactant systems and enhancing the synergetic efficiency of the system to achieve more effective and economical formulations. PMID:22115159

Lu, Shaohua; Wu, Jun; Somasundaran, Ponisseril

2011-11-07

422

Solution properties and emulsification properties of amino Acid-based gemini surfactants derived from cysteine.  

PubMed

Amino acid-based anionic gemini surfactants (2CndiCys, where n represents an alkyl chain with a length of 10, 12, or 14 carbons and "di" and "Cys" indicate adipoyl and cysteine, respectively) were synthesized using the amino acid cysteine. Biodegradability, equilibrium surface tension, and dynamic light scattering were used to characterize the properties of gemini surfactants. Additionally, the effects of alkyl chain length, number of chains, and structure on these properties were evaluated by comparing previously reported gemini surfactants derived from cystine (2CnCys) and monomeric surfactants (CnCys). 2CndiCys shows relatively higher biodegradability than does CnCys and previously reported sugar-based gemini surfactants. Both critical micelle concentration (CMC) and surface tension decrease when alkyl chain length is increased from 10 to 12, while a further increase in chain length to 14 results in increased CMC and surface tension. This indicates that long-chain gemini surfactants have a decreased aggregation tendency due to the steric hindrance of the bulky spacer as well as premicelle formation at concentrations below the CMC and are poorly packed at the air/water interface. Formation of micelles (measuring 2 to 5 nm in solution) from 2CndiCys shows no dependence on alkyl chain length. Further, shaking the mixtures of aqueous 2CndiCys surfactant solutions and squalane results in the formation of oil-in-water type emulsions. The highly stable emulsions are formed using 2C12diCys or 2C14diCys solution and squalane in a 1:1 or 2:1 volume ratio. PMID:23985487

Yoshimura, Tomokazu; Sakato, Ayako; Esumi, Kunio

2013-01-01

423

Thermodynamics of carbohydrate surfactant containing systems  

Microsoft Academic Search

The skillful combination of carbohydrate surfactant–water–oily component–cosurfactant is successful in obtaining microemulsion states for the solubilization of comparable amounts of materials as dissimilar as oil and water into a single, thermodynamically stable, liquid phase.This paper focused on theoretical study of the phase behavior of the corresponding binary and ternary subsystems and the quaternary system. The phase equilibrium calculations based on

Heike Kahl; Sabine Enders

2002-01-01

424

Transdermal Delivery of an Anti-Cancer Drug via W\\/O Emulsions Based on Alkyl Polyglycosides and Lecithin: Design, Characterization, and In Vivo Evaluation of the Possible Irritation Potential in Rats  

Microsoft Academic Search

The purpose of this work was to develop w\\/o emulsions that could be safely used to promote transdermal delivery of 5-fluorouracil\\u000a (5-FU). Two pseudo-ternary phase diagrams comprising oleoyl-macrogol glycerides, water, and a surfactant\\/co-surfactant (S\\/CoS)\\u000a mixture of lecithin, ethanol, and either coco glucoside or decyl glucoside were investigated for their potential to develop\\u000a promising 5-FU emulsions. Six systems were selected and

Aliaa Nabil ElMeshad; Mina Ibrahim Tadros

2011-01-01

425

High purity nanolatex prepared by ultrasonically irradiated emulsion polymerization.  

PubMed

Ultrasonically initiated emulsion copolymerization of styrene and a cationic polymerizable surfactant (methacryloxyethyl dodecydimethyl ammonium bromide, C(12)N(+)) was successfully employed to prepare high purity copolymer nanolatex. C(12)N(+) can play the roles of an emulsifier, an initiator, and a comonomer at the same time. It has an excellent initiation efficiency and reactivity. The rate of copolymerization was high and styrene conversion achieved 95% in an hour. Nanoscale latex particles with average diameter 40 nm were obtained easily under ultrasonic irradiation. Results of FTIR, (1)H NMR and surface tension tests proved almost all surfmers had copolymerized with styrene when the C(12)N(+) concentration was more than 0.030 g/mL, indicating high purity nanolatex without residual emulsifiers was obtained. PMID:17602850

Zheng, Yuanyuan; Cao, Ya; Pan, Guangqin

2007-05-13

426

Analysis, Development and Investigations into Phase Behavior of Surfactant Systems for De-Oiling High-Salinitiy Reservoirs with Reference to the Bockstedt Field of Wintershall AG. Final Report.  

National Technical Information Service (NTIS)

To achieve close cooperation between surfactant analysis, surfactant synthesis and phase investigations, R and D-projects 03E-6123 B and 03E-6123 C were run as team projects by BASF and Wintershall. The development of new analytical methods enabled non-io...

G. Krusche N. Greif E. Lessner

1988-01-01

427

Surfactant waterflooding oil recovery method  

SciTech Connect

Disclosed is a novel surfactant fluid and an oil recovery method using the fluid for recovering oil from subterranean formations thereof by surfactant waterflooding process. The fluid comprises water and at least one surfactant, preferably including an alkylpolyalkoxyalkylene sulfonate or an alkylarylpolyalkoxyalkylene sulfonate and as an additive for reducing the rigidity of the interfacial film, a silicapolydialkylsiloxane such as a silica-polydimethylsiloxane. Reduction in rididity of the interfacial film occupied by surfactant molecules of which the hydrophobic portion is dissolved in the oil phase and the hydrophilic portion is dissolved in the aqueous phase, improves the effectiveness of the surfactant fluid for recovering oil from subterranean formations.

Kalfoglou, G.

1981-10-27

428

Surfactant oil recovery process  

Microsoft Academic Search

Surfactant oil recovery process is claimed in which an aqueous fluid containing petroleum sulfonate is injected into an oil formation containing water which is naturally fresh or which has been reduced to an acceptable salinity level by a pre-flush with fresh water is disclosed. Optimum oil recovery is achieved by determining the average equivalent weight petroleum sulfonate which produces the

J. T. Carlin; J. H. Park

1978-01-01

429

Surfactant-enhanced bioremediation  

SciTech Connect

This study was undertaken to examine the effect of three structurally related, non-ionic surfactants, Triton X-45, Triton X-100 and Triton X-165, as well as the oleophilic fertilizer, Inipol EAP 22, on the rate of biodegradation of phenanthrene by pure bacterial cultures. Each surfactant dramatically increased the apparent aqueous solubility of phenanthrene. Model studies were conducted to investigate the ability of these surfactants to enhance the rate of transport and uptake of polycyclic aromatic hydrocarbons into bacterial cells, and to assess the impact that increasing the aqueous solubility of hydrocarbons has on their rate of biodegradation. The results indicate that increasing the apparent aqueous solubility of hydrocarbons can lead to enhanced biodegradation rates by two Pseudomonas saccharophila strains. However, the experiments also suggest that some surfactants can inhibit aromatic hydrocarbon biodegradation by certain bacteria. The data also support the hypothesis that surface-active components present in the oleophilic fertilizer formulation, Inipol EAP 22, may have significantly contributed to the positive results reported in tests of remedial agent impact on bioremediation, which was used as a supplemental clean-up technology on Exxon Valdez crude oil-contaminated Alaskan beaches.

Churchill, P.F.; Dudley, R.J.; Churchill, S.A. [Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Biological Sciences

1995-12-31

430

SURFACTANTS AND SUBSURFACE REMEDIATION  

EPA Science Inventory

Because of the limitations of pump-and-treat technology, attention is now focused on the feasibility of surfactant use to increase its efficiency. urfactants have been studied for use in soil washing and enhanced oil recovery. lthough similarities exist between the applications, ...

431

Extraction of Co(II) from aqueous solution using emulsion liquid membrane.  

PubMed

The extraction equilibrium of Co(II) from thiocyanate medium by CYANEX 923 (mixture of straight chain alkylated phosphine oxides) in cyclohexane was studied. The stoichiometry of the extraction reaction was postulated based on slope analysis method and the extraction constant Kex was calculated. The stripping percentage of Co(II) with sulphuric acid from the loaded CYANEX 923 was found to increase with the increase in acid concentration. The extraction of Co(II) from aqueous thiocyanate medium into emulsion liquid membrane using CYANEX 923 extractant was also studied. The influence of different parameters such as stirring speed, surfactant concentration, pH of the extractant phase, carrier concentration, internal phase stripping acid concentration, initial Co(II) concentration as well as temperature on the emulsion stability were investigated. The applicability of the emulsion liquid membrane (ELM) process using CYANEX 923 as extractant and SPAN 80 as surfactant for the removal and the concentration of Co(II) from thiocyanate solution was investigated. The results show that it is possible to recover 95% of cobalt in the inner phase after 10 min of contacting time with a concentration factor of 5. PMID:17658686

Gasser, M S; El-Hefny, N E; Daoud, J A

2007-06-14

432

Novel synthesis of macroporous poly(N-isopropylacrylamide) hydrogels using oil-in-water emulsions.  

PubMed

Porous N-isopropylacrylamide (NIPA) hydrogels having a unique structure, that is, spherelike cavities distributed randomly and a homogeneous network in the gel phase, were successfully synthesized by means of an emulsion templating method; this method involves the synthesis of NIPA gels in an oil-in-water (O/W) emulsion by free radical copolymerization with a cross-linker, followed by washing (removal) of the dispersed oil as a pore template (porogen). The synthesis conditions, O/W volume ratio, amount of added surfactant, and monomer concentration affect the internal pore structure, equilibrium swelling, and swelling/shrinking kinetics. A porous hydrogel swollen at 10 degrees C has a pore diameter distribution in the range of 1-40 microm, which was observed with a scanning electron microscope. Scanning electron micrographs and swelling degree reveal that the pore size and porosity can be adjusted by varying the O/W volume ratios and surfactant amounts. The porous hydrogels show very rapid swelling/shrinking in accordance with the temperature swing. The fast response is attributed to the convection flow of water through the macropores. In addition to a faster response gel, the emulsion templating method can yield potentially intelligent gels in which the pores function as spaces for reaction, separation, and storage. PMID:17880115

Tokuyama, Hideaki; Kanehara, Akifumi

2007-09-19

433

Amphotericin B and pulmonary surfactant.  

PubMed

Targeted intrapulmonary delivery of drugs may reduce systemic toxicity, improve treatment efficacy, but inhaled drugs may also interfere with pulmonary surfactant function. We hypothesized that the lipophilic drug amphotericin B used to treat or prevent pulmonary infections with aspergillus species, might destroy surface activity of lung surfactant, as assessed in a pulsating bubble surfactometer. Pure amphotericin B had no effect on a natural surfactant preparation or on the lipid extracted surfactant SurvantaTM. However, amphotericin BTM (containing deoxycholic acid) or deoxycholic acid alone inhibited surfactant surface activity dose dependently and perturbed lipid organization. AmbisomeTM containing amphotericin B associated with liposomes, only marginally affected surfactant function. Intrapulmonary delivery of large amounts of amphotericin BTM has to consider the potential of interferences with lung surfactant function. PMID:9707520

Griese, M; Schams, A; Lohmeier, K P

1998-08-18

434

Surfactant mediated charging of polymer particles in a nonpolar liquid.  

PubMed

We study the charging behavior of polystyrene and polymethyl methacrylate particles with different functional surface groups in water and in decane containing either ionic (AOT) or nonionic surfactant (Span 85). Electrophoretic mobilities in the nonpolar media are measured as a function of surfactant concentration and the applied electric field strength by phase analysis light scattering (PALS); acid-base characteristics of the particles and the surfactant are investigated via contact angle measurement and interfacial tensiometry, and the residual water content of the non-aqueous dispersions is assessed by Karl Fischer titration. The results suggest a competition of several mechanisms for particle charging in nonpolar media. At high concentrations of the nonionic surfactant, particle charging becomes insensitive to the functional surface groups responsible for charging in aqueous dispersions, but consistent with a charge transfer between the polymer surface and the surfactant due to acid-base interactions, which can be rationalized in terms of measurable acid-base parameters. By contrast, particle charging in nonpolar solutions of the ionic surfactant (with significantly larger amounts of residual water) suggests a strong influence of surface headgroup ionization, and of dissociated surfactants adsorbed to the particle surface. PMID:23142011

Guo, Qiong; Lee, Joohyung; Singh, Virendra; Behrens, Sven H

2012-10-22

435

Pickering emulsions stabilized by cellulose nanocrystals grafted with thermo-responsive polymer brushes.  

PubMed

Cellulose nanocrystals (CNCs) from ramie fibers are studied as stabilizers of oil-in-water emulsions. The phase behavior of heptane and water systems is studied, and emulsions stabilized by CNCs are analyzed by using drop sizing (light scattering) and optical, scanning, and freeze-fracture electron microscopies. Water-continuous Pickering emulsions are produced with cellulose nanocrystals (0.05-0.5 wt%) grafted with thermo-responsive poly(NIPAM) brushes (poly(NIPAM)-g-CNCs). They are observed to be stable during the time of observation of 4 months. In contrast, unmodified CNCs are unable to stabilize heptane-in-water emulsions. After emulsification, poly(NIPAM)-g-CNCs are observed to form aligned, layered structures at the oil-water interface. The emulsions stabilized by poly(NIPAM)-g-CNCs break after heating at a temperature above the LCST of poly(NIPAM), which is taken as indication of the temperature responsiveness of the brushes installed on the particles and thus the responsiveness of the Pickering emulsions. This phenomenon is further elucidated via rheological measurements, in which viscosities of the Pickering emulsions increase on approach of the low critical solution temperature of poly(NIPAM). The effect of temperature can be counterbalanced with the addition of salt which is explained by the reduction of electrostatic and steric interactions of poly(NIPAM)-g-CNCs at the oil-water interface. PMID:22204973

Zoppe, Justin O; Venditti, Richard A; Rojas, Orlando J

2011-12-13

436

Adsorption of mixed cationic-nonionic surfactant and its effect on bentonite structure.  

PubMed

The adsorption of cationic-nonionic mixed surfactant onto bentonite and its effect on bentonite structure were investigated. The objective was to improve the understanding of surfactant behavior on clay mineral for its possible use in remediation technologies of soil and groundwater contaminated by toxic organic compounds. The cationic surfactant used was hexadecylpyridinium bromide (HDPB), and the nonionic surfactant was Triton X-100 (TX100). Adsorption of TX100 was enhanced significantly by the addition of HDPB, but this enhancement decreased with an increase in the fraction of the cationic surfactant. Part of HDPB was replaced by TX100 which decreased the adsorption of HDPB. However, the total adsorbed amount of the mixed surfactant was still increased substantially, indicating the synergistic effect between the cationic and nonionic surfactants. The surfactant-modified bentonite was characterized by Brunauer-Emmett-Teller specific surface area measurement, Fourier transform infrared spectroscopy, and thermogravimetric-derivative thermogravimetric/differential thermal analyses. Surfactant intercalation was found to decrease the bentonite specific surface area, pore volume, and surface roughness and irregularities, as calculated by nitrogen adsorption-desorption isotherms. The co-adsorption of the cationic and nonionic surfactants increased the ordering conformation of the adsorbed surfactants on bentonite, but decreased the thermal stability of the organobentonite system. PMID:23513697

Zhang, Yaxin; Zhao, Yan; Zhu, Yong; Wu, Huayong; Wang, Hongtao; Lu, Wenjing

2012-01-01

437

FORMULATION AND PHARMACEUTICAL EVALUATION OF THREE W\\/O EMULSIONS WITH MYTILUS GALLOPROVINCIALIS LMK. AND RAPANA VENOSA LIPID EXTRACTS  

Microsoft Academic Search

The present paper presents new formulations of three lipid extracts of Mytilus galloprovincialis Lmk., Rapana venosa molluscs and those mixed (1:1, v\\/v) through their incorporation in W\\/O emulsions. These consisted of 4% lipid extracts (active ingredients), 60% liquid paraffin as the oil phase, 3% glycerin, 25.96% water as the water phase, 6% Span 60 as the surfactant and 0.04% nypagin

DIANA BADIU; FLORENTINA RONCEA

438

Ostwald ripening of concentrated alkane emulsions: a comparison of fiber-optics dynamic light scattering and conventional dynamic light scattering  

Microsoft Academic Search

The kinetics of aging processes in emulsions of undecane and dodecane stabilized by a surfactant is studied by dynamic light\\u000a scattering (DLS) and fiber-optics dynamic light scattering (FODLS). It appears that whereas DLS requires extremely diluted\\u000a clear samples (volume fraction typically 2?10?4) to follow the aging process, FODLS allows to monitor the aging in concentrated (volume fraction 0.2) and extremely

Y. De Smet; J. Malfait; C. De Vos; L. Deriemaeker; R. Finsy

439

Density fractionated hollow silica microspheres with high-yield by non-polymeric sol–gel\\/emulsion route  

Microsoft Academic Search

Hollow silica microspheres were synthesized by non-polymeric sol–gel\\/emulsion technique using tetra ethyl orthosilicate (TEOS) as a source of silica. A sol mixture of TEOS, water, ethanol and acid was emulsified in a solution of light paraffin oil and surfactant (Span-80). Calcined spheres were density fractionated between density ranges: 1.74gcm?3. The samples were characterized by optical and scanning electron microscopy with

R. K. Singh; A. Garg; R. Bandyopadhyaya; B. K. Mishra

2007-01-01

440

Asphalt-polyolefin emulsion breakdown  

Microsoft Academic Search

An analysis of factors controlling the stability of asphalt-polyolefin emulsions is given. From flocculation kinetics and changes in particle size distributions, it is concluded that the major cause of instability is due to Brownian coalescence followed by gravitational flocculation and creaming. A cyclical change in the particle size distribution, indicative of simultaneous flocculation and creaming, is observed only in the

S. A. M. Hesp; R. T. Woodhams

1991-01-01