Note: This page contains sample records for the topic emulsion behavior surfactant from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

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

SciTech Connect

This semi-annual technical progress report describes work performed at Clark Atlanta University under DOE Grant No. DE-FG26-97FT97278 during the period April 01, 1998 to October 01, 1998 which covers the second six months of the project. Presently work is in progress at the EOR Laboratory, Clark Atlanta University (CAU), to characterize phase and emulsion behavior for a novel, hybrid (ionic/non-ionic), alcohol ethoxycarboxylate surfactant (NEODOX 23-4 from Shell Chemical Company). During this reporting period, salinity scans were completed for 0, 5, 10, 20, 50, 100, 250, 500, 1000, 2000, 3000, 4000, 5000, and 6000 mM salt concentrations at 20, 25, and 30 °C to identify optimal salinity intervals in which all three phases coexist for this surfactant. Temperature scans were also performed at 20 mM salt concentration for various surfactant concentrations ranging from 0 to 60 weight percent at temperatures ranging from 5 to 50 °C to identify optimal surfactant concentration and temperature intervals in which all three phases coexist. This resulted in an "alpha" curve with an interval of temperature in which all three phases coexisted. Presently, temperature scans are being repeated at 100, 250, 500, 1000, and 5000 mM salt concentrations to see whether increase in salt concentration has any effect on the temperature interval. This will provide us better understanding and experimental control of the many variables involved in this research in the future. Following completion of the temperature scans, phase studies will be conducted at CAU, and coreflooding experiments at the facility of our industrial partner, Surtek, Golden, CO.

LEBONE MOETI; RAMANATHAN SAMPATH

1998-11-01

2

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

3

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

4

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

SciTech Connect

This semi-annual technical progress report describes work performed at Clark Atlanta University under DOE Grant No. DE-FG26-97FT97278 during the period October 01, 1997 to April 01, 1998 which covers the first six months of the project. During this reporting period, laboratory space to set up the surfactant characterization measurement system in the Research Science Center was made available. A Ph.D. student in Chemistry was identified and is supported as a Graduate Research Assistant in this project. Her contribution towards this project will form her Ph.D. thesis. The test matrix to perform salinity and temperature scans was established. Supply requests to obtain refined hydrocarbon, surfactant, and crude were processed and supplies obtained. A temperature bath with a control unit to perform temperature scans was obtained on loan from Federal Energy Technology Center, Morgantown, WV. The setting up of the temperature control unit, and associated chiller with water circulation lines is in progress. Tests were conducted on several hybrid surfactants to identify the best surfactants for future experimental work that yield almost equal volumes of top, middle, and bottom phases when mixed with oil and water. The student reviewed the current literature in the subject area, and modeling efforts that were established in previous studies to predict electrical conductivities and inversion phenomena. These activities resulted in one published conference paper, and one student poster paper during this reporting period.

Lebone T. Moeti; Ramanathan Sampath

1998-05-01

5

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

6

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

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

Liquid surfactant membrane emulsions. A new technique for enzyme immobilization.  

PubMed

Liquid membrane reactors are well known for metal extraction. This technology may also be applied to the immobilization of enzymes in enzyme emulsions. The use of liquid membrane reactors for enzymatic bioconversions has several advantages in comparison to solid membrane reactors and conventional immobilization techniques: there is no membrane fouling, enzyme emulsions can be used in cell-free fermentation broths, in complex mixtures the membrane can preselect the desired substrate for enzymatic reaction, and substances that might decrease the enzyme activity can be excluded. The separation effect is not based on differences in molecular weight but on the chemical behavior of the substances to be separated. Thus, it is not necessary to use cofactors with increased molecular weight for enzymatic reactions, since the coenzyme cannot permeate the liquid membrane. The three systems presented here indicate that enzyme systems can be easily immobilized in liquid surfactant membrane emulsions and there is a broad field of application for enzyme emulsions. PMID:3475010

Scheper, T; Makryaleas, K; Nowottny, C; Likidis, Z; Tsikas, D; Schügerl, K

1987-01-01

13

Surfactant-assisted spreading of an emulsion  

NASA Astrophysics Data System (ADS)

We studied experimentally the spreading dynamics of a drop of a surfactant-stabilized oil-in-water emulsion over the free surface of a layer of a solution of the same surfactant. The dynamics display three regimes. After the deposition of the emulsion drop, oil droplets are advected by a Marangoni flow, due to the difference in surfactant concentration between the emulsion and the liquid surface, and spread at the air/liquid interface. The oil droplets eventually stop, forming a dense ring, whose diameter is constant as long as oil droplets are transported by Marangoni flow. During this stage, oil droplets are moving rapidly on a surface with a low droplet concentration. Once the initial drop is empty, the ring collapses on itself, a phenomenon not yet reported experimentally to our knowledge. Spreading and retraction occur on a few hundred milliseconds while the ring stage lasts a few seconds. Using a laser sheet reflected by the surface of the liquid layer, we measured the shape of the surface and identified a jump of a few hundred microns in the layer thickness at the location of the ring. The existence of this jump points to hydrostatic pressure as the driving stress for retraction. We also show that this system shares many features with other jumps.

Li, Zhenzhen; Roche, Matthieu; Saint-Jalmes, Arnaud; Stone, Howard A.

2010-11-01

14

Antagonistic Effects between Magnetite Nanoparticles and a Hydrophobic Surfactant in Highly Concentrated Pickering Emulsions.  

PubMed

Herein we present a systematic study of the antagonistic interaction between magnetite nanoparticles (Fe3O4) and nonionic hydrophobic surfactant in Pickering highly concentrated emulsions. Interfacial tension measurements, phase behavior, and emulsion stability studies, combined with electron microscopy observations in polymerized systems and magnetometry, are used to support the discussion. First, stable W/O highly concentrated emulsions were obtained using partially hydrophobized magnetite nanoparticles. These emulsions experienced phase separation when surfactant is added at concentrations as low as 0.05 wt %. Such phase separation arises from the preferential affinity of the surfactant for the nanoparticle surfaces, which remarkably enhances their hydrophobicity, leading to a gradual desorption of nanoparticles from the interface. W/O emulsions were obtained at higher surfactant concentrations, but in this case, these emulsions were mainly stabilized by surfactant molecules. Therefore, stable emulsions could be prepared in two separate ranges of surfactant concentrations. After polymerization, low-density macroporous polymers were obtained, and the adsorption and aggregation of nanoparticles was analyzed by transmission electron microscopy. The progressive displacement of the nanoparticles was revealed: from the oil-water interface, in which aggregated nanoparticles were adsorbed, forming dense layers, to the continuous phase of the emulsions, where small nanoparticle aggregates were randomly dispersed. Interestingly, the results also show that the blocking temperature of the iron oxide superparamagnetic nanoparticles embedded in the macroporous polymers could be modulated by appropriate control of the concentrations of both surfactant and nanoparticles. PMID:24738961

Vílchez, Alejandro; Rodríguez-Abreu, Carlos; Menner, Angelika; Bismarck, Alexander; Esquena, Jordi

2014-05-13

15

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

16

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

17

Feasibility of Surfactant-Free Supported Emulsion Liquid Membrane Extraction  

NASA Technical Reports Server (NTRS)

Supported emulsion liquid membrane (SELM) is an effective means to conduct liquid-liquid extraction. SELM extraction is particularly attractive for separation tasks in the microgravity environment where density difference between the solvent and the internal phase of the emulsion is inconsequential and a stable dispersion can be maintained without surfactant. In this research, dispersed two-phase flow in SELM extraction is modeled using the Lagrangian method. The results show that SELM extraction process in the microgravity environment can be simulated on earth by matching the density of the solvent and the stripping phase. Feasibility of surfactant-free SELM (SFSELM) extraction is assessed by studying the coalescence behavior of the internal phase in the absence of the surfactant. Although the contacting area between the solvent and the internal phase in SFSELM extraction is significantly less than the area provided by regular emulsion due to drop coalescence, it is comparable to the area provided by a typical hollow-fiber membrane. Thus, the stripping process is highly unlikely to become the rate-limiting step in SFSELM extraction. SFSELM remains an effective way to achieve simultaneous extraction and stripping and is able to eliminate the equilibrium limitation in the typical solvent extraction processes. The SFSELM design is similar to the supported liquid membrane design in some aspects.

Hu, Shih-Yao B.; Li, Jin; Wiencek, John M.

2001-01-01

18

Biocompatible surfactants for water-in-fluorocarbon emulsions.  

PubMed

Drops of water-in-fluorocarbon emulsions have great potential for compartmentalizing both in vitro and in vivo biological systems; however, surfactants to stabilize such emulsions are scarce. Here we present a novel class of fluorosurfactants that we synthesize by coupling oligomeric perfluorinated polyethers (PFPE) with polyethyleneglycol (PEG). We demonstrate that these block copolymer surfactants stabilize water-in-fluorocarbon oil emulsions during all necessary steps of a drop-based experiment including drop formation, incubation, and reinjection into a second microfluidic device. Furthermore, we show that aqueous drops stabilized with these surfactants can be used for in vitro translation (IVT), as well as encapsulation and incubation of single cells. The compatability of this emulsion system with both biological systems and polydimethylsiloxane (PDMS) microfluidic devices makes these surfactants ideal for a broad range of high-throughput, drop-based applications. PMID:18813384

Holtze, C; Rowat, A C; Agresti, J J; Hutchison, J B; Angilè, F E; Schmitz, C H J; Köster, S; Duan, H; Humphry, K J; Scanga, R A; Johnson, J S; Pisignano, D; Weitz, D A

2008-10-01

19

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

2013-10-15

20

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

21

Stabilization of emulsions using polymeric surfactants based on inulin.  

PubMed

The use of polymeric surfactants for stabilization of emulsions is described. A brief account of general classification and description of polymeric surfactants is given. This is followed by a description of the adsorption and conformation of polymeric surfactants at interfaces. The theoretical approaches for studying polymer adsorption are briefly described. This is followed by a section on the experimental techniques that can be applied to study adsorption and conformation of polymers at the interface. Examples are given to illustrate the experimental techniques. A section is devoted to the interaction between droplets containing adsorbed polymer layers (steric stabilization). The last section gives results on oil-in-water (O/W) emulsions stabilised with a novel graft copolymeric surfactant based on inulin that has been modified by introducing alkyl groups. Two oils were used, namely Isopar M (isoparaffinic oil) and cyclomethicone. Emulsions prepared using the inulin-based surfactant have large droplets, but this could be significantly reduced by addition of a cosurfactant in the oil phase, namely Span 20. The stability of the emulsions was investigated in water, in 0.5, 1.0, 1.5 and 2 mol dm(-3) NaCl and in 0.5, 1.0, 1.5 and 2 mol dm(-3) MgSO(4). These emulsions were stable for more than 1 year up to 50 degrees C in NaCl concentrations up to 2 mol dm(-3) and 1 mol dm(-3) MgSO(4). This high stability in high electrolyte concentrations could be attributed to the nature of the hydrophilic (stabilizing) polyfructose chain. This was confirmed using cloud point measurements, which showed high hydration of the polyfructose chain in such high electrolyte concentrations. This ensured the long-term physical stability resulting from the strong steric repulsion between the polyfructose chains. PMID:15072943

Tadros, Th F; Vandamme, A; Levecke, B; Booten, K; Stevens, C V

2004-05-20

22

Surfactant-Free Switchable Emulsions Using CO2-Responsive Particles.  

PubMed

Surfactant-free emulsions are prepared using bi-wetting particles which occupy the oil-water interface to effectively reduce the oil-water interfacial area. The equilibrium position of the particle at the interface is determined by its wettability. CO2-reponsive chemical functional groups are grafted onto the surface of silica particles. Particles with only CO2-switchable functional groups are capable of stabilizing oil-in-water emulsions. Particles prepared with both CO2-responsive and hydrophobic chemical functional groups on its surface are capable of stabilizing water-in-oil emulsions. Emulsion stability is disturbed when the wettability of the stabilizing particle is altered by introducing CO2 gas to the biphasic mixture, leading to phase separation of emulsions prepared using the functionalized particles. The emulsion stability can be re-established by the removal of CO2 through air sparging. The presence of CO2 imposes positive surface charge to the responsive particles, increasing wettability and, consequently, the ability of the particles to destabilize emulsions. PMID:24679949

Liang, Chen; Liu, Qingxia; Xu, Zhenghe

2014-05-14

23

The jamming elasticity of emulsions stabilized by ionic surfactants.  

PubMed

Oil-in-water emulsions composed of colloidal-scale droplets are often stabilized using ionic surfactants that provide a repulsive interaction between neighboring droplet interfaces, thereby inhibiting coalescence. If the droplet volume fraction is raised rapidly by applying an osmotic pressure, the droplets remain disordered, undergo an ergodic-nonergodic transition, and jam. If the applied osmotic pressure approaches the Laplace pressure of the droplets, then the jammed droplets also deform. Because solid friction and entanglements cannot play a role, as they might with solid particulate or microgel dispersions, the shear mechanical response of monodisperse emulsions can provide critical insight into the interplay of entropic, electrostatic, and interfacial forces. Here, we introduce a model that can be used to predict the plateau storage modulus and yield stress of a uniform charge-stabilized emulsion accurately if the droplet radius, interfacial tension, surface potential, Debye screening length, and droplet volume fraction are known. PMID:24913542

Scheffold, Frank; Wilking, James N; Haberko, Jakub; Cardinaux, Frédéric; Mason, Thomas G

2014-06-25

24

Photoinduced demulsification of emulsions using a photoresponsive gemini surfactant.  

PubMed

This Article reports on the influence of light irradiation on the stability of emulsions prepared using a photoresponsive gemini surfactant (C7-azo-C7) having an azobenzene skeleton as a spacer. When mixtures of trans C7-azo-C7 aqueous solution and n-octane are homogenized, stable emulsions are obtained in a specific region of weight fraction and surfactant concentration. Fluorescence microscopy observations using a small amount of fluorescent probes show that the stable emulsions are oil-in-water (O/W)-type. UV irradiation of stable O/W emulsions promotes the cis isomerization of trans C7-azo-C7 and leads to the coalescence of the oil (octane) droplets in the emulsions, that is, demulsification. While the equilibrated interfacial tension (IFT) between aqueous trans C7-azo-C7 solution and octane is almost the same as that between aqueous cis C7-azo-C7 and octane, the occupied area per molecule for C7-azo-C7 at octane/water interface decreases with the cis photoisomerization of trans isomer. Dynamic IFT measurement shows that UV irradiation to the interface between aqueous trans C7-azo-C7 solution and octane brings about an increase in the interfacial tension, indicating that the Gibbs free energy at the interface increases. From these results, the cis isomerization of trans C7-azo-C7 molecules at the O/W interface due to UV irradiation leads to direct contact between the water and octane phases, because of the reduction of molecular area at the interface, and subsequently makes the emulsions demulsified. PMID:24354334

Takahashi, Yutaka; Fukuyasu, Kengo; Horiuchi, Tatsuya; Kondo, Yukishige; Stroeve, Pieter

2014-01-14

25

The Stability of Aerated Milk Protein Emulsions in the Presence of Small Molecule Surfactants  

Microsoft Academic Search

The effects of milk proteins and small molecular surfactants on oil droplet surface coverage and emul- sion stability were studied in model emulsions, and the results were related to the microstructure and physical properties of ice creams. Emulsions became increasingly more stable during partial coalescence at increased surface coverage as the protein concentra- tion was increased. Model emulsions of 20%

B. M. C. Pelan; K. M. Watts; I. J. Campbell; A. Lips

1997-01-01

26

Influence of molecular structure of hydrocarbon emulsion droplets on their solubilization in nonionic surfactant micelles  

Microsoft Academic Search

Light scattering was used to study the mass transport of hydrocarbon molecules from emulsion droplets to nonionic surfactant micelles. The hydrocarbons used as the dispersed phase of the emulsions were: 1-tetradecene, n-tetradecane, 1-hexadecene, n-hexadecane, 1-octadecene and n-octadecane. Oil-in-water emulsions were prepared which had the same initial droplet diameter (0.3 ?m), but different droplet concentrations (0 to 0.05 wt.%). The emulsion

Jochen Weiss; John N. Coupland; Dason Brathwaite; D. Julian McClements

1997-01-01

27

Tuning active emulsion dynamics via surfactants and topology.  

PubMed

We study water-in-oil emulsion droplets, running the Belousov-Zhabotinsky reaction, that form a new type of synthetic active matter unit. These droplets, stabilised by surfactants dispersed in the oil medium, are capable of internal chemical oscillations and self-propulsion. Here we present studies of networks of such self-propelled chemical oscillators and show that the resulting dynamics depend strongly on the topology of the active matter units and their connections. The chemical oscillations can couple via the exchange of promoter and inhibitor type of reaction intermediates across the droplets under precise conditions of surfactant bilayer formation between the droplets. The self-emerging synchronization dynamics are then characterized by the topology of the oscillator networks. Further, we show that the chemical oscillations inside the droplets cause oscillatory speed variations in the motion of individual droplets, extending our previous studies on such swimmers. Finally, we demonstrate that qualitatively new types of self-propelled motion can occur when simple droplet networks, for example two droplets connected by a bilayer, are set into motion. Altogether, these results lead to exciting possibilities in future studies of autonomous active matter. PMID:23989755

Thutupalli, Shashi; Herminghaus, Stephan

2013-08-01

28

Surfactant effects on the microstructure and electrochemical properties of emulsion-derived lithium cobalt oxide powders  

Microsoft Academic Search

The surfactant effects on the microstructure and electrochemical properties of lithium cobalt oxide (LiCoO2) powders prepared from emulsion-derived precursors have been investigated in this study. The single-phase LiCoO2 powders with R3?m structure are successfully prepared. The crystallinity and particle size of the obtained powders are varied with the amount of the surfactant used for preparing the emulsion solution. Reducing the

Chung-Hsin Lu; Po-Ying Yeh

2001-01-01

29

Stability mechanism of W\\/O crude oil emulsion stabilized by polymer and surfactant  

Microsoft Academic Search

Polymer and surfactant can absorb at the oil–water interface and thus enhance the stability of emulsions. Turbiscan lab expert stabilizer, spinning drop interfacial tensionmeter and interfacial shear rheometer were employed to study the stability and stability mechanism of synthetic W\\/O crude oil emulsion stabilized by polymer and surfactant. Polymer concentration is the key factor to stabilize the synthetic W\\/O crude

Wanli Kang; Bin Xu; Yongjian Wang; Yuan Li; Xiuhua Shan; Faquan An; Jiaheng Liu

2011-01-01

30

Synergistic formation and stabilization of oil-in-water emulsions by a weakly interacting mixture of zwitterionic surfactant and silica nanoparticles.  

PubMed

Oil-in-water emulsions were formed and stabilized at low amphiphile concentrations by combining hydrophilic nanoparticles (NPs) (i.e., bare colloidal silica) with a weakly interacting zwitterionic surfactant, caprylamidopropyl betaine, to generate a high hydrophilic-lipophilic balance. The weak interaction of the NPs with surfactant was quantified with contact angle measurements. Emulsions were characterized by static light scattering to determine the droplet size distributions, optical photography to quantify phase separation due to creaming, and both optical and electron microscopy to determine emulsion microstructure. The NPs and surfactant acted synergistically to produce finer emulsions with a greater stability to coalescence relative to the behavior with either NPs or surfactant alone. As a consequence of the weak adsorption of the highly hydrophilic surfactant on the anionic NPs along with the high critical micelle concentration, an unusually large surfactant concentration was available to adsorb at the oil-water interface and lower the interfacial tension. The synergy for emulsion formation and stabilization for the two amphiphiles was even greater in the case of a high-salinity synthetic seawater aqueous phase. Here, higher NP adsorption at the oil-water interface was caused by electrostatic screening of interactions between (1) NPs and the anionic oil-water interface and (2) between the NPs. This greater adsorption as well as partial flocculation of the NPs provided a more efficient barrier to droplet coalescence. PMID:24409832

Worthen, Andrew J; Foster, Lynn M; Dong, Jiannan; Bollinger, Jonathan A; Peterman, Adam H; Pastora, Lucinda E; Bryant, Steven L; Truskett, Thomas M; Bielawski, Christopher W; Johnston, Keith P

2014-02-01

31

On the behaviour of nanoparticles in oil-in-water emulsions with different surfactants.  

PubMed

The distribution of narrowly dispersed gold nanoparticles in hexane-in-water emulsions was studied for different surfactants. Good surfactants such as SDS and Triton X-100 block the oil-water interfaces and confine particles in the droplet. Other surfactants (Tween 85 and Span 20) form synergistic mixtures with the nanoparticles at the interfaces that lower the surface tension more than any component. Supraparticles with fully defined particle distribution form in the droplets only for surfactants that block the interface. Other surfactants promote the formation of fcc agglomerates. Nanoparticles in emulsions behave markedly different from microparticles-their structure formation is governed by free energy minimization, while microparticles are dominated by kinetics. PMID:24652036

Lacava, Johann; Ouali, Ahmed-Amine; Raillard, Brice; Kraus, Tobias

2014-03-21

32

Rheological characterization of polysaccharide-surfactant matrices for cosmetic O/W emulsions.  

PubMed

Rheometrical techniques can be profitably used for polysaccharide matrices in order to evaluate their suitability for the preparation of stable cosmetic O/W emulsions. In particular, the rheological properties of aqueous scleroglucan systems were investigated under continuous and oscillatory shear conditions in a polymer concentration range (0.2-1.2% w/w) embracing the sol/gel transition. The effects due to the addition of two different surfactants (up to 10% w/w) were examined at constant polymer concentration (0.4% w/w). The selected additives are a nonionic polymeric siliconic surfactant (dimethicone copolyol) and a cationic surfactant (tetradecyltrimethylammonium bromide), respectively. Polysaccharide-surfactant interactions leading to complex formation were detected also through rheology. The combined action of both nonionic and cationic surfactants in the polymer solution was examined at two different surfactant concentration levels (5 and 10% w/w), demonstrating the beneficial effects produced on the mechanical properties of the polymer matrix by the coexistence of both surfactants. Such beneficial effects are confirmed by the stability and rheology shown by the emulsions prepared. In this way, the results point out the good agreement between the rheology of the continuous phase and the final characteristics of the emulsion obtained. PMID:15963520

Bais, D; Trevisan, A; Lapasin, R; Partal, P; Gallegos, C

2005-10-15

33

Kinetics of Semibatch Emulsion Polymerization of Butyl Acrylate Stabilized by a Reactive Surfactant  

Microsoft Academic Search

The monomer feed rate (Ra) is the predominant parameter for controlling the rate of polymerization (Rp) in the semibatch emulsion polymerization of butyl acrylate (BA) stabilized by a reactive surfactant, sodium dodecyl allyl sulfosuccinate (SDAS). An induction period or even a complete inhibition of the polymer reaction observed for the experiments with relatively high SDAS concentration ([SDAS]) or low initiator

C.-S. CHERN; Y.-C. CHEN

1998-01-01

34

Feasibility of Surfactant-Free Supported Emulsion Liquid Membrane Extraction.  

National Technical Information Service (NTIS)

Supported emulsion liquid membrane (SELM) is an effective means to conduct liquid-liquid extraction. SELM extraction is particularly attractive for separation tasks in the microgravity environment where density difference between the solvent and the inter...

S. Y. B. Hu J. Li J. M. Wiencek

2001-01-01

35

Effect of the hydrophilic surfactants on the preparation and encapsulation efficiency in course and fine W\\/O\\/W type emulsions  

Microsoft Academic Search

Although the surfactant plays an important role in the preparation of a water-in-oil-in-water (W\\/O\\/W) emulsion, its concentration has been determined empirically. We investigated the location of a hydrophilic surfactant in a coarse W\\/O\\/W emulsion and a membrane-filtered fine emulsion. At first, appropriate concentrations of some hydrophilic surfactants to prepare a W\\/O\\/W emulsion were investigated from the viewpoints of the median

Motohiro Shima; Yohei Kobayashi; Yukitaka Kimura; Shuji Adachi; Ryuichi Matsuno

2004-01-01

36

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

37

Macroporous Polymers with Hierarchical Pore Structure from Emulsion Templates Stabilised by Both Particles and Surfactants.  

PubMed

Inspired by natural porous materials, such as wood, bamboo and spongy bone consisting of individual structural units that are hierarchically arranged to optimise mechanical properties such as strength and toughness, synthetic macroporous polymers with enhanced physical properties were created by emulsion templating. Hierarchical poly(merised) high internal phase emulsions (HIPE) were created from HIPEs stabilised simultaneously by particles and a surfactant. In these HIPEs, surfactant stabilised and particle stabilised water droplets coexist, which upon polymerisation of the minority oil phase gives rise to macroporous polymers with a hierarchical pore structure. An improvement of the mechanical properties of our hierarchically structured macroporous polymers at equal porosity was observed, due to a more efficient packing of pores in a configuration that improves mechanical strength despite the presence of interconnecting pore throats. Moreover, the permeability of the hierarchically structured polyHIPEs are exceeding those measured for conventional polyHIPEs made from surfactant only stabilised HIPEs. PMID:21800395

Wong, Ling L Ching; Ikem, Vivian O; Menner, Angelika; Bismarck, Alexander

2011-07-28

38

Janus particles on colloidosomes (Pickering emulsions) and the role of added surfactant  

NASA Astrophysics Data System (ADS)

We describe systematically the synergy between particle and surfactant in stabilizing colloidosomes. Special attention is given to what determines the inversion between O/W and W/O emulsions, the so-called `catastrophic phase inversion'. At the onset of the catastrophic phase inversion, we find an exceptional double-emulsion structure. Extending this idea, we find that when the dispersed phase is frozen by lowering the temperature below its solid-liquid phase transition, particles can be locked at the interface and further chemically modified into Janus colloidal particles. This affords an easy way to produce Janus colloidal particles with versatile chemical makeup in large quantity.

Jiang, Shan; Hong, Liang; Granick, Steve

2007-03-01

39

Isotonic swelling behavior of W\\/O\\/W emulsion liquid membranes under agitation conditions  

Microsoft Academic Search

A new on-line technique is developed to continuously monitor the isotonic swelling behavior of water-in-oil-in-water (W\\/O\\/W) emulsion liquid membranes (ELMs) under agitation condition. The technique is based on electrical conductivity measurement. The effects of surfactant concentration, initial volume fraction of dispersed globules, and stirring speed on the swelling profiles of W\\/O\\/W ELMs are determined using the new on-line technique. With

Jun Yan; Rajinder Pal

2003-01-01

40

Phase behavior and nano-emulsion formation by the phase inversion temperature method.  

PubMed

Formation of oil-in-water nano-emulsions has been studied in the water/C12E4/isohexadecane system by the phase inversion temperature emulsification method. Emulsification started at the corresponding hydrophilic-lipophilic balance temperature, and then the samples were quickly cooled to 25 degrees C. The influence of phase behavior on nano-emulsion droplet size and stability has been studied. Droplet size was determined by dynamic light scattering, and nano-emulsion stability was assessed, measuring the variation of droplet size as a function of time. The results obtained showed that the smallest droplet sizes were produced in samples where the emulsification started in a bicontinuous microemulsion (D) phase region or in a two-phase region consisting of a microemulsion (D) and a liquid crystalline phase (L(alpha)). Although the breakdown process of nano-emulsions could be attributed to the oil transference from the smaller to the bigger droplets, the increase in instability found with the increase in surfactant concentration may be related to the higher surfactant excess, favoring the oil micellar transport between the emulsion droplets. PMID:15274560

Izquierdo, Paqui; Esquena, Jordi; Tadros, Tharward F; Dederen, Joseph C; Feng, Jin; Garcia-Celma, Maria J; Azemar, Núria; Solans, Conxita

2004-08-01

41

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

42

Synthesis and surface properties of PDMS–acrylate emulsion with gemini surfactant as co-emulsifier  

Microsoft Academic Search

Composite latex particles of acrylate and polydimethylsiloxane (PDMS) with high PDMS content was prepared by emulsion copolymerization\\u000a and characterized by particle size analyzer, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR).\\u000a With gemini surfactant as the co-emulsifier in the system, the PDMS content in the system reached 50%, which was far higher\\u000a than the other reported values. Through the

Xiaobo Deng; Rong Luo; Hualin Chen; Bailing Liu; Yujun Feng; Yuhai Sun

2007-01-01

43

Ultrasound-assisted production of W\\/O emulsions in liquid surfactant membrane processes  

Microsoft Academic Search

Liquid surfactant membrane (LSM) process is a novel and effective method for the recovery and separation of heavy metals and amino acids from aqueous solutions. Repeated production and destruction of W\\/O emulsions plays a crucial role in the LSM process. The aim of this work was to study the efficiency of emulsification with horn ultrasound (20kHz), in which the organic

Ruey-Shin Juang; Kung-Hsuan Lin

2004-01-01

44

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

2012-11-15

45

A one-step process for oil-in-water-in-oil double emulsion formation using a single surfactant.  

PubMed

A one-step double emulsification protocol using one surfactant was developed for oil-in-water-in-oil (O(1)/W/O(2)) double emulsions. Two n-alkane oils and three different surfactants were studied, with focus placed on a formulation containing mineral oil, glycerol monoleate (GMO) and deionized water. Phenomenologically, double emulsion formation and stability originate from the combined actions of phase inversion and interfacial charging of the oil/water interface during high shear homogenization. Based on the extent of double emulsion formation and stability, a critical emulsification zone dependent on the weight ratios of GMO to water was identified. Within this critical zone, enhanced O(1)/W/O(2) emulsion formation occurred at higher pH and lower salt concentrations, demonstrating the key role of interfacial charging on double emulsification. Overall, this novel approach provides a novel platform for the development of double emulsions with simple compositions and processing requirements. PMID:22925117

Pradhan, Mamata; Rousseau, Dérick

2012-11-15

46

Thermosensitive ionic microgels via surfactant-free emulsion copolymerization and in situ quaternization cross-linking.  

PubMed

A type of thermosensitive ionic microgel was successfully prepared via the simultaneous quaternized cross-linking reaction during the surfactant-free emulsion copolymerization of N-isopropylacrylamide (NIPAm) as the main monomer and 1-vinylimidazole or 4-vinylpyridine as the comonomer. 1,4-Dibromobutane and 1,6-dibromohexane were used as the halogenated compounds to quaternize the tertiary amine in the comonomer, leading to the formation of a cross-linking network and thermosensitive ionic microgels. The sizes, morphologies, and properties of the obtained ionic microgels were systematically investigated by using transmission electron microscopy (TEM), dynamic and static light scattering (DLS and SLS), electrophoretic light scattering (ELS), thermogravimetric analyses (TGA), and UV-visible spectroscopy. The obtained ionic microgels were spherical in shape with narrow size distribution. These ionic microgels exhibited thermosensitive behavior and a unique feature of poly(ionic liquid) in aqueous solutions, of which the counteranions of the microgels could be changed by anion exchange reaction with BF4K or lithium trifluoromethyl sulfonate (PFM-Li). After the anion exchange reaction, the ionic microgels were stable in aqueous solution and could be well dispersed in the solvents with different polarities, depending on the type of counteranion. The sizes and thermosensitive behavior of the ionic microgels could be well tuned by controlling the quaternization extent, the type of comonomer, halogenated compounds, and counteranions. The ionic microgels showed superior swelling properties in aqueous solution. Furthermore, these ionic microgels also showed capabilities to encapsulate and release the anionic dyes, like methyl orange, in aqueous solutions. PMID:24588095

Zhou, Xianjing; Zhou, Yuanyuan; Nie, Jingjing; Ji, Zhichao; Xu, Junting; Zhang, Xinghong; Du, Binyang

2014-03-26

47

Release of markers from the inner water phase of W \\/ O \\/ W emulsions stabilized by silicone based polymeric surfactants  

Microsoft Academic Search

Silicone based surfactants were used as stabilizers for W\\/O\\/W double emulsions with unusual mechanical stability. W\\/O\\/ W multiple emulsions containing several markers were prepared. The entrapped markers were: (1) halide salts, (2) a typical drug, ephedrine hydrochloride, and (3) KNO3 (water soluble fertilizer).Good solute trapping (95% yield of preparation) with slow release rates through the liquid oil membrane (60% release

Y. Sela; S. Magdassi; N. Garti

1995-01-01

48

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

49

Droplet size distributions in turbulent emulsions: breakup criteria and surfactant effects from direct numerical simulations.  

PubMed

Lattice Boltzmann simulations of water-in-oil (W/O) type emulsions of moderate viscosity ratio (?1/3) and with oil soluble amphiphilic surfactant were used to study the droplet size distribution in forced, steady, homogeneous turbulence, at a water volume fraction of 20%. The viscous stresses internal to the droplets were comparable to the interfacial stress (interfacial tension), and the droplet size distribution (DSD) equilibrated near the Kolmogorov scale with droplet populations in both the viscous and inertial subranges. These results were consistent with known breakup criteria for W/O and oil-in-water emulsions, showing that the maximum stable droplet diameter is proportional to the Kolmogorov scale when viscous stresses are important (in contrast to the inviscid Hinze-limit where energy loss by viscous deformation in the droplet is negligible). The droplet size distribution in the inertial subrange scaled with the known power law ~d(-10/3), as a consequence of breakup by turbulent stress fluctuations external to the droplets. When the turbulent kinetic energy was sufficiently large (with interfacial Péclet numbers above unity), we found that turbulence driven redistribution of surfactant on the interface inhibited the Marangoni effect that is otherwise induced by film draining during coalescence in more quiescent flow. The coalescence rates were therefore not sensitive to varying surfactant activity in the range we considered, and for the given turbulent kinetic energies. Furthermore, internal viscous stresses strongly influenced the breakup rates. These two effects resulted in a DSD that was insensitive to varying surfactant activity. PMID:24206328

Skartlien, R; Sollum, E; Schumann, H

2013-11-01

50

New approach for the control of size and surface characteristics of mesoporous silica particles by using mixed surfactants in W\\/O emulsion  

Microsoft Academic Search

Mesoporous silica micro-spheres have been prepared using an emulsion-gel method in W\\/O emulsion consisting of aqueous solution of SDS or Tween 20 and n-octanol of hydroxypropyl cellulose (HPC) and Span 80. The morphology of water droplets in W\\/O emulsion was controlled by the concentration of the water-soluble surfactants of SDS and Tween 20 and the oil-soluble surfactant of Span 80.

Yong-Geun Lee; Chul Oh; Sang-Ki Yoo; Sang-Man Koo; Seong-Geun Oh

2005-01-01

51

Hydrodynamic behavior of water: tri-n-butylphosphate emulsions during ultrafiltration  

SciTech Connect

The behavior of tri-n-butylphosphate (TBP)-water emulsion is studied during ultrafiltration through two membranes with pore diameters of 1.2 and 1.5 nm, respectively. The emulsion is stabilized with two surfactants: Montane 80 and Montanox 80, which are lipophilic and hydrophilic, respectively. Their percentages never exceeded 10% of the organic part. The organic/water ratio decreases more (i.e., from 1/3 to 1/7) the higher the permeate when the pressure above the membrane is constant. The more the organic/water (O/W) ratio increases, and the more the flow rate of the emulsion above the membrane decreases, a so-called polarization layer appears at the membrane surface and a reverse emulsion (water in TBP) is noticed along with a sudden change in the behavior of the ultrafiltration process. This is due to a change from a capillary transfer model to a diffusional model. The best operating conditions seem to be for a lower O/W ratio and a large retentate flow rate because the formation of the polarization layer is more difficult with a turbulent flow above the membrane surface.

Modolo, R.; Vittori, O.; Rumeau, M.

1984-01-01

52

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

53

Coalescence kinetics in surfactant stabilized emulsions: Evolution equations from direct numerical simulations  

SciTech Connect

Lattice Boltzmann simulations were used to study the coalescence kinetics in emulsions with amphiphilic surfactant, under neutrally buoyant conditions, and with a significant kinematic viscosity contrast between the phases (emulating water in oil emulsions). The 3D simulation domain was large enough (256 3rd power -- 10 7th power grid points) to obtain good statistics with droplet numbers ranging from a few thousand at early times to a few hundred near equilibrium. Increased surfactant contents slowed down the coalescence rate between droplets due to the Gibbs-Marangoni effect, and the coalescence was driven by a quasi-turbulent velocity field. The kinetic energy decayed at a relatively slow rate at early times, due to conversion of interfacial energy to kinetic energy in the flow during coalescence. Phenomenological, coupled differential equations for the mean droplet diameter D(t) and the number density nd(t) were obtained from the simulation data and from film draining theories. Local (in time) power law exponents for the growth of the mean diameter (and for the concomitant decrease of nd) were established in terms of the instantaneous values of the kinetic energy, coalescence probability, Gibbs elasticity, and interfacial area. The model studies indicated that true power laws for the growth of the droplet size and decrease of the number of droplets with time may not be justified, since the exponents derived using the phenomenological model were time dependent. In contrast to earlier simulation results for symmetric blends with surfactant, we found no evidence for stretched logarithmic scaling of the formD -- [ln (ct)]a for the morphology length, or exponential scalings associated with arrested growth, on the basis of the phenomenological model.

R. Skartlien; E. Sollum; A. Akselsen; P. Meakin; B. Grimes; J. Sjoblom

2012-12-01

54

Effect of surfactants on the interfacial tension and emulsion formation between water and carbon dioxide  

SciTech Connect

The lowering of the interfacial tension ({gamma}) between water and carbon dioxide by various classes of surfactants is reported and used to interpret complementary measurements of the capacity, stability, and average drop size of water-in-CO{sub 2} emulsions. {gamma} is lowered from {approximately}20 to {approximately}2 mN/m for the best poly(propylene oxide)-b-poly(ethylene oxide)-b-poly(propylene oxide) (PPO-b-PEO-b-PPO) and PeO-b-PPO-b-PEO Pluronic triblock copolymers, 1.4 mN/m for a poly(butylene oxide)-b-PEO copolymer, 0.8 mN/m for a perfluoropolyether (PEPE) ammonium carboxylate and 0.2 mN/m for PDMS{sub 24}-g-EO{sub 22}. The hydrophilic-CO{sub 2}-philic balance (HCB) of the triblock Pluronic and PDMS-g-PEO-PPO surfactants is characterized by the CO{sub 2}-to-water distribution coefficient and V-shaped plots of log {gamma} vs wt % EO. A minimum in {gamma} is observed for the optimum HCB. As the CO{sub 2}-philicity of the surfactant tail is increased, the molecular weight of the hydrophilic segment increases for an optimum HCB. The stronger interactions on both sides of the interface lead to a lower {gamma}. Consequently, more water was emulsified for the PDMS-based copolymers than either the PPO- or PBO-based copolymers.

Rocha, S.R.P. da; Harrison, K.L.; Johnston, K.P. [Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering] [Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering

1999-01-19

55

Micellization behavior of coarse grained surfactant models.  

PubMed

We use molecular dynamics simulations over microsecond time scales to study the micellization behavior of recently proposed continuum-space, coarse grained surfactant models. In particular, we focus on the MARTINI model by Marrink et al. [J. Phys. Chem. B 111, 7812 (2007)] and a model by Shinoda et al. [Soft Matter 4, 2454 (2008)]. We obtain the critical micelle concentration (cmc) and equilibrium aggregate size distributions at low surfactant loadings. We present evidence justifying modest extrapolations for determining the cmc at low temperatures, where significant sampling difficulties remain. The replica exchange method provides only modest improvements of sampling efficiency for these systems. We find that the two coarse grained models significantly underpredict experimental cmc near room temperature for zwitterionic surfactants, but are closer to measured values for nonionic ones. The aggregation numbers for both zwitterionic and nonionic surfactants are near those observed experimentally, but the temperature dependence of the cmc is incorrect in both cases, because of the use of an unstructured solvent. Possible refinements to the models to bring them into quantitative agreement with experiment are discussed. PMID:20331315

Sanders, Samantha A; Panagiotopoulos, Athanassios Z

2010-03-21

56

Micellization behavior of coarse grained surfactant models  

NASA Astrophysics Data System (ADS)

We use molecular dynamics simulations over microsecond time scales to study the micellization behavior of recently proposed continuum-space, coarse grained surfactant models. In particular, we focus on the MARTINI model by Marrink et al. [J. Phys. Chem. B 111, 7812 (2007)] and a model by Shinoda et al. [Soft Matter 4, 2454 (2008)]. We obtain the critical micelle concentration (cmc) and equilibrium aggregate size distributions at low surfactant loadings. We present evidence justifying modest extrapolations for determining the cmc at low temperatures, where significant sampling difficulties remain. The replica exchange method provides only modest improvements of sampling efficiency for these systems. We find that the two coarse grained models significantly underpredict experimental cmc near room temperature for zwitterionic surfactants, but are closer to measured values for nonionic ones. The aggregation numbers for both zwitterionic and nonionic surfactants are near those observed experimentally, but the temperature dependence of the cmc is incorrect in both cases, because of the use of an unstructured solvent. Possible refinements to the models to bring them into quantitative agreement with experiment are discussed.

Sanders, Samantha A.; Panagiotopoulos, Athanassios Z.

2010-03-01

57

Evaluation of HLB values of mixed non-ionic surfactants on the stability of oil-in-water emulsion system  

NASA Astrophysics Data System (ADS)

Emulsion oil-in-water was prepared with combination of emulsifiers (non-ionic surfactants) following the HLB (hydrophylic-lipophylic balance) method developed by Griffin. The emulsions were prepared at HLB 10, 11, 12, 13 and 13.6 consisting blend of non-ionic emulsifiers fatty acid ethoxylate with 20 moles bound ethylene oxide and Dehydol LS 1 with 1 mole bound ethylene oxide. A mixture of palm-based methyl ester consisting of C6-10 and C12-18 fatty acid composition was used as palm-based solvent. The physicochemical parameters of the emulsion were characterized by accelerate stability tested at 45°C for two months, measurement of particle size and viscosity test. The result of accelerate test showed that all the emulsion at different HLB were found to be stable in the 2 months observation which assumed to be stable in 1 year of storage. Meanwhile, the particle size measurement data showed that the optimum stable particle size of the emulsion was HLB 12±1. The viscosity test of the emulsion tends to support the data from the particle size and have maximum viscosity 189.89 cP at HLB 12. The obtained results indicate that the optimum stable emulsions can be formulated by a combination of emulsifiers with HLB 12±1 which is compatible with that of required HLB of the oil phase.

Nursakinah, I.; Ismail, A. R.; Rahimi, M. Y.; Idris, A. B.

2013-11-01

58

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

59

Synthesis of core–shell polystyrene nanoparticles by surfactant free emulsion polymerization using macro-RAFT agent  

Microsoft Academic Search

Novel approach for the synthesis of core–shell polystyrene nanoparticles by living hydrophilic polymer consisting of thiocarbonyl thio end group is reported. The surfactant free emulsion polymerization of styrene in the presence of macro-RAFT (reversible addition fragmentation chain transfer) agent is carried out to synthesize stable latex particles with smaller particle size. A macro-RAFT agent is prepared by homopolymerization of sodium

Niranjan Yeole; Dilip Hundiwale; Tushar Jana

2011-01-01

60

Two-way effects of surfactants on Pickering emulsions stabilized by the self-assembled microcrystals of ?-cyclodextrin and oil.  

PubMed

The influence of surfactants on the stability of cyclodextrin (CD) Pickering emulsions is not well understood. In this study, we report two-way effects of Tween 80 and soybean lecithin (PL) on the long term stability of Pickering emulsions stabilized by the self-assembled microcrystals of ?-CD and medium chain triglycerides (MCT). The CD emulsions in the absence and presence of Tween 80 or PL at different concentrations were prepared and characterized by the droplet size, viscosity, contact angle, interfacial tension and residual emulsion values. After adding Tween 80 and PL, similar effects on the size distribution and contact angle were observed. However, changes of viscosity and interfacial tension were significantly different and two-way effects on the stability were found: (i) synergistic enhancement by Tween 80; (ii) inhibition at low and enhancement at high concentrations by PL. The stability enhancement of Tween 80 was due to the interfacial tension decrease caused by the interaction of Tween 80 with CD at the o/w interface at lower concentrations, and significant viscosity increase caused by the Tween 80-CD assembly in the continuous phase. For PL at low concentrations, the replacement of ?-CD/MCT by ?-CD/PL particles at the o/w interface was observed, leading to inhibitory effects. High concentrations of PL resulted in an extremely low interfacial tension and stable emulsion. In conclusion, the extensive inclusion of surfactants by CD leads to their unique effects on the stability of CD emulsions, for which the changes of viscosity and interfacial tension caused by host-guest interactions play important roles. PMID:24901107

Li, Xue; Li, Haiyan; Xiao, Qun; Wang, Liuyi; Wang, Manli; Lu, Xiaolong; York, Peter; Shi, Senlin; Zhang, Jiwen

2014-07-21

61

Inverse-emulsion copolymerization of acrylamide and quaternary ammonium cationic monomers with block copolymeric surfactants: copolymer composition control using batch and semi-batch techniques  

Microsoft Academic Search

An experimental investigation of the inverse-emulsion copolymerization of acrylamide and quaternary ammonium cationic monomers (dimethylaminoethylacrylate, DMAEA and dimethylaminoethylmethacrylate, DMAEM) has been carried out using both a block copolymeric surfactant (HB246) whose hydrophilic moiety is polyethylene oxide and whose hydrophobic moiety is poly(12 hydroxy stearic acid) and sorbitan monoleate (SMO). Our results indicate that the choice of surfactant influences strongly the

José Hernández-Barajas; David J. Hunkeler

1997-01-01

62

Flows of Wet Foamsand Concentrated Emulsions  

NASA Technical Reports Server (NTRS)

The aim of this project was is to advance a microstructural understanding of foam and emulsion flows. The dynamics of individual surfactant-covered drops and well as the collective behavior of dilute and concentrated was explored using numerical simulations. The long-range goal of this work is the formulation of reliable microphysically-based statistical models of emulsion flows.

Nemer, Martin B.

2005-01-01

63

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] [Univ. of Bergen (Norway). Dept. of Chemistry

1996-08-10

64

Adsorptive behavior of surfactants on surface of Portland cement  

Microsoft Academic Search

On the surface of Portland cement, four surfactants have different adsorptive behaviors: ethoxylated fatty alcohol sulfate (AES) belongs to the lignosulfonate (LS)-type of adsorption; cetyl piridinium chloride (CPC) is kinetically controlled; condensates of naphthalene formaldehyde (NS) have a linear relationship of adsorbance vs. concentration; and ethoxylated alkyl phenol (TX-10) is not adsorbed. All adsorbed surfactants have their hydrocarbon chain toward

T Zhang; S Shang; F Yin; A Aishah; A Salmiah; T. L Ooi

2001-01-01

65

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

2012-11-01

66

Particle-stabilized surfactant-free medium internal phase emulsions as templates for porous nanocomposite materials: poly-Pickering-Foams.  

PubMed

We report on the successful use of particle-stabilized Medium Internal Phase Emulsion (MIPE) templates for the synthesis of porous polymer foams. In this case, carbon nanotubes (CNTs) were used to stabilize the minority phase as the continuous phase, through adsorption at the interface. The addition of the CNTs not only provides processing advantages (no need for traditional non-ionic molecular surfactants) but also enhances the mechanical and electrical properties of the final polyFoams. This approach allows the manufacture of both closed- and open-celled porous polymer foams in a one-pot process with porosities up to 66%. PMID:17309201

Menner, Angelika; Verdejo, Raquel; Shaffer, Milo; Bismarck, Alexander

2007-02-27

67

Preparation of CO?/N?-triggered reversibly coagulatable and redispersible polyacrylate latexes by emulsion polymerization using a polymeric surfactant.  

PubMed

We report here a novel approach for making reversibly coagulatable and redispersible polyacrylate latexes by emulsion (co)polymerization of methyl methacrylate (MMA) using a polymeric surfactant, poly(2-(dimethylamino)ethyl methacrylate)(10) -block-poly(methyl methacrylate)(14) . The surfactant was protonated with HCl prior to use. The resulted PMMA latexes were readily coagulated with trace amount of caustic soda. The coagulated latex particles, after washing with deionized water, could be redispersed into fresh water to form stable latexes again by CO(2) bubbling with ultrasonication. The recovered latexes could then be coagulated by N(2) bubbling with gentle heating. These coagulation and redispersion processes were repeatable by the CO(2) /N(2) bubbling. PMID:22488642

Zhang, Qi; Yu, Guoqiang; Wang, Wen-Jun; Li, Bo-Geng; Zhu, Shiping

2012-05-29

68

Mixed Micellization Behavior of 12-2-12 Gemini Surfactant with Some Alkyltrimetyl Ammonium Bromide Surfactants  

Microsoft Academic Search

Mixed micellization behavior of dimeric cationic surfactant ethanediyl-1,2-bis (dimethyldodecylammonium bromide) (12-2-12) with a series of monomeric cationic surfactants dodecyltrimethyl ammonium bromide (DTAB), tetradecyltrimethyl ammonium bromide (TTAB), and cetyltrimethyl ammonium bromide (CTAB) has been studied in aqueous and aqueous polyvinylpyrrolidone (PVP) solutions at 298.15, 308.15, and 318.15 K, respectively, using conductometric method. Various thermodynamic parameters like mixed micelle concentration (Cm), micelle mole

T. S. Banipal; A. K. Sood; Jaswinder Kaur; Kultar Singh

2011-01-01

69

Surfactant-free emulsions for waterborne, two-component polyurethane coatings  

Microsoft Academic Search

Catalytic chain transfer polymerisation based on cobalt II or III chelates is a free radical technique which allows the synthesis of functional oligomers with a terminal ?-substituted acrylate group. This paper will review the applications of such oligomers in the design of low molecular weight, graft and block copolymer emulsions and dispersions for waterborne, two-component polyurethane paints. Such emulsions and

J. Huybrechts; P. Bruylants; A. Vaes; A. De Marre

2000-01-01

70

Complex Phase Behavior in Aqueous Suspensions of Polymeric Surfactants  

NASA Astrophysics Data System (ADS)

The many similarities in morphological behavior exhibited by diblock copolymer melts and lyotropic surfactant suspensions suggest the existence of common physical principles underlying these phenomena. In an effort to identify such principles, we discuss equilibrium and kinetic aspects of the phase behavior observed via small-angle scattering in aqueous solutions of polyalkane-poly(ethylene oxide) block copolymers. The molecular weights of these copolymers are roughly twice that of common poly(ethylene oxide)-poly(propylene oxide) surfactants, leading to microphase separation and a rich mesophase polymorphism in the absence of solvent. Although structurally analogous to commonly studied surfactants of the CnEOm type, the phase behavior of these macromolecules is less sensitive to local composition fluctuations due to the highly entangled conformations associated with polymer chains. This facilitates theoretical analysis. We describe changes in morphological behavior as a function of increasing water content, focussing on qualitative and quantitative aspects of transitions between different ordered mesophases.

Hajduk, D. A.; Kossuth, M. B.; Hillmyer, M. A.; Bates, F. S.

1997-03-01

71

Phase inversion of emulsions containing a lipophilic surfactant induced by clay concentration.  

PubMed

Emulsions stabilized by clay particles and sorbitan monooleate (Span 80) were investigated, and an abnormal phase inversion was observed by increasing the concentration of clay particles in the aqueous phase. At a fixed concentration of Span 80 in the oil phase, the emulsions were oil-in-water (o/w) when the concentration of clay particles in the aqueous phase was low. Surprisingly, the emulsion inverted to water-in-oil (w/o) when the concentration of the hydrophilic clay particles was increased. On the basis of the results of rheological measurements and laser-induced fluorescent confocal microscopy observation, we suggest that this phase inversion is induced by the gel structures formed at high concentration of clay particles. The effects of clay concentration on the stability and the droplet size of these emulsions were also investigated. PMID:23445467

Zhang, Jingchun; Li, Lu; Wang, Jun; Xu, Jian; Sun, Dejun

2013-03-26

72

Aggregation Behavior of Surfactants with Different Molecular Structures in Aqueous Solution: DPD Simulation Study  

Microsoft Academic Search

The aggregation behavior of surfactants with different molecular structures in aqueous solution was investigated by Dissipative Particle Dynamics (DPD) coarse-grained model simulation. With a simple surfactant model, we investigated how variations in micelle size and structures of surfactants influence their aggregation behavior. The obvious effects on the aggregation properties of surfactants caused by the variation of the hydrophobic or hydrophilic

Yiming Li; Haixia Zhang; Mutai Bao; Qingguo Chen

2012-01-01

73

Use of a novel surfactant for improving the transportability\\/transportation of heavy\\/viscous crude oils  

Microsoft Academic Search

In this paper, we present the application of a newly designed surfactant molecule for enhancing the flow properties of heavy\\/viscous crude oils. A novel surfactant molecule was designed through an economic processing technique. The rheological behavior of heavy crude oil\\/aqueous solution of surfactant emulsions as well as heavy crude oil\\/surfactant emulsions has been investigated using a programmable viscometer. The effects

Yousef Al-Roomi; Reena George; Ahmed Elgibaly; Ali Elkamel

2004-01-01

74

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

2012-03-01

75

An NMR study of diffusion in surfactant-free emulsions and molten triglyceride mixtures  

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance (NMR) diffusion measurements have become extensively used analytical techniques, with applications in many fields. In this thesis these measurements have been employed to elucidate a mechanism of emulsion stabilization and to examine mobility of a mixture of substances at the molecular level. Emulsions (liquid-in-liquid mixtures) have widespread applications (pharmaceutical, food science, petrochemical, agrochemical), therefore it is important to understand what governs emulsion stability. It has been previously demonstrated that a degassing process stabilizes oil-in-water emulsions, however the mechanism behind this is debated. In this thesis the Cotts 13-interval NMR sequence was used to examine the effects of degassing, establishing which of two suggested mechanisms is responsible for producing stable emulsions. Triglyceride mixtures are commonly separated before characterisation, however, NMR measurements of diffusion in molten trilaurin-trimyristin mixes have been made. This sheds light on the behaviour of these mixtures and assisted in developing new methods for their characterisation. These applications illustrate the versatility of NMR diffusion measurements.

MacLean, Duncan A.

76

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

Microsoft Academic Search

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

Won Sun Ryoo

2005-01-01

77

Complex Phase Behavior in Aqueous Suspensions of Polymeric Surfactants  

Microsoft Academic Search

The many similarities in morphological behavior exhibited by diblock copolymer melts and lyotropic surfactant suspensions suggest the existence of common physical principles underlying these phenomena. In an effort to identify such principles, we discuss equilibrium and kinetic aspects of the phase behavior observed via small-angle scattering in aqueous solutions of polyalkane-poly(ethylene oxide) block copolymers. The molecular weights of these copolymers

D. A. Hajduk; M. B. Kossuth; M. A. Hillmyer; F. S. Bates

1997-01-01

78

Development of nonionic surfactant\\/phospholipid o\\/w emulsion as a paclitaxel delivery system  

Microsoft Academic Search

Paclitaxel is an anticancer agent with low aqueous solubility. More extensive clinical use of this drug is somewhat delayed due to lack of appropriate delivery vehicles. An attempt was made to adopt an o\\/w emulsion as the drug carrier which incorporated paclitaxel in the triacylglycerol stabilized by a mixed-emulsifier system. A suitable formulation was found in this study: 0.75 mg\\/ml

Pei Kan; Zhi-Beng Chen; Chau-Jen Lee; I-Ming Chu

1999-01-01

79

Switchable surfactants.  

PubMed

Many industrial applications that rely on emulsions would benefit from an efficient, rapid method of breaking these emulsions at a specific desired stage. We report that long-chain alkyl amidine compounds can be reversibly transformed into charged surfactants by exposure to an atmosphere of carbon dioxide, thereby stabilizing water/alkane emulsions or, for the purpose of microsuspension polymerization, styrene-in-water emulsions. Bubbling nitrogen, argon, or air through the amidinium bicarbonate solutions at 65 degrees C reverses the reaction, releasing carbon dioxide and breaking the emulsion. We also find that the neutral amidines function as switchable demulsifiers of an aqueous crude oil emulsion, enhancing their practical potential. PMID:16917059

Liu, Yingxin; Jessop, Philip G; Cunningham, Michael; Eckert, Charles A; Liotta, Charles L

2006-08-18

80

Properties of water-in-oil (W\\/O) nano-emulsions prepared by a low-energy emulsification method  

Microsoft Academic Search

Properties of water-in-oil (W\\/O) nano-emulsion formed by a low-energy emulsification method are described in this work. Nano-emulsions have been formed in water\\/mixed non-ionic surfactant\\/decane. Several mixtures of Span 20, Span 80, Tween 20 and Tween 80 were studied. Phase behavior studies and stability studies allowed to determine zones where nano-emulsions can be formed. Bluish and transparent W\\/O nano-emulsion with droplet

M. Porras; C. Solans; C. González; J. M. Gutiérrez

2008-01-01

81

Influence of lipophilic surfactant on the release kinetics of water-soluble molecules entrapped in a W\\/O\\/W multiple emulsion  

Microsoft Academic Search

The aim of this work was to study the release kinetics of a water-soluble drug from two different W\\/O\\/W multiple emulsions prepared with two lipophilic surfactants at different concentrations. The study of the kinetics under both iso-osmotic and hypo-osmotic conditions allowed us to distinguish between two possible release mechanisms: swelling-breakdown or facilitated diffusion. The results obtained indicate that water-soluble drug

N. Jager-Lezer; I. Terrisse; F. Bruneau; S. Tokgoz; L. Ferreira; D. Clausse; M. Seiller; J. L. Grossiord

1997-01-01

82

Phase behavior modeling in surfactant flooding. Summary of changes to the UTCHEM phase package.  

National Technical Information Service (NTIS)

The chemical simulation models, UTCHEM (from the University of Texas at Austin) has been used within the SPOR-Water improved oil recovery research program, in connection with experimental surfactant phase behavior measurements and surfactant floodings. Th...

A. Lohne

1991-01-01

83

Interaction forces in thin liquid films stabilized by hydrophobically modified inulin polymeric surfactant. 2. Emulsion films.  

PubMed

The interaction forces in emulsion films stabilized using hydrophobically modified inulin (INUTEC SP1) were investigated by measuring the disjoining pressure of a microscopic horizontal film between two macroscopic emulsion drops of isoparaffinic oil (Isopar M). A special measuring cell was used for this purpose whereby the disjoining pressure Pi was measured as a function of the equivalent film thickness hw. The latter was determined using an interferometric method. In this way Pi-hw curves were established at a constant INUTEC SP1 concentration of 2x10(-5) mol.dm-3 and at various NaCl concentrations. At a constant disjoining pressure of 36 Pa, a constant temperature of 22 degrees C, and a film radius of 100 microm, hw decreased with an increase in the NaCl concentration, Cel, and reached a constant value of 11 nm at Cel=5x10(-2) mol.dm-3. This reduction in film thickness is due to the compression of the electrical double layer, and at the above critical NaCl concentration any electrostatic repulsion is removed and only steric interaction remains. This critical electrolyte concentration represents the transition from electrostatic to steric interaction. At a NaCl concentration of 2x10(-4) mol.dm-3 the Pi-hw isotherms showed a gradual decrease in hw with an increase in capillary pressure, after which there was a jump in hw from approximately 30 to approximately 7.2 nm when Pi reached a high value of 2-5.5 kPa. This jump is due to the formation of a Newton black film (NBF), giving a layer thickness of the polyfructose loops of approximately 3.6 nm. The film thickness did not change further when the pressure reached 45 kPa, indicating the high stability of the film. Pi-hw isotherms were obtained at various NaCl concentrations, namely, 5x10(-2), 5x10(-1), 1.0, and 2.0 mol.dm-3. The initial thicknesses are within the range 9-11 nm, after which a transition zone starts, corresponding to a pressure of about 0.5 kPa. In this zone all films transform to an NBF with a jump, after which the thickness remains constant with a further increase in the disjoining pressure up to 45 kPa, with no film rupture. This indicates the very high stability of the NBF in the presence of high electrolyte concentrations. The high emulsion film stability (due to strong steric repulsions between the strongly hydrated loops of polyfructose) is correlated with the bulk emulsion stability. PMID:17279648

Exerowa, D; Gotchev, G; Kolarov, T; Khristov, Khr; Levecke, B; Tadros, Th

2007-02-13

84

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

85

Pickering Interfacial Catalysts for solvent-free biomass transformation: Physicochemical behavior of non-aqueous emulsions.  

PubMed

A key challenge in biomass conversion is how to achieve valuable molecules with optimal reactivity in the presence of immiscible reactants. This issue is usually tackled using either organic solvents or surfactants to promote emulsification, making industrial processes expensive and not environmentally friendly. As an alternative, Pickering emulsions using solid particles with tailored designed surface properties can promote phase contact within intrinsically biphasic systems. Here we show that amphiphilic silica nanoparticles bearing a proper combination of alkyl and strong acidic surface groups can generate stable Pickering emulsions of the glycerol/dodecanol system in the temperature range of 35-130°C. We also show that such particles can perform as Pickering Interfacial Catalysts for the acid-catalyzed etherification of glycerol with dodecanol at 150°C. Our findings shed light on some key parameters governing emulsion stability and catalytic activity of Pickering interfacial catalytic systems. This understanding is critical to pave the way toward technological solutions for biomass upgrading able to promote eco-efficient reactions between immiscible organic reagents with neither use of solvents nor surfactants. PMID:24360842

Fan, Zhaoyu; Tay, Astrid; Pera-Titus, Marc; Zhou, Wen-Juan; Benhabbari, Samy; Feng, Xiaoshuang; Malcouronne, Guillaume; Bonneviot, Laurent; De Campo, Floryan; Wang, Limin; Clacens, Jean-Marc

2014-08-01

86

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

National Technical Information Service (NTIS)

This semi-annual technical progress report describes work performed at Clark Atlanta University under DOE Grant No. DE-FG26-97FT97278 during the period October 01, 1997 to April 01, 1998 which covers the first six months of the project. During this report...

Lebone T. Moeti Ramanathan Sampath

1998-01-01

87

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

National Technical Information Service (NTIS)

This semi-annual technical progress report describes work performed at Clark Atlanta University under DOE Grant No. DE-FG26-97FT97278 during the period April 01, 1998 to October 01, 1998 which covers the second six months of the project. Presently work is...

L. Moeti R. Sampath

1998-01-01

88

Polymerization in emulsion microdroplet reactors  

NASA Astrophysics Data System (ADS)

The goal of this research project is to utilize emulsion droplets as chemical reactors for execution of complex polymerization chemistries to develop unique and functional particle materials. Emulsions are dispersions of immiscible fluids where one fluid usually exists in the form of drops. Not surprisingly, if a liquid-to-solid chemical reaction proceeds to completion within these drops, the resultant solid particles will possess the shape and relative size distribution of the drops. The two immiscible liquid phases required for emulsion polymerization provide unique and complex chemical and physical environments suitable for the engineering of novel materials. The development of novel non-ionic fluorosurfactants allows fluorocarbon oils to be used as the continuous phase in a water-free emulsion. Such emulsions enable the encapsulation of almost any hydrocarbon compound in droplets that may be used as separate compartments for water-sensitive syntheses. Here, we exemplify the promise of this approach by suspension polymerization of polyurethanes (PU), in which the liquid precursor is emulsified into droplets that are then converted 1:1 into polymer particles. The stability of the droplets against coalescence upon removal of the continuous phase by evaporation confirms the formation of solid PU particles. These results prove that the water-free environment of fluorocarbon based emulsions enables high conversion. We produce monodisperse, cross-linked, and fluorescently labeled PU-latexes with controllable mesh size through microfluidic emulsification in a simple one-step process. A novel method for the fabrication of monodisperse mesoporous silica particles is presented. It is based on the formation of well-defined equally sized emulsion droplets using a microfluidic approach. The droplets contain the silica precursor/surfactant solution and are suspended in hexadecane as the continuous oil phase. The solvent is then expelled from the droplets, leading to concentration and micellization of the surfactant. At the same time, the silica solidifies around the surfactant structures, forming equally sized mesoporous particles. The procedure can be tuned to produce well-separated particles or alternatively particles that are linked together. The latter allows us to create 2D or 3D structures with hierarchical porosity. Oil, water, and surfactant liquid mixtures exhibit very complex phase behavior. Depending on the conditions, such mixtures give rise to highly organized structures. A proper selection of the type and concentration of surfactants determines the structuring at the nanoscale level. In this work, we show that hierarchically bimodal nanoporous structures can be obtained by templating silica microparticles with a specially designed surfactant micelle/microemulsion mixture. Tuning the phase state by adjusting the surfactant composition and concentration allows for the controlled design of a system where microemulsion droplets coexist with smaller surfactant micellar structures. The microemulsion droplet and micellar dimensions determine the two types of pore sizes (single nanometers and tens of nanometers). We also demonstrate the fabrication of carbon and carbon/platinum replicas of the silica microspheres using a "lost-wax" approach. Such particles have great potential for the design of electrocatalysts for fuel cells, chromatography separations, and other applications. It was determined that slight variations in microemulsion mixture components (electrolyte concentration, wt% of surfactants, oil to sol ratio, etc.) produces strikingly different pore morphologies and particle surface areas. Control over the size and structure of the smaller micelle-templated pores was made possible by varying the length of the hydrocarbon block within the trimethyl ammonium bromide surfactant and characterized using X-ray diffraction. The effect of emulsion aging was studied by synthesizing particles at progressive time levels from a sample emulsion. It was discovered surface pore size increases after just a few hours, with

Carroll, Nick J.

89

On the transport of emulsions in porous media.  

PubMed

Emulsions appear in many subsurface applications including bioremediation, surfactant-enhanced remediation, and enhanced oil-recovery. Modeling emulsion transport in porous media is particularly challenging because the rheological and physical properties of emulsions are different from averages of the components. Current modeling approaches are based on filtration theories, which are not suited to adequately address the pore-scale permeability fluctuations and reduction of absolute permeability that are often encountered during emulsion transport. In this communication, we introduce a continuous time random walk based alternative approach that captures these unique features of emulsion transport. Calculations based on the proposed approach resulted in excellent match with experimental observations of emulsion breakthrough from the literature. Specifically, the new approach explains the slow late-time tailing behavior that could not be fitted using the standard approach. The theory presented in this paper also provides an important stepping stone toward a generalized self-consistent modeling of multiphase flow. PMID:17493630

Cortis, Andrea; Ghezzehei, Teamrat A

2007-09-01

90

Physicochemical stability of lipid injectable emulsions: correlating changes in large globule distributions with phase separation behavior.  

PubMed

Single particle optical sensing (SPOS) and visual inspection were used to characterize a series of lipid injectable emulsions (n=21) featuring three lipid types, two electrolyte conditions, and three pH levels (7.0, 4.75, and 2.5). Seven of the twenty-one sample conditions exhibited phase separation instability by visual inspection within 98 h of emulsion preparation. The phase instability was driven by electrolyte type and pH, and "cracking" phenomena were independent of lipid type despite the base lipids ranging almost two orders of magnitude in PFAT5 levels. Logistic regression analysis showed that the PFAT5 level determined 1h after admixture preparation was not correlated with phase separation behavior. However, PFAT5 measured at later times showed much improved correlations with emulsion instability. PFAT5 was highly correlated with neighboring cumulative distributions termed PFATX where X=2-10 microm. Although the admixtures studied were not clinically relevant, the data demonstrate some limitations of developing empirical correlations between single-point SPOS measurements and emulsion instability. An alternative limit test for emulsion stability based on the rate of change in the large globule counts is proposed to mitigate inherent deficiencies in the current USP Chapter 729 limit test based on single-point determination of PFAT5 values. PMID:17618071

Gonyon, Thomas; Patel, Pankaj; Owen, Heather; Dunham, Andrew J; Carter, Phillip W

2007-10-01

91

Phase behavior of medium and high internal phase water-in-oil emulsions stabilized solely by hydrophobized bacterial cellulose nanofibrils.  

PubMed

Water-in-oil emulsions stabilized solely by bacterial cellulose nanofibers (BCNs), which were hydrophobized by esterification with organic acids of various chain lengths (acetic acid, C2-; hexanoic acid, C6-; dodecanoic acid, C12-), were produced and characterized. When using freeze-dried C6-BCN and C12-BCN, only a maximum water volume fraction (?w) of 60% could be stabilized, while no emulsion was obtained for C2-BCN. However, the maximum ?w increased to 71%, 81%, and 77% for C2-BCN, C6-BCN, and C12-BCN, respectively, 150 h after the initial emulsification, thereby creating high internal phase water-in-toluene emulsions. The observed time-dependent behavior of these emulsions is consistent with the disentanglement and dispersion of freeze-dried modified BCN bundles into individual nanofibers with time. These emulsions exhibited catastrophic phase separation when ?w was increased, as opposed to catastrophic phase inversion observed for other Pickering emulsions. PMID:24400918

Lee, Koon-Yang; Blaker, Jonny J; Murakami, Ryo; Heng, Jerry Y Y; Bismarck, Alexander

2014-01-21

92

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

93

The adsorption behavior of cationic surfactant onto human hair fibers  

Microsoft Academic Search

Quaternary ammonium surfactants are important ingredients that are frequently formulated into hair care products to modify the properties of hair surface. The adsorption kinetics, isotherms and association structures of cationic surfactants on hair surface, however, are not fully understood due to the heterogeneous nature of human hair fibers. In this work, a quaternary ammonium of surfactant, dimethylpabamidopropyl laurdimonium tosylate (DDABDT)

Guoxia Ran; Yang Zhang; Qijun Song; Yue Wang; Dexian Cao

2009-01-01

94

Effect of inorganic electrolytes on dissolution behavior of mixed anionic-amphoteric surfactant systems  

Microsoft Academic Search

The effects of some inorganic electrolytes on the dissolution behavior of anionic-amphoteric mixed surfactant systems have\\u000a been studied in terms of dissolution temperature of a hydrated solid surfactant; these systems are sodium dodecyl sulfate\\u000a (SDS) - N?,N?-dimethyl-N?-lauroyl lysine (DMLL), including different inorganic electrolytes (NaCl, NaSCN, or CaCl2). The dissolution temperatures of mixed surfactant systems are lower than those of pure

Kelzó Ogino; Kazúo Kato; Masahlko Abe

1988-01-01

95

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

96

Defect configurations and dynamical behavior in a Gay-Berne nematic emulsion  

NASA Astrophysics Data System (ADS)

To model a nematic emulsion consisting of a surfactant-coated water droplet dispersed in a nematic host, we performed a molecular dynamics simulation of a droplet immersed in a system of 2048 Gay-Berne ellipsoids in a nematic phase. Strong radial anchoring at the surface of the droplet induced a Saturn ring defect configuration, consistent with theoretical predictions for very small droplets. A surface ring configuration was observed for lower radial anchoring strengths, and a pair of point defects was found near the poles of the droplet for tangential anchoring. We also simulated the falling ball experiment and measured the drag force anisotropy, in the presence of strong radial anchoring as well as zero anchoring strength.

Billeter, Jeffrey L.; Pelcovits, Robert A.

2000-07-01

97

Osmotic swelling behavior of globules of W\\/O\\/W emulsion liquid membranes  

Microsoft Academic Search

The osmotic swelling behavior of water-in-oil-in-water (W\\/O\\/W) type emulsion liquid membranes (ELMs) was investigated. Using an optical microscope equipped with a camera, the changes in the size of the W\\/O\\/W globules were monitored over a long period of time (up to about 4h). The osmotic pressure gradient between the internal and external aqueous phases was induced by creating a concentration

Jun Yan; Rajinder Pal

2001-01-01

98

Anomalies in solution behavior of an alkyl aminopolycarboxylic chelating surfactant.  

PubMed

The solution behavior of a DTPA (diethylenetriamine pentaacetic acid)-based chelating surfactant, 4-C12-DTPA, has been studied by tensiometry and NMR diffusometry. In the absence of metal ions, the eight donor atoms in the headgroup are titrating, and the charge of the headgroup can thus be tuned by altering the pH. 4-C12-DTPA changes from cationic at very low pH, over a number of zwitterionic species as the pH is increased, and eventually becomes anionic at high pH. Around the isoelectric point, the chelating surfactant precipitated. The solution properties, studied above the solubility gap, were found strongly pH dependent. When increasing the amount of negative charges in the headgroup, by increasing the pH, the adsorption efficiency was reduced and the cmc was increased. An optimum in surface tension reduction was found at pH 5, due to a proper balance between protonated and dissociated groups. Anomalies between surface tension measurements and NMR diffusometry in determination of cmc revealed a more complex relation between surface tension, surface coverage, and cmc than usually considered, which is not in line with the common interpretation of the Gibbs adsorption equation. At some of the investigated pH levels, measurements of bulk pH could confirm the location of cmc, due to the increased protonation of micelles compared to monomers in solution. The adsorption of monomers to the air-water interface showed unusually slow time dependence, evident from decreasing surface tension for several hours. This is explained by rearrangements of the large head groups to reduce the headgroup area and increase the packing parameter. PMID:24111734

Svanedal, Ida; Persson, Gerd; Norgren, Magnus; Edlund, Håkan

2013-11-12

99

A rheological investigation of the self-assembly and adsorption behavior of a surfactant salt  

Microsoft Academic Search

The properties of a surfactant salt obtained by neutralizing oleic acid with an ethoxylated stearylamine were determined in blends of water and propylene glycol. The adsorption of this surfactant salt onto the surface of a commercial TiO2 dispersed in blends of water and propylene glycol was studied using a rheometer. At low propylene glycol content the dispersions exhibited Newtonian behavior,

Genhai G. Liang; Brian S. Hawkett; Roger I. Tanner

2005-01-01

100

Emulsion of aqueous-based nonspherical droplets in aqueous solutions by single-chain surfactants: templated assembly by nonamphiphilic lyotropic liquid crystals in water.  

PubMed

Single-chain surfactants usually emulsify and stabilize oily substances into droplets in an aqueous solution. Here, we report a coassembly system, in which single types of anionic or non-ionic surfactants emulsify a class of water-soluble nonamphiphilic organic salts with fused aromatic rings in aqueous solutions. The nonamphiphilic organic salts are in turn promoted to form droplets of water-based liquid crystals (chromonic liquid crystals) encapsulated by single-chain surfactants. The droplets, stabilized against coalescence by encapsulated in a layer (or layers) of single chain surfactants, are of both nonspherical tactoid (elongated ellipsoid with pointy ends) and spherical shapes. The tactoids have an average long axis of ?9 ?m and a short axis of ?3.5 ?m with the liquid crystal aligning parallel to the droplet surface. The spherical droplets are 5-10 ?m in diameter and have the liquid crystal aligning perpendicular to the droplet surface and a point defect in the center. Cationic and zwitterionic surfactants studied in this work did not promote the organic salt to form droplets. These results illustrate the complex interplay of self-association and thermodynamic incompatibility of molecules in water, which can cause new assembly behavior, including potential formation of vesicles or other assemblies, from surfactants that usually form only micelles. These unprecedented tactoidal shaped droplets also provide potential for the fabrication of new soft organic microcapsules. PMID:22726240

Varghese, Nisha; Shetye, Gauri S; Bandyopadhyay, Debjyoti; Gobalasingham, Nemal; Seo, JinAm; Wang, Jo-Han; Theiler, Barbara; Luk, Yan-Yeung

2012-07-24

101

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

102

Comparison of extraction efficiencies of penicillin G at different w\\/o ratios in the emulsion liquid membrane systems with dilute polymer solutions  

Microsoft Academic Search

A dilute polymer solution as the organic membrane phase was used to improve emulsion stability during extraction of penicillin G in emulsion liquid membrane (ELM) systems. Viscoelastic polymers were used to prepare the dilute polymer solution, which followed behavior of a non-Newtonian fluid. The effects of composition of polymer and surfactant in the membrane phase on extraction efficiency of penicillin

Sang Cheol Lee

2004-01-01

103

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...

104

Monte Carlo Simulations of the Phase Behavior of Surfactant Solutions  

Microsoft Academic Search

Phase diagrams are determined by Monte Carlo lattice simulations for idealized symmetric and asymmetric surfactant molecules mixed with single-site ``oil'' and ``water'' molecules. At high concentrations (above 20%) of surfactant, the simulations show the self assembly of liquid crystalline phases, including smectic, hexagonal, BCC sphere packings, and Ia3d gyroid cubic phases. The locations of the phases on the diagram for

R. G. Larson

1996-01-01

105

Lithographic performance and dissolution behavior of novolac resins for various developer surfactant systems  

NASA Astrophysics Data System (ADS)

The use of surfactants in today's society ranges over a wide variety of technologies, from soaps and detergents to house paints and electronic materials. In the semiconductor industry, surfactants are commonly used as coating additives in photoresists, as additives in wet chemical etchants, as additives in developer solutions, and in other areas where surface activity is desirable. In most applications, the mechanisms of surfactant chemistry are well established, yet there has been only a limited amount of published literature pertaining to characterizing the behavior of surfactants in developer systems for photoresists. This project explores the application of surfactants in an aqueous tetramethyl ammonium hydroxide (TMAH) based developer for two optical resists, one incorporating a 2,1,4- diazonaphthoquinone (DNQ) sensitizer, while the other incorporates a 2,1,5-DNQ sensitizer. In addition, each optical resist is based on different positive novolac resins with distinct structural properties. This feature aids in illustrating the improtance of matching the developer surfactant with the photoresist resin structure. Four distinct non-ionic surfactants with well published physical and chemical properties are examined. Properties of the surfactants explored include differences in structure, surfactant concentration, various degrees of hydrophilic versus lipophilic content (known as the HLB, or hydrophilic - lipophilic balance), and the differences in reported critical micelle concentration (CMC). Previous research investigated the performance characteristics of the 2,1,5-DNQ for these four surfactants. This investigation is an extension of the previous project by next considering a significantly different photoresist. A discussion of potential mechanisms of the solubilization and wetting effects is utilized to promote an understanding of surfactant effects in resist/developer systems. Also, because of the extensive characterization involved in screening surfactants, a recommended selection and screening scheme is proposed.

Flores, Gary E.; Loftus, James E.

1992-06-01

106

Phase behavior, morphology, and polymorphism of surfactant systems  

NASA Astrophysics Data System (ADS)

Surfactants are amphiphilic molecules. They spontaneously form various microstructures in water to accommodate the hydrophilic-hydrophobic interactions. Soaps are the oldest kind of man-made surfactants that are commonly used as washing and cleaning agents. In spite of the long history of soap research, many aspects of soaps in nonaqueous solvents remain unclear. Unlike the aqueous soap systems, which have been studied extensively, investigations of nonaqueous, polar soap systems are rather limited. Motivated by the applications of nonaqueous, polar solvents in soap products, we investigated sodium stearate (NaSt)/water/propylene glycol (PG) systems. The effects of gradual substitution of PG for H 2O on the phase behavior, morphology and crystalline structure of NaSt systems were studied by a combination of characterization techniques. The techniques include direct visual observation, differential scanning calorimetry, wide-angle and small angle x-ray scattering, light and cryo-electron microscopy, and solid-state nuclear magnetic resonance. Anhydrous NaSt forms layered crystalline structures at 25°C. With increasing temperature, a distorted hexagonal phase and a hexagonal liquid crystalline phase form. Compared with aqueous soap systems, the regions of liquid crystalline phases in the phase diagrams are reduced as PG replaces or gradually substitutes for H2O. Fibrous and plate-like NaSt crystallites were investigated in the NaSt/PG/H 2O system containing 1-5 wt% NaSt. Despite of the morphological difference, NaSt fibers and platelets share the same layered crystalline structure at the molecular level. NaSt fibers consist of stacked thin ribbons of NaSt bilayers. NaSt platelets exhibit large basal planes {001} surrounded by other faster-growing lateral planes. Two lamellar crystalline structures, alpha-NaSt and beta-NaSt, which formed in the NaSt/PG/H2O system with 10 wt% NaSt, were characterized on the atomic, molecular and microscopic levels. In a PG concentration range of 60-95 wt% in mixtures of H2O and PG, beta-NaSt transforms to alpha-NaSt upon aging. Compared with beta-NaSt, the hydrocarbon chains in alpha-NaSt consist of a higher percentage of trans conformation, which is characteristically more orderly packed and more rigid. alpha-NaSt exhibits a larger bilayer thickness, and dissolves at a lower temperature in the PG/H 2O mixture. The fibrous crystallites of alpha-NaSt are more bundled and oriented compared to those of beta-NaSt.

Liang, Jingmei

107

Liposomes in Double-Emulsion Globules  

PubMed Central

Tubular liposomes containing a hydrophilic model compound (fluorescein sodium salt, FSS) were entrapped inside the internal aqueous phase (W1) of water-in-oil-in-water (W1/O/W2) double-emulsion globules. Our hypothesis was that the oil membrane of double emulsions can function as a layer of protection to liposomes and their contents and thus better control their release. Liposomes were prepared in bulk, and their release was observed microscopically from individual double-emulsion globules. The liposomes containing FSS were released through external coalescence, and the behavior of this system was monitored visually by capillary video microscopy. Double-emulsion globules were stabilized with Tween 80 as the water-soluble surfactant, with Span 80 as the oil-soluble surfactant, while the oil phase (O) was n-hexadecane. The lipids in the tubular liposomes consist of l-?-phosphatidylcholine and Ceramide-VI. Variations of Tween 80 concentration in the external aqueous phase (W2) and Span 80 concentration in the O phase controlled the release of liposomes from the W1 phase to the W2 phase. The major finding of this work is that the sheer presence of liposomes in the W1 phase is by itself a stabilizing factor for double-emulsion globules.

Wang, Qing; Tan, Grace; Lawson, Louise B.; John, Vijay T.; Papadopoulos, Kyriakos D.

2010-01-01

108

Liposomes in double-emulsion globules.  

PubMed

Tubular liposomes containing a hydrophilic model compound (fluorescein sodium salt, FSS) were entrapped inside the internal aqueous phase (W(1)) of water-in-oil-in-water (W(1)/O/W(2)) double-emulsion globules. Our hypothesis was that the oil membrane of double emulsions can function as a layer of protection to liposomes and their contents and thus better control their release. Liposomes were prepared in bulk, and their release was observed microscopically from individual double-emulsion globules. The liposomes containing FSS were released through external coalescence, and the behavior of this system was monitored visually by capillary video microscopy. Double-emulsion globules were stabilized with Tween 80 as the water-soluble surfactant, with Span 80 as the oil-soluble surfactant, while the oil phase (O) was n-hexadecane. The lipids in the tubular liposomes consist of L-alpha-phosphatidylcholine and Ceramide-VI. Variations of Tween 80 concentration in the external aqueous phase (W(2)) and Span 80 concentration in the O phase controlled the release of liposomes from the W(1) phase to the W(2) phase. The major finding of this work is that the sheer presence of liposomes in the W(1) phase is by itself a stabilizing factor for double-emulsion globules. PMID:19958007

Wang, Qing; Tan, Grace; Lawson, Louise B; John, Vijay T; Papadopoulos, Kyriakos D

2010-03-01

109

Interpreting ion-specific effects on the reduction of an arenediazonium ion by t-butylhydroquinone (TBHQ) using the pseudophase kinetic model in emulsions prepared with a zwitterionic sulfobetaine surfactant.  

PubMed

Specific salt effects on the reduction of an amphiphilic arenediazonium ion, 16-ArN2(+), by TBHQ in opaque, stirred, and kinetically stable emulsions prepared with a zwitterionic sulfobetaine surfactant are consistent with the chameleon effect: selective anion binding/induced cation binding in the interfacial region of the emulsions. Added NaX salts with different anions decrease the observed first-order rate constant, k(obs), for the reduction in the order X(-) = ClO4(-) > Br(-) ? CCl3CO2(-) > Cl(-) > MeSO3(-). Added MCln salts of increasing cation valence at constant total Cl(-) concentration increase kobs in the order M(n+) = Cs(+) < Ca(2+) < Al(3+) in the same emulsions. These results, combined with recent results for nonionic and ionic emulsions, demonstrate that pseudophase kinetic models provide general, coherent explanations of chemical reactivity in homogeneous micelles, microemulsions, vesicles, and now biphasic emulsions and with all types of basic surfactant structures: nonionic, cationic, anionic, and now zwitterionic. PMID:23547802

Gao, Xiang; Bravo-Díaz, Carlos; Romsted, Laurence Stuart

2013-04-23

110

Effect of hydrotropes on the aqueous solution behavior of surfactants  

Microsoft Academic Search

Aqueous solutions of surfactants—cationic: tetradecyltrimethylammonium bromide (C14TABr); anionic: sodium dodecyl sulfate (SDS); and nonionic: polyoxyethylene t-octylphenol (trade name Triton X-102, also called OPE-8)— in the presence of three hydrotropes, viz., sodium xylene sulfonate, sodium p-toluene sulfonate, and sodium chlorobenzene sulfonate, were examined by measuring surface tension, viscosity, and cloud points\\u000a for the nonionic surfactant. The results show a marked decrease

Dharmesh Varade; Pratap Bahadur

2004-01-01

111

Polyelectrolyte/surfactant mixtures in the bulk and at water/oil interfaces.  

PubMed

Stabilization of emulsions by mixed polyelectrolyte/surfactant systems is a prominent example for the application in modern technologies. The formation of complexes between the polymers and the surfactants depends on the type of surfactant (ionic, non-ionic) and the mixing ratio. The surface activity (hydrophilic-lipophilic balance) of the resulting complexes is an important quantity for its efficiency in stabilizing emulsions. The interfacial adsorption properties observed at liquid/oil interfaces are more or less equivalent to those observed at the aqueous solution/air interface, however, the corresponding interfacial dilational and shear rheology parameters differ quite significantly. The interfacial properties are directly linked to bulk properties, which support the picture for the complex formation of polyelectrolyte/surfactant mixtures, which is the result of electrostatic and hydrophobic interactions. For long alkyl chain surfactants the interfacial behavior is strongly influenced by hydrophobic interactions while the complex formation with short chain surfactants is mainly governed by electrostatic interactions. PMID:24268973

Aidarova, S; Sharipova, A; Krägel, J; Miller, R

2014-03-01

112

Effects of surfactant on bubble hydrodynamic behavior under flotation-related conditions in wastewater.  

PubMed

Bubble behavior is fundamental to the performance of froth flotation operations used in wastewater treatment processes. To fully understand and characterize bubble behavior under flotation-related conditions in wastewater, the high-speed photographic method has been employed to examine the motion of single bubbles and size distribution of bubble swarms with intermediate sizes ranging from 1 to 4 mm in the presence of surfactants in a laboratory scale flotation column. Both distilled water and synthetic municipal wastewater have been used to make solutions as well as two types of common surfactants. The instantaneous bubble motion has been recorded by a high speed camera. Subsequently, bubble trajectory, dimensions, velocity and distribution have been determined from the recorded frames using the image analysis software. The experimental results show that the addition of surfactant into wastewater has similar effects on bubble hydrodynamic behavior as in pure water (e.g., improving trajectory stabilization, dampening bubble deformation, slowing down terminal velocity, reducing bubble size and increasing the specific surface area of bubble swarm) due to the Marangoni effect. However, it is interesting to note that surfactant effects on single bubble hydrodynamics in wastewater are slightly stronger than those in pure water while surfactant effects on size parameters of bubble swarms in wastewater are significantly stronger than those in pure water. This finding suggests that besides surfactant, inorganic salts present in synthetic wastewater have an important influence on bubble dispersion. PMID:22378003

Li, Yanpeng; Zhu, Tingting; Liu, Yanyan; Tian, Ye; Wang, Huanran

2012-01-01

113

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

114

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

2013-11-15

115

Experimental and computational investigations of surfactant physicochemical behavior during conditions emulating the opening of pulmonary airways  

NASA Astrophysics Data System (ADS)

We have investigated the mechanical influence of surfactant physicochemical properties on the progression of a semi-infinite air bubble in a fluid filled rigid capillary. This system mimics the continual interfacial expansion dynamics that occur during the opening of collapsed pulmonary airways. The goal of this study is to ascertain the surfactant physicochemical properties that are responsible for reducing airway reopening pressures that may damage lung epithelial cells. To accomplish this goal, we have developed experimental and computational models of this system. The experimental model is used to measure the ability of various surfactants to alter the reopening pressure. The non-physiologic surfactant, SDS, is capable of reducing the interfacial stresses that elevate the reopening pressure, the main component of pulmonary surfactant, L-alpha-dipalmitoyl phosphatidylcholine (DPPC), exhibits large stresses, and the clinically relevant surfactant, Infasurf, reduces the reopening pressure but maintains a surface shear or Marangoni stress. Infasurf's behavior suggests that optimal surfactant properties will reduce the reopening pressures that may damage airway epithelial cells while maintaining the Marangoni stress that enhances airway stability. Analysis of the experimental data is based on a modification of previous theoretical models which can not simulate non-equilibrium conditions near the bubble tip. Therefore, we have developed a theoretical model of surfactant effects that is capable of simulating these non-equilibrium dynamics. The coupled governing equations for fluid mechanics, molecular transport, and interfacial dynamics, are solved using a combined boundary element, dual reciprocity boundary element, and finite difference scheme. Scaling of the governing equations yields dimensionless parameters that identify the relative importance of surfactant physicochemical properties. Independent parameter variation studies are used to investigate how individual physicochemical properties influence the mechanics of the system. We found that the non-equilibrium adsorption of surfactant can significantly elevate the reopening pressure. In addition, a computational technique that simulates the experimental protocol indicates that Infasurf's sorption properties are at least ten times larger than DPPC. As a result of these studies, the surfactant physicochemical properties that influence lung inflation pressures and lung stability have been identified. Knowledge of these properties may be useful in the development and/or administration of novel pulmonary surfactant replacements.

Ghadiali, Samir Nuruddin

2000-10-01

116

The effect of surfactants on the electropolishing behavior of copper in orthophosphoric acid  

NASA Astrophysics Data System (ADS)

The electropolishing behavior of copper was studied in orthophosphoric acid with Triton X-100, sodium dodecyl sulphate and cetyl pyridinium chloride as additives for improving the finish obtained on copper surface. This was investigated by measuring and comparing anode potential-limiting current relationships in solutions of gradually increasing concentration of surfactants. The addition of surfactants to the electropolishing solution results in a lower limiting current. This confirms the mass transport of dissolved species from the anode surface to the bulk of solution as the rate-determining step in the presence of three surfactants in all concentrations investigated. Scanning electron microscope (SEM), atomic force microscope (AFM) and measured brightness values were used to investigate the copper surface after electropolishing and the results were compared to polishing done in absence of surfactants. According to SEM images and brightness values, addition of Triton X-100 was effective to enhance levelling and brightening more than sodium dodecyl sulphate and cetyl pyridinium chloride. AFM analysis showed that the roughness values (Ra) for an electropolished copper surface, in presence of surfactants, is significantly lower than in absence of surfactants. Different reaction conditions and the physical properties of solutions are studied to obtain dimensionless correlation among all these parameters.

Taha, A. A.; Ahmed, A. M.; Rahman, H. H. Abdel; Abouzeid, F. M.

2013-07-01

117

UHPH-processed O/W submicron emulsions stabilised with a lipid-based surfactant: physicochemical characteristics and behaviour on in vitro TC7-cell monolayers and ex vivo pig's ear skin.  

PubMed

Submicron O/W emulsions formulated with sesame oil plus a lipid-base surfactant, and with or without retinyl acetate (RAC) as a model hydrophobic biomolecule, were prepared by single-pass homogenisation at ? 200 MPa (UHPH) and an initial fluid temperature (Tin) of 24°C. These emulsions were characterised by a monomodal distribution (peak maximum at 260 nm) and a 2-year potential physical stability at ambient temperature. Submicron droplets were investigated in term of (i) physicochemical characteristics (size distribution curves; ?-potential value), and (ii) impact on TC7-cell monolayers (MTT-assay and cell LDH-leakage). Submicron droplets ± RAC did not affect or increased significantly (p=0.05) TC7-cell metabolic activity after 4-24h of exposure indicating absence of cellular impairment, except when high amounts of droplets were deposed on TC7-cells. Indeed, the lipid-based surfactant deposed alone on TC7-cells at high concentration, induced some significant (p=0.05) cell LDH-leakage, and therefore cell-membrane damage. Cellular uptake experiments revealed a significant (p=0.05) time-dependent internalisation of RAC from submicron droplets, and cellular transformation of RAC into retinol. The turnover of RAC into retinol and therefore RAC bioaccessibility appeared faster for RAC-micelles of similar size-range and prepared at atmospheric pressure with polysorbate 80, than for submicron O/W emulsions. Permeation experiments using pig's ear skin mounted on Franz-type diffusion cells, revealed RAC in dermis-epidermis, in significantly (p=0.05) higher amounts for submicron than coarse pre-emulsions. However, RAC amounts remained low for both emulsion-types and RAC was not detected in the receptor medium of Franz-type diffusion cells. PMID:24480065

Benzaria, Amal; Gràcia-Julià, Alvar; Picart-Palmade, Laëtitia; Hue, Pauline; Chevalier-Lucia, Dominique; Marti-Mestres, Gilberte; Hodor, Nadège; Dumay, Eliane

2014-04-01

118

Structure, properties, and surfactant adsorption behavior of fly ash carbon  

NASA Astrophysics Data System (ADS)

The objective of this research was to suggest methods by which certain problems associated with use of coal fly ash as a pozzolanic agent in concrete mixtures could be alleviated, guided by a better characterization of fly ash properties. A sample suite of eighty fly ashes was gathered from utilities across the world (mainly US-based) and included ashes from coals ranging in rank from bituminous to lignite. The widely used foam index test is used to characterize ashes with respect to their propensity to adsorb surfactants (called Air Entraining Admixtures or AEAs) used to impart freeze-thaw resistance to concrete. In ash-containing concrete mixtures, AEAs are adsorbed from the polar concrete-water solution onto non-polar unburned carbon surfaces in the ash. The AEA uptake by fly ashes only crudely correlates with the amount of carbon in the fly ash, because carbon surface area, accessibility and polarity all play a role in determining adsorption capacities. Fly ash carbon particle size distribution is also a key factor. Fine carbon particles in fly ash fractions of <106mum are responsible for about 90% of surfactant adsorption capacity. Surfactant adsorption on fly ash carbon is, in the foam index test, a dynamic process. The time of the test (typically <10 minutes) is not long enough to permit penetration of small porosity by the relatively large AEA molecules, and only the most readily available adsorption surface near the geometrical surface of the carbon particles is utilized. The nature of the foam index test was also examined, and it is recommended that a more standardized test procedure based upon pure reagents be adopted for examining the nature of fly ashes. Several possible reagents were identified. Room temperature fly ash ozonation is a powerful technique that allows increasing fly ash surface polarity in a relatively short time and thus is very effective for decreasing the AEA uptake capacity. Depending on the ozone input concentration, sample amount and contact time, surfactant uptake capacity decreases by a factor of two or more following reaction of only 0--1g O3/kg-ash, bringing many ashes into compliance with AEA uptake requirements.

Kulaots, Indrek

119

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

2013-05-21

120

Interfacial properties in solid-stabilized emulsions  

NASA Astrophysics Data System (ADS)

We prepared concentrated monodisperse oil-in-water emulsions stabilized by solid particles. The osmotic resistance, ?, of the emulsions was measured for different oil volume fractions above the random close packing (? ^*? 64{%}). The dimensionless osmotic resistance, ?/(?/R) (? being the interfacial tension and R being the undeformed drop radius), was always substantially higher than the corresponding values obtained for surfactant-stabilized emulsions. It can be concluded that droplet deformation in solid-stabilized emulsions is not controlled by the capillary pressure, ?/R, of the non-deformed droplets but rather by ?0/R, ?0 being a parameter characterizing the rigidity of the droplets surfaces. The data can be interpreted considering that the interfacial layers are elastic at small deformations and exhibit plasticity at intermediate deformations. ?0 corresponds to the surface yield stress, i.e. the transition between elastic and plastic regimes. We discuss the origin of the surface behavior considering the strong lateral interactions that exist between the adsorbed solid particles. We propose an independent measurement of ?0 based on the critical bulk stress that produces droplet fragmentation in dilute emulsions submitted to shear. Finally, the bulk shear elastic modulus was measured as a function of ? and confirms many of the features revealed by the osmotic resistance.

Arditty, S.; Schmitt, V.; Lequeux, F.; Leal-Calderon, F.

2005-04-01

121

Isotachophoresis with emulsions  

PubMed Central

An experimental study on isotachophoresis (ITP) in which an emulsion is used as leading electrolyte (LE) is reported. The study aims at giving an overview about the transport and flow phenomena occurring in that context. Generally, it is observed that the oil droplets initially dispersed in the LE are collected at the ITP transition zone and advected along with it. The detailed behavior at the transition zone depends on whether or not surfactants (polyvinylpyrrolidon, PVP) are added to the electrolytes. In a system without surfactants, coalescence is observed between the droplets collected at the ITP transition zone. After having achieved a certain size, the droplets merge with the channel walls, leaving an oil film behind. In systems with PVP, coalescence is largely suppressed and no merging of droplets with the channel walls is observed. Instead, at the ITP transition zone, a droplet agglomerate of increasing size is formed. In the initial stages of the ITP experiments, two counter rotating vortices are formed inside the terminating electrolyte. The vortex formation is qualitatively explained based on a hydrodynamic instability triggered by fluctuations of the number density of oil droplets.

Goet, G.; Baier, T.; Hardt, S.; Sen, A. K.

2013-01-01

122

Phase behavior and microstructures in a mixture of anionic Gemini and cationic surfactants.  

PubMed

We report in this work the phase behavior and microstructures in a mixture of an anionic Gemini surfactant, sodium dilauramino cystine (SDLC), and a conventional cationic surfactant, dodecyl trimethyl ammonium chloride (DTAC). Observation of the appearance shows that the phase behavior of the SDLC-DTAC mixed cationic surfactant system transforms from an isotropic homogeneous phase to an aqueous surfactant two-phase system (ASTP) and then to an anisotropic homogeneous phase with the continuous addition of DTAC. The corresponding aggregate microstructures are investigated by rheology, dynamic light scattering, transmission electron microscopy and polarization microscopy. It has been found that a wormlike micelle, in the isotropic homogeneous phase, occurs linear to the branch growth. The aggregate microstructures in the ASTP lower and upper phases are branched wormlike micelles and vesicles, respectively. The micelle transformed into a vesicle upon varying the phase volume percentage until a lamellar liquid crystal formed in the anisotropic homogeneous phase. The macroscopic phase behavior and microscopic aggregate structure are related to the understanding of the possible mechanisms for the above phenomena. PMID:24817411

Fan, Haiming; Li, Bingcheng; Yan, Yun; Huang, Jianbin; Kang, Wanli

2014-06-01

123

Morphological and nanomechanical behavior of supported lipid bilayers on addition of cationic surfactants.  

PubMed

The addition of surfactants to lipid bilayers is important for the modulation of lipid bilayer properties (e.g., in protein reconstitution and development of nonviral gene delivery vehicles) and to provide insight on the properties of natural biomembranes. In this work, the thermal behavior, organization, and nanomechanical stability of model cationic lipid-surfactant bilayers have been investigated. Two different cationic surfactants, hexadecyltrimethylammonium bromide (CTAB) and a novel derivative of the amino acid serine (Ser16TFAc), have been added (up to 50 mol %) to both liposomes and supported lipid bilayers (SLBs) composed by the zwitterionic phospholipid DPPC. The thermal phase behavior of mixed liposomes has been probed by differential scanning calorimetry (DSC), and the morphology and nanomechanical properties of mixed SLBs by atomic force microscopy-based force spectroscopy (AFM-FS). Although DSC thermograms show different results for the two mixed liposomes, when both are deposited on mica substrates similar trends on the morphology and the mechanical response of the lipid-surfactant bilayers are observed. DSC thermograms indicate microdomain formation in both systems, but while CTAB decreases the degree of organization on the liposome bilayer, Ser16TFAc ultimately induces the opposite effect. Regarding the AFM-FS studies, they show that microphase segregation occurs for these systems and that the effect is dependent on the surfactant content. In both SLB systems, different microdomains characterized by their height and breakthrough force Fb are formed. The molecular organization and composition is critically discussed in the light of our experimental results and literature data on similar lipid-surfactant systems. PMID:23782267

Lima, Lia M C; Giannotti, Marina I; Redondo-Morata, Lorena; Vale, M Luísa C; Marques, Eduardo F; Sanz, Fausto

2013-07-30

124

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

2013-10-01

125

Phase behavior in model homopolymer/CO2 and surfactant/CO2 systems: discontinuous molecular dynamics simulations.  

PubMed

Discontinuous molecular dynamics simulations are performed on surfactant (HmTn)/solvent systems modeled as a mixture of single-sphere solvent molecules and freely jointed surfactant chains composed of m slightly solvent-philic head spheres (H) and n solvent-philic tail spheres (T), all of the same size. We use a square-well potential to account for the head-head, head-solvent, tail-tail, and tail-solvent interactions and a hard-sphere potential for the head-tail and solvent-solvent interactions. We first simulate homopolymer/supercritical CO2 (scCO2) systems to establish the appropriate interaction parameters for a surfactant/scCO2 system. Next, we simulate surfactant/scCO2 systems and explore the effect of the surfactant volume fraction, packing fraction, and temperature on the phase behavior. The transition from the two-phase region to the one-phase region is located by monitoring the contrast structure factor of the equilibrated surfactant/scCO2 system, and the micelle to unimer transition is located by monitoring the aggregate size distribution of the equilibrated surfactant/scCO2 system. We find a two-phase region, a micelle phase, and a unimer phase with increasing packing fraction at fixed temperature or with increasing temperature at fixed packing fraction. The phase diagram for the surfactant/scCO2 system in the surfactant volume fraction-packing fraction plane and the density dependence of the critical micelle concentration are in qualitative agreement with experimental observations. The phase behavior of a surfactant/scCO2 system can be directly related to the solubilities of the corresponding homopolymers that serve as the head and tail blocks for the surfactant. The influence of surfactant structure (head and tail lengths) on the phase transitions is explored. PMID:15379475

Li, Zhengmin; Hall, Carol K

2004-09-28

126

Metal-ion retention properties of water-soluble amphiphilic block copolymer in double emulsion systems ( w\\/ o\\/ w) stabilized by non-ionic surfactants  

Microsoft Academic Search

Metal-ion retention properties of water-soluble amphiphilic polymers in presence of double emulsion were studied by diafiltration. Double emulsion systems, water-in-oil-in-water, with a pH gradient between external and internal aqueous phases were prepared. A poly(styrene-co-maleic anhydride) (PSAM) solution at pH 6.0 was added to the external aqueous phase of double emulsion and by application of pressure a divalent metal-ion stream was

Manuel Palencia; Bernabé L. Rivas

2011-01-01

127

Using tracer technique to study the flow behavior of surfactant foam.  

PubMed

Surfactant foam was used to remove absorbed hydrocarbons from soils. The nature and extent of the foam pathway decide the efficiency of this technology. The characteristics and behavior of foam flow are difficult to visually observe. In this study, laboratory sandbox experiments were performed to estimate the flow behavior of surfactant foam and thus elucidate the properties and flow behavior of surfactant foam. To quantitatively determine the distribution of foam and evaluate accurately the flow field of foam in the soil, this study designed a special technique, applying micro-scale iron powder as a tracer. The foam generated with 4% (w/v) mixed solution of Span 60 and sodium dodecyl sulfate (SDS) showed an excellent stability and quality, which made it particularly apt for this study. The results indicated that the foam flows through the zone above the clay planes and also flows through the zone between the clay planes. The heterogeneous sand does not inhibit the invasion of foam flow. Moreover, the results of tracer tests and photographs of the foam distributions in sandbox were identical in the behavior of foam flow. This knowledge is valuable for providing insight into the foam remediation of contaminated soil. PMID:19157697

Tsai, Yih-Jin; Chou, Feng-Chih; Cheng, Shin-Jen

2009-07-30

128

Electrochemically driven emulsion inversion  

NASA Astrophysics Data System (ADS)

It is shown that emulsions stabilized by ionic surfactants can be inverted by controlling the electrical potential across the oil-water interface. The potential dependent partitioning of sodium dodecyl sulfate (SDS) was studied by cyclic voltammetry at the 1,2-dichlorobenzene|water interface. In the emulsion the potential control was achieved by using a potential-determining salt. The inversion of a 1,2-dichlorobenzene-in-water (O/W) emulsion stabilized by SDS was followed by conductometry as a function of added tetrapropylammonium chloride. A sudden drop in conductivity was observed, indicating the change of the continuous phase from water to 1,2-dichlorobenzene, i.e. a water-in-1,2-dichlorobenzene emulsion was formed. The inversion potential is well in accordance with that predicted by the hydrophilic-lipophilic deviation if the interfacial potential is appropriately accounted for.

Johans, Christoffer; Kontturi, Kyösti

2007-09-01

129

Pressure effects on the phase behavior of a propylene/water/surfactant mixture  

SciTech Connect

The phase behavior of the propylene/water/Tergitol 7 surfactant ternary mixture has been examined as a function of pressure at 25.5C. Unlike conventional liquid alkane based systems, a three-phase region is obtained in the absence of added electrolyte. This is likely due to a higher upper critical solution temperature for the propylene/Tergitol 7 binary mixture, in comparison to that for mixtures of various anionic surfactants and liquid alkanes. The effect of increasing pressure is similar to the effect of decreasing temperature or increasing electrolyte concentration, according to the Kahlweit phenomenological model for amphiphile/water/oil phase behavior (as well as models describing effects on interfacial curvature, such as the R ratio). The conductivities of the nominally propylene-continuous upper phases in the systems examined are high enough to suggest electrical percolation, implying the presence of significant volume fractions of micelles in these phases.

Beckman, E.J. (Univ. of Pittsburgh, PA (United States)); Smith, R.D. (Pacific Northwest Labs., Richland, WA (United States))

1991-04-18

130

Pressure effects on the phase behavior of a propylene\\/water\\/surfactant mixture  

Microsoft Academic Search

The phase behavior of the propylene\\/water\\/Tergitol 7 surfactant ternary mixture has been examined as a function of pressure at 25.5C. Unlike conventional liquid alkane based systems, a three-phase region is obtained in the absence of added electrolyte. This is likely due to a higher upper critical solution temperature for the propylene\\/Tergitol 7 binary mixture, in comparison to that for mixtures

Eric J. Beckman; Richard D. Smith

1991-01-01

131

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

132

Nonionic surfactants with linear and branched hydrocarbon tails: compositional analysis, phase behavior, and film properties in bicontinuous microemulsions.  

PubMed

Nonionic alcohol ethoxylates are widely used as surfactants in many different applications. They are available in a large number of structural varieties as technical grade products. This variety is mainly based on the use of different alcohols, which can be linear or branched and contain primary, secondary, or tertiary OH groups. Technical grade products are poorly defined as they are composed of alcohol mixtures being different in chain length and structure. On the other hand, monodisperse alcohol ethoxylates are commercially available; however, these surfactants exist only with primary and linear alcohols. In the field of microemulsion research the monodisperse alcohol ethoxylates are widely used. The phase behavior and film properties of these surfactants were studied intensively with respect to the size of the hydrophilic and hydrophobic moieties. Due to the lack of appropriate model surfactants until now, there is little information on how the structure of the hydrocarbon tail influences the microemulsion behavior. To examine structural influences, we synthesized a series of surfactants with the composition C10E5 and having different linear and branched hydrocarbon tails. The surfactants were monodisperse with respect to the hydrocarbon tail but polydisperse with respect to the ethoxylation degree. However, a detailed characterization showed that they were similar concerning the average ethoxylation degree and EO chain length distribution. The phase behavior was investigated for bicontinuous microemulsions, and the film properties were analyzed by small-angle neutron scattering (SANS). Our results show that the structure of the hydrocarbon tail strongly influences the microemulsion behavior. The most efficient surfactant is obtained if the hydrocarbon tail is linear and the hydrophilic group is attached in the C-1 position. Surfactants having the hydrophilic group bound to the C-2 or C-4 position or which contain a branched hydrocarbon tail are less efficient and exhibit in most cases visibly lower phase inversion temperatures. Both the efficiency and temperature behavior mainly can be explained on the basis of increased bulkiness of the branched structures compared to the fully linear version. The phase behavior results are largely confirmed by the SANS investigations. Those results show that the fully linear surfactant exhibits the most rigid interfacial film. In additional experiments this surfactant was compared with its monodisperse analogue. According to the phase diagrams, the surfactant having the polydisperse hydrophilic moiety is drastically more efficient although the film stiffnesses are almost identical. PMID:17489617

Frank, Christian; Frielinghaus, Henrich; Allgaier, Jürgen; Prast, Hartmut

2007-06-01

133

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

2013-11-15

134

Inversion of heavy crude oil-in-brine emulsions  

Microsoft Academic Search

The inversion of heavy crude oil in brine emulsions stabilized with nonionic surfactants has been studied experimentally. Most of the tests were carried out in beakers and in a cone and plate viscometer with the cone displaced at some distance from the plate. The effects of shear rate, surfactant species and concentration, temperature and oil fraction on emulsion inversion were

R. Sun; C. A. Shook

1996-01-01

135

Spin-glass-like behavior of surfactant capped Co50Ni50 nanoparticles  

NASA Astrophysics Data System (ADS)

We investigated static and dynamic magnetic properties of surfactant capped 25 nm Co50Ni50 particles. These nanoparticles exhibit the superparamagnetic behavior at 300 K. Interestingly, a freezing temperature (Tf ˜ 16 K) is observed in the ZFC curve, which corresponds to surface spin-glass-like transition. The significant high coericivity (Hc ˜ 910 Oe) is observed at 5 K as compared to Hc ˜ 180 Oe at 77 K and is attributed to the random freezing of surface spins at T ? Tf. The spin-glass-like behavior of nanoparticles is further verified by ac-susceptibility measurements as a function of temperature at different frequencies. The fits of Arrhenius law, Vogel-Fulcher law and dynamic scaling equation to data confirm the spin-glass-like behavior of Co50Ni50 nanoparticles.

Sharma, Sachil; Ningthoujam, Raghumani S.; Gajbhiye, Namdeo S.

2013-02-01

136

Drops and emulsions with complex interfaces  

NASA Astrophysics Data System (ADS)

We study the behavior of emulsion drops in external flow fields, focusing on recent experimental work involving liquid interfaces covered with surface-active species, in particular adsorbed proteins and particles. Three different length scales are considered: (i) the rheology of complex interfaces is discussed for adsorbed polyelectrolyte surfactants with different molecular structure (compact and globular vs. random coil); (ii) the flow of single drops with macromolecular adsorption layers is studied in optical flow cells; (iii) dilute emulsions of drops are investigated using rheo-small angle light scattering (rheo-SALS). We discuss the results in the context of emulsion and drop models accounting for interfacial viscoelasticity, as well as with capsule suspension models for the case of rigid interfacial layers. Drops stabilized by adsorbed particles or globular proteins can be understood as capsules surrounded by a soft shell; their behavior on the single drop level is in many ways reminiscent of phenomena observed with red blood cells or vesicles, including non-linear drop shape fluctuations under creeping flow conditions. References: [1] Fischer P, Erni P. Curr Opin Colloid Interface Sci (2007, accepted) [2] Erni P et al., Appl Phys Lett 87, 244104 (2007)

Erni, Philipp; Windhab, Erich J.; Fischer, Peter

2007-11-01

137

Solubilization in monodisperse emulsions.  

PubMed

The kinetics of oil solubilization into micelles from nearly monodisperse alkane-in-water emulsion droplets was investigated. Emulsions containing either hexadecane or tetradecane oils were fractionated to be narrowly distributed, using a method developed by Bibette [J. Bibette, J. Colloid Interface Sci. 147 (1991) 474]. These monodisperse emulsions were mixed with SDS or Tween 20 aqueous micellar solutions of various concentrations. Time-dependent solubilization was monitored using light scattering and a decrease in average droplet size over time was observed, in contrast to what has been observed previously with polydisperse emulsions. The rate at which the droplet size decreased was found to be independent of the initial droplet size. Turbidity measurements were also used to track the solubilization kinetics, and a population balance analysis used on both types of measurements to extract effective mass transfer coefficients. The dependence of these transfer coefficients on droplet size, alkane type, surfactant type and concentration provide insights into plausible mechanisms of emulsion droplet solubilization within micellar solutions. PMID:17603068

Ariyaprakai, Suwimon; Dungan, Stephanie R

2007-10-15

138

Metal-ion retention properties of water-soluble amphiphilic block copolymer in double emulsion systems (w/o/w) stabilized by non-ionic surfactants.  

PubMed

Metal-ion retention properties of water-soluble amphiphilic polymers in presence of double emulsion were studied by diafiltration. Double emulsion systems, water-in-oil-in-water, with a pH gradient between external and internal aqueous phases were prepared. A poly(styrene-co-maleic anhydride) (PSAM) solution at pH 6.0 was added to the external aqueous phase of double emulsion and by application of pressure a divalent metal-ion stream was continuously added. Metal-ions used were Cu(2+) and Cd(2+) at the same pH of polymer solution. According to our results, metal-ion retention is mainly the result of polymer-metal interaction. Interaction between PSMA and reverse emulsion globules is strongly controlled by amount of metal-ions added in the external aqueous phase. In addition, as metal-ion concentration was increased, a negative effect on polymer retention capacity and promotion of flocculation phenomena were produced. PMID:21855082

Palencia, Manuel; Rivas, Bernabé L

2011-11-15

139

Kinetic study of aggregation of milk protein and/or surfactant-stabilized oil-in-water emulsions by sedimentation field-flow fractionation.  

PubMed

Milk proteins are able to facilitate the formation and stabilization of oil droplets in food emulsions. This study employed Sedimentation Field-Flow Fractionation (SdFFF) to monitor changes in particle size distribution of freshly prepared emulsions with varying weight contributions of sodium caseinate (SC) and whey protein concentrate (WPC). The effect of the addition of Tween 80 (T) on the initial droplet size was also investigated. The results indicated that emulsifying ability follows the order Tween 80>WPC>SC, with corresponding weight average droplet diameter of 0.319, 0.487 and 0.531?m respectively, when each of the above emulsifiers was used solely. The stability of sodium caseinate emulsions was studied at 30.5 and 80.0°C by measuring the particle size distribution for a period of 70h. Emulsions withstood the temperatures and exhibited an initial increase in particle size distribution caused by heat-induced droplet aggregation, followed by a decrease to approximately the initial droplet size. The rate of droplet aggregation depends on the severity of thermal processing, as revealed by the kinetics of particle aggregation during aging at different temperatures. Comparison of the experimental rate constants found from SdFFF, with those determined theoretically gives invaluable information about the oil droplet stability and the aggregation mechanism. Based on the proposed mechanistic scheme various physicochemical quantities, which are very important in explaining the stability of oil-in-water emulsions, were determined. Finally, the advantages of SdFFF in studying the aggregation of the oil-in-water droplets, in comparison with other methods used for the same purpose, are discussed. PMID:23899382

Kenta, Stella; Raikos, Vassilios; Vagena, Artemis; Sevastos, Dimitrios; Kapolos, John; Koliadima, Athanasia; Karaiskakis, George

2013-08-30

140

Shape-Changing and Amphiphilicity-Reversing Janus Particles with pH-Responsive Surfactant Properties.  

PubMed

Janus particles are biphasic colloids that have two sides with distinct chemistry and wettability. Because of their amphiphilicity, Janus particles present a unique opportunity for stabilizing multiphasic fluid mixtures such as emulsions. Our work is motivated by one class of molecular amphiphiles that change their surfactant properties in response to environmental stimuli. Depending on the environmental conditions, these stimuli-responsive molecular amphiphiles are able to assemble into different structures, generate emulsions with different morphologies, and also induce phase inversion emulsification. We present a new synthesis method utilizing a combination of polymerization-induced phase separation and seeded emulsion polymerization, which allows for the bulk synthesis of highly uniform pH-responsive Janus particles that are able to completely reverse their surfactant properties in response to solution pH. One side of these Janus particles is rich in a hydrophobic monomer, styrene, whereas the other side is rich in a pH-sensitive hydrophilic repeating unit, acrylic acid. These Janus particles change their aggregation/dispersion behavior and also transform into different shapes in response to pH changes. Furthermore, we demonstrate that these Janus particles can stabilize different types of emulsions (oil-in-water and water-in-oil) and, more importantly, induce phase inversion of emulsions in response to changes in solution pH. The pH-responsive aggregation/dispersion behavior of these Janus particles also allows us to tune the interactions between oil-in-water emulsion droplets without inducing destabilization; that is, emulsion drops with attractive or repulsive interactions can be generated by changing the pH of the aqueous phase. Our study presents a new class of colloidal materials that will further widen the functionality and properties of Janus particles as dynamically tunable solid surfactants. PMID:24791976

Tu, Fuquan; Lee, Daeyeon

2014-07-16

141

Influence of clay addition on the properties of olive oil in water emulsions  

Microsoft Academic Search

The behaviour of olive oil-in-water emulsions (O\\/W) was studied in the presence of smectite particles. The distribution of these particles in the emulsions and the effect of their interaction with the surfactant on the stability of the emulsions were investigated. Whereas the variation of surfactant and\\/or clay content did not seem to affect the nature of the emulsion, it had

H. Nciri; M. Benna-Zayani; M. Stambouli; N. Kbir-Ariguib; M. Trabelsi-Ayadi; V. Rosilio; J.-L. Grossiord

2009-01-01

142

A novel method to quantify the amount of surfactant at the oil\\/water interface and to determine total interfacial area of emulsions  

Microsoft Academic Search

We present a methodology to quantitatively determine the fraction of sodium dodecyl sulfate (SDS) that partitions to the oil\\/water interface in oil-in-water macroemulsions and calculate the total interfacial area (TIA) through the novel use of filtration through nanoporous membranes. Ultrafiltration was carried out in centrifuge tubes having nanoporous filters with a 30,000 molecular weight cutoff (MWCO), so that emulsion droplets

Monica A. James-Smith; Kile Alford; Dinesh O. Shah

2007-01-01

143

Spontaneous formation of gel emulsions in organic solvents and commercial fuels induced by a novel class of amino acid derivatized surfactants.  

PubMed

A novel class of amphiphiles, sodium N-(n-dodecyl-2-aminoethanoyl)-l-amino acidate, have been synthesized. These amphiphiles have been shown to form oil-in-water-type gel emulsions with a high internal-phase ratio in organic solvents as well as in commercial fuels simply by agitation. No heating and cooling cycle was required for the formation of gels. The amphiphiles also showed efficient phase-selective gelation in the presence of excess water. The minimum gelator concentrations for the amphiphiles in the solvents employed have been determined. The effects of the chain length of the hydrocarbon tail and the chirality of a representative amphiphile on its ability to promote gelation in a given organic solvent have been investigated. Also, the effect of acid and alkali on the gelation has been examined. The optical microscopic picture of the gel emulsion showed foamlike structures with oil compartments separated by the continuous aqueous phase. The mechanism of the formation of gel emulsions has been discussed. PMID:15620291

Khatua, Dibyendu; Dey, Joykrishna

2005-01-01

144

Phase behavior of gemini surfactant hexylene-1,6-bis(dodecyldimethylammonium bromide) and polyelectrolyte NaPAA.  

PubMed

The phase behavior of aqueous mixtures of gemini surfactant hexylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) and oppositely charged polyelectrolyte sodium polyacrylate (NaPAA) has been studied experimentally. Compared to the mixtures of the traditional surfactant dodecyltrimethylammonium bromide (DTAB) and NaPAA, the gel phase region in the 12-6-12/NaPAA solution is larger. Element analysis reveals that NaPAA in the gel phase tends to replace the counterions of surfactant micelle and to release its own counterions. Spherical aggregates are observed in either top or bottom gel phase as detected by transmission electron microscopy. The addition of sodium bromide (NaBr) leads to a decrease in the gel phase region and the occurrence of a new cream phase. PMID:16481000

Pi, Yingying; Shang, Yazhuo; Peng, Changjun; Liu, Honglai; Hu, Ying; Jiang, Jianwen

2006-07-01

145

Experimental and theoretical approach to aggregation behavior of new di-N-oxide surfactants in an aquatic environment.  

PubMed

A homologous series of new dicephalic type surfactants (N,N-bis3,3'-(dimethylamino)propyl]alkylamide di-N-oxides) were synthesized and their aggregation phenomena were extensively studied. First, the pH-sensitivity of the investigated surfactants was tested in potentiometric titrations. Then, the adsorption isotherms were measured and interpreted using the Gibbs adsorption equation to determine physicochemical properties. The spin probe EPR technique was employed to monitor the micellization behavior of the surfactants, depending on temperature and surfactant concentration. Critical micelle concentrations (CMC) were determined through an analysis of the calculated spin probe rotational correlation times. A greater insight into the local microenvironment of the formed aggregates was gained by analyzing the properties of the immobilized spin probes. In addition, the CMC values were compared with the ones obtained from tensiometry measurements (taking into account the contributions of the various ionic and nonionic surfactant forms). The approximate size of the micellar aggregates was estimated by the dynamic light scattering (DLS) method. Good agreement between the experimental hydrodynamic radii and those predicted using density functional theory (DFT) guaranteed that the subsequently calculated aggregation numbers, representing the number of molecules in a micelle, were close to the real values. Moreover, the theoretical QSAR methods were used to determine the shape of the micelles via the prediction of the critical packing parameter (CPP). PMID:23098238

Lewi?ska, Agnieszka; Witwicki, Maciej; Fr?ckowiak, Renata; Jezierski, Adam; Wilk, Kazimiera A

2012-12-13

146

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

147

Unstable topography of biphasic surfactant monolayers  

NASA Astrophysics Data System (ADS)

We study the conformation of a heterogeneous surfactant monolayer at a fluid-fluid interface, near a boundary between two lateral regions of differing elastic properties. The monolayer attains a conformation of shallow, steep "mesas" with a height difference of up to 10 nm. If the monolayer is progressively compressed (e.g.,in a Langmuir trough), the profile develops overhangs and finally becomes unstable at a surface tension of about K(?c0)2, where ?c0 is the difference in spontaneous curvature and K a bending stiffness. We discuss the relevance of this instability to recently observed folding behavior in lung surfactant monolayers, and to the absence of domain structures in films separating oil and water in emulsions.

Diamant, H.; Witten, T. A.; Gopal, A.; Lee, K. Y. C.

2000-10-01

148

Emulsion Polymers  

NASA Astrophysics Data System (ADS)

The symposium "Emulsion Polymers" was held at the 217th American Chemical Society (ACS) Meeting in Anaheim, CA in March 1999. Topic areas presented included novel concepts in emulsion and miniemulsion homo- and copolymerization, the role of polymeric stabilizers in emulsion polymerization, particle morphology and film formation, and applications of latex systems. The papers in this volume of Macromolecular Symposia cover a broad range of topics characteristic of the symposium.

El-Aasser, Mohamed S.; Smith, Carrington D.; Meisel, I.; Spiegel, S.; Kniep, C. S.

2000-08-01

149

Effect of shear flow on the phase behavior of an aqueous gelatin-dextran emulsion.  

PubMed

A rheo-optical methodology, based on small angle light scattering and transmitted light intensity measurements, has been used to study in situ and on a time resolved basis the shear induced morphology in ternary two-phase water-gelatin-dextran mixtures. Emulsions close to the binodal line as well as far from it have been investigated. It is shown that above a critical shear rate, shear-induced mixing occurs at the length scales probed by the laser light. It is hypothesized that the shear-induced homogenization is due to the shear forces that exceed the intermolecular forces of the self-association process of the gelatin. The isothermal phase diagram at a fixed shear rate has been determined. In addition, the structure evolution after cessation of flow has been studied. When flow is stopped after homogenization, phase separation occurs almost instantaneously. When subsequently applying a low shear rate, the structure coarsens due to coalescence of the dispersed droplets. The kinetics of this coalescence process is strain controlled. PMID:15002985

Antonov, Y A; Van Puyvelde, P; Moldenaers, P; Leuven, K U

2004-01-01

150

Optimum Formulation of Surfactant\\/Water\\/Oil Systems for Minimum Interfacial Tension or Phase Behavior  

Microsoft Academic Search

A screening test used to help select surfactant systems potentially effective for oil recovery is to identify those formulations that yield middle-phase microemulsions when mixed with sufficient quantities of oil and brine. A correlation is presented to link these variables regarding their contributions to middle-phase formation: structure of the sulfonated surfactant, alkane carbon number (ACN), and alcohol type and concentration.

J. L. Salager; J. C. Morgan; R. S. Schechter; W. H. Wade; E. Vasquez

1979-01-01

151

Effect of salinity and alcohol partitioning on phase behavior and oil displacement efficiency in surfactant-polymer flooding  

Microsoft Academic Search

The equivalent alkane carbon number (EACN) of a crude oil, namely Ankleshwar crude, is successfully modeled by a mixture of\\u000a pure alkanes. The EACN of the crude oil is found to be 9.3, and an appropriate mixture of nonane and decane exhibited phase\\u000a behavior similar to that of the crude oil. A surfactant system for a water flooded reservoir at

Y. K. Pithapurwala; A. K. Sharmab; D. O. Shah

1986-01-01

152

Combined effect of nonionic surfactant Tween 80 and DOM on the behaviors of PAHs in soil–water system  

Microsoft Academic Search

Batch experiments were performed to examine the desorption behavior of phenanthrene and pyrene in soil–water system in the presence of nonionic surfactant Tween 80 and dissolved organic matter (DOM) derived from pig manure or pig manure compost. Addition of 150mgl?1 Tween 80 desorbed 5.8% and 2.1% of phenanthrene and pyrene from soil into aqueous phase, respectively, while the addition of

K. Y. Cheng; J. W. C. Wong

2006-01-01

153

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

154

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

155

Transfer of Oil between Emulsion Droplets  

PubMed

A contrast matching technique was used to determine the exchange of oils between emulsion droplets having different refractive indexes. Emulsions of tetradecane and 1-bromo tetradecane in water were made separately in a high-pressure homogenizer, then mixed and equilibrated at rest. It was found that droplets exchanged oil molecules through the continuous phase, in a process similar to Ostwald ripening. Emulsions of hexadecane and 1-bromo hexadecane were also mixed; at rest, no exchange of oil took place. These mixtures were subsequently recirculated in the high-pressure homogenizer. Exchange of oil occurred as a result of droplet coalescence in the homogenizer. Two regimes were found, "surfactant-poor" and "surfactant-rich." In the "surfactant-poor" regime, recoalescence took place at all values of the pressure used in the homogenizer. In the "surfactant-rich" regime, recoalescence took place only if the pressure was at least equal to that used originally to make the emulsion. These results demonstrate that the size of the emulsion droplets made in a high-pressure homogenizer results from a succession of fragmentation and recoalescence processes. Possible mechanisms preventing recoalescence are discussed. PMID:8978540

Taisne; Walstra; Cabane

1996-12-25

156

Studies on emulsion liquid membrane extraction of cephalexin  

Microsoft Academic Search

An experimental study on batch extraction of cephalexin using an emulsion liquid membrane system has been reported. The effects of surfactant, carrier and solute concentrations, phase volume ratio, stirring speed, and counterion concentration on the extraction rate were examined. Surfactant, carrier and diluent used were Span-80, Aliquat-336 and n-heptane–kerosene (1:1), respectively. Under the optimised experimental conditions, emulsion swelling was found

G. C Sahoo; N. N Dutta

1998-01-01

157

Effects of Abrasive Size and Surfactant Concentration on the Non-Prestonian Behavior of Ceria Slurry in Shallow Trench Isolation Chemical Mechanical Polishing  

NASA Astrophysics Data System (ADS)

We examined the dependence of a non-Prestonian behavior on surfactant concentrations in ceria slurries that contained abrasives of various sizes by performing chemical mechanical polishing (CMP) tests using blank wafers. We found that both the surfactant concentrations and the slurry abrasive sizes influence the non-Prestonian behavior. In this paper, we explain in detail a factor that can be used to quantify relation on the non-Prestonian behavior of a slurry, ?NP. This non-Prestonian factor ?NP was determined to be almost independent of the surfactant concentration in slurry A (large abrasive), but increased with the surfactant concentrations in slurries B (medium-sized abrasive) and C (small abrasive).

Kang, Hyun-Goo; Katoh, Takeo; Park, Hyung-Soon; Paik, Ungyu; Park, Jea-Gun

2005-01-01

158

Effects of calcium ions on solubility and aggregation behavior of an anionic sulfonate gemini surfactant in aqueous solutions.  

PubMed

Effects of calcium ions on the solubility and aggregation behavior of an anionic sulfonate gemini surfactant 1,3-bis(N-dodecyl-N-propylsulfonate sodium)-propane (12-3-12(SO(3))(2)) have been studied in aqueous solution. Compared with single-chain surfactant sodium dodecylsulfate, 12-3-12(SO(3))(2) shows much better performance to the hardness tolerance with calcium ions. Moreover aggregates of the Ca(2+)/12-3-12(SO(3))(2) complexes in clear solutions influence the morphologies of the precipitates. At 12-3-12(SO(3))(2) concentrations lower than 1.5 mM, the small spherical micelles of Ca(2+)/12-3-12(SO(3))(2) in clear solutions generate precipitates of solid particles owing to complexation of surfactant monomers with Ca(2+). At 12-3-12(SO(3))(2) concentrations higher than 1.5mM, the Ca(2+)/12-3-12(SO(3))(2) complexes transform into large compact spherical aggregates and then into long wormlike micelles. These large aggregates are well dispersed in aqueous solutions and efficiently complex calcium ions. In particular, long wormlike micelles are entangled with each other at 100.0 mM CaCl(2) and 100.0 mM 12-3-12(SO(3))(2) exhibiting viscoelastic properties. In addition, the stacking of long wormlike micelles produces precipitates with ordered fibrillar structures. This work reveals that such anionic sulfonate gemini surfactants are better candidates than single-chain surfactants in applications with high hardness levels, and the ordered aggregate structures may have potential applications in materials science. PMID:22682325

Yu, Defeng; Wang, Yingxiong; Zhang, Jian; Tian, Maozhang; Han, Yuchun; Wang, Yilin

2012-09-01

159

One F-octyl versus two F-butyl chains in surfactant aggregation behavior.  

PubMed

An easy synthetic procedure in two or three steps from perfluoroalkylethyl iodide derivatives led to six novel fluorinated carboxylates monomeric and gemini surfactants with one or two hydrophobic tails, respectively: RF(C2H4)CH(CO2(-))2,2Na(+) and [RF(C2H4)]2C(CO2(-)),Na(+), where RF = C4F9, C6F13, and C8F17. These anionic surfactants exhibited very low surface tension from 15 to 33 mN/m as well as low critical micelle concentration until 1.3 × 10(-4) mol/L. Furthermore, the surface properties of the gemini compound with two short fluoroalkyl chains (RF = C4F9) were found to be almost equal to those of the monomeric surfactant with one long fluoroalkyl chain (RF = C8F17), which could provide an interesting alternative to the bioaccumulative long-chain perfluorinated surfactant. PMID:24188050

Dramé, Abdoulaye; Taffin de Givenchy, Elisabeth; Dieng, Samba Yandé; Amigoni, Sonia; Oumar, Mamadou; Diouf, Alioune; Darmanin, Thierry; Guittard, Frédéric

2013-12-01

160

Dynamic behavior of supramolecular comb polymers consisting of poly(2-vinyl pyridine) and palladium-pincer surfactants in the solid state.  

PubMed

When poly(2-vinyl pyridine) is combined with Pd-pincer-based organometallic surfactants, a mesomorphic structure forms due to weak stacking interactions between the pyridine units and the Pd-pincer headgroups. The weak binding between the surfactant and the polymer competes with the tendency of the aliphatic tails of the surfactant to crystallize. Here, we demonstrate that over extended periods of incubation, the crystallization tendency of the surfactant tails causes the surfactant molecules to detach from the polymer and gives rise to additional packing modes of the alkyl tails featuring higher crystalline order. The dynamic behavior of these aged structures was investigated by variable-temperature small-angle X-ray scattering (SAXS) and solid-state (13) C?NMR, and revealed the influence of thermal changes on the molecular level, and how these changes propagate to the mesoscale structure. PMID:24827547

Davidi, Inbal; Hermida-Merino, Daniel; Keinan-Adamsky, Keren; Portale, Giuseppe; Goobes, Gil; Shenhar, Roy

2014-06-01

161

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

Microsoft Academic Search

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

P. Somasundaran

2002-01-01

162

Influence of interfacial rheology on foam and emulsion properties  

Microsoft Academic Search

Foams and emulsions are stabilized by surfactant monolayers that adsorb at the air–water and oil–water interfaces, respectively. As a result of monolayer adsorption, the interfaces become viscoelastic. We will describe experiments showing that foaming, emulsification, foam and emulsion stability, are strongly dependent upon the value of compression elasticity and viscosity. This will include excited surface wave devices for the measurement

D Langevin

2000-01-01

163

Characterization of Phase and Emulsion Behavior, Surfactant Retention, and Oil Recovery for Novel Alcohol Ethoxycarboxylate Surfactants. Final Report, October 1, 1997-August 31, 2001.  

National Technical Information Service (NTIS)

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...

L. T. Moeti R. Sampath

2001-01-01

164

Adsorption behavior of hydrophobin and hydrophobin/surfactant mixtures at the solid-solution interface.  

PubMed

The adsorption of surface-active protein hydrophobin, HFBII, and HFBII/surfactant mixtures at the solid-solution interface has been studied by neutron reflectivity, NR. At the hydrophilic silicon surface, HFBII adsorbs reversibly in the form of a bilayer at the interface. HFBII adsorption dominates the coadsorption of HFBII with cationic and anionic surfactants hexadecyltrimethyl ammonium bromide, CTAB, and sodium dodecyl sulfate, SDS, at concentrations below the critical micellar concentration, cmc, of conventional cosurfactants. For surfactant concentrations above the cmc, HFBII/surfactant solution complex formation dominates and there is little HFBII adsorption. Above the cmc, CTAB replaces HFBII at the interface, but for SDS, there is no affinity for the anionic silicon surface hence there is no resultant adsorption. HFBII adsorbs onto a hydrophobic surface (established by an octadecyl trimethyl silane, OTS, layer on silicon) irreversibly as a monolayer, similar to what is observed at the air-water interface but with a different orientation at the interface. Below the cmc, SDS and CTAB have little impact upon the adsorbed layer of HFBII. For concentrations above the cmc, conventional surfactants (CTAB and SDS) displace most of the HFBII at the interface. For nonionic surfactant C(12)E(6), the pattern of adsorption is slightly different, and although some coadsorption at the interface takes place, C(12)E(6) has little impact on the HFBII adsorption. PMID:21797273

Zhang, Xiaoli L; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Bent, Julian; Cox, Andrew

2011-09-01

165

Preparation and self-assembly behavior of ?-sheet peptide-inserted amphiphilic block copolymer as a useful polymeric surfactant.  

PubMed

A hybridization of structurally regulated biopolymers and conventional synthetic polymers offers promising opportunities to design novel polymeric nanomaterials. In this study, we newly prepared an amphiphilic triblock copolymer with ?-sheet forming peptide as a central block, polystyrene-block-tetra(leucine)-block-poly(ethylene glycol) (PS-L4-PEG), by combining the solid phase peptide synthesis with the atom transfer radical polymerization (ATRP). On the basis of several morphological and structural analyses using atomic force microscopy, transmission electron microscopy, FTIR spectroscopy, and contact angle measurement, the PS-L4-PEG was found to form PEG-shell spherical and/or elliptical vesicles with a diameter of 30-100 nm in aqueous medium. By contrast, the PS-L4-PEG self-assembled into PS-shell spherical aggregates in toluene, which is good solvent for both PEG and PS. In both cases, the central peptide formed a ?-sheet network in the nanoassemblies. Furthermore, the PS-L4-PEG was found to stabilize a water-in-oil emulsion remarkably in comparison with the PS-PEG diblock copolymer, demonstrating the potential of this peptide-polymer hybrid as a useful polymeric surfactant. PMID:24289247

Koga, Tomoyuki; Kamiwatari, Soichi; Higashi, Nobuyuki

2013-12-17

166

O\\/W\\/O Multiple Emulsions via One?Step Emulsification Process  

Microsoft Academic Search

The preparation of O\\/W\\/O multiple emulsions by a one?step emulsification process was studied using an optical microscope equipped with a camera. The O\\/W\\/O multiple emulsions could be prepared by the introduction of two surfactants and two polymers. But when one of two polymers or water?soluble surfactant was not added, W\\/O emulsions with various size distributions were formed. Tween 20 added

Chul Oh

2004-01-01

167

Fluorescence studies of associative behavior of cationic surfactant moieties covalently linked to poly(acrylamide) at the surfactant head or tail  

Microsoft Academic Search

Association properties of hydrophobically modified water-soluble polymers bearing the same (or similar) hydrophobic and charged groups at different relative positions (with respect to the polymer main chain) were compared. Two types of surfactant monomers (surfmers) were synthesized; a cationic surfactant was linked to the p-position of styrene at the surfactant charged head (dimethyldodecyl-4-vinylbenzylammonium chloride (St-QC12)) or at the tail end

Hiromi Morimoto; Akihito Hashidzume; Yotaro Morishima

2003-01-01

168

Adsorption behavior of hydrophobin and hydrophobin/surfactant mixtures at the air-water interface.  

PubMed

The adsorption of the surface-active protein hydrophobin, HFBII, and the competitive adsorption of HFBII with the cationic, anionic, and nonionic surfactants hexadecyltrimethylammonium bromide, CTAB, sodium dodecyl sulfate, SDS, and hexaethylene monododecyl ether, C(12)E(6), has been studied using neutron reflectivity, NR. HFBII adsorbs strongly at the air-water interface to form a dense monolayer ?30 Å thick, with a mean area per molecule of ?400 Å(2) and a volume fraction of ?0.7, for concentrations greater than 0.01 g/L, and the adsorption is independent of the solution pH. In competition with the conventional surfactants CTAB, SDS, and C(12)E(6) at pH 7, the HFBII adsorption totally dominates the surface for surfactant concentrations less than the critical micellar concentration, cmc. Above the cmc of the conventional surfactants, HFBII is displaced by the surfactant (CTAB, SDS, or C(12)E(6)). For C(12)E(6) this displacement is only partial, and some HFBII remains at the surface for concentrations greater than the C(12)E(6) cmc. At low pH (pH 3) the patterns of adsorption for HFBII/SDS and HFBII/C(12)E(6) are different. At concentrations just below the surfactant cmc there is now mixed HFBII/surfactant adsorption for both SDS and C(12)E(6). For the HFBII/SDS mixture the structure of the adsorbed layer is more complex in the region immediately below the SDS cmc, resulting from the HFBII/SDS complex formation at the interface. PMID:21774529

Zhang, Xiaoli L; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Bent, Julian; Cox, Andrew; Campbell, Richard A

2011-09-20

169

Polyelectrolyte and surfactant mixed solutions. behavior at surfaces and in thin films.  

PubMed

Dilute mixed solutions of non-surface active anionic polymers (polyacrylamide and polystyrene sulfonate, xanthan) and various surfactants have been studied with several methods: surface tension, ellipsometry, X-ray and neutron reflectivity, thin film balance, surface and bulk rheology. A strong synergistic lowering of the surface tension is found with cationic surfactants in the concentration range where no appreciable complexation of surfactant and polymer occurs in the bulk solution (as seen from viscosity measurements). Despite appreciable differences between surface tension behaviour, the adsorbed layer is very similar for all the polymers: their thickness is small and the polymer chains are stretched along the surface. The surface tension behaviour of these polymers with non-ionic surfactants is also different. When the polymers are confined in thin films, the forces between surfaces are similar, and independent of surfactant nature: oscillatory forces are measured, which reflect the existence of a polymer network with a well defined mesh size. The connection of foam stability with surface and bulk complexation is far from clear. PMID:11215810

Langevin, D

2001-01-29

170

Effect of surfactants on single bubble sonoluminescence behavior and bubble surface stability  

NASA Astrophysics Data System (ADS)

The effect of surfactants on the radial dynamics of a single sonoluminescing bubble has been investigated. Experimentally, it is observed that an increase in the surfactant concentration leads to a decline in the oscillation amplitude and hence light emission intensity. Numerical simulations support this result, showing that under the driving pressures required to achieve single bubble sonoluminescence (SBSL), the surface properties, namely, the surface elasticity and dilatational viscosity, contribute to the damping of the radial amplitude in the bubble oscillation. In most cases this stabilizes the bubble surface, and contributes to a decreased light intensity. A stronger driving pressure is necessary to achieve equivalent light emission to a surfactant-free bubble. However, as the driving pressure is increased, the surface stability also decreases, making it practically very difficult for a bubble to achieve high SBSL intensities in concentrated surfactant solutions. Although more stable owing to more mild pulsations, the instability mechanism for a surfactant-coated bubble at higher ambient radii is more likely to be of the Rayleigh-Taylor type than that of a clean bubble at the same given acoustic parameters, which can lead to bubble disintegration before correcting mechanisms can bring the bubble back into the stable sonoluminescence regime.

Leong, Thomas; Yasui, Kyuichi; Kato, Kazumi; Harvie, Dalton; Ashokkumar, Muthupandian; Kentish, Sandra

2014-04-01

171

Effect of surfactants on single bubble sonoluminescence behavior and bubble surface stability.  

PubMed

The effect of surfactants on the radial dynamics of a single sonoluminescing bubble has been investigated. Experimentally, it is observed that an increase in the surfactant concentration leads to a decline in the oscillation amplitude and hence light emission intensity. Numerical simulations support this result, showing that under the driving pressures required to achieve single bubble sonoluminescence (SBSL), the surface properties, namely, the surface elasticity and dilatational viscosity, contribute to the damping of the radial amplitude in the bubble oscillation. In most cases this stabilizes the bubble surface, and contributes to a decreased light intensity. A stronger driving pressure is necessary to achieve equivalent light emission to a surfactant-free bubble. However, as the driving pressure is increased, the surface stability also decreases, making it practically very difficult for a bubble to achieve high SBSL intensities in concentrated surfactant solutions. Although more stable owing to more mild pulsations, the instability mechanism for a surfactant-coated bubble at higher ambient radii is more likely to be of the Rayleigh-Taylor type than that of a clean bubble at the same given acoustic parameters, which can lead to bubble disintegration before correcting mechanisms can bring the bubble back into the stable sonoluminescence regime. PMID:24827332

Leong, Thomas; Yasui, Kyuichi; Kato, Kazumi; Harvie, Dalton; Ashokkumar, Muthupandian; Kentish, Sandra

2014-04-01

172

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

173

Formation of fluid heavy oil-in-water emulsions for pipeline transportation  

Microsoft Academic Search

The diverse factors affecting the viscosity of a surfactant stabilized viscous crude oil-in-water emulsion for pipeline transportation were studied. The study discloses that the stability of the oil-in-water emulsion stabilized by a nonionic surfactant Nonyl Phenol Ethoxylate increases as the surfactant concentration increases with a subsequent decrease in the crude-oil–water interfacial tension (IFT). Increasing the oil content and the speed

Nehal S. Ahmed; Amal M. Nassar; Nael N. Zaki; Hussein Kh. Gharieb

1999-01-01

174

Influence of hydrophobic alkylated gold nanoparticles on the phase behavior of monolayers of DPPC and clinical lung surfactant.  

PubMed

The effect of hydrophobic alkylated gold nanoparticles (Au NPs) on the phase behavior and structure of Langmuir monolayers of dipalmitoylphosphatidylcholine (DPPC) and Survanta, a naturally derived commercial pulmonary surfactant that contains DPPC as the main lipid component and hydrophobic surfactant proteins SP-B and SP-C, has been investigated in connection with the potential implication of inorganic NPs in pulmonary surfactant dysfunction. Hexadecanethiolate-capped Au NPs (C(16)SAu NPs) with an average core diameter of 2 nm have been incorporated into DPPC monolayers in concentrations ranging from 0.1 to 0.5 mol %. Concentrations of up to 0.2 mol % in DPPC and 16 wt % in Survanta do not affect the monolayer phase behavior at 20 °C, as evidenced by surface pressure-area (?-A) and ellipsometric isotherms. The monolayer structure at the air/water interface was imaged as a function of the surface pressure by Brewster angle microscopy (BAM). In the liquid-expanded/liquid-condensed phase coexistence region of DPPC, the presence of 0.2 mol % C(16)SAu NPs causes the formation of many small, circular, condensed lipid domains, in contrast to the characteristic larger multilobes formed by pure lipid. Condensed domains of similar size and shape to those of DPPC with 0.2 mol % C(16)SAu NPs are formed by compressing Survanta, and these are not affected by the C(16)SAu NPs. Atomic force microscopy images of Langmuir-Schaefer-deposited films support the BAM observations and reveal, moreover, that at high surface pressures (i.e., 35 and 45 mN m(-1)) the C(16)SAu NPs form honeycomb-like aggregates around the polygonal condensed DPPC domains. In the Survanta monolayers, the C(16)SAu NPs were found to accumulate together with the proteins in the liquid-expanded phase around the circular condensed lipid domains. In conclusion, the presence of hydrophobic C(16)SAu NPs in amounts that do not influence the ?-A isotherm alters the nucleation, growth, and morphology of the condensed domains in monolayers of DPPC but not of those of Survanta. Systematic investigations of the effect of the interaction of chemically defined NPs with the lipid and protein components of lung surfactant on the physicochemical properties of surfactant films are pertinent to understanding how inhaled NPs impact pulmonary function. PMID:22118426

Tatur, Sabina; Badia, Antonella

2012-01-10

175

Effects of aqueous-phase acidity and salinity on isotonic swelling of W\\/O\\/W emulsion liquid membranes under agitation conditions  

Microsoft Academic Search

The effects of aqueous-phase acidity and salinity on the isotonic swelling behavior of water-in-oil-in-water (W\\/O\\/W) emulsion liquid membranes (ELMs) under agitation conditions was studied. A non-ionic surfactant (EMSORB 2500) was used to stabilize the membranes. The acidity of the aqueous phase was controlled by sulfuric acid and the salinity was controlled by sodium sulfate. The swelling of the ELMs was

Jun Yan; Rajinder Pal

2004-01-01

176

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

177

Effect of surfactant structure on the phase behavior of alkylxylenesulphonate\\/crude oil\\/brine systems  

Microsoft Academic Search

One of the major criteria applied in the design of surfactants for micellar flooding is their effectiveness in stabilizing a middle phase microemulsion under the conditions of the candidate reservoir. A study has been made of the performance in this respect of linear alkylxylenesulfonates (ENORDET LXS) with equivalent weights ranging from 345 to 472 with well-defined molecular structures. Among the

T. A. B. M. Bolsman; C. J. R. Daane

1983-01-01

178

The effect of the additive concentration in emulsions to the tribological behavior of a cold rolling tube under sliding contact  

Microsoft Academic Search

The industrial steel tube in the cold rolling processes under liquid lubrication was simulated in a recovered cutting machine to study the tribological performances of an emulsion with four different concentrations of an emulsifier. The test machine was equipped with a device to measure the electrical contact resistance (ECR) between the rubbing surfaces of a steel tube and a roller.

Un Chia Chen; Yu Shi Liu; Chong-Ching Chang; Jen Fin Lin

2002-01-01

179

The entrainment swelling of emulsion during lactic acid extraction by LSMs  

Microsoft Academic Search

Studies on the entrainment swelling of emulsion during batch extraction of lactic acid using a liquid surfactant membrane (LSM) system are reported. The concept of effective concentration of surfactant in membrane phase has been proposed, considering the high adsorption density of the surfactant at the droplet interfaces in the LSM system. The swelling caused by emulsification during the initial dispersion

Wang Zihao; Jiang Yuanli; Fu Jufu

1996-01-01

180

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

2011-06-01

181

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

182

Effect of Surfactant Structure on Phase Behavior of Alkylxylenesulfonate\\/ Crude-Oil\\/Brine Systems  

Microsoft Academic Search

One of the major criteria for designing surfactants for micellar flooding is their effectiveness in stabilizing a middle-phase microemulsion under the conditions of the candidate reservoir. The authors studied the performance of linear alkyl-o-xylenesulfonates (Enordet LXS) with equivalent weights ranging from 345 to 472 with well-defined molecular structures. They used information about a previously described quantitative relationship between the mole

T. A. B. M. Bolsman; G. J. R. Danne

1986-01-01

183

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

2012-06-26

184

Sorption/desorption behavior of oxytetracycline and sulfachloropyridazine in the soil water surfactant system.  

PubMed

Sorption/desorption of antibiotics, oxytetracycline (OTC), and sulfachloropyridazine (SCP) was investigated in the presence of a nonionic surfactant Brij35. Batch sorption experiments indicated that Freundlich equation fits sorption isotherms well for OTC. The sorption coefficients, KF, values were computed as 23.55 mL g(?1) in the absence of Brij35 and 25.46 mL g(?1) in the presence of Brij35 in the monomer form (below critical micelle concentration CMC, of 74 mg L(?1)). However, the KF values reduced to 12.76 mL g(?1) in the presence of Brij35 at 2.5 g L(?1). Therefore, irrigation with surfactant-rich water may increase the leaching potential of OTC. In the case of SCP, the KF value, in the absence of Brij35, was 19.95 mL g(?1). As a result of increasing the concentration of Brij35 to 0.25 g L(?1) (about 2.5 CMC), KF values first increased and reached a maximum value of 95.49 mL g(?1) and then reduced to 66.06 mL g(?1), at surfactant concentration of 5 g L(?1). Unlike OTC, the presence of surfactant in irrigation water is likely to decrease SCP leaching. In the case of OTC, hysteresis was found at Brij35 concentrations below CMC. However, OTC desorbed readily from soil (no hysteresis) at Brij35 concentrations above CMC. In the case of SCP, no hysteresis was found in the presence of the surfactant, both below and above CMC. Further, the obtained values of the efficiency coefficient (E), reveals that Brij35 had the potential to release more OTC from the soil (E?>?1) as compared to SCP (E?

ElSayed, Eman M; Prasher, Shiv O

2014-03-01

185

Raspberry-shaped composite microgel synthesis by seeded emulsion polymerization with hydrogel particles.  

PubMed

A series of raspberry-shaped composite microgels were synthesized by the seeded emulsion polymerization of styrene with hydrogel particles. Thermoresponsive microgels of poly(N-isopropylacrylamide) cross-linked with N,N'-methylenebis(acrylamide) acted as cores for the polymerization. During the surfactant-free polymerization, the core microgels shrank at 70 °C to provide thermoresponsive composite microgels, and the polystyrene particles attached to core microgels became bigger with increasing styrene concentration. Conversely, composite microgels synthesized with sodium dodecyl sulfate (SDS) ([SDS] > 6.5 mM) did not exhibit thermoresponsive deswelling behavior because polystyrene particles covered the core microgels. In particular, polystyrene particles formed composites on the microgel surface as well as inside the microgels when the SDS concentration exceeded a critical value for core microgel swelling at 70 °C. A mechanism is proposed based on these results for the seeded emulsion polymerization of water-immiscible monomers with microgels. PMID:24881767

Suzuki, Daisuke; Kobayashi, Chiaki

2014-06-24

186

Differences between the detonation behavior of emulsion explosives sensitized with glass or with polymeric micro-balloons  

NASA Astrophysics Data System (ADS)

The differences between the detonation behaviour of ammonium nitrate based emulsion explosives sensitized with polymeric and those sensitized with glass micro-balloons is presented and discussed. Expancel® are hollow polymeric micro-balloons that contain a hydrocarbon gas. The mean particle size of these particles is 30 ?m with a wall thickness of about 0.1 ?m. The detonation velocity and the failure diameter of the emulsion explosive sensitized with different amounts of these particles have been measured in cylindrical charges by optical fibers. The detonation velocity demonstrates non-linear behaviour in relation to density and reaches the maximum value for a density lower than that of the matrix. The detonation fails when the density approaches that of the matrix. The detonation in the emulsion explosives extinguishes itself at a porosity value that seems to be independent from the nature of the sensitizing agent. For low densities, the detonation velocity is almost independent of the charge diameter, and is close to the values predicted by BKW equation of state.

Mendes, R.; Ribeiro, J.; Plaksin, I.; Campos, J.; Tavares, B.

2014-05-01

187

Adsorption and Corrosion Inhibition Behavior of Polyethylene Glycol and Surfactants Additives on Mild Steel in H2SO4  

NASA Astrophysics Data System (ADS)

The adsorption and corrosion inhibition behaviors of polyethylene glycol (PEG) alone and in the presence of surfactants sodium dodecyl benzene sulfonate and cetyltrimethyl ammonium bromide on mild steel in 0.1 M H2SO4 in temperature range of 30-60 °C was investigated using weight loss method, solvent analysis of iron ions, scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), atomic force microscopy (AFM) and determination of kinetic/thermodynamic parameters. The inhibition efficiency (IE) of PEG increased with increasing concentration showing a maximum IE of 86.91% at 30 °C at 25 ppm but decreased with increasing temperature. Inhibiting action of PEG is synergistically enhanced on addition of small amount of surfactants. Surface morphology of the corroded mild steel specimen as evaluated by SEM, EDAX and AFM confirmed the existence of an adsorbed protective film on the mild steel surface. The calculated thermodynamic/kinetic parameters reveal that adsorption process is spontaneous and obey Langmuir adsorption isotherm.

Mobin, M.; Khan, M. A.

2014-01-01

188

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

189

Study to Determine the Technical and Economic Feasibility of Reclaiming Chemicals Used in Micellar Polymer and Low Tension Surfactant Flooding. Final Report.  

National Technical Information Service (NTIS)

Energy Resources Company has developed a technology for use with enhanced oil recovery to achieve emulsion breaking and surfactant recovery. By using ultrafiltration membranes, the Energy Resources Company process can dewater an oil-in-water type emulsion...

R. H. Stephens A. Himmelblau R. G. Donnelly

1978-01-01

190

Polyion-surfactant ion complex salts formed by a random anionic copolyacid at different molar ratios of cationic surfactant: phase behavior with water and n-alcohols.  

PubMed

The presence of acid groups with different pK(a) values in the anionic copolymer poly(4-styrene sulfonic acid-co-maleic acid), P(SS-Ma), allowed the preparation of complex salts with a variable fraction of anionic groups neutralized by cationic surfactant in the copolymer via controlled titration with hexadecyltrimethylammonium hydroxide, C(16)TAOH. Two new complex salts were selected for detailed phase studies, C(16)TA(2)P(SS-Ma) and C(16)TA(3)P(SS-Ma), where both had 100% charged styrene sulfonate groups, but the fraction of charged carboxylate groups on the polyion was 50% or 100%, respectively. These complex salts thus contained both hydrophobic (styrene sulfonate) and hydrophilic (carboxylate) charged groups, and the ratio between the two could be altered by titration. These features were found to have consequences for the phase behavior in water and in ternary mixtures with water and n-alcohols for the two complex salts, which differed compared to complex salts containing homo- or copolyions with only carboxylate or styrene sulfonate charged groups. For both complex salts, binary mixtures with water produced, in the dilute region, two isotropic phases in equilibrium, the bottom (concentrated) one displaying increasing viscosity with increasing concentration. For the complex salt C(16)TA(2)P(SS-Ma), there was evidence of micellar growth to form anisometric aggregates at high concentrations. For the C(16)TA(3)P(SS-Ma) complex salt, this was not observed, and the isotropic phase was followed by a narrow region of cubic phase. In both cases, concentrations above ca. 60 wt % produced a hexagonal phase. For ternary mixtures with n-alcohols, the general trend was that a short-chain alcohol such as n-butanol acted as a cosolvent dissolving the aggregates, whereas with n-decanol, a cosurfactant effect was observed, inducing the formation of lamellar phases. Visual inspection (also between crossed polarizers), small angle X-ray scattering (SAXS) and diffusion nuclear magnetic resonance (NMR) were used in these studies. PMID:22288901

Percebom, Ana Maria; Piculell, Lennart; Loh, Watson

2012-03-01

191

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

192

Synthesis of fluorosurfactants for emulsion-based biological applications.  

PubMed

Microemulsion represents an attractive platform for fundamental and applied biomedical research because the emulsified droplets can serve as millions of compartmentalized micrometer-sized reactors amenable to high-throughput screening or online monitoring. However, establishing stable emulsions with surfactants that are compatible with biological applications remains a significant challenge. Motivated by the lack of commercially available surfactants suitable for microemulsion-based biological assays, this study describes the facile synthesis of a biocompatible fluorosurfactant with nonionic tris(hydroxymethyl)methyl (Tris) polar head groups. We have further demonstrated compatibility of the developed surfactant with diverse emulsion-based applications, including DNA polymeric nanoparticle synthesis, enzymatic activity assay, and bacterial or mammalian cell culture, in the setup of both double- and multiphases of emulsions. PMID:24646088

Chiu, Ya-Ling; Chan, Hon Fai; Phua, Kyle K L; Zhang, Ying; Juul, Sissel; Knudsen, Birgitta R; Ho, Yi-Ping; Leong, Kam W

2014-04-22

193

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

2013-09-14

194

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

195

Evaluation of mixed surfactants for improved chemical flooding.  

National Technical Information Service (NTIS)

Phase behavior studies were conducted using combinations of a primary surfactant component and several ethoxylated surfactants. The objective of the study is to evaluate combinations of surfactants, anionic-nonionic and anionic-anionic mixtures, that woul...

F. M. Llave T. R. French P. B. Lorenz

1993-01-01

196

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

NASA Astrophysics Data System (ADS)

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, ?˜CR?(?CRR/?)?0.40 , which is independent of surfactant used, solution viscosity, and bubble volume fraction (varied between 92 and 98 %). Here ?CR is the dimensional shear stress, above which a bubble with radius R and surface tension ? would break in sheared foam. The value of the critical stress experimentally found by us ?˜CR?0.40 , is about two orders of magnitude lower than the critical stress for breakup of single bubbles in sheared Newtonian liquids, ?˜CR?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% ???95% to study drop breakup in concentrated emulsions. Qualitatively similar behavior was observed to that of foams, with the critical dimensionless stress for drop breakup being lower, ?˜CR?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.

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

2008-11-01

197

Synthesis of mesoporous hydrophobic silica microspheres through a modified sol–emulsion–gel process  

Microsoft Academic Search

Mesoporous silica microspheres were synthesised through a sol–emulsion–gel process using Span 80 as the surfactant in silica\\u000a sol\\/n-hexane water in oil emulsion system. Surface modification of the microspheres was done with trimethylchlorosilane to obtain\\u000a hydrophobic silica microspheres. Various parameters related to the synthesis of microspheres, including concentration of surfactant\\u000a and viscosities of sol were studied. The hydrophobicity (wettability), thermal stability,

S. Smitha; P. Shajesh; P. Mukundan; K. G. K. Warrier

2008-01-01

198

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

2013-08-20

199

Basic prerequisites for the formation of stable water/fuel emulsions  

SciTech Connect

Distinguishes types of water/fuel emulsions (WFE) used to introduce water into internal combustion engines (emulsions of water in hydrocarbons; emulsions of hydrocarbons in water; microemulsions), and 3 types of emulsion stability. Focuses on the formation of stable emulsions of water in fuel, as this type of emulsion, will apparently be the first to come into use. Suggests that for the stabilization of WFEs, it is advisable to use a combination of surfactants that will lower the water/hydrocarbon interfacial tension to 1 mN/m or less, with relatively low concentrations of surfactant. Recommends that the formulations should include emulsion stabilizers to prevent drop coalescence and substances to prevent flocculation. Points out that the choice of such surfactants will depend on the emulsion type and on the particular hydrocarbon phase. Notes that nonionic surfactants are the most frequently used, with petroleum sulfonates and water-souble polymers, either synthetic (such as block copolymers of ethylene and propylene oxides) or natural (dextrin), also used as stabilizers of WFEs.

Chistyakov, B.E.; Bedenko, V.G.

1982-11-01

200

Preparation and evaluation of w\\/o\\/w type emulsions containing vancomycin  

Microsoft Academic Search

The objective of this contribution is to summarize the preparation and application of water-in-oil-in-water type multiple emulsions (w\\/o\\/w emulsions) entrapping vancomycin (VCM). Formulations of the emulsions (the composition of an oily phase or the type and concentrations of surfactants) and emulsification methods (a stirring method and a membrane method) or conditions (rotation rates, pore sizes of membrane or operation pressures)

Hideaki Okochi; Masahiro Nakano

2000-01-01

201

Preparation of spherical SnO 2 particles by W\\/O type emulsion method  

Microsoft Academic Search

An attempt to prepare spherical particles was made using a W\\/O type emulsion as a reaction field. The effects of surfactant content, W\\/O ratio and stirring conditions for the preparation of emulsions, which determined the size of water drops in the emulsions, were investigated on the size and morphology of the obtained SnO2 particles. The size and morphology of the

H. Shiomi; C. Tanaka

2002-01-01

202

Monodispersed W\\/O emulsion prepared by hydrophilic ceramic membrane emulsification  

Microsoft Academic Search

Monodispersed W\\/O emulsions were prepared by an integrated ceramic membrane emulsification system. Kerosene was used as the continuous phase and water was used as the dispersed phase. By adding a cationic surfactant into the dispersed phase, the hydrophilic ceramic membrane can be directly used as the emulsification medium for the preparation of monodispersed W\\/O emulsions. Monodispersed W\\/O emulsion with a

Wenheng Jing; Jun Wu; Wanqin Jin; Weihong Xing; Nanping Xu

2006-01-01

203

Unusual behavior of the aqueous solutions of gemini bispyridinium surfactants: apparent and partial molar enthalpies of the dimethanesulfonates.  

PubMed

Apparent and partial molar enthalpies at 298 K of the aqueous solutions of cationic gemini surfactants 1,1'-didodecyl-2,2'-dimethylenebispyridinium dimethanesulfonate (12-Py(2)-2-(2)Py-12 MS); 1,1'-didodecyl-2,2'-trimethylenebispyridinium dimethanesulfonate (12-Py(2)-3-(2)Py-12 MS); 1,1'-didodecyl-2,2'-tetramethylenebispyridinium dimethanesulfonate (12-Py(2)-4-(2)Py-12 MS); 1,1'-didodecyl-2,2'-octamethylenebispyridinium dimethanesulfonate (12-Py(2)-8-(2)Py-12 MS); 1,1'-didodecyl-2,2'-dodecamethylenebispyridinium dimethanesulfonate (12-Py(2)-12-(2)Py-12 MS) were measured as a function of concentration and are here reported for the first time. They show a very peculiar behavior as a function of the spacer length, not allowing for the determination of a -CH 2- group contribution when this group is added to the spacer. The curve of the compound with a four-carbon-atom-long spacer lies between those of the compound with a spacer of 2 and 3 carbon atoms, instead of that below the latter, as expected. This surprising behavior, never found before in the literature and different from that found for the more popular m- s- m-type bisquaternary ammonium gemini surfactants, could be explained by a conformation change of the molecule, caused by stacking interactions between the two pyridinium rings, mediated by the counterion and appearing at an optimum length of the spacer. The hypothesis is also supported by the data obtained from the surface tension vs log c curves, showing that A min, the minimum area taken at the air-water interface by the molecule, is significantly lower for 12-Py(2)-4-(2)Py-12 MS than that of the other compounds of the same homologous series, and that the same compound has a greater tendency to form micelles instead of adsorbing at the air/water interface. The evaluation of the micellization enthalpies, by means of a pseudophase transition model, agrees with the exposed trends. These results confirm the great crop of information that can be derived from the study of the solution thermodynamics of aggregate systems and in particular from the curves of apparent and molar enthalpies vs concentration. PMID:18767790

Fisicaro, Emilia; Compari, Carlotta; Biemmi, Mariano; Duce, Elenia; Peroni, Monica; Barbero, Nadia; Viscardi, Guido; Quagliotto, Pierluigi

2008-10-01

204

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. ...

205

Texture optimization of water-in-oil emulsions.  

PubMed

The aim of this research is to demonstrate the effect of variations in certain parameters of the oily phase (OP) in water-in-oil (W/O) emulsions on rheological and texture properties of finished products. The formulated emulsions were selected according to an optimal experimental procedure. The applied variations were nature of the OP, its volume fraction, the hydrophilic-lipophilic balance (HLB) value, and the surfactant proportion. Results are presented for the followed tests carried out on the emulsions: texture analysis, rheology, and particle size analysis. The oils used in the study were sweet almond oil, liquid paraffin, maize oil, cyclomethicone, dimethicone, and wheat germ oil. The resulting data demonstrate a notable influence of the volume fraction oil on hardness, viscosity, adhesiveness, and cohesiveness of W/O emulsions. Emulsion hardness and viscosity increased as the OP percentage increased; this effect being even more pronounced for the vegetable oils. In contrast, emulsion adhesiveness and cohesiveness decreased as the volume fraction oil increased. The HLB value of the surfactant mixture of the emulsion also influenced hardness, adhesiveness, and elasticity, increasing or decreasing as HLB value did. PMID:15202571

Lemaitre-Aghazarian, V; Piccerelle, P; Reynier, J P; Joachim, J; Phan-Tan-Luu, R; Sergent, M

2004-01-01

206

Seismic properties of a Venezuelan heavy oil in water emulsion  

SciTech Connect

Several procedures for the production of low-viscosity, surfactant-stabilized, easy-transportable dispersions of heavy crude oil in water-briefly, oil in water (or o/w) emulsions - have been recently patented. Some of them propose to form the o/w emulsion in the reservoir, after the injection of a mixture of water and surfactants, increasing significantly the per well daily production. Progression of the o/w emulsion front, through the reservoir to the production wells, can be monitored in seismic planar slices with successive 3D seismic surveys (413 seismic), if enough contrast exists between the seismic velocity value of the o/w emulsion and the one of the oil in place. To facilitate the analysis of the contrast, this study presents high frequency acoustic velocity measurements performed in the laboratory. The experimental setup includes two reflectors and an ultrasonic transducer with double burst train emission. The estimated velocity precision is 0.02%. The measured samples are: a Venezuelan heavy o/w emulsion, a mixture of the same heavy oil and gasoil and a saturated sandstone core containing the o/w emulsion. Additionally, seismic velocities of the actual pore fluids - live oil and five o/w emulsion - and saturated sandstone are calculated using the above laboratory measurements, Wood`s equation, and Gassman`s and Biot`s models.

Maldonado, F.; Liu, Y.; Mavko, G.; Mukerji, T. [Stanford Univ., CA (United States)

1996-08-01

207

Light and neutron scattering study of PEG-oleate and its use in emulsion polymerization.  

PubMed

Steric stabilization of colloids forms a robust mechanism to obtain colloids that are stable in a variety of environments, and that can be used to study the phase behavior of hard or soft spheres. We report the synthesis of sterically stabilized colloids in an aqueous environment using readily dissolvable surfactants, with an unsaturated hydrophobic tail. We synthesized a new surfactant by esterification of a poly(ethylene glycol) (PEG) chain of 4.1 kg/mol with oleic acid, called PEG4OA. The micellization of PEG4OA was characterized by light and neutron scattering, which yielded values for the aggregation number and the overall size that are in excellent agreement with a comparable surfactant with a saturated octadecane chain, Brij 700. We successfully used PEG4OA in the emulsion polymerization of polystyrene colloids. In comparison with the smaller surfactant Tween 80, PEG4OA yielded smaller colloids with radii around 50 nm, and the addition of 1-dodecanethiol reduced the formation of aggregates during the synthesis. A contrast variation study with small angle neutron scattering (SANS) showed that a dense PEG layer was grafted to the colloid surface. PMID:22708656

van Gruijthuijsen, Kitty; Rufier, Chantal; Phou, Ty; Obiols-Rabasa, Marc; Stradner, Anna

2012-07-17

208

Induction of amphiphilicity in polymer@silica particles: ceramic surfactants.  

PubMed

It is shown that, in general, when submicrometer hybrid particles of polymer@silica are subjected to thermal treatment, phase-separated hydrophobicity emerges at particles surface; and that the triggering of hydrophobicity results in particles which show amphiphilic behavior, arranging themselves at water interfaces and stabilizing W/O and O/W emulsions. Many polymer@silica particles show this behavior, and the entrapped polymers include polyethylene Engage, poly(dimethylsiloxane), poly-l-lactic acid, poly(ethylene-block-ethyleneglycol), poly(styrene-co-allyl-achohol), and poly(dimethylesiloxane-block-ethyleneoxide-co-propyleneoxide). The concept is attractive because, by doping the particles with functional molecules, one can get various surfactants from the same treated particle; this is demonstrated with fluorescent probes. It is proposed that the amphiphilic activity is due to Janus heterogeneous distribution of the hydrophobic moieties on the surface. PMID:23339687

Fuchs, Ido; Avnir, David

2013-03-01

209

Surfactants Used in Food Industry: A Review  

Microsoft Academic Search

The understanding of the formation, structures, and properties of emulsions is essential to the creation and stabilization of structures in food. The increasing use of surfactants, the identification of compounds with low toxicity and good surface activity properties is of great interest. The relevance of the major end points specified in the Organisation for Economic Co-operation and Development (OECD) guidelines

Iva Kralova; Johan Sjöblom

2009-01-01

210

Electrochemical behavior of glassy carbon electrodes modified by multi-walled carbon nanotube\\/surfactant films in a buffer solution and an ionic liquid  

Microsoft Academic Search

The electrochemical behavior of glassy carbon (GC) electrodes coated with multi-walled carbon nanotube (MWCNT)\\/surfactant films was studied in an ionic liquid and a phosphate buffer solution (pH=6.86), using cyclic voltammetry. The dispersion of MWCNTs in different media was investigated by scanning and transmission electron microscopy. Cast films of MWCNT\\/zwitterionic dodecyldimethylamine oxide on a GC electrode show a typical redox couple

Yi Li; Xingwang Shi; Jingcheng Hao

2006-01-01

211

Sorption behavior of nonylphenol on marine sediments: Effect of temperature, medium, sediment organic carbon and surfactant  

Microsoft Academic Search

The sorption behavior of nonylphenol (NP, a toxic endocrine disruptor) on marine sediments was studied in detail through a series of kinetic and thermodynamic sorption experiments. The results showed that the sorption reaction of NP on marine sediments reached equilibrium in 1.5h and that it accorded well with the non-linear Ho-McKay pseudo-second-order model. The sorption isotherms of NP on H2O-treated

Gui-Peng Yang; Hai-Yan Ding; Xiao-Yan Cao; Qiong-Yao Ding

2011-01-01

212

Study on removal of cadmium from wastewater by emulsion liquid membrane.  

PubMed

Removal of cadmium from wastewater using emulsion liquid membrane (ELM) is studied in the present study. A polyamine-type surfactant was used for stabilizing the emulsion phase. Tri-iso-octyl amine (TIOA) has been used as a carrier for transferring of cadmium through the membrane. The results show good performance in the separation process. To determine the optimum operation conditions, the effect of several parameters such as surfactant concentration, carrier concentration, pH of external and internal phases, oil to internal phase volume ratio, emulsion to external phase volume ratio, solvent type, solute concentration, presence of iodide and chloride in external phase, and mixing conditions have been investigated. PMID:19036507

Mortaheb, Hamid R; Kosuge, Hitoshi; Mokhtarani, Babak; Amini, Mohammad H; Banihashemi, Hamid R

2009-06-15

213

Hexagonal phase based gel-emulsion (O/H1 gel-emulsion): formation and rheology.  

PubMed

The formation, stability, and rheological behavior of a hexagonal phase based gel-emulsion (O/H1 gel-emulsion) have been studied in water/C12EO8/hydrocarbon oil systems. A partial phase behavior study indicates that the oil nature has no effect on the phase sequences in the ternary phase diagram of water/C12EO8/oil systems but the domain size of the phases or the oil solubilization capacity considerably changes with oil nature. Excess oil is in equilibrium with the hexagonal phase (H1) in the ternary phase diagram in the H1+O region. The O/H1 gel-emulsion was prepared (formation) and kept at 25 degrees C to check stability. It has been found that the formation and stability of the O/H1 gel-emulsion depends on the oil nature. After 2 min observation (formation), the results show that short chain linear hydrocarbon oils (heptane, octane) are more apt to form a O/H1 gel-emulsion compared to long chain linear hydrocarbon oils (tetradecane, hexadecane), though the stability is not good enough in either system, that is, oil separates within 24 h. Nevertheless, the formation and stability of the O/H1 gel-emulsion is appreciably increased in squalane and liquid paraffin. It is surmised that the high transition temperature of the H1+O phase and the presence of a bicontinuous cubic phase (V1) might hamper the formation of a gel-emulsion. It has been pointed out that the solubilization of oil in the H1 phase could be related to emulsion stability. On the other hand, the oil nature has little or no effect on the formation and stability of a cubic phase based gel-emulsion (O/I1 gel-emulsion). From rheological measurements, it has found that the rheogram of the O/H1 gel-emulsion indicates gel-type structure and shows shear thinning behavior similar to the case of the O/I1 gel-emulsion. Rheological data infer that the O/I1 gel-emulsion is more viscous than the O/H1 gel-emulsion at room temperature but the O/H1 gel-emulsion shows consistency at elevated temperature. PMID:18847293

Alam, Mohammad Mydul; Aramaki, Kenji

2008-11-01

214

The effect of the rigidity of perfluoropolyether surfactant on its behavior at the water/supercritical carbon dioxide interface.  

PubMed

We performed a series of molecular dynamics simulations to study the PFPE (perfluoropolyether) and PE (polyether) surfactant monolayers at the water/supercritical carbon dioxide interface. Molecular differences between fluorocarbon surfactant PFPE and its hydrocarbon analogue PE were analyzed. We observed that values of intramolecular bonded interaction parameters which are related to chain rigidity determine the monolayer surface pressure. We show that "good" and "bad" properties of PFPE/PE surfactants are connected to conformational entropy. These results are consistent with our previous micellar simulations. PMID:16853822

Lu, Lanyuan; Berkowitz, Max L

2005-11-24

215

Development of an ab initio emulsion atom transfer radical polymerization: from microemulsion to emulsion.  

PubMed

Atom transfer radical polymerization (ATRP) has been successfully extended to an ab initio emulsion system using a "two-step" procedure, in which the final emulsion polymerization system was formed by adding monomer to an ongoing microemulsion ATRP. The newly developed AGET (activators generated by electron transfer) initiation technique was employed in the first stage of this ab initio ATRP. It allows using oxidatively stable Cu(II) species that is reduced in situ by ascorbic acid. The surfactant concentration in the final emulsion system was efficiently decreased to approximately 2 wt % (approximately 10 wt % vs monomer) by decreasing the catalyst concentration and changing the ratio of the monomer added at the microemulsion stage to the monomer added during the second stage. This two-step procedure avoids the necessity of transporting catalysts through the aqueous media during polymerization, resulting in a controlled emulsion polymerization, as evidenced by a linear first-order kinetic plot and formation of a polymer with a relatively narrow molecular weight distribution (Mw/Mn = 1.2-1.4). The polymerization typically reached 70-90% monomer conversion in 5-6 h. The resulting polymer had high chain-end functionality and was successfully chain extended to form in situ block copolymers by adding the second monomer to an ongoing emulsion polymerization. The stable latex from the ab initio emulsion ATRP had a particle size approximately 120 +/- 10 nm. PMID:16895419

Min, Ke; Gao, Haifeng; Matyjaszewski, Krzysztof

2006-08-16

216

Oral absorption of a valsartan-loaded spray-dried emulsion based on hydroxypropylmethyl cellulose.  

PubMed

The aim of this study was to develop a novel valsartan-loaded spray-dried emulsion based on hydroxypropylmethyl cellulose (HPMC) with enhanced oral absorption. The valsartan-loaded redispersible dry emulsion was prepared by using a high-pressure homogenization and spray-drying process with water, Capryol 90, HPMC, and different surfactants, based on the results of the solubility study. The spray-dried emulsions formed small and homogeneous emulsions with a mean droplet emulsion size ranging from 133.5 to 152.5nm at the dispersion state in water. The valsartan-loaded redispersible dry emulsion with HPMC/poloxamer 407 showed enhanced pH-independent valsartan release, resulting in a dramatically enhanced oral bioavailability of valsartan compared to the raw material and commercial product. Therefore, a formulation strategy using the redispersible dry emulsion with HPMC/poloxamer 407 is very effective for the development of a new dosage form containing valsartan. PMID:24879921

Baek, In-Hwan; Kim, Jung-Soo; Ha, Eun-Sol; Choo, Gwang-Ho; Cho, Wonkyung; Hwang, Sung-Joo; Kim, Min-Soo

2014-08-01

217

Coalescence stability of emulsions containing globular milk proteins.  

PubMed

This review summarizes a large set of related experimental results about protein adsorption and drop coalescence in emulsions, stabilized by globular milk proteins, beta-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 observed in all systems studied. In the surfactant-rich regime, d32 does not depend on emulsifier concentration and is determined mainly by the interfacial tension and the power dissipation density in the emulsification chamber, epsilon. In the surfactant-poor regime and suppressed electrostatic repulsion, d32 is a linear function of the inverse initial emulsifier concentration, 1/C(INI), which allows one to determine the threshold emulsifier adsorption needed to stabilize the oil drops during emulsification, Gamma* (the latter depends neither on oil volume fraction nor on epsilon). Second, we study how the BLG adsorption on drop surface changes while varying the protein and electrolyte concentrations, and pH of the aqueous phase. At low electrolyte concentrations, the protein adsorbs in a monolayer. If the pH is away from the isoelectric point (IEP), the electrostatic repulsion keeps the adsorbed BLG molecules separated from each other, which precludes the formation of strong intermolecular bonds during shelf-storage as well as after heating of the emulsion. At higher electrolyte concentration, the adsorption Gamma increases, as a result of suppressed electrostatic repulsion between the protein molecules; monolayer or multilayer is formed, depending on protein concentration and pH. The adsorption passes through a maximum (around the protein IEP) as a function of pH. Third, the effect of various factors on the coalescence stability of "fresh" emulsions (up to several hours after preparation) was studied. Important conclusion from this part of the study is the establishment of three different cases of emulsion stabilization: (1) electrostatically-stabilized emulsions with monolayer adsorption, whose stability is described by the DLVO theory; (2) emulsions stabilized by steric repulsion, created by protein adsorption multilayers - a simple model was adapted to describe the stability of these emulsions; and (3) emulsions stabilized by steric repulsion, created by adsorption monolayers. Fourth, we studied how the emulsion stability changes with storage time and after heating. At high electrolyte concentrations, we find a significant decrease of the coalescence stability of BLG-emulsions after one day of shelf-storage (aging effect). The results suggest that aging is related to conformational changes in the protein adsorption layer, which lead to formation of extensive lateral non-covalent bonds (H-bonds and hydrophobic interactions) between the adsorbed molecules. The heating of BLG emulsions at high electrolyte concentration leads to strong increase of emulsion stability and to disappearance of the aging effect, which is explained by the formation of disulfide bonds between the adsorbed molecules. The emulsion heating at low electrolyte concentration does not affect emulsion stability - this result is explained with the electrostatic repulsion between the adsorbed molecules, which keeps them separated so that no intermolecular disulfide bonds are formed. Parallel experiments with WPC-stabilized emulsions show that these emulsions are less sensitive to variations of pH and thermal treatment; no aging effect is detected up to 30 days of storage. The observed differences between BLG and WPC are explained with the different procedures of preparation of these protein samples (freeze-drying and thermally enhanced spray-drying, respectively). Our data for emulsion coalescence stability are compared with literature results about the flocculation stability of BLG emulsions, and the observed similarities/differences are explained by considering the structure of the protein a

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

2006-11-16

218

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

219

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

220

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

221

A comparative behavior of photophysical properties of Pluronic F127 and Triton X-100 with conventional zwitterionic and anionic surfactants  

Microsoft Academic Search

The mixed micellar properties of a triblock copolymer, Pluronic F127, (EO)97(PO)69(EO)97 and a nonionic surfactant, Triton X-100 (TX-100), in aqueous solution with conventional zwitterionic (alkyldimethylammoniopropane sulfonates) and anionic (sodium dodecylsulfate, SDS, and dodecylbenzene sulfonate, SDBS) surfactants were investigated with the help of fluorescence measurements at 25°C. From the variation of I1\\/I3 intensity ratio of pyrene fluorescence, the critical micelle concentration

Mandeep Singh Bakshi; Navjot Kaur; Rakesh Kumar Mahajan

2006-01-01

222

Flow of Super-Concentrated Emulsions  

NASA Astrophysics Data System (ADS)

Super concentrated emulsions, e.g., emulsion explosives, are two-phase systems consisting of aqueous droplets dispersed in an oil phase. The concentration of the disperse phase is 92-96 w.%, liquid droplets, containing a supersaturated aqueous solution of inorganic oxidizer salts. The flow of such emulsions is determined by their Theological properties as well as the time-dependent processes of ``aging'' which take place due to the thermodynamic instability of these emulsions. This work presents the results of experimental studies of the main effects that accompany the flow of such materials: non-Newtonian flow behavior, rheopexy which manifests as a slow increase of viscosity in the low shear rate domain, linear viscoelastic behavior, and the transition of elastic modulus to non-linearity at high amplitudes of deformation. The emulsions under study are non-Newtonian liquids. Experiments with the shear rate sweep demonstrate that the upward and downward branches of the flow curves coincide above some specific shear rate value. The upward experiments show the existence of a Newtonian section of the flow curve in the low-shear-rate domain, while the effect of yielding is observed on the downward curve. The wall slip in the flow of the emulsions under study is negligible. The elastic modulus is constant over a wide frequency range. Hence, viscoelastic relaxation processes might be expected at characteristic times of either >>100s or <0.01s. Strong non-linear behavior was observed in high amplitude experiments. The elastic modules (measured in oscillating testing and in elastic recovery) as well as the yield stress are proportional to D-2, while the Newtonian viscosity is proportional to D-1. Concentration dependence of rheological parameters is also discussed. The possible mechanism of emulsion flow is proposed. Aging leads to enhancement of the solid-like properties of emulsions, which can be treated as an ``emulsion-to-suspension transition''. However, this transition is incomplete because dispersions retain an ability to flow at stresses exceeding the yield stress value. It is shown that the aging of emulsions is caused by the slow crystallization of a supercooled salt solution without any noticeable coalescence effect. The evolution of mechanical properties of emulsions is correlated with the kinetics of structural changes during aging. The problem of transport characteristics of such emulsions is also discussed. It is shown that the choice of the flow curve fitting equation is not crucial for pipe flow design. The result can be used for practical applications in designing pipe transportation systems.

Masalova, Irina; Malkin, Alexander Ya.

2006-05-01

223

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

224

Relaxation Spectra and Viscoelastic Behavior of a Model Hydrophobically Modified Alkali-Soluble Emulsion (HASE) Polymer in Salt/SDS Solutions.  

PubMed

The viscoelastic behavior of a semidilute hydrophobically modified alkali-soluble emulsion (HASE)-C20 polymer in NaCl and NaCl/SDS (sodium dodecyl sulfate) solutions was determined using a Rheometric fluids rheometer and the data were converted to relaxation spectra. The dynamic moduli can be fitted with a multiple modes Maxwell model. In the presence of increasing amounts of NaCl, the moduli decrease, where G', decreases more rapidly than G". However, in the presence of SDS and 0.4 M NaCl, the dynamic moduli increase to a maximum at a critical concentration and decrease thereafter. The relaxation spectra suggest that the structure of the polymer network is complex and it contains two to six relaxation times, depending on the NaCl or SDS/0.4 M NaCl concentrations. With increasing NaCl concentrations, the fastest peak shifts to longer times while the slowest peak decreases. This corresponds to the destruction of the network as the polymer backbone collapses to form clusters with a larger aggregation number. For HASE in SDS/0.4 M NaCl solutions, the lifetime of both the hydrophobic junction (fastest peak) and network relaxation (slowest peak) shift to longer times, which suggests the strengthening of active junctions by bound SDS molecules. However, beyond a critical SDS concentration, the relaxation time of the polymer and hydrophobic junction decreases to an asymptotic value. Copyright 2000 Academic Press. PMID:11082247

Tan; Tam; Jenkins

2000-11-01

225

Recent Emulsion Technologies  

SciTech Connect

Emulsion technologies are very much developed in the last decade and still developing in both the emulsion gel and the data taking. Emulsion detectors are suitable for the neutrino experiments because they can distinguish all 3 flavors of neutrino. The OPERA experiment, a recent pillar in the emulsion experiments aiming at the first observation of the neutrino oscillation in CNGS beam in appearance mode, is running, showing the good capability to separate 3 flavor neutrino interactions. In this poster, the recent developments and prospects of the emulsions for the next generation experiments are reported.

Ariga, A. [A. Einstein Center for Fundamental Physics, LHEP, University of Bern, Sidlerstrasse 5, 3012 Bern (Switzerland)

2011-10-06

226

Aggregate and emulsion properties of enzymatically-modified octenylsuccinylated waxy starches.  

PubMed

Sorghum and maize waxy starches were hydrophobically modified with octenylsuccinic anhydride (OSA) and treated with enzymes before being used to emulsify ?-carotene (beta,beta-carotene) and oil in water. Enzyme treatment with ?-amylase resulted in emulsions that were broken (separated) earlier and suffered increased degradation of ?-carotene, whereas treatment with pullulanase had little effect on emulsions. Combinations of surfactants with high and low hydrodynamic volume (Vh) indicated that there is a relationship between Vh and emulsion stability. Degree of branching (DB) had little direct influence on emulsions, though surfactants with the highest DB were poor emulsifiers due to their reduced molecular size. Results indicate that Vh and branch length (including linear components) are the primary influences on octenylsuccinylated starches forming stable emulsions, due to the increased steric hindrance from short amphiphilic branches, consistent with current understanding of electrosteric stabilization. The success of OSA-modified sorghum starch points to possible new products of interest in arid climates. PMID:25037432

Sweedman, Michael C; Schäfer, Christian; Gilbert, Robert G

2014-10-13

227

Sorption behavior of nonylphenol on marine sediments: effect of temperature, medium, sediment organic carbon and surfactant.  

PubMed

The sorption behavior of nonylphenol (NP, a toxic endocrine disruptor) on marine sediments was studied in detail through a series of kinetic and thermodynamic sorption experiments. The results showed that the sorption reaction of NP on marine sediments reached equilibrium in 1.5 h and that it accorded well with the non-linear Ho-McKay pseudo-second-order model. The sorption isotherms of NP on H2O-treated sediments could be well described by the Linear isotherm model, while the sorption isotherm on H2O2-treated sediments could be well fitted with the Freundlich isotherm model. A positive correlation was found between the distribution coefficient (Kd) and the sediment organic carbon contents. The medium salinity showed a positive relation with the Kd and a negative relation with the dissolved organic carbon (DOC). Hexadecyl trimethyl ammonium bromide (CTAB) enhanced the sorption amount of NP the most, while sodium dodecylbenzenesulfonate (SDBS) enhanced it the least. The sorption reaction of NP on marine sediments was a spontaneous, physical, exothermic and entropy-decreasing process. PMID:21945014

Yang, Gui-Peng; Ding, Hai-Yan; Cao, Xiao-Yan; Ding, Qiong-Yao

2011-11-01

228

Synthesis of amphipathic block copolymers based on polyisobutylene and polyoxyethylene and their application in emulsion polymerization  

SciTech Connect

Polymer colloids stabilized by polymeric surfactants are of great interest both commercially and academically. It has been found that these materials enhance latex stabilization in a number of applications. The polymeric surfactants are amphipathic block and graft copolymers containing both hydrophilic and hydrophobic moieties. The current study involved the synthesis of a series of amphipathic triblock copolymers, polyisobutylene-block-polyoxyethylene-block-polyisobutylene (PIB-b-POE-b-PIB), for use in the emulsion polymerization of styrene (STY), methyl methacrylate (MMA), and vinyl acetate (VAc). The stabilizing effectiveness of these triblock copolymers was studied as a function of their blocklength. When the molecular weight of the POE center block was changed from M{sub n} = 2,000 to 20,000 g/mole, stable lattices were obtained in emulsion polymerization with MMA, STY, and VAc as the monomers. In all cases, the polymerization rates remained constant, while the number of particles/volume decreased with increasing POE chain length. When the molecular weight of the PIB end blocks was changed from M{sub n} = 400 to 2,600 g/mole keeping the molecular weight of the POE center block constant at M{sub n} = 20,000 g/mole, the poly(methyl methacrylate) and poly(vinyl acetate) lattices exhibited similar behavior, i.e., the number of particles and particle sizes remained the same, but the rate of polymerization reached a maximum at 87 wt% POE content. In the case of poly(styrene) both the rate of polymerization and the number of particles remained constant. The emulsion polymerization of other monomers such as butadiene, acrylonitrile, methyl acrylate, ethyl acrylate, and butyl acrylate was carried out by using one triblock copolymer, i.e., PIB(400)-b-POE (8,000)-b-PIB-(400). Stable lattices were also formed in all cases.

Sar, B.

1992-12-31

229

Novel phase behavior in three-component oil-water-surfactant systems. A truncated isotropic channel in the oil-rich regime  

SciTech Connect

The phase behavior of three-component systems of the type water + hydrocarbon + poly(oxyethylene) alkyl ether (C{sub 8}E{sub 4} and C{sub 10}E{sub 5}) has been studied at temperatures below the phase inversion. A narrow one-phase region was found in the oil-rich corner, which intrudes into the central miscibility gap between water and oil. At low temperatures the molar ratio of water and surfactant in this phase corresponds to two water molecules per oxyethylene group of the surfactant, and thus this phase may represent a hydrate strongly swollen with oil. As the temperature is raised, this region of one-phase stability becomes separated from the main one-phase region at higher surfactant concentrations and shrinks to a point at which this phase decomposes into two other liquid phases at a temperature T{sub max}. Below this temperature the one-phase region is connected with two narrow three-phase regions, one of which disappears at a lower critical end point while the other extends to much lower temperatures. Measurements of the densities, viscosities, and interfacial tensions at three-phase coexistence are also presented and are consistent with the proposed phase diagram.

Findenegg, G.H.; Hirtz, A.; Rasch, R.; Sowa, F. (Ruhr-Universitaet Bochum (Germany, F.R.))

1989-06-01

230

Optimization of process parameters for the extraction of chromium (VI) by emulsion liquid membrane using response surface methodology  

Microsoft Academic Search

The emulsion liquid membrane technique was used for the extraction of hexavalent chromium ions from aqueous solution of waste sodium dichromate recovered from the pharmaceutical industry wastewater. The liquid membrane used was composed of kerosene oil as the solvent, Span-80 as the surfactant and potassium hydroxide as internal reagent. Trioctyl amine and Aliquat-336 were used as carriers. The emulsion stability

M. Rajasimman; R. Sangeetha

2009-01-01

231

PREPARATION OF W\\/O\\/W EMULSIONS IN AN EDIBLE FORM ON THE BASIS OF PHASE INVERSION TECHNIQUE  

Microsoft Academic Search

An attempt was made to provide a basic composition and simple technique for preparing the W\\/O\\/W emulsions in an edible form in a view to possible food applications of this type of emulsions. It has been found that TGCR (tetraglyceryl condensed ricinoleate), which is one of the hydrophobic food surfactants, plays a relevant role in developing water\\/olive oil\\/water emulsions due

S. Matsumoto; Y. Koh; A. Michiure

1985-01-01

232

Production of W\\/O\\/W emulsions and S\\/O\\/W pectin microcapsules by microchannel emulsification  

Microsoft Academic Search

Water in oil in water (W\\/O\\/W) emulsions were produced by microchannel (MC) emulsification using water in oil (W\\/O) emulsions prepared by homogenization as feed emulsions. Polyoxyethylene sorbitan monolaurate (Tween 20) was used in the external water phase to stabilize oil droplets containing water droplets. Sorbitan monolaurate (Span 20), sorbitan monooleate (Span 80) and tetraglycerol polyricinoleate (TGPR) were tested as surfactants

Takahiro Kawakatsu; Gun Trägårdh; Christian Trägårdh

2001-01-01

233

Controlling phospholipid self-assembly and film properties using highly fluorinated components--fluorinated monolayers, vesicles, emulsions and microbubbles.  

PubMed

Use of fluorinated components instead or along with standard phospholipids in film, vesicle, bubble and emulsion engineering, can cause drastic modifications of the formation processes, structure and dynamics, and functional behavior of these systems. Perfluoroalkyl chains provide a powerful driving force for self-assembly and ordering. They allow, for example, obtainment of thermally stable vesicles from single-chain phosphocholine derivatives, tubules from non-chiral amphiphiles, faceted vesicles with fluid bilayer membranes, exceptionally stable and narrowly dispersed emulsions and microbubbles. Contact of a monolayer of DPPC with a fluorocarbon gas modifies the monolayer's phase behavior, suppressing the liquid expanded/liquid condensed transition. Phospholipid absorption kinetics at an air/water interface can be substantially accelerated, and the equilibrium interfacial tension reduced by exposure to a fluorocarbon gas. Perfluoroalkyl chains induce nanocompartmentation in films and membranes, allowing, for example, polymerization within vesicular membranes. Vesicles involving highly fluorinated components generally exhibit stability, permeability, fusion and recognition characteristics, different from those of their hydrogenated analogues. Drastic stabilization can be gained for phospholipid-coated emulsions through a co-surfactant effect of (perfluoroalkyl)alkyl diblocks. Stable, size-controlled, narrowly dispersed populations of microbubbles have been obtained using fluorinated wall and/or internal gas components, allowing progress in the understanding of microbubble physics, and open new application perspectives. PMID:21816205

Krafft, Marie Pierre

2012-01-01

234

Surfactant effect on the conductivity behavior of CsH 2PO 4: Characterization by electrochemical impedance spectroscopy  

NASA Astrophysics Data System (ADS)

Cesium dihydrogen phosphate (CDP) nanoparticles were synthesized using the surfactants cetyltrimethyl ammonium bromide (CTAB), polyoxyethylene-polyoxypropylene (F-68) and (F-68:CTAB) with molar ratio 0.06. The samples conductivity such as CDP CTAB, CDP F-68 and CDP (F-68:CTAB)0.06 was studied by impedance spectroscopy in the frequency range 0.01 Hz to 1 MHz. The Nyquist plots were drawn at different temperatures of 210, 230 and 260 °C, which are defined below transition, phase transition and above transition, respectively. The measured conductivities obey the Arrhenius relation. The influence of surfactants on conductivity are more significant at higher temperature due to grain boundary. The conductivity of CDP CTAB increased slightly with increasing temperature to 260 °C, whereas the conductivity of other samples decreased with increasing temperature over 230 °C. The results indicated that the conductivities increase in the order of CDP CTAB>CDP (F-68:CTAB)0.06>CDP F-68. These are in accordance to the ion exchange capacities of the samples that the surfactant shows a direct influence on the samples proton mobility. It is found that the conductivity of CsH 2PO 4 is influenced by surfactant type.

Hosseini, S.; Homaiee, M.; Mohamad, A. B.; Malekbala, M. R.; Khadum, A. A. H.

2011-04-01

235

Solubilization in monodisperse emulsions  

Microsoft Academic Search

The kinetics of oil solubilization into micelles from nearly monodisperse alkane-in-water emulsion droplets was investigated. Emulsions containing either hexadecane or tetradecane oils were fractionated to be narrowly distributed, using a method developed by Bibette [J. Bibette, J. Colloid Interface Sci. 147 (1991) 474]. These monodisperse emulsions were mixed with SDS or Tween 20 aqueous micellar solutions of various concentrations. Time-dependent

Suwimon Ariyaprakai; Stephanie R. Dungan

2007-01-01

236

Enhanced oil recovery through in-situ generated surfactants augmented by chemical injection  

SciTech Connect

Experimental and theoretical studies were conducted to advance understanding and predictability in the successful application of the combined surfactant-enhanced alkaline flooding for tertiary oil recovery. An experimental investigation of the buffered surfactant-enhanced alkaline flooding system chemistry was undertaken to determine the influence of the various species present on interfacial tension and phase behavior. The minimum in interfacial tension and the region of spontaneous emulsification correspond to a particular pH range, so that by buffering the aqueous pH against changes in alkali concentration, low interfacial tension can be maintained when the amount of alkali decreases due to the influence of external factors, such as divalent ions, acids, rock consumption, and dispersion. Reflected light micro-interferometry study was conducted to observe stratification in thin liquid films (associated with emulsion and foam systems) formed from micellar solutions of nonionic surfactants, such as ethoxylated alcohols. We show in the case of micellar solutions of nonionic surfactants that the stratification which results in the enhanced stability of films (and therefore the colloidal dispersion) is very sensitive to temperature. A new microwave interference dielectrometer was developed for characterizing oil-in-water and water-in-oil macroemulsions. The apparatus is readily applicable to either on-line or laboratory measurements. The dielectric properties of macroemulsions in the microwave frequency region were analyzed using interaction potential models and effective medium theories. 151 refs., 60 figs., 4 tabs.

Wasan, D.T.

1990-08-01

237

Preparation of fine W\\/O\\/W emulsion through membrane filtration of coarse W\\/O\\/W emulsion and disappearance of the inclusion of outer phase solution  

Microsoft Academic Search

A water-in-oil-in-water (W\\/O\\/W) emulsion was prepared as a carrier system for the daily uptake of a bioactive compound using decaglycerol monolaurate and hexaglyceryl condensed ricinolate as hydrophilic and lipophilic surfactants, respectively. 1,3,6,8-Pyrenetetrasulfonic acid tetrasodium salt (PTSA) was used as a hydrophilic model compound of a bioactive substance. Membrane filtration of a coarse W\\/O\\/W emulsion prepared with a rotor\\/stator homogenizer produced

Motohiro Shima; Yohei Kobayashi; Takao Fujii; Miyono Tanaka; Yukitaka Kimura; Shuji Adachi; Ryuichi Matsuno

2004-01-01

238

Modified Montmorillonite Clay Microparticles for Stable Oil-in-Seawater Emulsions.  

PubMed

Environmentally benign clay particles are of great interest for the stabilization of Pickering emulsions. Dodecane-in-synthetic seawater (SSW) emulsions formed with montmorillonite (MMT) clay microparticles modified with bis(2-hydroxyethyl)oleylamine were stable against coalescence, even at clay concentrations down to 0.1% w/v. Remarkably, as little as 0.001% w/v surfactant lowered the hydrophilicity of the clay to a sufficient level for stabilization of oil-in-SSW emulsions. The favorable effect of SSW on droplet size reduction and emulsion stability enhancement is hypothesized to be due to reduced electrostatic repulsion between adsorbed clay particles and a consequent increase in the continuous phase (an aqueous clay suspension) viscosity. Water/oil (W/O) emulsions were inverted to O/W either by decreasing the mass ratio of surfactant-to-clay (transitional inversion) or by increasing the water volume fraction (catastrophic inversion). For both types of emulsions, coalescence was minimal and the sedimentation or creaming was highly correlated with the droplet size. For catastrophic inversions, the droplet size of the emulsions was smaller in the case of the preferred curvature. Suspensions of concentrated clay in oil dispersions in the presence of surfactant were stable against settling. The mass transfer pathways during emulsification of oil containing the clay particles were analyzed on the droplet size/stability phase diagrams to provide insight for the design of dispersant systems for remediating surface and subsurface oceanic oil spills. PMID:24932773

Dong, Jiannan; Worthen, Andrew J; Foster, Lynn M; Chen, Yunshen; Cornell, Kevin A; Bryant, Steven L; Truskett, Thomas M; Bielawski, Christopher W; Johnston, Keith P

2014-07-23

239

Rheology of oil in water emulsions with added kaolinite clay  

SciTech Connect

This paper deals with the rhelogical measurements of oil in water emulsions with added kaolinite clay. The percent oil concentration, solids-free basis, was varied up to 70% by volume. The volume fraction of clay was varied up to 0.2 based on the total volume. The clay/emulsion mixtures displayed shear thinning behavior. Yield stress was observed, and its value increased with clay volume fraction and with oil concentration. The shear stress versus shear rate data could be fitted by the Casson model for low oil concentrations (below 40%) and by the Herschel-Bulkley model for higher oil concentrations. On the basis of the experimental data, a correlation was developed to evaluate the relative viscosity of the clay/emulsion mixtures, where the relative viscosity was defined as the ratio of the viscosity of clay/emulsion mixtures to that of emulsions alone. A viscosity equation was also developed for calculating the viscosity of clay/emulsion mixtures.

Yan, Y.; Pal, R.; Masliyah, J. (Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical Engineering)

1991-08-01

240

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

2011-06-01

241

Interaction of nonionic surfactant AEO9 with ionic surfactants*  

PubMed Central

The interaction in two mixtures of a nonionic surfactant AEO9 (C12H25O(CH2CH2O)9H) and different ionic surfactants was investigated. The two mixtures were AEO9/sodium dodecyl sulfate (SDS) and AEO9/cetyltrimethylammonium bromide (CTAB) at molar fraction of AEO9, ? AEO9=0.5. The surface properties of the surfactants, critical micelle concentration (CMC), effectiveness of surface tension reduction (? CMC), maximum surface excess concentration (? max) and minimum area per molecule at the air/solution interface (A min) were determined for both individual surfactants and their mixtures. The significant deviations from ideal behavior (attractive interactions) of the nonionic/ionic surfactant mixtures were determined. Mixtures of both AEO9/SDS and AEO9/CTAB exhibited synergism in surface tension reduction efficiency and mixed micelle formation, but neither exhibited synergism in surface tension reduction effectiveness.

Zhang, Zhi-guo; Yin, Hong

2005-01-01

242

Development and Evaluation of Emulsions from Carapa guianensis (Andiroba) Oil  

PubMed Central

Carapa guianensis, a popular medicinal plant known as “Andiroba” in Brazil, has been used in traditional medicine as an insect repellent and anti-inflammatory product. Additionally, this seed oil has been reported in the literature as a repellent against Aedes aegypti. The aim of this work is to report on the emulsification of vegetable oils such as “Andiroba” oil by using a blend of nonionic surfactants (Span 80® and Tween 20®), using the critical hydrophilic–lipophilic balance (HLB) and pseudo-ternary diagram as tools to evaluate the system’s stability. The emulsions were prepared by the inverse phase method. Several formulations were made according to a HLB spreadsheet design (from 4.3 to 16.7), and the products were stored at 25°C and 4°C. The emulsion stabilities were tested both long- and short-term, and the more stable one was used for the pseudo-ternary diagram study. The emulsions were successfully obtained by a couple of surfactants, and the HLB analysis showed that the required HLB of the oil was 16.7. To conclude, the pseudo-ternary diagram identified several characteristic regions such as emulsion, micro-emulsion, and separation of phases.

Ferreira, Magda R. A.; Santiago, Rosilene R.; de Souza, Tatiane P.; Egito, Eryvaldo S. T.; Oliveira, Elquio E.

2010-01-01

243

Thermodynamically Stable Pickering Emulsions Stabilized by Janus Dumbbells  

NASA Astrophysics Data System (ADS)

Janus particles have two sides with different, often opposite, surface properties. Janus dumbbell is one type of Janus particles that consists of two partially fused spherical lobes. It is possible to independently control the geometry and surface wettability of Janus dumbbells. Janus dumbbells can also be produced in a large quantity, making them useful for practical applications such as emulsion stabilization. In this work, we calculate the free energy of emulsion formation using amphiphilic Janus dumbbells as solid surfactants. In contrast to kinetically stable emulsions stabilized by homogeneous particles, emulsion stabilized by Janus dumbbells can be thermodynamically stable. There also exists an optimal radius of droplets that can be stabilized by infinite or limited number of amphiphilic dumbbells in the continuous phase. We demonstrate that the optimal radius of dumbbell-stabilized droplets can be predicted based on the volume of the dispersed phase and the volume fraction of dumbbells in the continuous phase. We believe our calculation will provide guidelines for using Janus dumbbells as colloid surfactants to generate stable emulsions.

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

2013-03-01

244

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

2012-12-15

245

Method of breaking and emulsion and an emulsion-emulsion breaker composition  

SciTech Connect

This invention relates to a composition of matter and to a method for producing a controllable, residue-free break of an emulsion or a dispersion of a water-in-oil emulsion. An emulsion breaker is incorporated into the emulsion. It is temporarily-protected (deactivated) so that breaking of the emulsion is initially avoided. By removing the protection, the breaker becomes active, and it acts to break the emulsion into its separate phases.

Salathiel, W. M.

1985-05-14

246

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

247

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

248

Demulsification of Gas Oil\\/Water Emulsion via High Intensity Ultrasonic Standing Wave  

Microsoft Academic Search

High intensity ultrasonic standing wave field was established in a horizontal direction and its effect on “gas oil” in “water” emulsion separation rate was studied. Also, effects of four parameters on emulsion instability behavior were investigated: ultrasound irradiation time(5-30 min), emulsion position in ultrasound field(17-37 cm), ultrasound input intensity(20,45 and 75%) and dispersed phase concentration(0.5,2 and 10%). Emulsion light absorbance, droplet diameter

H. Ghafourian Nasiri; M. T. Hamed Mosavian; R. Kadkhodaee

2012-01-01

249

Optimization of perfluoro nano-scale emulsions: the importance of particle size for enhanced oxygen transfer in biomedical applications.  

PubMed

Nano-scale emulsification has long been utilized by the food and cosmetics industry to maximize material delivery through increased surface area to volume ratios. More recently, these methods have been employed in the area of biomedical research to enhance and control the delivery of desired agents, as in perfluorocarbon emulsions for oxygen delivery. In this work, we evaluate critical factors for the optimization of PFC emulsions for use in cell-based applications. Cytotoxicity screening revealed minimal cytotoxicity of components, with the exception of one perfluorocarbon utilized for emulsion manufacture, perfluorooctylbromide (PFOB), and specific w% limitations of PEG-based surfactants utilized. We optimized the manufacture of stable nano-scale emulsions via evaluation of: component materials, emulsification time and pressure, and resulting particle size and temporal stability. The initial emulsion size was greatly dependent upon the emulsion surfactant tested, with pluronics providing the smallest size. Temporal stability of the nano-scale emulsions was directly related to the perfluorocarbon utilized, with perfluorotributylamine, FC-43, providing a highly stable emulsion, while perfluorodecalin, PFD, coalesced over time. The oxygen mass transfer, or diffusive permeability, of the resulting emulsions was also characterized. Our studies found particle size to be the critical factor affecting oxygen mass transfer, as increased micelle size resulted in reduced oxygen diffusion. Overall, this work demonstrates the importance of accurate characterization of emulsification parameters in order to generate stable, reproducible emulsions with the desired bio-delivery properties. PMID:22652356

Fraker, Christopher A; Mendez, Armando J; Inverardi, Luca; Ricordi, Camillo; Stabler, Cherie L

2012-10-01

250

Mixed micelle behavior of Pluronic L64 and Triton X-100 with conventional and dimeric cationic surfactants  

Microsoft Academic Search

The mixed micellar properties of a triblock copolymer, Pluronic L64, (EO)13(PO)30(EO)13, and a nonionic surfactant, Triton X-100, in aqueous solution with conventional alkyl ammonium bromides and their dimeric homologues were investigated with the help of fluorescence and cloud point measurements. The composition of mixed micelles and the interaction parameter, ?, evaluated from the critical micelle concentration (cmc) data for different

Mandeep Singh Bakshi; Shweta Sachar; Kulbir Singh; Arifa Shaheen

2005-01-01

251

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

252

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

253

Nonionic block polymer surfactants enhance immunogenicity of pneumococcal hexasaccharide-protein vaccines.  

PubMed Central

Incorporated in oil-in-water emulsions, nonionic block polymer surfactants change the kinetics of generated antibody responses against pneumococcal hexasaccharide-protein conjugates: prolonged immunoglobulin M and immunoglobulin G responses are realized. Nonionic block polymer surfactants favor the immunogenicity of hexasaccharide-protein conjugates in young mice in such a way that a single injection yields long-lasting protection.

Zigterman, G J; Snippe, H; Jansze, M; Ernste, E B; De Reuver, M J; Willers, J M

1988-01-01

254

Compaction of DNA by gemini surfactants: effects of surfactant architecture.  

PubMed

The interaction between bacteriophage T4 DNA and cationic gemini surfactants was studied by the use of fluorescence microscopy. Upon addition of surfactant, DNA undergoes a transition from random coil to globule, with an intermediate coexistence region. The state behavior of a DNA-gemini surfactant system was found to depend on spacer length, valency, head group size, and tail length. A series of alkanediyl-alpha,omega-bis-(dimethylalkylammonium bromide) surfactants with fixed tail length and variable spacer length s showed a minimum of compaction efficiency at s=6 due to the competition between entropy loss and enthalpy gain. This occurs at roughly the same spacer length at which the critical micellization concentration shows a maximal value (at s=5). In comparison with a single-tailed divalent surfactant (12-3-1) it was shown that the two-tailed equivalent (12-3-12) was more efficient in compacting DNA. A series of gemini surfactants based on cationic peptides with a alpha,omega-diamino alkyl spacer showed similar behavior upon changing the spacer length. Additionally, two surfactants based on diastereomers of tartaric acid with hexadecanoic acid tails and alpha,omega-diaminopropanyl and spermidine head groups, respectively, showed effects of head group size that depended strongly on entropy effects. The dependence on valency of the head group is found to be similar to what is known for mono- and multivalent ions, the latter being more efficient per unit of charge. PMID:16290792

Karlsson, Lisa; van Eijk, Marcel C P; Söderman, Olle

2002-08-15

255

Effect of surfactants on the electrochemical behavior of LiFePO4 cathode material for lithium ion batteries  

NASA Astrophysics Data System (ADS)

The application of lithium iron phosphate as positive electrode material for lithium ion batteries has been challenged by its poor electronic conductivity. To improve its conductivity and electrochemical performance, we have synthesized LiFePO4/C composite cathode materials by sol gel technique using long chain fatty acids, such as, lauric, myristic, and oleic acids, as surfactants for carbon coating. The phase purity of the three LiFePO4/C composites was confirmed by X-ray diffraction. The Raman spectroscopy, scanning electron microscopy and transmission electron microscopy measurements show that the surfactants coat the LiFePO4 particles with carbon with varying degree of uniformity depending on the surfactant used. The sample prepared in presence of lauric acid shows smaller particle size and the lowest charge transfer resistance, higher Li-ion diffusion coefficient, higher discharge capacity (?155 mAh g-1 at C/3 rate), better rate capability and cyclic stability compared to the other two samples. We found the smaller particle size, uniformity of carbon coating, reduced agglomeration, and a lower amount of Fe3+ impurity phase in the samples to be major contributing factors for better electrochemical properties in the LiFePO4/C cathode material.

Bazzi, K.; Mandal, B. P.; Nazri, M.; Naik, V. M.; Garg, V. K.; Oliveira, A. C.; Vaishnava, P. P.; Nazri, G. A.; Naik, R.

2014-11-01

256

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

2013-04-23

257

Preparation of Stable Multiple W\\/O\\/W Emulsions Using Pluronic (Poloxamer):Poly(acrylic Acid) Complexes  

Microsoft Academic Search

A detailed study of the interactions between poly(acrylic acid) (PAA) and a range of hydrophilic poloxamer surfactants was undertaken. This enabled us to use the most appropriate combinations of these surfactants and PAA to prepare stable multiple w\\/o\\/w emulsions. Poly(acrylic acid) as Carbopol 907 was reacted with poloxamer surfactants in the forms of Pluronic F127, P104, P103, F68, P75, and

Mohammed Leadi Cole; Tony L. Whateley

1995-01-01

258

FAT EMULSION COMPOSITION ALTERS INTAKE AND THE EFFECTS OF BACLOFEN  

PubMed Central

Thickened oil-in-water emulsions are useful model foods in rat studies due to their high acceptance and similarity to foods consumed by humans. Previous work from this laboratory used oil-in-water emulsions thickened with a biopolymer blend containing starch. Intake and effects of baclofen, a GABA-B agonist that decreases fat intake and drug self-administration, were reported, but the contribution of starch was not assessed. In the present study, intake and effects of baclofen were assessed in rats using emulsions prepared with two fat types (32% vegetable shortening, 32% corn oil) and thickened with three biopolymer blends. One biopolymer blend contained starch and the other two did not. Daily 1-h intake of the vegetable shortening emulsion containing starch was significantly greater than the other emulsions. When starch was added to the emulsions originally containing no starch, intake significantly increased. Baclofen generally reduced intake of all emulsions regardless of starch content and stimulated intake of chow. However, effects were more often significant for vegetable shortening emulsions. This report: 1) demonstrates that products used to prepare thickened oil-in-water emulsions have significant effects on rat ingestive behavior, and 2) confirms the ability of baclofen to reduce consumption of fatty foods, while simultaneously stimulating intake of chow.

Wang, Y; Wilt, DC; Wojnicki, FHE; Babbs, RK; Coupland, JN; Corwin, RLC

2011-01-01

259

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

260

Colloidal and Physicochemical Characterization of Highly Magnetic O\\/W Magnetic Emulsions  

Microsoft Academic Search

A study of magnetic emulsion droplets is reported using various analytical and physico?chemical techniques. The chemical composition of the droplets (i.e., the amount of iron oxide, organic phase, and surfactant) is determined using the combination of thermogravimetry, elemental analysis, and gas chromatography. The electrokinetic properties of the magnetic emulsion are investigated as a function of pH and ionic strength in

Franck Montagne; Sébastien Braconnot; Christian Pichot; Abdelhamid Elaïssari

2003-01-01

261

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

262

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

263

Ion-responsive behavior of ionic-liquid surfactant aggregates with applications in controlled release and emulsification.  

PubMed

We propose a simple but efficient, rapid, and quantitative ion-responsive micelle system based on counter-anion exchange of a surfactant with an imidazolium unit. The ion-exchange reaction results in the amphiphilic-to-hydrophobic transition of the imidazolium salt, leading to the destruction of the micelles, which has been successfully applied to controlled release and emulsification. The proposed design offers a novel alternative stimulus to control these smart physical aggregates besides pH, temperature and light-with extra advantages. Our finding greatly benefits both fundamental research and industry. PMID:18932155

Shen, Yanfei; Zhang, Yuanjian; Kuehner, Daniel; Yang, Guifu; Yuan, Fuyu; Niu, Li

2008-10-24

264

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

2013-11-01

265

Emulsion atom transfer radical polymerization of 2-ethylhexyl methacrylate  

Microsoft Academic Search

The emulsion atom transfer radical polymerization (ATRP) of 2-ethylhexyl methacrylate (EHMA) was carried out with ethyl 2-bromoisobutyrate (EBiB) as an initiator and copper bromide (CuBr)\\/4,4?-dinonyl-2,2?-bipyridyl (dNbpy) as a catalyst system. The effects of surfactant type and concentration, temperature, monomer\\/initiator ratio, and CuBr2 addition on the system livingness, polymer molecular weight control, and latex stability were examined in detail. It was

Hormoz Eslami; Shiping Zhu

2005-01-01

266

A one-step process to a Janus emulsion.  

PubMed

Aqueous high internal phase volume ratio (O/W 90/10) Janus emulsions of a vegetable oil and a silicone fluid were prepared in a single step emulsification by the common vibrator equipment. The basis for the unique structure is discussed in relation to pair-wise interactions between the components with especial emphasis on the surfactant concentration in the aqueous phase. PMID:20970807

Hasinovic, Hida; Friberg, Stig E; Rong, Guo

2011-02-01

267

Preparation of a stable double emulsion (W 1\\/O\\/W 2): role of the interfacial films on the stability of the system  

Microsoft Academic Search

This paper presents new protocols enabling preparation of W1\\/O\\/W2 double emulsions: one, using soybean oil as the O phase, that yields edible emulsions with industrial applications, and a second that yields emulsions with a previously unattainable concentration 15% (w\\/w) of surfactants in the external phase (the 15% target was chosen to meet the typical industry standard). Preparation of a stable

M Kanouni; H. L Rosano; N Naouli

2002-01-01

268

Nanoparticle Associated Surfactant Micellar Fluids  

NASA Astrophysics Data System (ADS)

Surfactant micellar fluids, or viscoelastic surfactant fluids, have been used in the oil industry as completion and stimulation fluids. High fluid leak-off and low thermal stability at elevated temperatures have, however, limited their application for hydraulic fracturing and frac-packing applications. Improved thermal stability and rheological design of such viscoelastic surfactants is critical for non-formation damaging, high temperature well treatments. This paper will introduce the interaction of nanoparticles with micelles, which at low concentrations induce micelle-micelle associations and significantly improve the performance of viscoelastic surfactant fluids. The unique association of viscoelastic surfactant micelles and nanoparticles has demonstrated improved viscosity, the formation of a ``pseudo-filtercake'', and enhanced thermal stability. Laboratory tests show the development of a pseudo-filtercake which significantly reduces the rate of fluid loss and demonstrates wall-building rather than viscosity dependant leak-off control. Rheological tests demonstrate long-term stability of viscoelastic behavior at 76.7 °C for fluids with moderate surfactant concentrations. Temperature stability can be achieved up to 135 °C using lower surfactant concentrations (1%v-2%v) than conventionally known. Oscillatory measurements of the linear viscoelasticity demonstrate significant differences in fluid structure with the addition of nanoparticles

Maxey, Jason; Crews, James; Huang, Tianping

2008-07-01

269

Solvent-free formation of hydroxyapatite coated biodegradable particles via nanoparticle-stabilized emulsion route  

NASA Astrophysics Data System (ADS)

Hydroxyapatite (HAp) nanoparticle-coated biodegradable polymer particles were fabricated from a nanoparticle-stabilized emulsion in the absence of any molecular surfactants or organic solvents. First, a polymer melt-in-water emulsion was prepared by mixing a water phase containing nanosized HAp particles as a particulate emulsifier and an oil phase consisting of poly(?-caprolactone) (PCL) or poly(L-lactide-co-?-caprolactone) (P(LLA-CL)) above its melting point. It was clarified that the interaction between ester/carboxyl groups of the polymers and the HAp nanoparticles at the polymer-water interface played a crucial role to prepare the nanoparticle-stabilized emulsion. The HAp nanoparticle-coated biodegradable polymer particle (a polymer solid-in-water emulsion) was fabricated by cooling the emulsion. The particle morphology and particle size were evaluated using scanning electron microscope.

Okada, Masahiro; Fujii, Syuji; Nishimura, Taiki; Nakamura, Yoshinobu; Takeda, Shoji; Furuzono, Tsutomu

2012-12-01

270

Magnetoresistive emulsion analyzer.  

PubMed

We realize a magnetoresistive emulsion analyzer capable of detection, multiparametric analysis and sorting of ferrofluid-containing nanoliter-droplets. The operation of the device in a cytometric mode provides high throughput and quantitative information about the dimensions and magnetic content of the emulsion. Our method offers important complementarity to conventional optical approaches involving ferrofluids, and paves the way to the development of novel compact tools for diagnostics and nanomedicine including drug design and screening. PMID:23989504

Lin, Gungun; Baraban, Larysa; Han, Luyang; Karnaushenko, Daniil; Makarov, Denys; Cuniberti, Gianaurelio; Schmidt, Oliver G

2013-01-01

271

Microfluidics with Gel Emulsions  

Microsoft Academic Search

Microfluidic processing is usually achieved using single phase liquids. Instead, we use monodisperse emulsions to compartment liquids within microchannel geometries. At low continuous phase volume fractions, droplets self-organize to form well-defined arrangements, analogous to foam. While it is well-known that confined geometries can induce rearrangement of foam compartments at the millimeter-scale, similar dynamics are also expected for gel emulsions. We

Craig Priest; Enkhtuul Surenjav; Stephan Herminghaus; Ralf Seemann

2006-01-01

272

Magnetoresistive Emulsion Analyzer  

NASA Astrophysics Data System (ADS)

We realize a magnetoresistive emulsion analyzer capable of detection, multiparametric analysis and sorting of ferrofluid-containing nanoliter-droplets. The operation of the device in a cytometric mode provides high throughput and quantitative information about the dimensions and magnetic content of the emulsion. Our method offers important complementarity to conventional optical approaches involving ferrofluids, and paves the way to the development of novel compact tools for diagnostics and nanomedicine including drug design and screening.

Lin, Gungun; Baraban, Larysa; Han, Luyang; Karnaushenko, Daniil; Makarov, Denys; Cuniberti, Gianaurelio; Schmidt, Oliver G.

2013-08-01

273

Magnetoresistive Emulsion Analyzer  

PubMed Central

We realize a magnetoresistive emulsion analyzer capable of detection, multiparametric analysis and sorting of ferrofluid-containing nanoliter-droplets. The operation of the device in a cytometric mode provides high throughput and quantitative information about the dimensions and magnetic content of the emulsion. Our method offers important complementarity to conventional optical approaches involving ferrofluids, and paves the way to the development of novel compact tools for diagnostics and nanomedicine including drug design and screening.

Lin, Gungun; Baraban, Larysa; Han, Luyang; Karnaushenko, Daniil; Makarov, Denys; Cuniberti, Gianaurelio; Schmidt, Oliver G.

2013-01-01

274

The effect of additives on the treatment of oil-in-water emulsions by vacuum evaporation.  

PubMed

A simple batch vacuum evaporation process for the treatment of several oil-in-water (O/W) emulsions is reported. The experiments were carried out with waste emulsions from an industrial copper rolling process and with model emulsions prepared in the laboratory. No detailed information on the formulation of the industrial waste O/W emulsions was available. Several model emulsions were formulated using the same base oil (an 85-15% (w/w) mixture of a synthetic poly-alpha-olefin and a trimethylol propane trioleate ester, respectively) and one of the three following surfactants: Brij-76 (polyethylene glycol octadecyl ether, non-ionic), CTAB (hexadecyltrimethyl ammonium bromide, cationic), and Oleth-10 (glycolic acid ethoxylate oleyl ether, anionic). Experimental results show a strong influence of operating conditions, such as pressure or bath temperature, on the evaporation performance. As a general trend, the higher the values of these parameters, the higher the pollutant content in the obtained aqueous effluent. The presence of surfactants increase the evaporation rate, especially at low operating vacuum pressures, the solubility of oil molecules in water and the evaporation temperature of model O/W emulsions. Furthermore, COD reductions higher than 99.5% for the treated waste O/W emulsions were achieved. PMID:17321675

Gutiérrez, Gemma; Cambiella, Angel; Benito, José M; Pazos, Carmen; Coca, José

2007-06-18

275

Highly magnetizable superparamagnetic colloidal aggregates with narrowed size distribution from ferrofluid emulsion.  

PubMed

The formation of spherical superparamagnetic colloidal aggregates of magnetite nanoparticles by emulsification of a ferrofluid and subsequent solvent evaporation has been systematically studied. The colloidal aggregates occur as a dense sphere with magnetite nanoparticles randomly packed and preserved particle-particle separation due to chemisorbed oleic acid. The voids between nanoparticles are filled with solvent and free oleic acid. The latter was found to influence the formation of colloidal aggregates and their surface properties. The choice of surfactant, whether low molecular weight or polymeric, was shown to lead to the colloidal aggregates having tailored interfacial behavior. Magnetization measurements at ambient temperature revealed that the magnetite colloidal aggregates preserve the superparamagnetic properties of the starting nanoparticle units and show high saturation magnetization values up to 57 emu/g. The size distribution of magnetite nanoparticle colloidal aggregates produced by such an approach was found to be a function of emulsion droplet breakup-coalescence and stabilization kinetics and therefore is influenced by the emulsification process conditions and concentrations of the emulsion compounds. PMID:22365838

Lobaz, Volodymyr; Klupp Taylor, Robin N; Peukert, Wolfgang

2012-05-15

276

Semi-solid Sucrose Stearate-Based Emulsions as Dermal Drug Delivery Systems  

PubMed Central

Mild non-ionic sucrose ester surfactants can be employed to produce lipid-based drug delivery systems for dermal application. Moreover, sucrose esters of intermediate lipophilicity such as sucrose stearate S-970 possess a peculiar rheological behavior which can be employed to create highly viscous semi-solid formulations without any further additives. Interestingly, it was possible to develop both viscous macroemulsions and fluid nanoemulsions with the same chemical composition merely by slight alteration of the production process. Optical light microscopy and cryo transmission electron microscopy (TEM) revealed that the sucrose ester led to the formation of an astonishing hydrophilic network at a concentration of only 5% w/w in the macroemulsion system. A small number of more finely structured aggregates composed of surplus surfactant were likewise detected in the nanoemulsions. These discoveries offer interesting possibilities to adapt the low viscosity of fluid O/W nanoemulsions for a more convenient application. Moreover, a simple and rapid production method for skin-friendly creamy O/W emulsions with excellent visual long-term stability is presented. It could be shown by franz-cell diffusion studies and in vitro tape stripping that the microviscosity within the semi-solid formulations was apparently not influenced by their increased macroviscosity: the release of three model drugs was not impaired by the complex network-like internal structure of the macroemulsions. These results indicate that the developed semi-solid emulsions with advantageous application properties are highly suitable for the unhindered delivery of lipophilic drugs despite their comparatively large particle size and high viscosity.

Klang, Victoria; Schwarz, Julia C.; Matsko, Nadejda; Rezvani, Elham; El-Hagin, Nivine; Wirth, Michael; Valenta, Claudia

2011-01-01

277

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

278

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

279

pH-dependent and pH-independent self-assembling behavior of surfactant-like peptides  

NASA Astrophysics Data System (ADS)

Self-assembly of amphiphilic peptides designed during the last years by several research groups leads to a large variety of 3D-structures that already found applications in stabilization of large protein complexes, cell culturing systems etc. In this report, we present synthesis and characterization of two novel families of amphiphilic peptides KAn and KAnW (n=6,5,4) that exhibits clear charge separation controllable by pH of the environment. As the pH changes from acidic to basic, the charge on the ends of the peptide molecule varies eventually leading to reorganization of KAn micelles and even micellar inversion. On contrary, the bulky geometry of the tryptophan residue in KAnW limits the variation of the surfactant parameter and hence largely prevents assembly into spherical or cylindrical micelles while favouring flatter geometries. The studied short peptide families demonstrate formation of ordered aggregates with well-defined secondary structure from short unstructured peptides and provide a simple system where factors responsible for self-assembly can be singled out and studied one by one. The ability to control the shape and structure of peptide aggregates can provide basis for novel designer pH sensitive materials including drug delivery and controlled release systems.

Gurevich, Leonid; Fojan, Peter

2012-02-01

280

Examining the formulation of emulsion electrospinning for improving the release of bioactive proteins from electrospun fibers.  

PubMed

Emulsion electrospinning has been sought as a method to prepare fibrous materials/scaffolds for growth factor delivery. Emulsion conditions, specifically sonication and the addition of a surfactant, were evaluated to determine their effect on the release and bioactivity of proteins from electrospun scaffolds. Polycaprolactone (PCL) and poly(ethylene oxide) (PEO/PCL) blends were evaluated where PEO, a hydrophilic polymer, was shown to enhance the incorporation of proteins. Electrospun scaffolds prepared with the addition of the nonionic surfactant Span® 80 at a concentration greater than the critical micelle concentration followed by mild sonication (10% amplitude) released lysozyme, the model protein, with a higher level of bioactivity as compared with other surfactant and sonication conditions. These conditions were then used to prepare emulsions of platelet-derived growth factor-BB (PDGF-BB) in PEO/PCL blends. Electrospun mats prepared by emulsions consisting of PDGF-BB incorporated with Span® 80 and sonicated at 10% amplitude exhibited a controlled release of PDGF-BB over 96 h as compared with a more rapid release from solutions that were not emulsified (Direct Addition) or emulsions that did not receive Span® 80 or sonication. Bioactive PDGF-BB incorporated in electrospun scaffolds enhanced the osteogenic differentiation of human mesenchymal stem cells as evidenced by increased alkaline phosphatase activity, improved cell attachment and reorganized cytoskeletal filaments. The findings in this study provide improved methods for achieving controlled release of bioactive proteins from electrospun materials. PMID:23554256

Briggs, Tonye; Arinzeh, Treena Livingston

2014-03-01

281

Emulsions for interfacial filtration.  

SciTech Connect

We have investigated a novel emulsion interfacial filter that is applicable for a wide range of materials, from nano-particles to cells and bacteria. This technology uses the interface between the two immiscible phases as the active surface area for adsorption of targeted materials. We showed that emulsion interfaces can effectively collect and trap materials from aqueous solution. We tested two aqueous systems, a bovine serum albumin (BSA) solution and coal bed methane produced water (CBMPW). Using a pendant drop technique to monitor the interfacial tension, we demonstrated that materials in both samples were adsorbed to the liquid-liquid interface, and did not readily desorb. A prototype system was built to test the emulsion interfacial filter concept. For the BSA system, a protein assay showed a progressive decrease in the residual BSA concentration as the sample was processed. Based on the initial prototype operation, we propose an improved system design.

Grillet, Anne Mary; Bourdon, Christopher Jay; Souza, Caroline Ann; Welk, Margaret Ellen; Hartenberger, Joel David; Brooks, Carlton, F.

2006-11-01

282

Role of naphthenic acids in stabilizing water-in-diluted model oil emulsions.  

PubMed

The need for alkaline conditions in oil sands processing is, in part, to produce natural surfactants from bitumen. Previous studies have shown that the produced surfactants are primarily carboxylic salts of naphthenic acids with the possibility of sulfonic salts as well. The role of these natural surfactants, particularly those in the naphthenate class, is to provide a physicochemical basis for several subprocesses in bitumen extraction. In this study, it was found that the content of indigenous naphthenic acids in bitumen can destabilize, to some extent, the water-in-oil emulsion by lowering the interfacial tension, reducing the rigidity and promoting the coalescence of water droplets. PMID:20496916

Gao, Song; Moran, Kevin; Xu, Zhenghe; Masliyah, Jacob

2010-06-17

283

Interfacial properties of carbon particulate-laden liquid interfaces and stability of related foams and emulsions  

Microsoft Academic Search

Aqueous dispersions of carbon black and carbon soot containing the cationic surfactant CTAB have been investigated from the point of view of dynamic interfacial tension and surface dilational rheology. In addition the features and stability of emulsions and foams formed from these dispersions have been studied and correlated with the interfacial properties.The results show an interaction of the carbonaceous particles

Eva Santini; Francesca Ravera; Michele Ferrari; Michela Alfè; Anna Ciajolo; Libero Liggieri

2010-01-01

284

Droplet size and stability of nano-emulsions produced by the temperature phase inversion method  

Microsoft Academic Search

We studied the formation and stability of n-decane in water nano-emulsions produced by the phase inversion temperature (PIT) emulsification method using polyoxyethylene lauryl ether as surfactant. The results obtained indicate that the droplet size and size distribution are strongly dependent on the methods of heating and cooling, and on the final temperature to which the mixture is cooled after phase

Sher Lin Ee; Xiumei Duan; Jeffery Liew; Q. Dzuy Nguyen

2008-01-01

285

Development of W\\/O emulsion to form harmless ice slurry to human being  

Microsoft Academic Search

In order to form ice slurry in ice storage, W\\/O emulsion was made from water–oil mixture with a small amount of surfactant. And, it was proved that ice slurry could be formed even in a metal vessel, which is expected to improve ice formation rate, without ice adhesion to a cooling vessel wall because of a structural feature of the

Koji Matsumoto; Kengo Matsumoto

2009-01-01

286

Preparation and evaluation of w/o/w type emulsions containing vancomycin.  

PubMed

The objective of this contribution is to summarize the preparation and application of water-in-oil-in-water type multiple emulsions (w/o/w emulsions) entrapping vancomycin (VCM). Formulations of the emulsions (the composition of an oily phase or the type and concentrations of surfactants) and emulsification methods (a stirring method and a membrane method) or conditions (rotation rates, pore sizes of membrane or operation pressures) were evaluated in order to prepare stable w/o/w emulsions. The pharmaceutical properties of the w/o/w emulsions - particle sizes, viscosity, phase separation and drug entrapment efficiency were measured and evaluated. We prepared stable w/o/w emulsions with a particle size of about 3 micrometer and an entrapment efficiency of VCM of about 70%. When this emulsion was administered intravenously to rats, plasma concentrations of VCM were prolonged compared to the VCM solution alone. The results of this study show the potential of the w/o/w emulsions for several clinical applications as one of the drug delivery systems. PMID:11104894

Okochi, H; Nakano, M

2000-12-01

287

Influence of PEG-12 Dimethicone addition on stability and formation of emulsions containing liquid crystal.  

PubMed

Oil/water emulsions, containing liquid crystals, were developed employing Andiroba oil, PEG-12 Dimethicone and Crodafos CES. It was evaluated the influence of silicone surfactants on the emulsions stability and on the formation of liquid crystalline phases and therefore, physicochemical characteristics, such as rheology and zeta potential, were evaluated. Emulsions were prepared by the emulsions phase inversion method. All the formulations presented lamellar liquid crystalline phases. The PEG-12 Dimethicone addition did not change microscopically the liquid crystalline phases. The emulsions containing silicone demonstrated lower viscosity than those without the additive. This is an important feature, as the silicone did not change the rheological profile; however, the addition of silicone still can be used as a viscosity controller. The formulations had their viscosity increased 15 and 150 days after their preparation. This characteristic shows that the emulsions have their organization increased along the storing time. In the analysis of zeta potential, we could verify that all formulations presented negative values between -39.7 and -70.0 mV. Within this range of values, the emulsion physical stability is high (Fig. 10). It was concluded that the addition of PEG-12 Dimethicone kept the liquid crystalline phase of the emulsion obtained with Crodafos CES, influencing in a positive way in the system stability. PMID:18489351

Andrade, F F; Santos, O D H; Oliveira, W P; Rocha-Filho, P A

2007-06-01

288

Can Pickering emulsion formation aid the removal of creosote DNAPL from porous media?  

PubMed

The purpose of this investigation was to examine the proposition that creosote, emplaced in an initially water saturated porous system, can be removed from the system through Pickering emulsion formation. Pickering emulsions are dispersions of two immiscible fluids in which coalescence of the dispersed phase droplets is hindered by the presence of colloidal particles adsorbed at the interface between the two immiscible fluid phases. Particle trapping is strongly favoured when the wetting properties of the particles are intermediate between strong water wetting and strong oil wetting. In this investigation the necessary chemical conditions for the formation of physically stable creosote-in-water emulsions protected against coalescence by bentonite particles were examined. It was established that physically stable emulsions could be formed through the judicious addition of small amounts of sodium chloride and the surfactant cetyl-trimethylammonium bromide. The stability of the emulsions was initially established by visual inspection. However, experimental determinations of emulsion stability were also undertaken by use of oscillatory rheology. Measurements of the elastic and viscous responses to shear indicated that physically stable emulsions were obtained when the viscoelastic systems showed a predominantly elastic response to shearing. Once the conditions were established for the formation of physically stable emulsions a "proof-of-concept" chromatographic experiment was carried out which showed that creosote could be successfully removed from a saturated model porous system. PMID:17988711

Torres, Luis; Iturbe, Rosario; Snowden, M J; Chowdhry, Babur; Leharne, Stephen

2008-03-01

289

Spontaneous Emulsification of Oils Containing Hydrocarbon, Nonionic Surfactant, and Oleyl Alcohol.  

PubMed

Phase behavior and videomicroscopy experiments were used to investigate spontaneous emulsification of n-hexadecane/oleyl alcohol/C12E6 mixtures in water at 30 degreesC. It was found that complete emulsification of a drop of the oil phase to form small oil droplets having diameters of about 1 µm occurred only when diffusion of water into the initial oil drop first converted it completely into the lamellar liquid crystalline phase and/or a microemulsion and then caused this phase (or these phases) to become supersaturated in oil so that many oil droplets nucleated. This behavior occurred when the hydrocarbon/alcohol ratio of the initial oil drop was near that of the excess oil phase for a balanced system at this temperature, i.e., at the phase inversion temperature (PIT), and when surfactant content was sufficiently high. The stability of these emulsions was investigated by means of turbidity measurements. The most stable emulsion appeared to occur under conditions where the drops were coated by a layer of the lamellar phase. Copyright 1999 Academic Press. PMID:9878151

Rang; Miller

1999-01-01

290

Rheology of oil in water emulsions with added kaolinite clay  

Microsoft Academic Search

This paper deals with the rhelogical measurements of oil in water emulsions with added kaolinite clay. The percent oil concentration, solids-free basis, was varied up to 70% by volume. The volume fraction of clay was varied up to 0.2 based on the total volume. The clay\\/emulsion mixtures displayed shear thinning behavior. Yield stress was observed, and its value increased with

Yuhua Yan; Rajinder Pal; Jacob Masliyah

1991-01-01

291

Surface shear inviscidity of soluble surfactants.  

PubMed

Foam and emulsion stability has long been believed to correlate with the surface shear viscosity of the surfactant used to stabilize them. Many subtleties arise in interpreting surface shear viscosity measurements, however, and correlations do not necessarily indicate causation. Using a sensitive technique designed to excite purely surface shear deformations, we make the most sensitive and precise measurements to date of the surface shear viscosity of a variety of soluble surfactants, focusing on SDS in particular. Our measurements reveal the surface shear viscosity of SDS to be below the sensitivity limit of our technique, giving an upper bound of order 0.01 ?N·s/m. This conflicts directly with almost all previous studies, which reported values up to 10(3)-10(4) times higher. Multiple control and complementary measurements confirm this result, including direct visualization of monolayer deformation, for SDS and a wide variety of soluble polymeric, ionic, and nonionic surfactants of high- and low-foaming character. No soluble, small-molecule surfactant was found to have a measurable surface shear viscosity, which seriously undermines most support for any correlation between foam stability and surface shear rheology of soluble surfactants. PMID:24563383

Zell, Zachary A; Nowbahar, Arash; Mansard, Vincent; Leal, L Gary; Deshmukh, Suraj S; Mecca, Jodi M; Tucker, Christopher J; Squires, Todd M

2014-03-11

292

Self-emulsifying pellets: relations between kinetic parameters of drug release and emulsion reconstitution-influence of formulation variables.  

PubMed

The effects of surfactant type and content on the kinetics of emulsion reconstitution and release of drugs differing in lipophilicity from self-emulsifying microcrystalline cellulose pellets were studied. Furosemide and propranolol were the drugs, medium-chain triglyceride was the oil, and Cremophors ELP, RH40, and RH60 were the surfactants. Pellets were prepared by extrusion/spheronization with emulsions (75% water and 25%, w/w, oil/surfactant/drug). Stability of the emulsions was evaluated from changes in the back-scattered light, and re-emulsification and drug release from light transmittance and UV spectroscopy, respectively. Emulsion stability increased because of the incorporation of the drugs. Re-emulsification depended only on the surfactant content and was expressed by a simple power equation (Ra2 > 0.945, Q(2) > 0.752). Drug release was expressed by two biexponential equations (Ra2 > 0.989, Q(2) > 0.699 and Ra2 > 0.947, Q(2) > 0.693) implying initial burst and terminal slow release phase and by the linear form (Lineweaver-Burke) of Michaelis-Menten equation (Ra2 > 0.726, Q(2) > 0.397). Relationships exist between the rate constants of the equations describing emulsion reconstitution and drug release, for propranolol compositions (R(2) = 0.915), and for compositions of both drugs with less hydrophilic ELP and RH40 (R(2) = 0.511), and also, among dissolution efficiency, drug solubility in oil/surfactant, and emulsion reconstitution ability, indicating the importance of drug solubilization in oil/surfactant and re-emulsification ability on drug release. PMID:24596121

Nikolakakis, Ioannis; Malamataris, Stavros

2014-05-01

293

Performance of Emulsion Explosives  

Microsoft Academic Search

Some performance of a number of emulsion explosives containing glass micro-baloons were studied experimentally and theoretically. For each of the explosives, detonation velocity was measured and calculated and ballistic mortar tests and cylinder expansion tests were carried out. The results obtained enables a comparison of the usefulness of both testing methods. The influence of some metal nitrates contained in the

S. Cudzilo; P. Kohlicek; V. A. Trzcinski; S. Zeman

2002-01-01

294

Kinetics of Emulsion Polymerization  

Microsoft Academic Search

As a basis for understanding emulsion polymerization, the kinetics of free radical reactions in isolated loci is discussed subject to the condition that the free radicals are supplied to the loci from an external source. Three cases of interest are considered: that in which the average number of free radicals per locus is small compared with unity, that in which

Wendell V. Smith; Roswell H. Ewart

1948-01-01

295

Crude Oil Emulsions. Abstracts.  

National Technical Information Service (NTIS)

On the occasion of this colloquium six lectures were held on the above-mentioned topic. These lectures dealt with composition, structure and transport behaviour of oil/water and water/oil emulsions, especially with the influence and effect of demulsifiers...

1988-01-01

296

Electrophoretic manipulation of multiple-emulsion droplets  

NASA Astrophysics Data System (ADS)

Electrophoretic manipulation of multiple-emulsion oil-in-water-in-oil (O/W)/O and water-in-oil-in-water-in-oil (W/O/W)/O core-shell droplets is shown. It was found that the electrophoretic mobility of the droplets is determined solely by the outer water shell, regardless of size or composition of the inner droplets. It was observed that the surface charge of the outer water shell can be changed and the polarity can be reversed through contact with a biased electrode in a similar way as with simple W/O droplets. Furthermore, addition of the anionic surfactant, sodium dodecyl sulfate to the outer water shell reverses the initial polarity and hence, electrophoretic mobility of the core-shell droplets before contact with an electrode. The results have practical implications for the manipulation of oil droplets in a continuous oil phase.

Schoeler, Andreas M.; Josephides, Dimitris N.; Chaurasia, Ankur S.; Sajjadi, Shahriar; Mesquida, Patrick

2014-02-01

297

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

298

Formation of 10-100 nm size-controlled emulsions through a sub-PIT cycle.  

PubMed

We have re-examined the phase inversion temperature (PIT) emulsification process. This is a low-energy method that uses a physicochemical drive to produce very fine oil/water emulsions in the absence of high shear flows. We used the polyoxyethylene 8 cetyl ether (C(16)E(8))/hexadecane/water system, which has a PIT of 76.2 degrees C. We find that successful emulsification depends on two conditions. First, the mixture must be stirred at low speed throughout the whole process: this makes it possible to produce emulsions at surfactant concentrations that are too low to form an equilibrium microemulsion. Second, the stirred mixtures must be heated above a threshold called the clearing boundary (CB) and then quenched to lower temperatures. The clearing boundary is determined experimentally by a minimum in the turbidity of the stirred mixture, which results from solubilization of all the oil into swollen micelles. This matches the emulsification failure boundary, and it is expressed mathematically by the condition R*C(0) = 1, where R* is the radius that results from the oil/surfactant composition for monodisperse spheres and C(0) is the spontaneous spherical curvature of the surfactant. Thus, we show that such cycles do not need to cross the PIT. In fact, sub-PIT cycles and cross-PIT cycles give exactly the same result. These conditions lead to emulsions that have a narrow size distribution and a mean diameter controlled by the oil/surfactant ratio. The typical range of those diameters is 20-100 nm. Moreover, these emulsions have an excellent metastability, in contrast with emulsions made with shorter oil and surfactant molecules. PMID:19899785

Roger, Kevin; Cabane, Bernard; Olsson, Ulf

2010-03-16

299

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

2013-09-10

300

Novel anhydrous emulsions: formulation as controlled release vehicles.  

PubMed

Novel anhydrous emulsions, which may offer some advantages as depot or reservoir vehicles for lipophilic drugs in controlled delivery systems, were formulated using castor oil as the disperse phase and dimethicone or cyclopentasiloxane as the continuous phase. Among the emulsifiers studied only silicone surfactants (cyclomethicone/dimethicone copolyols) which were miscible in silicone oil stabilized the emulsions. Cyclomethicone/PEG/PPG-18/18 Dimethicone and Cyclopentasiloxane/PEG/PPG-18/18 Dimethicone were more effective in lowering the interfacial tension between castor oil and both dimethicone and cyclopentasiloxane. Emulsions formulated using either of these two surfactants were found to be stable against phase separation and exhibited least globule growth over 168 h. The average particle size was found to be 2-6 microm in these systems formed by probe sonication. Slow release patterns of 3H-dehydroepiandrosterone (DHEA) and 3H-dexamethasone solubilized in the disperse castor oil phase into an aqueous dialyzing medium were observed over 48 h. PMID:15941632

Suitthimeathegorn, Orawan; Jaitely, Vikas; Florence, Alexander T

2005-07-25

301

Stability and Demulsification of Water-in-Crude Oil (w/o) Emulsions Via Microwave Heating  

NASA Astrophysics Data System (ADS)

Formation of emulsions during oil production and processing is a costly problem, both in terms of chemicals used and production losses. Experimental data are presented to show the influences of Triton X-100, Low sulphur Wax Residue (LSWR), Sorbitan monooleate (Span 83) and Sodium Dedocyl Sulphate (SDDS) on the stability and microwave demulsification of emulsions. It was found that emulsion stability was related to some parameters such as, the surfactant concentrations, water-oil phase ratio (10-90%), temperature and agitation speed. For economic and operational reasons, it is necessary to separate the water completely from the crude oils before transporting or refining them. In this regard, the present study found that microwave radiation method can enhance the demulsification of water-in-oil (w/o) emulsions in a very short time compared to the conventional heating methods.

Nour, Abdurahman. H.; Rosli; Yunus, Mohd.

302

Characterization and Demulsification of Water-in-crude Oil Emulsions  

NASA Astrophysics Data System (ADS)

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 stabilized the oil-water surfaces. The effect of chemical demulsifiers in demulsification of water-in-crude oil emulsions were assessed experimentally. The relative rates of water separation were characterized via graduated beakers. Four groups of demulsifier with different functional groups were used in this work namely amines, polyhydric alcohol, sulphonate and polymer. The effect of alcohol addition on demulsification performance also studied. The results obtained in this study have exposed the capability of chemical demulsifiers in destabilization of water-in-crude oil emulsions. Further works are nevertheless required to provide deeper understanding of the mechanisms involved to facilitate the development of an optimum system applicable to the industry.

Nour, Abdurahman H.; Abu Hassan, Mohd A.; Mohd Yunus, Rosli

303

Viscosity-Concentration Equation for Emulsions of Nearly Spherical Droplets.  

PubMed

A new modified form of the equation of N. Phan-Thien and D. C. Pham (J. Non-Newtonian Fluid Mech. 72, 305 (1997)) is proposed to describe the viscosity-concentration behavior of emulsions of nearly spherical droplets. The proposed equation, as well as other existing theoretical equations, is evaluated in light of a large body of experimental data on concentrated emulsions, covering a broad range of dispersed-phase to continuous-phase viscosity ratios (4.15x10(-3) to 1.17x10(3)). In general, the experimental data exhibit large deviations from the existing theoretical equations; for example, the theoretical equation of Phan-Thien and Pham underpredicts the relative viscosity of concentrated emulsions by a large amount. The equation proposed in this work describes the experimental viscosity data of different emulsion systems remarkably well. Copyright 2000 Academic Press. PMID:11082261

Pal

2000-11-01

304

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

2012-11-21

305

Precipitation of mixtures of anionic and cationic surfactants; 3: Effect of added nonionic surfactant  

SciTech Connect

The precipitation of an anionic surfactant by a cationic surfactant in the presence of a nonionic surfactant is examined. The precipitation domains for sodium dodecyl sulfate/dodecyl-pyridinium chloride were measured over a wide range of surfactant concentrations as a function of nonylphenol polyethoxylate concentration. Increasing the nonylphenol polyethoxylate concentration decreases the tendency for precipitation to occur. A model for predicting precipitation domains in ternary surfactant mixtures has been developed and verified experimentally. The model allows the nonionic surfactant to affect the precipitation behavior only by lowering the critical micelle concentration of the mixture. Small deviations between theory and experiments along part of the anionic-rich micelle boundary result from adsorption of SDS on the precipitate which gives the microcrystals a negative charge and prevents their growth to a visible size.

Shiau, B.J.; Harwell, J.H.; Scamehorn, J.F. (Univ. of Oklahoma, Norman, OK (United States). Inst. for Applied Surfactant Research)

1994-10-15

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

Evaluation of mixed surfactants for improved chemical flooding  

SciTech Connect

Phase behavior studies were conducted using combinations of a primary surfactant component and several ethoxylated surfactants. The objective of the study is to evaluate combinations of surfactants, anionic-nonionic and anionic-anionic mixtures, that would yield favorable phase behavior and solubilization capacity. The dependence of the solution behavior on the additive surfactant structure, surfactant type, oil, surfactant proportion, salinity, HLB, and temperature was observed. The results showed that the ethoxylated surfactants can improve the solution behavior of the overall system. The increase in optimum salinity range of these solutions corresponded to an increase in the degree of ethoxylation of additive surfactant, up to a certain limit. The nonionic surfactant additives yielded much higher salinities compared to the results from the ethoxylated anionics tested. The proportion of surfactant component in solution was critical in achieving a balance between the solubilization capacity and the enhancement in the system's salinity tolerance. Some combinations of these types of surfactants showed improved solution behavior with favorable solubilization capacity. The phase inversion temperature (PIT) method has been shown to be a relatively fast method for screening candidate surfactant systems. Comparisons were made using both the conventional salinity scan and the PIT method on selected chemical systems. The results showed good agreement between the salinity regions determined using both methods. A difference in the dependence of optimal salinity on HLB was observed for the different nonionics tested. The linear alkyl alcohol ethoxylates exhibited a behavior distinct from the dialkyl phenols at similar HLB levels with and without the primary sulfonate component in the solution. Other experiments performed at NIPER have shown that surfactant-enhanced alkaline flooding has good potential for the recovery of oil from Naval Petroleum Reserve Number 3 (NPR No. 3).

Llave, F.M.; French, T.R.; Lorenz, P.B.

1993-02-01

308

Evaluation of mixed surfactants for improved chemical flooding  

SciTech Connect

Phase behavior studies were conducted using combinations of a primary surfactant component and several ethoxylated surfactants. The objective of the study is to evaluate combinations of surfactants, anionic-nonionic and anionic-anionic mixtures, that would yield favorable phase behavior and solubilization capacity. The dependence of the solution behavior on the additive surfactant structure, surfactant type, oil, surfactant proportion, salinity, HLB, and temperature was observed. The results showed that the ethoxylated surfactants can improve the solution behavior of the overall system. The increase in optimum salinity range of these solutions corresponded to an increase in the degree of ethoxylation of additive surfactant, up to a certain limit. The nonionic surfactant additives yielded much higher salinities compared to the results from the ethoxylated anionics tested. The proportion of surfactant component in solution was critical in achieving a balance between the solubilization capacity and the enhancement in the system`s salinity tolerance. Some combinations of these types of surfactants showed improved solution behavior with favorable solubilization capacity. The phase inversion temperature (PIT) method has been shown to be a relatively fast method for screening candidate surfactant systems. Comparisons were made using both the conventional salinity scan and the PIT method on selected chemical systems. The results showed good agreement between the salinity regions determined using both methods. A difference in the dependence of optimal salinity on HLB was observed for the different nonionics tested. The linear alkyl alcohol ethoxylates exhibited a behavior distinct from the dialkyl phenols at similar HLB levels with and without the primary sulfonate component in the solution. Other experiments performed at NIPER have shown that surfactant-enhanced alkaline flooding has good potential for the recovery of oil from Naval Petroleum Reserve Number 3 (NPR No. 3).

Llave, F.M.; French, T.R.; Lorenz, P.B.

1993-02-01

309

Surfactant-lactoperoxidase complex catalytically active in organic media.  

PubMed

A surfactant-lactoperoxidase (LPO) complex catalytically active in organic solvents was developed by the emulsion coating method. The oxidation of 2,6-dimethoxyphenol (2,6-DMP) was conducted by the surfactant-LPO complex in organic media. The LPO complex efficiently catalyzed the oxidation of 2,6-DMP in various organic solvents, although lyophilized LPO did not display the catalytic activity at all. To optimize the preparation and reaction conditions for the surfactant-LPO complex, we examined the effects of pH value in the water pools of W/O emulsions, kinds of oxidants, and the nature of organic solvents on the oxidation reaction. Its optimum activity was obtained when the pH value of the aqueous enzyme solution was adjusted to ca. 8 at the preparation stage. The LPO complex exhibited the highest catalytic activity in chloroform when H(2)O(2) was employed as the oxidant. Furthermore, the storage stability of the surfactant-LPO complex was far better than that of the surfactant-horseradish peroxidase complex. This high storage stability of the LPO complex will be a benefit for industrial usage of peroxidases. PMID:10959083

Okazaki; Uchimura; Goto; Furusaki

2000-10-01

310

Removal of pesticides from aqueous solutions using liquid membrane emulsions  

SciTech Connect

Extractive liquid membrane technology is based on a water-in-oil emulsion as the vehicle to effect separation. An aqueous internal reagent phase is emulsified into an organic phase containing a surfactant and optional complexing agents. The emulsion, presenting a large membrane surface area, is then dispersed in an aqueous continuous phase containing the species to be removed. The desired species is transferred from the continuous, phase through the organic liquid membrane and concentrated in the internal reagent phase. Extraction and stripping occur simultaneously rather than sequentially as in conventional solvent extraction. Experiments were conducted to assess the feasibility of using liquid membranes to extract pesticides from rinsewaters typical of those generated by fertilizer/agrichemical dealers. A liquid membrane emulsion containing 10% NaOH as the internal reagent phase was used to extract herbicides from aqueous solution at a continuous phase:emulsion ratio of 5:1. Removals of 2,4-D, MCPA, Carbaryl, Diazinon, and Atrazine were investigated.

Norwood, V.M. III.

1991-01-01

311

Removal of pesticides from aqueous solutions using liquid membrane emulsions  

SciTech Connect

Extractive liquid membrane technology is based on a water-in-oil emulsion as the vehicle to effect separation. An aqueous internal reagent phase is emulsified into an organic phase containing a surfactant and optional complexing agents. The emulsion, presenting a large membrane surface area, is then dispersed in an aqueous continuous phase containing the species to be removed. The desired species is transferred from the continuous, phase through the organic liquid membrane and concentrated in the internal reagent phase. Extraction and stripping occur simultaneously rather than sequentially as in conventional solvent extraction. Experiments were conducted to assess the feasibility of using liquid membranes to extract pesticides from rinsewaters typical of those generated by fertilizer/agrichemical dealers. A liquid membrane emulsion containing 10% NaOH as the internal reagent phase was used to extract herbicides from aqueous solution at a continuous phase:emulsion ratio of 5:1. Removals of 2,4-D, MCPA, Carbaryl, Diazinon, and Atrazine were investigated.

Norwood, V.M. III

1991-12-31

312

Effect of surfactants on co-deposition of B 4C nanoparticles in Zn matrix by electrodeposition and its corrosion behavior  

Microsoft Academic Search

The effect of sodium dodecyl sulfate (SDS) and N,N,N,N cetyltrimethylammonium bromide (CTAB) on co-deposition of B4C nanoparticles with Zn was investigated. The Zn–B4C composite coating was fabricated from solution containing ZnSO4, B4C nanoparticles, and a surfactant. The concentration of surfactants, B4C particles and Zn salts was optimized by Hull cell studies. The cathodic polarization and cyclic voltammograms were recorded for

C. M. Praveen kumar; T. V. Venkatesha; K. G. Chandrappa

313

Evaluation of sucrose esters as alternative surfactants in microencapsulation of proteins by the solvent evaporation method  

Microsoft Academic Search

Sucrose esters (SE) are surfactants with potential pharmaceutical applications because of their low toxicity, biocompatibility,\\u000a and excellent biodegradability. The objective of the study was to investigate SE as alternative surfactants in stabilizing\\u000a emulsions for the preparation of protein-loaded microparticles. To achieve this goal, using bovine serum albumin as model\\u000a protein and 75\\/25 poly(d,1-lactide-co-glycolide) as polymer carrier, we have investigated the

Bi-Botti C. Youan; Alamdar Hussain; Nga T. Nguyen

2003-01-01

314

Multiple emulsion-based systems carrying insulin: development and characterization.  

PubMed

An insulin delivery system based on liquid surfactant membranes has been developed. The formulation was based on a w/o/w emulsion where an organic membrane separated two aqueous phases and the internal aqueous phase contained insulin. Sesame and cotton seed oils were used as organic membranes. In order to facilitate the transportation of glucose across the organic membrane various additives such as calcium stearate, lecithin, cholesterol, hexamine, stearic acid and glyceryl tristearate were used. The additives were found to be successful carriers for the transportation of glucose to the internal aqueous phase. Similarly, viscosity enhancers, e.g. cetostearyl alcohol, in the organic phase enhanced the immobilization of insulin. Various parameters affecting the stability of the emulsions were established. The developed system was characterized for insulin activity and insulin efflux profile. PMID:8558383

Singh, S; Singh, R; Vyas, S P

1995-01-01

315

Amphoteric water-in-oil self-inverting polymer emulsion  

SciTech Connect

An amphoteric water-in-oil self-inverting polymer emulsion is prepared which contains a copolymer of a nonionic vinyl monomer and an amphoteric vinyl monomer or a terpolymer of a nonionic vinyl monomer, an anionic vinyl monomer and a cationic vinyl monomer in the aqueous phase, a hydrocarbon oil for the oil phase, a water-in-oil emulsifying agent and an inverting surfactant. An example of a copolymer is a copolymer of a nonionic vinyl monomer such as acrylamide or methacrylamide and an amphoteric vinyl monomer such as a reaction product of dimethylaminoethyl methacrylate and monochloracetic acid. An example of a terpolymer is a terpolymer of a nonionic vinyl monomer such as acrylamide or methacrylamide, an anionic vinyl monomer such as sodium acrylate and a cationic vinyl monomer such as triethyl ammonium ethyl methacrylate methosulfate salt. The emulsion is useful in papermaking, treatment of sewage and industrial wastes, drilling muds and secondary and tertiary recovery of petroleum by water flooding.

Lipowski, S. A.

1985-11-12

316

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

317

Impact of pNIPAM microgel size on its ability to stabilize Pickering emulsions.  

PubMed

We study the influence of the particle size on the ability of poly(N-isoprolylacrylamide) microgels to stabilize direct oil-in-water Pickering emulsions. The microgel size is varied from 250 to 760 nm, the cross-linking density being kept constant. The emulsion properties strongly depend on the stabilizer size: increasing the particle size induces an evolution from dispersed drops and fluid emulsions toward strongly adhesive drops and flocculated emulsions. In order to get insight into this dependency, we study how particles adsorb at the interface and we determine the extent of their deformation. We propose a correlation between microgel ability to deform and emulsion macroscopic behavior. Indeed, as the microgels size increases, their internal structure becomes more heterogeneous and so does the polymeric interfacial layer they form. The loss of a uniform dense layer favors bridging between neighboring drops, leading to flocculated and therefore less handleable emulsions. PMID:24450736

Destribats, Mathieu; Eyharts, Mayalen; Lapeyre, Véronique; Sellier, Elisabeth; Varga, Imre; Ravaine, Valérie; Schmitt, Véronique

2014-02-25

318

Stabilization of water/gas oil emulsions by desulfurizing cells of Gordonia alkanivorans RIPI90A.  

PubMed

It has been previously reported that resting-cells, non-proliferating cells, of Gordonia alkanivorans RIPI90A can convert dibenzothiophene (DBT) to 2-hydroxybiphenyl (2-HBP) via the 4S pathway in a biphasic system. The main goal of the current work was to study the behaviour of resting-cells of this strain in biphasic organic media. Resting-cells showed strong affinity for sulfurous organic substrates and were able to stabilize water/gas oil emulsions by attaching to the interface without decreasing the surface tension of their environment. This was consistent with the behaviour of the whole cells but not the surfactants, suggesting that microbial cell-mediated emulsification occurs. It was found that the emulsion-stabilizing activity of the resting-cells was influenced by the growth stage, but was not directly influenced by the metabolic activity of the resting-cells. This activity may be related to cell-surface hydrophobicity, which results from the unique chemical structure of the cell surface. In some biphasic biodesulfurization (BDS) bioreactors, emulsions are created without addition of any surfactant. Cell surface-mediated stabilization helps prolong the emulsions and therefore overcomes mass-transfer limitations in bioreactors. The simultaneous occurrence of emulsion-stabilizing and desulfurization activities of resting-cells was observed for what is believed to be the first time. The results suggest that this strain may have potential for the BDS of diesel oils. PMID:17464072

Mohebali, Ghasemali; Ball, Andrew; Kaytash, Ashk; Rasekh, Behnam

2007-05-01

319

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

320

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

2013-07-15

321

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

2013-12-15

322

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

2013-12-01

323

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

2013-07-16

324

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

2013-03-15

325

Effect of volume ratio of internal aqueous phase to organic membrane phase (w\\/o ratio) of water-in-oil emulsion on penicillin G extraction by emulsion liquid membrane  

Microsoft Academic Search

The batch extraction of penicillin G from a model media was studied so as to obtain the optimal w\\/o ratio in an emulsion liquid membrane (ELM) system with the help of our previous works. First of all, the effects of organic solvents or surfactants in membrane phase on apparent degree of its extraction at various w\\/o ratios were investigated. The

Sang Cheol Lee

1999-01-01

326

Migration of Surfactant Vesicles during spontaneous emulsification  

NASA Astrophysics Data System (ADS)

In aqueous AOT solutions, micrometer sized vesicles appear above the critical micelle concentration. These vesicle move spontaneously towards an oil interface and form an emulsion under the condition of ultra low interfacial tension. We discuss the probable mechanisms that lead to the migration behavior of these vesicles.

Michler, Dominik; Shahidzadeh, Noushine; Sprik, Rudolf; Schall, Peter; Bonn, Daniel

2012-02-01

327

Emulsion stabilizing properties of pectin  

Microsoft Academic Search

Citrus pectin and beet pectin are able to reduce the interfacial tension between an oil phase and a water phase and can be efficient for the preparation of emulsions. Investigations were made to evaluate the effect of various parameters of pectin on its emulsifying capacity. Orange and rapeseed oils emulsions were prepared with pectin as an emulsifier. They were then

J. Leroux; V. Langendorff; G. Schick; V. Vaishnav; J. Mazoyer

2003-01-01

328

Preparation of a stable double emulsion (W1/O/W2): role of the interfacial films on the stability of the system.  

PubMed

This paper presents new protocols enabling preparation of W1/O/W2 double emulsions: one, using soybean oil as the O phase, that yields edible emulsions with industrial applications, and a second that yields emulsions with a previously unattainable concentration 15% (w/w) of surfactants in the external phase (the 15% target was chosen to meet the typical industry standard). Preparation of a stable W1/O emulsion was found to be critical for the stability of the system as a whole. Of the various low HLB primary surfactants tested, only cethyl dimethicone copolyol (Abil EM90), A-B-A block copolymer (Arlacel P135), and polyglycerol ester of ricinoleic acid (Grinstead PGR-90) yielded a stable W/O emulsion. Investigation of the surface properties of those surfactants using the monolayer technique found two significant similarities: (1) stable, compressible, and reversibly expandable monolayers; and (2) high elasticity and surface potential. The high degree of elasticity of the interfacial film between W1 and O makes it highly resilient under stress; its failure to break contributes to the stability of the emulsion. The high surface potential values observed suggest that the surfactant molecules lie flat at the O/W interfaces. In particular, in the case of PGR-90, the hydroxyl (-OH) groups on the fatty acid chains serve as anchors at the O/W interfaces and are responsible for the high surface potential. The long-term stability of the double emulsion requires a balance between the Laplace and osmotic pressures (between W1 droplets in O and between W1 droplets and the external aqueous phase W2). The presence of a thickener in the outer phase is necessary in order to reach a viscosity ratio (preferably approximately 1) between the W1/O and W2 phases, allowing dispersion of the viscous primary emulsion into the W2 aqueous phase. The thickener, which also serves as a dispersant and consequently prevents phase separation due to its thixotropic properties, must be compatible with the surfactants. Finally, the interactions between the low and high HLB emulsifiers at the O/W2 interface should not destabilize the films. It was observed that such destructive interaction for the system could be prevented by the use of two high HLB surfactants in the outer aqueous phase: an amphoteric surfactant, Betaine, and an anionic surfactant, sodium lauryl ether sulfate. The combination of such pairs of surfactants was found to contribute to the films' stability. PMID:12509116

Kanouni, M; Rosano, H L; Naouli, N

2002-12-01

329

Status of surfactants as penetration enhancers in transdermal drug delivery  

PubMed Central

Surfactants are found in many existing therapeutic, cosmetic, and agro-chemical preparations. In recent years, surfactants have been employed to enhance the permeation rates of several drugs via transdermal route. The application of transdermal route to a wider range of drugs is limited due to significant barrier to penetration across the skin which is associated with the outermost stratum corneum layer. Surfactants have effects on the permeability characteristics of several biological membranes including skin. They have the potential to solubilize lipids within the stratum corneum. The penetration of the surfactant molecule into the lipid lamellae of the stratum corneum is strongly dependent on the partitioning behavior and solubility of surfactant. Surfactants ranging from hydrophobic agents such as oleic acid to hydrophilic sodium lauryl sulfate have been tested as permeation enhancer to improve drug delivery. This article reviews the status of surfactants as permeation enhancer in transdermal drug delivery of various drugs.

Som, Iti; Bhatia, Kashish; Yasir, Mohd.

2012-01-01

330

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

331

Surfactants and subsurface remediation  

Microsoft Academic Search

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 between the applications, there are significant differences in the objectives of the technologies and the limitations placed on surfactant use. In this article

Candida C. West; Jeffrey H. Harwell

1992-01-01

332

Application of polyhydroxyalkanoate binding protein PhaP as a bio-surfactant.  

PubMed

PhaP or phasin is an amphiphilic protein located on surfaces of microbial storage polyhydroxyalkanoates granules. This study aimed to explore amphiphilic properties of PhaP for possible application as a protein surfactant. Following agents were used to conduct this study as controls including bovine serum albumin, sodium dodecyl sulfate (SDS), Tween 20, sodium oleate, a commercial liquefied detergent together with the same amount of PhaP. Among all these tested control surfactants, PhaP showed the strongest effect to form emulsions with lubricating oil, diesel, and soybean oil, respectively. PhaP emulsion stability study compared with SDS revealed that PhaP had a stronger capability to maintain a very stable emulsion layer after 30 days while SDS lost half and two-thirds of its capacity after 2 and 30 days, respectively. When PhaP was more than 200 ?g/ml in the water, all liquids started to exhibit stable emulsion layers. Similar to SDS, PhaP significantly reduced the water contact angles of water on a hydrophobic film of biaxially oriented polypropylene. PhaP was thermally very stable, it showed ability to form emulsion and to bind to the surface of polyhydroxybutyrate nanoparticles after a 60-?min heating process at 95 °C. It is therefore concluded that PhaP is a protein with thermally stable property for application as natural and environmentally friendly surfactant for food, cosmetic, and pharmaceutical usages. PMID:21590291

Wei, Dai-Xu; Chen, Chong-Bo; Fang, Guo; Li, Shi-Yan; Chen, Guo-Qiang

2011-08-01

333

Fiber coating with surfactant solutions  

NASA Astrophysics Data System (ADS)

When a fiber is withdrawn at low speeds from a pure fluid, the variation in the thickness of the entrained film with imposed fiber velocity is well-predicted by the Landau-Levich-Derjaguin (LLD) equation. However, surfactant additives are known to alter this response. We study the film thickening properties of the protein BSA (bovine serum albumin), the nonionic surfactant Triton X-100, and the anionic surfactant SDS (sodium dodecyl sulfate). For each of these additives, the film thickening factor alpha (the ratio of the measured thickness to the LLD prediction) for a fixed fiber radius varies as a function of the ratio of the surfactant concentration c to the critical micelle concentration (CMC). In the case of BSA, which does not form micelles, the reference value is the concentration at which multilayers form. As a result of Marangoni effects, alpha reaches a maximum as c approaches the CMC from below. However, when the surfactant concentration c exceeds the CMC, the behavior of alpha varies as a consequence of the dynamic surface properties, owing for example to different sorption kinetics of these additives, or possibly surface or bulk rheological effects. For SDS, alpha begins to decrease when c exceeds the CMC and causes the surface to become partially or completely remobilized, which is consistent with the experimental and theoretical results published for studies of slug flows of bubbles and surfactant solutions in a capillary tube and the rise of bubbles in surfactant solutions. However, when the SDS or Triton X-100 surfactant concentration is well above the CMC, we observe that the film thickening parameter alpha increases once again. In the case of SDS we observe a second maximum in the film thickening factor. For all the experiments, transport of monomers to the interface is limited by diffusion and the second maximum in the film thickening factor may be explained as a result of a nonmonotonic change in the stability characteristics of suspended SDS micelles and corresponding changes in the rheology of the solution.

Shen, Amy Q.; Gleason, Blake; McKinley, Gareth H.; Stone, Howard A.

2002-11-01

334

Influence of nonionic branched-chain alkyl glycosides on a model nano-emulsion for drug delivery systems.  

PubMed

The effect of incorporating new nonionic glycolipid surfactants on the properties of a model water/nonionic surfactant/oil nano-emulsion system was investigated using branched-chain alkyl glycosides: 2-hexyldecyl-?(/?)-D-glucoside (2-HDG) and 2-hexyldecyl-?(/?)-D-maltoside (2-HDM), whose structures are closely related to glycero-glycolipids. Both 2-HDG and 2-HDM have an identical hydrophobic chain (C16), but the former consists a monosaccharide glucose head group, in contrast to the latter which has a disaccharide maltose unit. Consequently, their hydrophilic-lipophilic balance (HLB) is different. The results obtained have shown that these branched-chain alkyl glycosides affect differently the stability of the nano-emulsions. Compared to the model nano-emulsion, the presence of 2-HDG reduces the oil droplet size, whereas 2-HDM modify the properties of the model nano-emulsion system in terms of its droplet size and storage time stability at high temperature. These nano-emulsions have been proven capable of encapsulating ketoprofen, showing a fast release of almost 100% in 24h. Thus, both synthetically prepared branched-chain alkyl glycosides with mono- and disaccharide sugar head groups are suitable as nano-emulsion stabilizing agents and as drug delivery systems in the future. PMID:24384142

Ahmad, Noraini; Ramsch, Roland; Llinàs, Meritxell; Solans, Conxita; Hashim, Rauzah; Tajuddin, Hairul Anuar

2014-03-01

335

Effects of Biosurfactant and Emulsification on Two-Liquid Phase Pseudomonas oleovorans Cultures and Cell-Free Emulsions Containing n-Decane  

Microsoft Academic Search

Pseudomonas oleovorans produces significant amounts of surfactants when grown on n-alkanes in two-liquid phase media. We determined the stability and droplet size distribution of emulsions formed by these biosurfactants in cell-free decane-water mixtures at different stirring speeds in a tank reactor. Above 1,500 rpm in the presence of 1 g laq?1 biosurfactant, stable emulsions were formed with Sauter mean droplet

Andrew Schmid; Andreas Kollmer; Bernard Witholt

1998-01-01

336

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

2013-12-01

337

Emulsion-liquid-membrane extraction of copper using a hollow-fiber contactor  

SciTech Connect

A novel extraction technique using an emulsion liquid membrane within a hollow-fiber contactor was developed and utilized to extract copper using LIX 84 extractant. Emulsion liquid membranes are capable of extracting metals from dilute waste streams to levels much below those possible by equilibrium-limited solvent extraction. Utilizing an emulsion liquid membrane within a hollow-fiber contactor retains the advantages of emulsion-liquid-membrane extraction, namely, simultaneous extraction and stripping, while eliminating problems encountered in dispersive contacting methods, such as swelling and leakage of the liquid membrane. Mathematical models for extraction in hollow-fiber contactors were developed. The models satisfactorily predict the outcome of both simple solvent extraction and emulsion-liquid-membrane extraction of copper by LIX 84 in a hollow-fiber contactor over a wide range of conditions. Emulsion-liquid-membrane extraction performs exceptionally well when the extraction is close to equilibrium limit. It is also capable of extracting a solute f/rom very dilute solutions. Stability of the liquid membrane is not crucial when used in hollow-fiber contactors; the surfactant in liquid membrane can be reduced or even eliminated without severely impairing the performance.

Hu, S.Y.B.; Wiencek, J.M. [Univ. of Iowa, Iowa City, IA (United States). Dept. of Chemical and Biochemical Engineering] [Univ. of Iowa, Iowa City, IA (United States). Dept. of Chemical and Biochemical Engineering

1998-03-01

338

Interactions of polyelectrolyte brushes with oppositely charged surfactants  

Microsoft Academic Search

Using Brownian dynamics simulations, we study the effect of the charge ratio, the surfactant length, and the grafting density\\u000a on the conformational behavior of the complex formed by the polyelectrolyte brush with oppositely charged surfactants. In\\u000a our simulations, the polyelectrolyte chains and surfactants are represented by a coarse-grained bead-spring model, and the\\u000a solvent is treated implicitly. It is found that

Qianqian Cao; Chuncheng Zuo; Lujuan Li; Mingfeng Gao

2011-01-01

339

Structural aspects of surfactant selection for the design of vegetable oil semi-synthetic metalworking fluids.  

PubMed

This paper presents a set of surfactant-selection guidelines that can be used to design bio-based semi-synthetic metalworking fluid (MWF) microemulsions as a renewable alternative to conventional petroleum formulations. Ten surfactant classes (six anionic and four nonionic) with different head and tail structures and three vegetable base oils (canola oil, soybean oil, and a fatty acid trimethylolpropane ester) were investigated as representatives of oil and surfactant options currently under consideration in the MWF industry. All combinations of these surfactants and oils were formulated at the full range of oil to surfactant ratios and surfactant concentrations. The stability of each formulation was evaluated based on visual transparency, light transmittance, and droplet diameter. The experimental results yield the following guidelines that produce stable bio-based MWF microemulsions with minimum necessary concentrations of surfactants: (1) a combination of two surfactants, one nonionic and one water soluble co-surfactant (either nonionic or anionic) is preferred over a single surfactant; (2) the nonionic surfactant should have a carbon tail length greater than or equal to the nominal carbon chain length of the fatty acids in the oil as well as a head group that is not excessively small or large (e.g., 10-20 ethylene oxide groups for a polysorbitan ester, ethoxylated alcohol, or ethoxylated glyceryl ester); (3) the difference in tail lengths between the surfactant and the co-surfactant should be less than 6 to maximize the feasible range of oil to surfactant ratios yielding stable emulsions. These guidelines are consistent with general results of micelle solubilization theory and evidence is provided to suggest that common semi-synthetic MWF systems can be thought of as swollen micelle systems. PMID:17256551

Zhao, Fu; Clarens, Andres; Murphree, Ashley; Hayes, Kim; Skerlos, Steven J

2006-12-15

340

Disjoining pressure isotherms of water-in-bitumen emulsion films.  

PubMed

In the oil sands industry, undesirable water-in-oil emulsions are often formed during the bitumen recovery process where water is used to liberate bitumen from sand grains. Nearly all of the water is removed except for a small percentage (approximately 1 to 2%), which remains in the solvent-diluted bitumen as micrometer-sized droplets. Knowledge of the colloidal forces that stabilized these water droplets would help to increase our understanding of how these emulsions are stabilized. In this study, the thin liquid film-pressure balance technique has been used to measure isotherms of disjoining pressure in water/toluene-diluted bitumen/water films at five different toluene-bitumen mass ratios. Even though a broad range of mass ratios was studied, only two isotherms are obtained, indicating a possible change in the molecular orientation of surfactant molecules at the bitumen/water interfaces. At low toluene-bitumen mass ratios, the film stability appears to be due to a strong, short-range steric repulsion created by a surfactant bilayer. Similar isotherms were obtained for water/toluene-diluted asphaltene/water films, indicating that the surface active material at the interface probably originated from the asphaltene fraction of the bitumen. However, unlike the bitumen films, films of toluene-diluted asphaltenes often formed very rigid interfaces similar to the "protective skin" described by other researcher. PMID:16290773

Taylor, Shawn D; Czarnecki, Jan; Masliyah, Jacob

2002-08-01

341

Combustion of drops and sprays of No. 2 diesel oil and its emulsions with water  

SciTech Connect

Experimental results on the combustion of unsupported single drops and pressure-atomized sprays of No. 2D oil and its emulsions with water are presented. The experiments covered the following range of variables: volume fraction of water 0-0.3; surfactant concentration 0-0.05; injection temperature 298-380/sup 0/K; chamber temperature 400-950/sup 0/K; chamber pressure 0.44 to 3.92 MPa; chamber inlet oxygen concentration 0.16-0.75; and spray injector nozzles multihole and pintle. The results show that unsupported droplets of No. 2D diesel oil-water emulsions undergo disruption during combustion, and the fragmentation increases with water content, surfactant content, injection temperature, chamber oxygen concentration, and chamber temperature, but is not significantly dependent on chamber pressure. 18 refs.

Gollahalli, S.R.; Rasmussen, M.L.; Moussavi, S.J.

1981-01-01

342

The Biophysical Function of Pulmonary Surfactant  

PubMed Central

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 three-dimensional 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.

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

2008-01-01

343

Phytosterol colloidal particles as pickering stabilizers for emulsions.  

PubMed

Water-insoluble phytosterols were developed into a kind of colloidal particle as Pickering stabilizers for emulsions by a classic anti-solvent method using 100% ethanol as the organic phase to solubilize the phytosterols and whey protein concentrate (WPC) as the emulsifier. The colloidal particles in the dispersion, with morphology of stacked platelet-like sheets, had a mean diameter of 44.7 and 24.7 ?m for the volume- and surface-averaged sizes, respectively. The properties and stability of the emulsions stabilized by these colloidal particles were highly dependent upon the applied total solid concentration (c; in the dispersion) and oil fraction (ø). The results indicated that (1) at a low c value (<1.0%, w/v) the emulsions were susceptible to phase separation, even at a low ø of 0.2, (2) at low ø values (e.g., 0.2 or 0.3) and a relatively high c value (1.0%, w/v, or above), a severe droplet flocculation occurred for the emulsions, and (3) when both c and ø were appropriately high, a kind of self-supporting gel-like emulsions could be formed. More interestingly, a phase inversion of the emulsions from the oil-in-water to water-in-oil type was observed, upon the ø increasing from 0.2 to 0.6 (especially at high c values, e.g., 3.0%, w/v). The elaborated Pickering emulsions stabilized by the phytosterol colloidal particles with a gel-like behavior would provide a candidate to act as a novel delivery system for active ingredients. PMID:24848560

Liu, Fu; Tang, Chuan-He

2014-06-01

344

Effects of Temperature on the Emulsification in Surfactant-Water-Oil Systems  

NASA Astrophysics Data System (ADS)

The effect of temperature on the emulsification has been investigated by discontinuous molecular dynamic simulation. When a large oil drop is put in water, on one hand the mixing entropy makes it divide into small oil drops; on the other hand the interactions among particles drives the small oil drops fowards aggregation. The evolution of the mean size of oil drops obeys the exponential delay law. There exist an active temperature, at which, the addition of surfactants has obvious effect on the emulsification. The surfactants with low HLB value (e.g. H1T3) make the dispersity of emulsion decrease, and the surfactants with high HLB value (e.g. H2T2 and H3T1) make a contribution to increase the dispersity of emulsion.

Yuan, Yin-Quan; Zou, Xian-Wu; Xiong, Ping-Fan

345

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, Jr., James S. (Oak Ridge, TN); Westmoreland, Clyde G. (Rockwood, TN)

1982-01-01

346

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

347

In vitro studies on release and skin permeation of nonivamide from novel oil-in-oil-emulsions.  

PubMed

The purpose of this study was to develop oil-in-oil-emulsions that facilitate long-term treatment for chronic pruritus with capsaicinoids. To this end, oil-in-oil-emulsions, which comprised polydimethyl siloxanes, silicone surfactant and castor oil, were examined. We used nonivamide, a synthetic analogue of capsaicin as the active pharmaceutical ingredient. It was incorporated into castor oil that formed the dispersed phase of the emulsion. We evaluated the influence of formulation variables (nonivamide content, phase volume ratio and viscosity of the silicone oil) on the in vitro release and the permeation of nonivamide. Permeation was found to be controlled by the nonivamide concentration in the dispersed phase and the phase volume ratio. Oil-in-oil-emulsions were found to produce constant permeation rates over a period of 10h. They are thus superior to conventional semisolid formulations as application intervals may be extended. PMID:24095781

Rottke, Michael; Lunter, Dominique Jasmin; Daniels, Rolf

2014-02-01

348

Conducting polystyrene\\/polyaniline blend through template-assisted emulsion polymerization  

Microsoft Academic Search

Electrically conducting polystyrene (PS)\\/polyaniline blends have been prepared through a one-step “anilinium-surfactant template”-assisted\\u000a emulsion polymerization at room temperature. The self-assembled cylindrical An+PDPSA? micelle formed inside the PS matrix can act as a structure directing template cum dopant. Morphological observation under\\u000a scanning electron microscopic studies revealed that during the progress of polymerization, the initially formed nanostructured\\u000a conducting polyaniline was changed into

J. D. Sudha; S. Sivakala

2009-01-01

349

Mathematical modeling of surface-active and non-surface-active drug transport in emulsion systems  

Microsoft Academic Search

Mathematical models were developed for the prediction of surface-active and non- surface-active drug transport in triphasic\\u000a (oil, water, and micellar) emulsion systems as a function of micellar concentration. These models were evaluated by comparing\\u000a experimental and simulated data. Fick's first law of diffusion with association of the surface-active or complexation nature\\u000a of the drug with the surfactant was used to

Nachiappan Chidambaram; Diane J. Burgess

2000-01-01

350

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.

2005-06-21

351

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

352

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

2012-11-23

353

Lipid transfer between submicrometer sized Pickering ISAsome emulsions and the influence of added hydrogel.  

PubMed

Transfer of lipids between droplets in Pickering emulsions has been studied by time-resolved small-angle X-ray scattering (SAXS). The special features of self-assembled liquid-crystalline phases have been applied to examine the kinetics of internal phase reorganization imposed by lipid release and uptake by the droplets. The findings reveal faster transfer kinetics in Pickering emulsions than in emulsions stabilized with Pluronic F127. It is shown that the transfer kinetics can be accelerated by adding free surfactant to the dispersions and that this acceleration becomes more dominant when micelles are formed. The effect of immobilization of the droplets has been studied by incorporating them into the appropriate hydrogel network. The droplets are arrested, and the transfer slows down significantly at high enough concentrations of the hydrogel where nonergodic systems are obtained. PMID:24559265

Sadeghpour, Amin; Pirolt, Franz; Iglesias, Guillermo Ramón; Glatter, Otto

2014-03-18

354

Controlled release of dual drugs from emulsion electrospun nanofibrous mats.  

PubMed

The purpose of this work is to develop a novel type of tissue engineering scaffold or drugs delivery carrier with the capability of encapsulation and controlled release drugs. In this study, Rhodamine B and Bovine Serum Albumin (BSA) were successfully incorporated into nanofibers by means of emulsion electrospinning. The morphology of composite nanofibers was studied by Scanning Electron Microscopy (SEM). The composite nanofibrous mats made from emulsion electrospinning were characterized by water contact angle measurement and X-ray diffraction. In vitro dual drugs release behaviors from composite nanofibrous mats were investigated. The results indicated that the incorporated drug and/or proteins in composite fibrous mats made from electrospinning could be control released by adjusting the processes of emulsions preparation. PMID:19586756

Yan, Su; Xiaoqiang, Li; Shuiping, Liu; Xiumei, Mo; Ramakrishna, Seeram

2009-10-15

355

Supralinearity in nuclear research emulsions  

Microsoft Academic Search

Nuclear emulsions processed in discriminating developers, intended to suppress small latent image sites, exhibit supralinear sensitometric blackness-exposure curves, whose character varies according to developing time, concentration, and composition, yielding hittedness ranging from 1 to 8, singly and in combination. These emulsion-processing combinations display the phenomena called ion-kill (sensitization by the transit of a single charged particle) and gamma- kill (sensitization

Leif Larsson; F. E. Pinkerton; Robert Katz

1977-01-01

356

Thermocapillary Motion in an Emulsion  

NASA Technical Reports Server (NTRS)

The phenomenological model for the motion of an emulsion or a gas-liquid mixture exposed to thermocapillary forces and micro-acceleration is formulated. The analytical and numerical investigation of one-dimensional flows for these media is fulfilled, the structure of discontinuous motion is studied. The stability conditions of a space-uniform state and of the interface between an emulsion and a pure liquid are obtained.

Pukhnachov, Vladislav V.; Voinov, Oleg V.

1996-01-01

357

Nano-assembly of Surfactants with Interfacial Drug-Interactive Motifs as Tailor-Designed Drug Carriers  

PubMed Central

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-?-tBoc lysine is the most potent, followed by ?-Cbz- and ?-iso-butyloxycarbonyl-?-tBoc-lysine. Using polymer-supported liquid-phase synthesis approach, a series of synthetic lipopeptide surfactants with PEG head group, 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 worm-like micelles. The presence of JP4-039 transformed ?-Fmoc-containing filamentous micelles into dots and bar-like mixed micelles with substantially reduced sizes. Fluorescence quenching and NMR studies revealed that the drug and surfactant molecules were in a 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 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.

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

2012-01-01

358

Silicone oil emulsions stabilized by semi-solid nanostructures entrapped at the interface.  

PubMed

Oil-in-water (O/W) emulsions are typically stabilized using water-soluble surfactants, which anchor to the surface of oil droplets dispersed in an aqueous solution. The structure of the anchored surfactants is often susceptible to physical and chemical stresses because of their highly mobile properties. Here we introduce a new approach to prepare stable silicone oil emulsions under various external stresses using a water-insoluble amphiphilic block copolymer, poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-b-PCL). Above the melting temperature (around 60 degrees C) of the hydrophobic segment (PCL), PEO-b-PCL can be dissolved in silicone oil. When the polymer/oil mixture is dispersed in water, PEO-b-PCL is irreversibly reorganized into solid nanostructures at the interface of the aqueous/organic phases. The resulting interfacial structures provide a robust physical barrier to the emulsion coarsening processes. Accordingly, the prepared emulsions exhibit excellent structural tolerance against external stresses, including variations in pH, ionic strength, and temperature. PMID:20701920

Nam, Yoon Sung; Kim, Jin-Woong; Shim, Jongwon; Han, Sang Hoon; Kim, Han Kon

2010-11-01

359

Studies on the extraction of chromium(III) by emulsion liquid membrane.  

PubMed

This paper presents a comprehensive study on removal of chromium(III) from aqueous waste solution using emulsion liquid membrane (ELM). The study has highlighted the importance of emulsion stability for maximizing the removal of chromium(III). The ELM consists of tri-n-butyl phosphate (TBP) as a carrier, commercial kerosene as organic solvent, sulfonated liquid polybutadiene (LYF) as surfactant agent, sulfuric acid, deionized water or sodium hydroxide as stripping phase. The important factors studied which affected the ELM stability and removal of chromium(III) were the concentrations of surfactant (2-8% w/w), carrier (2-10% w/w), internal phase H(2)SO(4) [pH 0-6], deionized water [pH 6.65] and NaOH (0-0.8% w/w), transfer time (5-35 min) and the effect of volume ratio of the feed solution to the emulsion phase (Rf) (5:1-9:1). At the optimum condition it was possible to remove 99.71-99.83% of chromium(III) by using ELM. LYF was not only the surfactant but also played a key auxiliary effect for TBP combining with chromium(III) by studying on the transport mechanism. PMID:20122791

Zhao, Lifeng; Fei, Dejun; Dang, Yagu; Zhou, Xiaolong; Xiao, Jiali

2010-06-15

360

Synergistic effect of mixed cationic and anionic surfactants on the corrosion inhibitor behavior of mild steel in 3.5% NaCl  

NASA Astrophysics Data System (ADS)

The corrosion inhibition characteristics of cation-rich and anion-rich catanionic mixtures of cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), as corrosion inhibitor of mild steel (MS), in aqueous solution of 3.5% NaCl were investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electron microscopy (SEM). Solutions of CTAB/SDS mixtures showed more appropriate inhibition properties compared to the solutions of the individual surfactants, due to strong adsorption on the metal surface and formation of a protective film. Potentiodynamic polarization investigations indicated that the inhibitors studied were mixed type inhibitors. Adsorption of the inhibitors on the mild steel surface obeyed the Flory-Huggins adsorption isotherm. Furthermore, the values of the adsorption free energy (?G°ads) in both mixtures decreased compared with a single surfactant which is attributed to stronger interactions in mixtures.

Javadian, Soheila; Yousefi, Ali; Neshati, Jaber

2013-11-01

361

Influence of Surfactant Concentration and Counterion to Surfactant Ratio on Rheology of Wormlike Micelles  

Microsoft Academic Search

The influence of concentration on rheological properties, including shear viscosity, shear instability, transient stress start-up and relaxation, apparent extensional viscosity, viscoelastic behavior, and microstructure by cryo-TEM, were studied with surfactant Ethoquad O\\/12, commercialized oleyl methyl bishydroxyethyl chloride, with counterion sodium salicylate. Counterion to surfactant molar ratios, ?, were 1.0 and 2.5. Concentrations for the ?=1 series are 5 mM\\/5 mM,

Zhiqing Lin; Bin Lu; Jacques L. Zakin; Yeshayahu Talmon; Yi Zheng; H. Ted Davis; L. E. Scriven

2001-01-01

362

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

2013-03-01

363

From superhydrophobic to superhydrophilic surfaces tuned by surfactant solutions  

NASA Astrophysics Data System (ADS)

The wettability of hydrophobic surfaces is generally improved by surfactant solutions. The wetting behavior of superhydrophobic surfaces can be classified into two types, in terms of the variation of contact angle with surfactant concentration cs. Contact angle is controlled by surface tension for common linear surfactants and becomes independent of cs as cs>critical micelle concentration. Consequently, superhydrophobic surfaces remain in hydrophobic range, as reported. However, for branch-tailed surfactants such as sodium-bisethylhexylsulfosuccinate and didodecyldimethylammonium bromide, superhydrophobic surfaces can turn superhydrophilic by increasing cs owing to continuous reduction of solid-liquid interfacial tension. The superhydrophobicity is recoverable simply by water rinsing.

Chang, Feng-Ming; Sheng, Yu-Jane; Chen, Hui; Tsao, Heng-Kwong

2007-08-01

364

Clay Modification and Nanocomposite Fabrication with Controlled Polymer/Surfactant  

NASA Astrophysics Data System (ADS)

Recent models of polymer-layered silicate nanocomposite systems indicate that enthalpic and entropic interactions between small molecule clay modifiers (surfactants) and intercalating polymers govern the morphological behavior of these materials. In this work, low polydispersity, polystyrene-based surfactants of specific lengths have been synthesized. Wyoming montmorillonite was subsequently modified via cation exchange with these surfactants in acetonitrile to varying levels of exchange. Polymer-layered silicate nanocomposites were then fabricated using polystyrene homopolymer and the modified montmorillonite to examine the effects of surfactant length, polymer length, and level of exchange on the morphology of the system. The results are then compared with the predictions of the Balazs model.

Beyer, Rick; Tan, Nora Beck; Dasgupta, Arnab; Galvin, Mary

2001-03-01

365

Local geometry of surfactant monolayers in a ternary microemulsion system  

NASA Astrophysics Data System (ADS)

Small angle neutron scattering was used to measure a series of water-octane-C10E4 mixtures in the disordered microemulsion and lamellar phases. Varying the hydrogen-deuterium contrast in oil as well as water enabled us to isolate and determine the scattering contributions from the surfactant monolayers and the water-surfactant and oil-surfactant interfaces. Analyses of the resulting scattering patterns that include the effects of water and oil peneration allow us to demonstrate and quantify the inversion of the surfactant film's small mean curvature as a function of temperature and its relation to the overall phase behavior.

Lee, D. D.; Chen, S. H.

1994-07-01

366

Using the pseudophase kinetic model to interpret chemical reactivity in ionic emulsions: determining antioxidant partition constants and interfacial rate constants.  

PubMed

Kinetic results obtained in cationic and anionic emulsions show for the first time that pseudophase kinetic models give reasonable estimates of the partition constants of reactants, here t-butylhydroquinone (TBHQ) between the oil and interfacial region, P(O)(I), and the water and interfacial region, P(W)(I), and of the interfacial rate constant, k(I), for the reaction with an arenediazonium ion in emulsions containing a 1:1 volume ratio of a medium chain length triglyceride, MCT, and aqueous acid or buffer. The results provide: (a) an explanation for the large difference in pH, >4 pH units, required to run the reaction in CTAB (pH 1.54, added HBr) and SDS (pH 5.71, acetate buffer) emulsions; (b) reasonable estimates of PO(I) and k(I) in the CTAB emulsions; (c) a sensible interpretation of added counterion effects based on ion exchange in SDS emulsions (Na(+)/H3O(+) ion exchange in the interfacial region) and Donnan equilibrium in CTAB emulsions (Br(-) increasing the interfacial H3O(+)); and (d) the significance of the effect of the much greater solubility of TBHQ in MCT versus octane, 1000/1, as the oil. These results should aid in interpreting the effects of ionic surfactants on chemical reactivity in emulsions in general and in selecting the most efficient antioxidant for particular food applications. PMID:23545243

Gu, Qing; Bravo-Díaz, Carlos; Romsted, Laurence S

2013-06-15

367

Solution properties and electrospinning of phosphonium gemini surfactants.  

PubMed

Bis(diphenylphosphino)alkanes quantitatively react with excess 1-bromododecane to prepare novel phosphonium gemini surfactants with spacer lengths ranging from 2 to 4 methylenes (12-2/3/4-12P). Dodecyltriphenylphosphonium bromide (DTPP), a monomeric surfactant analog, was readily water soluble, however, in sharp contrast, phosphonium gemini surfactants were poorly soluble in water due to two hydrophobic tails and relatively hydrophobic cationic head groups containing phenyl substituents. Isothermal titration calorimetry did not reveal a measurable critical micelle concentration for the 12-2-12P phosphonium gemini surfactant in water at 25 °C. Subsequent studies in 50/50 v/v water-methanol at 25 °C showed a CMC of 1.0 mM for 12-2-12P. All phosphonium gemini surfactants effectively complexed nucleic acids, but failed to deliver nucleic acids in vitro to HeLa cells. The solution behavior of phosphonium gemini surfactants was investigated in chloroform, which is an organic solvent where reverse micellar structures are favored. Solution rheology in chloroform explored the solution behavior of the phosphonium gemini surfactants compared to DTPP. The 12-2-12P and 12-3-12P gemini surfactants were successfully electrospun from chloroform to generate uniform fibers while 12-4-12P gemini surfactant and DTPP only electrosprayed to form droplets. PMID:24733359

Hemp, Sean T; Hudson, Amanda G; Allen, Michael H; Pole, Sandeep S; Moore, Robert B; Long, Timothy E

2014-06-14

368

Surfactant phospholipid metabolism  

PubMed Central

Pulmonary surfactant is essential for life and is comprised 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.

Agassandian, Marianna; Mallampalli, Rama K.

2012-01-01

369

Separation Properties of Wastewater Containing O/W Emulsion Using Ceramic Microfiltration/Ultrafiltration (MF/UF) Membranes  

PubMed Central

Washing systems using water soluble detergent are used in electrical and mechanical industries and the wastewater containing O/W emulsion are discharged from these systems. Membrane filtration has large potential for the efficient separation of O/W emulsion for reuses of treated water and detergent. The separation properties of O/W emulsions by cross-flow microfiltration and ultrafiltration were studied with ceramic MF and UF membranes. The effects of pore size; applied pressure; cross-flow velocity; and detergent concentration on rejection of O/W emulsion and flux were systematically studied. At the condition achieving complete separation of O/W emulsion the pressure-independent flux was observed and this flux behavior was explained by gel-polarization model. The O/W emulsion tended to permeate through the membrane at the conditions of larger pore size; higher emulsion concentration; and higher pressure. The O/W emulsion could permeate the membrane pore structure by destruction or deformation. These results imply the stability of O/W emulsion in the gel-layer formed on membrane surface play an important role in the separation properties. The O/W emulsion was concentrated by batch cross-flow concentration filtration and the flux decline during the concentration filtration was explained by the gel- polarization model.

Nakamura, Kazuho; Matsumoto, Kanji

2013-01-01

370

Separation Properties of Wastewater Containing O/W Emulsion Using Ceramic Microfiltration/Ultrafiltration (MF/UF) Membranes.  

PubMed

Washing systems using water soluble detergent are used in electrical and mechanical industries and the wastewater containing O/W emulsion are discharged from these systems. Membrane filtration has large potential for the efficient separation of O/W emulsion for reuses of treated water and detergent. The separation properties of O/W emulsions by cross-flow microfiltration and ultrafiltration were studied with ceramic MF and UF membranes. The effects of pore size; applied pressure; cross-flow velocity; and detergent concentration on rejection of O/W emulsion and flux were systematically studied. At the condition achieving complete separation of O/W emulsion the pressure-independent flux was observed and this flux behavior was explained by gel-polarization model. The O/W emulsion tended to permeate through the membrane at the conditions of larger pore size; higher emulsion concentration; and higher pressure. The O/W emulsion could permeate the membrane pore structure by destruction or deformation. These results imply the stability of O/W emulsion in the gel-layer formed on membrane surface play an important role in the separation properties. The O/W emulsion was concentrated by batch cross-flow concentration filtration and the flux decline during the concentration filtration was explained by the gel- polarization model. PMID:24958621

Nakamura, Kazuho; Matsumoto, Kanji

2013-01-01

371

Evidence for intermittent patterns of fluctuations in particle production in high-energy interactions in nuclear emulsion  

SciTech Connect

The method of scaled factorial moments is used to study short-range fluctuations in the pseudorapidity distributions of particles produced in high-energy interactions in nuclear emulsion. An intermittent behavior of the fluctuations is clearly observed in both proton (200 and 800 GeV) and oxygen (60 and 200 GeV/nucleon) beam interactions in emulsion.

Holynski, R.; Jurak, A.; Olszewski, A.; Wilczynska, B.; Wilczynski, H.; Wolter, W.; Wosiek, B.; Barbier, L.M.; Jones, W.V.; Pruet, O.E.; and others

1989-02-13

372

Effect of water on interfacial chemical properties of nonionic surfactants in hydrophobic ionic liquid bmimPF6.  

PubMed

We studied the effect of water addition on interfacial properties and aggregate behavior of nonionic surfactants (polyoxyethylene alkyl ether; CnEm) in an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate; bmimPF?). When a small amount of water was added to mixtures of CnEm and bmimPF?, two breaking points (cac1, cac2) were observed in the surface tension/CnEm concentration plots, suggesting the formation of two kinds of aggregates. This two-step aggregate formation was also confirmed by the fluorescence probe method using pyrene. The particle size of the aggregates measured by dynamic light scattering (DLS) was around 200 nm at cac1, and decreased to 4 nm above cac2. These results, together with freeze-fracture TEM observations, showed that the aggregate formed at cac1 was water in bmimPF? emulsions, which then transformed to micelles solubilizing water in the palisade layer above cac2. This concentration-dependent aggregate formation was supported thermodynamically by studying the dependence of cacs on temperature and alkyl and POE chain lengths of the surfactant. PMID:23728327

Misono, Takeshi; Aburai, Kenichi; Endo, Takeshi; Sakai, Kenichi; Abe, Masahiko; Sakai, Hideki

2013-01-01

373

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

374

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

375

Lateral phase separation gives multiple lamellar phases in a "binary" surfactant/water system: the phase behavior of sodium alkyl benzene sulfonate/water mixtures.  

PubMed

We have examined the structure of the lamellar phase (Lalpha) that coexists with a micellar solution (L1) for a commercial sodium alkyl benzene sulfonate (LAS) mixed with water. The surfactant is a mixture containing C10-C13 alkyl chains, having all positional isomers of the benzene sulfonate group present except the 1-isomer. Unusually for ionic surfactants, the difference in compositions between the coexisting L1 and Lalpha phases is large (L1 = approximately 20 wt % LAS; Lalpha = approximately 65 wt %). The main technique employed was X-ray diffraction, supplemented by optical microscopy and differential scanning calorimetry (DSC). At ambient temperatures, the lamellar phase gives a single diffraction pattern with the main reflection (d) at approximately 32.5 A, whatever the composition. However, above 40 degrees C, the diffraction peak becomes broader and moves to higher d values. At higher temperatures still, several distinct and different diffraction peaks are observed, differing in detail according to composition. The largest d values (approximately 42-4 A) are observed for the lowest LAS concentrations, while the largest number of separate reflections (five) occurs for samples with approximately 44-50% LAS, both at the highest temperatures. Although there are some differences in the data between heating and cooling cycles, the d values return to the original value at low temperature. There are no observable transitions in DSC, nor is there any heterogeneity in the lamellar phase observable by microscopy. The data clearly indicate that there is some lateral separation of the different LAS isomers within the bilayers, which results in the formation of local lamellar regions having different surfactant compositions. This lateral phase separation may arise from the presence of an (electrostatic) attractive interaction, which gives rise to an upper consolute loop within the lamellar phase region of a pure LAS isomer. Similar mechanisms may occur in biological membranes and could be responsible for the occurrence of membrane lipid patches. PMID:17209595

Richards, Claire; Tiddy, Gordon J T; Casey, Siobhan

2007-01-16

376

Removal of Solid Organic Films from Rotating Disks Using Emulsion Cleaners.  

PubMed

Measurements have been made of the rate of removal of a solid organic film (phenanthrene) from the surface of a rotating disk using emulsions containing water, the nonionic surfactant Tween 20, and d-limonene as the organic phase. The results show that phenanthrene removal initially occurs by the uptake of phenanthrene into the emulsion drops as small aggregates. Simultaneously, the organic phase penetrates into the phenanthrene film, diminishing the adhesive force between the film and the substrate. After sufficient time, the phenanthrene film detaches from the rotating disk surface as a solid. This detachment mechanism accounts for the vast majority of the phenanthrene removal ( approximately 90%). Initial solubilization rates were analyzed using two solubilization models. Both models assume that phenanthrene removal occurs via a mass transfer limited removal of phenanthrene-laden emulsion drops from the phenanthrene film surface into the bulk solution. One model treats the emulsion as homogeneous while the other accounts for the finite size of the emulsion droplets. The latter model was also used to relate the flux of organic phase impacting the phenanthrene film to the detachment times. Copyright 2000 Academic Press. PMID:10926475

Kabin; Withers; Grant; Carbonell; Sáez

2000-08-15

377

Starch nanocrystal stabilized pickering emulsion polymerization for nanocomposites with improved performance.  

PubMed

Latex/starch nanocrystal (SNC) nanocomposite dispersions were successfully synthesized via a one-step surfactant-free Pickering emulsion polymerization route using SNC as the sole stabilizer. The effect of the SNC content, initiator type and comonomer on the particle size, colloidal stability, and film properties were investigated. Both HCl and H2SO4-hydrolysed starch nanocrystals, each bearing different surface charges, were used as Pickering emulsion stabilizing nanoparticles. SNCs from HCl hydrolysis were found to provide a better stabilization effect, giving rise to a polymer dispersion with a lower average particle size. The mechanistic aspects of the Pickering emulsion polymerization were also discussed. Nanocomposites formed by film-casting the polymer Pickering emulsions showed better mechanical properties and optical transparency than those obtained by blending the polymer emulsion with a nanocrystal dispersion, showing the one-pot route to nanocomposite precursors to be doubly advantageous. Therefore, this in situ polymerization technique not only facilitates the use of SNC nanoparticles, it also provides a valuable nanocomposite with enhanced mechanical properties and high transparency level. PMID:24871664

Haaj, Sihem Bel; Thielemans, Wim; Magnin, Albert; Boufi, Sami

2014-06-11

378

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

379

ADSORPTION OF SURFACTANTS  

EPA Science Inventory

Adsorption of surfactants on particles affects their distribution, fate, and effects in natural waters. xperiments were conducted to study the properties of surfactant (charge and structure), solution [H+], [Ca2+], and [Na+]), and sorbent (e.g., organic carbon and cation exchange...

380

Physicochemical studies on the interaction of gelatin with cationic surfactants alkyltrimethylammonium Bromides (ATABs) with special focus on the behavior of the hexadecyl homologue.  

PubMed

The interaction of a denatured interfacially active protein, gelatin (G) (at pH 9, above its isoelectric pH 4.84, and ionic strength mu=0.005), with a cationic amphiphile, hexadecyl (or cetyl) trimethylammonium bromide, CTAB, has been elaborately studied using a variety of techniques. Two types of protein-surfactant complexes at a concentration below the normal critical micellar concentration (cmc) were formed in solution. The first, G-CTAB (monomer) combined complex (GS(n)(I)) adsorbed at the air/solution interface, followed by its gradual transformation to the poor interfacially active second G-CTAB (aggregate) complex (GS(m)(B)) at a critical aggregation concentration (cac) of the interacting oppositely charged surfactant. In the higher concentration range, upon completion of GS(m)(B) formation, coacervation (association of GS(m)(B)) led to add turbidity. With increasing addition of CTAB, the coacervates became disintegrated and ultimately remained dissolved in the free micellar solution of CTAB. The above features were studied using the techniques of tensiometry, conductometry, turbidimetry, fluorimetry, and microcalorimetry. The interaction features were prominent at [G] >or= 0.05 g %, and several of these were either marginal or absent at [G]<0.05 g %. The denatured protein was found to form viscous as well as gel-forming consistencies at higher [G] and at lower temperature. A temperature variation study on the interaction of G with CTAB has revealed that enhanced interaction takes place at higher temperature. The effect of [G] on its interaction with cationic surfactants of varying chain length in the alkyltrimethylammonium bromide (ATAB) series has been also studied; a similar interactional profile as that of CTAB has been exhibited by octadecyltrimethylammonium bromide; however, the lower homologues (dodecyl- and tetradecyl-) of ATAB have offered different profiles. It has been found that the ATABs with higher alkyl chain lengths were more interactive with negatively charged G than their lower homologues. Quantification of the results in terms of different transition points, counterion binding of the protein-bound surfactant aggregates and free micelles, the enthalpy of binding interactions and energetics of ATAB micellization, and so forth have been studied. The results have been rationalized in terms of an interaction model. PMID:18461905

Mitra, Debolina; Bhattacharya, Subhas C; Moulik, Satya P

2008-05-29

381

Emulsion properties of sunflower (Helianthus annuus) proteins.  

PubMed

Emulsions were made with sunflower protein isolate (SI), helianthinin, and sunflower albumins (SFAs). Emulsion formation and stabilization were studied as a function of pH and ionic strength and after heat treatment of the proteins. The emulsions were characterized with respect to average droplet size, surface excess, and the occurrence of coalescence and/or droplet aggregation. Sunflower proteins were shown to form stable emulsions, with the exception of SFAs at neutral and alkaline pH values. Droplet aggregation occurred in emulsions made with SI, helianthinin, and SFAs. Droplet aggregation and subsequent coalescence of emulsions made with SFAs could be prevented at pH 3. Calcium was found to cause droplet aggregation of emulsions made with helianthinin, at neutral and alkaline pH values. Treatments that increase conformational flexibility of the protein molecule improved the emulsion properties of sunflower proteins. PMID:15769166

González-Pérez, Sergio; van Konigsveld, Gerrit A; Vereijken, Johan M; Merck, Karin B; Gruppen, Harry; Voragen, Alphons G J

2005-03-23

382

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

383

[Genetic disorders of surfactant].  

PubMed

Lung diseases associated with surfactant metabolism disorders represent a significant but heterogeneous group of rare disorders. Intra-alveolar accumulation of protein related to surfactant dysfunction leads to cough, hypoxemia and radiological diffuse infiltration. Inherited deficiency of pulmonary surfactant protein B (SP-B) was initially described in term newborns who develop severe respiratory failure at birth. More recently, mutations in surfactant protein C (SP-C) or in proteins required for surfactant synthesis such as ATP-binding cassette, sub-family A, member 3 (ABCA3) or NK2 homeobox 1 (NKX2-1) were identified in newborns with respiratory distress but also in children with diffuse infiltrative pneumonia. The aim of this review is to describe the clinical presentation of these diseases but also the diagnostic tools and the treatments options available. PMID:22236549

Epaud, R; Jonard, L; Ducou-le-Pointe, H; Delestrain, C; Fanen, P; Guillot, L; Flamein, F

2012-02-01

384

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

385

Transfer of Oil between Emulsion Droplets  

Microsoft Academic Search

A contrast matching technique was used to determine the exchange of oils between emulsion droplets having different refractive indexes. Emulsions of tetradecane and 1-bromo tetradecane in water were made separately in a high-pressure homogenizer, then mixed and equilibrated at rest. It was found that droplets exchanged oil molecules through the continuous phase, in a process similar to Ostwald ripening. Emulsions

Laurent Taisne; Pieter Walstra; Bernard Cabane

1996-01-01

386

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

387

A real-time impedance-sensing chip for the detection of emulsion phase separation.  

PubMed

This paper describes a novel real-time impedance chip for the detection of squalene-water emulsion phase separation. Each impedance chip contains eight pairs of indium tin oxide microelectrode arrays for detecting eight samples, and six chips can be connected with the switch relay to measure 48 samples in the system simultaneously. The proposed impedance chip has the advantages of needing only a small sample volume (0.5 mL), and provides parallel, continuous, and real-time detection. The effects of the surfactant concentration on the stability of a squalene/water emulsion were studied by means of a visual inspection, a conductance probe, and by impedance chip. Three different concentrations of Tween 20 surfactant (9, 17, and 29 wt%) were employed for the examinations. The results indicated that the phase separation rate was faster in the lower surfactant concentration. However, the emulsion of 29 wt% Tween 20 was fairly stable for more than 2 days since there were no signal changes according to the three detection methods. The reaction time (TR) for completing the measured phase separation process differed for each of the three methods (measuring aqueous phase height, conductance, and impedance, respectively). For the 9 wt% Tween 20, the reaction times were 24 h, 20 min, and 5 min in the tests using visual inspection, conductance probe, and impedance chip, respectively. For the 17 wt% Tween 20, the TR was also shorter when using the impedance chip method compared to the other two methods. Therefore the proposed impedance chip has a quick reaction response and provides an alternative and effective method to detect emulsion stability. PMID:23765861

Lin, Yung-Sheng; Chou, Wei-Lung; Yang, Chih-Hui; Huang, Keng-Shiang; Wang, Eng-Chi; Chen, Cheng-You; Lin, Yu-Hsin; Huang, Haw-Ming

2013-06-01

388

Polymer Blend Emulsions Stabilized by Janus Particles  

NASA Astrophysics Data System (ADS)

Kinetic trapping of bicontinuous polymer morphologies through the interfacial segregation of nanoparticles is of interest due to the unique combination of the properties of each component provided by such structures, and their potential for use as membranes and composite materials. However, this strategy is challenging to realize in polymeric systems, due to the difficulties in preparing particles that are neutrally wetted by the two polymer phases. Janus particles afford a route to circumvent the necessity of neutral wettability. In addition, both theory and experiment have shown enhanced interfacial adsorption energies for Janus particles, as well as greater flexibility in controlling particle orientation at the interface, in comparison to homogeneous particles. Dumbbell-shaped gold-silica Janus particles were synthesized using several sizes of gold seeds. These particles were made amphiphilic by functionalization with both polymeric and small molecule silanes and thiols. Their interfacial activity was measured using pendant drop tensiometry, and their ability to stabilize bicontinuous emulsions of polymers was examined by TEM. The results elucidate the role of particle wettability on interfacial behavior and the structure of stabilized emulsions.

Bryson, Kyle; Russell, Thomas; Hayward, Ryan

2013-03-01

389

Advances in Intravenous Lipid Emulsions  

Microsoft Academic Search

Over the past decade, our views have\\u000a considerably evolved with respect to the metabolism of intravenous\\u000a lipid emulsions and their composition. Substantial progress has been\\u000a made in understanding the metabolic pathways of emulsion particles and\\u000a the delivery of their various components (fatty acids and vitamins) to\\u000a specific tissues or cells. Although soybean long-chain triglycerides\\u000a represent a valuable source of energy,

2000-01-01

390

Interfacial and colloidal properties of cosmetic emulsions containing fatty alcohol and fatty alcohol polyglycol ethers  

Microsoft Academic Search

The phase behavior of multicomponent systems, especially of emulsions containing cetostearyl alcohol and fatty alcohol polyglycol\\u000a ethers has been investigated. At the phase inversion from o\\/w to w\\/o emulsions, one-phase regions containing lamellar liquid\\u000a crystals have been observed. In appropriate ratios of the amphiphiles, extremely low interfacial tensions (?10?3 mN\\/m) are obtained, which lead to very easy emulsification and narrow

F. Schambil; F. Jost; M. J. Schwuger

391

Interfacial Properties of Surfactant Monolayers in Microemulsion Systems.  

NASA Astrophysics Data System (ADS)

Surfactants in solution can spontaneously self -assemble to form interfacial monolayers which separate mesoscopic regions of water and oil. The statistical mechanics of the surfactant monolayers can explain the rich phase behavior and novel physical properties of microemulsion systems. Here we use x-ray reflectivity to study the intrinsic properties of a single surfactant monolayer at an oil-water interface in equilibrium with a middle-phase microemulsion. We find that the fluctuations of the monolayer are described by large capillary waves due to the small interfacial tension and bending rigidity of the surfactant interface. Next we measure the local geometry of the surfactant monolayers within a bicontinuous microemulsion using isotopic contrast variation and small angle neutron scattering. The mean curvature of the surfactant film is very small and inverts as a function of temperature. We also use neutron reflectivity to relate the surface correlations of the surfactant monolayers near a solid interface to the bulk correlations in the microemulsion. A Ginzburg-Landau theory is employed to interpret our results and to provide further insight into explaining the behavior of the surfactant monolayers in these complex liquids. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).

Lee, Daniel Dongyuel

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

Synthesis and purification of oxide nanoparticle dispersions by modified emulsion precipitation.  

PubMed

ZrO2 and Fe2O3 precursor nanoparticles are synthesized, well-dispersed in decane, via a modified emulsion precipitation (MEP) method. This method starts with preparing two thermostable water-in-oil (w/o) emulsions with nonylphenol tetra(ethylene glycol) ether (Arkopal-40) as the main surfactant, didodecyldimethylammonium bromide (DiDAB) as the cosurfactant, decane as the continuous oil phase, and either a metal salt solution or a hexamethylenetetramine (HMTA) precipitation agent solution as the dispersed water phase. After mixing of the two emulsions, individual precursor particles are formed by precipitation in the confinement of the aqueous solution droplets. Excess water is removed by azeotropic distillation, and steric stabilization of the particles in the remaining oil medium is achieved with poly(octadecyl methacrylate) (PODMA), initially present dissolved in the oil phase. A purification process is conducted to remove the precipitation reaction byproduct and excess surfactants from the nanoparticle dispersions. Transmission electron microscopy (TEM) characterization shows that the ZrO2 and Fe2O3 precursor nanoparticles are both non-agglomerated, spherical, and have a narrow particle size distribution, centered at 4 nm in diameter. The precipitation from the dispersion of byproduct NH4Cl after water removal, and insoluble surfactant DiDAB after dilution with pure decane, is confirmed by X-ray diffraction (XRD). NMR results show that most of the oil-soluble surfactant Arkopal-40 can be removed from the dispersion by a 3x repeated dead-end pressure filtration process. It is shown that, after purification, the nanoparticle dispersions can be used for the preparation of homogeneous nanostructured coatings. The purification procedure as discussed provides guidelines for up-scaling the process and reuse of emulsifiers. PMID:15924491

Shi, Jingyu; Verweij, Henk

2005-06-01

394

Emulsion Droplet Combustion in Microgravity: Water/Heptane Emulsions  

NASA Technical Reports Server (NTRS)

This presentation reviews a series of experiments to further examine parametric effects on sooting processes of droplet flames in microgravity. The particular focus is on a fuel droplet emulsified with water, specifically emulsions of n-heptane as the fuel-phase and water as the dispersed phase. Water was selected as the additive because of its anticipated effect on soot formation, and the heptane fuel phase was chosen to theoretically reduce the likelihood of microexplosions because its boiling point is nearly the same as that of water: 100 C for water and 98 C for heptane. The water content was varied while the initial droplet diameter was kept within a small range. The experiments were carried out in microgravity to reduce the effects of buoyancy and to promote spherical symmetry in the burning process. Spherically symmetric droplet burning is a convenient starting point for analysis, but experimental data are difficult to obtain for this situation as evidenced by the fact that no quantitative data have been reported on unsupported emulsion droplet combustion in a convection-free environment. The present study improves upon past work carried out on emulsion droplet combustion in microgravity which employed emulsion droplets suspended from a fiber. The fiber can be instrusive to the emulsion droplet burning process as it can promote coalescence of the dispersed water phase and heterogeneous nucleation on the fiber. Prior work has shown that the presence of water in liquid hydrocarbons can have both beneficial and detrimental effects on the combustion process. Water is known to reduce soot formation and radiation heat transfer to combustor walls Gollahalli (1979) reduce flame temperatures and thereby NOx emissions, and encourage secondary droplet atomization or microexplosion. Water also tends to retard ignition and and promote early extinction. The former effect restricted the range of water volume fractions as discussed below.

Avedisian, C. Thomas

1997-01-01

395

Solid-state nanoparticle coated emulsions for encapsulation and improving the chemical stability of all-trans-retinol.  

PubMed

Submicron oil-in-water (o/w) emulsions stabilised with conventional surfactants and silica nanoparticles were prepared and freeze-dried to obtain free-flowing powders with good redispersibility and a three-dimensional porous matrix structure. Solid-state emulsions were characterised for visual appearance, particle size distribution, zeta potential and reconstitution properties after freeze-drying with various sugars and at a range of sugar to oil ratios. Comparative degradation kinetics of all-trans-retinol from freeze-dried and liquid emulsions was investigated as a function of storage temperatures. Optimum stability was observed for silica-coated oleylamine emulsions at 4 °C in their wet state. The half-life of all-trans-retinol was 25.66 and 22.08 weeks for silica incorporation from the oil and water phases respectively. This was ?4 times higher compared to the equivalent solid-state emulsions with drug half-life of 6.18 and 6.06 weeks at 4 °C. Exceptionally, at a storage temperature of 40 °C, the chemical stability of the drug was 3 times higher in the solid-state compared to the wet emulsions which confirmed that freeze-drying is a promising approach to improve the chemical stability of water-labile compounds provided that the storage conditions are optimised. PMID:22210001

Ghouchi-Eskandar, Nasrin; Simovic, Spomenka; Prestidge, Clive A

2012-02-28

396

Emulsion Chamber Technology Experiment (ECT)  

NASA Technical Reports Server (NTRS)

The experimental objective of Emulsion Chamber Technology (ECT) was to develop space-borne emulsion chamber technology so that cosmic rays and nuclear interactions may subsequently be studied at extremely high energies with long exposures in space. A small emulsion chamber was built and flown on flight STS-62 of the Columbia in March 1994. Analysis of the several hundred layers of radiation-sensitive material has shown excellent post-flight condition and suitability for cosmic ray physics analysis at much longer exposures. Temperature control of the stack was 20 +/-1 C throughout the active control period and no significant deviations of temperature or pressure in the chamber were observed over the entire mission operations period. The unfortunate flight attitude of the orbiter (almost 90% Earth viewing) prevented any significant number of heavy particles (Z greater than or equal to 10) reaching the stack and the inverted flow of shower particles in the calorimeter has not allowed evaluation of absolute primary cosmic ray-detection efficiency nor of the practical time limits of useful exposure of these calorimeters in space to the level of detail originally planned. Nevertheless, analysis of the observed backgrounds and quality of the processed photographic and plastic materials after the flight show that productive exposures of emulsion chambers are feasible in low orbit for periods of up to one year or longer. The engineering approaches taken in the ECT program were proven effective and no major environmental obstacles to prolonged flight are evident.

Gregory, John C.; Takahashi, Yoshiyuki

1996-01-01

397

Lipid oxidation in food emulsions  

Microsoft Academic Search

Lipid oxidation is a major cause of quality deterioration in food emulsions. The design of foods with improved quality depends on a better understanding of the physicochemical mechanisms of lipid oxidation in these systems. The oxidation of emulsified lipids differs from that of bulk lipids, because of the presence of the droplet membrane, the interactions between the ingredients, and the

John N. Coupland; D. Julian McClements

1996-01-01

398

Electrochromism in switchable nematic emulsions  

Microsoft Academic Search

Switchable nematic emulsions are composite systems formed by liquid-crystal droplets dispersed in a fluid, homogeneous, monomer matrix, which can be turned from an opaque to an optically transparent state by application of a suitable ac electric field. An electrochromic device provides a reversible and visible change in its transmittance and\\/or reflectance as the result of either oxidation or reduction electrochemical

F. P. Nicoletta; D. Cupelli; G. de Filpo; G. Chidichimo

2004-01-01

399

Self-Assembly of Gemini Surfactants  

NASA Astrophysics Data System (ADS)

The self-assembly behavior of Gemini (dimeric or twin-tail) dicarboxylate disodium surfactants is studied using molecular dynamics simulations. This gemini architecture, in which two single tailed surfactants are joined through a flexible hydrophobic linker, has been shown to exhibit concentration-dependent aqueous self-assembly into lyotropic phases including hexagonal, gyroid, and lamellar morphologies. Our simulations reproduce the experimentally observed phases at similar amphiphile concentrations in water, including the unusual ability of these surfactants to form gyroid phases over unprecedentedly large amphiphile concentration windows. We demonstrate quanitative agreement between the predicted and experimentally observed domain spacings of these nanostructured materials. Through careful conformation analyses of the surfactant molecules, we show that the gyroid phase is electrostatically stabilized related to the lamellar phase. By starting with a lamellar phase, we show that decreasing the charge on the surfactant headgroups by carboxylate protonation or use of a bulkier tetramethyl ammonium counterion in place of sodium drives the formation of a gyroid phase.

Yethiraj, Arun; Mondal, Jagannath; Mahanthappa, Mahesh

2013-03-01

400

Waterflooding employing amphoteric surfactants  

SciTech Connect

Process for the recovery of oil from a subterranean oil reservoir involving the injection into the reservoir of an aqueous solution of an amphoteric surfactant having an inner quaternary ammonium group linked to a terminal sulfonate or carboxylate group is described. The amphoteric surfactants may be employed in relatively low concentrations within the range of 0.0005 to 0.1% by weight and injected in a slug of at least 0.5 pv. The apparatus may be applied in situations in which the reservoir waters and/or the waters employed in formulating the surfactant solution contain relatively high amounts of divalent metal ions. Specifically described amphoteric surfactants include hydrocarby dialkyl or dihydroxyalkyl ammonium alkane sulfonates and carboxylates in which the hydrocarbyl group contains from 8 to 26 carbon atoms. 29 claims.

Stournas, S.

1980-08-05

401

Production of W/O/W (water-in-oil-in-water) multiple emulsions: droplet breakup and release of water.  

PubMed

We investigate breakup of W/O/W double emulsion droplets at high viscosity ratios and coalescence of inner water droplets dependent on the dispersed phase content (DPC) of the inner emulsion. The rheological analyses of the inner emulsions confirm the behavior expected from literature - increasing viscosity with increasing DPC and elastic behavior for high DPC. The resulting droplet sizes seem to be influenced only by the viscosity ratio calculated using the viscosity of the inner emulsion. An influence of the elastic properties of the inner emulsions could not be observed. Moreover, breakup of double emulsion droplets seems to follow the same rules as breakup of Newtonian droplets. In the second part of the paper we focus on the release of water from double emulsions by coalescence. A direct correlation between resulting double emulsion droplet sizes and encapsulation efficiency was found for each system. The initial inner dispersed phase content has a big influence on the release rate. This can partly be explained by the influence of the dispersed phase content on collision rate. Moreover, it was found that for high internal phase concentrations inner droplets coalesce with each other. The so formed bigger inner droplets seem to increase the overall release rate. PMID:23643254

Schuch, Anna; Deiters, Philipp; Henne, Julius; Köhler, Karsten; Schuchmann, Heike P

2013-07-15

402

Structure Formation in Micro-Confined Polymeric Emulsions  

NSDL National Science Digital Library

In the present work, we present results of concentrated solutions under shear, with particular emphasis on the case that the emulsion is microconfined. When the size of a typical droplet is comparable to the gap width between the shearing plates, we observe interesting non-equilibrium pattern formation of the collective behavior. We present three results in which spontaneous structures emerge in the system; string formation, the pearl necklace structure and droplet layering.

Pathak, J. A.; Hudson, S. D.; Migler, K. B.

2002-01-01

403

Normal Surfactant Pool Sizes and Inhibition-Resistant Surfactant from Mice That Overexpress Surfactant Protein A  

Microsoft Academic Search

Pulmonary surfactant protein-A (SP-A) has been reported to regulate the uptake and secretion of surfactant by alveolar type II cells, to stabilize large surfactant aggregates including tubular myelin, and to protect the surface activity of surfactant from protein inhibitors. In this study we investigated the consequences of overexpression of SP-A on pulmonary homeostasis and surfactant function in transgenic mice. The

Baher M. Elhalwagi; Mei Zhang; Machiko Ikegami; Harriet S. Iwamoto; Randall E. Morris; Marian L. Miller; Krista Dienger; Francis X. McCormack

1999-01-01

404

Aqueous Gemini Surfactant Self-Assembly into Complex Lyotropic Phases  

NASA Astrophysics Data System (ADS)

In spite of the potentially wide-ranging applications of aqueous bicontinuous lyotropic liquid crystals (LLCs), the discovery of amphiphiles that reliably form these non-constant mean curvature morphologies over large phase windows remains largely serendipitous. Recent work has established that cationic gemini surfactants exhibit a pronounced tendency to form bicontinuous cubic (e.g. gyroid) phases as compared to their parent single-tail amphiphiles. The universality of this phenomenon in other surfactant systems remains untested. In this paper, we will report the aqueous LLC phase behavior of a new class of anionic gemini surfactants derived from long chain carboxylic acids. Our studies show that these new surfactants favor the formation of non-constant mean curvature gyroid and primitive (``Plumber's Nightmare'') structures over amphiphile concentration windows up to 20 wt% wide. Based on these observations, we will discuss insights gained into the delicate force balance governing the self-assembly of these surfactants into aqueous bicontinuous LLCs.

Mahanthappa, Mahesh; Sorenson, Gregory

2012-02-01

405

Amphoteric water-in-oil self-inverting polymer emulsion  

SciTech Connect

An amphoteric water-in-oil self-inverting polymer emulsion is prepared which contains a copolymer of a nonionic vinyl monomer and an amphoteric vinyl monomer or a terpolymer of (1) a nonionic vinyl monomer, an anionic vinyl monomer and a cationic vinyl monomer in the aqueous phase, a hydrocarbon oil for the oil phase, a water-in-oil emulsifying agent and an inverting surfactant. An example of a copolymer is a copolymer of a nonionic vinyl monomer such as acrylamide or methacrylamide and an amphoteric vinyl monomer such as a reaction product of dimethylaminoethyl methacrylate and monochloroacetic acid. An example of a terpolymer is a terpolymer of a nonionic vinyl monomer such as acrylamide or methacrylamide, an anionic vinyl monomer such as sodium acrylate and a cationic vinyl monomer such as a triethyl ammonium ethyl methacrylate methosulfate salt. The emulsion is useful in papermaking, treatment of sewage and industrial wastes, drilling muds and secondary and tertiary recovery of petroleum by water flooding.

Lipowski, S. A.; Miskel Jr., J. J.

1985-03-19

406

Use of acyl phosphonates for the synthesis of inulin esters and their use as emulsion stabilizing agents.  

PubMed

Inulin, the polydisperse polyfructose, extracted from chicory, was modified via esterification with acyl phosphonates. The grafting of an acyl chain onto the inulin backbone under different conditions led to a highly efficient synthesis of a series of inulin esters, with interesting tensioactive properties. The derivatives were evaluated in oil-in-water (O/W) emulsions with isoparaffinic oil, Isopar M. Therefore, a 2% (w/v) aqueous solution of inulin-based surfactant was used in 50/50 O/W emulsions, in nonelectrolyte, and in electrolyte media, using 1 M MgSO4. Longer acyl chains, e.g., dodecanoyl (C12), hexadecanoyl (C16), and octadecanoyl (C18), with degrees of substitution lower than 0.5, gave rise to the highest emulsion stabilities against coalescence. PMID:17291072

Rogge, Tina M; Stevens, Christian V; Colpaert, Anton; Levecke, Bart; Booten, Karl

2007-02-01