Sample records for emulsion behavior surfactant

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

    SciTech Connect

    LEBONE MOETI; RAMANATHAN SAMPATH

    1998-11-01

    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.

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

    SciTech Connect

    Lebone T. Moeti; Ramanathan Sampath

    2001-09-28

    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.

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

    SciTech Connect

    Moeti, Lebone T.; Sampath, Ramanathan

    2002-03-13

    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.

  4. Surfactant-enhanced cellulose nanocrystal Pickering emulsions.

    PubMed

    Hu, Zhen; Ballinger, Sarah; Pelton, Robert; Cranston, Emily D

    2015-02-01

    The effect of surfactants on the properties of Pickering emulsions stabilized by cellulose nanocrystals (CNCs) was investigated. Electrophoretic mobility, interfacial tension, confocal microscopy and three-phase contact angle measurements were used to elucidate the interactions between anionic CNCs and cationic alkyl ammonium surfactants didecyldimethylammonium bromide (DMAB) and cetyltrimethylammonium bromide (CTAB). Both surfactants were found to adsorb onto CNCs with concentration-dependent morphology. At low concentrations, individual surfactant molecules adsorbed with alkyl tails pointing outward leading to hydrophobic CNCs. At higher concentrations, above the surfactant's apparent critical micelle concentration, surfactant aggregate morphologies on CNCs were inferred and the hydrophobicity of CNCs decreased. DMAB, which has two alkyl tails, rendered the CNCs more hydrophobic than CTAB which has only a single alkyl tail, at all surfactant concentrations. The change in CNC wettability from surfactant adsorption was directly linked to emulsion properties; adding surfactant increased the emulsion stability, decreased the droplet size, and controlled the internal phase of CNC Pickering emulsions. More specifically, a double transitional phase inversion, from oil-in-water to water-in-oil and back to oil-in-water, was observed for emulsions with CNCs and increasing amounts of DMAB (the more hydrophobic surfactant). With CNCs and CTAB, no phase inversion was induced. This work represents the first report of CNC Pickering emulsions with surfactants as well as the first CNC Pickering emulsions that can be phase inverted. The ability to surface modify CNCs in situ and tailor emulsions by adding surfactants may extend the potential of CNCs to new liquid formulations and extruded/spray-dried materials. PMID:25463186

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

    SciTech Connect

    Ramanathan Sampath

    2004-09-30

    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.

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

    SciTech Connect

    Ramanathan Sampath

    2003-10-01

    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.

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

    SciTech Connect

    Ramanathan Sampath

    2004-03-31

    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.

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

    SciTech Connect

    Ramanathan Sampath

    2003-03-31

    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.

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

    SciTech Connect

    Ramanathan Sampath

    2005-12-01

    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.

  10. Feasibility of Surfactant-Free Supported Emulsion Liquid Membrane Extraction

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

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

    SciTech Connect

    Ramanathan Sampath

    2005-09-30

    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.

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

    SciTech Connect

    Ramanathan Sampath

    2005-03-31

    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.

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

    Microsoft Academic Search

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

    2010-01-01

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

  14. Crude oil emulsions containing a compatible fluorochemical surfactant

    SciTech Connect

    Karydas, A.; Rodgers, J.

    1991-02-19

    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.

  15. Principles of emulsion stabilization with special reference to polymeric surfactants.

    PubMed

    Tadros, Tharwat

    2006-01-01

    This overview summarizes the basic principles of emulsion stabilization with particular reference to polymeric surfactants. The main breakdown processes in emulsions are briefly described. A section is devoted to the structure of polymeric surfactants and their conformation at the interface. Particular attention is given to two polymeric surfactants that are suitable for oil-in-water (O/W) and water-in-oil (W/O) emulsions. For O/W emulsions, a hydrophobically modified inulin (HMI), obtained by grafting several alkyl groups on the backbone of the inulin (polyfructose) chain, is the most suitable. For W/O emulsions, an A-B-A block copolymer of polydroxystearic acid (PHS), the A chains, and polyethylene oxide (PEO), the B chain, is the most suitable. The conformation of both polymeric surfactants at the O/W and W/O interfaces is described. A section is devoted to the interaction between emulsion droplets containing adsorbed polymer surfactant molecules. This interaction is referred to as steric stabilization, and it is a combination of two main effects, namely, unfavorable mixing of the A chains, referred to as the mixing interaction, Gmix, and loss of configurational entropy on significant overlap of the stabilizing chains, referred to as elastic interaction, Gel. The criteria for effective steric stabilization are summarized. O/W emulsions based on HMI are described, and their stability in water and in aqueous electrolyte solutions is investigated using optical microscopy. Very stable emulsions can be produced both at room temperature and at 50 degrees C. The reason for this high stability is described in terms of the multipoint anchoring of the polymeric surfactant (by several alkyl groups), the strong hydration of the inulin (polyfructose) chains, and the high concentration of inulin in the adsorbed layer. W/O emulsions using PHS-PEO-PHS block copolymer can be prepared at a high volume fraction of water, varphi, and these emulsions remain fluid up to high varphi values (> 0.6). These emulsions also remain stable for several months at room temperature and at 50 degrees C. The last two sections are concerned with the problems of creaming or sedimentation and phase inversion. Creaming or sedimentation can be prevented by the use of "thickeners" in the continuous phase. These molecules produce non-Newtonian systems that will have a high residual or zero shear viscosity. The latter, which may exceed 1000 Pas, can also be prevented by control of the bulk (or elastic) modulus of the system. Phase inversion in O/W emulsions can also be prevented using HMI, since this polymeric surfactant is not soluble in the oil phase. As long as coalescence and Ostwald ripening are prevented, the emulsions can remain stable for very long times both at room temperature and at 50 degrees C. PMID:16688378

  16. Photoinduced demulsification of emulsions using a photoresponsive gemini surfactant.

    PubMed

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

    2014-01-14

    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

  17. The temperature stability of single and mixed emulsions stabilized by nonionic surfactants

    Microsoft Academic Search

    Phillip J. Dale; Johan Kijlstra; Brian Vincent

    2006-01-01

    Reasonably monodisperse (vegetable) oil-in-water emulsions have been prepared with three different non-ionic surfactants, each of having the same hydrophobic tail group, but with poly(ethylene oxide) (PEO) head groups containing 18, 27 or 48 monomer units. A set of three emulsions, containing similar sized oil droplets (?400nm diameter), has been prepared using these three surfactants. In addition, an emulsion with 200nm

  18. Effects of surfactant structure on the phase inversion of emulsions stabilized by mixtures of silica nanoparticles and cationic surfactant.

    PubMed

    Cui, Z-G; Yang, L-L; Cui, Y-Z; Binks, B P

    2010-04-01

    Silica nanoparticles without any surface modification are not surface active at the toluene-water interface due to their extreme hydrophilicity but can be surface activated in situ by adsorbing cationic surfactant from water. This work investigates the effects of the molecular structure of water-soluble cationic surfactant on the surface activation of the nanoparticles by emulsion characterization, adsorption and zeta potential measurements, dispersion stability experiments, and determination of relevant contact angles. The results show that an adsorbed cationic surfactant monolayer on particle surfaces is responsible for the wettability modification of the particles. In the presence of a trace amount of cationic surfactant, the hydrophobicity of the particles increases, leading to the formation of stable oil-in-water O/W(1) emulsions. At high surfactant concentration (>cmc) the particle surface is retransformed to hydrophilic due to double-layer or hemimicelle formation, and the concentration of the free surfactant in the aqueous phase is high enough to stabilize emulsions alone. O/W(2) emulsions, probably costabilized by free surfactant and particles, are then formed. The monolayer adsorption seems to be charge-site dependent. Thus, using single-chain trimethylammonium bromide surfactants or a double-head gemini cationic surfactant, the hydrophobicity of the particles achieved is not sufficient to stabilize water-in-oil (W/O) emulsions, and no phase inversion is induced. However, using a double-chain cationic surfactant, the chain density on the particle surfaces endows them with a hydrophobicity high enough to stabilize W/O emulsions, and double phase inversion, O/W(1) --> W/O --> O/W(2), can then be achieved by increasing the surfactant concentration. PMID:19950938

  19. Synergistic stabilization of emulsions by a mixture of surface-active nanoparticles and surfactant.

    PubMed

    Binks, Bernard P; Desforges, Alexandre; Duff, Daniel G

    2007-01-30

    The stability and rheology of tricaprylin oil-in-water emulsions containing a mixture of surface-active hydrophilic silica nanoparticles and pure nonionic surfactant molecules are reported and compared with those of emulsions stabilized by each emulsifier alone. The importance of the preparation protocol is highlighted. Addition of particles to a surfactant-stabilized emulsion results in the appearance of a small population of large drops due to coalescence, possibly by bridging of adsorbed particles. Addition of surfactant to a particle-stabilized emulsion surprisingly led to increased coalescence too, although the resistance to creaming increased mainly due to an increase in viscosity. Simultaneous emulsification of particles and surfactant led to synergistic stabilization at intermediate concentrations of surfactant; emulsions completely stable to both creaming and coalescence exist at low overall emulsifier concentration. Using the adsorption isotherm of surfactant on particles and the viscosity and optical density of aqueous particle dispersions, we show that the most stable emulsions are formed from dispersions of flocculated, partially hydrophobic particles. From equilibrium contact angle and oil-water interfacial tension measurements, the calculated free energy of adsorption E of a silica particle to the oil-water interface passes through a maximum with respect to surfactant concentration, in line with the emulsion stability optimum. This results from a competition between the influence of particle hydrophobicity and interfacial tension on the magnitude of E. PMID:17241019

  20. Studies on the formation of bifenthrin oil-in-water nano-emulsions prepared with mixed surfactants

    Microsoft Academic Search

    Ying Liu; Fanglin Wei; Yangyang Wang; Guonian Zhu

    2011-01-01

    The formation of oil-in-water (O\\/W) nano-emulsions suitable for pesticidal application has been studied in water\\/mixture of non-ionic surfactant (C12E3) and anion surfactant (MAPK)\\/oil (bifenthrin dissolved in dimethylbenzene) systems. The nano-emulsions with constant oil concentration were prepared by using high-energy emulsification methods. Effects of surfactant ratio and total surfactant concentration on the mean droplet size and size distribution of the emulsions

  1. Breaking crude oil emulsions by the action of surfactants

    SciTech Connect

    Tronov, V.P.

    1983-07-01

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

  2. Tuning active emulsion dynamics via surfactants and topology.

    PubMed

    Thutupalli, Shashi; Herminghaus, Stephan

    2013-08-01

    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

  3. Influence of the surfactant nature on the calcium carbonate synthesis in water-in-oil emulsion

    NASA Astrophysics Data System (ADS)

    Szcze?, Aleksandra

    2009-02-01

    Calcium carbonate has been precipitated from water-in-oil emulsions consisting of n-hexane/nonionic surfactant (Brij 30) and its mixture with cationic (DTAB) or anionic surfactant (SDS) to which calcium chloride and sodium carbonate were added. It was found that the surfactant kind and its amount can regulate the size, form and morphology of the precipitated particles. In case of nonionic surfactant the water/surfactant ratio is the most important parameter that allows to obtain small and regular calcium carbonate crystals. Addition of the DTAB results in different morphology of particles having the same crystal form, whereas addition of SDS changes the kind of emulsion from water-in-oil to oil-in-water. Moreover, light transmittance and backscattering light measurements have been used as a method to study the kinetics of calcium carbonate precipitation in emulsion systems.

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

    PubMed

    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

    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

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

    PubMed

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

    2005-10-15

    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

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

    PubMed Central

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

    2009-01-01

    Recent efforts in our laboratory have explored the use of polyacrylate nanoparticles in aqueous media as stable emulsions for potential applications in treating drug-resistant bacterial infections. These emulsions are made by emulsion polymerization of acrylated antibiotic compounds in a mixture of butyl acrylate and styrene (7:3 w:w) using sodium dodecyl sulfate (SDS) as a surfactant. Prior work in our group established that the emulsions required purification to remove toxicity associated with extraneous surfactant present in the media. This paper summarizes our investigations of poly(butyl acrylate-styrene) emulsions made using anionic, cationic, zwitterionic, and non-charged (amphiphilic) surfactants, as well as attachable surfactant monomers (surfmers), comparing the cytotoxicity and microbiological activity levels of the emulsion both before and after purification. Our results show that the attachment of a polymerizable surfmer onto the matrix of the nanoparticle neither improves nor diminishes cytotoxic or antibacterial effects of the emulsion, regardless of whether the emulsions are purified or not, and that the optimal properties are associated with the use of the non-ionic surfactants versus those carrying anionic, cationic, or zwitterionic charge. Incorporation of an N-thiolated ?-lactam antibacterial agent onto the nanoparticle matrix via covalent attachment endows the emulsion with antibiotic properties against pathogenic bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), without changing the physical properties of the nanoparticles or their emulsions. PMID:19523413

  7. Nano-emulsion formulation using spontaneous emulsification: solvent, oil and surfactant optimisation.

    PubMed

    Bouchemal, K; Briançon, S; Perrier, E; Fessi, H

    2004-08-01

    Nano-emulsions consist of fine oil-in-water dispersions, having droplets covering the size range of 100-600 nm. In the present work, nano-emulsions were prepared using the spontaneous emulsification mechanism which occurs when an organic phase and an aqueous phase are mixed. The organic phase is an homogeneous solution of oil, lipophilic surfactant and water-miscible solvent, the aqueous phase consists on hydrophilic surfactant and water. An experimental study of nano-emulsion process optimisation based on the required size distribution was performed in relation with the type of oil, surfactant and the water-miscible solvent. The results showed that the composition of the initial organic phase was of great importance for the spontaneous emulsification process, and so, for the physico-chemical properties of the obtained emulsions. First, oil viscosity and HLB surfactants were changed, alpha-tocopherol, the most viscous oil, gave the smallest droplets size (171 +/- 2 nm), HLB required for the resulting oil-in-water emulsion was superior to 8. Second, the effect of water-solvent miscibility on the emulsification process was studied by decreasing acetone proportion in the organic phase. The solvent-acetone proportion leading to a fine nano-emulsion was fixed at 15/85% (v/v) with EtAc-acetone and 30/70% (v/v) with MEK-acetone mixture. To strength the choice of solvents, physical characteristics were compared, in particular, the auto-inflammation temperature and the flash point. This phase of emulsion optimisation represents an important step in the process of polymeric nanocapsules preparation using nanoprecipitation or interfacial polycondensation combined with spontaneous emulsification technique. PMID:15265563

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

    SciTech Connect

    Roar Skartlien; Espen Sollum; Andreas Akselsen; Paul Meakin

    2012-07-01

    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.

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

    PubMed Central

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

    2010-01-01

    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. PMID:20218695

  10. The stability of high internal phase emulsions at low surfactant concentration studied by small angle neutron scattering

    Microsoft Academic Search

    Philip A. Reynolds; Duncan J. McGillivray; Jitendra P. Mata; Peter N. Yaron; John W. White

    2010-01-01

    The changes in structure of high internal phase emulsions at low concentrations and at elevated temperature are reported for comparison with the same emulsions under conditions well away from instability. Small angle neutron scattering measurements on aqueous ammonium nitrate droplets dispersed in hexadecane and stabilized by very small quantities of a polyisobutylene-based surfactant (PIBSA) as well as related inverse micellar

  11. Dynamic behavior of natural sea surfactant films

    NASA Astrophysics Data System (ADS)

    Mass, John T.; Milgram, Jerome H.

    1998-07-01

    The dynamic behavior of sea surfactants is studied at timescales from 0.04 to 2 seconds by generating waves on the water containing its natural surfactants in the laboratory and comparing dynamical measurements with theoretical predictions for prescribed surfactant properties. The properties considered are film pressure, elasticity and surface viscosity. For longitudinal Marangoni waves in the frequency range of 0.5 to 4.0 Hz, time-varying film pressures are measured. For transverse waves in the frequency range of 3 to 25 Hz, spatial decay rates are measured. Prior to conducting experiments with sea water containing soluble natural surfactants, the procedures and methods of analysis are validated by experiments with clean fresh water and with an insoluble oleyl alcohol film. A notable finding is that the static film elasticity accurately predicts the dynamic behavior of both the insoluble oleyl alcohol film and the soluble natural sea surfactant films. To better understand the reasons for this finding, sea surfactant adsorption and desorption time histories were measured. The adsorption/desorption time scales ranged from 46 to 196 min. One reason for the accurate prediction of surfactant dynamic behavior by the static elasticity is that the timescales of the waves are much shorter than the adsorption/desorption timescales. The conclusion is that the static elasticity controls the interactions of surfactants with most hydrodynamic disturbances having timescales up to several min.

  12. Preparation and physicochemical properties of surfactant-free emulsions using electrolytic-reduction ion water containing lithium magnesium sodium silicate.

    PubMed

    Okajima, Masahiro; Wada, Yuko; Hosoya, Takashi; Hino, Fumio; Kitahara, Yoshiyasu; Shimokawa, Ken-ichi; Ishii, Fumiyoshi

    2013-04-01

    Surfactant-free emulsions by adding jojoba oil, squalane, olive oil, or glyceryl trioctanoate (medium chain fatty acid triglycerides, MCT) to electrolytic-reduction ion water containing lithium magnesium sodium silicate (GE-100) were prepared, and their physiochemical properties (thixotropy, zeta potential, and mean particle diameter) were evaluated. At an oil concentration of 10%, the zeta potential was ?22.3 ? ?26.8 mV, showing no marked differences among the emulsions of various types of oil, but the mean particle diameters in the olive oil emulsion (327 nm) and MCT emulsion (295 nm) were smaller than those in the other oil emulsions (452-471 nm). In addition, measurement of the hysteresis loop area of each type of emulsion revealed extremely high thixotropy of the emulsion containing MCT at a low concentration and the olive emulsion. Based on these results, since surfactants and antiseptic agents markedly damage sensitive skin tissue such as that with atopic dermatitis, surfactant- and antiseptic-free emulsions are expected to be new bases for drugs for external use. PMID:23715508

  13. Characteristics and behavior of emulsion at nuclear fuel reprocessing

    SciTech Connect

    Gonda, K.; Nemoto, T.; Oka, K.

    1982-05-01

    The characteristics and behavior of the emulsion formed in mixer-settlers during nuclear fuel reprocessing were studied with the dissolver solution of spent fuel burned up to 28,000 MWd/MTU and a palladium colloidal solution, respectively. The emulsion was observed to be oil in water where nonsoluble residues of spent fuel were condensed as emulsifiers. Emulsion formed at interfaces in the settler showed electric conductivity due to continuity of the aqueous phase of the emulsion and viscosity due to the creamy state of the emulsion. The higher the palladium particle concentration was, the larger the amount of emulsion formed. This result agreed well with experience obtained in the Tokai Reprocessing Plant operation that both nonsoluble residues and emulsion formation increased remarkably on fuels in which burnup exceeded 20 000 MWd/MTU.

  14. Behavior and fate of surfactants in soil

    SciTech Connect

    Kuhnt, G. (Univ. of Kiel (Germany). Dept. of Geography)

    1993-10-01

    Although a growing number of investigations have dealt with selected aspects of the behavior of surfactants in soil and their effects on various soil properties, systematic approaches like those applied to pesticides or heavy metals are still rare. Considering that soil is exposed to a considerable quantity of surfactants, it would appear necessary to do more intensified research in this field. Based on a comprehensive review of the literature, the author briefly outlines the behavior and fate of surfactants in soil and presents a synopsis from the viewpoint of a pedologist. Even at low concentrations, surfactants seem to alter soil physics, soil chemistry, and soil biology significantly, whereby sorption processes play a dominant role. The report tries to integrate the most important research results in this field and to interpret them against the background of the complex structure of the soil system.

  15. The stability of high internal phase emulsions at low surfactant concentration studied by small angle neutron scattering.

    PubMed

    Reynolds, Philip A; McGillivray, Duncan J; Mata, Jitendra P; Yaron, Peter N; White, John W

    2010-09-15

    The changes in structure of high internal phase emulsions at low concentrations and at elevated temperature are reported for comparison with the same emulsions under conditions well away from instability. Small angle neutron scattering measurements on aqueous ammonium nitrate droplets dispersed in hexadecane and stabilized by very small quantities of a polyisobutylene-based surfactant (PIBSA) as well as related inverse micellar solutions in hexadecane, have been made as a function of temperature and surfactant concentration. Experimental conditions here favour larger and more deformable droplets than in previous studies. Besides the expected micelles and adsorbed surfactant, planar bilayers of micron lateral extent between touching droplets cover 20% of the droplet surface. Another difference from previous experiments is that the oil phase in the emulsions, and corresponding inverse micellar solutions are different in micellar radii and composition. The differences, and changes with surfactant concentration and temperature, are attributed to fractionation of the polydisperse PIBSA in the emulsions, but not the inverse micellar solutions. At low PIBSA concentration and high temperature the SANS shows emulsion decomposing into separate oil and aqueous phases. This occurs when the micelle concentration reaches a very small but measurable value. The inverse micelles may suppress by steric action long wavelength unstable capillary waves in the bilayers. Depletion repulsion forces here have a minor role in the emulsion stabilization. PMID:20573351

  16. Ceramic membrane fouling during ultrafiltration of oil/water emulsions: roles played by stabilization surfactants of oil droplets.

    PubMed

    Lu, Dongwei; Zhang, Tao; Ma, Jun

    2015-04-01

    Oil/water (O/W) emulsion stabilized by surfactants is the part of oily wastewater that is most difficult to handle. Ceramic membrane ultrafiltration presently is an ideal process to treat O/W emulsions. However, little is known about the fouling mechanism of the ceramic membrane during O/W emulsion treatment. This paper investigated how stabilization surfactants of O/W emulsions influence the irreversible fouling of ceramic membranes during ultrafiltration. An unexpected phenomenon observed was that irreversible fouling was much less when the charge of the stabilization surfactant of O/W emulsions is opposite to the membrane. The less ceramic membrane fouling in this case was proposed to be due to a synergetic steric effect and demulsification effect which prevented the penetration of oil droplets into membrane pores and led to less pore blockage. This proposed mechanism was supported by cross section images of fouled and virgin ceramic membranes taken with scanning electron microscopy, regression results of classical fouling models, and analysis of organic components rejected by the membrane. Furthermore, this mechanism was also verified by the existence of a steric effect and demulsification effect. Our finding suggests that ceramic membrane oppositely charged to the stabilization surfactant should be applied in ultrafiltration of O/W emulsions to alleviate irreversible membrane fouling. It could be a useful rule for ceramic membrane ultrafiltration of oily wastewater. PMID:25730119

  17. Highly CO2/N2-switchable zwitterionic surfactant for pickering emulsions at ambient temperature.

    PubMed

    Liu, Pingwei; Lu, Weiqiang; Wang, Wen-Jun; Li, Bo-Geng; Zhu, Shiping

    2014-09-01

    Cross-linked polymer particles were prepared via surfactant-free emulsion copolymerization of 2-(diethylamino)ethyl methacrylate (DEAEMA) and sodium methacrylate (SMA) using N,N'-methylenebis(acrylamide) (MBA) as a cross-linker. Generated particles are zwitterionic, possessing unique isoelectric points in the pH range of 7.5-8.0, which is readily tunable through CO2/N2 bubbling. The particles were found to be highly responsive to CO2/N2 switching, dissolving in water with CO2 bubbling and precipitating with N2 bubbling at room temperature. Pickering emulsions of n-dodecane were prepared using these particles as the sole emulsifier. These emulsions can be rapidly demulsified with CO2 bubbling, resulting in complete oil/water phase separations. Nitrogen bubbling efficiently re-emulsifies the oil with the aid of homogenization. The rapid emulsification/demulsification using CO2/N2 bubbling at room temperature provides these cross-linked zwitterionic particles with distinct advantages as functional Pickering surfactants. PMID:25105821

  18. TAG CRYSTALLIZATION IN EMULSIONS : DSC\\/XRDT STUDY OF TRIACYLGLYCEROL POLYMORPHISM INFLUENCED BY EMULSIFIER CONCENTRATION

    Microsoft Academic Search

    D. Kalnin; O. Schafer; H. Amenitsch; M. Ollivon

    Characterization of crystallization behavior of fats within emulsion droplets of oil in water emulsions -of pharmaceutical and agronomic interest- is the main focus of this research. Due to the multiplicity of components added - proteins, hydrocolloids and other surfactants - which are all susceptible to influence the emulsions' crystallization behavior - investigation of emulsions can be difficult (1,2,3). Triglycerides (TAGs),

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

    NASA Astrophysics Data System (ADS)

    Ryoo, Won Sun

    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.

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

    NASA Astrophysics Data System (ADS)

    Skartlien, R.; Grimes, B.; Meakin, P.; Sjöblom, J.; Sollum, E.

    2012-12-01

    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 (2563 ˜ 107 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 form D ˜ [ln (ct)]? for the morphology length, or exponential scalings associated with arrested growth, on the basis of the phenomenological model.

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

    PubMed

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

    2010-11-15

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

  2. Nonlinear rheology of a dilute emulsion of surfactant-covered spherical drops in time-dependent flows

    NASA Astrophysics Data System (ADS)

    Vlahovska, P.; Blawzdziewicz, J.; Loewenberg, M.

    2002-07-01

    The effect of an insoluble surfactant on the rheological behaviour of a dilute emulsion is theoretically studied under low-capillary-number conditions. The dynamics depends on three dimensionless time-scale parameters that characterize the strength of the mechanisms that control the magnitude of the distortion of the surfactant distribution on the drop interface. These mechanisms include Marangoni relaxation, drop rotation by the imposed flow, and oscillations of the imposed flow. The interaction of the time scales gives rise to a complex rheological behaviour. The evolution of the system is described by a nonlinear matrix equation derived by expanding the fluid velocity and surfactant distribution in spherical harmonics. Analytical expansions are developed for conditions where the surfactant distribution is only slightly perturbed, which occurs when one of the time-scale parameters is small.

  3. Chemomechanical behaviors of polymer gels by surfactant binding

    NASA Astrophysics Data System (ADS)

    Narita, Tetsuharu; Gong, Jianping; Osada, Yoshihito

    1999-05-01

    A weakly crosslinked poly(2-acrylamido-2-methylpropanesulfonic acid) immersed in cationic surfactant (N-n-alkylpyridinium chloride) shows biomimetic chemomechanical movement under dc current. The principle of the movement is based on an electrokinetic molecular assembly reaction of the surfactant onto the polymer network. In order to analyze the diffusion and binding processes which are both of importance for understanding the alkyl size dependence of the chemomechanical behavior, kinetic studies of the surfactants binding were made systematically changing the alkyl size and concentration of the surfactants and ionic strength. It was found that the driving force of the surfactant diffusion is the electrochemical potential gradient, while the surfactant binding enhances the diffusion proces. A mathematical model for the surfactant diffusion was developed taking account of the surfactant binding process and obtained results were well explained the experimental observations.

  4. Preparation and characterization of surfactant-free polystyrene/layered double hydroxide exfoliated nanocomposite via soap-free emulsion polymerization.

    PubMed

    Qiu, Longzhen; Qu, Baojun

    2006-09-15

    The soap-free emulsion polymerization has been applied for preparing the surfactant-free polystyrene/layered double hydroxide exfoliated nanocomposite. The XRD and TEM determinations have been used to monitor the changes of interlayer spacing and morphology during polymerization. The results show that the obtained nanocomposite has the homogeneous structure of polymeric and inorganic components. Due to the absence of organic surfactant, the PS/LDH nanocomposite shows a remarked improvement on the onset decomposition temperature compared with virgin PS. PMID:16793051

  5. On the stability of surfactant-free water-in-oil emulsions and synthesis of hollow SiO 2 nanospheres

    Microsoft Academic Search

    Satoshi Horikoshi; Yu Akao; Taku Ogura; Hideki Sakai; Masahiko Abe; Nick Serpone

    2010-01-01

    This article examines the relative stability of five surfactant-free water-in-oil (w\\/o) emulsions produced by 1-min irradiation of the mixture with 42-kHz ultrasounds; it also reports on the synthesis of hollow silica nanospheres in such emulsions. The oily phase in these w\\/o emulsions consisted of cyclohexane, dodecane, benzene, octane, and hexane, whereas the dispersed phase consisted of aqueous ammonia at pH

  6. Surfactant kinetics and their importance in nucleation events in (mini)emulsion polymerization revealed by quartz crystal microbalance with dissipation monitoring.

    PubMed

    Ballard, Nicholas; Urrutia, Jone; Eizagirre, Simone; Schäfer, Thomas; Diaconu, Gabriela; de la Cal, José C; Asua, José M

    2014-08-01

    Surfactants are vital components of almost all heterogeneous polymerizations for maintaining colloidal stability, but they also play an important role in the kinetics and mechanism of particle nucleation. Despite many decades of research, the knowledge of adsorption-desorption surfactant kinetics and their application in (mini)emulsion polymerization is largely based on qualitative arguments. In this paper we show that the use of a quartz crystal microbalance with dissipation monitoring can provide quantitative information on both the adsorption equilibrium of ionic and nonionic surfactants, and also the kinetics of adsorption/desorption, that can be applied to the understanding of nucleation processes in (mini)emulsion polymerization. We show that surfactant dynamics and nucleation phenomena in (mini)emulsion polymerization are not dominated by diffusion phenomena linked to molecular size of surfactant as previously thought but rather are driven by the large differences in the rate of surfactant adsorption and desorption at the polymer-water interface. Finally, we show the application of this knowledge to explain the differences between nucleation processes for ionic and nonionic surfactants in emulsion polymerization. PMID:25033420

  7. A general method for synthesizing enzyme-polymer conjugates in reverse emulsions using Pluronic as a reactive surfactant.

    PubMed

    Wu, Xiaoling; Ge, Jun; Zhu, Jingying; Zhang, Yifei; Yong, You; Liu, Zheng

    2015-05-28

    Using aldehyde-functionalized Pluronic as the reactive surfactant, enzyme-Pluronic conjugates with sizes ranging from nanometers to micrometers were synthesized in reverse emulsions. Compared with the direct conjugation in aqueous solution, this method gave an increased conjugation efficiency and well-controlled size of the conjugates. The versatility of this method was validated using horseradish peroxidase (HRP), Candida rugosa lipase (CRL) and Candida antarctica lipase B (CALB). The resulting enzyme-Pluronic conjugates showed greatly enhanced apparent activity compared to free enzymes in organic media. PMID:25977947

  8. Effects of Inorganic and Organic Salts on Aggregation Behavior of Cationic Gemini Surfactants

    E-print Network

    Huang, Jianbin

    Effects of Inorganic and Organic Salts on Aggregation Behavior of Cationic Gemini Surfactants) values of the cationic gemini surfactants. The ability to promote the surfactant aggregation decreases the aggregation of surfactants in quite different ways. In recent years, gemini surfactants have attracted great

  9. Aggregation behaviors of a series of anionic sulfonate gemini surfactants and their corresponding monomeric surfactant

    Microsoft Academic Search

    Yingxiong Wang; Yuchun Han; Xu Huang; Meiwen Cao; Yilin Wang

    2008-01-01

    A series of anionic sulfonate gemini surfactants with the general structure of [(CnH2n+1)(C3H6SO?3) NCsN(C3H6SO?3)(CnH2n+1)]?2Na+ have been synthesized. While the spacer group Cs represents p-xylyl or (CH2)3, the surfactants are abbreviated as CnCpxCn(SO3)2 (n=8,10,12) or C12C3C12(SO3)2(n=12), respectively. A corresponding monomeric surfactant C12H25N(CH3)(C3H6SO?3)?Na+(C12NSO3) has also been prepared. The aggregation behavior of these surfactants has been studied at pH 9.2 and ionic strength

  10. Stability of emulsions for parenteral feeding: Preparation and characterization of o\\/w nanoemulsions with natural oils and Pluronic f68 as surfactant

    Microsoft Academic Search

    M. Wulff-Pérez; A. Torcello-Gómez; M. J. Gálvez-Ruíz; A. Martín-Rodríguez

    2009-01-01

    For hydrophobic bioactive compounds, poor water solubility is a major limiting factor for their use in different applications in the field of food industry or pharmacy. For this reason they are administrated as emulsions, in which the substance is dissolved in an organic compound, which is dispersed in an aqueous phase as droplets stabilized by a surfactant. It has been

  11. Aggregation behavior of p-n-alkylbenzamidinium chloride surfactants.

    PubMed

    Talhout, Reinskje; Stafforst, Thorsten; Engberts, Jan B F N

    2004-08-01

    The aggregation behavior of a novel class of surfactants, p-n-alkylbenzamidinium chlorides, has been investigated. The thermodynamics of aggregation of p-n-decylbenzamidinium chloride mixed with cationic and anionic cosurfactants has been studied using isothermal titration calorimetry. For mixtures of p-n-decylbenzamidinium chloride with n-alkyltrimethylammonium chlorides, the aggregation process is enthalpically more favorable than for the pure n-alkyltrimethylammonium chlorides, probably caused by diminished headgroup repulsion due to charge delocalization in the amidinium headgroup. A critical aggregation concentration between 3 and 4 mM has been extrapolated for p-n-decylbenzamidinium chloride at 40 degrees C, around two times lower than that of similar surfactants without charge delocalization in the headgroup and well comparable to that of similar surfactants with charge delocalization in the headgroup. In mixtures of p-n-decylbenzamidinium chloride with either sodium n-alkylsulfates or sodium dodecylbenzenesulfonate, evidence is found for the formation of bilayer aggregates by the pseudo-double-tailed catanionic surfactants composed of p-n-decylbenzamidinium and the anionic surfactant. These aggregates are solubilized to mixed micelles by excess free anionic surfactant at the measured critical aggregation concentration. PMID:15219451

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

    NASA Astrophysics Data System (ADS)

    MacLean, Duncan A.

    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.

  13. Fate, behavior and effects of surfactants and their degradation products in the environment

    Microsoft Academic Search

    Guang-Guo Ying

    2006-01-01

    Surfactants are widely used in household and industrial products. After use, surfactants as well as their products are mainly discharged into sewage treatment plants and then dispersed into the environment through effluent discharge into surface waters and sludge disposal on lands. Surfactants have different behavior and fate in the environment. Nonionic and cationic surfactants had much higher sorption on soil

  14. Surfactant effects on environmental behavior of pesticides.

    PubMed

    Katagi, Toshiyuki

    2008-01-01

    The potential effects of adjuvants, including surfactants used in pesticide formulation, have been extensively studied for many small organic chemicals, but similar investigation on pesticides is limited in most cases. Solubilizing effects leading to the apparently increased water solubility of a pesticide are commonly known through the preparation of formulations, but fundamental profiles, especially for a specific monodisperse surfactant, are not fully studied. Reduced volatilization of a pesticide from the formulation can be explained by analogy of a very simple organic chemical, but the actual mechanism for the pesticide is still obscure. In contrast, from the point of view of avoiding groundwater contamination with a pesticide, adsorption/desorption profiles in the presence of surfactants and adjuvants have been examined extensively as well as pesticide mobility in the soil column. The basic mechanism in micelle-catalyzed hydrolysis is well known, and theoretical approaches including the PPIE model have succeeded in explaining the observed effects of surfactants, but its application to pesticides is also limited. Photolysis, especially in an aqueous phase, is in the same situation. The dilution effect in the real environment would show these effects on hydrolysis and photolysis to be much less than expected from the laboratory basic studies, but more information is necessary to examine the practical extent of the effects in an early stage of applying a pesticide formulation to crops and soil. Many adjuvants, including surfactants, are biodegradable in the soil environment, and thus their effects on the biodegradation of a pesticide in soil and sediment may be limited, as demonstrated by field trials. Not only from the theoretical but also the practical aspect, the foliar uptake of pesticide in the presence of adjuvants has been investigated extensively and some prediction on the ease of foliar uptake can be realized in relation to the formulation technology. However, effect on root uptake of pesticides is to be further investigated. In an aqueous environment more or less contaminated by various chemicals such as detergents and their degradates, it is necessary to investigate the effect of adjuvants on uptake, bioconcentration, and trophic transfer of pesticides for better understanding of pesticide contamination of aquatic species in the aquatic environment. PMID:18069647

  15. Characterization of surfactants in an oil-in-water emulsion-based vaccine adjuvant using MS and HPLC-MS: structural analysis and quantification.

    PubMed

    Cotte, Jean-François; Sonnery, Sylvain; Martial, Fabien; Dubayle, Jean; Dalençon, François; Haensler, Jean; Adam, Olivier

    2012-10-15

    Mass spectrometry (MS) and high performance liquid chromatography coupled to mass spectrometry (HPLC-MS) techniques were developed to characterize two surfactants, cetheareth-12 and sorbitan oleate, used to manufacture AF03, an emulsified oil-in-water (O/W) adjuvant. MS was first used to characterize the chemical structure and determine the composition of the two surfactants. The two surfactants appeared as complex products, in particular with respect to the nature of the fatty alcohols and the distribution of the number of ethylene oxides in cetheareth-12, and with respect to the different sorbitan-bound fatty acids (oleic, linoleic and palmitic acids) in sorbitan oleate. Subsequently, once the ions of interest were determined and selected, HPLC-MS was developed and optimized to quantify and to "quality control" the two surfactants as raw materials and as ingredients in the final O/W emulsion bulk and filled products. PMID:22713283

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

    SciTech Connect

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

    1995-04-01

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

  17. Theoretical and experimental investigation of the equilibrium and dynamic interfacial behavior of mixed surfactant solutions

    E-print Network

    Mulqueen, Michael (Michael Patrick), 1972-

    2001-01-01

    In many commercial applications involving surfactants, the desired properties are controlled by both the equilibrium and the dynamic interfacial behavior. In particular, surfactant adsorption at air-water interfaces causes ...

  18. Modeling Thermodynamic Behavior of Nonionic Surfactants in Water

    NASA Astrophysics Data System (ADS)

    Ginzburg, Valeriy; Varineau, Pierre

    2009-03-01

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

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

    PubMed

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

    2010-04-15

    Surfactant-free emulsion polymerization (SFEP) is a well-known technique for the production of polymeric nanoparticles that does not require post-synthetic cleaning steps. Obtaining hydrophobic particles at sub-100 nm scale, however, is quite challenging with this polymerization method. Here, we demonstrate a single step synthetic approach that yields poly(methylmethacrylate) (PMMA) nanoparticles with controlled sub-100 nm size and relatively high resultant solid content. Dynamic light scattering (DLS) was used for the particle characterization. Spherical and uniformly sized nanoparticles were confirmed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Acetone was used as a cosolvent in order to obtain monodisperse sub-100 nm diameter particles. Stable PMMA nanoparticle dispersions were obtained for all formulations where the persulfate initiator causes the negative charges on the particle surface. The effects of acetone, monomer and initiator concentration were studied to optimize average particle hydrodynamic diameter and polydispersity index of the final particles. Non-crosslinked monodisperse PMMA nanoparticles (polydispersity index less than 0.05) with diameters from 32 nm to 72 nm were synthesized by using this method. PMID:20138293

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

    PubMed

    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

    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

  1. Behavior of Malondialdehyde in Oil-in-Water Emulsions.

    PubMed

    Vandemoortele, Angelique; De Meulenaer, Bruno

    2015-06-17

    The impact of temperature, emulsifier, and protein type on the reactivity of malondialdehyde in oil-in-water emulsions was elucidated. Malondialdehyde recoveries in aqueous buffer, protein solutions, saturated oil, and fully hydrogenated coconut oil-in-water emulsions stabilized by whey proteins or Tween 20 at 4 or 40 °C were compared. At both temperatures, the reactivity of malondialdehyde in aqueous buffer was the same. In protein solutions, malondialdehyde concentrations were reduced further and its decrease was protein-dependent. Similar trends were found for emulsions. Surprisingly, malondialdehyde was very reactive in saturated oil because only 15% was recovered at 40 °C. However, the degradation in oil proved to be strongly temperature-dependent; at 4 °C, losses amounted to only 8%. This study revealed that malondialdehyde is a very reactive molecule, both in the presence and absence of proteins. Its use as a general oxidation marker should therefore be considered with care. PMID:26016781

  2. Alkyl-imidazolium glycosides: non-ionic-cationic hybrid surfactants from renewable resources.

    PubMed

    Salman, Abbas Abdulameer; Tabandeh, Mojtaba; Heidelberg, Thorsten; Hussen, Rusnah Syahila Duali; Ali, Hapipah Mohd

    2015-08-14

    A series of surfactants combining carbohydrate and imidazolium head groups were prepared and investigated on their assembly behavior. The presence of the imidazolium group dominated the interactions of the surfactants, leading to high CMCs and large molecular surface areas, reflected in curved rather than lamellar surfactant assemblies. The carbohydrate, on the other hand, stabilized molecular assemblies slightly and reduced the surface tension of surfactant solutions considerably. A comparative emulsion study discourages the use of pure alkyl imidazolium glycosides owing to reduced assembly stabilities compared with APGs. However, the surfactants are believed to have potential as component in carbohydrate based surfactant mixtures. PMID:26000863

  3. VISCOELASTIC BEHAVIOR OF POLYMER-THICKENED WATER-IN-OIL EMULSIONS

    E-print Network

    Natelson, Douglas

    VISCOELASTIC BEHAVIOR OF POLYMER-THICKENED WATER-IN- OIL EMULSIONS MONTESI PEÑA HIRASAKI PASQUALI Chemical Engineering Department, Rice University, 6100 Main St. MS 362. Houston, USA 77005 The viscoelastic with the water content, and to a significantly less extent with the presence of polymer. Similarly, G', G

  4. Effect of Shear Flow on the Phase Behavior of an Aqueous Gelatin-Dextran Emulsion

    E-print Network

    Effect of Shear Flow on the Phase Behavior of an Aqueous Gelatin-Dextran Emulsion Y. A. Antonov, P and on a time resolved basis the shear induced morphology in ternary two-phase water-gelatin-dextran mixtures forces of the self-association process of the gelatin. The isothermal phase diagram at a fixed shear rate

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

    SciTech Connect

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

    1993-11-01

    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.

  6. Effect of selected non-ionic surfactants on the flow behavior of aqueous veegum suspensions.

    PubMed

    Kennedy, Ross A; Kennedy, Michelle L

    2007-01-01

    The aim of this work was to investigate the influence of some non-ionic surfactants, Tween 80 and Brij 98, on the viscosity and flow behavior of a commercial montmorillonite clay, Veegum Granules. The effect of different concentrations of the surfactants on the shear stress-shear rate rheograms of hydrated concentrated clay suspensions was determined by shear viscometry. The addition of either surfactant increased the plastic viscosity and the yield stress of the suspensions. Furthermore, both surfactants altered the thixotropy of the suspensions to an extent that depended on both the surfactant concentration and the time of equilibration of the surfactant and Veegum. Brij 98 had a greater and more rapid effect. It is proposed that the surfactant polar head-groups anchor at the tetrahedral sheet surface, leaving the alkyl chains extending away from the edges and faces. Consequently, the alkyl chains undergo hydrophobic interactions that facilitate the association between the platelets and increase the physical structure within the suspension. Stereochemical differences between the polar groups may lead to differences in the way the surfactants associate with the tetrahedral sheet and hence their ultimate effect on the rheological behavior. There is a significant interaction between these surfactants and montmorillonite clays, and the rheological changes that occur could have a major impact on any pharmaceutical formulation that uses these ingredients. PMID:17408224

  7. A theoretical study of Gemini surfactant phase behavior Kristine M. Layn, Pablo G. Debenedetti, and Robert K. Prud'hommea)

    E-print Network

    A theoretical study of Gemini surfactant phase behavior Kristine M. Layn, Pablo G. Debenedetti 08544 Received 14 November 1997; accepted 8 April 1998 Gemini surfactants are a relatively new type phase behavior of ternary mixtures of Gemini surfactant, oil, and water is investigated. Three

  8. Aggregation behavior of a gemini surfactant with a tripeptide spacer.

    PubMed

    Wang, Meina; Han, Yuchun; Qiao, Fulin; Wang, Yilin

    2015-02-28

    A peptide gemini surfactant, 12-G(NH2)LG(NH2)-12, has been constructed with two dodecyl chains separately attached to the two terminals of a glutamic acid-lysine-glutamic acid peptide and the aggregation behavior of the surfactant was studied in aqueous solution. The 12-G(NH2)LG(NH2)-12 molecules form fiber-like precipitates around pH 7.0, and the precipitation range is widened on increasing the concentration. At pHs 3.0 and 11.0, 12-G(NH2)LG(NH2)-12 forms soluble aggregates because each molecule carries two positively charged amino groups at the two ends of the peptide spacer at pH 3.0, while each molecule carries one negatively charged carboxyl group in the middle of the peptide spacer at pH 11.0. 12-G(NH2)LG(NH2)-12 displays a similar concentration-dependent process at these two pHs: forming small micelles above the critical micelle concentration and transferring to fibers at pH 3.0 or twisted ribbons at pH 11.0 above the second critical concentration. The fibers formed at pH 3.0 tend to aggregate into bundles with twisted structure. Both the twisted fibers at pH 3.0 and the twisted ribbons at pH 11.0 contain ?-sheet structure formed by the peptide spacer. PMID:25588349

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

    PubMed

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

    2012-07-24

    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

  10. 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...

  11. Conventional and gemini surfactants embedded within bilayer membranes: contrasting behavior.

    PubMed

    Yaroslavov, A A; Udalykh OYu; Melik-Nubarov, N S; Kabanov, V A; Ermakov, Y A; Azov, V A; Menger, F M

    2001-11-19

    Laser microelectrophoresis (coupled with conductance, fluorescence, and dynamic light scattering) is shown to be a highly instructive tool in comparing the dynamics of conventional and gemini surfactants embedded within vesicle bilayers. The following can be listed among the more important observations and conclusions: a) Cationic conventional surfactant, added to a "solid" (gel) lipid vesicle containing an anionic phospholipid, charge-neutralizes only half the anionic charge. With a "liquid" (liquid crystalline) vesicle, however, the entire negative charge is neutralized. Thus, the cationic conventional surfactant can "flip-flop" readily only in the liquid membrane. b) A cationic gemini surfactant charge-neutralizes only the anionic lipid in the outer membrane leaflet of either solid or liquid membranes, thus indicating an inability to flip-flop regardless of the phase-state of the bilayer. c) Mixed population experiments show that surfactants can hop from one vesicle to another in liquid but not solid membranes. d) In liquid, but not solid, bilayers, a surface-adsorbed cationic polymer can electrostatically "drag" anionic surfactant from the inner leaflet to the outer leaflet where the polymer resides. e) Peripheral fluorescence quenching experiments show that a cationic polymer, adhered to anionic vesicles, can be forced to dissociate in the presence of high concentrations of salt or an anionic polymer. f) Adsorbed polymer, of opposite charge to that imparted to vesicles by a gemini surfactant, is unable to dislocate surfactant even in a liquid membrane. g) In our systems, ionic polymers will not bind to neutral vesicles made solely of zwitterionic phospholipid. On the other hand, ionic polymers bind to neutral vesicles if charge neutrality is obtained by virtue of the membrane containing equimolar amounts of cationic and anionic surfactant. This is attributable to surfactant segregation within the bilayer. h) Experiments prove that polymer migration can occur among a population of neutral ternary vesicles. PMID:11763452

  12. Phase behavior, morphology, and polymorphism of surfactant systems

    NASA Astrophysics Data System (ADS)

    Liang, Jingmei

    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.

  13. Synthesis and Crystallization Behavior of Surfactants with Hexamolybdate as the Polar Headgroup.

    PubMed

    Zhu, Li; Chen, Kun; Hao, Jian; Wei, Zheyu; Zhang, Haocheng; Yin, Panchao; Wei, Yongge

    2015-07-01

    Alkyl chains with different lengths were covalently grafted onto the surface of hexamolybdate through the postfunctionalization protocol of polyoxometalates. The obtained compounds represent typical structures of the so-called giant surfactants. Unexpectedly, those surfactants with hexamolybdates as polar headgroups are able to crystallize, while single-crystal X-ray diffraction reveals that the crystallization behavior of the surfactants is highly dependent on the length of the alkyl chains. For surfactants with comparatively short alkyl chains (C6 and C10), the alkyl chains prefer to interact with tetrabutylammonium, the countercation of hexamolybdate. However, the alkyl chains tend to pack with each other to form a domain of alkyl chains in the surfactant with a longer alkyl chain (C18). The possible mechanism is that a long alkyl chain cannot be fully compatible with the short chain (C4) of tetrabutylammonium. PMID:26067891

  14. Surface properties, aggregation behavior and micellization thermodynamics of a class of gemini surfactants with ethyl ammonium headgroups

    E-print Network

    Huang, Jianbin

    March 2012 Available online 23 March 2012 Keywords: Gemini surfactants Ethyl ammonium headgroups Enhanced aggregation capability Full understanding a b s t r a c t Cationic gemini surfactant homologues properties; (2) aggregation behavior in bulk solution, including (i) morphologies of above gemini surfactants

  15. Dimeric (gemini) surfactants: effect of the spacer group on the association behavior in aqueous solution.

    PubMed

    Zana, Raoul

    2002-04-15

    Dimeric (gemini) surfactants are made up of two amphiphilic moieties connected at the level of, or very close to, the head groups by a spacer group of varying nature: hydrophilic or hydrophobic, rigid or flexible. These surfactants represent a new class of surfactants that is finding its way into surfactant-based formulations. The nature of the spacer group (length, flexibility, chemical structure) has been shown to be of the utmost importance in determining the solution properties of aqueous dimeric surfactants. This paper reviews the effect of the nature of the spacer on some of these properties. The behavior of dimeric surfactants in the submicellar range of concentration, at interfaces, in dilute solution (solubility in water, Krafft temperature, critical micellization concentration, thermodynamics of micelle formation, micelle ionization degree, size, polydispersity, micropolarity and microviscosity, microstructure and rheology of the solutions, solubilization, micelle dynamics, and interaction with polymers) and in concentrated solution (phase behavior) are successively reviewed. Selected results concerning trimeric and tetrameric surfactants are also reviewed. PMID:16290524

  16. Modeling the relationship between the main emulsion components and stability, viscosity, fluid behavior, zeta-potential, and electrophoretic mobility of orange beverage emulsion using response surface methodology.

    PubMed

    Mirhosseini, Hamed; Tan, Chin Ping; Hamid, Nazimah Sheikh Abdul; Yusof, Salmah

    2007-09-19

    The possible relationships between the main emulsion components (namely, Arabic gum, xanthan gum, and orange oil) and the physicochemical properties of orange beverage emulsion were evaluated by using response surface methodology. The physicochemical emulsion property variables considered as response variables were emulsion stability, viscosity, fluid behavior, zeta-potential, and electrophoretic mobility. The independent variables had the most and least significant ( p < 0.05) effect on viscosity and zeta-potential, respectively. The quadratic effect of orange oil and Arabic gum, the interaction effect of Arabic gum and xanthan gum, and the main effect of Arabic gum were the most significant ( p < 0.05) effects on turbidity loss rate, viscosity, viscosity ratio, and mobility, respectively. The main effect of Arabic gum was found to be significant ( p < 0.05) in all response variables except for turbidity loss rate. The nonlinear regression equations were significantly ( p < 0.05) fitted for all response variables with high R (2) values (>0.86), which had no indication of lack of fit. The results indicated that a combined level of 10.78% (w/w) Arabic gum, 0.56% (w/w) xanthan gum, and 15.27% (w/w) orange oil was predicted to provide the overall optimum region in terms of physicochemical properties studied. No significant ( p > 0.05) difference between the experimental and the predicted values confirmed the adequacy of response surface equations. PMID:17708646

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

    PubMed

    Wang, Peng; Keller, Arturo A

    2008-08-01

    Cationic surfactants have been proposed for enhanced sorption zones to contain hydrophobic organic compound (HOC) contamination. Benzalkonium chloride (BC), a cationic surfactant, was selected to study the particle-size dependent sorption behavior of the surfactant and its role in the immobilization of two hydrophobic pesticides (atrazine and diuron) within soil-water-surfactant systems for this application. Five different soils were considered in this study. Our results showed significant particle-size dependent behavior for surfactant sorption and pesticide immobilization in the presence of the sorbed cationic surfactant. The cation exchange capacity (CEC) of the bulk soils and their size fractions (clay, silt, and sand fractions) determined BC sorption capacity. In the absence of BC the sand fractions were the least effective sorbent for the pesticides compared with silts and clays. However, at relatively low BC mass sorbed (<10,000mg/kg) to any of the soil fractions, well below sorption saturation, the sand fractions became more effective sorbents for either pesticide than the clay and silt fractions. The pesticide partitioning coefficient onto sorbed BC (K(ss)) was not constant. Particle CEC, availability of CEC sites for sorption of the cationic surfactant, and the amount of the BC sorbed determined the phase of K(ss). The maximum K(ss) occurred before BC saturation sorption capacity was reached and at different % CEC occupancy for the different size fractions. For the clay fractions, the maximum K(ss) occurred at lower % CEC occupancy ( approximately 30-40%) than for the silt and sand fractions. The maximal K(ss) for the sand fractions occurred at the highest % CEC occupancy among all fractions ( approximately 50-60%). These findings suggest that for an in situ surfactant-enhanced sorption zone it may be better to operate well below the saturation sorption of the cationic surfactant. This would enhance sorption of the HOCs onto the immobile fractions (silt and sand fractions) rather than the potentially mobile clay fractions. PMID:18676001

  18. Studies of the aggregation behavior of cyclic gemini surfactants.

    PubMed

    Jenkins, K M; Wettig, S D; Verrall, R E

    2002-03-15

    The specific conductance, surface tension, mean aggregation number, and apparent molar volume properties of aqueous solutions of a novel series of N,N'-bis(cyclododecyldimethyl)-alpha,omega-alkanediammonium dibromide (c12-s-c12) surfactants, where s is the spacer chain length, are reported. Surfactants with s = 3, 4, and 6 have been prepared and characterized in terms of their Krafft temperature (T(Kr)), critical micelle concentration (cmc), surfactant head group area (a) at the air-water interface, mean aggregation number (N(agg)), and the volume change upon micelle formation (deltaV(phi,M)). The c12-3-c12 shows little evidence of aggregate formation, while the results obtained for the c12-4-c12 and c12-6-c12 homologues suggest the formation of small, poorly defined micellar aggregates in aqueous solution. PMID:16290487

  19. Variation in emulsion stabilization behavior of hybrid silicone polymers with change in molecular structure: Phase diagram study.

    PubMed

    Mehta, Somil C; Somasundaran, P; Kulkarni, Ravi

    2009-05-15

    Silicone oils are widely used in cosmetics and personal care applications to improve softness and condition skin and hair. Being insoluble in water and most hydrocarbons, a common mode of delivering them is in the form of emulsions. Currently most applications use polyoxyethylene (non-ionic) modified siloxanes as emulsifiers to stabilize silicone oil emulsions. However, ionically grafted silicone polymers have not received much attention. Ionic silicones have significantly different properties than the non-ionic counterpart. Thus considerable potential exists to formulate emulsions of silicones with different water/silicone oil ratios for novel applications. In order to understand the mechanisms underlying the effects of hydrophilic modifications on the ability of hybrid silicone polymers to stabilize various emulsions, this article focuses on the phase diagram studies for silicone emulsions. The emulsifying ability of functional silicones was seen to depend on a number of factors including hydrophilicity of the polymer, nature of the functional groups, the extent of modification, and the method of emulsification. It was observed that the region of stable emulsion in a phase diagram expanded with increase in shear rate. At a given shear rate, the region of stable emulsion and the nature of emulsion (water-in-oil or oil-in-water) was observed to depend on hydrophilic-hydrophobic balance of the hybrid silicone emulsifier. At a fixed amount of modification, the non-ionically modified silicone stabilized an oil-in-water emulsion, whereas the ionic silicones stabilized inverse water-in-oil emulsions. This was attributed to the greater hydrophilicity of the polyoxyethylene modified silicones than the ionic counterparts. In general, it is postulated that with progressive increase in hydrophilicity of hybrid silicone emulsifiers, their tendency to stabilize water-in-oil emulsion decreases with corresponding increase in oil-in-water emulsion. Further, this behavior is hypothesized to depend on the nature of modifying functional groups. Thus a hybrid silicone polymer can be tailored by selecting the nature and degree of hydrophilicity to obtain a desired silicone emulsion. PMID:19200558

  20. Diffusion and Scaling Behavior of Polymer-Surfactant Aggregates

    NASA Astrophysics Data System (ADS)

    Chari, Krishnan; Antalek, Brian; Minter, John

    1995-05-01

    The self-diffusion coefficient of poly(ethyleneoxide) (PEO) in self-assembled aggregates of PEO and sodium dodecyl sulfate (SDS) in water at PEO concentrations well below the overlap point has been determined by pulse gradient spin echo NMR spectroscopy. The results show that individual polymer coils undergo significant expansion upon complexation with the surfactant. The diffusion coefficients of PEO coils saturated with SDS scale with molecular weight of the polymer as D~M?app with ?app = 0.60+/-0.02. The value of ?app in this case is different from ?app = 0.55+/-0.01 for the surfactant free coil.

  1. Method for the resolution of enhanced oil recovery emulsions

    SciTech Connect

    Shaw, D.L.

    1984-04-24

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

  2. General rules for the scaling behavior of linear wormlike micelles formed in catanionic surfactant systems.

    PubMed

    Fan, Haiming; Yan, Yun; Li, Zichen; Xu, Yi; Jiang, Lingxiang; Xu, Limin; Zhang, Bo; Huang, Jianbin

    2010-08-15

    We report in this work on the scaling behavior of wormlike micelles formed in a series of mixed systems of oppositely charged surfactants, including sodium decanote (SD)/hexadecyltrimethylammonium bromide (CTAB), sodium laurate (SL)/hexadecyltrimethylammonium bromide, sodium didecaminocystine (SDDC)/hexadecyltrimethylammonium bromide, and sodium dilauraminocystine (SDLC)/hexadecyltrimethylammonium bromide. Steady and dynamic rheological measurements were performed to characterize these wormlike micelles. The scaling behavior for these systems at various mixing ratios was systematically investigated and was compared with that given by the Cates model. It was found that the Cates law can be applied in these systems simply by manipulating the mixing ratio or the surfactant structure. Energetic analysis demonstrates that the scaling behavior of wormlike micelles in nonequimolar mixed cationic and anionic surfactant systems can be close to that predicted by the Cates model, if the electrostatic contribution is below a threshold value. PMID:20621820

  3. Phase and steady shear behavior of dilute carbon black suspensions and carbon black stabilized emulsions.

    PubMed

    Godfrin, Michael P; Tiwari, Ayush; Bose, Arijit; Tripathi, Anubhav

    2014-12-30

    We use para-amino benzoic acid terminated carbon black (CB) as a model particulate material to study the effect of salt-modulated attractive interactions on phase behavior and steady shear stresses in suspensions and particle-stabilized emulsions. Surprisingly, the suspension displayed a yield stress at a CB volume fraction of ?CB = 0.008. The yield stress scaled with CB concentration with power law behavior; the power law exponent changed abruptly at a critical CB concentration, suggesting a substantial change in network structure. Cryogenic scanning electron microscopy revealed structural differences between the networks found in each scaling regime. Randomly oriented pores with thick CB boundaries were observed in the scaling region above the critical particle concentration, suggesting a strong gel network, and long, oriented pores were found in the scaling region below the critical particle concentration, suggesting a weak network influenced by an induced shear stress. These findings correlate with the existence of gels and transient networks. Transient networks break down under gravitational forces over time periods of 12-24 hours. The yield stresses of CB-gels containing oil emulsion droplets were found to scale with carbon black concentration similar to the CB-gels without oil. These results offer insight into salt-induced attractive colloidal networks and the difference in structure and yield-stress behavior between transient networks and gels. Furthermore, CB offers the ability to stabilize an oil phase in discrete droplets and contain them within a rigid network structure. PMID:25469772

  4. Growth Behavior, Geometrical Shape, and Second CMC of Micelles Formed by Cationic Gemini Esterquat Surfactants.

    PubMed

    Bergström, L Magnus; Tehrani-Bagha, Alireza; Nagy, Gergely

    2015-04-28

    Micelles formed by novel gemini esterquat surfactants have been investigated with small-angle neutron scattering (SANS). The growth behavior of the micelles is found to differ conspicuously depending on the length of the gemini surfactant spacer group. The gemini surfactant with a long spacer form rather small triaxial ellipsoidal tablet-shaped micelles that grow weakly with surfactant concentration in the entire range of measured concentrations. Geminis with a short spacer, on the other hand, form weakly growing oblates or tablets at low concentrations that start to grow much more strongly into polydisperse rodlike or wormlike micelles at higher concentrations. The latter behavior is consistent with the presence of a second CMC that marks the transition from the weakly to the strongly growing regime. It is found that the growth behavior in terms of aggregation number as a function of surfactant concentration always appear concave in weakly growing regimes, while switching to convex behavior in strongly growing regimes. As a result, we are able to determine the second CMC of the geminis with short spacer by means of suggesting a rather precise definition of it, located at the point of inflection of the growth curve that corresponds to the transition from concave to convex growth behavior. Our SANS results are rationalized by comparison with the recently developed general micelle model. In particular, this theory is able to explain and reproduce the characteristic appearances of the experimental growth curves, including the presence of a second CMC and the convex strongly growing regime beyond. By means of optimizing the agreement between predictions from the general micelle model and results from SANS experiments, we are able to determine the three bending elasticity constants spontaneous curvature, bending rigidity, and saddle-splay constant for each surfactant. PMID:25835031

  5. Stability criteria for emulsions

    NASA Astrophysics Data System (ADS)

    Bibette, J.; Morse, D. C.; Witten, T. A.; Weitz, D. A.

    1992-10-01

    The coalescence of monodisperse silicone oil-in-water emulsions stabilized with sodium dodecyl sulfate has been studied. We report the existence of a sharp destabilization threshold, controlled by surfactant chemical potential, osmotic pressure, and droplet diameter, at which the rate of coalescence increases dramatically. We present evidence that the stability of the emulsions can be characterized by two microscopic parameters: a minimum stable value of the surfactant chemical potential and a maximum value of the pressure exerted upon a droplet-droplet interface.

  6. Interfacial behavior and structural properties of a clinical lung surfactant from porcine source.

    PubMed

    Blanco, Odalys; Cruz, Antonio; Ospina, Olga L; López-Rodriguez, Elena; Vázquez, Luis; Pérez-Gil, Jesús

    2012-11-01

    Surfacen® is a clinical surfactant preparation of porcine origin, partly depleted of cholesterol, which is widely used in Cuba to treat pre-term babies at risk or already suffering neonatal respiratory distress. In the present study we have characterized the interfacial behavior of Surfacen in several in vitro functional models, including spreading and compression-expansion cycling isotherms in surface balances and in a captive bubble surfactometer, in comparison with the functional properties of whole native surfactant purified from porcine lungs and its reconstituted organic extract, the material from which Surfacen is derived. Surfacen exhibited similar properties to native porcine surfactant or its organic extract to efficiently form stable surface active films at the air-liquid interface, able to consistently reach surface tensions below 5mN/m upon repetitive compression-expansion cycling. Surfacen films, however, showed a substantially larger and stable compression-driven segregation of condensed lipid phases than exhibited by films formed by native surfactant or its organic extract. In spite of structural differences observed at microscopic level, Surfacen membranes showed a similar thermotropic behavior to membranes from native surfactant or its organic extract, characterized by calorimetry or fluorescence spectroscopy of samples doped with the Laurdan probe. On the other hand, analysis by atomic force microscopy of films formed by Surfacen or by the organic extract of native porcine surfactant revealed a similar network of interconnected condensed nanostructures, suggesting that the organization of the films at the submicroscopic level is the essential feature to support the proper stability and mechanical properties permitting the interfacial surfactant films to facilitate the work of breathing. PMID:22771553

  7. Unique influence of cholesterol on modifying the aggregation behavior of surfactant assemblies: investigation of photophysical and dynamical properties of 2,2'-bipyridine-3,3'-diol, BP(OH)2 in surfactant micelles, and surfactant/cholesterol forming vesicles.

    PubMed

    Ghosh, Surajit; Kuchlyan, Jagannath; Roychowdhury, Subhajit; Banik, Debasis; Kundu, Niloy; Roy, Arpita; Sarkar, Nilmoni

    2014-08-01

    The binding and rotational properties of an excited-state intramolecular proton transfer (ESIPT) fluorophore, 2,2'-bipyridine-3,3'-diol, BP(OH)2 has been investigated in alkyltrimethylammonium bromide containing (CnTAB, n = 12, 14, and 16) micelles and alkyltrimethylammonium bromide/cholesterol (CnTAB (n = 14 and 16)/cholesterol) forming vesicles using fluorescence-based spectroscopy techniques. The formation of thermodynamically stable unilamellar self-assemblies of alkyltrimethylammonium bromide/cholesterol are characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements. Individually, aqueous solutions of all these alkyltrimethylammonium bromide form micelles after certain surfactant concentration (critical micelle concentration, cmc) of surfactant, whereas cholesterol molecules are insoluble in water. But with the variation of the cholesterol-to-surfactant molar ratio (Q = [cholesterol]/[surfactant]), uniform distribution of vesicular aggregates in aqueous solution can be obtained. The micelle-to-vesicle transition of surfactant solution upon addition of cholesterol also influences the steady state emission profile, fluorescence lifetime, and rotational dynamics of BP(OH)2 molecule. The diketo tautomer of BP(OH)2 molecule gets stabilized as the concentration of surfactant increases in aqueous solution. Fluorescence lifetime and rotational time constant of the BP(OH)2 molecule are also influenced by the variation of alkyl chain length of surfactant molecule. The emission quantum yield (?) is also found to be sensitive with surfactant concentration, variation in chain length of surfactants, and it saturates after the cmc of surfactants. The rigid and restricted microenvironment of vesicle bilayer enhance the lifetime and also rotational relaxation of BP(OH)2 significantly. The rotational behavior of BP(OH)2 in surfactant/cholesterol self-assemblies is also explained by using analytical parameters related to time-resolved anisotropy following two-step process and wobbling in a cone models. PMID:25036947

  8. Effect of Additives on the Dynamic Behavior of Surfactants in Solution

    Microsoft Academic Search

    Milindkumar S. Kalekar; Sunil S. Bhagwat

    2007-01-01

    Effect of organic additives on the dynamic behavior of surfactant in solution was studied using the maximum bubble pressure method. Dynamic surface tension of solution of sodium lauryl sulphate (SLS) was measured at different concentrations with various additives. Additives such as lauric acid diethanol amide (LDEA), cocoamidopropyl betaine (CAPB), lauryl amido propyl betaine (LAPB), and lauryl amido propyl amine oxide

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

    PubMed

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

    2009-08-01

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

  10. Interfacial structural role of pH-shifting processed pea protein in the oxidative stability of oil/water emulsions.

    PubMed

    Jiang, Jiang; Zhu, Bo; Liu, Yuanfa; Xiong, Youling L

    2014-02-19

    Understanding the behavior of protein surfactants at the oil-water interface is essential to the design of physicochemically stable emulsions. The objective of the study was to investigate the steric role of an interfacial membrane made of structurally modified pea protein with alkaline pH treatment (APP) in the oxidative stability of oil-in-water emulsions. Confocal laser scanning microscopy depicted more uniform and smaller oil droplets that had a reduced tendency to coalesce for emulsions prepared with APP than with native pea protein (NPP). Correspondingly, the APP emulsions were less prone to oxidation (malonaldehyde, peroxide) during storage. Similarly, cryo-transmission electron microscopy revealed more uniform air pockets with smoother undersurface that were surrounded by partially coalesced emulsions in whipped creams prepared with APP than with NPP. The improved interfacial properties and steric hindrance played a crucial role in the inhibition of oxidation in emulsions by alkaline pH-modified pea protein. PMID:24460504

  11. Effects of urea on the microstructure and phase behavior of aqueous solutions of polyoxyethylene surfactants

    PubMed Central

    Bianco, Carolina L.; Schneider, Craig S.; Santonicola, Mariagabriella; Lenhoff, Abraham M.; Kaler, Eric W.

    2010-01-01

    Membrane proteins are made soluble in aqueous buffers by the addition of various surfactants (detergents) to form so-called protein-detergent complexes (PDCs). Properties of membrane proteins are commonly assessed by unfolding the protein in the presence of surfactant in a buffer solution by adding urea. The stability of the protein under these conditions is then monitored by biophysical methods such as fluorescence or circular dichroism spectroscopy. Often overlooked in these experiments is the effect of urea on the phase behavior and micellar microstructure of the different surfactants used to form the PDCs. Here the effect of urea on five polyoxyethylene surfactants – n-octylytetraoxyethylene (C8E4), n-octylpentaoxyethylene (C8E5), n-decylhexaoxyethylene (C10E6), n-dodecylhexaoxyethylene (C12E6) and n-dodecyloctaoxylethylene (C12E8) – is explored. The presence of urea increases the critical micelle concentration (CMC) of all surfactants studied, indicating that the concentration of both the surfactant and urea should be considered in membrane protein folding studies. The cloud point temperature of all surfactants studied also increases with increasing urea concentration. Small-angle neutron scattering shows a urea-induced transition from an elongated to a globular shape for micelles of C8E4 and C12E6. In contrast, C8E5 and C12E8 form more globular micelles at room temperature and the micelles remain globular as the urea concentration is increased. The effects of increasing urea concentration on micelle structure are analogous to those of decreasing the temperature. The large changes in micelle structure observed here could also affect membrane protein unfolding studies by changing the structure of the PDC. PMID:21359094

  12. Interfacial properties in solid-stabilized emulsions

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

    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.

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

    PubMed

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

    2014-07-01

    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

  14. Surfactant Effects on the Morphology and Pseudocapacitive Behavior of V2 O5 ?H2 O.

    PubMed

    Qian, Aniu; Zhuo, Kai; Shin, Myung Sik; Chun, Woo Won; Choi, Bit Na; Chung, Chan-Hwa

    2015-07-20

    To overcome the drawback of low electrical conductivity within supercapacitor applications, several surfactants are used for nanoscale V2 O5 to enhance the specific surface area. Polyethylene glycol 6000 (PEG-6000), sodium dodecylbenzene sulfonate (SDBS), and Pluronic P-123 (P123) controllers, if used as soft templates, easily form large specific surface area crystals. However, the specific mechanism through which this occurs and the influence of these surfactants is not clear for V2 O5 ?H2 O. In the present study, we aimed to investigate the mechanism of crystal growth through hydrothermal processes and the pseudocapacitive behavior of these crystals formed by using diverse surfactants, including PEG-6000, SDBS, and P123. Our results show that different surfactants can dramatically influence the morphology and capacitive behavior of V2 O5 ?H2 O powders. Linear nanowires, flower-like flakes, and curly bundled nanowires can be obtained because of electrostatic interactions in the presence of PEG-6000, SDBS, and P123, respectively. Furthermore, the electrochemical performance of these powders shows that the nanowires, which are electrodes mediated by PEG-6000, exhibit the highest capacitance of 349?F?g(-1) at a scan rate of 5?mV?s(-1) of all the surfactants studied. However, a symmetric P123 electrode comprising curly bundled nanowires with numerous nanopores showed an excellent and stable specific capacitance of 127?F?g(-1) after 200?cycles. This work is beneficial to understanding the fundamental role of the surfactant in the assisted growth of V2 O5 ?H2 O and the resulting electrochemical properties of the pseudocapacitors, which could be useful for the future design of appropriate materials. PMID:25711651

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

    PubMed

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

    2009-07-30

    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

  16. Phase and rheological behavior of the polymerizable surfactant CTAVB and water.

    PubMed

    Soltero, J F A; Alvarez-Ramírez, J G; Fernández, V V A; Tepale, N; Bautista, F; Macías, E R; Pérez-López, J H; Schulz, P C; Manero, O; Solans, C; Puig, J E

    2007-08-01

    The phase and rheological behaviors of the polymerizable surfactant, cetyltrimethylammonium benzoate (CTAVB), and water as a function of surfactant concentration and temperature are investigated here. The critical micelle concentration (cmc) and the (cmc(2)), as well as the Krafft temperature (T(K)), are reported. A large highly viscous micellar solution region and hexagonal- and lamellar-phase regions were identified. The micellar solutions exhibit shear thickening in the dilute regime, below the overlapping or entanglement concentration. At higher concentrations, wormlike micelles form and the solutions show strong viscoelasticity and Maxwell behavior in the linear regime and shear banding flow in the nonlinear regime. The linear viscoelastic regime is analyzed with the Granek-Cates model, showing that the relaxation is controlled by the kinetics of reformation and scission of the micelles. The steady and unsteady responses in the nonlinear regime are compared with the predictions of the Bautista-Manero-Puig (BMP) model. Model predictions follow the experimental data closely. PMID:17547934

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

    SciTech Connect

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

    1991-04-18

    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.

  18. Aggregation behavior and complex structure between triblock copolymer and anionic surfactants

    Microsoft Academic Search

    Yiming Li; Mutai Bao; Zhining Wang; Haixia Zhang; Guiying Xu

    2011-01-01

    The aggregation behavior and complex structure of ABA triblock copolymer EO76PO30EO76 (F68) with sodium dodecyl sulfate (SDS) and sodium bis(2-ethylhexyl)sulfonate (AOT) in aqueous solution were investigated by surface tension, fluorescence techniques and dynamic light-scattering (DLS) measurements. It is revealed that in certain regions of binding, surfactant\\/F68 complexes are formed. Structural informations and size of complexes are evaluated. When F68 is

  19. Experimental Characterization of Canola Oil Emulsion Combustion in a Modified Furnace

    E-print Network

    Bhimani, Shreyas Mahesh

    2012-07-16

    , the surfactant is called an anionic surfactant and if the charge is positive, it is called a cationic surfactant. There are surfactants whose heads have two oppositely charged groups. They are referred to as zwitterionic/amphoteric surfactants. 2. Nonionic... oil emulsion with 2% surfactant (w/w)] and 85-12.5 emulsion [12.5% methanol ? in ? 85% canola oil (w/w) emulsion with 2.5% surfactant]. All the combustion experiments were conducted for a constant heat output of 72,750 kJ/hr. One of the major...

  20. Effect of the spacer length on the association and adsorption behavior of dissymmetric gemini surfactants.

    PubMed

    Sikiri?, M; Primozic, I; Talmon, Y; Filipovi?-Vincekovi?, N

    2005-01-15

    A series of dissymmetric gemini surfactants with the general formula [C12H25(CH3)2N(CH2)sN(CH3)2C14H29]Br2 designed as 12-s-14, where s=2, 6, and 10, were synthesized and their physicochemical properties investigated. The effect of spacer length on Krafft temperature, adsorption at the air/solution interface, and association in aqueous solution was studied by tensiometry, conductometry, and cryo-transmission electron microscopy. The Krafft temperature was found to increase linearly with spacer length. In the submicellar concentration range the dissymmetric 12-s-14 surfactants display ion pairing and premicellar association. Adsorption at air/solution interfaces and micellization in aqueous solution are similar to the behavior of their symmetric counterparts and depend strongly on spacer length. PMID:15571705

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

    SciTech Connect

    P. Somasundaran

    2004-11-20

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

  2. Influence of surfactant amphiphilicity on the phase behavior of IL-based microemulsions.

    PubMed

    Harrar, Agnes; Zech, Oliver; Klaus, Angelika; Bauduin, Pierre; Kunz, Werner

    2011-10-15

    In this work, we report on the phase behavior of 1-ethyl-3-methyl-imidazolium-ethylsulfate ([emim][etSO(4)])/limonene/polyethylene glycol tert-octylphenyl ether (Triton X-114 or TX-114) microemulsions as a function of ionic liquid (IL) content and temperature. Phase diagrams, conductivity measurements, and small angle X-ray scattering (SAXS) experiments will be presented. A hydrophilic IL, instead of water is used with the goal to enlarge the temperature range on which stable microemulsions can be formed. Indeed, the system shows remarkably large temperature stability, in particular down to -35 °C. We will emphasize on a comparison with a recently published work about microemulsions composed of [emim][etSO(4)], limonene, and Triton X-100 that to some extent are stable at temperatures well below the freezing point of water. The key parameter responsible for the difference in phase behavior, microstructure, and temperature stability is the average repeating number of ethylene oxide units in the surfactant head group, which is smaller for Triton X-114 compared to Triton X-100. Among the fundamental interest, how the amphiphilicity of the surfactant influences the phase diagram and phase behavior of IL-based microemulsions, the exchange of Triton X-100 by Triton X-114 results in one main advantage: along the experimental path the temperature where phase segregation occurs is significantly lowered leading to single phase microemulsions that exist at temperatures beneath 0 °C. PMID:21784427

  3. Dimeric (Gemini) Surfactants: Effect of the Spacer Group on the Association Behavior in Aqueous Solution

    Microsoft Academic Search

    Raoul Zana

    2002-01-01

    Dimeric (gemini) surfactants are made up of two amphiphilic moieties connected at the level of, or very close to, the head groups by a spacer group of varying nature: hydrophilic or hydrophobic, rigid or flexible. These surfactants represent a new class of surfactants that is finding its way into surfactant-based formulations. The nature of the spacer group (length, flexibility, chemical

  4. Models of gemini surfactants

    E-print Network

    Haim Diamant; David Andelman

    2003-02-10

    Gemini (dimeric) surfactants are composed of two monomeric surfactant molecules linked by a spacer chain. Their self-assembly behavior differs qualitatively from that of monomeric surfactants. We review the various theoretical attempts to account for the behavior of this new class of amphiphilic molecules.

  5. Crossover in the wetting behavior at surfactant-laden liquid-crystal-water interfaces: Experiment and theory

    NASA Astrophysics Data System (ADS)

    Kadivar, Erfan; Bahr, Christian; Stark, Holger

    2007-06-01

    The behavior of a nematic liquid crystal at a surfactant-laden interface to an aqueous phase is studied under the condition of homeotropic anchoring. It is shown that with decreasing surfactant concentration the system shifts from surface-enhanced to surface-decreased order, i.e., the behavior changes from complete nematic wetting when the nematic-isotropic phase transition is approached from above to a different wetting behavior below the transition, characterized by a considerably decreased Maier-Saupe order parameter at the interface. The experimental behavior is analyzed within the framework of the Landau-de Gennes theory supplemented by a surface free energy, in which the wetting behavior is controlled by the magnitude of the anchoring strength and the preferred surface order parameter in comparison to the bulk order parameter. The theoretical modeling is able to account for all experimental observations.

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

    PubMed

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

    2013-08-30

    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

  7. Stabilisation of emulsions using hydrophobically modified inulin (polyfructose)

    Microsoft Academic Search

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

    2004-01-01

    Oil-in-water (O\\/W) emulsions were prepared using a hydrophobically modified inulin surfactant, INUTEC®SP1. The quality of the emulsions was evaluated using optical microscopy. Emulsions, prepared using INUTEC®SP1 alone had large droplets, but this could be significantly reduced by addition of a cosurfactant to the oil phase, namely Span 20. The stability of the emulsions was investigated in water, in 0.5, 1.0

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

    PubMed

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

    2007-11-01

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

  9. Emulsifying properties of legume proteins compared to ?-lactoglobulin and Tween 20 and the volatile release from oil-in-water emulsions.

    PubMed

    Benjamin, O; Silcock, P; Beauchamp, J; Buettner, A; Everett, D W

    2014-10-01

    The emulsifying properties of plant legume protein isolates (soy, pea, and lupin) were compared to a milk whey protein, ?-lactoglobulin (?-lg), and a nonionic surfactant (Tween 20). The protein fractional composition was characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. The following emulsion properties were measured: particle diameter, shear surface ?-potential, interfacial tension (IT), and creaming velocity. The effect of protein preheat treatment (90 °C for 10 min) on the emulsifying behavior and the release of selected volatile organic compounds (VOCs) from emulsions under oral conditions was also investigated in real time using proton transfer reaction-mass spectrometry. The legume proteins showed comparable results to ?-lg and Tween 20, forming stable, negatively charged emulsions with particle diameter d3,2 < 0.4 ?m, and maintained stability over 50 d. The relatively lower stability of lupin emulsions was significantly correlated with the low protein surface hydrophobicity and IT of the emulsion. After heating the proteins, the droplet size of pea and lupin emulsions decreased. The VOC release profile was similar between the protein-stabilized emulsions, and greater retention was observed for Tween 20-stabilized emulsions. This study demonstrates the potential application of legume proteins as alternative emulsifiers to milk proteins in emulsion products. PMID:25212592

  10. The sorption behavior of complex pollution system composed of aldicarb and surfactant--SDBS.

    PubMed

    Dai, S; Liu, G; Qian, Y; Cheng, X

    2001-06-01

    The behavior of complex pollution system in soil composed of aldicarb, a carbamate pesticide, and sodium dodecylbenzenesulfonate (SDBS), an anionic surfactant, was studied by the experiment of shaking sorption balance. The range of concentration of aldicarb and SDBS was 0.4-5.0 and 1-1000 mg/kg of dried soil, respectively. Linear sorption isotherm was well fitted for these two chemicals. SDBS can decrease the sorption of aldicarb in soil remarkably. While the concentration of SDBS increased from 0 to 1000 mg/kg, the linear sorption coefficient can be decreased by 50%. But aldicarb showed no effect on the sorption of SDBS in experiment. In addition the mechanism of the effect of SDBS on sorption of aldicarb was discussed. PMID:11358309

  11. Cyclodextrin stabilised emulsions and cyclodextrinosomes.

    PubMed

    Mathapa, Baghali G; Paunov, Vesselin N

    2013-11-01

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

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

    PubMed Central

    2009-01-01

    Colloidal nanodispersions of ZnS have been prepared using aqueous micellar solution of two cationic surfactants of trimethylammonium/pyridinium series with different head groups i.e., cetyltrimethylammonium chloride (CTAC) and cetyltrimethylpyridinium chloride (CPyC). The role of these surfactants in controlling size, agglomeration behavior and photophysical properties of ZnS nanoparticles has been discussed. UV–visible spectroscopy has been carried out for determination of optical band gap and size of ZnS nanoparticles. Transmission electron microscopy and dynamic light scattering were used to measure sizes and size distribution of ZnS nanoparticles. Powder X-ray analysis (Powder XRD) reveals the cubic structure of nanocrystallite in powdered sample. The photoluminescence emission band exhibits red shift for ZnS nanoparticles in CTAC compared to those in CPyC. The aggregation behavior in two surfactants has been compared using turbidity measurements after redispersing the nanoparticles in water. In situ evolution and growth of ZnS nanoparticles in two different surfactants have been compared through time-dependent absorption behavior and UV irradiation studies. Electrical conductivity measurements reveal that CPyC micelles better stabilize the nanoparticles than that of CTAC. PMID:20596462

  13. Molecular interactions at the hexadecane/water interface in the presence of surfactants studied with second harmonic generation.

    PubMed

    Sang, Yajun; Yang, Fangyuan; Chen, Shunli; Xu, Hongbo; Zhang, Si; Yuan, Qunhui; Gan, Wei

    2015-06-14

    It is important to investigate the influence of surfactants on structures and physical/chemical properties of oil/water interfaces. This work reports a second harmonic generation study of the adsorption of malachite green (MG) on the surfaces of oil droplets in a hexadecane/water emulsion in the presence of surfactants including sodium dodecyl sulfate, polyoxyethylene-sorbitan monooleate (Tween80), and cetyltrimethyl ammonium bromide. It is revealed that surfactants with micromolar concentrations notably influence the adsorption of MG at the oil/water interface. Both competition adsorption and charge-charge interactions played very important roles in affecting the adsorption free energy and the surface density of MG at the oil/water interface. The sensitive detection of the changing oil/water interface with the adsorption of surfactants at such low concentrations provides more information for understanding the behavior of these surfactants at the oil/water interface. PMID:26071724

  14. Molecular interactions at the hexadecane/water interface in the presence of surfactants studied with second harmonic generation

    NASA Astrophysics Data System (ADS)

    Sang, Yajun; Yang, Fangyuan; Chen, Shunli; Xu, Hongbo; Zhang, Si; Yuan, Qunhui; Gan, Wei

    2015-06-01

    It is important to investigate the influence of surfactants on structures and physical/chemical properties of oil/water interfaces. This work reports a second harmonic generation study of the adsorption of malachite green (MG) on the surfaces of oil droplets in a hexadecane/water emulsion in the presence of surfactants including sodium dodecyl sulfate, polyoxyethylene-sorbitan monooleate (Tween80), and cetyltrimethyl ammonium bromide. It is revealed that surfactants with micromolar concentrations notably influence the adsorption of MG at the oil/water interface. Both competition adsorption and charge-charge interactions played very important roles in affecting the adsorption free energy and the surface density of MG at the oil/water interface. The sensitive detection of the changing oil/water interface with the adsorption of surfactants at such low concentrations provides more information for understanding the behavior of these surfactants at the oil/water interface.

  15. On the transport of emulsions in porous media

    SciTech Connect

    Cortis, Andrea; Ghezzehei, Teamrat A.

    2007-06-27

    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.

  16. Microwave-assisted modification on montmorillonite with ester-containing Gemini surfactant and its adsorption behavior for triclosan.

    PubMed

    Liu, Bo; Lu, Junxiang; Xie, Yu; Yang, Bin; Wang, Xiaoying; Sun, Runcang

    2014-03-15

    To obtain effective adsorbent that can remove emerging organic pollutant of triclosan (TCS) in aquatic environment, different ester-containing Gemini surfactant-modified MMT (EMMT) were prepared under microwave irradiation. The whole process was rapid, uniform, easy and energy-efficient. The structures and morphology of EMMT were characterized by XRD, TEM, FT-IR, SEM and TGA. The results revealed that the saturated intercalation amount of this surfactant was 0.8 times to cation exchange capacity (CEC) of MMT, and there was electrostatic interaction between ester-containing Gemini surfactant and MMT. In addition, they bound in the ways of intercalation, intercalation-adsorption or adsorption, which relied on the dosage of the surfactant. The surface of EMMT was hydrophobic, rough and fluffy, which contributed to its strong adsorption capacity. The adsorption equilibrium data of EMMT for TCS were fitted to Langmuir and Freundlich isothermal adsorption model. The result showed that Langmuir isothermal adsorption model could describe the adsorption behavior better, the adsorption behavior of TCS on EMMT was confirmed to a surface monolayer adsorption, and notably the theoretical maximum adsorption capacity was up to 133 mg/g. Therefore, this work lays important foundation on developing effective and safe absorbent materials for the treatment of emerging organic pollutants. PMID:24461850

  17. The phase behavior of lipid monolayers containing pulmonary surfactant protein C studied by fluorescence light microscopy

    Microsoft Academic Search

    Anja von Nahmen; Andreas Post; Hans-Joachim Galla; Manfred Sieber

    1997-01-01

    Three compounds of the pulmonary surfactant – dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylglycerol (DPPG),\\u000a and the surfactant associated protein C (SP-C) – were spread at the air-water interface of a Langmuir trough as a model system\\u000a to mimic the properties of natural surfactant. Fluorescence microscopical images of the film formed at the interface were\\u000a obtained during compression using a fluorescence dye bound covalently

  18. Microemulsion phase behavior of anionic-cationic surfactant mixtures: Effect of tail branching

    Microsoft Academic Search

    A. Upadhyaya; E. J. Acosta; J. F. Scamehorn; D. A. Sabatini

    2006-01-01

    This research evaluated middle-phase microemulsion formation by varying the mole ratio of anionic and cationic surfactants\\u000a in mixtures with four different oils (trichloroethylene, n-hexane, limonene, and n-hexadecane). Mixtures of a double-tailed anionic surfactant (sodium dihexyl sulfosuccinate, SDHS) and an unbalanced-tail\\u000a (i.e., doubletailed with tails of different length) cationic surfactant (benzethonium chloride, BCl) were able to form microemulsions\\u000a without alcohol addition.

  19. An investigation of the behavior of radioactivated surfactants in linear, unconsolidated sand systems

    E-print Network

    Rivero, Ramon T

    1964-01-01

    )3 Antara Chemicals 414. 37 Atlantic Hefining Naprofix 563 Na lauryl Sulfate CIIH 23C-S03Na Onyx Chemical Co. 287, 45 (Continued) TABLE III - PHYSICAL AND CHEMICAL INFORMATION GN SURFACTANTS (Part 1 - Cant. ) Surf'actant No. Trade Name Chemical Name...

  20. An investigation of the behavior of radioactivated surfactants in linear, unconsolidated sand systems 

    E-print Network

    Rivero, Ramon T

    1964-01-01

    )3 Antara Chemicals 414. 37 Atlantic Hefining Naprofix 563 Na lauryl Sulfate CIIH 23C-S03Na Onyx Chemical Co. 287, 45 (Continued) TABLE III - PHYSICAL AND CHEMICAL INFORMATION GN SURFACTANTS (Part 1 - Cant. ) Surf'actant No. Trade Name Chemical Name...

  1. Mathematical modeling of a water-in-oil emulsion droplet behavior under the microwave impact

    NASA Astrophysics Data System (ADS)

    Fatkhullina, Y. I.; Musin, A. A.; Kovaleva, L. A.; Akhatov, I. S.

    2015-01-01

    The problem of microwave (MW) electromagnetic radiation impact on a single water-in-oil droplet is considered. The system of heat equations within the droplet and in the surrounding liquid, incompressible Navier-Stokes equations within the droplet and in the surrounding liquid, and equation of state are considered. The formulated problem is solved numerically using TDMA (Tri-diagonal-matrix algorithm), SIMPLE algorithm and VOF method (volume of fluid method for the dynamics of free boundaries) in Euler coordinates. The results in the form of the dependence of the temperature within the droplet and in the surrounding liquid on the time of microwave impact and streamlines thermal convection are represented; dependence of the velocity of droplet's moving on the power of the of the microwave impact is shown. The obtained results can help to establish criteria for the efficient applicable of the microwave method for the water-in-oil emulsions destruction.

  2. Relation between viscosity and stability for heavy oil emulsions

    E-print Network

    Ye, Sherry Qianwen

    1998-01-01

    The relation between viscosity and stability has been hics. found by investigating the effect of surfactant concentration on emulsion stability. Based on the Bingham plastic model for viscosity as a function of shear rate, two parameters were found...

  3. SODIUM LIGNIN SULFONATE TO STABILIZE HEAVY CRUDE OIL-IN-WATER EMULSIONS FOR PIPELINE TRANSPORTATION

    Microsoft Academic Search

    NAEL N. ZAKI; NEHAL S. AHMED; AMAL M. NASSAR

    2000-01-01

    The efficiency of sodium lignin sulfonate (SLS) as an anionic surfactant derived from waste wood pulping industry in stabilizing an Egyptian heavy crude oil (Geisum)-in-water emulsions for pipeline transportation has been investigated. The stability and rheology of the emulsions stabilized by SLS or with a nonionic surfactant nonyl phenol diethylenetriamine formaldehyde ethoxylate (NDFE) individually or in a mixture have been

  4. Influence of three synthetic membranes on the release of caffeine from concentrated W\\/O emulsions

    Microsoft Academic Search

    Pascale Clément; Cécile Laugel; Jean-Paul Marty

    2000-01-01

    We measured the release rate characteristics of caffeine from concentrated emulsions using three different sources of synthetic membranes. The formulations tested included, on the one hand, two stable cosmetic concentrated W\\/O emulsions (90% w\\/w) — one with a non ionic surfactant and one with a silicone surfactant — and on the other hand, a commercially available hydroalcoholic gel. All formulations

  5. Hydrophobically Modified Halloysite Nanotubes as Reverse Micelles for Water-in-Oil Emulsion.

    PubMed

    Cavallaro, Giuseppe; Lazzara, Giuseppe; Milioto, Stefana; Parisi, Filippo

    2015-07-14

    An easy strategy to obtain inorganic reverse micelles based on halloysite nanotubes (HNTs) and alkyltrimethylammonium bromides has been developed. The selective modification of the HNTs external surface with cationic surfactants endows to generate tubular nanostructures with a hydrophobic shell and a hydrophilic cavity. The influence of the surfactants alkyl chain on the HNTs functionalization degree has been investigated. The dynamic behavior of the surfactant/HNT hybrids in solvents with variable polarity has been correlated to their affinity toward hydrophobic media explored through partition experiments. The water-in-oil emulsion is able to solubilize copper sulfate, proving the incorporation and the loading of hydrophilic compounds into the HNTs lumen. Here we have fabricated ecocompatible reverse micelles with tunable hydrophobic/hydrophilic interface that might be suitable for industrial and biological applications as well as for selective organic synthesis. PMID:26119491

  6. Physicochemical behaviors of cationic gemini surfactant (14-4-14) based microheterogeneous assemblies.

    PubMed

    Das, Sibani; Mukherjee, Indrajyoti; Paul, Bidyut K; Ghosh, Soumen

    2014-10-28

    A comprehensive study of micellization and microemulsion formation of a cationic gemini surfactant (tetramethylene-1,4-bis(dimethyltetradecylammonium bromide; 14-4-14) in the absence or presence of hydrophobically modified polyelectrolyte, sodium carboxymethylcellulose (NaCMC), has been conducted by conductometry, tensiometry, microcalorimetry, and fluorimetry methods at different temperatures. Both critical micelle concentration and degree of ionization of the surfactant have been observed to increase with increasing temperature. The interfacial and thermodynamic parameters were evaluated. The standard Gibbs free energy of micellization (?Gm°) is negative, which decreases with increase in temperature. Larger entropic contribution is observed compared to the enthalpy. The interaction of 14-4-14 with NaCMC produces coacervates which was determined from turbidimetry method. The pseudoternary phase behavior of the microemulsion systems comprising water (or NaCMC as additive), 14-4-14, isopropanol (IP) or n-butanol (Bu) as cosurfactant, and isopropyl myristate (IPM) were studied at 298 K. Phase diagrams reveal that IP derived microemulsions (in the absence of NaCMC) offer a large isotropic region compared to Bu-derived systems at comparable physicochemical conditions. Increasing the concentration of IP or Bu decreases the isotropic region in the phase diagram. NaCMC influences the microemulsion zone, depending upon its concentration, and type of cosurfactant and surfantant/cosurfactant ratio. Dynamic light scattering and conductometric measurements show the size of the droplet, threshold temperature of percolation, scaling parameters, and activation energy of the percolation process of 14-4-14/IP or Bu derived microemulsion systems without/with NaCMC at various physicochemical conditions. Bu exerts a greater effect to reduce ?t than IP as a cosurfactant (in the absence of NaCMC) at comparable ?. On the other hand, IP showed better percolating effect than Bu in the presence of NaCMC. Bu and IP (as cosurfactant) and NaCMC (as additive) influenced the microemulsion droplet size (Dh) to different extents under comparable conditions. Temperature insensitive microemulsions have been reported at the studied temperature range (298–353 K). 14-4-14/IP (1:2)-derived microemulsion showed a fractured surface at fixed ? = 15, where ? is the water and surfactant molar ratio, and temperature (298 K); whereas, large scale mesospheres comprising multiple closely winded nanoslices and spheroid morphology were formed in 14-4-14/IP and 14-4-14/Bu microemulsions, respectively, in the presence of 0.01 g % NaCMC, at comparable conditions. These systems revealed good antimicrobial activity toward the strains of Gram-positive Bacillus subtilis and Gram-negative Escherichia coli bacteria at 298 K, and inhibitory effect was governed by ?, type of cosurfactant, and bacterial strains. PMID:25241843

  7. Variation in emulsion stabilization behavior of hybrid silicone polymers with change in molecular structure: Phase diagram study

    Microsoft Academic Search

    Somil C. Mehta; P. Somasundaran; Ravi Kulkarni

    2009-01-01

    Silicone oils are widely used in cosmetics and personal care applications to improve softness and condition skin and hair. Being insoluble in water and most hydrocarbons, a common mode of delivering them is in the form of emulsions. Currently most applications use polyoxyethylene (non-ionic) modified siloxanes as emulsifiers to stabilize silicone oil emulsions. However, ionically grafted silicone polymers have not

  8. Influence of interfacial rheology on foam and emulsion properties

    Microsoft Academic Search

    D Langevin

    2000-01-01

    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

  9. Zero-Valent Metal Emulsion for Reductive Dehalogenation of DNAPLS

    NASA Technical Reports Server (NTRS)

    Reinhart, Debra R. (Inventor); Clausen, Christian (Inventor); Geiger, Cherie L. (Inventor); Quinn, Jacqueline (Inventor); Brooks, Kathleen (Inventor)

    2003-01-01

    A zero-valent metal emulsion is used to dehalogenate solvents, such as pooled dense non-aqueous phase liquids (DNAPLs), including trichloroethylene (TCE). The zero-valent metal emulsion contains zero-valent metal particles, a surfactant, oil and water. The preferred zero-valent metal particles are nanoscale and microscale zero-valent iron particles

  10. DEMULSIFICATION OF WATER IN OIL EMULSIONS USING WATER SOLUBLE DEMULSIFIERS

    Microsoft Academic Search

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

    1992-01-01

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

  11. Zero-Valent Metal Emulsion for Reductive Dehalogenation of DNAPLs

    NASA Technical Reports Server (NTRS)

    Reinhart, Debra R. (Inventor); Clausen, Christian (Inventor); Gelger, Cherie L. (Inventor); Quinn, Jacqueline (Inventor); Brooks, Kathleen (Inventor)

    2006-01-01

    A zero-valent metal emulsion is used to dehalogenate solvents, such as pooled dense non-aqueous phase liquids (DNAPLs), including trichloroethylene (TCE). The zero-valent metal emulsion contains zero-valent metal particles, a surfactant, oil and water, The preferred zero-valent metal particles are nanoscale and microscale zero-valent iron particles.

  12. Tuning Lyotropic Liquid Crystalline Phase Behavior of Gemini Surfactants by Linker Parity

    NASA Astrophysics Data System (ADS)

    Perroni, Dominic; Baez-Cotto, Carlos; Mantha, Sriteja; Sorenson, Gregory; Yethiraj, Arun; Mahanthappa, Mahesh

    2015-03-01

    Aqueous bicontinuous lyotropic liquid crystals (LLCs) derived from small molecule surfactants are useful nanostructured materials with myriad applications, in fields ranging from structural biology to membrane science. However, access to these coveted phases is limited by the fact that few surfactant platforms readily stabilize these network phases over the wide amphiphile concentration and temperature phase windows necessary for their widespread applications. We have recently shown that gemini (``twin tail'') dicarboxylate surfactants, comprising two single tail amphiphiles covalently linked near the headgroup by a hydrophobic bridge, exhibit a greatly increased propensity to form stable double gyroid LLC phases. In this presentation, we will demonstrate the unusual sensitivity of gemini dicarboxylate surfactant lyotropic self-assembly to the length of the hydrophobic bridge: odd-carbon linkers produce stable double gyroid phases over amphiphile composition windows as wide as 40 wt% that are stable between T = 22-100 °C. We rationalize these results in terms of the detailed molecular conformations of the surfactants that stem from the length of the bridging moiety, which suggests that this molecular design strategy may generally extend to other surfactant classes.

  13. Spreading of Emulsions on Glass Substrates

    NASA Astrophysics Data System (ADS)

    Mohammad Karim, Alireza; Kavehpour, Pirouz

    2012-11-01

    The wettability of emulsions is an important factor with explicit influence in an extensive variety of industrial applications ranging from the petroleum to food industries. Surprisingly, there is no comprehensive study of emulsion spreading to date; this is due to the complexity of the structure of the emulsions and non-homogeneity of the dispersed phase bubbles in size as well as distribution through the emulsion. The spreading of water/silicone oil emulsions on glass substrates was investigated. The emulsions were prepared with varying volume fractions of water dispersed in silicone oil, with addition of small amounts of surfactant to stabilize the emulsion structure. The time dependent variation of dynamic contact angle, base diameter, and the spreading rate of the droplets of an emulsion are different from a pure substance. The effect of water/silicone oil weight percentage as well as the droplet size and dispersed phase bubble size were also investigated. The weight percentage of water/silicone oil emulsion and droplet size did not have significant influence on the spreading dynamics; however the dispersed phase drop size affected the spreading dynamics substantially.

  14. Mixed surfactant systems for enhanced oil recovery

    SciTech Connect

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

    1990-12-01

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

  15. Preparation of emulsions by rotor-stator homogenizer and ultrasonic cavitation for the cosmeceutical industry.

    PubMed

    Han, Ng Sook; Basri, Mahiran; Abd Rahman, Mohd Basyaruddin; Abd Rahman, Raja Noor Zaliha Raja; Salleh, Abu Bakar; Ismail, Zahariah

    2012-01-01

    Oil-in-water (O/W) nanoemulsions play an important key role in transporting bioactive compounds into a range of cosmeceutical products to the skin. Small droplet sizes have an inherent stability against creaming, sedimentation, flocculation, and coalescence. O/W emulsions varying in manufacturing process were prepared. The preparation and characterization of O/W nanoemulsions with average diameters of as low as 62.99 nm from palm oil esters were carried out. This was achieved using rotor-stator homogenizer and ultrasonic cavitation. Ultrasonic cell was utilized for the emulsification of palm oil esters and water in the presence of mixed surfactants, Tween 80 and Span 80 emulsions with a mean droplet size of 62.99 nm and zeta potential value at -37.8 mV. Results were comparable with emulsions prepared with rotor-stator homogenizer operated at 6000 rpm for 5 min. The stability of the emulsions was evaluated through rheology measurement properties. This included non-Newtonian viscosity, elastic modulus G', and loss modulus G?. A highly stable emulsion was prepared using ultrasonic cavitation comprising a very small particle size with higher zeta potential value and G' > G? demonstrating gel-like behavior. PMID:23089355

  16. Aggregation behavior of SDS/CTAB catanionic surfactant mixture in aqueous solution and at the air/water interface.

    PubMed

    Tah, Bidisha; Pal, Prabir; Mahato, Mrityunjoy; Talapatra, G B

    2011-07-01

    Herein, we report the aggregation behavior of catanionic mixtures of the anionic surfactant sodium dodecyl sulfate (SDS) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) in solution and at the air/water interface obtained by the Langmuir-Blodgett (LB) technique. We employed Fourier transform infrared spectroscopy, in situ phase-contrast inverted microscopy, scanning electron microscopy, and atomic force microscopy to characterize the systems in solution, at the air/water interface, and in LB films. We found spherical vesicles at the SDS/CTAB ratio of 35/65 in aqueous solution and an ordered aggregated morphology called surface micelles at SDS/CTAB ratios of 35/65 to 65/35 at the air/water interface. Other mixtures (SDS/CTAB = 90/10, 10/90) were found to contain mostly disordered aggregated microstructures. An in situ time-dependent study of surface micelle formation at the air/water interface showed micelle ripening through the fusion of smaller micelles. These micelles were successfully immobilized on a glass substrate by the LB technique. Overall, the study might find application in the fundamental science of the physical chemistry of surfactant systems, as well as in the preparation of drug delivery system. PMID:21675762

  17. Unusual pH-regulated surface adsorption and aggregation behavior of a series of asymmetric gemini amino-acid surfactants.

    PubMed

    Lv, Jing; Qiao, Weihong

    2015-04-01

    A new series of pH-regulated asymmetric amino-acid gemini surfactants N,N'-dialkyl-N,N'-diacetate ethylenediamine (Ace(m)-2-Ace(n)), differing by the asymmetric degree and length of the carbon tails (m = 8 and 10, n = 10, 12, 14, and 16), were synthesized in three steps. On the basis of pKa values obtained by pH titration, surface tension, fluorescence, dynamic light scattering (DLS), and transmission electron microscopy (TEM) measurements were performed to study the surface adsorption and aggregation properties in aqueous Ace(m)-2-Ace(n) solution. The new compounds have higher surface activity and better pH adaptability in comparison with that of symmetric gemini surfactants Ace(n)-2-Ace(n). The molecule behavior of Ace(m)-2-Ace(n) can be adjusted by either the hydrophobic group or the pH. With increasing alkyl chain length, the surface adsorption declines but its ability to form aggregates increases. We find that pH can promote the self-assembly transition of Ace(m)-2-Ace(n) from surfactant monomers to aggregates through protonation between H(+) and the tertiary nitrogen group. TEM data further confirm the pH-regulated molecular self-assembly process and the existence of vesicles at neutral or weak acidic pH. pH-recyclability is found to be reversible by pH-light transmittance recycle tests. PMID:25682717

  18. Compaction of DNA by Gemini Surfactants: Effects of Surfactant Architecture

    Microsoft Academic Search

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

    2002-01-01

    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

  19. Aggregation behaviors of gelatin with cationic gemini surfactant at air\\/water interface

    Microsoft Academic Search

    Dan Wu; Guiying Xu; Yujun Feng; Yiming Li

    2007-01-01

    The dilational rheological properties of gelatin with cationic gemini surfactant 1,2-ethane bis(dimethyl dodecyl ammonium bromide) (C12C2C12) at air\\/water interface were investigated using oscillating barriers method at low frequency (0.005–0.1Hz), which was compared with single-chain surfactant dodecyltrimethyl ammonium bromide (DTAB). The results indicate that the maximum dilational modulus and the film stability of gelatin-C12C2C12 are higher than those of gelatin-DTAB. At

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

    SciTech Connect

    Somasundaran, Prof. P.

    2002-03-04

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

  1. Propylene Glycol and Ethoxylated Surfactant Effects on the Phase Behavior of Water\\/Sucrose Stearate\\/Oil System

    Microsoft Academic Search

    Monzer Fanun

    2007-01-01

    In this work, we studied the phase behavior as function of temperature of water\\/sucrose stearate\\/propylene glycol\\/oil and water\\/sucrose stearate\\/ethoxylated mono?di?glyceride\\/oil systems. The oils were R (+)?limonene, isopropylmyristate, and caprylic?capric triglyceride. It was found that adding propylene glycol and ethoxylated mono?di?glyceride to the water\\/sucrose stearate\\/R (+)?limonene and water\\/sucrose stearate\\/isopropylmyristate systems decreases the temperature and surfactants concentration needed for the formation of

  2. Delaying lipid digestion through steric surfactant Pluronic F68: A novel in vitro approach

    Microsoft Academic Search

    M. Wulff-Pérez; M. J. Gálvez-Ruíz; J. de Vicente; A. Martín-Rodríguez

    2010-01-01

    The objective of this study was to investigate and compare the lipolysis rate of emulsions stabilized with two surfactants of a markedly different nature: an ionic mixture of phospholipids and the almost purely steric surfactant Pluronic F68. We have studied emulsions stabilized with only one of them, and also with mixtures with different proportions of these two emulsifiers. The impact

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

    PubMed

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

    2012-12-11

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

  4. Influence of extraction parameters on dispersity of hydrocarbon emulsions from tar sands

    SciTech Connect

    Nadirov, N.K.; Bishimbaev, V.K.; Burkitbaev, S.M.; Kenzhebaev, A.B.; Khodzhanazarov, A.T.

    1988-05-01

    The dependence of hydrocarbon emulsion particle size distribution on the extraction parameters of temperature, surfactant concentration, and mixing intensity was investigated. The water-bitumen solution, with an organic matter content of 14-17% by weight, was obtained from tar sands of the Iman-Kara deposit and emulsified by vigorous mixing in an aqueous surfactant to promote effective precipitation of the washed sand and clay and to suppress flotation. Emulsion particle size distribution was assessed by laser correlation spectroscopy. Correlation and distribution functions were determined. Higher temperatures were found to promote surfactant activity and stabilize the emulsion; at approximately 80 C, with an emulsion concentration of 8-11%, washing efficiency reached 92-95%. Optimal surfactant concentration was determined to be no higher than approximately 3% by weight and mixer speed was found to be optimal at 2000-2500 rpm. The procedure can be used to optimize equipment efficiency and emulsion quality.

  5. Effects of Soluble Surfactant on Drop Formation

    NASA Astrophysics Data System (ADS)

    Liao, Ying-Chih

    2005-11-01

    Surfactants are routinely used to control the breakup of drops and jets in applications as diverse as emulsion and dispersion formation, ink jet printing, crop spraying, microarraying, and microencapsulation. Dynamics of formation of drops of incompressible Newtonian liquids containing a nonionic alkyl ethyleneoxide surfactant from a tube into air are studied experimentally using high-speed visualization and computationally using finite element analysis (FEA). Surfactant solutions at different concentrations below the critical micelle concentration (cmc) are formed by dissolving the surfactant in either water or mixtures of glycerol and water. In the absence of surfactant, computed results are shown to accord well with earlier predictions made with FEA. When surfactants are present, computed predictions are demonstrated to be in excellent agreement with the new experimental measurements. The effects of surfactant on volumes of primary drops and dynamics of satellite drops are also reported.

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

    SciTech Connect

    Menon, V.B.

    1986-01-01

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

  7. Influence of cholic acid on phase transition, rheological behavior, and microstructures of salt-free catanionic surfactant mixtures.

    PubMed

    Liu, Changcheng; Hao, Jingcheng

    2010-04-01

    The influence of a biosurfactant, cholic acid (CA), on the phase transition, microstructure, and rheological properties of two salt-free catanionic surfactant systems, (i) tetradecyltrimethylammonium laurate (TTAL) vesicular solution and (ii) a mixture solution of tetradecyltrimethylammonium hydroxide (TTAOH)/lauric acid (LA)/H(2)O, was investigated. The TTAL vesicular system remains homogeneous at 25 degrees C up to 9.8 mmol.L(-1) CA. At low concentrations of CA, the addition of CA causes a decrease in the viscosity of TTAL vesicular solutions. Upon further addition, the viscosity increases. When LA is gradually substituted by CA in the TTAOH/LA/H(2)O system with equimolar TTAOH and LA to form the TTAOH/(CA + LA)/H(2)O system, the influence of the molar fraction of CA, x = n(CA)/(n(LA) + n(CA)), on the phase transition and rheological behavior was also investigated. With increasing x, the system changes from a birefringent L(alpha) phase of equimolar TTAOH and LA into an L(1)/L(alpha) double-phase, and a single L(1) phase. In the birefringent L(alpha) phase of x = 0.2, cryo-TEM observations demonstrate that vesicles and tube-like and branched tube structures coexist, indicating that the unique structure of CA has a significant influence on the phase transformations of the mixtures. At higher x value, x = 0.5, a dilute solution was obtained, with a lower viscosity comparable to water. However, at x from 0.25 to 0.5, the system exhibits characteristic worm-like micelles with shearing thinning behavior at low and high shear rates but a Newtonian fluid behavior at intermediate shear rate range. At x = 0.2, the sample separates into two phases. The upper phase also shows shear thinning behavior and a narrow plateau at intermediate shear rate. At x < 0.2, the system exhibits similar rheological behavior to the original TTAL vesicular solution. For comparison, an investigation of the cetyltrimethylammonium hydroxide (CTAOH)/LA/H(2)O system with long chain cationic surfactant is also reported. The results of these studies may provide a better understanding of biological membranes and the effects of biosurfactants on surfactant phase transitions. PMID:20225846

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

    PubMed

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

    2011-06-01

    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

  9. Characterizing the acid/base behavior of oil-soluble surfactants at the interface of nonpolar solvents with a polar phase.

    PubMed

    Lee, Joohyung; Zhou, Zhang-Lin; Behrens, Sven Holger

    2015-06-01

    We propose a simple method of characterizing the (Lewis) acid/base behavior of oil-soluble nonionic surfactants at the interface of nonpolar solvents with a polar phase. Using interfacial tensiometry, we probe the effective acidic and basic response of nonpolar surfactant solutions to contact with a variety of polar reference liquids. The measured interfacial tensions are used as experimental coefficients in a set of equations borrowed from the thermodynamic "surface energy component model" of van Oss, Chaudhury, and Good (vOCG), but used here in a more heuristic fashion and with a revised interpretation of the parameters extracted to describe the dispersive, acidic, and basic character of the sample. We test the proposed characterization method using alkane solutions of purified polyisobutylene succinimide (PIBS) surfactants with systematic structural variations, and observe that the inferred parameter values are consistent with, and sensitive to, subtle differences in the surfactant chemistry. This suggests the possibility to compare different surfactant solutions semiquantitatively with regard to their acidic and basic character. In a further illustration of the proposed analysis, we characterize a solution of commercial PIBS surfactant in hexane, and find that the parameters obtained by the proposed method correctly predict the solution interfacial tension with a polar liquid not included among the chosen reference liquids. PMID:25978798

  10. Diffusing wave spectroscopy study of the colloidal interactions occurring between casein micelles and emulsion droplets: comparison to hard-sphere behavior.

    PubMed

    Gaygadzhiev, Zafir; Corredig, Milena; Alexander, Marcela

    2008-04-15

    Understanding the underlying processes that govern interparticle interactions in colloidal systems is fundamental to predicting changes in their bulk properties. In this paper we discuss the colloidal behavior of casein micelles and protein-stabilized fat globules individually and in a mixture. The colloidal interactions were observed by transmission diffusing wave spectroscopy. The turbidity parameter, l*, and the diffusion coefficients of the samples studied were measured experimentally and compared to the theoretically calculated parameters for a hard-sphere system. The light scattering properties of casein micelles (volume fraction phi = 0.1-0.2) dispersed in milk permeate showed no deviation from the theoretically predicted model. Whey protein isolate (WPI)-stabilized emulsions (phi = 0.025-0.1) prepared either in milk permeate or in 5 mM imidazole buffer at pH 6.8 showed a behavior identical to that of the hard-sphere model. Similarly to the WPI-stabilized fat globules, the sodium caseinate (NaCas)-stabilized emulsions (phi = 0.025-0.1) prepared in milk permeate also showed resemblance to the theory. In contrast, NaCas-stabilized emulsions prepared in 5 mM imidazole buffer exhibited some discrepancy from the theoretically calculated parameters. The deviation from theory is attributed to the enhanced steric stabilization properties of these droplets in a low ionic strength environment. When recombined milks made from concentrated milk and WPI- and NaCas-stabilized droplets prepared in permeate (phi = 0.125-0.2) were studied, the experimental data showed a significant deviation from the theoretical behavior of a hard-sphere model due to mixing of two different species. PMID:18324850

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

    PubMed

    ElSayed, Eman M; Prasher, Shiv O

    2014-03-01

    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?

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

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Jin, Chao

    2011-01-01

    Zeolite ZSM-5 was synthesized for the first time in a nonionic emulsion composed of polyoxyethylated alkylphenol, butanol, cyclohexane and tetraethylammonium hydroxide (TEAOH)-containing zeolite synthesis mixture. The crystallization kinetics in the emulsion was investigated and the ZSM-5 product was characterized in detail by XRD, SEM, FT-IR, TG, N 2 adsorption and CHN analysis techniques. Compared with the conventionally hydrothermal synthesis with the same structure directing agent TEAOH, the emulsion system allows rapid crystallization of ZSM-5. The ZSM-5 product exhibits unusual agglomerated structure and possesses larger specific surface area. The FT-IR, TG results plus CHN analysis show the encapsulation of a trace of emulsion components in the emulsion ZSM-5. Control experiments show the emulsion system exerts the crystallization induction and morphological adjustment effects mainly during the aging period. The effects are tentatively attributed to the confined space domains, surfactant-water interaction as well as surfactant-growing crystals interaction existing in the emulsion.

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

    NASA Astrophysics Data System (ADS)

    Mobin, M.; Khan, M. A.

    2014-01-01

    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.

  14. Nanoscale double emulsions stabilized by single-component block copolypeptides.

    PubMed

    Hanson, Jarrod A; Chang, Connie B; Graves, Sara M; Li, Zhibo; Mason, Thomas G; Deming, Timothy J

    2008-09-01

    Water-in-oil-in-water emulsions are examples of double emulsions, in which dispersions of small water droplets within larger oil droplets are themselves dispersed in a continuous aqueous phase. Emulsions occur in many forms of processing and are used extensively by the foods, cosmetics and coatings industries. Because of their compartmentalized internal structure, double emulsions can provide advantages over simple oil-in-water emulsions for encapsulation, such as the ability to carry both polar and non-polar cargos, and improved control over release of therapeutic molecules. The preparation of double emulsions typically requires mixtures of surfactants for stability; the formation of double nanoemulsions, where both inner and outer droplets are under 100 nm, has not yet been achieved. Here we show that water-in-oil-in-water double emulsions can be prepared in a simple process and stabilized over many months using single-component, synthetic amphiphilic diblock copolypeptide surfactants. These surfactants even stabilize droplets subjected to extreme flow, leading to direct, mass production of robust double nanoemulsions that are amenable to nanostructured encapsulation applications in foods, cosmetics and drug delivery. PMID:18769436

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

    SciTech Connect

    Somasundaran, Prof. P.

    2001-02-27

    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.

  16. The adsorption behavior of ionic surfactants and their mixtures with nonionic polymers and with polyelectrolytes of opposite charge at the air-water interface.

    PubMed

    Bahramian, Alireza; Thomas, Robert K; Penfold, Jeffrey

    2014-03-13

    The surface phase approach of Butler has been used to derive a model of the surface tension (ST) of surfactant solutions in terms of the ST of the surfactant in the absence of water, an area parameter corresponding approximately to the limiting area per molecule, and the critical micelle concentration (CMC). This isotherm is then used to account for the ST behavior of aqueous solutions of weakly interacting polymer-surfactant (P-S) and strongly interacting polyelectrolyte-surfactant (PE-S) mixtures. For P-S systems, no additional parameters are required other than the critical aggregation concentration (CAC) and the onset of the ST plateau at micellization (T3). The model accounts for experimental isotherms for sodium dodecyl sulfate (SDS) with poly(ethylene oxide) or poly(vinylpyrrolidone). For PE-S systems, the initial CAC has no effect on the ST and is well below the decrease in ST that leads to the first ST plateau at T1. This decrease is modeled approximately using a Langmuir isotherm. The remaining ST behavior is analyzed with the model surfactant isotherm and includes modeling the ST when there is separation into two phases. The behavior in the phase separation region depends on the dissociability of the PE-S complex. Loss of surface activity accompanied by a peak in the ST may occur when there is part formation of a nondissociable complex (neutral with segment/surfactant = 1). The model successfully explains the ST of several experimental systems with and without ST peaks, including poly(dimethyldiallylammonium chloride)-SDS and poly(sodium styrenesulfonate)-alkyltrimethylammonium bromide (C(n)TAB) with n = 12, 14, and 16. PMID:24552283

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

    PubMed

    Fan, Yanru; Simon, Sébastien; Sjöblom, Johan

    2010-07-01

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

  18. Critical behavior of a cationic-surfactant-water-salt system near and far from the Krafft temperature

    NASA Astrophysics Data System (ADS)

    Martín, Ana; Ortega, Francisco; Rubio, Ramón G.

    1995-08-01

    The cationic micellar system docecylammonium chloride +water+KCl has been studied by light scattering near the critical point for different concentrations of salt. For the lowest value of salt concentration, the critical point is rather close to the Krafft line, and therefore there is a critical mixture in equilibrium with two noncritical phases: vapor and pure solid surfactant. Both the correlation length and osmotic susceptibility data for the critical mixtures can be accurately described by the usual three-dimensional Ising exponents for all values of the concentration of KCl (cKCl). This is in agreement with theoretical predictions that indicate that approaching a critical end point does not affect the critical exponents. Two off-critical mixtures have also been studied, and their behavior has been found to be compatible with the linear model equation of state.

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

    PubMed

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

    2010-04-20

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

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

    SciTech Connect

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

    1991-07-01

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

  1. Nanoscale and Microscale Iron Emulsions for Treating DNAPL

    NASA Technical Reports Server (NTRS)

    Geiger, Cherie L.

    2002-01-01

    This study demonstrated the feasibility of using emulsified nanoscale and microscale iron particles to enhance dehalogenation of (Dense Non-Aqueous Phase Liquid) DNAPL free-phase. The emulsified system consisted of a surfactant-stabilized, biodegradable oil-in-water emulsion with nanoscale or microscale iron particles contained within the emulsion droplets. It was demonstrated that DNAPLs, such as trichloroethene (TCE), diffuse through the oil membrane of the emulsion particle whereupon they reach an aqueous interior and the surface of an iron particle where dehalogenation takes place. The hydrocarbon reaction by-products of the dehalogenation reaction, primarily ethene (no chlorinated products detected), diffuse out of the emulsion droplet. This study also demonstrated that an iron-emulsion system could be delivered in-situ to the DNAPL pool in a soil matrix by using a simulated push well technique. Iron emulsions degraded pure TCE at a rate comparable to the degradation of dissolved phase TCE by iron particles, while pure iron had a very low degradation rate for free-phase TCE. The iron-emulsion systems can be injected into a sand matrix where they become immobilized and are not moved by flowing water. It has been documented that surfactant micelles possess the ability to pull pooled TCE into emulsion droplets where degradation of TCE takes place.

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

    Microsoft Academic Search

    K. I. Segall; H. D. Goff

    1999-01-01

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

  3. Aggregation in a high internal phase emulsion observed by SANS and USANS

    NASA Astrophysics Data System (ADS)

    Zank, J.; Reynolds, P. A.; Jackson, A. J.; Baranyai, K. J.; Perriman, A. W.; Barker, J. G.; Kim, M.-H.; White, J. W.

    2006-11-01

    As part of a wider study into high internal phase emulsions, we have prepared and studied by SANS and USANS the structure of an unstable emulsion consisting of 90% by volume saturated ammonium nitrate dispersed as micron-scale droplets in hexadecane, stabilised by the surfactant Pluronic L92. Similar emulsions produced using polyisobutylene-based surfactants, reported earlier, are highly stabilised by a significant number of surfactant rich reverse micelles a few nanometres in diameter in the oil phase. The aqueous-oil droplet interfaces are coated with a monolayer of surfactant, while a very small amount of surfactant is aggregated into micron-scale surfactant-rich objects. In contrast, the Pluronic emulsion contains an insignificant number of reverse micelles and a complex multilayered interface between oil and aqueous phases. Now, the great majority of added surfactant is in the form of micron scale, fractally linked, blocks of lamellar phase at the aqueous-oil droplet interfaces. The lamellar phase can be characterised by the Bragg peaks observed in three different isotopic contrasts by SANS. We attribute the shear instability of the Pluronic emulsion to the more hydrophilic nature of the surfactant which causes both depletion of reverse micelles in the oil phase, and aggregation into the blocks of lamellar phase.

  4. Pickering interfacial catalysis for biphasic systems: from emulsion design to green reactions.

    PubMed

    Pera-Titus, Marc; Leclercq, Loïc; Clacens, Jean-Marc; De Campo, Floryan; Nardello-Rataj, Véronique

    2015-02-01

    Pickering emulsions are surfactant-free dispersions of two immiscible fluids that are kinetically stabilized by colloidal particles. For ecological reasons, these systems have undergone a resurgence of interest to mitigate the use of synthetic surfactants and solvents. Moreover, the use of colloidal particles as stabilizers provides emulsions with original properties compared to surfactant-stabilized emulsions, microemulsions, and micellar systems. Despite these specific advantages, the application of Pickering emulsions to catalysis has been rarely explored. This Minireview describes very recent examples of hybrid and composite amphiphilic materials for the design of interfacial catalysts in Pickering emulsions with special emphasis on their assets and challenges for industrially relevant biphasic reactions in fine chemistry, biofuel upgrading, and depollution. PMID:25644631

  5. Antagonistic mixing behavior of cationic gemini surfactants and triblock polymers in mixed micelles.

    PubMed

    Bakshi, Mandeep Singh; Singh, Jasmeet; Kaur, Gurinder

    2005-05-01

    Conductance (kappa), pyrene fluorescence (I1/I3), cloud point (C(P)), and Krafft temperature (K(T)) measurements have been carried out for various dimethylene bis(alkyldimethylammonium bromide) (gemini) surfactants with different poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock polymers (TBP). From the kappa and I1/I3 studies, the critical micelle concentrations of mixed micelle formation between the gemini and TBP have been determined using regular solution theory. It has been observed that mixed micelle formation in all the binary mixtures of gemini+TBP occurs due to the unfavorable mixing, the magnitude of which decreases with increased hydrophobicity of the gemini component. The results are further supported by evaluating the mean micelle aggregation number and enthalpy of fusion from fluorescence and Krafft temperature measurements, respectively. PMID:15797439

  6. Perfluoro-alcohol-induced complex coacervates of polyelectrolyte-surfactant mixtures: phase behavior and analysis.

    PubMed

    Nejati, Mahboubeh M; Khaledi, Morteza G

    2015-05-26

    Perfluorinated alcohols and acids such as hexafluoroisopropanol (HFIP), trifluoroethanol, trifluoroacetic acid, pentafluoropropionic acid, and heptafluorobutyric acid induce coacervation and phase separation in aqueous solutions of a wide variety of individual and mixed amphiphiles [ Khaledi Langmuir 2013 , 29 , 2458 ]. This paper focuses on HFIP-induced complex coacervate formation in the mixtures of anionic polyelectrolytes, such as sodium salt of poly(methacrylic acid) (PMA) or poly(acrylic acid) (PAA) and cationic surfactants of alkyltrimethylammonium bromides. In purely aqueous media and over a wide concentration range, mixtures of PMA and CTAB form the catanionic complex (CTA(+)PM(-)) that is insoluble in water (white precipitate). Upon addition of a small percentage of HFIP, the mixture goes through phase transition and formation of two distinctly clear liquid phases. The phase diagram for the HFIP-PMA-CTAB coacervate system was studied. The coacervate volume was determined as a function of system variables such as charge ratio as well as total and individual concentrations of the system components. These results, combined with the chemical composition analysis of the separated aqueous top-phase and coacervate bottom-phase, shed light on the coacervation mechanism. The results suggest that exchange of counterions and ion-pair formation play critical roles in the coacervation process. This process facilitated by HFIP through solvation of the head groups and dehydration of the hydrophobic moieties of the catanionic complex. Because of the presence of HFIP, coacervation occurs over a wide range of concentrations and charge ratios of the oppositely charged polyelectrolyte and surfactant. PMID:25920513

  7. Theoretical Prediction and experimental measurement of the mixed flocculation/coalescence rate of ionic Hexadecane-in-water nano-emulsions

    E-print Network

    German Urbina-Villalba; Neyda Garcia-Valera; Kareem Rahn-Chique

    2015-07-07

    Theoretical calculations of the mixed aggregation/coalescence (kFC) rate corresponding to a set of hexadecane-in-water nano-emulsions stabilized with sodium dodecyl sulphate (SDS) at different NaCl concentrations are presented. The rates were obtained through the change of the total number of aggregates of the dispersions as a function of time, predicted by Emulsion Stability Simulation (ESS). Two different models were implemented in order to mimic the dependence of the surface excess of the surfactant on the salt concentration. Experimental measurements of kFC were also made, based on the change of the turbidity of the emulsions as a function of time. A satisfactory agreement between theory and experiment is only attained if the model of surfactant adsorption accounts for the balance between the salting out of the surfactant solution and the partial screening of the surface charge of the drops induced by the increase of the ionic strength of the continuous phase. The observed behavior cannot be justified on the grounds of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Instead, the reversible flocculation of the aggregates of any size is proposed as an alternative mechanism to explain the dependence of kFC as a function of the salt concentration.

  8. Antioxidant activity of alkyl gallates and glycosyl alkyl gallates in fish oil in water emulsions: Relevance of their surface active properties and of the type of emulsifier.

    PubMed

    González, María J; Medina, Isabel; Maldonado, Olivia S; Lucas, Ricardo; Morales, Juan C

    2015-09-15

    The antioxidant activity of gallic acid and a series of alkyl gallates (C4-C18) and glycosylated alkyl gallates (C4-C18) on fish oil-in-water emulsions was studied. Three types of emulsifiers, lecithin, Tween-20 and sodium dodecyl sulphate (SDS) were tested. A nonlinear behavior of the antioxidant activity of alkyl gallates when increasing alkyl chain length was observed for emulsions prepared with lecithin. Medium-size alkyl gallates (C6-C12) were the best antioxidants. In contrast, for emulsions prepared with Tween-20, the antioxidants seem to follow the polar paradox. Glucosyl alkyl gallates were shown previously to be better surfactants than alkyl gallates. Nevertheless, they exhibited a worse antioxidant capacity than their corresponding alkyl gallates, in emulsions prepared with lecithin or Tween-20, indicating the greater relevance of having three OH groups at the polar head in comparison with having improved surfactant properties but just a di-ortho phenolic structure in the antioxidant. PMID:25863628

  9. The effects of whey proteins and homogenization pressure on the stability of concentrated soft drink emulsions

    E-print Network

    Wong, Tsui-Yin

    2002-01-01

    effect of the polysaccharide. Ibanoglu (2002) also mentioned that gum arabic could be a stability enhancer of emulsions because it had a lower surface activity than proteins and surfactants. In contrast, emulsions prepared using sweet whey or gum... of surfactant, or polysaccharide, and on environmental conditions such as temperature or pressures of homogenization. The mineral content of sweet WPC was less than that of acid WPC (Table III). The higher mineral content might have enhanced the electrostatic...

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

    PubMed

    Fuchs, Ido; Avnir, David

    2013-03-01

    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

  11. Precipitation and Micellar Properties of Novel Mixed Anionic Extended Surfactants and a Cationic Surfactant

    Microsoft Academic Search

    Donyaporn Panswad; David A. Sabatini; Sutha Khaodhiar

    Surfactant-modified mineral surfaces can provide both a hydrophobic coating for adsorbing organic contaminants and, in the\\u000a case of ionic surfactants, a charged exterior for adsorbing oppositely charged species. This research evaluates the precipitation\\u000a phase boundaries and synergistic behavior of the mixtures of carboxylate-based anionic extended surfactants with a pyridinium-based\\u000a cationic surfactant. One cationic surfactant (cetylpyridinium chloride) and four anionic extended

  12. Microencapsulation using an oil-in-water-in-air 'dry water emulsion'.

    PubMed

    Carter, Benjamin O; Weaver, Jonathan V M; Wang, Weixing; Spiller, David G; Adams, Dave J; Cooper, Andrew I

    2011-08-01

    We describe the first example of a tri-phasic oil-in-water-in-air 'dry water emulsion'. The method combines highly stable oil-in-water emulsions prepared using branched copolymer surfactants, with aqueous droplet encapsulation using 'dry water' technology. PMID:21709910

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

    SciTech Connect

    Prof. P. Somasundaran

    2002-09-30

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

  14. Relation between viscosity and stability for heavy oil emulsions 

    E-print Network

    Ye, Sherry Qianwen

    1998-01-01

    series 49 TABLE Page 4. 2 Bingham Plastic model parameters for oil volume fraction series . . . . . . 54 4. 3 $' at different shear rates . 61 LIST OF FIGURES FIGURE Page Flocculation and coalescence states in emulsions . . . . . 1. 2 Schematic... efforts have been made to improve surfactants (emulsifiers) and/or process conditions in order to enhance or control stability. The stability is generally determined by real-time measurement of phase separation. Depending on the type of the surfactant...

  15. Behavior of asphaltene model compounds at w/o interfaces.

    PubMed

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

    2010-02-16

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

  16. Separation of Organic Compounds from Surfactant Solutions: A Review

    Microsoft Academic Search

    Hefa Cheng; David A. Sabatini

    2007-01-01

    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

  17. A novel method for preparing oil-in-water-in-oil type multiple emulsions using organophilic montmorillonite clay mineral

    Microsoft Academic Search

    Tomoko Sekine; Katsunori Yoshida; Fumiaki Matsuzaki; Toshio Yanaki; Michihiro Yamaguchi

    1999-01-01

    A stable formula using oil-in-water-in-oil (O\\/W\\/O) type multiple emulsions was investigated. The components consisted of hydrophilic\\u000a nonionic surfactant (HCO-60), organophilic montmorillonite, and lipophilic nonionic surfactant (DIS-14). O\\/W\\/O emulsions were\\u000a prepared by a double-step procedure in which an O\\/W emulsion was prepared in the first step, and then the O\\/W emulsion was\\u000a “re-emulsified” in an oil phase with organophilic montmorillonite. The

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

    SciTech Connect

    Prof. P. Somasundaran

    2003-03-31

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

  19. Cleavable surfactants

    Microsoft Academic Search

    Per-Erik Hellberg; Karin Bergström; Krister Holmberg

    2000-01-01

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

  20. Insights into the Partitioning Behavior of Secondary Surfactants in a Microemulsion-Based Synthesis of Metal Nanoparticles: A DLS and 2D NMR Spectroscopic Investigation.

    PubMed

    Dumas, Christophe; Meledandri, Carla J

    2015-07-01

    Diffusion-ordered NMR spectroscopy (DOSY) and nuclear Overhauser effect spectroscopy (NOESY) have been used to explore the diffusion and partitioning behavior of secondary surfactants added to suspensions of reverse micelles (RMs) containing either silver or gold nanoparticles (NPs), with an aim of advancing our understanding of the mechanism of metal NP extraction and/or surface functionalization with specific capping agents as performed during a microemulsion-based synthesis. We have coupled these NMR techniques with corresponding dynamic light scattering (DLS) measurements of RMs, with and without encapsulated metal NPs, upon addition of secondary surfactants. Using oleylamine (OAm), oleic acid (OA), dodecylamine (DDAm), and dodecanethiol (DDT), we show that all four secondary surfactants can rapidly diffuse into/out of the RM environment with their head groups in close proximity to the RM interior and encapsulated water molecules; however, surfactant molecules containing a terminal -NH2 or -COOH group undergo a persistent association with the molecules of the RMs, thus solubilizing and partially sequestering a portion of the total concentration of these secondary agents within the RM interface for a lengthened period of time (in relation to the time frame of the DOSY experiments) and slowing their rate of exchange with freely diffusing molecules in the bulk solvent. The extraction of Ag or Au NPs from RMs into organic phase was determined to be critically dependent on the type and concentration of secondary surfactant added to the system, with DDT proving to be most efficient for the extraction of Ag NPs, while OA was shown to be most efficient for Au NPs. Consideration of the results obtained from this particular combination of techniques has provided new knowledge with respect to dynamic metal NP-containing microemulsion systems. PMID:26073418

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

    Microsoft Academic Search

    Ron S. Faibish; Yoram Cohen

    2001-01-01

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

  2. Polypyrrole–montmorillonite nanocomposites synthesized by emulsion polymerization

    Microsoft Academic Search

    S. H. Hong; B. H. Kim; J. Joo; J. W. Kim; Hyung J. Choi

    2001-01-01

    The structural, electrical, magnetic, and thermal properties were investigated for the nanocomposites of polypyrrole (PPy) and inorganic clay (Na+-montmorillonite) prepared by emulsion polymerization. Dodecylbenzenesulfonic acid (DBSA) was used as emulsifier (surfactant) and dopant. The X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images showed that the conducting PPy was intercalated into the clay layers in nanoscale (<10 Å). The

  3. Recent advances in the combustion of water fuel emulsion

    Microsoft Academic Search

    T. Kadota; H. Yamasaki

    2002-01-01

    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

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

    Microsoft Academic Search

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

    2007-01-01

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

  5. Fine-tuning the nonequilibrium behavior of oppositely charged macromolecule/surfactant mixtures via the addition of nonionic amphiphiles.

    PubMed

    Fegyver, Edit; Mészáros, Róbert

    2014-12-23

    The various commercial applications of oppositely charged polyelectrolytes (P) and ionic surfactants (S) with added nonionic amphiphiles initiated intensive research on the polyion/mixed surfactant interaction. A large group of earlier studies revealed that one of the major effects of the nonionic cosurfactants is the suppression of the associative phase separation of P/S systems. In contrast, recent studies indicated that in the dilute surfactant concentration range the added uncharged amphiphile enhances the precipitation concentration range. In order to rationalize these observations, the mixtures of poly(diallyldimethylammonium chloride) (PDADMAC), sodium dodecyl sulfate (SDS), and dodecyl maltoside (C12G2) are investigated using a variety of experimental methods. It is shown that the nonionic cosurfactant has two distinct and competing impacts on the mixed surfactant binding onto the polyions. The composition dependent variation of the chemical potentials of the amphiphiles determines which of these effects is the dominant one, explaining the seemingly diverse earlier observations and their interpretations. We also demonstrate that the nonionic amphiphile affects considerably the nonequilibrium features of polyion/ionic surfactant complexation. Namely, the presence of the uncharged surfactant can destabilize the colloidal dispersion of P/S nanoparticles formed in the two-phase composition range. However, at the same concentration range highly stable dispersions of polyion/mixed surfactant nanoparticles can be produced through the application of a new two-step solution preparation technique. This method is based on the order of addition effect of the two surfactants which can be utilized in future scientific and industrial applications. PMID:25469711

  6. Etching of surfactant from solution-processed, type-separated carbon nanotubes and impact on device behavior.

    PubMed

    Kane, Alexander A; Ford, Alexandra C; Nissen, April; Krafcik, Karen L; Léonard, François

    2014-03-25

    Semiconducting single-walled carbon nanotubes (SWCNTs) have great potential for use in electronic and optoelectronic devices. However, methods for synthesizing SWCNTs produce a mixture of metallic and semiconducting materials, which require additional processing to separate by electronic type. Purification and enrichment of the semiconducting fraction is readily achieved by using the centrifugation of aqueous suspensions of SWCNTs with the help of surfactants, but this leaves residual surfactant on the SWCNT surface that can impact their electronic and optical properties. Here, we present a detailed study of the sodium taurodeoxycholate (STDC) surfactant removal process during vacuum annealing, showing that it occurs through fragmentation of the surfactant, and that complete removal requires exceedingly high temperatures, which indicates strong binding to the SWCNTs. We then present an approach based on air oxidation and mild annealing to completely remove the surfactant while maintaining the SWCNT properties. Using this approach, we compare single SWCNT electronic devices with and without STDC and show that, despite the very strong surfactant binding, it does not affect device performance substantially. PMID:24512110

  7. Micelle formation and CMC of gemini surfactants: a thermodynamic model

    Microsoft Academic Search

    Terri A. Camesano; R. Nagarajan

    2000-01-01

    Gemini surfactants possess a structure resembling a pair of conventional single chain surfactants covalently connected by a spacer. The spacer can vary in length and chemical structure. In this paper, the aggregation behavior of gemini surfactants is examined on the basis of a free energy model developed by extending our theory for conventional surfactants. Free energy contributions beyond those considered

  8. Enhanced oil recovery method using surfactant compositions for improved oil mobility

    SciTech Connect

    Current, S.P.

    1992-05-05

    This patent describes a surfactant composition useful for coacting with an emulsion in a petroleum reservoir which includes at least two surfactant components, one of the components being an anionic surfactant and the other of the components being a nonionic polyether surfactant which is selected from among polyol ethers, polyol esters and phenolic resins, wherein the anionic surfactant comprises an alpha olefin sulfonate dimmer having from 15 to 45 carbon atoms, wherein the ratio of the components is selected to reduce the viscosity of an emulsion in a petroleum reservoir to near, or less than, the viscosity of the oil phase alone and wherein the anionic surfactant component is from 30 to 70 weight percent of the total surfactant composition.

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    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.

  10. Gemini surfactants

    Microsoft Academic Search

    Milton J. Rosen; David J. Tracy

    1998-01-01

    The literature, including patents, describing the emerging area of gemini surfactants is reviewed. The differences in structure\\/property\\u000a relationships between gemini and comparable conventional surfactants are described and discussed in terms of their predicted\\u000a performance properties. Supportive performance data are enumerated.

  11. TbxBi1-xFeO3 nanoparticulate multiferroics fabricated by micro-emulsion technique: Structural elucidation and magnetic behavior evaluation

    NASA Astrophysics Data System (ADS)

    Anwar, Zobia; Azhar Khan, Muhammad; Mahmood, Azhar; Asghar, M.; Shakir, Imran; Shahid, Muhammad; Bibi, Ismat; Farooq Warsi, Muhammad

    2014-04-01

    Tb-doped BiFeO3 multiferroics nanoparticles fabricated via micro-emulsion route were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The fully characterized TbxBi1-xFeO3 nanoparticles were then subjected to magnetic behavior evaluation for various technological applications. The thermogravimetric analysis (TGA) conducted in the range 25-1000 °C predicted the temperature (~960 °C) for phase formation. XRD estimated the crystallite size 30-47 nm, while the particles size estimated by SEM was found (80-120 nm). The XRD data confirmed the rhombohedral (space group R3c) phase with average cell volume 182.66 Å3 (for BiFeO3). Various other physical parameters like bulk density, X-ray density and porosity were also determined from the XRD data and found in agreement with theoretical predictions. The magnetic studies showed that as Bi3+ was substituted by Tb3+, all magnetic parameters were altered. The maximum saturation magnetization (Ms) (0.6691 emug-1) was exhibited by Tb0.02Bi0.98FeO3 while the Tb0.00Bi1.00Fe1.00O3 showed the maximum (549 Oe) coercivity. The evaluated magnetic behavior categorized these materials as soft magnetic materials that may be useful for fabricating advanced technological applications.

  12. Emulsion gel beads of calcium pectinate capable of floating on the gastric fluid: effect of some additives, hardening agent or coating on release behavior of metronidazole

    Microsoft Academic Search

    Pornsak Sriamornsak; Nartaya Thirawong; Satit Puttipipatkhachorn

    2005-01-01

    Emulsion gel (EMG) beads of calcium pectinate capable of floating in the gastric condition were developed using an emulsion-gelation method and their release properties were investigated. Attempts to modify the drug release were made by applying some additives into the starting solution prior to bead formation, by hardening with glutaraldehyde, and by coating with polymer. The metronidazole-loaded EMG beads were

  13. Polymer/surfactant transport in micellar flooding

    SciTech Connect

    Chiou, C.S.; Kellerhals, G.E.

    1981-10-01

    For the surfactant formulations used (particular surfactant concentration, surfactant type, cosolvent type, cosolvent concentration, etc.), the results show that surfactant systems containing polymer as a mobility control agent may exhibit adverse polymer transport behavior during flow through porous media. Polymer generally lagged behind the surfactant even though the two species were injected simultaneously in the surfactant slug. This poor polymer transport definitely could have a detrimental effect on the efficiency of a micellar flooding process in the field. Phase studies show that when some surfactant systems containing xanthan gum are mixed with crude oil at various salinities, a polymer-rich, gel-like phase forms. The polymer lag phenomenon in core tests can be related to phase separation due to divalent cations generated in situ as a result of ion exchange with the clays and the surfactant. 18 refs.

  14. Flow of Super-Concentrated Emulsions

    NASA Astrophysics Data System (ADS)

    Masalova, Irina; Malkin, Alexander Ya.

    2006-05-01

    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.

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

    SciTech Connect

    Wasan, D.T.

    1990-08-01

    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.

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

    Microsoft Academic Search

    A. Pinotti; A. Bevilacqua; N. Zaritzky

    1997-01-01

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

  17. Dehydration of oil waste emulsions by means of flocculants

    SciTech Connect

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

    1995-05-01

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

  18. Rheological properties of model alkali-soluble associative (HASE) polymer in ionic and non-ionic surfactant solutions

    Microsoft Academic Search

    W. P. Seng; K. C. Tam; R. D. Jenkins

    1999-01-01

    The rheological properties of 0.5 wt.% aqueous solution of hydrophobically alkali-soluble emulsions (HASE) at around pH 9 in the presence of cationic, anionic and non-ionic surfactants were examined. The results revealed that the presence of surfactant below a critical concentration c* (around cmc of surfactant) strengthened the associating network through the formation of mixed polymer hydrophobic group\\/surfactant aggregates. The increased

  19. Ultrasonication-assisted preparation and characterization of emulsions and emulsion gels for topical drug delivery.

    PubMed

    Singh, Vinay K; Behera, Baikuntha; Pramanik, Krishna; Pal, Kunal

    2015-03-01

    The current study describes the use of ultrasonication for the preparation of biphasic emulsions and emulsion gels for topical drug delivery. Sorbitan monostearate (SMS) was used as the surfactant for stabilizing the interface of sesame oil (apolar phase) and water (polar phase). Emulsions were formed at lower concentrations of SMS, whereas emulsion gels were formed at higher concentrations of SMS. The formulations were characterized by fluorescent microscopy, X-ray diffraction, viscosity, stress relaxation, spreadability, and differential scanning calorimetry studies. Fluorescence microscopy suggested formation of oil-in-water type of formulations. There was an increase in the viscosity, bulk resistance, and firmness of the formulations as the proportions of SMS was increased. The emulsion gels were viscoelastic in nature. Thermal studies suggested higher thermodynamic stability at higher proportions of either SMS or water. Metronidazole, a model antimicrobial drug, was incorporated within the formulations. The release of the drug from the formulations was found to be diffusion mediated. The drug-loaded formulations showed sufficient antimicrobial efficiency to be used as carriers for topical antimicrobial drug delivery. PMID:25470664

  20. Effect of cationic surfactants on characteristics and colorimetric behavior of polydiacetylene/silica nanocomposite as time-temperature indicator

    NASA Astrophysics Data System (ADS)

    Nopwinyuwong, Atchareeya; Kitaoka, Takuya; Boonsupthip, Waraporn; Pechyen, Chiravoot; Suppakul, Panuwat

    2014-09-01

    Polydiacetylene (PDA)/silica nanocomposites were synthesized by self-assembly method using polymerizable amphiphilic diacetylene monomers, 10,12-pentacosadiynoic acid (PCDA). Addition of cationic surfactants (PDADMAC and CTAB) to PDA/SiO2 nanocomposites induced higher intermolecular force which affected their size, shape and color transition. Pure PDA, PDA/SiO2, PDA/SiO2/PDADMAC and PDA/SiO2/CTAB were investigated by particle size analysis, TEM, SEM, UV-vis spectroscopy and FT-IR. It was found that the PDA/SiO2 nanocomposites exhibited slightly larger particle sizes than those of other samples. The PDA/SiO2 nanocomposites with a core-shell structure were almost regarded as spherical-shaped particles. Cationic surfactants, especially CTAB, presumably affected the particle size and shape of PDA/SiO2 nanocomposites due to the disruption of hydrogen bonding between PDA head group and ammonium group. The colorimetric response of both PDA/SiO2/surfactant and surfactant-free PDA/SiO2 aqueous solutions directly changed in relation to time and temperature; thus they were expected to be applied as a new polymer-based time-temperature indicator (TTI).

  1. A dually effective inorganic salt at inducing obvious viscoelastic behavior of both cationic and anionic surfactant solutions.

    PubMed

    Lu, Ting; Xia, Lian'gen; Wang, Xiaodong; Wang, Aiqing; Zhang, Tao

    2011-08-16

    Hydrazine nitrate (HN), an inorganic salt, was first found to have dual effects on inducing obvious viscoelasticity of both cationic and anionic surfactant solutions. It was interesting that the surfactant solutions exhibited characteristic wormlike micelle features with strong viscoelastic properties upon the addition of this inorganic salt. The rheological properties of the surfactant solutions have been measured and discussed. The apparent viscosity of the solutions showed a volcano change with an increase of the HN concentration. Correspondingly, the microstructures of the micelles in the solutions changed with the apparent viscosity. First, wormlike micelles began to form and grew with an increase of the HN concentration. Subsequently, the systems exhibited linear viscoelasticity with characteristics of a Maxwell fluid in the intermediate mass fraction range, which originated from a 3D entangled network of wormlike micelles. Finally, a transition from linear micelles to branched ones probably took place at higher HN contents. In addition, the origin of the dual effects brought by HN addition on inducing viscoelasticity in both cationic and anionic surfactant solutions was investigated. PMID:21721509

  2. Modified montmorillonite clay microparticles for stable oil-in-seawater emulsions.

    PubMed

    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

    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

  3. Effect of polymer-surfactant association on colloidal force

    NASA Astrophysics Data System (ADS)

    Philip, John; Jaykumar, T.; Kalyanasundaram, P.; Raj, Baldev; Mondain-Monval, O.

    2002-07-01

    We investigate the forces between emulsion droplets in the presence of neutral polymer-surfactant complexes. The polymer used in our experiment was statistical copolymer of polyvinyl alcohol. The anionic surfactant used is sodiumdodecyl sulphate, the cationic surfactants are cetyltrimethylammonium bromide and tetradecyltrimethylammonium bromide, and the nonionic surfactant is nonylphenol ethoxylate (NP10). It has been found that the force profiles in the presence of surfactant-polymer complexes follow an exponential scaling with a characteristic decay length, close to the radius of gyration of the polymer alone. A continuous increase in the onset of repulsion is observed in the case of all three ionic surfactants, whereas no such variation was noticed in the case of nonionic surfactant, NP10. The experimental observations suggest that in the presence of charged surfactant molecules or micelles, the neutral polymer chain at the interface is converted into partial polyelectrolytes, where the charges on the chain repel each other and the electrostatic repulsion collectively leads to chain stretching. These results suggest that the associative polymers can be potential candidates for making the emulsions stable for a sufficiently long period.

  4. Oil emulsions of fluorosilicone fluids

    SciTech Connect

    Keil, J. W.

    1985-08-27

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

  5. Metal Separations Using Emulsion Liquid Membranes

    Microsoft Academic Search

    Reed M. Izatt; David V. Dearden; Don. W. McBride Jr; John L. Oscarson; John D. Lamb; James J. Christensen

    1983-01-01

    Emulsion membrane systems consisting of an aqueous metal salt source phase, a toluene membrane containing the macrocyclic ligand dicyclohexano-18-crown-6 (DC18C6) (0.02 M) and the surfactant sorbitan monooleate (3% v\\/v), and an aqueous 0.05 M Li4P2O7 receiving phase were studied with respect to the disappearance of metal from the source phase as a function of time. The salts Pb(NO3)2, Sr(NO3)2, TINO3,

  6. Demulsification of bitumen emulsions

    SciTech Connect

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

    1983-09-20

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

  7. Demulsification of bitumen emulsions

    SciTech Connect

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

    1982-03-23

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

  8. BEHAVIOR OF SURFACTANT MIXTURE AT SOLID/LIQUID AND OIL/LIQUID INTERFACE IN CHEMICAL FLOODING SYSTEMS

    SciTech Connect

    Prof. P. Somasundaran

    2002-03-01

    The aim of the project is to develop and evaluate efficient novel surfactant mixtures for enhanced oil recovery. Preliminary ultra-filtration tests suggest that two kinds of micelles may exist in binary surfactant mixtures at different concentrations. Due to the important role played in interfacial processes by micelles as determined by their structures, focus of the current work is on the delineation of the relationship between such aggregate structures and chemical compositions of the surfactants. A novel analytical centrifuge application is explored to generate information on structures of different surfactants aggregates. In this report, optical systems, typical output of the analytical ultracentrifuge results and four basic experiments are discussed. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. The partial specific volume was calculated to be 0.920. Four softwares: Optima{trademark} XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity experimental data. The sedimentation coefficient and aggregation number of NP-10 micelles obtained using the first three softwares at 25 C are 209, 127, and 111, respectively. The last one is closest to the result from Light Scattering. The reason for the differences in numbers obtained using the three softwares is discussed. Based on these tests, Svedberg and SEDFIT analysis are chosen for further studies. This approach using the analytical ultracentrifugation offers an unprecedented opportunity now to obtain important information on mixed micelles and their role in interfacial processes.

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

    Microsoft Academic Search

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

    2001-01-01

    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

  10. Dynamically reconfigurable complex emulsions via tunable interfacial tensions

    PubMed Central

    Zarzar, Lauren D.; Sresht, Vishnu; Sletten, Ellen M.; Kalow, Julia A.; Blankschtein, Daniel; Swager, Timothy M.

    2015-01-01

    Emulsification is a powerful, well-known technique for mixing and dispersing immiscible components within a continuous liquid phase. Consequently, emulsions are central components of medicine, food and performance materials. Complex emulsions, including multiple emulsions and Janus droplets which contain hemispheres of differing material, are of increasing importance1 in pharmaceuticals and medical diagnostics2, in the fabrication of microparticles and capsules3–5 for food6, in chemical separations7, in cosmetics8, and in dynamic optics9. Because complex emulsion properties and functions are related to the droplet geometry and composition, the development of rapid, simple fabrication approaches allowing precise control over the droplets’ physical and chemical characteristics is critical. Significant advances in the fabrication of complex emulsions have been made using a number of procedures, ranging from large-scale, less precise techniques that give compositional heterogeneity using high-shear mixers and membranes10, to small-volume but more precise microfluidic methods11,12. However, such approaches have yet to create droplet morphologies that can be controllably altered after emulsification. Reconfigurable complex liquids potentially have greatly increased utility as dynamically tunable materials. Here we describe an approach to the one-step fabrication of three- and four-phase complex emulsions with highly controllable and reconfigurable morphologies. The fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone and fluorocarbon liquids, and is applied to both the microfluidic and the scalable batch production of complex droplets. We demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by varying the interfacial tensions using hydrocarbon and fluorinated surfactants including stimuli-responsive and cleavable surfactants. This yields a generalizable strategy for the fabrication of multiphase emulsions with controllably reconfigurable morphologies and the potential to create a wide range of responsive materials. PMID:25719669

  11. Dynamically reconfigurable complex emulsions via tunable interfacial tensions

    NASA Astrophysics Data System (ADS)

    Zarzar, Lauren D.; Sresht, Vishnu; Sletten, Ellen M.; Kalow, Julia A.; Blankschtein, Daniel; Swager, Timothy M.

    2015-02-01

    Emulsification is a powerful, well-known technique for mixing and dispersing immiscible components within a continuous liquid phase. Consequently, emulsions are central components of medicine, food and performance materials. Complex emulsions, including Janus droplets (that is, droplets with faces of differing chemistries) and multiple emulsions, are of increasing importance in pharmaceuticals and medical diagnostics, in the fabrication of microparticles and capsules for food, in chemical separations, in cosmetics, and in dynamic optics. Because complex emulsion properties and functions are related to the droplet geometry and composition, the development of rapid, simple fabrication approaches allowing precise control over the droplets' physical and chemical characteristics is critical. Significant advances in the fabrication of complex emulsions have been made using a number of procedures, ranging from large-scale, less precise techniques that give compositional heterogeneity using high-shear mixers and membranes, to small-volume but more precise microfluidic methods. However, such approaches have yet to create droplet morphologies that can be controllably altered after emulsification. Reconfigurable complex liquids potentially have great utility as dynamically tunable materials. Here we describe an approach to the one-step fabrication of three- and four-phase complex emulsions with highly controllable and reconfigurable morphologies. The fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone and fluorocarbon liquids, and is applied to both the microfluidic and the scalable batch production of complex droplets. We demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by varying the interfacial tensions using hydrocarbon and fluorinated surfactants including stimuli-responsive and cleavable surfactants. This yields a generalizable strategy for the fabrication of multiphase emulsions with controllably reconfigurable morphologies and the potential to create a wide range of responsive materials.

  12. Synthesis of nanocrystalline CeO{sub 2} particles by different emulsion methods

    SciTech Connect

    Supakanapitak, Sunisa; Boonamnuayvitaya, Virote; Jarudilokkul, Somnuk, E-mail: somnuk.jar@kmutt.ac.th

    2012-05-15

    Cerium oxide nanoparticles were synthesized using three different methods of emulsion: (1) reversed micelle (RM); (2) emulsion liquid membrane (ELM); and (3) colloidal emulsion aphrons (CEAs). Ammonium cerium nitrate and polyoxyethylene-4-lauryl ether (PE4LE) were used as cerium and surfactant sources in this study. The powder was calcined at 500 Degree-Sign C to obtain CeO{sub 2}. The effect of the preparation procedure on the particle size, surface area, and the morphology of the prepared powders were investigated. The obtained powders are highly crystalline, and nearly spherical in shape. The average particle size and the specific surface area of the powders from the three methods were in the range of 4-10 nm and 5.32-145.73 m{sup 2}/g, respectively. The CeO{sub 2} powders synthesized by the CEAs are the smallest average particle size, and the highest surface area. Finally, the CeO{sub 2} prepared by the CEAs using different cerium sources and surfactant types were studied. It was found that the surface tensions of cerium solution and the type of surfactant affect the particle size of CeO{sub 2}. - Graphical Abstract: The emulsion droplet size distribution and the TEM images of CeO{sub 2} prepared by different methods: reversed micelle (RM), emulsion liquid membrane (ELM) and colloidal emulsion aphrons (CEAs). Highlights: Black-Right-Pointing-Pointer Nano-sized CeO{sub 2} was successfully prepared by three different emulsion methods. Black-Right-Pointing-Pointer The colloidal emulsion aphrons method producing CeO{sub 2} with the highest surface area. Black-Right-Pointing-Pointer The surface tensions of a cerium solution have slightly effect on the particle size. Black-Right-Pointing-Pointer The size control could be interpreted in terms of the adsorption of the surfactant.

  13. Flow of oil-in-water emulsions through orifice and venturi meters

    Microsoft Academic Search

    Rajinder Pal

    1993-01-01

    The applicability of conventional orifice and venturi meters to monitor the flow rate of oil\\/water emulsions was investigated. The discharge coefficients were determined for various unstable and surfactant-stabilized oil-in-water emulsions using a single orifice and a single venturi. The oil concentration was varied over a wide range of 0-84.32 vol %. The metering results indicate that orifice and venturi meters

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

    Microsoft Academic Search

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

    2000-01-01

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

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

    Microsoft Academic Search

    Eric Dickinson; Jianshe Chen

    1999-01-01

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

  16. On the Behavior of Nonionic Surfactants at the N-Heptane/Silica Gel Interface: Influence of the Presence of Interfacial Water Inferred from Adsorption Isotherms and Calorimetric Data.

    PubMed

    Lagerge; Keh; Partyka; Lindheimer

    2000-07-15

    The behavior of two polydisperse nonionic surfactants, poly (oxyethylene) glycol alkylphenyl ether TX-35 and TX-100, at the prewetted silica gel/n-heptane and dried silica gel/n-heptane interfaces has been compared by the determination of the average adsorption isotherms of the polydisperse surfactants and of displacement enthalpies. From HPLC experiments, we could also separately quantify the adsorption of each ethyleneoxide (EO) fractions for silica gel from the polydisperse surfactant solution. The adsorption isotherms clearly indicate an incomplete preferential adsorption of the large (EO) chains over the small ones, as well on dried silica gel as on a prehydrated sample. This preferential adsorption and its driving force follow the solubility rules of the poly(oxyethylene) glycol alkylphenyl ether in an apolar solvent and support the idea of a solubility-limited adsorption: solubility in organic solvents of the smaller (EO) chains is much more significant than that of the longer ones and hence prevents adsorption of the smaller species. Consequently, it is observed that the presence of interfacial water decreases the affinity of TX-35 molecules for the hydrophilic silica surface due to the hydration of (EO) chains. In contrast, for TX-100 adsorption after the prewetting treatment the clearest trend is a drastic increase of the adsorption ascribed to the additional solubilization (and micellization) of the TX-100 molecules in the interfacial aqueous phase. The differential molar enthalpies of displacement show a change in the adsorption mechanism, depending on the presence of molecular water on the surface. In the initial part of the adsorption isotherm, a prevailing exothermic process is obtained with prehydrated silica and suggests that hydration of the polar heads of TX-35 and the solubilization of the TX-35 in interfacial water are occurring. For higher equilibrium concentrations, the enthalpies of displacement observed with the prehydrated adsorbent become slightly lower than those obtained with dry silica gel. It may be that this difference is due to the micellization phenomenon of the surfactant species with longer EO chains in interfacial water. These features emphasize the influence of interfacial water on the adsorption of EO fractions from organic solvent. Copyright 2000 Academic Press. PMID:10873328

  17. Rheological behavior of worm-like micelles in a mixed nonionic surfactant system of a polyoxyethylene phytosterol and a glycerin fatty acid monoester.

    PubMed

    Hashizaki, Kaname; Tamaki, Nao; Taguchi, Hiroyuki; Saito, Yoshihiro; Tsuchiya, Koji; Sakai, Hideki; Abe, Masahiko

    2008-12-01

    In the present study, we examine a worm-like micelle consisting of a nonionic surfactant system of polyoxyethylene phytosterol (PhyEO(m))/glycerin fatty acid monoester (GFA-C(n))/Water (m=10, 20, 30; n=8, 10, 12) using rheological measurements looking towards potential application of the system as a gel base. Phase diagrams in the dilute region of the PhyEO(m)/GFA-C(n)/Water systems show the formation of worm-like micelles in some of the surfactant combinations. It is thought that the worm-like micelles form with the GFA-C(n) solubilized in the palisade layer of a spherical or rod-like micelle consisting of PhyEO(m), resulting in a decrease in the interfacial curvature of the molecular assembly. The rheological properties of micellar solutions were examined while changing the ratio of GFA-C(n) (R) with the total concentration of the surfactants (wt%) fixed. Steady-flow viscosity measurements in the region of worm-like micelle formation showed Newtonian flow in the low shear rate region and non-Newtonian flow at higher shear rates. This result shows that the network structure of worm-like micelles does not break in the low shear rate region, but does break in the high shear rate region. The zero-shear viscosity (eta(0)) was calculated from the steady-flow viscosity curve and was found to change dramatically with changing R value, increasing to a value 10000 times that of other values at the maximum. Thus, there is an optimal composition of surfactants which leads to the greatest entanglement of the worm-like micelles. To consider the change in eta(0) in detail, dynamic viscoelasticity measurements were carried out. Consequently, the viscoelastic behavior of the worm-like micelles was found to be similar to the Maxwell model, which represents the most basic model for a viscoelastic body, and it was shown that this worm-like micelle had a single relaxation time. Moreover, it was found that the change in eta(0) of a worm-like micelle was influenced by its mechanical strength. PMID:19043239

  18. Microfluidics with Gel Emulsions

    NASA Astrophysics Data System (ADS)

    Priest, Craig; Surenjav, Enkhtuul; Herminghaus, Stephan; Seemann, Ralf

    2006-03-01

    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 have studied online generation, organization and manipulation of gel emulsions using a variety of microchannel geometries. ``Passive'' reorganization, based on fixed channel geometries, can be supplemented by ``active'' manipulation by incorporating a ferrofluid phase. A ferromagnetic phase facilitates reorganization of liquid compartments on demand using an electromagnetic trigger. Moreover, coalescence between adjacent compartments within a gel emulsion can be induced using electrical potential. Microfluidics using gel emulsions will be well-suited for combinatorial chemistry, DNA sequencing, drug screening and protein crystallizations.

  19. Droplet-based microfluidics and the dynamics of emulsions

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    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)

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

    PubMed

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

    2013-11-01

    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

  1. Copper extraction into emulsion liquid membranes using LIX 984NC®

    Microsoft Academic Search

    Bina Sengupta; R. Sengupta; N. Subrahmanyam

    2006-01-01

    The extraction of copper from aqueous sulfate media into ELMs using the extractant LIX 984N-C was studied. Appropriately characterized emulsions on the basis of viscosity and internal drop sizes were used to study the effect of different parameters on extraction. The effects of stirring speed, surfactant concentration, pH of the external continuous phase, carrier concentration, internal phase stripping acid concentration

  2. 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

    M Kanouni; H. L Rosano; N Naouli

    2002-01-01

    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

  3. DNA interaction with cis- and trans- isomers of photosensitive surfactant

    NASA Astrophysics Data System (ADS)

    Unksov, I. N.; Kasyanenko, N. A.

    2014-12-01

    Interaction between DNA and photosensitive cationic surfactant in a solution is studied. Studies were conducted to examine the impact of the surfactant in its cis- conformation on the size of DNA molecule and also to investigate the phase behavior of the system depending on DNA and surfactant concentration. We conclude that trans- isomer of surfactant requires its smaller concentration to reach the DNA compaction compared with cis- isomer received by UV radiation of solutions. Studies of DNA-surfactant systems were performed by means of spectrophotometry and viscometry. Variation of surfactant concentration enables us to determine the precipitation zone on phase diagram. From the viscosity study it can be indicated that precipitation zone is narrower for UV-radiated surfactant and it shifts to higher surfactant concentration. Also we examine the reversibility of DNA compaction in systems with the surfactant in its trans- form.

  4. Smart enrichment and facile separation of oil from emulsions and mixtures by superhydrophobic/superoleophilic particles.

    PubMed

    Duan, Chunting; Zhu, Tang; Guo, Jing; Wang, Zhen; Liu, Xiaofang; Wang, Hao; Xu, Xun; Jin, Yan; Zhao, Ning; Xu, Jian

    2015-05-20

    The separation and removal of oil or organic pollutants from water is highly imperative. The oil phases in surfactant-free oil-in-water emulsions or in free oil/water mixtures can be smartly enriched and transported by using superhydrophobic/superoleophilic iron particles (SHIPs) under a magnetic field. For water-in-oil emulsion, SHIPs-based composite membranes selectively allow the oil to pass through. Their convenient and scalable preparation, excellent separation performance, and good reusability are of great advantages for practical applications in wastewater treatment, the cleanup of oil spills, emulsion concentration, and fuel purification. PMID:25918874

  5. Fabrication of covalently-bonded polystyrene\\/SiO 2 composites by Pickering emulsion polymerization

    Microsoft Academic Search

    Dezhong Yin; Qiuyu Zhang; Hepeng Zhang; Changjie Yin

    2010-01-01

    Pickering emulsion polymerization has attracted considerable attention in material fabrication due to its unique surfactant-free\\u000a character and versatile association of oil, water and particles for a large set of materials. In this study, SiO2 modified with Methacryloxypropyltrimethoxysilane (MPTMS) was employed to prepare Pickering emulsion, and subsequently covalently-bonded\\u000a polystyrene\\/SiO2(PS\\/SiO2) composites were synthesized by Oil-in-water Pickering emulsion polymerization. Optical micrograph, contact angle,

  6. Preparation of Al(OH)3\\/Acrylic Copolymer Latex by Emulsion Polymerization

    Microsoft Academic Search

    Eun Ju Park; Yeon Tae Jeong; Won-Ki Lee; Yeong-Soon Gal; Kwon Taek Lim

    2010-01-01

    The Al(OH)3\\/acrylic copolymer latexes were synthesized through the emulsion polymerization of acrylic monomers, butyl acrylate and 2-ethylhexyl acrylate in the presence of surface-functionalized Al(OH)3 filler particles. The polymerization was stabilized by polyoxyethylene (50) nonyl phenyl ether (NP-1050, nonionic surfactant) and ammonium (POE) alkyl aryl ether sulfate (EU-S133D, anionic surfactant) to produce stable composite latexes. The improved compatibility of Al(OH)3 surface

  7. Demulsification of a crude oil middle phase emulsion

    SciTech Connect

    Duke, R.B.

    1984-03-27

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

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

    PubMed Central

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

    2011-01-01

    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. PMID:24310496

  10. Synthesis, micellization behavior, antimicrobial and intercalative DNA binding of some novel surfactant copper(II) complexes containing modified phenanthroline ligands.

    PubMed

    Nagaraj, Karuppiah; Ambika, Subramanian; Rajasri, Shanmugasundaram; Sakthinathan, Subramanian; Arunachalam, Sankaralingam

    2014-10-01

    The novel surfactant copper(II) complexes, [Cu(ip)2DA](ClO4)21, [Cu(dpqc)2DA](ClO4)22, [Cu(dppn)2DA](ClO4)23, where ip=imidazo[4,5-f][1,10]phenanthroline, dpqc=dipyrido[3,2-a:2',4'-c](6,7,8,9-tetrahydro)phenazine, dppn=benzo[1]dipyrido[3,2-a':2',3'-c]phenazine and DA-dodecylamine, were synthesized and characterized by physico-chemical and spectroscopic methods. In these complexes 1-3, the geometry of copper metal ions was described as square pyramidal. The critical micelle concentration (CMC) value of these surfactant copper(II) complexes in aqueous solution was found out from conductance measurements. Specific conductivity data at different temperatures served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (?Gm°, ?Hm° and ?Sm°). The binding interaction of these complexes with DNA (calf thymus DNA) in Tris buffer was studied by physico-chemical techniques. In the presence of the DNA UV-vis spectrum of complexes showed red shift of the absorption band along with significant hypochromicity indicating intercalation of our complexes with nucleic acids. Competitive binding study with ethidium bromide (EB) shows that the complexes exhibit the ability to displace the nucleic acid-bound EB indicating that the complexes bind to nucleic acids in strong competition with EB for the intercalative binding site. Observed changes in the circular dichoric spectra of DNA in the presence of surfactant complexes support the strong binding of complexes with DNA. CV results also confirm this mode of binding. Some significant thermodynamic parameters of the binding of the titled complexes to DNA have also been determined. The results reveal that the extent of DNA binding of 3 was greater than that of 1 and 2. The antibacterial and antifungal screening tests of these complexes have shown good results compared to its precursor chloride complexes. PMID:25033435

  11. Association behavior of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymers with cationic surfactants in aqueous solution.

    PubMed

    Bakshi, Mandeep Singh; Sachar, Shweta; Yoshimura, Tomokazu; Esumi, Kunio

    2004-10-01

    The association behavior of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers in aqueous solution with hexadecyltrimethylammonium bromide (HTAB), tetradecyltrimethylammonium bromide (TTAB), and dimethylene bis(decyldimethylammonium bromide) (10-2-10), was studied by fluorescence, viscosity, and Krafft temperature measurements. It has been observed that (EO)18(PO)31(EO)18 interacts more strongly than (EO)2(PO)15.5(EO)2 and (EO)2.5(PO)31(EO)2.5 with HTAB/TTAB due to synergistic interactions. A stronger capability of (EO)18(PO)31(EO)18 to interact with cationic surfactants arises from the greater number of electronegative EO units (total 36 EO units) than of (EO)2(PO)15.5(EO)2 (total 4 EO units) and (EO)2.5(PO)31(EO)2.5 (total 5 EO units). The antagonistic mixing behavior of present triblock polymers has been observed with 10-2-10. A difference in the mixing behavior of the latter from that of HTAB/TTAB has been attributed to its dimeric nature, which may create steric hindrances with triblock polymer components at the head group region in the mixed state. PMID:15313658

  12. Structure and Rheology of Concentrated Emulsions

    NASA Astrophysics Data System (ADS)

    Huang, Jung-Ren; Lai, Yi-Cian; Ou, Che-Hao; Tsai, Jih-Chiang

    2015-03-01

    We construct a shearing apparatus combining light scattering and stress measurement to study the structure and rheology of concentrated monodisperse emulsions. The emulsions are subjected to oscillatory shear of variable amplitude and frequency. The light scattering data reflect droplet deformation as well as shear history-dependent inter-droplet structures. The stress measurements display pseudoplasticity near zero shear rate and shear-thinning behavior at finite shear rates. In addition, the time-resolved, synchronous measurement of light scattering and rheology reveal detailed information about the complex structure-rheology relationship of emulsions. Shear disorders the droplets at low and high shear rates but induces order at medium shear rates. Furthermore, the effective viscosity increases as the degree of inter-droplet order decreases. This work is supported by Taiwan MOST Grant 100-2112-M-003-001-MY3.

  13. Magnetoresistive Emulsion Analyzer

    PubMed Central

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

    2013-01-01

    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

  14. Dynamic film and interfacial tensions in emulsion and foam systems

    SciTech Connect

    Kim, Y.H.; Koczo, K.; Wasan, D.T. [Illinois Inst. of Tech., Chicago, IL (United States). Chemical Engineering Dept.] [Illinois Inst. of Tech., Chicago, IL (United States). Chemical Engineering Dept.

    1997-03-01

    In concentrated fluid dispersions the liquid films are under dynamic conditions during film rupture or drainage. Aqueous foam films stabilized with sodium decylsulfonate and aqueous emulsion films stabilized with the nonionic Brij 58 surfactant were formed at the tip of a capillary and the film tension was measured under static and dynamic conditions. In the stress relaxation experiments the response of the film tension to a sudden film area expansion was studied. These experiments also allowed the direct measurement of the Gibbs film elasticity. In the dynamic film tension experiments, the film area was continuously increased by a constant rate and the dynamic film tension was monitored. The measured film tensions were compared with the interfacial tensions of the respective single air/water and oil/water interfaces, which were measured using the same radius of curvature, relative expansion, and expansion rate as in the film studies. It was found that under dynamic conditions the film tension is higher than twice the single interfacial tension (IFT) and a mechanism was suggested to explain the difference. When the film, initially at equilibrium, is expanded and the interfacial area increases, a substantial surfactant depletion occurs inside the film. As a result, the surfactant can be supplied only from the adjoining meniscus (Plateau border) by surface diffusion, and the film tension is controlled by the diffusion and adsorption of surfactant in the meniscus. The results have important implications for the stability and rheology of foams and emulsions with high dispersed phase ratios (polyhedral structure).

  15. Preparation of double Pickering emulsions stabilized by chemically tailored nanocelluloses.

    PubMed

    Cunha, Ana G; Mougel, Jean-Bruno; Cathala, Bernard; Berglund, Lars A; Capron, Isabelle

    2014-08-12

    Nanocelluloses are bio-based nanoparticles of interest as stabilizers for oil-in-water (o/w) Pickering emulsions. In this work, the surface chemistry of nanocelluloses of different length, nanofibrillated cellulose (NFC, long) and cellulose nanocrystals (CNC, short), was successfully tailored by chemical modification with lauroyl chloride (C12). The resulting nanofibers were less hydrophilic than the original and able to stabilize water-in-oil (w/o) emulsions. The combination of the two types of nanocelluloses (C12-modified and native) led to new surfactant-free oil-in-water-in-oil (o/w/o) double emulsions stabilized by nanocellulose at both interfaces. Characterization was performed with respect to droplet size distribution, droplet stability over time, and stability after centrifugation. Nanocellulose-based Pickering emulsions can be designed with a substantial degree of control, as demonstrated by the stability of the chemically tailored NFC double emulsions. Furthermore, it was demonstrated that increased nanofiber length leads to increased stability. PMID:25046221

  16. Systematic characterization of oil-in-water emulsions for formulation design

    Microsoft Academic Search

    I. Roland; G. Piel; L. Delattre; B. Evrard

    2003-01-01

    Oil-in-water emulsions varying in surfactant concentration and manufacturing process were prepared. About 10 experiments were performed to characterize them. The goal of this research was to find out which tests should systematically be carried out to assess efficiently the stability and the properties of an emulsified preparation. Thus, formulation design requires at least the measurement of the droplet size, the

  17. Aqueous emulsion containing fluorous cobalt species in supercritical CO2 for catalytic air oxidation of toluene.

    PubMed

    Zhu, Jie; Robertson, Alan; Tsang, Shik Chi

    2002-09-21

    An aqueous emulsion containing ionic Co2+ and Br- species stabilised by fluorous surfactant-like species in supercritical CO2-air mixture acts as a nano-reactor with excellent interfacial contacts of all necessary hydrophilic/hydrophobic species, which renders safe operation of catalytic aerial oxidation of toluene at high yields. PMID:12357771

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

    NASA Astrophysics Data System (ADS)

    Gurevich, Leonid; Fojan, Peter

    2012-02-01

    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.

  19. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-07-01

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

  20. Associating polymer and polymer-surfactant additives for suppression of aerosol formation

    NASA Astrophysics Data System (ADS)

    Ergungor, Zeynep

    High molecular weight polymers can suppress the breakup of low-viscosity liquids by increasing the elasticity, particularly the extensional viscosity of the system. Recently, polyisobutylene (PIB) and polyethylene oxide (PEO) have been successfully applied as mist control agents for straight oil (PIB) and oil-in-water emulsion types machining fluids (PEO). However, the high shear stresses experienced in metal-working operations cause mechanical degradation of high molecular weight polymers. This necessitates periodic additions of fresh polymer to sustain effective control of misting. One solution to this problem is the development of self-associative polymer and polymer-surfactant systems that achieve the rheological effects of high molecular weight linear polymers that exhibit improved antimisting effectiveness at low concentrations, and improved shear stability due to structure regeneration. First, laboratory atomization experiments are performed to show that the antimisting effectiveness of PEO is greatly enhanced by interactions between PEO and certain surfactants. Actually, the effectiveness of PEO-surfactant association depends on the surfactant chemistry. Sodium dodecyl benzyl sulfonate (SDBS) exhibits a strong structure-forming interaction with PEO, leading to excellent rheological properties for mist suppression, while sodium dodecyl sulfate (SDS) interactions with PEO have less influence on rheology and drop size. Atomization, shear and elongational viscometry, as well as dynamic light scattering and conductivity experiments are employed to probe the effects of these interactions on the drop size, rheology and structure of these systems. Second, self-association behavior of a triblock copolymer of polystyrene-polybutadiene-polystyrene in a selective solvent system, heptane and toluene, is investigated. Shear viscosity measurements revealed the formation of associative structures as the copolymer concentration increases in the more selective solvent. However, atomization experiments did not show any increase in aerosol drop size although elongational viscosity measurements confirmed the copolymer's substantial contribution to the elasticity of the system. Thus, the mechanism for suppression of liquid breakup due to viscoelasticity is absent in these fluids.

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

    PubMed

    Nikolakakis, Ioannis; Malamataris, Stavros

    2014-05-01

    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

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

    SciTech Connect

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

    1994-10-15

    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.

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

    Microsoft Academic Search

    Recep Ali Kumbasar

    2010-01-01

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

  4. Emulsions for interfacial filtration.

    SciTech Connect

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

    2006-11-01

    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.

  5. Release of surfactant cargo from interfacially-active halloysite clay nanotubes for oil spill remediation.

    PubMed

    Owoseni, Olasehinde; Nyankson, Emmanuel; Zhang, Yueheng; Adams, Samantha J; He, Jibao; McPherson, Gary L; Bose, Arijit; Gupta, Ram B; John, Vijay T

    2014-11-18

    Naturally occurring halloysite clay nanotubes are effective in stabilizing oil-in-water emulsions and can serve as interfacially-active vehicles for delivering oil spill treating agents. Halloysite nanotubes adsorb at the oil-water interface and stabilize oil-in-water emulsions that are stable for months. Cryo-scanning electron microscopy (Cryo-SEM) imaging of the oil-in-water emulsions shows that these nanotubes assemble in a side-on orientation at the oil-water interface and form networks on the interface through end-to-end linkages. For application in the treatment of marine oil spills, halloysite nanotubes were successfully loaded with surfactants and utilized as an interfacially-active vehicle for the delivery of surfactant cargo. The adsorption of surfactant molecules at the interface serves to lower the interfacial tension while the adsorption of particles provides a steric barrier to drop coalescence. Pendant drop tensiometry was used to characterize the dynamic reduction in interfacial tension resulting from the release of dioctyl sulfosuccinate sodium salt (DOSS) from halloysite nanotubes. At appropriate surfactant compositions and loadings in halloysite nanotubes, the crude oil-saline water interfacial tension is effectively lowered to levels appropriate for the dispersion of oil. This work indicates a novel concept of integrating particle stabilization of emulsions together with the release of chemical surfactants from the particles for the development of an alternative, cheaper, and environmentally-benign technology for oil spill remediation. PMID:25346266

  6. Chemical demulsification of petroleum emulsions using oil-soluable demulsifiers

    Microsoft Academic Search

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

    1991-01-01

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

  7. Characteristic features of heterophase polymerisation of styrene with simultaneous formation of surfactants at the interface

    NASA Astrophysics Data System (ADS)

    Prokopov, Nikolai I.; Gritskova, Inessa A.

    2001-09-01

    Data on the heterophase polymerisation of styrene under conditions of surfactant formation at the monomer-water interface are generalised. A new, in principle, approach is proposed the essence of which is to obtain a monomer emulsion simultaneously with the synthesis of an emulsifier at the monomer-water interface and with initiation of the polymerisation in the interfacial layer. The preparation of surfactants at the interface allows one to control efficiently the degree of dispersion and the stability of the emulsions formed. By varying the nature of the acid and the metal counter-ion used in the surfactant synthesis at the interface, it is possible to change the interfacial tension, to influence the microemulsification, disintegration of the monomer, and the formation of structure of interfacial adsorption layers. The mechanism of formation of polymer-monomeric particles as well as their diameter and size distribution depend substantially on the solubility of the resulting surfactants in water. The bibliography includes 47 references.

  8. Development of High Sensitivity Nuclear Emulsion and Fine Grained Emulsion

    NASA Astrophysics Data System (ADS)

    Kawahara, H.; Asada, T.; Naka, T.; Naganawa, N.; Kuwabara, K.; Nakamura, M.

    2014-08-01

    Nuclear emulsion is a particle detector having high spacial resolution and angular resolution. It became useful for large statistics experiment thanks to the development of automatic scanning system. In 2010, a facility for emulsion production was introduced and R&D of nuclear emulsion began at Nagoya university. In this paper, we present results of development of the high sensitivity emulsion and fine grained emulsion for dark matter search experiment. Improvement of sensitivity is achieved by raising density of silver halide crystals and doping well-adjusted amount of chemicals. Production of fine grained emulsion was difficult because of unexpected crystal condensation. By mixing polyvinyl alcohol (PVA) to gelatin as a binder, we succeeded in making a stable fine grained emulsion.

  9. Emulsion gel beads of calcium pectinate capable of floating on the gastric fluid: effect of some additives, hardening agent or coating on release behavior of metronidazole.

    PubMed

    Sriamornsak, Pornsak; Thirawong, Nartaya; Puttipipatkhachorn, Satit

    2005-03-01

    Emulsion gel (EMG) beads of calcium pectinate capable of floating in the gastric condition were developed using an emulsion-gelation method and their release properties were investigated. Attempts to modify the drug release were made by applying some additives into the starting solution prior to bead formation, by hardening with glutaraldehyde, and by coating with polymer. The metronidazole-loaded EMG beads were found to float on simulated gastric fluid. Increasing the drug to pectin ratio in the beads slowed the drug release from the conventional and the EMG beads. However, the drug release from these beads was rapid, i.e., about 80% of drug loading released within 20-80 min. The additives (PEG10000, glyceryl monostearate and Eudragit L) had a slight, insignificant, effect on the drug release. Using 2% glutaraldehyde as a hardening agent prolonged the drug release. Coating the beads with Eudragit RL significantly sustained the drug release while the beads remained buoyant. The results suggest that EMG beads are suitable as a carrier for intragastric floating drug delivery and that their release behaviour could be modified by hardening with glutaraldehyde or by coating with Eudragit RL. PMID:15734303

  10. Structural characteristics of polyelectrolyte-surfactant complexes in aqueous solution

    NASA Astrophysics Data System (ADS)

    Nause, Richard; Strey, Helmut H.; Hoagland, David A.

    2001-03-01

    When polyelectrolytes and surfactants of opposite charge are mixed at a stoichiometric charge ratio, they self-assemble into ordered complexes. This contribution reports the self-assembly behavior of polyelectrolyte-surfactant complexes in aqueous solution. Of specific importance are the thermodynamics associated with polyelectrolyte-surfactant interactions, the morphological sensitivity to surfactant concentration, and the overall effect of ionic strength on the aggregation process. We have chosen to study the interaction of a model polyelectrolyte [sodium poly(styrene sulfonate)] with cetyltrimethylammonium chloride (CTAC), a cationic surfactant. We utilize turbidity, microcalorimetry, and small angle X-ray scattering to investigate the self-assembly process and specifically identify the factors that govern the aggregation behavior of polymer surfactant systems. We eventually plan to develop strategies to better control and predict the behavior of these systems.

  11. Potential commercial applications of microbial surfactants.

    PubMed

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

    2000-05-01

    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

  12. Spreading of an Oil-in-Water Emulsion on a Glass Plate: Phase Inversion and Pattern Formation.

    PubMed

    Deblais, A; Harich, R; Bonn, D; Colin, A; Kellay, H

    2015-06-01

    Rigid blade coating of glass plates by oil-in-water emulsions stabilized by surfactants is studied. Complete surface coverage is obtained only for speeds exceeding a threshold velocity dependent on the height between the blade end and the surface. Below this threshold, the emulsion can be inverted in the vicinity of the blade. The inversion dynamics of the oil-in-water emulsion and the deposition patterns induced by this phase inversion are studied using a microscope mounted set up. We show that these dynamics are universal for different volume fractions and deposition velocities. This inversion as well as the destabilization of the emulsion film deposited at high speeds gives rise to different patterns on the glass surface. These patterns are discussed in terms of the emulsion characteristics as well as the deposition velocity. PMID:26000801

  13. Micellization of true amphoteric surfactants.

    PubMed

    Li, Yunxiang; Holmberg, Krister; Bordes, Romain

    2013-12-01

    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

  14. Theoretical and simulations-based modeling of micellization in linear and branched surfactant systems

    E-print Network

    Mendenhall, Jonathan David

    2012-01-01

    Surfactants are chemically-heterogeneous molecules possessing hydrophilic (head) and hydrophobic (tail) moieties. This dual nature of surfactants leads to interesting phase behavior in aqueous solution as a function of ...

  15. Characterization and Demulsification of Water-in-crude Oil Emulsions

    NASA Astrophysics Data System (ADS)

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

    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.

  16. Mixed reverse micelles facilitated downstream processing of lipase involving water-oil-water liquid emulsion membrane.

    PubMed

    Bhowal, Saibal; Priyanka, B S; Rastogi, Navin K

    2014-01-01

    Our earlier work for the first time demonstrated that liquid emulsion membrane (LEM) containing reverse micelles could be successfully used for the downstream processing of lipase from Aspergillus niger. In the present work, we have attempted to increase the extraction and purification fold of lipase by using mixed reverse micelles (MRM) consisting of cationic and nonionic surfactants in LEM. It was basically prepared by addition of the internal aqueous phase solution to the organic phase followed by the redispersion of the emulsion in the feed phase containing enzyme, which resulted in globules of water-oil-water (WOW) emulsion for the extraction of lipase. The optimum conditions for maximum lipase recovery (100%) and purification fold (17.0-fold) were CTAB concentration 0.075 M, Tween 80 concentration 0.012 M, at stirring speed of 500 rpm, contact time 15 min, internal aqueous phase pH 7, feed pH 9, KCl concentration 1 M, NaCl concentration 0.1 M, and ratio of membrane emulsion to feed volume 1:1. Incorporation of the nonionic surfactant (e.g., Tween 80) resulted in remarkable improvement in the purification fold (3.1-17.0) of the lipase. LEM containing a mixture of nonionic and cationic surfactants can be successfully used for the enhancement in the activity recovery and purification fold during downstream processing of enzymes/proteins. PMID:24930827

  17. Amphoteric water-in-oil self-inverting polymer emulsion

    SciTech Connect

    Lipowski, S. A.

    1985-11-12

    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.

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

    PubMed

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

    2014-10-13

    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 (V(h)) indicated that there is a relationship between V(h) 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 V(h) 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

  19. Phase diagram approach to evaporation from emulsions with n oil compounds.

    PubMed

    Friberg, Stig E

    2009-03-26

    The initial evaporation path was calculated for an emulsion of water and a multicomponent oil phase under the following conditions. The computations were based on the phase diagram of the emulsion system combined with an algebraic system to extract information from phase diagrams to facilitate the mathematical treatment. An inherent consequence of the use of the phase diagram as a basis to calculate an evaporation path is the condition of equilibrium between the phases in the emulsion as well as between the vapor and the condensed phases. In addition to this fundamental limitation, the features of the phase diagram of the actual emulsion were restricted as follows. There is no solubility of significance in the water of either the oil or of the surfactant. The nonaqueous compounds display extensive mutual solubility with the solutions being close to ideal. This solution of the nonaqueous compounds does not dissolve nor solubilize water to a degree to affect the calculations in the stage of evaporation treated; an emulsion in the two-phase region of lowest surfactant content. PMID:19673136

  20. Dynamics of Unjammed Emulsions

    NASA Astrophysics Data System (ADS)

    Guerra, Rodrigo; Kodger, Thomas; Weitz, David

    2014-03-01

    Light scattering and NMR densitometry measurements of quiescent emulsions have shown that amorphous packings of soft, repulsive droplets unjam at osmotic pressures 105 times larger than the typical droplet thermal energy density: 3kB/T 4 ?R3. This transition corresponds to the pressure at which the thermal fluctuations of individual droplet positions match the yield strain of the packing and drive the fluidization of the material. We use confocal microscopy to investigate the microscopic dynamics of this fluid-like phase and find them to be fundamentally different from those of conventional glass-forming liquids; cage-breaking dynamics are not evident from droplet mean squared displacements and the effective viscosity of the emulsion, though 105 larger than the background fluid, appears largely insensitive to the confining pressure.

  1. Sorption of nonionic organic compounds in soil-water systems containing a micelle-forming surfactant

    SciTech Connect

    Sun, S.; Inskeep, W.P.; Boyd, S.A. [Montana State Univ., Bozeman, MT (United States). Dept. of Plant, Soil and Environmental Science; [Michigan State Univ., East Lansing, MI (United States). Dept. of Crop and Soil Science

    1994-12-31

    The solubility enhancement of nonionic organic compounds (NOCs) by surfactants may represent an important tool in chemical and biological remediation of contaminated soils. In aqueous systems, the presence of dissolved surfactant emulsions or micelles may enhance the solubility of NOCs by acting as a hydrophobic partitioning phase for the NOCs. However, most environmental remediation efforts involve soil-water or sediment-water systems, where surfactant molecules may also interact with the solid phase. An understanding of the effect of surfactants on the sorption and distribution of NOCs in soil or sediment environments will provide an essential basis for utilizing surfactants in environmental remediation. In this study, the authors examined the effect of a micelle-forming surfactant (Triton X-100) on the sorption of 2,2{prime},4,4{prime},5,5{prime}-PCB, 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (p,p{prime}-DDT) and 1,2,4-trichlorobenzene (1,2,4-TCB). A conceptual model, which accurately describes the functional dependence of K* on Triton X-100 concentration, was developed based on the partition coefficients of these NOCs by soil, soil-surfactant, surfactant monomer and surfactant micelle phases. This model can be further modified to provide quantitative prediction of K* of a given NOC at different surfactant concentrations.

  2. Rheology of siloxane-stabilized water in silicone emulsions.

    PubMed

    Forster, A H; Herrington, T M

    1997-08-01

    Using silicone copolymers in personal care products can improve the aesthetic performance of formulations. During their manufacture, distribution and topical application they are subject to various mechanical stresses. In this study rheology was used to measure their effects. A number of water in silicone (w/Si) emulsions were prepared in which the oil phase consisted of cyclomethicone. The surfactant used was a branched type silicone copolymer. Both viscoelastic and viscometry measurement were performed on model systems and on commercial products. Experimental data were obtained using a Bohlin rheometer. The measurements were taken applying shear rates in the range of 0.46-58 l s-1 and for the strain sweep frequencies of 0.1 Hz, 1 Hz and 10 Hz were applied. Oscillation tests were performed in the 0.1 Hz to 10 Hz range. All measurements were taken at 35deg;C, representing the approximate temperature encountered during topical application. The effect of surfactant concentration on viscoelastic properties was examined. It was shown that with increasing surfactant concentration the elastic moduli G' and the viscous moduli G" increased. Furthermore, the emulsions showed a transition from a predominantly elastic to a predominantly viscous response as the surfactant concentration increased. The effect of varying the water phase volume fraction on viscometry and viscoelastic measurements was also examined. With increasing water phase volume fraction the viscosity of the emulsions, as well as the yield stress, increased. The Cross and Sisko models were applied. From the Dougherty and Krieger equation phieff was calculated. It was found the the data derived from the Sisko model gave more reliable results. Results obtained from commercial samples showed a high proportion of elasticity; oscillation tests and viscometry experiments suggested that tumbling had the biggest impact on the theological profiles; viscosity, eta, shear stress, sigma, elastic module, G', and dynamic viscosity, eta', dropped to a minimum in these samples. Results from the two commercial samples were compared and it was observed that, although both were w/o emulsions, different rheological behaviour could be observed. PMID:18507635

  3. Bituminous emulsions and their characterization by atomic force microscopy

    PubMed

    Loeber; Alexandre; Muller; Triquigneaux; Jolivet; Malot

    2000-04-01

    We present a new method for observing oil-in-water emulsions with a continuous water phase and a dispersed bitumen phase. The fine polydispersed bitumen micelles were adsorbed to an atomically smooth mica substrate and imaged in solution by atomic force microscopy in a liquid cell. The height of the adsorbed bitumen sheet in wet and dry states can be measured and the homogeneity of film formation by coalescence can be determined. Localization of surfactant onto and between bitumen micelles is also visualized. PMID:10781204

  4. Membrane-Integrated Glass Capillary Device for Preparing Small-Sized Water-in-Oil-in-Water Emulsion Droplets.

    PubMed

    Akamatsu, Kazuki; Kanasugi, Shosuke; Nakao, Shin-Ichi; Weitz, David A

    2015-06-30

    In this study, a membrane-integrated glass capillary device for preparing small-sized water-in-oil-in-water (W/O/W) emulsion droplets is demonstrated. The concept of integrating microfluidics to prepare precise structure-controlled double emulsion droplets with the membrane emulsification technique provides a simple method for preparing small-sized and structure-controlled double emulsion droplets. The most important feature of the integrated device is the ability to decrease droplet size when the emulsion droplets generated at the capillary pass through the membrane. At the same time, most of the oil shell layer is stripped away and the resultant double emulsion droplets have thin shells. It is also demonstrated that the sizes of the resultant double emulsion droplets are greatly affected by both the double emulsion droplet flux through membranes and membrane pore size; when the flux is increased and membrane pore size is decreased, the generated W/O/W emulsion droplets are smaller than the original. In situ observation of the permeation behavior of the W/O/W emulsion droplets through membranes using a high-speed camera demonstrates (1) the stripping of the middle oil phase, (2) the division of the double emulsion droplets to generate two or more droplets with smaller size, and (3) the collapse of the double emulsion droplets. The first phenomenon results in a thinner oil shell, and the second division phenomenon produces double emulsion droplets that are smaller than the original. PMID:26057203

  5. SEPARATIONS Phase Separation of Liquid Mixtures in the Presence of Surfactants

    E-print Network

    Vladimirova, Natalia

    SEPARATIONS Phase Separation of Liquid Mixtures in the Presence of Surfactants Rajan Gupta, Roberto of a partially miscible liquid mixture as it phase separates. On the other hand, when the same mixture of these results can be found in any liquid- liquid operation involving phase separation, both when emulsions

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

    Microsoft Academic Search

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

    1980-01-01

    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

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

    Microsoft Academic Search

    J. S. Johnson; C. G. Westmoreland

    1982-01-01

    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

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

    PubMed

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

    2002-12-01

    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

  9. Self-Organized Assemblies of Surfactants Derived from Ethanolamines

    Microsoft Academic Search

    Partha Mukherjee; Sukalyan Dash; Sabita Patel; Bijay K. Mishra

    2012-01-01

    The aggregation behavior of some novel functional surfactants (synthesized from ethanolamines and alkyl bromides) in aqueous medium and on water-air interface has been investigated. Single-tailed surfactants derived from quaternization of triethanol amine and tetradecyl and hexadecyl bromide form micelles with CMC values around 0.07–0.5 mM while the gemini surfactants derived from diethanol amine, hexadecyl bromide and dibromoalkanes are found to aggregate

  10. Development of stable flaxseed oil emulsions as a potential delivery system of ?-3 fatty acids.

    PubMed

    Goyal, Ankit; Sharma, Vivek; Upadhyay, Neelam; Singh, A K; Arora, Sumit; Lal, Darshan; Sabikhi, Latha

    2015-07-01

    The objective of the present study was to develop a stable flaxseed oil emulsion for the delivery of omega-3 (?-3) fatty acids through food fortification. Oil-in-water emulsions containing 12.5 % flaxseed oil, 10 % lactose and whey protein concentrate (WPC)-80 ranging from 5 to 12.5 % were prepared at 1,500, 3,000 and 4,500 psi homogenization pressure. Flaxseed oil emulsions were studied for its physical stability, oxidative stability (peroxide value), particle size distribution, zeta (?)-potential and rheological properties. Emulsions homogenized at 1,500 and 4,500 psi pressure showed oil separation and curdling of WPC, respectively, during preparation or storage. All the combinations of emulsions (homogenized at 3,000 psi) were physically stable for 28 days at 4-7?ºC temperature and did not show separation of phases. Emulsion with 7.5 % WPC showed the narrowest particle size distribution (190 to 615 nm) and maximum zeta (?)-potential (-33.5 mV). There was a slight increase in peroxide value (~20.98 %) of all the emulsions (except 5 % WPC emulsion), as compared to that of free flaxseed oil (~44.26 %) after 4 weeks of storage. Emulsions showed flow behavior index (n) in the range of 0.206 to 0.591, indicating higher shear thinning behavior, which is a characteristic of food emulsions. Results indicated that the most stable emulsion of flaxseed oil (12.5 %) can be formulated with 7.5 % WPC-80 and 10 % lactose (filler), homogenized at 3,000 psi pressure. The formulated emulsion can be used as potential omega-3 (?-3) fatty acids delivery system in developing functional foods such as pastry, ice-creams, curd, milk, yogurt, cakes, etc. PMID:26139890

  11. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-07-01

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

  12. Local anesthetics, antipsychotic phenothiazines, and cationic surfactants shut down intracellular reactions through membrane perturbation in yeast.

    PubMed

    Uesono, Yukifumi; Araki, Tomoyuki; Toh-E, Akio

    2008-11-01

    High osmolarity and glucose deprivation cause rapid shutdowns of both actin polarization and translation initiation in yeast. Like these stresses, administration of local anesthetics and of antipsychotic phenothiazines caused similar responses. All these drugs have amphiphilic structures and formed emulsions and permeabilized the cell membrane, indicating that they have the same features as a surfactant. Consistently with this, surfactants induced responses similar to those of local anesthetics and phenothiazines. Benzethonium chloride, a cationic surfactant, showed a more potent shutdown activity than phenothiazines, whereas SDS, an anionic surfactant, transiently depolarized actin without inhibiting translation initiation, suggesting that a cationic charge in the amphiphile is important to the shutdown of both reactions. The clinical drugs and the cationic surfactants at low concentrations caused shutdown without membrane permeabilization, suggesting that these compounds and stresses activate shutdown, via perturbation rather than disruption of the cell membrane. PMID:18997430

  13. pH-Dependent Aggregation Behavior of a Sugar-Amine Gemini Surfactant in Water: Vesicles, Micelles, and Monolayers of Hexane1,6-bis(hexadecyl-1?-deoxyglucitylamine)

    Microsoft Academic Search

    Mark Bergsma; Matthew L. Fielden; Jan B. F. N. Engberts

    2001-01-01

    The pH-dependent aggregation behavior of one representative of a recently described series of sugar-amine gemini surfactants has been investigated. The surface tension (?) and turbidity of hexane-1,6-bis(hexadecyl-1?-deoxyglucitylamine) drop steeply between pH 5.5 and 4.0, consistent with a vesicle-to-micelle transition. The critical micelle concentration (cmc) at low pH (3.0) was determined by surface tension measurements to be 1×10?3 M. This value

  14. Structural analysis and adsorbability onto the corneal epithelial cells-model interface of vitamin nano-emulsions.

    PubMed

    Matsuki, Maiko; Miyake, Miyuki; Ogura, Taku; Hyodo, Ryo; Tobori, Norio; Sakai, Hideki; Glatter, Otto

    2014-01-01

    O/W nano-emulsions can be used as effective drug carriers of hydrophobic active ingredients in an aqueous solution, because nano-emulsions are comparatively stable and their structure can be controlled by changing the compositions and the preparation methods. In this paper, we focused on vitamin A and its derivatives (VA), which are among the widely-used lipophilic active ingredients, and tried to develop the nano-emulsions, which can bring out the efficiency of VA for the healing of injured corneas, with the detailed structural analysis of them using the small-angle X-ray scattering (SAXS) method. As a result, we elucidated that the nano-emulsions bearing the hydrophobic oil/water interface can be prepared by decreasing the surfactant concentration against vitamins. Moreover, we clarified that the nano-emulsions composed of lower surfactant concentration tend to adsorb VA onto the corneal epithelial cells-model interface. Therefore it is necessary to prepare the nano-emulsions, which have the hydrophobic oil/water interface for improving the adsorbability onto cell membranes. PMID:25099912

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

    DOEpatents

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

    1982-01-01

    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.

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

    DOEpatents

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

    1980-08-20

    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.

  17. Preparation of polystyrene latex particles by ?-rays-induced emulsifier-free emulsion polymerization

    NASA Astrophysics Data System (ADS)

    Wang, Xinbo; Zhang, Zhicheng

    2006-09-01

    Monodisperse polystyrene latex particles were prepared by 60Co- ?-ray radiation-induced emulsifier-free emulsion polymerization with the use of surfactant monomer at room temperature. The surfactant monomer 10(9)-hydroxyl-9(10)-allyl ether octadecanoic acid (HAEOA) was synthesized and characterized by FT-IR and 1H-NMR spectra. TEM was used to characterize the polystyrene latex particles. HAEOA acted as not only a comonomer but also a stabilizer to copolymerize with styrene and stabilize the polystyrene latex particles. Kinetics analysis shows that there is no constant rate stage which seems to indicate a droplet nucleation mechanism.

  18. Emulsion/Surface Interactions from Quiescent Quartz Crystal Microbalance Measurements with an Inverted Sensor.

    PubMed

    Mafi, Roozbeh; Pelton, Robert H

    2015-07-01

    Interactions of three oil-in-water emulsion types with polystyrene-coated quartz crystal microbalance (QCM) sensor surfaces were probed with the QCM cell in both the conventional orientation (i.e., polystyrene surface on the bottom, "looking up") and the inverted orientation (polystyrene on top interior surface of sensor chamber, "looking down"). With the conventionally oriented QCM sensors, the adsorption of soluble and/or dispersed species quickly gave steady-state frequency and dissipation outputs. By contrast, the inverted sensors gave changing responses at long times because of the gravity driven buildup of a viscous consolidation layer next to but not necessarily bound to the sensor surface. Three emulsion types (a simple hexadecane/phosphatidylcholine emulsion, 2% homogenized milk, and a diluted commercial ophthalmic emulsion) displayed a wide range of behaviors. We propose that quiescent QCM measurement made with an inverted sample chamber is a new approach to probing emulsion behaviors near solid surfaces. PMID:26083783

  19. Preparation of solid lipid nanoparticles from W/O/W emulsions: preliminary studies on insulin encapsulation.

    PubMed

    Gallarate, Marina; Trotta, Michele; Battaglia, Luigi; Chirio, Daniela

    2009-08-01

    A method to produce solid lipid nanoparticles (SLN) from W/O/W multiple emulsions was developed applying the solvent-in-water emulsion-diffusion technique. Insulin was chosen as hydrophilic peptide drug to be dissolved in the acidic inner aqueous phase of multiple emulsions and to be consequently carried in SLN. Several partially water-miscible solvents with low toxicity were screened in order to optimize emulsions and SLN composition, after assessing that insulin did not undergo any chemical modification in the presence of the different solvents and under the production process conditions. SLN of spherical shape and with mean diameters in the 600-1200 nm range were obtained by simple water dilution of the W/O/W emulsion. Best results, in terms of SLN mean diameter and encapsulation efficiencies, were obtained using glyceryl monostearate as lipid matrix, butyl lactate as a solvent, and soy lecithin and Pluronic F68 as surfactants. Encapsulation efficiencies up to 40% of the loaded amount were obtained, owing to the actual multiplicity of the system; the use of multiple emulsion-derived SLN can be considered a useful strategy to encapsulate a hydrophilic drug in a lipid matrix. PMID:18785076

  20. Development of eco-friendly submicron emulsions stabilized by a bio-derived gum.

    PubMed

    Pérez-Mosqueda, Luis María; Ramírez, Pablo; Trujillo-Cayado, Luis Alfonso; Santos, Jenifer; Muñoz, José

    2014-11-01

    Many traditional organic solvents are being gradually replaced by ecofriendly alternatives. D-Limonene is a terpenic (bio)-solvent that fulfils the requirements to be considered a green solvent. D-Limonene sub-micron emulsions suffer from Ostwald ripening destabilization. In this study, we examined the influence of the addition of a natural gum (rosin gum) to D-limonene in order to prevent Ostwald ripening. This contribution deals with the study of emulsions formulated with a mixture of D-limonene and rosin gum as dispersed phase and Pluronic PE9400 as emulsifier. The procedure followed for the development of these formulations was based on the application of product design principles. This led to the optimum ratio rosin gum/D-limonene and subsequently to the optimum surfactant concentration. The combination of different techniques (rheology, laser diffraction and multiple light scattering) was demonstrated to be a powerful tool to assist in the prediction of the emulsions destabilization process. Not only did the addition of rosin gum highly increase the stability of these emulsions by inhibiting the Ostwald ripening, but it also reduced the emulsions droplet size. Thus, we found that stable sub-micron D-limonene-in-water emulsions have been obtained in the range 3-6 wt% Pluronic PE-9400 by means of a single-step rotor/stator homogenizing process. PMID:25454661

  1. Effect of Hydrotropic Salt on the Assembly Transitions and Rheological Responses of Cationic Gemini Surfactant Solutions

    E-print Network

    Huang, Jianbin

    ReceiVed: August 17, 2007; In Final Form: NoVember 18, 2007 Cationic gemini surfactant dimethylene-1 of sodium salicylate (NaSal) on the assembly formation and transition of this cationic gemini surfactant to explore the interaction between gemini surfactants and hydrotropic salts. The rich aggregation behavior

  2. Microstructure, morphology and lifetime of armored bubbles exposed to surfactants

    E-print Network

    Anand Bala Subramaniam; Cecile Mejean; Manouk Abkarian; Howard A. Stone

    2006-02-16

    We report the behavior of particle-stabilized bubbles (armored bubbles) when exposed to various classes and concentrations of surfactants. The bubbles are non-spherical due to the jamming of the particles on the interface and are stable to dissolution prior to the addition of surfactant. We find that the dissolving bubbles exhibit distinct morphological, microstructural, and lifetime changes, which correlate with the concentration of surfactant employed. For low concentrations of surfactant an armored bubble remains non-spherical while dissolving, while for concentrations close to and above the surfactant CMC a bubble reverts to a spherical shape before dissolving. We propose a microstructural interpretation, supported by our experimental observations of particle dynamics on the bubble interface, that recognizes the role of interfacial jamming and stresses in particle stabilization and surfactant-mediated destabilization of armored bubbles.

  3. Solution properties and electrospinning of phosphonium gemini surfactants.

    PubMed

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

    2014-06-14

    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

  4. Dynamic Surface Tension of Aqueous Surfactant Solutions 8. Effect of Spacer on Dynamic Properties of Gemini Surfactant Solutions

    Microsoft Academic Search

    Milton J. Rosen; Li D. Song

    1996-01-01

    Two series of cationic surfactants, each with two hydrophilic and two hydrophobic groups in the molecule (“gemini” surfactants), have been synthesized. One series has a rigid, hydrophobic spacer, and the second, a flexible, more hydrophilic one. The dynamic behavior of their aqueous solutions has been studied by the maximum bubble pressure method. Thenvalue (dynamic adsorption parameter) in both series increases

  5. Preparation of Pickering emulsions stabilized by metal organic frameworks using oscillatory woven metal micro-screen.

    PubMed

    Sabouni, R; Gomaa, H G

    2015-05-27

    Uniform Pickering emulsions stabilized by metal organic frameworks (MOFs) MIL-101 and ZIF-8 nanoparticles (NPs) were successfully prepared using an oscillatory woven metal microscreen (WMMS) emulsification system in the presence and the absence of surfactants. The effects of operating and system parameters including the frequency and amplitude of oscillation, the type of nano-particle and/or surfactant on the droplet size and coefficient of variance of the prepared emulsions are investigated. The results showed that both the hydrodynamics of the system and the hydrophobic/hydrophilic nature of the NP influenced the interfacial properties of the oil-water interface during droplet formation and after detachment, which in turn affected the final droplet size and distribution. Comparison between the measured and predicted droplet size using a simple torque balance (TB) model is discussed. PMID:25953152

  6. Programmed emulsions for sodium reduction in emulsion based foods.

    PubMed

    Chiu, Natalie; Hewson, Louise; Fisk, Ian; Wolf, Bettina

    2015-05-13

    In this research a microstructure approach to reduce sodium levels in emulsion based foods is presented. If successful, this strategy will enable reduction of sodium without affecting consumer satisfaction with regard to salty taste. The microstructure approach comprised of entrapment of sodium in the internal aqueous phase of water-in-oil-in-water emulsions. These were designed to destabilise during oral processing when in contact with the salivary enzyme amylase in combination with the mechanical manipulation of the emulsion between the tongue and palate. Oral destabilisation was achieved through breakdown of the emulsion that was stabilised with a commercially modified octenyl succinic anhydride (OSA)-starch. Microstructure breakdown and salt release was evaluated utilising in vitro, in vivo and sensory methods. For control emulsions, stabilised with orally inert proteins, no loss of structure and no release of sodium from the internal aqueous phase was found. The OSA-starch microstructure breakdown took the initial form of oil droplet coalescence. It is hypothesised that during this coalescence process sodium from the internalised aqueous phase is partially released and is therefore available for perception. Indeed, programmed emulsions showed an enhancement in saltiness perception; a 23.7% reduction in sodium could be achieved without compromise in salty taste (p < 0.05; 120 consumers). This study shows a promising new approach for sodium reduction in liquid and semi-liquid emulsion based foods. PMID:25865459

  7. Responsiveness of emulsions stabilized by lactoferrin nano-particles to simulated intestinal conditions.

    PubMed

    Meshulam, Dafna; Lesmes, Uri

    2014-01-01

    There is an upsurge of interest in the use of nano-particles to fabricate emulsions and modulate their functionality, with particular emphasis on modulating emulsion digestive fate. Food grade nano-particles formed through controlled processing and electrostatic biopolymer interactions are yet to be systematically studied for their ability to stabilize emulsions and modulate emulsion digestibility. This study focused on the responsiveness of emulsions stabilized by lactoferrin (LF) nano-particles (NPs) and dietary fibers to key digestive parameters. Compared to native LF, LF-NPs comprised emulsion exhibited elevated creaming rates as evident from accelerated stability tests performed by analytical centrifugation. The electrostatic deposition of alginate or carrageenan onto the LF-NPs significantly improved the stability of the corresponding emulsions. Further, the use of various nano-particles showed to have both beneficial and deleterious effects on emulsion responsiveness to pH (2.0 < pH < 10.0), CaCl2 (0-40 mM) and bile (0-25 mg mL(-1)). Simulated pH-stat lipolysis experiments show that the use of LF or LF-NPs had no marked effect on lipolysis. Intriguingly, the use of LF-NPs and alginate reduced emulsion lipolysis by 14% while the use of LF-NPs and carrageenan increased lipolysis by 10%. Microscopy images as well as droplet characterization in terms of size and charge indicate that the altered emulsion responsiveness may be due to physical differences in emulsion properties (e.g. droplet size) and overall organization during digestion (e.g. aggregation vs. coalescence). Overall, this study's insights could prospectively be used to harness protein nano-particles to tweak emulsion behavior during digestion. PMID:24247725

  8. Optimization of the canola oil based vitamin E nanoemulsions stabilized by food grade mixed surfactants using response surface methodology.

    PubMed

    Mehmood, Tahir

    2015-09-15

    The objective of the present study was to prepare canola oil based vitamin E nanoemulsions by using food grade mixed surfactants (Tween:80 and lecithin; 3:1) to replace some concentration of nonionic surfactants (Tween 80) with natural surfactant (soya lecithin) and to optimize their preparation conditions. RBD (Refined, Bleached and Deodorized) canola oil and vitamin E acetate were used in water/vitamin E/oil/surfactant system due to their nutritional benefits and oxidative stability, respectively. Response surface methodology (RSM) was used to optimize the preparation conditions. The effects of homogenization pressure (75-155MPa), oil concentrations (4-12% w/w), surfactant concentrations (3-11% w/w) and vitamin E acetate contents (0.4-1.2% w/w) on the particle size and emulsion stability were studied. RSM analysis has shown that the experimental data could be fitted well into second-order polynomial model with the coefficient of determinations of 0.9464 and 0.9278 for particle size and emulsion stability, respectively. The optimum values of independent variables were 135MPa homogenization pressure, 6.18% oil contents, 6.39% surfactant concentration and 1% vitamin E acetate concentration. The optimized response values for particle size and emulsion stability were 150.10nm and 0.338, respectively. Whereas, the experimental values for particle size and nanoemulsion stability were 156.13±2.3nm and 0.328±0.015, respectively. PMID:25863602

  9. Preparation of transparent polystyrene nano-latexes by an UV-induced routine emulsion polymerization

    Microsoft Academic Search

    Xuefeng Hu; Jieyu Zhang; Wantai Yang

    2009-01-01

    Transparent polystyrene (PS) latexes were prepared by photo-polymerization of a routine styrene (St) emulsion with a surfactant concentration of 0.4wt% and a monomer concentration of 10wt%, by using UV light as well as a hydrophilic photo-initiator. The entire polymerization could be performed within 1–2h and display a conversion higher than 90%. The particle sizes could be tuned in the range

  10. On-line light backscattering tracking of the transitional phase inversion of emulsions

    Microsoft Academic Search

    Aldo Pizzino; Marianne Catté; Elisabeth Van Hecke; Jean-Louis Salager; Jean-Marie Aubry

    2009-01-01

    A surfactant\\/oil\\/water system (Brij 30\\/decane\\/brine) is stirred while continuously changing the temperature in order to induce the swap of the emulsion morphology from O\\/W to W\\/O or vice versa. The transitional phase inversion is detected by monitoring both the electrical conductivity and the light backscattering with a Turbiscan (on line) equipment. The optical technique pinpoints the inversion and exhibits several

  11. Selective Separation of Gallium from Acidic Leach Solutions by Emulsion Liquid Membranes

    Microsoft Academic Search

    R. A. Kumbasar; O. Tutkun

    2006-01-01

    The separation and concentration of gallium from acidic leach solutions, containing various other ions such as iron, cobalt, nickel, zinc, cadmium, lead, copper, and aluminium, by an emulsion liquid membrane (ELM) technique using tributyl phosphate (TBP) as carrier has been presented. Liquid membrane consists of a diluent, a surfactant (ECA 4360J), and an extractant (TBP), and 0.1 M HCl or 0.1 M

  12. Microencapsulation of octadecane as a phase-change material by interfacial polymerization in an emulsion system

    Microsoft Academic Search

    Jeong-Sook Cho; Aehwa Kwon; Chang-Gi Cho

    2002-01-01

    Microcapsules containing phase-change material for thermal adaptable fiber application were synthesized and characterized.\\u000a The microcapsules of about 1 ?m in diameter were prepared using an interfacial polycondensation method with toluene-2,4-diisocyanate\\u000a (TDI) and diethylenetriamine (DETA) as monomers in an emulsion system. Octadecane was used as a phase-change material and\\u000a NP-10 which is nonionic surfactant, was used as an emulsifier. To investigate

  13. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2004-01-01

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

  14. Use of surfactants for the remediation of contaminated soils: a review.

    PubMed

    Mao, Xuhui; Jiang, Rui; Xiao, Wei; Yu, Jiaguo

    2015-03-21

    Due to the great harm caused by soil contamination, there is an increasing interest to apply surfactants to the remediation of a variety of contaminated soils worldwide. This review article summarizes the findings of recent literatures regarding remediation of contaminated soils/sites using surfactants as an enhancing agent. For the surfactant-based remedial technologies, the adsorption behaviors of surfactants onto soil, the solubilizing capability of surfactants, and the toxicity and biocompatibility of surfactants are important considerations. Surfactants can enhance desorption of pollutants from soil, and promote bioremediation of organics by increasing bioavailability of pollutants. The removal of heavy metals and radionuclides from soils involves the mechanisms of dissolution, surfactant-associated complexation, and ionic exchange. In addition to the conventional ionic and nonionic surfactants, gemini surfactants and biosurfactants are also applied to soil remediation due to their benign features like lower critical micelle concentration (CMC) values and better biocompatibility. Mixed surfactant systems and combined use of surfactants with other additives are often adopted to improve the overall performance of soil washing solution for decontamination. Worldwide the field studies and full-scale remediation using surfactant-based technologies are yet limited, however, the already known cases reveal the good prospect of applying surfactant-based technologies to soil remediation. PMID:25528485

  15. Comparative effects of different cosurfactants on sterile prednisolone acetate ocular submicron emulsions stability and release.

    PubMed

    Ibrahim, Shaimaa S; Awad, Gehanne A S; Geneidi, Ahmed; Mortada, Nahed D

    2009-03-01

    Pluronic F68 is a nonionic, thermogelling block copolymer showing a high dehydration resistance during autoclaving due to its high cloud point (>100 degrees C). Tween 80 (with cloud point of 72.5 degrees C), is a polyoxyethylene-based cosurfactant, susceptible to temperature because of a decrease in its solubility by temperature increase. This study was done to explore whether or not, when compared with Tween 80, Pluronic F68 could be used blindly as a suitable cosurfactant for the preparation of terminally sterilized ocular submicron emulsions containing a lipid soluble drug, prednisolone acetate (PA). Various oils of variable viscosities were also tried. The results proved that no prediction can be made based on previously known physico-chemical properties alone and that emulsion stability depends on the contribution of the various emulsion components including: oil, surfactant and cosurfactant, in addition to the drug properties. PMID:19157802

  16. Synthesis and characterization of ?-CD-coated polystyrene microspheres by ?-ray radiation emulsion polymerization.

    PubMed

    Xu, Dezhi; Wang, Mozhen; Ge, Xuewu; Lam, Michael Hon-Wah

    2012-11-23

    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

  17. Stable emulsions formed by self-assembly of interfacial networks of dipeptide derivatives.

    PubMed

    Bai, Shuo; Pappas, Charalampos; Debnath, Sisir; Frederix, Pim W J M; Leckie, Joy; Fleming, Scott; Ulijn, Rein V

    2014-07-22

    We demonstrate the use of dipeptide amphiphiles that, by hand shaking of a biphasic solvent system for a few seconds, form emulsions that remain stable for months through the formation of nanofibrous networks at the organic/aqueous interface. Unlike absorption of traditional surfactants, the interfacial networks form by self-assembly through ?-stacking interactions and hydrogen bonding. Altering the dipeptide sequence has a dramatic effect on the properties of the emulsions formed, illustrating the possibility of tuning emulsion properties by chemical design. The systems provide superior long-term stability toward temperature and salts compared to with sodium dodecyl sulfate (SDS) and can be enzymatically disassembled causing on-demand demulsification under mild conditions. The interfacial networks facilitate highly tunable and stable encapsulation and compartmentalization with potential applications in cosmetics, therapeutics, and food industry. PMID:24896538

  18. Effect of some petroleum sulfonate surfactants on the apparent water solubility of organic compounds

    SciTech Connect

    Kile, D.E.; Chiou, C.T. (Geological Survey, Denver, CO (USA)); Helburn, R.S. (Colorado School of Mines, Golden (USA))

    1990-02-01

    Water solubility enhancements of 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT) and 1,2,3-trichlorobenzene (TCB) by some commercial petroleum sulfonates (Petronate L, Petronate HL, and Pyronate 40) were studied at room temperature. Unlike conventional surfactants, the petroleum sulfonate surfactants are mixtures of sulfonated hydrocarbons and free mineral oils, which form stable emulsions in water and thus behave much like a bulk organic phase in concentrating organic solutes. The extent of solubility enhancement is linearly proportional to the concentration of the petroleum sulfonate-oil (PSO) emulsion, in contrast with the effect of a conventional surfactant in which a sharp inflection occurs in the vicinity of the critical micelle concentration (CMC). The enhancement effect of the PSO surfactant is 1.5-3 orders of magnitude greater than that of ordinary surfactant monomers below the CMC. The partition coefficient of the solute between the emulsified PSO phase and water (K{sub em}) is closely related to the nonpolar content of the PSO surfactant; the normalized K{sub em} values are about the same order of magnitude as the solvent (octanol)-water partition coefficients of the solutes.

  19. An emulsion polymerization process for soluble and electrically conductive polyaniline

    SciTech Connect

    Kinlen, P.J.; Ding, Y.; Graham, C.R.; Liu, J.; Remsen, E.E.

    1998-07-01

    A new emulsion process has been developed for the direct synthesis of the emeraldine salt of polyaniline (PANI) that is soluble in organic solvents. The process entails forming an emulsion composed of water, a water soluble organic solvent (e.g., 2-butoxyethanol), a water insoluble organic acid (e.g., dinonylnaphthalene sulfonic acid) and aniline. Aniline is protonated by the organic acid to form a salt which partitions into the organic phase. As oxidant (ammonium peroxydisulfate) is added, PANI salt forms in the organic phase and remains soluble. As the reaction proceeds, the reaction mixture changes from an emulsion to a two phase system, the soluble PANI remaining in the organic phase. With dinonylnaphthalene sulfonic acid (DNNSA) as the organic acid, the resulting product is truly soluble in organic solvents such as xylene and toluene (not a dispersion), of high molecular weight (M{sub w} > 22,000), film forming and miscible with many polymers such as polyurethanes, epoxies and phenoxy resins. As cast, the polyaniline film is only moderately conductive, (10{sup {minus}5} S/cm), however treatment of the film with surfactants such as benzyltriethylammonium chloride (BTEAC) or low molecular weight alcohols and ketones such as methanol and acetone increases the conductivity 2--3 orders of magnitude.

  20. Separation of aniline from aqueous solutions using emulsion liquid membranes.

    PubMed

    Devulapalli, R; Jones, F

    1999-12-31

    An emulsion liquid membrane process is developed to separate aniline from dilute aqueous solution. Aniline (amino-benzene) is a carcinogenic chemical common in industry and industrial wastewater. Due to aniline's high boiling point (183 degrees C) and low concentration in wastewater, more traditional methods of separation such as distillation are very energy intensive. This emulsion process is offered as a low energy alternative. All separations occur in a Rushton stirred tank. The membrane phase consists of kerosene and the surfactant sorbitan monooleate (span 80). Hydrogen chloride solution is the internal phase. This study also examines the effects of HCl concentration, aniline concentration, and the amount of emulsion on separation. Up to 99.5% of the aniline is removed from solutions containing 5000 ppm in as little as 4 min depending on process conditions. Leakage is minimal and swelling is only about 3% after 5 min of processing. Approximately 98% of the membrane phase (both kerosene and span 80) is successfully recovered and recycled by using heat and/or adding 2-propanol for demulsification. PMID:10631354

  1. 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)

    Javadian, Soheila; Yousefi, Ali; Neshati, Jaber

    2013-11-01

    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.

  2. Phytosterol colloidal particles as Pickering stabilizers for emulsions.

    PubMed

    Liu, Fu; Tang, Chuan-He

    2014-06-01

    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

  3. Breaking oil-in-water emulsions stabilized by yeast.

    PubMed

    Furtado, Guilherme F; Picone, Carolina S F; Cuellar, Maria C; Cunha, Rosiane L

    2015-04-01

    Several biotechnological processes can show an undesirable formation of emulsions making difficult phase separation and product recovery. The breakup of oil-in-water emulsions stabilized by yeast was studied using different physical and chemical methods. These emulsions were composed by deionized water, hexadecane and commercial yeast (Saccharomyces cerevisiae). The stability of the emulsions was evaluated varying the yeast concentration from 7.47 to 22.11% (w/w) and the phases obtained after gravity separation were evaluated on chemical composition, droplet size distribution, rheological behavior and optical microscopy. The cream phase showed kinetic stability attributed to mechanisms as electrostatic repulsion between the droplets, a possible Pickering-type stabilization and the viscoelastic properties of the concentrated emulsion. Oil recovery from cream phase was performed using gravity separation, centrifugation, heating and addition of demulsifier agents (alcohols and magnetic nanoparticles). Long centrifugation time and high centrifugal forces (2 h/150,000×g) were necessary to obtain a complete oil recovery. The heat treatment (60°C) was not enough to promote a satisfactory oil separation. Addition of alcohols followed by centrifugation enhanced oil recovery: butanol addition allowed almost complete phase separation of the emulsion while ethanol addition resulted in 84% of oil recovery. Implementation of this method, however, would require additional steps for solvent separation. Addition of charged magnetic nanoparticles was effective by interacting electrostatically with the interface, resulting in emulsion destabilization under a magnetic field. This method reached almost 96% of oil recovery and it was potentially advantageous since no additional steps might be necessary for further purifying the recovered oil. PMID:25791419

  4. Water Vapor Sorption and Diffusion in Secondary Dispersion Barrier Coatings: A Critical Comparison with Emulsion Polymers.

    PubMed

    Liu, Yang; Soer, Willem-Jan; Scheerder, Jürgen; Satgurunathan, Guru; Keddie, Joseph L

    2015-06-10

    The conventional method for synthesizing waterborne polymer colloids is emulsion polymerization using surfactants. An emerging method is the use of secondary dispersions (SD) of polymers in water, which avoids the addition of any surfactant. Although there are numerous studies of the water barrier properties (sorption, diffusion, and permeability) of waterborne emulsion (Em) polymer coatings, the properties of SD coatings, in comparison, have not been thoroughly investigated. Here, dynamic water vapor sorption analysis is used to compare the equilibrium sorption isotherms of the two forms of styrene-acrylate copolymers (Em and SD) with the same monomer composition. From an analysis of the kinetics of vapor sorption, the diffusion coefficient of water in the polymer coatings is determined. The combined effects of particle boundaries and surfactant addition were investigated through a comparison of the properties of SD and Em coatings to those of (1) solvent-cast polymer coatings (of the same monomer composition), (2) Em polymers that underwent dialysis to partially remove the water-soluble species, and (3) SD polymers with added surfactants. The results reveal that both the particle boundaries and the surfactants increase vapor sorption. The diffusion coefficients of water are comparable in magnitude in all of the polymer systems but are inversely related to water activity because of molecular clustering. Compared to all of the other waterborne polymer systems, the SD barrier coatings show the lowest equilibrium vapor sorption and permeability coefficients at high relative humidities as well as the lowest water diffusion coefficient at low humidities. These barrier properties make SD coatings an attractive alternative to conventional emulsion polymer coatings. PMID:25985183

  5. Study of an Amphoteric Surfactant in a Soil Decontamination Process Using ANS Enhanced Fluorescence: Micellar Behavior and Dosing in Synthetic and Soil Solutions

    Microsoft Academic Search

    Pascal Castellazzi; Guy Mercier; Jean-François Blais

    Cocamidopropyl hydroxysultaine (CAS) has been used in a pilot plant study as a biodegradable surfactant for the extraction\\u000a of polycyclic aromatic hydrocarbons (PAHs) and lead (Pb) from contaminated soils. The soil treatment has been done in flotation\\u000a cells with a concentration of 0.20 g?CAS L?1 in saline conditions (3 M NaCl) and using a pulp density of 20% (w\\/w). The process integrates

  6. Phase volume effects in the sub- and super-CMC partitioning of nonionic surfactant mixtures between water and immiscible organic liquids

    Microsoft Academic Search

    Tohren C. G. Kibbey; Lixia Chen

    2008-01-01

    It is a widely held misconception that surfactant phenomena involving adsorption or partitioning between phases plateau at aqueous concentrations beyond the surfactant critical micelle concentration (CMC). While this is generally true for single-component surfactants, it has been recognized for some time that mixed surfactants can deviate from this behavior, in some cases to dramatic extents. This paper examines the influence

  7. Surfactants and the environment

    Microsoft Academic Search

    Larry N. Britton

    1998-01-01

    A large body of information on the environmental attributes of commercial surfactants has been generated in response to concerns\\u000a about the environmental fate and effects of these high-volume chemicals. This review examines the scientific disciplines involved\\u000a in evaluating the environmental acceptability of surfactants and highlights the current issues.

  8. SURFACTANTS AND SUBSURFACE REMEDIATION

    EPA Science Inventory

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

  9. 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...

  10. Experimental Evaluation of Surfactant Application to Improve Oil Recovery

    E-print Network

    Liu, Zhijun

    2011-09-16

    The objective of this research was to identify high performance surfactant formulations and design efficient core floods for a limestone reservoir with high salinity formation brine. Microemulsion phase behavior experiments ...

  11. Kenaf as a deep-bed filter medium to remove oil from oil-in-water emulsions

    SciTech Connect

    Varghese, B.K.; Cleveland, T.G. [Univ. of Houston, TX (United States)

    1998-10-01

    This study investigated the feasibility of deep-bed filtration using kenaf (agricultural fiber) media for the removal of oil from oil-in-waste emulsions. Continuous flow, constant pressure filtrations were conducted using surfactant stabilized emulsions. Removal of oil and grease varied from 70 to 95% for 500 mg/L oil-in-water emulsion stabilized by surfactants. Oil removal was better for larger oil drops, finer media particles, higher filtration pressure, lower pH, cationic surfactant, and deeper media. Moisture contents and heating values of the spent media were determined. Moisture content decreased with increasing filtration pressure and decreasing particle size of the media. Heating values of the spent media increased with the volume of emulsion filtered. Heating values were high enough to produce surplus energy after accounting for the energy required for driving out the moisture. The results indicated that it may be possible to dispose of the spent medium by combustion without further drying and extract net energy in the process.

  12. The effect of stabilizer on the mechanical response of double-emulsion-templated polymersomes.

    PubMed

    Jang, Woo-Sik; Park, Seung Chul; Kim, Miju; Doh, Junsang; Lee, Daeyeon; Hammer, Daniel A

    2015-02-01

    Recent studies have shown that polymersomes templated by microfluidic double-emulsion possess several advantages such as high monodispersity and encapsulation efficiency compared with those generated based on thin-film rehydration and electroformation. Stabilizers, including bovine serum albumin (BSA) and polyvinyl alcohol (PVA), have been used to enhance the formation and stability of double emulsions that are used as templates for the generation of polymersomes. In this work, the effect of stabilizers on the mechanical response of double-emulsion-templated polymersomes using micropipette aspiration is investigated. It is demonstrated that the existence of stabilizers results in the inelastic response in poly-mersomes in the early stage of solvent removal. However, aged polymersomes that have little residual solvent show elastic behavior. Polymersomes prepared from PVA-stabilized double emulsions have noticeably lower area expansion moduli than polymersomes prepared from stabilizer-free and BSA-stabilized double emulsions, suggesting that PVA is incorporated in the bilayer membrane of polymersomes. PMID:25515004

  13. Emulsifying properties and surface behavior of native and denatured whey soy proteins in comparison with other proteins. Creaming stability of oil-in-water emulsions

    Microsoft Academic Search

    Gonzalo G. Palazolo; Delia A. Sorgentini; Jorge R. Wagner

    2004-01-01

    In this work a comparative study of emulsifying and surface behaviors of native whey soy proteins (NWSP) and denatured whey\\u000a soy proteins (DWSP) with those of native soy isolates, denatured soy isolates (DSI), and sodium caseinate was done. These\\u000a samples showed different molecular mass distributions in gel filtration profiles. Dissociation and soluble high-M.W. species\\u000a in DWSP and DSI were observed.

  14. Thermocapillary Motion in an Emulsion

    NASA Technical Reports Server (NTRS)

    Pukhnachov, Vladislav V.; Voinov, Oleg V.

    1996-01-01

    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.

  15. Rheology of high internal phase emulsions.

    PubMed

    Welch, Cynthia F; Rose, Gene D; Malotky, David; Eckersley, Sarah T

    2006-02-14

    The mechanical dispersion technology used in this study employs rotor-stator mixers that produce water-continuous high internal phase emulsions (HIPEs) with narrow drop size distributions and small drop sizes, even when the internal phase (oil) viscosity is quite high. Analysis of these HIPEs reveals trends that are consistent with formation by a capillary instability mechanism in which a shear deformation produces highly elongated drops that rupture to form uniform, small droplets. In the search for a predictive tool to aid in the manufacture and use of HIPEs, rheology data for these shear-thinning HIPEs have been compared to data for models in the literature. Existing models do not correctly account for the effect of a high internal phase viscosity on the rheological properties of the HIPE. Another shortcoming is failure to correctly address the shear-thinning exponent. Whereas internal phase viscosity does not seem to affect the shear-thinning exponent, the surfactant apparently plays an important role, possibly through its modification of the interfacial tension and continuous phase rheology. PMID:16460072

  16. Non-ionic surfactants do not consistently improve the enzymatic hydrolysis of pure cellulose.

    PubMed

    Zhou, Yan; Chen, Hongmei; Qi, Feng; Zhao, Xuebing; Liu, Dehua

    2015-04-01

    Non-ionic surfactants have been frequently reported to improve the enzymatic hydrolysis of pretreated lignocellulosic biomass and pure cellulose. However, how the hydrolysis condition, substrate structure and cellulase formulation affect the beneficial action of surfactants has not been well elucidated. In this work, it was found that the enzymatic hydrolysis of pure cellulose was not consistently improved by surfactants. Contrarily, high surfactant concentration, e.g. 5 g/L, which greatly improved the hydrolysis of dilute acid pretreated substrates, actually showed notable inhibition to pure cellulose conversion in the late phase of hydrolysis. Under an optimal hydrolysis condition, the improvement by surfactant was limited, but under harsh conditions surfactant indeed could enhance cellulose conversion. It was proposed that non-ionic surfactants could interact with substrates and cellulases to impact the adsorption behaviors of cellulases. Therefore, the beneficial action of surfactants on pure cellulose hydrolysis is influenced by hydrolysis condition, cellulose structural features and cellulase formulation. PMID:25689307

  17. Overview of Surfactant Replacement Trials

    Microsoft Academic Search

    Gautham K Suresh; Roger F Soll

    2005-01-01

    Clinical trials have evaluated the overall efficacy of surfactant therapy, as well as the relative efficacy of different surfactant preparations, the optimal timing of administration and the optimal dosage. Surfactant therapy leads to significant clinical improvement in infants at risk for, or having, respiratory distress syndrome (RDS). Clinical trials that compared the effects of synthetic or animal-derived surfactant preparations to

  18. Adsorption at the biocompatible ?-pinene-water interface and emulsifying properties of two eco-friendly surfactants.

    PubMed

    Trujillo-Cayado, Luis Alfonso; Ramírez, Pablo; Alfaro, María Carmen; Ruíz, Manuela; Muñoz, José

    2014-10-01

    In this contribution, we provide an accurate characterization at the ?-pinene/water interface of two commercial polyoxytheylene glycerol ester surfactants which differ in the number of ethylene oxide (EO) groups, comprising a systematic analysis of interfacial pressure isotherms, dynamic curves, interfacial rheology and emulsifying properties. Polyoxyethylene glycerol esters derived from cocoa oil are non-ionic surfactants obtained from a renewable source which fulfill the environmental and toxicological requirements to be used as eco-friendly emulsifying agents. ?-Pinene is a renewable biosolvent completely insoluble in water, which could find numerous applications. Interfacial rheology and equilibrium interfacial pressure data fitted a rigorous reorientation model that assumes that the surfactant molecules, when adsorbed at the interface, can acquire two orientations. The surfactant with the highest number of EO groups (Levenol C201) turned out to be more surface active at the ?-pinene/water interface. In addition, the surfactant with the lowest number of EO groups (Levenol H&B) is solubilized into the adjacent oil phase. Slightly concentrated ?-pinene emulsions were obtained using both surfactants. Nevertheless, more stable ?-pinene emulsions with smaller droplet sizes and lower polidispersity were obtained when Levenol C201 was used as emulsifier instead of Levenol H&B. The systematic characterization presented in this work provides important new findings on the interfacial and emulsifying properties of polyoxytheylene glycerol ester surfactants, which can be applied in the rational development of new biocompatible products. PMID:25129697

  19. Characterization, biodistribution and targeting evaluation of breviscapine lipid emulsions following intravenous injection in mice.

    PubMed

    Xiong, Fei; Wang, Hao; Chen, Yue-Jian; Geng, Kun-Kun; Gu, Ning; Zhu, Jia-Bi

    2011-02-01

    Breviscapine lipid emulsions were prepared by a high speed dispersion-homogenization method with optimal formulation and technological method. The proportion of liposomes in breviscapine lipid emulsions, an important character for determining the behavior of drug in vivo belongs to which carriers, was less than 5%. Loading breviscapine into lipid emulsions did increase the breviscapine concentrations in plasma, retarded the clearance, and exhibited the properties of sustained-release concluded by pharmacokinetic parameters: after bolus administration, the elimination phase (t(1/2(?))?=?99.535) of lipid emulsions was 5.4-times longer than that of Injectio Breviscapine. The AUC(0??) (14.453-times), k(10) (0.047-times), Cl(s) (0.147-times), and MRT(0??) (17.766-times) values also confirmed this trend. The amount of drug in every tissue increased at different levels after intravenous administration of breviscapine lipid emulsions compared with Injectio Breviscapine. The relative exposure value of breviscapine lipid emulsions for plasma and lungs were 29.59 and 5.81, respectively, indicating that the exposure of breviscapine to plasma and lungs was significantly increased by entrapment in lipid emulsions. Other targeting evaluation indexes also proved the superiority of lipid emulsions carrier to deliver drug to the targeting region of vascular and lung diseases therapy. PMID:21028951

  20. A practicable process for phenol removal with liquid surfactant membrane permeation column

    SciTech Connect

    Kataoka, Takeshi; Osaki, Katsuhiko; Nishiki, Tadaaki [Osaka Prefecture Univ. (Japan)] [and others

    1997-05-01

    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.

  1. Surfactants in the environment.

    PubMed

    Ivankovi?, Tomislav; Hrenovi?, Jasna

    2010-03-01

    Surfactants are a diverse group of chemicals that are best known for their wide use in detergents and other cleaning products. After use, residual surfactants are discharged into sewage systems or directly into surface waters, and most of them end up dispersed in different environmental compartments such as soil, water or sediment. The toxic effects of surfactants on various aquatic organisms are well known. In general, surfactants are present in the environment at levels below toxicity and in Croatia below the national limit. Most surfactants are readily biodegradable and their amount is greatly reduced with secondary treatment in wastewater treatment plants. The highest concern is the release of untreated wastewater or wastewater that has undergone primary treatment alone. The discharge of wastewater polluted with massive quantities of surfactants could have serious effects on the ecosystem. Future studies of surfactant toxicities and biodegradation are necessary to withdraw highly toxic and non-biodegradable compounds from commercial use and replace them with more environmentally friendly ones. PMID:20338873

  2. Self-Assembly of Nanoparticle Surfactants

    NASA Astrophysics Data System (ADS)

    Lombardo, Michael T.

    Self-assembly utilizes non-covalent forces to organize smaller building blocks into larger, organized structures. Nanoparticles are one type of building block and have gained interest recently due to their unique optical and electrical properties which have proved useful in fields such as energy, catalysis, and advanced materials. There are several techniques currently used to self-assemble nanoparticles, each with its own set of benefits and drawbacks. Here, we address the limited number of techniques in non-polar solvents by introducing a method utilizing amphiphilic gold nanoparticles. Grafted polymer chains provide steric stabilization while small hydrophilic molecules induce assembly through short range attractive forces. The properties of these self-assembled structures are found to be dependent on the polymer and small molecules surface concentrations and chemistries. These particles act as nanoparticle surfactants and can effectively stabilize oil-water interfaces, such as in an emulsion. In addition to the work in organic solvent, similar amphiphilic particles in aqueous media are shown to effectively stabilize oil-in-water emulsions that show promise as photoacoustic/ultrasound theranostic agents.

  3. Flow of oil-in-water emulsions through orifice and venturi meters

    SciTech Connect

    Pal, R. (Univ. of Waterloo (Canada). Department of Chemical Engineering)

    1993-06-01

    The applicability of conventional orifice and venturi meters to monitor the flow rate of oil/water emulsions was investigated. The discharge coefficients were determined for various unstable and surfactant-stabilized oil-in-water emulsions using a single orifice and a single venturi. The oil concentration was varied over a wide range of 0-84.32 vol %. The metering results indicate that orifice and venturi meters are feasible flow measuring devices for emulsions. The usual calibration curves of discharge coefficient versus Reynolds number (obtained from single-phase Newtonian fluids) are valid for the stable emulsions, both Newtonian and non-Newtonian. In the latter case, one needs to use the generalized Reynolds number instead of the conventional one. The orifice and venturi discharge coefficients for the unstable emulsions tend to deviate from the single-phase curves at low values of Reynolds number although the agreement is good at high Reynolds numbers. Based on the experimental data, empirical expressions for the orifice and venturi discharge coefficients are given.

  4. Starch nanocrystal stabilized Pickering emulsion polymerization for nanocomposites with improved performance.

    PubMed

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

    2014-06-11

    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

  5. Study of emulsion stabilization by graft copolymers using the optical analyzer Turbiscan.

    PubMed

    Lemarchand, Caroline; Couvreur, Patrick; Vauthier, Christine; Costantini, Dominique; Gref, Ruxandra

    2003-03-18

    Oil-in-water nanoemulsions were prepared using a series of synthetic graft copolymers with a backbone of dextran (DEX) and a number of side chains of poly-epsilon-caprolactone (PCL). In this paper, we focus on the o/w emulsion stabilizing abilities of these novel PCL-DEX copolymers, using a recently developed optical analyzer (Turbiscan). The main advantage of Turbiscan is to detect the destabilization phenomena in non-diluted emulsion, much earlier than the naked eye's operator, especially in the case of an opaque and concentrated system. This study shows that PCL-DEX copolymers successfully stabilized ethyl acetate-in-water emulsions, even in the absence of additional surfactants, whereas they were not efficient in stabilizing methylene chloride-in-water emulsions which coalesced fast and irreversibly. The ethyl acetate-in-water emulsion stabilizing ability of PCL-DEX seemed to be related to the localization of their blocks with regard to the oil-water interface. PMID:12615414

  6. Surfactant-mediated modulation of hydrophobic interactions in associative polymer solutions containing cyclodextrin.

    PubMed

    Talwar, Sachin; Harding, Jonathon; Oleson, Keith R; Khan, Saad A

    2009-01-20

    The ability of nonionic surfactants to modulate the rheological characteristics of comblike hydrophobically modified associative polymer solutions containing cyclodextrin (CD) is examined. Addition of either alpha- or beta-CD to these polymers results in a marked decrease in solution viscosity and viscoelastic properties because of the encapsulation of the polymer hydrophobes by CD. Nonionic surfactants, introduced to such a system, alter the hydrophobic interactions by competing with the polymer hydrophobes for complexation with the CDs. In this regard, nonylphenol ethoxylates (NPe) with different ethylene oxide chain lengths, which determine the hydrophilic-lipophilic balance (HLB) of the surfactant, are used. Our results reveal that the extent and rate of recovery of zero shear viscosity as well as dynamic moduli are strongly influenced by the type of CD (alpha versus beta) as well as the HLB of the surfactant. For polymer solutions containing alpha-CD, recovery is observed solely in the presence of a low-HLB surfactant (NP6 and NP8). Additionally, in the case of NP6, the viscosity increases monotonically above the original hydrophobically modified alkali-soluble emulsion viscosity with surfactant addition, whereas for that of a higher HLB surfactant (NP15), the viscosity shows no appreciable change. In the case of beta-CD, on the other hand, a complete recovery as well as further enhancement of rheological properties is achieved using the above surfactants. However, the trends of viscosity modulation are dissimilar for different surfactants as we witness a monotonous increase in the case of NP6 while a maximum in viscosity is observed in the presence of NP8 and NP15. The contrasting observations can be explained in terms of varying affinities of alpha- and beta-CDs to bind with NP surfactants and the existence of different micellar structures in solution as governed by surfactant HLB. These results are further confirmed by UV/vis spectroscopy and cloud point measurements. PMID:19072321

  7. Self-Assembly of Gemini Surfactants

    NASA Astrophysics Data System (ADS)

    Yethiraj, Arun; Mondal, Jagannath; Mahanthappa, Mahesh

    2013-03-01

    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.

  8. Solubility and aggregation of charged surfactants in ionic liquids.

    PubMed

    Chen, Lang G; Bermudez, Harry

    2012-01-17

    Room-temperature ionic liquids (ILs) exhibit a unique set of properties, leading to opportunities for numerous applications. To obtain a better understanding of IL interfaces at a molecular level, we combined charged surfactants with ILs and studied their interfacial behavior. The critical micelle concentration (cmc) of each surfactant-IL pair was determined from both solubility phase diagrams and isotherms. Because the cmc is equivalent to the solubility at the Krafft temperature, a connection between the solubility of the surfactant and the physical properties of the underlying ionic liquid was established. Interfacial energy was found to be the major factor affecting the surfactant aggregation process, although its magnitude depends strongly on the IL structure. The results here give insight into explaining the nature of self-assembly of surfactants at IL interfaces and the interaction between solutes and IL solvents. PMID:22168452

  9. Aqueous Gemini Surfactant Self-Assembly into Complex Lyotropic Phases

    NASA Astrophysics Data System (ADS)

    Mahanthappa, Mahesh; Sorenson, Gregory

    2012-02-01

    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.

  10. Effect of salts on formation and stability of vitamin E-enriched mini-emulsions produced by spontaneous emulsification.

    PubMed

    Saberi, Amir Hossein; Fang, Yuan; McClements, David Julian

    2014-11-19

    Emulsion-based delivery systems are being utilized to incorporate lipophilic bioactive components into various food, personal care, and pharmaceutical products. This study examined the influence of inorganic salts (NaCl and CaCl2) on the formation, stability, and properties of vitamin E-enriched emulsions prepared by spontaneous emulsification. These emulsions were simply formed by titration of a mixture of vitamin E acetate (VE), carrier oil (MCT), and nonionic surfactant (Tween 80) into an aqueous salt solution with continuous stirring. Salt type and concentration (0-1 N NaCl or 0-0.5 N CaCl2) did not have a significant influence on the initial droplet size of the emulsions. On the other hand, the isothermal and thermal stabilities of the emulsions depended strongly on salt levels. The cloud point of the emulsions decreased with increasing salt concentration, which was attributed to accelerated droplet coalescence in the presence of salts. Dilution (2-6 times) of the emulsions with water appreciably improved their thermal stability by increasing their cloud point, which was mainly attributed to the decrease in aqueous phase salt levels. The isothermal storage stability of the emulsions also depended on salt concentration; however, increasing the salt concentration decreased the rate of droplet growth, which was the opposite of its effect on thermal stability. Potential physicochemical mechanisms for these effects are discussed in terms of the influence of salt ions on van der Waals and electrostatic interactions. This study provides important information about the effect of inorganic salts on the formation and stability of vitamin E emulsions suitable for use in food, personal care, and pharmaceutical products. PMID:25343750

  11. Impact of formulation and particle size on stability and immunogenicity of oil-in-water emulsion adjuvants.

    PubMed

    Iyer, Vidyashankara; Cayatte, Corinne; Guzman, Bernardo; Schneider-Ohrum, Kirsten; Matuszak, Ryan; Snell, Angie; Rajani, Gaurav Manohar; McCarthy, Michael P; Muralidhara, Bilikallahalli

    2015-07-01

    Oil-in-water emulsions have gained consideration as vaccine adjuvants in recent years due to their ability to elicit a differentiated immunogenic response compared to traditional aluminum salt adjuvants. Squalene, a cholesterol precursor, is a natural product with immunostimulatory properties, making it an ideal candidate for such oil-in-water emulsions. Particle size is a key parameter of these emulsions and its relationship to stability and adjuvanticity has not been extensively studied. This study evaluates the effect of particle size on the stability and immunogenicity of squalene emulsions. We investigated the effect of formulation parameters such as surfactant concentration on particle size, resulting in particles with average diameter of 80 nm, 100 nm, 150 nm, 200 nm, or 250 nm. Emulsions were exposed to shear and temperature stresses, and stability parameters such as pH, osmolarity, size, and in-depth visual appearance were monitored over time. In addition, adjuvanticity of different particle size was assessed in a mouse model using Respiratory Syncytial Virus Fusion protein (RSV-F) as a model antigen. Temperature dependent phase separation appeared to be the most common route of degradation occurring in the higher particle sizes emulsions. The emulsions below 150 nm size maintained stability at either 5°C or 25°C, and the 80 nm diameter ones showed no measurable changes in size even after one month at 40°C. In vivo studies using the emulsions as an adjuvant with RSV F antigen revealed that superior immunogenicity could be achieved with the 80 nm particle size emulsion. PMID:26090563

  12. Waterflooding employing amphoteric surfactants

    SciTech Connect

    Stournas, S.

    1980-08-05

    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.

  13. Surfactant on a Thin Liquid Layer: Outward Spreading

    NASA Astrophysics Data System (ADS)

    Swanson, Ellen; Strickland, Stephen; Shearer, Michael; Daniels, Karen

    2013-11-01

    The spreading of insoluble surfactant molecules on a thin liquid layer can be modeled by a coupled system of two fourth order partial differential equations. The equations for the surfactant concentration and the height of the liquid layer are derived from the Stokes equations using the lubrication approximation, and have been accepted as an accurate prediction of the spreading behavior for over two decades. In experiments, we measure the surfactant concentration profile through fluorescence imaging of tagged lipids, while simultaneously measuring the height profile with laser profilometry. We compare the outward spreading observed in the experiment to that predicted by the numerical simulations of the model, and find inconsistencies for initial surfactant distributions both above and below the critical monolayer concentration. Similar inconsistencies are also found when the surfactant is spreading inward; these are described in the companion talk that follows. The spreading of insoluble surfactant molecules on a thin liquid layer can be modeled by a coupled system of two fourth order partial differential equations. The equations for the surfactant concentration and the height of the liquid layer are derived from the Stokes equations using the lubrication approximation, and have been accepted as an accurate prediction of the spreading behavior for over two decades. In experiments, we measure the surfactant concentration profile through fluorescence imaging of tagged lipids, while simultaneously measuring the height profile with laser profilometry. We compare the outward spreading observed in the experiment to that predicted by the numerical simulations of the model, and find inconsistencies for initial surfactant distributions both above and below the critical monolayer concentration. Similar inconsistencies are also found when the surfactant is spreading inward; these are described in the companion talk that follows. NSF DMS-0968258, RCSA 19788.

  14. Development and Assessment of Oil-in-Water Emulsions for Encapsulation of Reactive Iron Particles for Subsurface Delivery

    NASA Astrophysics Data System (ADS)

    Berge, N. D.; Taghavy, A.; Ramsburg, A.

    2007-12-01

    Reactive iron particles hold promise for use in the destruction of contaminants in the subsurface environment. Application of these nano- to submicron-scale particles, however, may be limited by poor subsurface transport and non-uniform distribution of the reactive material. Delivery issues are particularly important when evaluating the efficacy of iron-based technologies for treatment of dense non-aqueous phase liquid (DNAPL) source zones. Current approaches for the delivery of reactive iron particles within DNAPL source zones are hindered by particle agglomeration, flow bypassing, and presence of non-target reactions. Encapsulation of the reactive particles within an oil-in-water emulsion is a novel approach that may overcome these limitations. Development of kinetically-stable, iron-laden, oil-in-water emulsions commenced by identifying surfactant-based coatings to increase the stability of commercially-available iron particles within non-polar organic phases (e.g., soy oil). A phase inversion technique was employed to disperse approximately 10% wt of the iron-laden, organic phase within a continuous aqueous phase containing nonionic emulsifiers. Emulsions were designed to ensure emulsifier proportions yielded hydrophilic-lipophilic balances affiliated with oil-in-water emulsions. Micrographs of the oil-in-water emulsions suggest that the average diameter of the oil droplets is approximately one micrometer. The presence of iron within oil droplets was confirmed in the micrographs and supported by an absence of iron agglomeration within the continuous phase. Bulk characteristics of each emulsion (density and viscosity) were used in conjunction with interfacial tension measurements in total trapping number analyses to assess the propensity of these emulsions to mobilize an entrapped trichloroethene (TCE)-DNAPL. Results suggest that the emulsions described herein should not cause significant mobilization of entrapped TCE-DNAPL in fine-to-medium grain sandy media. Column experiments are being conducted to evaluate the transport of these emulsions through sandy media. Preliminary results from experiments with iron-free emulsions suggest conductivity reductions occurring during emulsion flushing are not the result of extensive pore-clogging but rather are due to viscosity changes (emulsion viscosities range from 2 to 10 cP). Current efforts are focused on assessing and comparing both transport and reaction of commercially available iron particles and iron-laden emulsions within sandy porous media.

  15. Effects of surfactants on the deformation of microfluidic drops

    NASA Astrophysics Data System (ADS)

    Cordero, Maria Luisa; Ulloa, Camilo

    2013-11-01

    A microfluidic analog of the four-roll-mill experiment is used to study the deformation and breakup of microfluidic drops. The behavior of water drops flowing in mineral oil is quantified as a function of the capillary number, Ca , which is based on the oil viscosity, drop radius, flow shear rate and equilibrium interfacial tension, both in the presence and absence of surfactants. In the absence of surfactants the deformation of the drops increases linearly with Ca . If surfactants are added to the carrier oil then, for the same value of Ca , drops deform less if the flow velocity is larger. Moreover, for a given drop size in the presence of surfactants, drops begin to split at a threshold shear rate but stop breaking if the shear rate is increased beyond a second threshold. These observations are explained by a decrease in the surfactant concentration at the surface of the drop due to advection of surfactant molecules by the oil flow. This increases the interfacial tension, thus making the drop less deformable for higher flow velocities. We use the deformation of the drops to infer the mean interfacial tension and from this we quantify the surface concentration of surfactants at the drop interface. A microfluidic analog of the four-roll-mill experiment is used to study the deformation and breakup of microfluidic drops. The behavior of water drops flowing in mineral oil is quantified as a function of the capillary number, Ca , which is based on the oil viscosity, drop radius, flow shear rate and equilibrium interfacial tension, both in the presence and absence of surfactants. In the absence of surfactants the deformation of the drops increases linearly with Ca . If surfactants are added to the carrier oil then, for the same value of Ca , drops deform less if the flow velocity is larger. Moreover, for a given drop size in the presence of surfactants, drops begin to split at a threshold shear rate but stop breaking if the shear rate is increased beyond a second threshold. These observations are explained by a decrease in the surfactant concentration at the surface of the drop due to advection of surfactant molecules by the oil flow. This increases the interfacial tension, thus making the drop less deformable for higher flow velocities. We use the deformation of the drops to infer the mean interfacial tension and from this we quantify the surface concentration of surfactants at the drop interface. Work supported by FONDECYT 11100204.

  16. Effect of the nature of the counterion on the properties of anionic surfactants. 5. Self-association behavior and micellar properties of ammonium dodecyl sulfate.

    PubMed

    Tcacenco, Celize M; Zana, Raoul; Bales, Barney L

    2005-08-25

    Micelles formed in water from ammonium dodecyl sulfate (AmDS) are characterized using time-resolved fluorescence quenching (TRFQ), electron paramagnetic resonance (EPR), conductivity, Krafft temperature, and density measurements. TRFQ was used to measure the aggregation number, N, and the quenching rate constant of pyrene by dodecylpyridinium chloride, k(Q). N depends only on the concentration (C(aq)) of ammonium ions in the aqueous phase whether these counterions are derived from the surfactant alone or from the surfactant plus added ammonium chloride as follows: N = N0(C(aq)/cmc0)(gamma), where N0 is the aggregation number at the critical micelle concentration in the absence of added salt, cmc0, and is equal to 77, 70, and 61 at 16, 25, and 35 degrees C, respectively. The exponent gamma = 0.22 is independent of temperature in the range 16 to 35 degrees C. The fact that N depends only on C(aq) permits the determination of the micelle ionization degree (alpha) by employing various experimental approaches to exploit a recent suggestion (J. Phys. Chem. B 2001, 105, 6798) that N depends only on C(aq). Utilizing various combinations of salt and surfactant, values of alpha were obtained by finding common curves as a function of C(aq) of the following experimental results: the Krafft temperature, N, k(Q), the microviscosity of the Stern layer determined from the rotational correlation time of a spin probe, 5-doxyl stearic acid methyl ester, and the spin-probe sensed hydration of the micelle surface. The values of alpha, determined from applying the aggregation number-based definition of alpha to all of these quantities, were within experimental uncertainty of the values alpha = 0.19, 0.20, and 0.21 derived from conductivity measurements at 16, 25, and 35 degrees C, respectively. The volume fraction of the Stern layer occupied by water decreases as N increases. For AmDS micelles, both the hydration and its decrease are predicted by a simple theory of micelle hydration by fixing the parameters of the theory for sodium dodecyl sulfate and employing no further adjustable parameters. For a given value of N, the hydration decreases as the temperature increases. PMID:16853030

  17. Influence of emulsions with and without urea on water-binding capacity of the stratum corneum

    Microsoft Academic Search

    M. GLOOR; W. GEHRING; W. WOLF

    This study was undertaken to delineate the effects of emulsions with and without urea on the water-binding behavior of the stratum corneum at different relative humidities (RH). The heels of 54 human volunteers were treated with water-in-oil (w\\/o), and oil-in-water (o\\/w) emulsions with and without urea (urea content 10%). After treatment the water content was determined by measuring the weight

  18. Effect of demulsifier partitioning on the destabilization of water-in-oil emulsions

    Microsoft Academic Search

    Young H. Kim; Darsh T. Wasan

    1996-01-01

    The factors affecting the demulsification and interfacial behavior of water-in-oil emulsions in the presence of oil-soluble demulsifiers were investigated. Using both model water-in-oil and water-in-crude oil emulsion systems with demulsifiers with different chemical structures, the effects of demulsifier partitioning on the interfacial and film rheological properties were studied. The experimental results were compared and related with the demulsifier performance. There

  19. Hydrophobically Modified Associative Polymer Solutions: Rheology and Microstructure in the Presence of Nonionic Surfactants

    Microsoft Academic Search

    Robert J. English; Jonathan H. Laurer; Richard J. Spontak; Saad A. Khan

    2002-01-01

    We report on the rheology and morphology of a hydrophobically modified alkali-swellable emulsion (HASE) polymer solubilized in alkaline media containing nonionic surfactants. The HASE polymer consists of complex alkylaryl hydrophobes composed of oligomeric nonylphenol condensates attached to a poly(ethyl acrylate-co-methacrylic acid) backbone. The complex linear viscoelastic response of the polymer in alkaline solution suggests an unentangled network with an appreciable

  20. Effect of the addition of oxybenzone or octyl-methoxycinnamate on particle size of submicron emulsions.

    PubMed

    Marti-Mestres, G; Nielloud, F; Fortuné, R; Fernandez, C; Maillols, H

    2000-03-01

    The formulation of sunscreen products requires understanding of the solubilization of these products in different vehicles to obtain aesthetic preparations and to evaluate long-term stability. For this study, two different ultraviolet (UV) filters were selected: oxybenzone (powder) and octyl-methoxycinnamate (liquid). First, the solubility of these UV filters was tested using a three-component simplex-centroid design strategy. The mixtures were prepared with three oily phases used in this field of cosmetics: liquid paraffin, isopropyl myristate, and coconut oil. A phase diagram method was used to carry out a systematic study of submicron oil-in-water emulsions. Phase diagrams were produced by diluting fixed binary mixtures with water. The surfactant consisted of polyoxyethylene-20-sorbitan monostearate/sorbitan monostearate (50/50, w/w). The oily phase contained equal quantities of each oil studied. From this water/surfactant/oil ternary system, we selected two reference emulsions with receptively 75/5/20 and 68/7/25 proportions. Photon correlation spectroscopy (PCS) was used to investigate the influence of these two UV filters at several concentrations on droplet size and distribution of the oil droplets in the material. All emulsions were stored and checked every month for 6 months. PMID:10738653

  1. Synthesis of organic rectorite with novel Gemini surfactants for copper removal

    NASA Astrophysics Data System (ADS)

    Han, Guocheng; Han, Yang; Wang, Xiaoying; Liu, Shijie; Sun, Runcang

    2014-10-01

    Three novel Gemini surfactants were used to prepare organic rectorite (OREC) under microwave irradiation, in comparison with single-chain surfactant ester quaternary ammonium salt (EQAS) and cetyltrimethyl ammonium bromide (CTAB). The structure and morphology of OREC were characterized by XRD, BET, FT-IR, TEM and TGA. The removal of Cu2+ on OREC from aqueous solution was performed. The results reveal that Gemini surfactants modified REC had larger interlayer distance and higher surface area than single-chain surfactants EQAS and CTAB, and the increasing amount or chain length of Gemini surfactants led to larger layer spacing and higher adsorption capacities. The adsorption behavior of Gemini surfactant modified REC can be better described by Freundlich adsorption isotherm model, with a maximum adsorption capacity of 15.16 mg g-1. The desorption and regeneration experiments indicate good reuse property of Gemini modified REC adsorbent. Therefore, this study may widen the utilization of Gemini surfactants modified layered silicates.

  2. Surfactant and surfactant inhibitors in meconium aspiration syndrome

    Microsoft Academic Search

    Peter A. Dargaville; Michael South; Peter N. McDougall

    2001-01-01

    Surfactant indices and inhibitors were measured in lung lavage fluid from 8 infants with meconium aspiration syndrome (MAS) who were receiving mechanical ventilation and 11 healthy control subjects. Surfactant phospholipid and surfactant protein A content in MAS was not different from that of control subjects, but concentrations of total protein, albumin, and membrane-derived phospholipid were elevated. All infants with MAS

  3. Emulsion Droplet Combustion in Microgravity: Water/Heptane Emulsions

    NASA Technical Reports Server (NTRS)

    Avedisian, C. Thomas

    1997-01-01

    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.

  4. New Fluorescent Probes Applicable to Aggregates of Fluorocarbon Surfactants

    Microsoft Academic Search

    Tadahiro Ozawa; Tsuyoshi Asakawa; Akio Ohta; Shigeyoshi Miyagishi

    2007-01-01

    We developed new benzofurazan (NBD) labeled probes for fluorocarbon surfactant systems. The fluorescence behavior depended on the solubilization site of the fluorescent probes in the surfactant aggregates. The NBD-labeled probes suffered virtually complete reduction in the presence of Na2S2O4 owing to the solubilization at the surface of 2-hydroxy-1,1,2,3,3-pentahydroperfluoroundecyldiethylammonium bromide (FC8DAB) aggregates. On the other hand, N-(3-sulfopropyl)acridinium (SPA) in FC8DAB aggregates

  5. Introducing diffusing wave spectroscopy as a process analytical tool for pharmaceutical emulsion manufacturing.

    PubMed

    Reufer, Mathias; Machado, Alexandra H E; Niederquell, Andreas; Bohnenblust, Katharina; Müller, Beat; Völker, Andreas Charles; Kuentz, Martin

    2014-12-01

    Emulsions are widely used for pharmaceutical, food, and cosmetic applications. To guarantee that their critical quality attributes meet specifications, it is desirable to monitor the emulsion manufacturing process. However, finding of a suitable process analyzer has so far remained challenging. This article introduces diffusing wave spectroscopy (DWS) as an at-line technique to follow the manufacturing process of a model oil-in-water pharmaceutical emulsion containing xanthan gum. The DWS results were complemented with mechanical rheology, microscopy analysis, and stability tests. DWS is an advanced light scattering technique that assesses the microrheology and in general provides information on the dynamics and statics of dispersions. The obtained microrheology results showed good agreement with those obtained with bulk rheology. Although no notable changes in the rheological behavior of the model emulsions were observed during homogenization, the intensity correlation function provided qualitative information on the evolution of the emulsion dynamics. These data together with static measurements of the transport mean free path (l*) correlated very well with the changes in droplet size distribution occurring during the emulsion homogenization. This study shows that DWS is a promising process analytical technology tool for development and manufacturing of pharmaceutical emulsions. PMID:25302803

  6. New surfactant for hydrate anti-agglomeration in hydrocarbon flowlines and seabed oil capture.

    PubMed

    Sun, Minwei; Firoozabadi, Abbas

    2013-07-15

    Anti-agglomeration is a promising solution for gas hydrate risks in deepsea hydrocarbon flowlines and oil leak captures. Currently ineffectiveness at high water to oil ratios limits such applications. We present experimental results of a new surfactant in rocking cell tests, which show high efficiency at a full range of water to oil ratios; there is no need for presence of the oil phase. We find that our surfactant at a very low concentration (0.2 wt.% of water) keeps the hydrate particles in anti-agglomeration state. We propose a mechanism different from the established water-in-oil emulsion theory in the literature that the process is effective without the oil phase. There is no need to emulsify the water phase in the oil phase for hydrate anti-agglomeration; with oil-in-water emulsion and without emulsion hydrate anti-agglomeration is presented in our research. We expect our work to pave the way for broad applications in offshore natural gas production and seabed oil capture with very small quantities of an eco-friendly surfactant. PMID:23660023

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

    PubMed

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

    2013-07-15

    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

  8. Determination of zinc in edible oils by flow injection FAAS after extraction induced by emulsion breaking procedure.

    PubMed

    Bakircioglu, Dilek; Topraksever, Nukte; Kurtulus, Yasemin Bakircioglu

    2014-05-15

    A new procedure using extraction induced by emulsion breaking (EIEB) procedure has been developed for extraction/preconcentration of zinc in various edible oils (canola oil, corn oil, hazelnut oil, olive oil, and sunflower oil) prior to its determination by the single line flow injection (FI) flame atomic absorption spectrometry (FAAS). Several parameters affecting the extraction efficiency of the procedure were investigated including the type and concentrations of surfactant, the concentration of HNO3, and the other operational conditions (emulsion breaking time and temperature). The limits of detection of 1.1 and 1.0 ?g L(-1) were observed for zinc when aqueous standard and oil-based standards were added to the emulsions for calibration, respectively. The proposed procedure of combining EIEB and single line FI-FAAS can be regarded as a new procedure for the determination of zinc in edible oil samples. PMID:24423524

  9. Role of interfacial protein membrane in oxidative stability of vegetable oil substitution emulsions applicable to nutritionally modified sausage.

    PubMed

    Jiang, Jiang; Xiong, Youling L

    2015-11-01

    The potential health risk associated with excessive dietary intake of fat and cholesterol has led to a renewed interest in replacing animal fat with nutritionally-balanced unsaturated oil in processed meats. However, as oils are more fluid and unsaturated than fats, one must overcome the challenge of maintaining both physical and chemical (oxidative) stabilities of prepared emulsions. Apart from physical entrapments, an emulsion droplet to be incorporated into a meat protein gel matrix (batter) should be equipped with an interactive protein membrane rather than a small surfactant, and the classical DLVO stabilization theory becomes less applicable. This review paper describes the steric effects along with chemical roles (radical scavenging and metal ion chelation) of proteins and their structurally modified derivatives as potential interface-building materials for oxidatively stable meat emulsions. PMID:26008711

  10. Hollandaise Sauce: Emulsion at Work

    NSDL National Science Digital Library

    Exploratorium

    2012-10-03

    In this activity, learners follow a recipe to make hollandaise sauce. Learners discover how cooks use egg yolks to blend oil and water together into a smooth mix. In chemistry, this mixture is known as an emulsion. Substances like egg yolks that assist with emulsification are called emulsifiers.

  11. Amphoteric water-in-oil self-inverting polymer emulsion

    SciTech Connect

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

    1985-03-19

    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.

  12. Synthesis and characterization of polyacrylonitrile nanoparticles by dispersion/emulsion polymerization process.

    PubMed

    Boguslavsky, Lior; Baruch, Sigal; Margel, Shlomo

    2005-09-01

    Polyacrylonitrile nanoparticles in sizes ranging from approximately 35 to 270 nm were prepared by dispersion/emulsion polymerization of acrylonitrile in a continuous aqueous phase in the presence of potassium persulfate as initiator and various alkyl-sulfate and sulfonate surfactants. The influence of various polymerization parameters (e.g., concentration of monomer and initiator, type and concentration of surfactant, temperature and time of polymerization, ionic strength, pH and co-solvent concentration) on the properties (e.g., size and size distribution, yield, stability, etc.) of the particles has been investigated. The polymerization of acrylonitrile may occur in two major locations: in the aqueous continuous phase (dispersion polymerization) and/or within the surfactant micelles (emulsion polymerization). A discussion concerning the role of these two mechanisms under different conditions, including comparison with previous literature, is also presented. Surface and bulk characterizations of the particles were performed by methods such as transmission and scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, zeta potential, and gravimetric measurements. PMID:16009219

  13. Surfactant Metabolism in the Neonate

    Microsoft Academic Search

    L. J. I. Zimmermann; D. J. M. T. Janssen; D. Tibboel; A. Hamvas; V. P. Carnielli

    2005-01-01

    With the use of stable isotope-labeled intravenous precursors for surfactant phosphatidylcholine (PC) synthesis, it has been shown that the de novo synthesis rates in preterm infants with respiratory distress syndrome (RDS) are very low as are turnover rates. This is consistent with animal data. Surfactant therapy does not inhibit endogenous surfactant synthesis, and prenatal corticosteroids stimulate it. With the use

  14. Half life and changes in the composition of a perfluorochemical emulsion within the vascular system of rats.

    PubMed

    Lutz, J; Stark, M

    1987-09-01

    The decline of the concentration of perfluorochemicals (PFC) after a single injection of three different doses was studied in the circulation of rats. The doses used amounted to 4.4, 10 and 14 g/kg body weight of Fluosol-DA, an emulsion of 7 parts of perfluorodecalin (FDC) and 3 parts of perfluorotripropylamine (FTPA). This also allowed testing of the composition of the emulsion remaining in the circulation and of that found in the liver. After two days a decrease of the half life from 34.0 +/- 0.7 to 17.1 +/- 4.3 h was found within the circulation at the highest dose. At the same time a change in the composition of the emulsion in the blood stream occurred, favouring the fraction of FTPA. FTPA increased from 28.3 +/- 1.4 to 54.4 +/- 8.1% on the fourth day. Whereas in the cells of the liver PFC droplets may be broken up, freed from their surfactant layer and handled according to their individual components, for PFC in the blood stream an unchanged composition should be assumed. Both results, the decreasing half life and the change in composition of the circulating emulsion may best be explained by a shrinking and instability of the emulgator film, showing the necessity for development of a superior surfactant. PMID:3684504

  15. The emulsion chamber technology experiment

    NASA Technical Reports Server (NTRS)

    Gregory, John C.

    1992-01-01

    Photographic emulsion has the unique property of recording tracks of ionizing particles with a spatial precision of 1 micron, while also being capable of deployment over detector areas of square meters or 10's of square meters. Detectors are passive, their cost to fly in Space is a fraction of that of instruments of similar collecting. A major problem in their continued use has been the labor intensiveness of data retrieval by traditional microscope methods. Two factors changing the acceptability of emulsion technology in space are the astronomical costs of flying large electronic instruments such as ionization calorimeters in Space, and the power and low cost of computers, a small revolution in the laboratory microscope data-taking. Our group at UAH made measurements of the high energy composition and spectra of cosmic rays. The Marshall group has also specialized in space radiation dosimetry. Ionization calorimeters, using alternating layers of lead and photographic emulsion, to measure particle energies up to 10(exp 15) eV were developed. Ten balloon flights were performed with them. No such calorimeters have ever flown in orbit. In the ECT program, a small emulsion chamber was developed and will be flown on the Shuttle mission OAST-2 to resolve the principal technological questions concerning space exposures. These include assessments of: (1) pre-flight and orbital exposure to background radiation, including both self-shielding and secondary particle generation; the practical limit to exposure time in space can then be determined; (2) dynamics of stack to optimize design for launch and weightlessness; and (3) thermal and vacuum constraints on emulsion performance. All these effects are cumulative and affect our ability to perform scientific measurements but cannot be adequately predicted by available methods.

  16. Mixed micellization of an anionic gemini surfactant (GA) with conventional polyethoxylated nonionic surfactants in brine solution at pH 5 and 298 K

    Microsoft Academic Search

    Tanushree Chakraborty; Soumen Ghosh

    2007-01-01

    The micellization behavior of an anionic gemini surfactant, GA with nonionic surfactants C12E8 and C12E5 in presence of 0.1 M NaCl at 298 K temperature, has been studied tensiometrically in pure and mixed states, and the related\\u000a physicochemical parameters (cmc, ?\\u000a cmc, pC\\u000a 20, ?\\u000a max, and A\\u000a min) have been evaluated. Tensiometric profile (? vs log [surfactant]), for conventional surfactants, generally

  17. Optimization of isothermal low-energy nanoemulsion formation: hydrocarbon oil, non-ionic surfactant, and water systems.

    PubMed

    Komaiko, Jennifer; McClements, David Julian

    2014-07-01

    Nanoemulsions can be fabricated using either high-energy or low-energy methods, with the latter being advantageous because of ease of implementation, lower equipment and operation costs, and higher energy efficiency. In this study, isothermal low-energy methods were used to spontaneously produce nanoemulsions using a model system consisting of oil (hexadecane), non-ionic surfactant (Brij 30) and water. Rate and order of addition of surfactant, oil and water into the final mixture were investigated to identify optimal conditions for producing small droplets. The emulsion phase inversion (EPI) and spontaneous emulsion (SE) methods were found to be the most successful, which both require the surfactant to be mixed with the oil phase prior to production. Order of addition and surfactant-to-oil ratio (SOR) influenced the particle size distribution, while addition rate and stirring speed had a minimal effect. Emulsion stability was strongly influenced by storage temperature, with droplet size increasing rapidly at higher temperatures, which was attributed to coalescence near the phase inversion temperature. Nanoemulsions with a mean particle diameter of approximately 60 nm could be produced using both EPI and SE methods at a final composition of 5% hexadecane and 1.9% Brij 30, and were relatively stable to droplet growth at temperatures <25 °C. PMID:24776664

  18. Kinetics of precipitation of surfactants. I. Anionic surfactants with calcium and with cationic surfactants

    Microsoft Academic Search

    Cheryl H. Rodriguez; Lori H. Lowery; John F. Scamehorn; Jeffrey H. Harwell

    2001-01-01

    Isoperibol calorimetry was used to measure the rates of precipitation for aqueous solutions of several anionic surfactants\\u000a with calcium and of anionic and cationic surfactants. A monomer concentration-dependent supersaturation ratio was used to\\u000a describe the relative rates of precipitation for the surfactant systems studied. This supersaturation ratio allows for the\\u000a relative rates of precipitation of any surfactant solution to be

  19. Formulation and Evaluation of a Vitamin C Multiple Emulsion

    Microsoft Academic Search

    S. Farahmand; H. Tajerzadeh; E. S. Farboud

    2006-01-01

    Multiple phase emulsions are increasingly used as alter- natives to simple emulsions in personal care products. One of the major advantages of these emulsions over simple emul- sions is slow and controlled release of their ingredients. Other favorite cosmetic characteristics of multiple emulsions include occlusivity (in O\\/W\\/O emulsions), esthetics and consumer acceptance. Vitamin C (ascorbic acid) has been widely used

  20. pH-induced inversion of water-in-oil emulsions to oil-in-water high internal phase emulsions (HIPEs) using core cross-linked star (CCS) polymer as interfacial stabilizer.

    PubMed

    Chen, Qijing; Deng, Xiaoyong; An, Zesheng

    2014-06-01

    A pH-responsive core cross-linked star (CCS) polymer containing poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) arms was used as an interfacial stabilizer for emulsions containing toluene (80 v%) and water (20 v%). In the pH range of 12.1-9.3, ordinary water-in-oil emulsions were formed. Intermediate multiple emulsions of oil-in-water-in-oil and water-in-oil-in-water were formed at pH 8.6 and 7.5, respectively. Further lowering the pH resulted in the formation of gelled high internal phase emulsions of oil-in-water type in the pH range of 6.4-0.6. The emulsion behavior was correlated with interfacial tension, conductivity and configuration of the CCS polymer at different pH. PMID:24700484

  1. Disperse dyeing of polyester fiber using gemini surfactants containing ammonium cations as auxiliaries

    Microsoft Academic Search

    Tae-Soo Choi; Yoshio Shimizu; Hirofusa Shirai; Kunihiro Hamada

    2001-01-01

    The dyeing behavior of the disperse dye, 1,4-diaminoanthraquinone (1,4-DAA), on polyester fiber in the presence of two cationic gemini surfactants, propanediyl-?,?-bis(dimethyldodecylammonium bromide) (DC3-12) and hexanediyl-?,?-bis(dimethyldodecylammonium bromide) (DC6-12) as auxiliaries, was investigated, and compared with that obtained in the presence of the corresponding conventional surfactant, dodecyltrimethylammonium bromide (C12C1NBr). The dyeing rate in the presence of the gemini surfactants was larger than

  2. Characterization of a Two?Aqueous Phase System Containing a Nonionic Surfactant

    Microsoft Academic Search

    K. Teixeira da Silva De La Salles; J. P. Canselier; C. Gourdon

    2005-01-01

    A surfactant?containing two?aqueous phase system is composed of a coacervate (surfactant?rich) phase and a dilute one (surfactant?poor). This work aims at characterizing such a two?phase system by using a recently developed optical analyzer: Turbiscan LAb Expert. This optical device allows investigating the behavior of concentrated dispersed media through light transmission or back?scattering measurements at constant temperature. Above the cloud point

  3. Surfactant waterflooding oil recovery method

    SciTech Connect

    Kalfoglou, G.

    1981-10-27

    Disclosed is a novel surfactant fluid and an oil recovery method using the fluid for recovering oil from subterranean formations thereof by surfactant waterflooding process. The fluid comprises water and at least one surfactant, preferably including an alkylpolyalkoxyalkylene sulfonate or an alkylarylpolyalkoxyalkylene sulfonate and as an additive for reducing the rigidity of the interfacial film, a silicapolydialkylsiloxane such as a silica-polydimethylsiloxane. Reduction in rididity of the interfacial film occupied by surfactant molecules of which the hydrophobic portion is dissolved in the oil phase and the hydrophilic portion is dissolved in the aqueous phase, improves the effectiveness of the surfactant fluid for recovering oil from subterranean formations.

  4. Systematic characterization of oil-in-water emulsions for formulation design.

    PubMed

    Roland, I; Piel, G; Delattre, L; Evrard, B

    2003-09-16

    Oil-in-water emulsions varying in surfactant concentration and manufacturing process were prepared. About 10 experiments were performed to characterize them. The goal of this research was to find out which tests should systematically be carried out to assess efficiently the stability and the properties of an emulsified preparation. Thus, formulation design requires at least the measurement of the droplet size, the determination of the zeta potential, a TurbiScan analysis, the investigation of the stability under centrifugation and freeze/thaw cycles. If the emulsion contains an active substance, stability under storage at 4 degrees C and microscopic analysis are relevant. Quality control should be improved by measurements of viscosity and pH. PMID:12954183

  5. The effect of butter grains on physical properties of butter-like emulsions.

    PubMed

    Rønholt, Stine; Buldo, Patrizia; Mortensen, Kell; Andersen, Ulf; Knudsen, Jes C; Wiking, Lars

    2014-04-01

    Milk fat exists as globules in its natural state in milk. The potential of using globular fat to modulate the rheological properties and crystallization behavior in butter-like emulsions was studied in the present work. We conducted a comparative study of butter-like emulsions, with a fat phase consisting of 0, 10, 25, 50, or 100% anhydrous milk fat (AMF), the remaining fat being butter grains, and all samples containing 20% water, to obtain systematic variation in the ratio of globular fat. All emulsions were studied over 4wk of storage at 5°C. By combining small and large deformation rheology, we conducted a detailed characterization of the rheological behavior of butter-like emulsions. We applied differential scanning calorimetry to monitor thermal behavior, confocal laser scanning microscopy for microstructural analysis, and low-field pulsed nuclear magnetic resonance spectrometry to measure solid fat content. By combining these techniques, we determined that increasing the fraction of globular fat (by mixing with butter grains) decreases the hardness of butter-like emulsions up to an order of magnitude at d 1. However, no difference was observed in thermal behavior as a function of butter grain content, as all emulsions containing butter grains revealed 2 endothermal peaks corresponding to the high (32.7°C ± 0.6) and medium (14.6°C ± 0.1) melting fractions of fatty acids. In terms of microstructure, decreasing the amount of butter grains in the emulsions resulted in formation of a denser fat crystal network, corresponding to increased hardness. Moreover, microstructural analysis revealed that the presence of butter grains resulted in faster formation of a continuous fat crystal network compared with the 100% AMF sample, which was dominated by crystal clusters surrounded by liquid oil. During storage, hardness remained stable and no changes in thermal behavior were observed, despite an increase in solid fat content of up to 5%. After 28d of storage, we observed no difference in either microstructural or rheological properties, indicating that formation of primary bonds occurs primarily within the first day of storage. The rheological behavior of butter-like emulsions is not determined solely by hardness, but also by stiffness related to secondary bonds within the fat crystal network. The complex rheological behavior of milk fat-based emulsions is better characterized using multiple parameters. PMID:24485691

  6. Diseases of pulmonary surfactant homeostasis.

    PubMed

    Whitsett, Jeffrey A; Wert, Susan E; Weaver, Timothy E

    2015-01-01

    Advances in physiology and biochemistry have provided fundamental insights into the role of pulmonary surfactant in the pathogenesis and treatment of preterm infants with respiratory distress syndrome. Identification of the surfactant proteins, lipid transporters, and transcriptional networks regulating their expression has provided the tools and insights needed to discern the molecular and cellular processes regulating the production and function of pulmonary surfactant prior to and after birth. Mutations in genes regulating surfactant homeostasis have been associated with severe lung disease in neonates and older infants. Biophysical and transgenic mouse models have provided insight into the mechanisms underlying surfactant protein and alveolar homeostasis. These studies have provided the framework for understanding the structure and function of pulmonary surfactant, which has informed understanding of the pathogenesis of diverse pulmonary disorders previously considered idiopathic. This review considers the pulmonary surfactant system and the genetic causes of acute and chronic lung disease caused by disruption of alveolar homeostasis. PMID:25621661

  7. SURFACTANTS AND SUBSURFACE REMEDIATION

    EPA Science Inventory

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

  8. Chemical systems for improved oil recovery: Phase behavior, oil recovery, and mobility control studies

    Microsoft Academic Search

    F. Llave; B. Gall; H. Gao; L. Scott; I. Cook

    1995-01-01

    Selected surfactant systems containing a series of ethoxylated nonionic surfactants in combination with an anionic surfactant system have been studied to evaluate phase behavior as well as oil recovery potential. These experiments were conducted to evaluate possible improved phase behavior and overall oil recovery potential of mixed surfactant systems over a broad range of conditions. Both polyacrylamide polymers and Xanthan

  9. Monte Carlo simulation of mixed nonionic Brij surfactants in water.

    PubMed

    Yahya, Ruzanna; Karjiban, Roghayeh Abedi; Basri, Mahiran; Rahman, Mohd Basyaruddin Abdul; Girardi, Mauricio

    2014-11-01

    Nonionic surfactants such as the Brij® series are important in the preparation of transdermal drug nanodelivery products using nanoemulsions because of their low toxicity and low irritancy. Here, Monte Carlo (MC) simulation was used to examine the physical behavior of the model deterministic system by using sampling procedures. Metropolis MC simulations were run on three mixtures of two different nonionic surfactants, Brij92 and Brij96, with different compositions in aqueous solution. The system was simulated in the canonical ensemble with constant temperature, volume and number of molecules. Hence, the acceptance ratio for single atom moves of the mixed surfactants increased as the concentration of surfactants increased from 0.494 to 0.591. The lowest total energy for the mixed surfactant systems was -99,039 kcal mol(-1) due to the interaction between all molecules in the system simulated. The physicochemical properties of models such as the radius of gyration and radial distribution function, were also determined. These observations indicate that the behavior and physicochemical of mixed surfactant and PKOEs nanoemulsion systems were described adequately during the simulation. PMID:25381172

  10. Properties of oil/water emulsions affecting the deposition, clearance, and after-feel sensory perception of oral coatings.

    PubMed

    Camacho, Sara; den Hollander, Elyn; van de Velde, Fred; Stieger, Markus

    2015-03-01

    The aims of this study were to investigate the influence of (i) protein type, (ii) protein content, and (iii) viscosity of o/w emulsions on the deposition and clearance of oral oil coatings and after-feel perception. Oil fraction (m(oil)/cm(2)(tongue)) and after-feel perception differed considerably between emulsions which do not flocculate under in mouth conditions (Na-caseinate) and emulsions which flocculate under in mouth conditions (lysozyme). The irreversible flocculation of lysozyme stabilized emulsions caused slower oil clearance from the tongue surface compared to emulsions stabilized with Na-caseinate. Protein content had a negative relation with oil fraction for lysozyme stabilized emulsions and no relation for Na-caseinate stabilized emulsions immediately after expectoration. Viscosity differences did not affect oil fraction, although the presence of thickener decreased deposition of oil on tongue. We conclude that after-feel perception of o/w emulsions is complex and depends on the deposited oil fraction, the behavior of proteins in mouth, and thickeners. PMID:25682813

  11. Structuring of colloidal particles at interfaces and the relationship to food emulsion and foam stability.

    PubMed

    Dickinson, Eric

    2015-07-01

    We consider the influence of spherical colloidal particles on the structure and stabilization of dispersions, emulsions and foams. Emphasis is placed on developments in the use of the methods of liquid state theory and computer simulation to understand short-range structuring of concentrated colloidal dispersions and ordering of particle layers near surfaces and within liquid films. Experimental information on the structuring of surfactant micelles and caseinate particles in thin liquid films is described, including an assessment of the effect of particle polydispersity on depletion interactions and kinetic structural stabilization. We specifically discuss the relevance of some of these structural concepts to the stability of food colloids. PMID:25446956

  12. Ultrasmall biocompatible nanocomposites: a new approach using seeded emulsion polymerization for the encapsulation of nanocrystals.

    PubMed

    Kloust, Hauke; Pöselt, Elmar; Kappen, Sascha; Schmidtke, Christian; Kornowski, Andreas; Pauer, Werner; Moritz, Hans-Ulrich; Weller, Horst

    2012-05-01

    We report a novel approach of seeded emulsion polymerization in which nanocrystals are used as seeds. Ultrasmall biocompatible polymer-coated nanocrystal with sizes between 15 and 110 nm could be prepared in a process that avoids any treatment with high shear forces or ultrasonication. The number of nanocrystals per seed, the size of the seeds, and the shell thickness can be independently adjusted. Single encapsulated nanocrystals in ultrasmall nanobeads as well as clusters of nanocrystals can be obtained. Polysorbat-80 was used as surfactant. It consists of poly(ethylene glycol) (PEG) chains, giving the particles outstanding biofunctional characteristics such as a minimization of unspecific interactions. PMID:22497455

  13. Thermally stable emulsion explosive composition

    SciTech Connect

    Sudweeks, W.B.; Lawrence, L.D.

    1982-03-30

    A thermally stable, cap-sensitive, water-in-oil emulsion explosive composition is described which has a discontinuous aqueous oxidizer salt solution phase containing calcium nitrate, a continuous oil or water-immiscible liquid or organic phase, an emulsifier, and a density reducing agent. The salt solution contains calcium nitrate in an amount of at least 20% by weight based on the total composition. 9 claims.

  14. Formation and stability of nano-emulsions

    Microsoft Academic Search

    Tharwat Tadros; P Izquierdo; J Esquena; C Solans

    2004-01-01

    This review describes the principles of formation and stability of nano-emulsions. It starts with an introduction highlighting the main advantages of nano-emulsions over macroemulsions for personal care and cosmetic formulations. It also describes the main problems with lack of progress on nano-emulsions. The second section deals with the mechanism of emulsification and the dynamic light scattering technique for measurement of

  15. Demulsification of bitumen emulsions using polyureas

    SciTech Connect

    Mccoy, D.R.; Young, K.B.

    1983-05-24

    A process for recovering bitumen from oil-in-water (O/w) emulsions is disclosed wherein water soluble demulsifiers are used. These demulsifiers are polyureas of average molecular weight greater than about 5,000 prepared by the reaction between a polyisocyanate and a polyoxyalkylenediamine. To resolve the bituminous petroleum emulsions, the process is carried out between 25/sup 0/ and 160/sup 0/ C wherein the demulsifier of the invention is contacted with the bituminous emulsion.

  16. Demulsification of bitumen emulsions using cationic polymers

    SciTech Connect

    Mccoy, D.R.; Young, K.B.

    1983-05-10

    A process for recovering bitumen from oil-in-water (O/w) emulsions is disclosed wherein water soluble demulsifiers are used. These demulsifiers are cationic polymers of equal to or greater than about 2,000 molecular weight obtained by the reaction of polyalkoxydiamines with epihalohydrins. To resolve the bituminous petroleum emulsions, the process is carried out between 25/sup 0/ and 160/sup 0/ C wherein the demulsifier of the invention is contacted with the bituminous emulsion.

  17. Demulsification of bitumen emulsions using ionenes

    SciTech Connect

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

    1983-09-13

    A process for recovering bitumen from oil-in-water (O/W) emulsions is disclosed wherein water-soluble demulsifiers are used. These demulsifiers are ionenes prepared generally by reaction of ditertiary amines and dihalides. To resolve the bituminous petroleum emulsions, the process is carried out between 25/sup 0/ and 160/sup 0/C wherein the demulsifier of the invention is contacted with the bituminous emulsion.

  18. Coalescence of water-in-shale oil emulsions

    SciTech Connect

    Menon, V.B.; Wasan, D.T.

    1984-01-01

    The coalescence and interfacial behavior of water-in-shale oil emulsions in the presence of chemical additives was studied using photomicrographic analysis. Both the coalescence and flocculation rate constants were determined as a function of the demulsifier concentration. The coalescence rates increased and the interfacial viscosity decreased with an increase in the temperature. These changes are due to the decrease in bulk and interfacial viscosities with increase in temperature, higher temperature facilitating better film drainage and hence better coalescence rates. The overall coalescence rate goes through a maximum as the speed of agitation is increased. This maximum may be explained by the mechanism of flocculation and redispersion. The presence of solids was seen to significantly increase the stability of these emulsions. 17 references, 14 figures, 6 tables.

  19. Chemical demulsification of petroleum emulsions using oil-soluable demulsifiers

    SciTech Connect

    Krawczyk, M.A.; Wasan, D.T.; Shetty, C.S. (Dept. of Chemical Engineering, Illinois Inst. of Technology, Chicago, IL (US))

    1991-02-01

    This paper investigates the factors affecting the coalescence and interfacial behavior of water- in-crude-oil emulsions in the presence of oil-soluble demulsifiers. The emulsion-breaking characteristics and interfacial properties of East Texas Crude and a model system were compared. The variation of interfacial tension with demulsifier concentration for the model system was ascertained by measuring the interfacial tensions between the oil and water phase. Interfacial activity, adsorption kinetics, and partitioning were shown to be the most important parameters governing demulsifier performance. A conceptual model of drop-drop coalescence process in demulsification was presented which indicates that the interfacial activity of the demulsifier must be high enough to suppress the interfacial tension gradient. This accelerates the rate of film drainage, thus promoting coalescence.

  20. Nanostructure of electrically conducting polyaniline prepared by a novel emulsion polymerization process

    SciTech Connect

    Liu, J.; Kinlen, P.J.; Graham, C.R.

    1998-07-01

    A soluble polyaniline (PANI) salt with moderate conductivity was synthesized by a novel emulsion polymerization process. The conductivity of the processed PANI films can be substantially increased by treating the polymer films with surfactants or with low molecular weight alcohols. Transmission electron microscopy (TEM) images of thin polymer films revealed the existence of small islands of conducting PANI embedded in a non-conducting, dopant matrix. The conductivity of the PANI films is affected by the spatial distribution and the connectivity of these small islands. The conductivity enhancement observed upon treatment with surfactants is due to self-assembly of conducting PANI molecules into an interconnected network morphology. In the case of alcohol treatment the film conductivity is enhanced due to extraction of excess dopant phase and the subsequent densification of PANI islands to form highly conducting pathways.

  1. Preparation of aqueous dispersion of thermoplastic sizing agent for carbon fiber by emulsion/solvent evaporation

    NASA Astrophysics Data System (ADS)

    Giraud, Isabelle; Franceschi-Messant, Sophie; Perez, Emile; Lacabanne, Colette; Dantras, Eric

    2013-02-01

    In this work, different sizing agent aqueous dispersions based on polyetherimide (PEI) were elaborated in order to improve the interface between carbon fibers and a thermoplastic matrix (PEEK). The dispersions were obtained by the emulsion/solvent evaporation technique. To optimize the stability and the film formation on the fibers, two surfactants were tested at different concentrations, with different concentrations of PEI. The dispersions obtained were characterized by dynamic light scattering (DLS) and the stability evaluated by analytical centrifugation (LUMiFuge). The selected dispersions were tested for film formation ability by scanning electron microscopy (SEM), and the sizing performance was assessed by observation of the fiber/matrix interface by SEM. The results revealed that an aqueous dispersion of PEI, stabilized by sodium dodecyl sulfate as the surfactant, led to very stable sizing agent aqueous dispersion with ideal film formation and better interface adhesion.

  2. A modified emulsion gelation technique to improve buoyancy of hydrogel tablets for floating drug delivery systems.

    PubMed

    Yom-Tov, Ortal; Seliktar, Dror; Bianco-Peled, Havazelet

    2015-10-01

    The use of buoyant or floating hydrogel tablets is of particular interest in the sustained release of drugs to the stomach. They have an ability to slow the release rates of drugs by prolonging their absorption window in the upper part of the gastrointestinal (GI) tract. In this study we synthesized bioactive hydrogels that have sustainable release rates for drugs in the stomach based on a hydrogel preparation technique that employs emulsifying surfactants. The emulsion gelation technique, which encapsulates oil droplets within the hydrogels during crosslinking, was used to decrease their specific gravity in aqueous environments, resulting in floating drug release depots. Properties such as swelling, buoyancy, density and drug release were manipulated by changing the polymer concentrations, surfactant percentages and the oil:polymer ratios. The relationship between these properties and the hydrogel's floating lag time was documented. The potential for this material to be used as a floating drug delivery system was demonstrated. PMID:26117764

  3. Deactivation efficiency of stabilized bactericidal emulsions.

    PubMed

    Vyhnalkova, Renata; Eisenberg, Adi; van de Ven, Theo G M

    2011-09-20

    Biocide emulsions stabilized with various stabilizing agents were prepared and characterized, and their efficiency in bacteria deactivation was evaluated. A number of stabilizing agents were tested for their stabilizing effect on emulsions of thiocyanomethylthiobenzothiazole (TCMTB) biocide. Two agents, the most successful in stabilizing the biocide, were chosen for further studies: high molecular weight polyethyleneimine (PEI) and an amphiphilic block copolymer of poly(caprolactone)-b-poly(acrylic acid) (PCL(33)-b-PAA(33)). The emulsion droplet sizes varied between 325 and 500 nm. Deactivation of bacteria was studied by exposing E. coli ATCC 11229 bacteria dispersions to emulsions stabilized by positively charged PEI or negatively charged PCL-b-PAA micelles and by measuring their absorbance; E. coli do not grow with time in the presence of biocide emulsions. PEI molecules alone act as biocide and deactivate the bacteria. PCL-b-PAA micelles as stabilizing agent do not affect the growth of the E. coli ; bacteria are deactivated by TCMTB released from the emulsion droplets. The kinetics of emulsion dissolution studies revealed for both stabilizing agents a decrease in droplet size with time while the emulsions were subjected to dialysis. The biocide was released from the emulsions within ?250 min; the droplet shells consist mostly of PEI or PCL-b-PAA insoluble complexes with the biocide, which do not dissolve during dialysis. SEM images confirm the presence of residual crumbled shells with holes after 24 h of dialysis. PMID:21823610

  4. Biopolymer-based structuring of liquid oil into soft solids and oleogels using water-continuous emulsions as templates.

    PubMed

    Patel, Ashok R; Rajarethinem, Pravin S; Cludts, Nick; Lewille, Benny; De Vos, Winnok H; Lesaffer, Ans; Dewettinck, Koen

    2015-02-24

    Physical trapping of a hydrophobic liquid oil in a matrix of water-soluble biopolymers was achieved using a facile two-step process by first formulating a surfactant-free oil-in-water emulsion stabilized by biopolymers (a protein and a polysaccharide) followed by complete removal of the water phase (by either high- or low-temperature drying of the emulsion) resulting in structured solid systems containing a high concentration of liquid oil (above 97 wt %). The microstructure of these systems was revealed by confocal and cryo-scanning electron microscopy, and the effect of biopolymer concentrations on the consistency of emulsions as well as the dried product was evaluated using a combination of small-amplitude oscillatory shear rheometry and large deformation fracture studies. The oleogel prepared by shearing the dried product showed a high gel strength as well as a certain degree of thixotropic recovery even at high temperatures. Moreover, the reversibility of the process was demonstrated by shearing the dried product in the presence of water to obtain reconstituted emulsions with rheological properties comparable to those of the fresh emulsion. PMID:25133865

  5. Study of adsorption kinetics of surfactants onto polyethersulfone membrane surface using QCM-D

    Microsoft Academic Search

    Sean X. Liu; Jun-Tae Kim

    2009-01-01

    The adsorption kinetics of surfactants onto the crystal surface spin-coated with a thin layer of a model membrane material, polyethersulfone was monitored through measurements of frequency and dissipation shifts simultaneously using a quartz crystal microbalance with dissipation (QCM-D) apparatus. In this study, the viscoelastic behaviors of the adsorbed surfactant layers of sodium laureth sulfate, cocamidopropyl betaine and their mixed solution

  6. Effects of surfactants on the spectral behaviour of calcein (II): a method of evaluation

    Microsoft Academic Search

    Adriana Memoli; Luisa Gabriella Palermiti; Valter Travagli; Franco Alhaique

    1999-01-01

    The spectral behavior of calcein, a water-soluble self quenching fluorescent marker often used in biomedical analysis, can be considerably affected by the prescence of surfactants. With this study we intend to obtain further information on the photophysical properties of calcein, in the presence of surfactants and in the concentration range commonly used to investigate the release of such marker from

  7. Adsorption\\/aggregation of surfactants and their mixtures at solid–liquid interfaces

    Microsoft Academic Search

    P. Somasundaran; L. Huang

    2000-01-01

    Adsorption of surfactants and polymers at solid–liquid interfaces is used widely to modify interfacial properties in a variety of industrial processes such as flotation, ceramic processing, flocculation\\/dispersion, personal care product formulation and enhanced oil recovery. The behavior of surfactants and polymers at interfaces is determined by a number of forces, including electrostatic attraction, covalent bonding, hydrogen bonding, hydrophobic bonding, and

  8. Kinetics of precipitation of surfactants. II. Anionic surfactant mixtures

    Microsoft Academic Search

    Cheryl H. Rodriguez; John F. Scamehorn

    2001-01-01

    Precipitation kinetics were measured for calcium-induced precipitation of mixtures of two anionic surfactants. The overall\\u000a time required for precipitation to occur increased dramatically in specific ranges of compositions for the surfactant mixtures\\u000a when compared to single components. Adsorption of the nonprecipitating surfactant onto the precipitate surface was shown to\\u000a be responsible for this remarkable synergism. The higher the supersaturation of

  9. Emulsion Liquid Membrane Removal of Arsenic and Strontium from Wastewater: AN Experimental and Theoretical Study.

    NASA Astrophysics Data System (ADS)

    Zhou, Ding-Wei

    The emulsion liquid membrane (ELM) technique has been successfully applied on the removal of arsenic (As) from metallurgical wastewater and the removal of strontium (Sr) from radioactive wastewater. This study consisted of experimental work and mathematical modeling. Extraction of arsenic by an emulsion liquid membrane was firstly investigated. The liquid membrane used was composed of 2-ethylhexyl alcohol (2EHA) as the extractant, ECA4360J as the surfactant, and Exxsol D-80 solvent (or heptane) as the diluent. The sulfuric acid and sodium hydroxide solutions were used as the external and internal phases, respectively. The arsenic removal efficiency reached 92% within 15 minutes in one stage. Extraction and stripping chemistries were postulated and investigated. It was observed that extraction efficiency and rate increase with the increase of acidic strength and alkali strength in the external and internal phases, respectively. It was also observed that the removal selectivity of arsenic over copper is extremely high. Strontium-90 is one of the major radioactive metals appearing in nuclear wastewater. The emulsion liquid membrane process was investigated as a separation method by using the non-radioactive ^{87}Sr as its substitute. In our study, the membrane phase was composed of di-(2-ethylhexyl) phosphoric acid (D2EHPA) as the extractant, ECA4360J as the surfactant and Exxsol D-80 as the diluent. A sulfuric acid solution was used in the internal phase as the stripping agent. The pH range in the external phase was determined by the extraction isotherm. Under the most favorable operating condition, the strontium removal efficiency can reach 98% in two minutes. Mass transfer of the emulsion liquid membrane (ELM) system was modeled mathematically. Our model took into account the following: mass transfer of solute across the film between the external phase and the membrane phase, chemical equilibrium of the extraction reaction at the external phase-membrane interface, simultaneous diffusion of the solute-carrier complex inside the globule membrane phase and stripping of the complex at the membrane-internal phase interface, chemical equilibrium of the stripping reaction at the membrane-internal phase interface and leakage of the solute from the internal phase to the external phase. Resulting simultaneous partial differential equations were solved analytically by the Laplace transform method. Four dimensionless groups were found with special physical meanings to characterize the emulsion liquid membrane systems. It not only predicted the concentration of solute in the external phase versus time, but also gave the concentration profile inside the membrane globule and the interfacial concentration at the external-membrane phase interface at different time. The model predicted very well the experimental data obtained from the removal of arsenic and strontium by the emulsion liquid membranes.

  10. Influence of Liquid-Layer Thickness on Pulmonary Surfactant Spreading and Collapse

    PubMed Central

    Siebert, Trina A.; Rugonyi, Sandra

    2008-01-01

    Pulmonary surfactant spreads on the thin (?0.1 ?m) liquid layer that lines the alveoli, forming a film that reduces surface tension and allows normal respiration. Pulmonary surfactant deposited in vitro on liquid layers that are several orders of magnitude thicker, however, does not reach the low surface tensions (?0.001 N/m) achieved in the lungs during exhalation when the surfactant film compresses. This is due to collapse, a surface phase transition during which the surfactant film, rather than decreasing surface tension by increasing its surface density, becomes thicker at constant surface tension (?0.024 N/m). Formation of the collapse phase requires transport of surfactant to collapse sites, and this transport can be hindered in thinner liquid layers by viscous resistance to motion. Our objective is to determine the effect of the liquid-layer thickness on surfactant transport, which might affect surfactant collapse. To this end, we developed a mathematical model that accounts for the effect of the liquid-layer thickness on surfactant transport, and focused on surfactant spreading and collapse. Model simulations showed a marked decrease in collapse rates for thinner liquid layers, but this decrease was not enough to completely explain differences in surfactant film behavior between in vitro and in situ experiments. PMID:18676658

  11. Electrophoretic separations in poly(dimethylsiloxane) microchips using a mixture of ionic and zwitterionic surfactants

    PubMed Central

    Guan, Qian; Noblitt, Scott D.; Henry, Charles S.

    2012-01-01

    The use of mixtures of ionic and zwitterionic surfactants in poly(dimethylsiloxane) (PDMS) microchips is reported. The effect of surfactant concentration on EOF was studied for a single anionic surfactant (sodium dodecyl sulfate, SDS), a single zwitterionic surfactant (N-tetradecylammonium-N,N-dimethyl-3-ammonio-1-propanesulfonate, TDAPS), and a mixed SDS/TDAPS surfactant system. SDS increased the EOF as reported previously while TDAPS showed an initial increase in EOF followed by a reduction at higher concentrations. When TDAPS was added to a solution containing SDS, the EOF decreased in a concentration dependent manner. The EOF for all three surfactant systems followed expected pH trends, with increasing EOF at higher pH. The mixed surfactant system allowed tuning of the EOF across a range of pH and concentration conditions. After establishing the EOF behavior, the adsorption/desorption kinetics were measured and showed a slower adsorption/desorption rate for TDAPS than SDS. Finally, the separation and electrochemical detection of model catecholamines in buffer and reduced glutathione (GSH) in red blood cell lysate using the mixed surfactant system were explored. The mixed surfactant system provided shorter analysis times and/or improved resolution when compared to the single surfactant systems. PMID:22222982

  12. Stable emulsions with thermally responsive microstructure and rheology using poly(ethylene oxide) star polymers as emulsifiers.

    PubMed

    Saigal, Trishna; Yoshikawa, Alex; Kloss, Dennis; Kato, Masanari; Golas, Patricia Lynn; Matyjaszewski, Krzysztof; Tilton, Robert D

    2013-03-15

    Poly(ethylene oxide) star polymers (PEO stars) were prepared by atom transfer radical polymerization of 2000 molecular weight PEO methacrylate macromonomer with divinylbenzene as a crosslinking co-monomer. With an average of 460 arms per star, these PEO stars had a 12 nm radius of gyration that is consistent with a dense polymer core surrounded by an extended PEO corona. The PEO stars were extremely efficient emulsifiers, stabilizing cyclohexane-in-water or xylene-in-water emulsions against coalescence for several months at aqueous phase concentrations as low as 0.008 wt% or 0.01 wt%, respectively. Consistent with their emulsifying performance, PEO star adsorption decreased interfacial tension by approximately 22 mN/m and imparted significant dilatational elasticity to the xylene/water interface. PEO stars were thermally responsive, displaying a cloud point upon heating in water that was tuned by addition of kosmotropic electrolytes, and they in turn produced xylene-in-water emulsions that were thermally responsive in terms of the dispersion state of the emulsion droplets and the emulsion rheology. Emulsions prepared at room temperature mainly had non-flocculated droplets. Heating such an emulsion above the cloud point temperature triggered droplet flocculation, but not coalescence, that in turn was associated with increased viscous and elastic moduli of the emulsion measured after cooling back to room temperature. Emulsions that initially were homogenized above the cloud point temperature and then cooled showed neither droplet flocculation nor rheological thickening relative to emulsions that were prepared and held at room temperature. A mechanism based on the bridging behavior of PEO stars adsorbed at the droplet/water interface is postulated to explain this thermal response of the emulsion microstructure. PMID:23266031

  13. Organic acid salts as surfactants for enhanced oil recovery

    SciTech Connect

    Donnellan, W.H. III

    1987-01-01

    Surfactants suitable for application in Enhanced Oil Recovery were produced from C/sub 22/ and C/sub 26/ paraffinic and naphthenic petroleum fractions by a two-step process. The hydrocarbon feedstocks were first non-catalytically oxidized in the vapor phase in a steam-moderated reactor, at an average reaction temperature of about 304 to 308 C, and atmospheric pressure. The principal products expected were 3-, 4-, and 5-membered cyclic ethers; however, this work suggests that carboxylic acids, esters, lactones, or other saponifiable materials also were produced. The second step in the preparation of the surfactants was the heating of the oxidized products with base to form surface-active organic acid salts. The mixture was allowed to separate, the unreacted oil layer was removed, and the aqueous phase was retained as the surfactant solution. The oxidized products were evaluated by sulfuric acid solubility (to determine the proportions of oxygenated compounds and olefins), clay percolation (to determine the proportion of oxygenated compounds), titration (to determine the acidity), and IR Carbon-13 NMR spectroscopy (to determine some of the functional groups present). Surfactant solutions were evaluated predominantly by the interfacial behavior as determined by the spinning drop technique. Interfacial tensions were determined both before and after the surfactant solutions were subjected to the static adsorption test developed in this work. The results from the static adsorption test were found to accurately predict a surfactant solution's potential for oil recovery. Tertiary recoveries of up to 55% of residual oil were obtained.

  14. Synergetic effect based gel-emulsions and their utilization for the template preparation of porous polymeric monoliths.

    PubMed

    Miao, Qing; Chen, Xiangli; Liu, Lingling; Peng, Junxia; Fang, Yu

    2014-11-18

    A polymerizable cholesteryl derivative (COA) was synthesized and used as a stabilizer for creating gel-emulsions with water in polymerizable monomers, of which they are styrene (ST), tert-butyl methacrylate (t-BMA), ethylene glycol dimethyl acrylate (EGDMA), and methyl methacrylate (MMA), etc. Interestingly, in addition to COA, the presence of a small amount of Span-80 is a necessity for the formation of the monomers containing gel-emulsions. Unlike conventional ones, the volume fraction of the dispersed phase in the gel-emulsions as created could be much lower than 74%, a critical value for routine gel-emulsions. Stabilization of these gel-emulsions as created has been attributed to the synergetic effect between COA, a typical low-molecular-mass gelator (LMMG), and Span-80, a surfactant, of which the former gels the continuous phase and the latter minimizes the interfacial energy of the continuous phase and the dispersed phase. SEM observation confirmed the network structures of COA in the gel-emulsions. Rheological tests demonstrated that the storage modulus, G', and the yield stress of the gel-emulsions decrease along with increasing the volume fraction of the dispersed phase, water, provided it is not greater than 74%-a result inconsistent with the theory explaining formation of routine gel-emulsions and in support of the conclusion that the systems under study follow a different mechanism. Furthermore, unlike LMMG-based stabilizers reported earlier, the gelator, COA, created in the present study has been functioning not only as a stabilizer but also a monomer. To illustrate the conceptual advantages, the gel-emulsions of water in ST/DVB/AIBN were polymerized. As expected, the densities and internal structures of the monoliths as prepared are highly adjustable, functionalization of the materials with cholesterol has been realized, and at the same time the problem of stabilizer leaking has been avoided. A preliminary test for gas adsorption demonstrated that the monoliths as prepared are good adsorbents for some volatile organic compounds (VOCs), in particular benzene, toluene, ethylbenzene, and xylene-the famous and toxic BTEX. It is believed that the findings reported in the present work provide not only a new strategy for creating novel gel-emulsions but also a new route for functionalizing porous polymeric monoliths. PMID:25338107

  15. Perfluorochemical emulsions can increase tumor radiosensitivity

    Microsoft Academic Search

    B. A. Teicher; C. M. Rose

    1984-01-01

    An oxygen-carrying perfluorochemical emulsion enhanced the effectiveness of radiation therapy in two transplantable solid tumors in mice. The perfluorochemical emulsion had no effect on tumor growth after x-irradiation, but delayed tumor growth significantly when administered to oxygen-breathing mice before or during irradiation.

  16. Treatment of oil-in-water emulsions

    SciTech Connect

    Harrison, R.J.; Presley, C.T.

    1980-01-08

    Petroleum is separated from an ''oil-in-water'' emulsion containing water-soluble polymer prior to refining by adding amphoteric metal cations to the emulsion to form a flocculate and then treating the resulting flocculate with a strong base to recover the oil and metal.

  17. Treatment of oil-in-water emulsions

    SciTech Connect

    Presley, C.T.; Harrison, R.J.

    1980-01-08

    Petroleum is separated from an oil-in-water emulsion containing water-soluble polymer such as polyacrylamide prior to refining by adding amphoteric metal cations (Zn, Al, Sn, and Co) to the emulsion to form a flocculate and then treating the resulting flocculate with a strong base to recover the oil and metal. 11 claims.

  18. 8. Particle detectors 8.1 Emulsions

    E-print Network

    Pohl, Martin Karl Wilhelm

    8. Particle detectors 8.1 Emulsions Nuclear emulsions can be used to give 3-dimensional information-altitude balloons. A second way of measuring energetic charged particles involves scintillation detectors. Here of the detectors is low, so they are not ideal at particle energies below about 100 keV, but they are simple

  19. Synthesis and characterization ofpH-degradable nonionic surfactants and their applications in microemulsions

    NASA Astrophysics Data System (ADS)

    Iyer, Maithili Ananth

    2002-03-01

    The objective of this research is to synthesize pH-degradable surfactants and investigate their use in water-in-oil microemulsion based protein extraction. Water-in-oil microemulsions (w/o-ME's) are nanometer sized aqueous droplets dispersed in apolar solvents due to the action of surfactants. Microemulsion based protein extraction (MPE) is a quick, simple and selective method for the recovery of biornolecules. There are however four problems that limit MPE (using commercially available surfactants), namely, protein inactivation, slow or incomplete recovery of proteins, a limit to solubilization of the protein, and complete separation of the protein from the surfactant. There have been a number of approaches to solve these problems. However, this is the first approach to help resolve these issues using degradable surfactants. Degradable surfactants are capable of splitting into non-surface active species when subjected to certain conditions depending upon their structure. Using degradable surfactants would help resolve some of these problems. After completion of the extraction process, the surfactant can be subject to conditions so that it becomes 'surface-inactive' and this would help separation of the surfactant from the protein. In addition the use of nonionic surfactants also contributes positively since nonionic surfactants bind less strongly as compared to ionic surfactants. The surfactants synthesized during the course of this research comprised of polyethylene glycol (helps protein activity) as the hydrophile and a cyclic ketal as the hydrophobe. The cyclic ketal structure is susceptible to hydrolysis in the presence of mild acids. Three different surfactant systems were synthesized, with the same headgroup but different tail groups. All of them formed water-in-oil microemulsions in isooctane. The surfactants hydrolyzed (in pH 5 buffer) in an apparent zeroth order process. This is the only known research where an organic oil-soluble cleavable surfactant was synthesized, two enzymes, lysozyme and alpha-chymotrypsin (concentrations as high as 10 mg) could be solubilized in the microemulsions, and subsequently released within an hour with retention in enzyme activity. The phase behavior of the surfactant systems and the size of the microemulsions were also characterized and found to be consistent with that of commercially available nonionic surfactants.

  20. Optimization of Oil-in-Water Emulsion Stability: Experimental Design, Multiple Light Scattering, and Acoustic Attenuation Spectroscopy

    Microsoft Academic Search

    Malek Bendjaballah; Jean Paul Canselier; Rabah Oumeddour

    2010-01-01

    To find an optimal formulation of oil-in-water (O\\/W) emulsions (?o = 0.05), the effect of emulsifier nature and concentration, agitation speed, emulsifying time, storage temperature and their mutual interactions on the properties and behavior of these dispersions is evaluated by means of an experimental design (Nemrodw software). Long-term emulsion stability is monitored by multiple light scattering (Turbiscan ags) and acoustic attenuation spectroscopy

  1. Fundamental Study of Emulsions Stabilized by Soft and Rigid Particles.

    PubMed

    Li, Zifu; Harbottle, David; Pensini, Erica; Ngai, To; Richtering, Walter; Xu, Zhenghe

    2015-06-16

    Two distinct uniform hybrid particles, with similar hydrodynamic diameters and comparable zeta potentials, were prepared by copolymerizing N-isopropylacrylamide (NIPAM) and styrene. These particles differed in their styrene to NIPAM (S/N) mass ratios of 1 and 8 and are referred to as S/N 1 and S/N 8, respectively. Particle S/N 1 exhibited a typical behavior of soft particles; that is, the particles shrank in bulk aqueous solutions when the temperature was increased. As a result, S/N 1 particles were interfacially active. In contrast, particle S/N 8 appeared to be rigid in response to temperature changes. In this case, the particles showed a negligible interfacial activity. Interfacial shear rheology tests revealed the increased rigidity of the particle-stabilized film formed at the heptane-water interface by S/N 1 than S/N 8 particles. As a result, S/N 1 particles were shown to be better emulsion stabilizers and emulsify a larger amount of heptane, as compared with S/N 8 particles. The current investigation confirmed a better performance of emulsion stabilization by soft particles (S/N 1) than by rigid particles (S/N 8), reinforcing the importance of controlling softness or deformability of particles for the purpose of stabilizing emulsions. PMID:25835257

  2. Manipulating Hydrophobic Interactions in Associative Polymer Solutions via Surfactant-Cyclodextrin Complexation

    NASA Astrophysics Data System (ADS)

    Talwar, Sachin; Harding, Jonathon; Khan, Saad A.

    2008-07-01

    Associative polymers in combination with cyclodextrin (CD) provide a potent tool to manipulate the solution rheology of aqueous solutions. In this study, we discuss the viability and scope of employing surfactants in such systems to facilitate a more versatile and effective tailoring of rheological properties. A model hydrophobically modified alkali-soluble emulsion (HASE) polymer is used which forms a transient physical network of intra- and inter-molecular hydrophobic junctions in solution arising from the interactions between hydrophobic groups grafted on the polymer backbone. The presence of these hydrophobic junctions significantly enhances the solution rheological properties with both the steady state viscosity and dynamic moduli exhibiting an increase by several orders of magnitude. The ability of nonionic surfactants to modulate and recover the hydrophobic interactions in these polymer solutions in the presence of cyclodextrin is examined. The presence of either a- or ?-CD results in a dramatic decrease in viscosity and viscoelastic properties of the HASE polymer solution resulting from the encapsulation of polymer hydrophobes by CDs. Addition of nonionic surfactants to such systems promotes a competition between CDs and surfactant molecules to complex with polymer hydrophobes thereby altering the hydrophobic interactions. In this regard, nonylphenol ethoxylates (NPe) with different ethylene oxide (EO) chain lengths, which determine the surfactant hydrophilic-lipophilic balance (HLB), are used.

  3. Reverse micelles-mediated transport of lipase in liquid emulsion membrane for downstream processing.

    PubMed

    Bhavya, S G; Priyanka, B S; Rastogi, Navin K

    2012-01-01

    This work deals with the downstream processing of lipase (EC 3.1.1.3, from Aspergillus niger) using liquid emulsion membrane (LEM) containing reverse micelles for the first time. The membrane phase consisted of surfactants [cetyltrimethylammonium bromide (CTAB) and Span 80] and cosolvents (isooctane and paraffin light oil). The various process parameters for the extraction of lipase from aqueous feed were optimized to maximize activity recovery and purification fold. The mechanism of lipase transport through LEM consisted of three steps namely solubilization of lipase in reverse micelles, transportation of reverse micelles loaded with lipase through the liquid membrane, and release of the lipase into internal aqueous phase. The results showed that the optimum conditions for activity recovery (78.6%) and purification (3.14-fold) were feed phase ionic strength 0.10 M NaCl and pH 9.0, surfactants concentration (Span 80 0.18 M and CTAB 0.1 M), volume ratio of organic phase to internal aqueous phase 0.9, ratio of membrane emulsion to feed volume 1.0, internal aqueous phase concentration 1.0 M KCl and pH 7.0, stirring speed 450 rpm, and contact time 15 min. This work indicated the feasibility of LEM for the downstream processing of lipase. PMID:23011754

  4. Emulsion stability and demulsification during the direct extraction of penicillin broth.

    PubMed

    Szabó, C

    1992-06-20

    In this article, we present the factors which influence the stability of the emulsion forming under the circumstances of the direct extraction of penicillin fermentation broth and the conditions of demulsification. A laboratory method has been developed for testing demulsifiers and a quantitative evaluation of the properties determining the separation of phases has been worked out as well. It has been found that an emulsion of oil in water (o/w) forms and that this is very stable; it can be broken only by the presence of demulsifier and by using a field of centrifugal force. We have discovered that the most effective demulsifiers are cation-active surfactants for 1-4 g/L broth concentration. Furthermore, it is advantageous if the demulsifier contains a nonionic surfactant and wetting agent as well. From the 19 surface-active compounds studied in the laboratory, we found that the NADAR 107 A and ARMOGARD D-5306 demulsifiers contained the best properties for the extraction of the penicillin broth. PMID:18601110

  5. ADSORPTION OF SURFACTANT ON CLAYS

    EPA Science Inventory

    Surfactants used to enhance remediation of soils by soil washing are often lost in the process. Neither the amount nor the cause of this loss is known. It is assumed that clays present in the soil are responsible for the loss of the surfactant. In this papere, adsorption prope...

  6. Oleophilic separation of inverse emulsions

    SciTech Connect

    Kruyer, J.

    1984-02-01

    The oleophilic sieve is a patented device for separating mixtures of oil phase and aqueous phase wherein the aqueous phase passes through the sieve apertures and the oil phase is captured by the sieve surfaces upon contact. This method achieves very efficient separations and is not adversely affected by solids in the aqueous phase or by the density of the oil phase. Normally the mixture is agglomerated during the separation process to increase the oil phase particle size and to permit it to be more readily captured by the sieve. The oleophilic sieve may be used to separate a large variety of mixtures and has been tested with mined tar sand slurries, middlings, tailings, tailings pond sludge and inverse emulsions produced from in-situ steam drive facilities. For emulsions, a demulsifier is normally required but no diluent is used to recover the bitumen or heavy oil from the aqueous phase. This results in high bitumen recovery, clean water effluents and minimizes overall separation costs.

  7. Transient exposure of pulmonary surfactant to hyaluronan promotes structural and compositional transformations into a highly active state.

    PubMed

    Lopez-Rodriguez, Elena; Cruz, Antonio; Richter, Ralf P; Taeusch, H William; Pérez-Gil, Jesús

    2013-10-11

    Pulmonary surfactant is a lipid-protein complex that lowers surface tension at the respiratory air-liquid interface, stabilizing the lungs against physical forces tending to collapse alveoli. Dysfunction of surfactant is associated with respiratory pathologies such as acute respiratory distress syndrome or meconium aspiration syndrome where naturally occurring surfactant-inhibitory agents such as serum, meconium, or cholesterol reach the lung. We analyzed the effect of hyaluronan (HA) on the structure and surface behavior of pulmonary surfactant to understand the mechanism for HA-promoted surfactant protection in the presence of inhibitory agents. In particular, we found that HA affects structural properties such as the aggregation state of surfactant membranes and the size, distribution, and order/packing of phase-segregated lipid domains. These effects do not require a direct interaction between surfactant complexes and HA and are accompanied by a compositional reorganization of large surfactant complexes that become enriched with saturated phospholipid species. HA-exposed surfactant reaches very high efficiency in terms of rapid and spontaneous adsorption of surfactant phospholipids at the air-liquid interface and shows significantly improved resistance to inactivation by serum or cholesterol. We propose that physical effects pertaining to the formation of a meshwork of interpenetrating HA polymer chains are responsible for the changes in surfactant structure and composition that enhance surfactant function and, thus, resistance to inactivation. The higher resistance of HA-exposed surfactant to inactivation persists even after removal of the polymer, suggesting that transient exposure of surfactant to polymers like HA could be a promising strategy for the production of more efficient therapeutic surfactant preparations. PMID:23983120

  8. Polyurethane and polyurea nanoparticles based on polyoxyethylene castor oil derivative surfactant suitable for endovascular applications.

    PubMed

    Morral-Ruíz, Genoveva; Melgar-Lesmes, Pedro; García, María Luísa; Solans, Conxita; García-Celma, María José

    2014-01-30

    The design of new, safe and effective nanotherapeutic systems is an important challenge for the researchers in the nanotechnology area. This study describes the formation of biocompatible polyurethane and polyurea nanoparticles based on polyoxyethylene castor oil derivative surfactant formed from O/W nano-emulsions by polymerization at the droplet interfaces in systems composed by aqueous solution/Kolliphor(®) ELP/medium chain triglyceride suitable for intravenous administration. Initial nano-emulsions incorporating highly hydrophilic materials were prepared by the phase inversion composition (PIC) method. After polymerization, nanoparticles with a small particle diameter (25-55 nm) and low polydispersity index were obtained. Parameters such as concentration of monomer, O/S weight ratio as well as the polymerization temperature were crucial to achieve a correct formation of these nanoparticles. Moreover, FT-IR studies showed the full conversion of the monomer to polyurethane and polyurea polymers. Likewise the involvement of the surfactant in the polymerization process through their nucleophilic groups to form the polymeric matrix was demonstrated. This could mean a first step in the development of biocompatible systems formulated with polyoxyethylene castor oil derivative surfactants. In addition, haemolysis and cell viability assays evidenced the good biocompatibility of KELP polyurethane and polyurea nanoparticles thus indicating the potential of these nanosystems as promising drug carriers. PMID:24275445

  9. On-line surfactant monitoring

    SciTech Connect

    Mullen, K.I.; Neal, E.E.; Soran, P.D.; Smith, B. [Los Alamos National Lab., NM (United States). Chemical Science and Technology Div.

    1995-04-01

    This group has developed a process to extract metal ions from dilute aqueous solutions. The process uses water soluble polymers to complex metal ions. The metal/polymer complex is concentrated by ultrafiltration and the metals are recovered by a pH adjustment that frees the metal ions. The metal ions pass through the ultrafiltration membrane and are recovered in a concentrated form suitable for reuse. Surfactants are present in one of the target waste streams. Surfactants foul the costly ultrafiltration membranes. It was necessary to remove the surfactants before processing the waste stream. This paper discusses an on-line device the authors fabricated to monitor the process stream to assure that all the surfactant had been removed. The device is inexpensive and sensitive to very low levels of surfactants.

  10. Characterizing alcohol and brine sensitivities of EOR surfactant systems

    SciTech Connect

    Foulser, R.W.S.; Goodyear, S.G.; Lee-Tuffnell C.D. [Winfrith Technology Centre, Dorchester (United Kingdom)

    1993-12-31

    Surfactant systems can increase oil recovery provided they produced near optimal phase behavior in a reservoir. To select the injectant to achieve this on mixing with reservoir fluids, requires a clear understanding of the effects of the system components on the phase behavior. New concepts are presented in this paper for quantifying the sensitivity of surfactant systems to salinity and cosurfactant concentration changes. The approach identifies the characteristic parameters as concentrations in the psudobrine phase. This enables combinations of parameters resulting in suboptimal, optimal and superoptimal phase behavior, defined in terms of microemulsion oil/water ratio, to be identified independent of secondary compositional effects such as the overall oil/water ratio. The approach has been applied to an experimental study of an anionic surfactant, alcohol cosurfactant system in which the salinity was varied over a wide range. This shows that the phase behavior of the system is much more sensitive to changes in conditions at low salinities than at higher salinities typical of sea water. The observed equivalence between salinity and cosurfactant concentration is explained using electrochemical theory, giving useful insight into the role of the cosurfactant concentration is explained using electrochemical theory, giving useful insight into the role of the cosurfactant and suggesting that the results have a general relevance to anionic surfactant/cosurfactant systems.

  11. Emulsions on demand using microsturctured devices

    NASA Astrophysics Data System (ADS)

    Mahe, Christian; Tranchant, Jean Francois; Tromeur, Melanie; Schwesinger, Norbert

    2003-01-01

    Emulsions are very common in the field of cosmetics. Unfortunately, most emulsions contain ineffective substances to increase the stability of the products for a long time. These stabilizers can cause some severe healthy problems in several cases. One possible solution is the production of emulsions on demand to prevent the use of stabilizers. Stable emulsion can be achieved if the diameters of the droplets of one solution surrounded by a second solution are smaller than 1?m. Microstructured devices are suited in principle to generate such droplet distributions. Basic task of the development was a micro emulsifier that can be integrated into cosmetic flacons and that can deliver emulsions on demand by pressing a human fingertip onto a part of the flacon. Standardized cosmetic flacons have been used as basic devices. They consist of two separate glass bottles for two different liquid phases and two mechanical pumps integrated in a multifunctional cap. Regarding the viscosity ranges of the two liquids different microemulsifier structures have been developed. External dimensions and connections of the device have been chosen in a way that allows an integration of the devices into the cap. The second design conists of several streaming paths in parallel that allow a reduction of the pressure drop. Furthermore, it consists of three structured silicon chips bonded together. Emulsions with a stability of about 15-30 min have been achieved without any stabilizers. External forces of less than 10N were sufficient to generate emulsions on demand.

  12. Interfacial shear rheology of protein-surfactant layers.

    PubMed

    Krägel, J; Derkatch, S R; Miller, R

    2008-12-01

    The shear rheology of adsorbed or spread layers at air/liquid and liquid/liquid phase boundaries is relevant in a wide range of technical applications such as mass transfer, monolayers, foaming, emulsification, oil recovery, or high speed coating. Interfacial shear rheological properties can provide important information about interactions and molecular structure in the interfacial layer. A variety of measuring techniques have been proposed in the literature to measure interfacial shear rheological properties and have been applied to pure protein or mixed protein adsorption layers at air/water or oil/water interfaces. Such systems play for example an important role as stabilizers in foams and emulsions. The aim of this contribution is to give a literature overview of interfacial shear rheological studies of pure protein and protein/surfactant mixtures at liquid interfaces measured with different techniques. Techniques which utilize the damping of waves, spectroscopic or AFM techniques and all micro-rheological techniques will not discuss here. PMID:18823871

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

    PubMed

    Kumbasar, Recep Ali

    2010-06-15

    The facilitated extraction of Cr(VI) through an emulsion liquid membrane (ELM) was investigated, using tributyl phosphate (TBP) as mobile carrier. The emulsion liquid membrane phase consists of kerosene as diluent, TBP as carrier, SPAN 80 as surfactant and (NH(4))(2)CO(3) solution as stripping phase. The extraction of chromium (VI) has been studied under various experimental conditions and have been determined the influences of surfactant concentration, extractant concentration, stripping solution base concentration, mixing speed, phase ratio, treatment ratio, chromium (VI) and HCl concentrations of the feed solution. It was observed that the extraction rate of Cr(VI) was affected by changes of surfactant concentration, extractant concentration, stripping solution base concentration, and mixing speed. The results obtained showed that by appropriate selection of the extraction and stability conditions, nearly all of chromium (VI) ions present in the feed solution were extracted within 2-4 min. The separation factors of chromium (VI) with respect to cobalt, nickel, copper, cadmium and zinc ions, based on initial feed concentration, have experimentally determined. PMID:20227829

  14. Emulsion package and method of mixing the emulsion

    SciTech Connect

    Snyder, R.G.; Brenneman, S.; Clancy, J.J.

    1984-08-28

    A coal tar emulsion driveway sealer is packaged in a sealed bag. The volume of sealer is less than half the capacity of the bag and the bag is substantially completely evacuated but for the sealer. The separated sealer is mixed by compressing the sides of the bag to induce turbulent flow of the paste and liquid for hydraulic mixing thereof. The sealer may be dispensed at a controlled rate without spattering by cutting a corner from the bag to provide a pour spout. The bag with the sealer may be contained in a carton. The bag membrane comprises an aluminum layer vapor deposited on polyester. Those two layers are sandwiched between layers of EVA copolymer.

  15. Surfactants and the skin.

    PubMed

    Dykes, P

    1998-02-01

    The skin surface is the interface between us, the organism, and the outside world. When we clean the skin we remove not only the bacteria, dirt and grease which have accumulated, but also part of our natural barrier - the stratum corneum. Corneocytes, both singly and in clumps, are released from the skin surface by the action of detergents and mechanical stimulation. So too are the lipids and proteins which make up the intercorneocyte region of the stratum corneum. The analysis of the types and amounts of materials released by a standard scrub procedure may prove useful in the selection of surfactants with particular properties. Changes in the physical properties of the skin occur after washing. For example, changes in skin surface pH and transepidermal water loss (a sensitive index of barrier function) are easily demonstrable. Excessive exposure to surfactants results in repeated damage to the stratum corneum which can in turn lead to an irritant dermatitis. Individual susceptibility to irritant dermatitis varies and this may be demonstrated using a simple patch test technique. This test is a way of potentially increasing the sensitivity of human based assays such as the soap chamber test by preselection of subjects. Alternatively it may be possible to use measurements of function such as transepidermal water loss or laser Doppler blood flow as an index of damage rather than conventional cutaneous irritancy. These approaches may help in the search for the ideal of a non-irritant cleanser. PMID:18505489

  16. Use of amine oxide surfactants for chemical flooding EOR (enhanced oil recovery)

    SciTech Connect

    Olsen, D.K.

    1989-11-01

    The use of amine oxides with and without alcohols as cosolvents, and in combination with other surfactants as mixed micellar formulations for enhanced oil recovery by surfactant flooding was investigated. Amine oxides are a salt-tolerant class of surfactants that produce low interfacial tension and can develop viscosity without the addition of polymers. These salt-tolerant formulations generate three-phase regions with hydrocarbons over a broad salinity range, develop moderate solubilization, and produce low interfacial tensions, however oil recovery from amine oxide-alcohol phase behavior optimized formulations was directly dependent upon the quantity of surfactant injected. The large pore volume and high concentration of surfactant required prohibits their economic use as the primary surfactant in chemical flooding EOR. Dimethylalkylamine oxides are useful as cosurfactants and viscosifiers in formulations with other surfactants for chemical flooding EOR but the use of ethoxylated and propoxylated amine oxides should be avoided due to the decomposition of these amine oxides under reservoir conditions. Phase behavior, phase inversion temperatures, and viscosity scans have been correlated with surfactant structures to provide a guide for amine oxide applications in chemical flooding. 36 refs., 5 figs., 6 tabs.

  17. Method for demulsification of bitumen emulsions

    SciTech Connect

    McCoy, D.R.; Entire, E.E.; Gipson, R.M.

    1984-07-03

    A process for recovering bitumen from oil-in-water (O/W) emulsions is disclosed wherein water soluble demulsifiers are used. These demulsifiers are polymers of specific quaternary ammonium monomers or co-polymers of these quaternary ammonium monomers wth other types of monomers wherein the greater portion of the co-polymer is comprised of the quaternary ammonium monomers. To resolve the bitumonous petroleum emulsions, the process is carried out between 25/sup 0/ and 160/sup 0/ C. wherein the demulsifier of the invention is contacted with the bituminous emulsion.

  18. Development of lamellar gel phase emulsion containing marigold oil (Calendula officinalis) as a potential modern wound dressing.

    PubMed

    Okuma, C H; Andrade, T A M; Caetano, G F; Finci, L I; Maciel, N R; Topan, J F; Cefali, L C; Polizello, A C M; Carlo, T; Rogerio, A P; Spadaro, A C C; Isaac, V L B; Frade, M A C; Rocha-Filho, P A

    2015-04-25

    Appropriate therapeutics for wound treatments can be achieved by studying the pathophysiology of tissue repair. Here we develop formulations of lamellar gel phase (LGP) emulsions containing marigold (Calendula officinalis) oil, evaluating their stability and activity on experimental wound healing in rats. LGP emulsions were developed and evaluated based on a phase ternary diagram to select the best LGP emulsion, having a good amount of anisotropic structure and stability. The selected LGP formulation was analyzed according to the intrinsic and accelerated physical stability at different temperatures. In addition, in vitro and in vivo studies were carried out on wound healing rats as a model. The LGP emulsion (15.0% marigold oil; 10.0% of blend surfactants and 75.0% of purified water [w/w/w]) demonstrated good stability and high viscosity, suggesting longer contact of the formulation with the wound. No cytotoxic activity (50-1000 ?g/mL) was observed in marigold oil. In the wound healing rat model, the LGP (15 mg/mL) showed an increase in the leukocyte recruitment to the wound at least on days 2 and 7, but reduced leukocyte recruitment after 14 and 21 days, as compared to the control. Additionally, collagen production was reduced in the LGP emulsion on days 2 and 7 and further accelerated the process of re-epithelialization of the wound itself. The methodology utilized in the present study has produced a potentially useful formulation for a stable LGP emulsion-containing marigold, which was able to improve the wound healing process. PMID:25684193

  19. The influence of various emulsifiers on the partitioning and antioxidant activity of hydroxybenzoic acids and their derivatives in oil-in-water emulsions

    Microsoft Academic Search

    Heiko Stöckmann; Karin Schwarz; Tuong Huynh-Ba

    2000-01-01

    The partitioning behavior of a series of hydroxybenzoic acids and their derivatives was determined in biphasic water-oil systems,\\u000a emulsifier solutions, and oil-in-water (O\\/W) emulsions. The effect of gradually decreasing polarity on partitioning behavior\\u000a and antioxidant efficiency in O\\/W emulsions was investigated by using gallic acid and its esters as antioxidants. Sodium dodecyl\\u000a sulfate (SDS), cetyltrimethylammonium bromide (CTAB), polyoxyethylene 20 cetyl

  20. Evaluation of the Stability of Concentrated Emulsions for Lemon Beverages Using Sequential Experimental Designs

    PubMed Central

    Almeida, Teresa Cristina Abreu; Larentis, Ariane Leites; Ferraz, Helen Conceição

    2015-01-01

    The study of the stability of concentrated oil-in-water emulsions is imperative to provide a scientific approach for an important problem in the beverage industry, contributing to abolish the empiricism still present nowadays. The use of these emulsions would directly imply a reduction of transportation costs between production and the sales points, where dilution takes place. The goal of this research was to evaluate the influence of the main components of a lemon emulsion on its stability, aiming to maximize the concentration of oil in the beverage and to correlate its physicochemical characteristics to product stability, allowing an increase of shelf life of the final product. For this purpose, analyses of surface and interface tension, electrokinetic potential, particle size and rheological properties of the emulsions were conducted. A 24-1 fractional factorial design was performed with the following variables: lemon oil/water ratio (30% to 50%), starch and Arabic gum concentrations (0% to 30%) and dioctyl sodium sulfosuccinate (0 mg/L to 100 mg/L), including an evaluation of the responses at the central conditions of each variable. Sequentially, a full design was prepared to evaluate the two most influential variables obtained in the first plan, in which concentration of starch and gum ranged from 0% to 20%, while concentration of lemon oil/water ratio was fixed at 50%, without dioctyl sodium sulfosuccinate. Concentrated emulsions with stability superior to 15 days were obtained with either starch or Arabic gum and 50% lemon oil. The most stable formulations presented viscosity over 100 cP and ratio between the surface tension of the emulsion and the mucilage of over 1. These two answers were selected, since they better represent the behavior of emulsions in terms of stability and could be used as tools for an initial selection of the most promising formulations. PMID:25793301

  1. Evaluation of the stability of concentrated emulsions for lemon beverages using sequential experimental designs.

    PubMed

    Almeida, Teresa Cristina Abreu; Larentis, Ariane Leites; Ferraz, Helen Conceição

    2015-01-01

    The study of the stability of concentrated oil-in-water emulsions is imperative to provide a scientific approach for an important problem in the beverage industry, contributing to abolish the empiricism still present nowadays. The use of these emulsions would directly imply a reduction of transportation costs between production and the sales points, where dilution takes place. The goal of this research was to evaluate the influence of the main components of a lemon emulsion on its stability, aiming to maximize the concentration of oil in the beverage and to correlate its physicochemical characteristics to product stability, allowing an increase of shelf life of the final product. For this purpose, analyses of surface and interface tension, electrokinetic potential, particle size and rheological properties of the emulsions were conducted. A 2(4-1) fractional factorial design was performed with the following variables: lemon oil/water ratio (30% to 50%), starch and Arabic gum concentrations (0% to 30%) and dioctyl sodium sulfosuccinate (0 mg/L to 100 mg/L), including an evaluation of the responses at the central conditions of each variable. Sequentially, a full design was prepared to evaluate the two most influential variables obtained in the first plan, in which concentration of starch and gum ranged from 0% to 20%, while concentration of lemon oil/water ratio was fixed at 50%, without dioctyl sodium sulfosuccinate. Concentrated emulsions with stability superior to 15 days were obtained with either starch or Arabic gum and 50% lemon oil. The most stable formulations presented viscosity over 100 cP and ratio between the surface tension of the emulsion and the mucilage of over 1. These two answers were selected, since they better represent the behavior of emulsions in terms of stability and could be used as tools for an initial selection of the most promising formulations. PMID:25793301

  2. Waterflood oil recovery with chromatographically balanced surfactant

    Microsoft Academic Search

    H. J. Hill; D. R. Thigpen

    1973-01-01

    A surfactant slug for tertiary oil recovery was designed to have a mobility less than the mobility of flowing oil and water in the reservoir, and the ratio of the concentrations of the surfactants to polymer thickener in the surfactant slug was adjusted so that the frontal advance rates were equal, (chromatographic balance). The surfactant slug contained sodium petroleum sulfonate

  3. Contact angle of surfactant solutions on precipitated surfactant surfaces. II. Effects of surfactant structure, presence of a subsaturated surfactant, pH, and counterion\\/surfactant ratio

    Microsoft Academic Search

    Piyada Balasuwatthi; Nimit Dechabumphen; Chintana Saiwan; John F. Scamehorn

    2004-01-01

    The contact angle of a saturated aqueous surfactant solution on the precipitate of that surfactant was measured by using the\\u000a sessile drop method. The sodium and calcium salts of alkyl sulfates (C12, C14, and C18) had advancing contact angles higher than those of alkyl trimethylammonium bromides (C14, C16, and C18). The measured advancing contact angles for several surfactant solutions did

  4. Adsorption at air-water and oil-water interfaces and self-assembly in aqueous solution of ethoxylated polysorbate nonionic surfactants.

    PubMed

    Penfold, Jeffrey; Thomas, Robert K; Li, Peixun X; Petkov, Jordan T; Tucker, Ian; Webster, John R P; Terry, Ann E

    2015-03-17

    The Tween nonionic surfactants are ethoxylated sorbitan esters, which have 20 ethylene oxide groups attached to the sorbitan headgroup and a single alkyl chain, lauryl, palmityl, stearyl, or oleyl. They are an important class of surfactants that are extensively used in emulsion and foam stabilization and in applications associated with foods, cosmetics and pharmaceuticals. A range of ethoxylated polysorbate surfactants, with differing degrees of ethoxylation from 3 to 50 ethylene oxide groups, have been synthesized and characterized by neutron reflection, small-angle neutron scattering, and surface tension. In conjunction with different alkyl chain groups, this provides the opportunity to modify their surface properties, their self-assembly in solution, and their interaction with macromolecules, such as proteins. Adsorption at the air-water and oil-water interfaces and solution self-assembly of the range of ethoxylated polysorbate surfactants synthesized are presented and discussed. PMID:25697294

  5. Synergistic behaviour of ZnO nanoparticles and gemini surfactants on the dynamic and equilibrium oil/water interfacial tension.

    PubMed

    Fereidooni Moghadam, Tahereh; Azizian, Saeid; Wettig, Shawn

    2015-03-21

    In this work the effect of ZnO nanoparticles on the interfacial behaviour of gemini surfactants (12-3-12 and 14-3-14) at the oil/water interface was investigated. Equilibrium and dynamic interfacial tension in the absence and presence of ZnO was measured and compared. The results show that the synergistic interactions between the surfactants and nanoparticles decrease the interfacial tension beyond that observed for each component, alone. Modelling of dynamic data with two different models indicates that the mechanism of surfactant migration (with and without ZnO) is mixed diffusion-kinetic-control. The Gibbs free energy of micellization and the Gibbs free energy of adsorption in the absence and presence of ZnO were calculated and compared. Finally the effect of addition of ZnO nanoparticles on emulsion stability was also examined. PMID:25687519

  6. Mineral-Surfactant Interactions for Minimum Reagents Precipitation and Adsorption for Improved Oil Recovery

    SciTech Connect

    P. Somasundaran

    2008-09-20

    Chemical EOR can be an effective method for increasing oil recovery and reducing the amount of produced water; however, reservoir fluids are chemically complex and may react adversely to the polymers and surfactants injected into the reservoir. While a major goal is to alter rock wettability and interfacial tension between oil and water, rock-fluid and fluid-fluid interactions must be understood and controlled to minimize reagent loss, maximize recovery and mitigate costly failures. The overall objective of this project was to elucidate the mechanisms of interactions between polymers/surfactants and the mineral surfaces responsible for determining the chemical loss due to adsorption and precipitation in EOR processes. The role of dissolved inorganic species that are dependent on the mineralogy is investigated with respect to their effects on adsorption. Adsorption, wettability and interfacial tension are studied with the aim to control chemical losses, the ultimate goal being to devise schemes to develop guidelines for surfactant and polymer selection in EOR. The adsorption behavior of mixed polymer/surfactant and surfactant/surfactant systems on typical reservoir minerals (quartz, alumina, calcite, dolomite, kaolinite, gypsum, pyrite, etc.) was correlated to their molecular structures, intermolecular interactions and the solution conditions such as pH and/or salinity. Predictive models as well as general guidelines for the use of polymer/surfactant surfactant/surfactant system in EOR have been developed The following tasks have been completed under the scope of the project: (1) Mineral characterization, in terms of SEM, BET, size, surface charge, and point zero charge. (2) Study of the interactions among typical reservoir minerals (quartz, alumina, calcite, dolomite, kaolinite, gypsum, pyrite, etc.) and surfactants and/or polymers in terms of adsorption properties that include both macroscopic (adsorption density, wettability) and microscopic (orientation/conformation of the adsorbed layers), as well as precipitation/abstraction characteristics. (3) Investigation of the role of dissolved species, especially multivalent ions, on interactions between reservoir minerals and surfactants and/or polymers leading to surfactant precipitation or activated adsorption. (4) Solution behavior tests--surface tension, interaction, ultra filtration, and other tests. (5) Surfactant-mineral interactions relative to adsorption, wettability, and electrophoresis. (6) Work on the effects of multivalent ions, pH, temperature, salinity, and mixing ratio on the adsorption. Developments of adsorption models to explain interactions between surfactants/polymers/minerals. (7) General guidelines for the use of certain surfactants, polymers and their mixtures in micelle flooding processes.

  7. Cationic surfactant-enhanced sorption and nonionic surfactant-enhanced solubilization of hydrophobic organic contaminants in groundwater. Final report, October 1993--April 1997

    SciTech Connect

    Hayworth, J.S.; Burris, D.R.

    1997-04-01

    This study was conducted to assess the feasibility of using surfactants to immobilize and recover contaminants from groundwater. Before such a remediation method can be employed in the field, a understanding of the complex transport, partitioning behavior, and interactions of the surfactants and in a dynamic groundwater system is required. Batch, column and box aquifer model experiments conducted to investigate the proposed remediation strategy. Also, numerical modeling tools were developed to predict the coupled cationic/nonionic/HOC transport behavior within a dynamic groundwater. Experimental results show that it is feasible to create a stationary cationic surfactant-enhanced in situ within an aquifer. The main criteria for sorbent zone development are a relatively high exchange capacity, a low carbon content, and a relatively homogeneous and permeable aquifer. Numerical simulation results indicate that mass-transfer limiting desorption of the cationic surfactant will likely occur within an enhanced sorbent zone.

  8. Phase and foam behavior study of CO{sub 2}-based foams at reservoir temperature and pressure. Final report, August 20, 1990--July 15, 1993

    SciTech Connect

    Whiting, W.B.; Lim, K.H.

    1993-10-01

    A major objective of the Enhanced Oil Recovery Program at Morgantown Energy Technology Center (METC) is to develop technologies based on CO{sub 2}, foams, emulsions, or other fluid dispersions that will alleviate viscous fingering and mobility control problems that severely limit the production of oil by miscible CO{sub 2}, flooding. In this project, data on the phase behavior of a model surfactant/water system were generated both to help in modeling work for phase behavior and dispersion morphologies and to provide an efficient experimental methodology for determination of these data from flow calorimetric measurements. The project consists of two separate but compatible subtasks, the results of which are described in detail in the two parts of the main body of this report.

  9. Sticky superhydrophobic filter paper developed by dip-coating of fluorinated waterborne epoxy emulsion

    NASA Astrophysics Data System (ADS)

    Huang, Xiangxuan; Wen, Xiufang; Cheng, Jiang; Yang, Zhuoru

    2012-09-01

    A superhydrophobic and superoleophilic coating for oil filter paper was synthesized based on waterborne bisphenol-A novolac epoxy emulsion. The benzoic acid (BA) and maleic anhydride (MA) were used as modification agents to give the epoxy resin hydrophilic groups (carboxyl) and Cdbnd C double bonds. And the fluorinated waterborne epoxy emulsion was prepared by free radical solution polymerization of dodecafluoroheptyl methacrylate (DFMA) monomer. The covalent bound low free energy fluorinated chains in the monomer reduce the surface energy of solidification polymers sufficiently to give rise to superhydrophobic behavior while conserving superoleophilicity. Surfaces prepared show a sticky property, which exhibits a static water contact angle of 152° for a 5 ?L droplet that does not slid off even when the sample is held upside down. This synthetic emulsion is simple and convenient as impregnating agent for filter paper, which can be considered as a suitable candidate for various substrates such as cotton textiles, E-glass and artificial fiber, and so on.

  10. Wax-incorporated emulsion gel beads of calcium pectinate for intragastric floating drug delivery.

    PubMed

    Sriamornsak, Pornsak; Asavapichayont, Panida; Nunthanid, Jurairat; Luangtana-Anan, Manee; Limmatvapirat, Sontaya; Piriyaprasarth, Suchada

    2008-01-01

    The purpose of this study was to prepare wax-incorporated pectin-based emulsion gel beads using a modified emulsion-gelation method. The waxes in pectin-olive oil mixtures containing a model drug, metronidazole, were hot-melted, homogenized and then extruded into calcium chloride solution. The beads formed were separated, washed with distilled water and dried for 12 h. The influence of various types and amounts of wax on floating and drug release behavior of emulsion gel beads of calcium pectinate was investigated. The drug-loaded gel beads were found to float on simulated gastric fluid if the sufficient amount of oil was used. Incorporation of wax into the emulsion gel beads affected the drug release. Water-soluble wax (i.e. polyethylene glycol) increased the drug release while other water-insoluble waxes (i.e. glyceryl monostearate, stearyl alcohol, carnauba wax, spermaceti wax and white wax) significantly retarded the drug release. Different waxes had a slight effect on the drug release. However, the increased amount of incorporated wax in the formulations significantly sustained the drug release while the beads remained floating. The results suggest that wax-incorporated emulsion gel beads could be used as a carrier for intragastric floating drug delivery. PMID:18459055

  11. Aging properties of Kodak type 101 emulsions

    NASA Technical Reports Server (NTRS)

    Dohne, B.; Feldman, U.; Neupert, W.

    1984-01-01

    Aging tests for several batches of Kodak type 101 emulsion show that storage conditions significantly influence how well the film will maintain its sensitometric properties, with sensitivity and density increasing to a maximum during this period. Any further aging may result in higher fog levels and sensitivity loss. It is noted that storage in an environment free of photographically active compounds allows film property optimization, and that film batches with different sensitivities age differently. Emulsions with maximum 1700-A sensitivity are 2.5 times faster than those at the low end of the sensitivity scale. These sensitive emulsions exhibit significantly accelerated changes in aging properties. Their use in space applications requires careful consideration of time and temperature profiles, encouraging the use of less sensitive emulsions when the controllability of these factors is limited.

  12. Multi-body coalescence in Pickering emulsions

    NASA Astrophysics Data System (ADS)

    Wu, Tong; Wang, Haitao; Jing, Benxin; Liu, Fang; Burns, Peter C.; Na, Chongzheng

    2015-01-01

    Particle-stabilized Pickering emulsions have shown unusual behaviours such as the formation of non-spherical droplets and the sudden halt of coalescence between individual droplets. Here we report another unusual behaviour of Pickering emulsions—the simultaneous coalescence of multiple droplets in a single event. Using latex particles, silica particles and carbon nanotubes as model stabilizers, we show that multi-body coalescence can occur in both water-in-oil and oil-in-water emulsions. The number of droplets involved in the nth coalscence event equals four times the corresponding number of the tetrahedral sequence in close packing. Furthermore, coalescence is promoted by repulsive latex and silica particles but inhibited by attractive carbon nanotubes. The revelation of multi-body coalescence is expected to help better understand Pickering emulsions in natural systems and improve their designs in engineering applications.

  13. Control of particle size by feed composition in the nanolatexes produced via monomer-starved semicontinuous emulsion copolymerization.

    PubMed

    Sajjadi, Shahriar

    2015-05-01

    Conventional batch and semicontinuous emulsion copolymerizations often produce large particles whose size cannot be easily correlated with the comonomer feed compositions, and are to some degree susceptible to composition drift. In contrast, we found that copolymer nanolatexes made via semicontinuous monomer-starved emulsion copolymerizations are featured with an average nanoparticle size being controlled by the feed composition, a high conversion achieved, and a high degree of particle composition uniformity. This was achieved because the rate of particle growth, during nucleation, was controlled by the rate of comonomer addition, and the copolymer composition, surfactant parking area on the particles, and nucleation efficiency determined by the comonomer feed composition. Two model systems, methyl methacrylate/styrene and vinyl acetate/butyl acrylate, with significant differences in water solubility were studied. Monomers were added to the aqueous solution of sodium dodecylsulfate and potassium persulfate at a low rate to achieve high instantaneous conversions. PMID:25617612

  14. Thermodynamic study of adsorption of homologous anionic and cationic surfactants.

    PubMed

    Góralczyk, D; Hac-Wydro, K; Wydro, P

    2004-09-01

    The simplified form of an integral adsorption isotherm based on Butler's equation was applied to describe surface behavior of a series of anionic (sodium alkylsulfonates) and cationic (alkylpyridinium halides) surfactants. This theory allows for the calculation of the free energy of adsorption (Delta G jk) value corresponding to the ability of a particular surfactant to undergo adsorption. The obtained results indicate that the value of Delta G jk depends linearly on the length of the hydrocarbon chain as well as on the kind and concentration of the added inorganic electrolyte. Moreover, it has been found that in the case of surfactants, which have the same length of the alkyl chain and adsorb from solutions containing the same inorganic electrolyte, the charge of hydrophilic group has insignificant influence on the value of Delta G jk. PMID:15276057

  15. Mixed micellization of gemini and conventional surfactant in aqueous solution: a lattice Monte Carlo simulation.

    PubMed

    Gharibi, Hussein; Khodadadi, Zahra; Mousavi-Khoshdel, S Morteza; Hashemianzadeh, S Majid; Javadian, Soheila

    2014-09-01

    In the current study, we have investigated the micellization of pure gemini surfactants and a mixture of gemini and conventional surfactants using a 3D lattice Monte Carlo simulation method. For the pure gemini surfactant system, the effects of tail length on CMC and aggregation number were studied, and the simulation results were found to be in excellent agreement with the experimental results. For a mixture of gemini and conventional surfactants, variations in the mixed CMC, interaction parameter ?, and excess Gibbs free energy G(E) with composition revealed synergism in micelle formation. Simulation results were compared to estimations made using regular solution theory to determine the applicability of this theory for non-ideal mixed surfactant systems. A large discrepancy was observed between the behavior of parameters such as the activity coefficients fi and the excess Gibbs free energy G(E) and the expected behavior of these parameters as predicted by regular solution theory. Therefore, we have used the modified version of regular solution theory. This three parameter model contains two parameters in addition to the interaction parameters: the size parameter, ?, which reflects differences in the size of components, and the packing parameter, P*, which reflects nonrandom mixing in mixed micelles. The proposed model provides a good description of the behavior of gemini and conventional surfactant mixtures. The results indicated that as the chain length of gemini surfactants in mixture is increased, the size parameter remains constant while the interaction and packing parameters increase. PMID:25218241

  16. Contact angle of surfactant solutions on precipitated surfactant surfaces

    Microsoft Academic Search

    Natthakeeraya Luangpirom; Nimit Dechabumphen; Chintana Saiwan; John F. Scamehorn

    2001-01-01

    In this study, the contact angle of a saturated aqueous surfactant solution onto the surface of a precipitate of that surfactant\\u000a is investigated. Those precipitates include fatty acids (C10, C12, C14, C16, and C18), sodium salts of fatty acids (C14, C16, and C18), calcium salts of fatty acids (C8, C10, C12, C14, C16, and C18). On virgin surfaces, free fatty

  17. Applied Statistics: Crude Oil Emulsions and Demulsifiers

    Microsoft Academic Search

    Michael K. Poindexter; Paul M. Lindemuth

    2004-01-01

    Water?in?crude oil emulsions are encountered at many oilfield production facilities. These emulsions are often inherently stable requiring the use of chemical treatment, heat, and residence time to effect resolution. The addition of chemical demulsifiers in small levels can greatly facilitate oil–water separation. Even with numerous demulsifier applications in place throughout the world, there still remains a great deal to understand

  18. Emulsifier for water-in-oil emulsions

    SciTech Connect

    Weete, J.D.; Griffith, G.L.

    1990-07-24

    This patent describes a water-in-oil emulsion. It comprises: a continuous oil phase, a discontinuous aqueous phase, and an emulsion stabilizing amount of a thermally altered lecithin composition which has been prepare by heating lecithin at a temperature in the range of from about 100{degrees}C, to about 250{degrees}C, for a period of time ranging from about 15 to about 480 minutes.

  19. Study of the Formation and Solution Properties of Worm-Like Micelles Formed Using Both N-Hexadecyl-N-Methylpiperidinium Bromide-Based Cationic Surfactant and Anionic Surfactant

    PubMed Central

    Yan, Zhihu; Dai, Caili; Feng, Haishun; Liu, Yifei; Wang, Shilu

    2014-01-01

    The viscoelastic properties of worm-like micelles formed by mixing the cationic surfactant N-hexadecyl-N-methylpiperidinium bromide (C16MDB) with the anionic surfactant sodium laurate (SL) in aqueous solutions were investigated using rheological measurements. The effects of sodium laurate and temperature on the worm-like micelles and the mechanism of the observed shear thinning phenomenon and pseudoplastic behavior were systematically investigated. Additionally, cryogenic transmission electron microscopy images further ascertained existence of entangled worm-like micelles. PMID:25296131

  20. Intravenous lipid emulsion in clinical toxicology

    PubMed Central

    2010-01-01

    Intravenous lipid emulsion is an established, effective treatment for local anesthetic-induced cardiovascular collapse. The predominant theory for its mechanism of action is that by creating an expanded, intravascular lipid phase, equilibria are established that drive the offending drug from target tissues into the newly formed 'lipid sink'. Based on this hypothesis, lipid emulsion has been considered a candidate for generic reversal of toxicity caused by overdose of any lipophilic drug. Recent case reports of successful resuscitation suggest the efficacy of lipid emulsion infusion for treating non-local anesthetic overdoses across a wide spectrum of drugs: beta blockers, calcium channel blockers, parasiticides, herbicides and several varieties of psychotropic agents. Lipid emulsion therapy is gaining acceptance in emergency rooms and other critical care settings as a possible treatment for lipophilic drug toxicity. While protocols exist for administration of lipid emulsion in the setting of local anesthetic toxicity, no optimal regimen has been established for treatment of acute non-local anesthetic poisonings. Future studies will shape the evolving recommendations for lipid emulsion in the setting of non-local anesthetic drug overdose. PMID:20923546

  1. Effect of surfactants on wetting of super-hydrophobic surfaces.

    PubMed

    Mohammadi, R; Wassink, J; Amirfazli, A

    2004-10-26

    The effect of surfactants on wetting behavior of super-hydrophobic surfaces was investigated. Super-hydrophobic surfaces were prepared of alkylketene dimer (AKD) by casting the AKD melt in a specially designed mold. Time-dependent studies were carried out, using the axisymmetric drop shape analysis method for contact angle measurement of pure water on AKD surfaces. The results show that both advancing and receding contact angles of water on the AKD surfaces increase over time ( approximately 3 days) and reach the values of about 164 and 147 degrees , respectively. The increase of contact angles is due to the development of a prickly structure on the surface (verified by scanning electron microscopy), which is responsible for its super-hydrophobicity. Aqueous solutions of sodium acetate, sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, and n-decanoyl-n-methylglucamine were used to investigate the wetting of AKD surfaces. Advancing and receding contact angles for various concentrations of different surfactant solutions were measured. The contact angle results were compared to those of a number of pure liquids with surface tensions similar to those of surfactant solutions. It was found that although the surface tensions of pure liquids and surfactant solutions at high concentrations are similar, the contact angles are very different. Furthermore, the usual behavior of super-hydrophobic surfaces that turn super-hydrophilic when the intrinsic contact angle of liquid on a smooth surface (of identical material) is below 90 degrees was not observed in the presence of surfactants. The difference in the results for pure liquids and surfactant solutions is explained using an adsorption hypothesis. PMID:15491199

  2. A New Emulsion Liquid Membrane Based on a Palm Oil for the Extraction of Heavy Metals

    PubMed Central

    Björkegren, Sanna; Fassihi Karimi, Rose; Martinelli, Anna; Jayakumar, Natesan Subramanian; Hashim, Mohd Ali

    2015-01-01

    The extraction efficiency of hexavalent chromium, Cr(VI), from water has been investigated using a vegetable oil based emulsion liquid membrane (ELM) technique. The main purpose of this study was to create a novel ELM formulation by choosing a more environmentally friendly and non-toxic diluent such as palm oil. The membrane phase so formulated includes the mobile carrier tri-n-octylmethylammonium chloride (TOMAC), to facilitate the metal transport, and the hydrophilic surfactant Tween 80 to facilitate the dispersion of the ELM phase in the aqueous solution. Span 80 is used as surfactant and butanol as co-surfactant. Our results demonstrate that this novel ELM formulation, using the vegetable palm oil as diluent, is useful for the removal of hexavalent chromium with an efficiency of over 99% and is thus competitive with the already existing, yet less environmentally friendly, ELM formulations. This result was achieved with an optimal concentration of 0.1 M NaOH as stripping agent and an external phase pH of 0.5. Different water qualities have also been investigated showing that the type of water (deionized, distilled, or tap water) does not significantly influence the extraction rate. PMID:25915191

  3. Apparent equilibration time required for surfactant-oil-water systems to emulsify into the morphology imposed by the formulation. Part 2: Effect of sec-butanol concentration and initial location.

    PubMed

    Alvarez, Gabriela; Antón, Raquel; Marfisi, Shirley; Márquez, Laura; Salager, Jean-Louis

    2004-06-22

    Winsor type I equilibrated surfactant-oil-water (SOW) systems produce o/w emulsions upon stirring. However, if the surfactant is initially dissolved in the oil phase, the attained type after inmediate emulsification is usually w/o. If the SOW system is partially equilibrated, it could result in a normal o/w emulsion, as if it were fully equilibrated. The minimum contact time for that to happen, the so-called apparent equilibration time tAPE, was previously shown (Langmuir 2002, 18, 607) to strongly depend on formulation, surfactant molecular weight, and oil viscosity. The present report shows that it depends on alcohol concentration and location in the unequilibrated system. PMID:15986647

  4. Solution rheology of polyelectrolytes and polyelectrolyte-surfactant systems

    NASA Astrophysics Data System (ADS)

    Plucktaveesak, Nopparat

    The fundamental understanding of polyelectrolytes in aqueous solutions is an important branch of polymer research. In this work, the rheological properties of polyelectrolytes and polyelectrolyte/surfactant systems are studied. Various synthetic poly electrolytes are chosen with varied hydrophobicity. We discuss the effects of adding various surfactants to aqueous solutions of poly(ethylene oxide)-b-poly(propylene oxide)- b-polyethylene oxide)-g-poly(acrylic acid) (PEO-PPO-PAA) in the first chapter. Thermogelation in aqueous solutions of PEO-PPO-PAA is due to micellization caused by aggregation of poly(propylene oxide) (PPO) blocks resulting from temperature-induced dehydration of PPO. When nonionic surfactants with hydrophilic-lipophilic balance (HLB) parameter exceeding 11 or Cn alkylsulfates; n-octyl (C8), n-decyl (C 10) and n-dodecyl (C12) sulfates are added, the gelation threshold temperature (Tgel) of 1.0wt% PEO-PPO-PAA in aqueous solutions increases. In contrast, when nonionic surfactants with HLB below 11 are added, the gelation temperature decreases. On the other hand, alkylsulfates with n = 16 or 18 and poly(ethylene oxide) (PEO) do not affect the Tgel. The results imply that both hydrophobicity and tail length of the added surfactant play important roles in the interaction of PEO-PPO-PAA micelles and the surfactant. In the second chapter, the solution behavior of alternating copolymers of maleic acid and hydrophobic monomer is studied. The alternating structure of monomers with two-carboxylic groups and hydrophobic monomers make these copolymers unique. Under appropriate conditions, these carboxylic groups dissociate leaving charges on the chain. The potentiometric titrations of copolymer solutions with added CaCl2 reveal two distinct dissociation processes corresponding to the dissociation of the two adjacent carboxylic acids. The viscosity data as a function of polymer concentration of poly(isobutylene-alt-sodium maleate), poly(styrene-alt-sodium maleate) and poly(diisobutylene- alt-sodium maleate) show the polyelectrolyte behavior as predicted. However, the viscosity as a function of concentration of sodium maleate based copolymers with 1-alkenes; 1-octene (C8), 1-decene (C10), 1-dodecene (C12) and 1-hexene (C14) exhibit an abnormal scaling power, which might be caused by aggregation of the alkene tails to form micelles. In the last chapter, we report the rheological properties of aqueous solutions of poly(acrylic acid) and oppositely charged surfactant, dodecyl trimethylammonium bromide (C12TAB). The solution viscosity decreases as surfactant is added, partly because the polyelectrolyte wraps around the surface of the spherical surfactant micelles, shortening the effective chain length. The effects of polymer molecular weight, polymer concentration, and polymer charge have been studied with no added salt. The results are compared with the predictions of a simple model based on the scaling theory for the viscosity of dilute and unentangled semidilute polyelectrolyte solutions in good solvent. This model takes into account two effects of added surfactant. The effective chain length of the polyelectrolyte is shortened when a significant fraction of the chain wraps around micelles. Another effect is the change of solution ionic strength resulting from surfactant addition that further lowers the viscosity. The parameters used in this model are independently determined, allowing the model to make a quantitative prediction of solution viscosity with no adjustable parameters. The model is also applied to predict the decrease in viscosity of various polyelectrolyte/oppositely charged surfactant systems reported in literature. The results are in good agreement with experimental data, proving that our model applies to all polyelectrolytes mixed with oppositely charged surfactants that form spherical micelles.

  5. Surfactant instabilities on thin films

    E-print Network

    Aessopos, Angelica

    2005-01-01

    The deposition of a surfactant drop over a thin liquid film may be accompanied by a fingering instability. In this work, we present experimental results which identify the critical parameters that govern the shape and ...

  6. SCREENING METHODS FOR SELECTION OF SURFACTANT FORMULATIONS FOR IOR FROM FRACTURED CARBONATE RESERVOIRS

    SciTech Connect

    William A. Goddard III; Yongchun Tang; Patrick Shuler; Mario Blanco; Yongfu Wu; Seung Soon Jang

    2005-07-01

    This topical report presents details of the laboratory work performed to complete Task 1 of this project; developing rapid screening methods to assess surfactant performance for IOR (Improved Oil Recovery) from fractured carbonate reservoirs. The desired outcome is to identify surfactant formulations that increase the rate and amount of aqueous phase imbibition into oil-rich, oil-wet carbonate reservoir rock. Changing the wettability from oil-wet to water-wet is one key to enhancing this water-phase imbibition process that in turn recovers additional oil from the matrix portion of a carbonate reservoir. The common laboratory test to evaluate candidate surfactant formulations is to measure directly the aqueous imbibition rate and oil recovery from small outcrop or reservoir cores, but this procedure typically requires several weeks. Two methods are presented here for the rapid screening of candidate surfactant formulations for their potential IOR performance in carbonate reservoirs. One promising surfactant screening protocol is based on the ability of a surfactant solution to remove aged crude oil that coats a clear calcite crystal (Iceland Spar). Good surfactant candidate solutions remove the most oil the quickest from the chips, plus change the apparent contact angle of the remaining oil droplets on the surface that thereby indicate increased water-wetting. The other fast surfactant screening method is based on the flotation behavior of powdered calcite in water. In this test protocol, first the calcite power is pre-treated to make the surface oil-wet. The next step is to add the pre-treated powder to a test tube and add a candidate aqueous surfactant formulation; the greater the percentage of the calcite that now sinks to the bottom rather than floats, the more effective the surfactant is in changing the solids to become now preferentially water-wet. Results from the screening test generally are consistent with surfactant performance reported in the literature.

  7. The structures of salicylate surfactants with long alkyl chains in non-aqueous media.

    PubMed

    Lee, Chern Leing; Dowding, Peter J; Doyle, Allyson R; Bakker, Katrina M; Lam, Su Shiung; Rogers, Sarah E; Routh, Alexander F

    2013-12-01

    The self-assembled structures formed by alkyl salicylate surfactants, as a function of metal headgroup counterion, in dodecane and toluene have been investigated. Results from optical microscopy are combined with small angle neutron scattering to show that moisture in the organic phase can have a dramatic effect on the observed structures. A simple acidic cation produces a cluster of surfactant chains irrespective of the oil type or presence of water. However, systems with an alkali metal counterion (potassium or sodium) result in cylindrical micelles in dry dodecane changing to lamellar structures in the wet case and fuzzy spheres in dry toluene changing to bidisperse emulsions with the presence of water. However, if magnesium or calcium counterions are used, this leads to different structures, depending on the oil type and the presence of moisture. PMID:24228896

  8. A novel sodium N-fatty acyl amino acid surfactant using silkworm pupae as stock material

    NASA Astrophysics Data System (ADS)

    Wu, Min-Hui; Wan, Liang-Ze; Zhang, Yu-Qing

    2014-03-01

    A novel sodium N-fatty acyl amino acid (SFAAA) surfactant was synthesized using pupa oil and pupa protein hydrolysates (PPH) from a waste product of the silk industry. The aliphatic acids from pupa oil were modified into N-fatty acyl chlorides by thionyl chloride (SOCl2). SFAAA was synthesized using acyl chlorides and PPH. GC-MS analysis showed fatty acids from pupa oil consist mainly of unsaturated linolenic and linoleic acids and saturated palmitic and stearic acids. SFAAA had a low critical micelle concentration, great efficiency in lowering surface tension and strong adsorption at an air/water interface. SFAAA had a high emulsifying power, as well as a high foaming power. The emulsifying power of PPH and SFAAA in an oil/water emulsion was better with ethyl acetate as the oil phase compared to n-hexane. The environment-friendly surfactant made entirely from silkworm pupae could promote sustainable development of the silk industry.

  9. Surfactant-enhanced alkaline flooding for light oil recovery. Annual report, 1992--1993

    SciTech Connect

    Wasan, D.T.

    1994-08-01

    In this report, the authors present the results of experimental and theoretical studies in surfactant-enhanced alkaline flooding for light oil recovery. The overall objective of this work 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 ultralow interfacial tension. In addition, the authors have (1) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, (2) investigated the mechanisms for spontaneous emulsification, (3) developed a technique to monitor low water content in oil, and (4) developed a technique to study water-in-oil emulsion film properties.

  10. A novel sodium N-fatty acyl amino acid surfactant using silkworm pupae as stock material.

    PubMed

    Wu, Min-Hui; Wan, Liang-Ze; Zhang, Yu-Qing

    2014-01-01

    A novel sodium N-fatty acyl amino acid (SFAAA) surfactant was synthesized using pupa oil and pupa protein hydrolysates (PPH) from a waste product of the silk industry. The aliphatic acids from pupa oil were modified into N-fatty acyl chlorides by thionyl chloride (SOCl2). SFAAA was synthesized using acyl chlorides and PPH. GC-MS analysis showed fatty acids from pupa oil consist mainly of unsaturated linolenic and linoleic acids and saturated palmitic and stearic acids. SFAAA had a low critical micelle concentration, great efficiency in lowering surface tension and strong adsorption at an air/water interface. SFAAA had a high emulsifying power, as well as a high foaming power. The emulsifying power of PPH and SFAAA in an oil/water emulsion was better with ethyl acetate as the oil phase compared to n-hexane. The environment-friendly surfactant made entirely from silkworm pupae could promote sustainable development of the silk industry. PMID:24651079

  11. Nonionic cleavable ortho ester surfactants

    Microsoft Academic Search

    Per-Erik Hellberg; Karin Bergström; Malin Juberg

    2000-01-01

    A new class of cleavable surfactants based on the ortho ester link is described. Ortho ester surfactants were synthesized\\u000a from a short-chain ortho ester, a fatty alcohol, and a poly(ethylene glycol) monomethyl ether. The triple functionality of\\u000a the ortho ester link results in a mixture of surface-active and nonsurface-active species. Structures were confirmed by 1H and 13C nuclear magnetic resonance.

  12. A method for the characterization of emulsions, thermogranulometry: application to water-in-crude oil emulsion.

    PubMed

    Clausse, D; Gomez, F; Dalmazzone, C; Noik, C

    2005-07-15

    Emulsions are used in a wide range of applications and industries. Their size distribution is an important parameter because it influences most of the emulsion properties of emulsions. Several techniques of characterization are used to determine the granulometric distribution of emulsions, but they are generally limited to dilute samples and are based on complex algorithms. We describe a method that allows characterization of the droplet size distribution of emulsions using thermal analysis (thermogranulometry). This method permits the use of very concentrated samples without any dilution or perturbation of the system. We first define our method by a thermodynamic and kinetic approach. We studied a real system, i.e., crude oil emulsions, which form very concentrated, viscous, and opaque emulsions with water. We present a correlation between the size of droplets and their freezing temperature, corresponding to our system. Then we compare the size distributions obtained by our method with those derived by direct microscopy observations. The results obtained show that thermogranulometry may be an interesting method of characterization of emulsions, even for concentrated systems. PMID:15925639

  13. Development of surfactant coacervation in aqueous solution.

    PubMed

    Wang, Meina; Wang, Yilin

    2014-10-28

    Coacervation is a phenomenon in which a colloidal dispersion separates into two immiscible liquid phases: a liquid rich in colloidal phase in equilibrium with another diluted liquid phase. Surfactant coacervation here refers to coacervation whose main components are surfactants with low molecular weights. Over the past two decades, surfactants have been greatly developed and studies on coacervation in systems of novel surfactants have been reported. This review summarizes the development of coacervation occurring in monomeric surfactants, one-head and two-tail surfactants, gemini surfactants and their mixtures. The effects of surfactant molecular structure and external conditions on critical conditions for coacervation, structures of precursors and coacervates, and their relationships are described. The effects of inorganic salts, alcohols and organic salts on surfactant coacervation are also reviewed. PMID:25144160

  14. Lipoplexes formed from sugar-based gemini surfactants undergo a lamellar-to-micellar phase transition at acidic pH. Evidence for a non-inverted membrane-destabilizing hexagonal phase of lipoplexes

    Microsoft Academic Search

    Luc Wasungu; Marc C. A. Stuart; Marco Scarzello; Jan B. F. N. Engberts; Dick Hoekstra

    2006-01-01

    The present study aims at a better understanding of the mechanism of transfection mediated by two sugar-based gemini surfactants GS1 and GS2. Previously, these gemini surfactants have been shown to be efficient gene vectors for transfection both in vitro and in vivo. Here, using Nile Red, a solvatochromic fluorescent probe, we investigated the phase behavior of these gemini surfactants in

  15. Differential scanning calorimetric study of nonionic surfactant mixtures with a room temperature ionic liquid, bmimBF4.

    PubMed

    Inoue, Tohru; Higuchi, Yuka; Misono, Takeshi

    2009-10-01

    The melting behavior of polyethyleneglycol dodecyl ethers (C(12)E(6), C(12)E(7), and C(12)E(8)) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)), was investigated by means of differential scanning calorimetry (DSC). The melting temperature as a function of the surfactant concentration, combined with the cmc curve and cloud point curve, provided phase diagrams for the surfactant/bmimBF(4) mixtures in solvent-rich region. The characteristic feature of the mixtures is an existence of the Krafft temperature which is usually not observed with aqueous solutions of nonionic surfactants. The heat of fusion as a function of the surfactant concentration provided the interaction energy between the surfactant and bmimBF(4). The interaction energy shows a linear dependence on the length of polyoxyethylene (POE) chain of the surfactants, which suggests that the solvation takes place around the POE chain. PMID:19501832

  16. Enzymatic degradation of SLN-effect of surfactant and surfactant mixtures.

    PubMed

    Olbrich, C; Müller, R H

    1999-03-25

    Solid lipid nanoparticles (SLN) show different degradation velocities by the lipolytic enzyme pancreatic lipase as a function of their composition (lipid matrix, stabilizing surfactant). In combination with pancreatic colipase a degradation assay has been developed for studying the degradation behavior. As a measure to follow the degradation the formed free fatty acids have been analyzed using an enzymatic test. In the studies SLN degradation showed dependencies in relation to the length of the fatty acid chains in the triglycerides and the surfactants used for SLN production. The longer the fatty acid chains in the glycerides, the slower the degradation. The influence of surfactants can be degradation accelerating (e.g. cholic acid sodium salt) or a hindering, degradation slowing down effect due to steric stabilization (e.g. Poloxamer 407). As a second steric stabilizer, Tween 80 has been used and the results showed a less pronounced effect on hindering the degradation process than for Poloxamer 407. This result seems to be correlated to the number of ethyleneoxide chains in the molecule. The longer the ethyleneoxide chains are in the molecule, the more hindered is the anchoring of the lipase/colipase complex and consequently the degradation of the SLN. The result can be used to adjust degradation of SLN and consequently drug release in a controlled way. PMID:10089289

  17. Relaxation of two colliding drops with trace amounts of insoluble surfactants

    NASA Astrophysics Data System (ADS)

    Vannozzi, Carolina

    2012-02-01

    Boundary integral simulations of the relaxation of two viscous drops in a equally viscous matrix, previously undergoing a flow-induced head-on collision in an extensional flow, showed that the acquired drop deformation, mostly localized in the thin film between the drops, induces a flow as the interface relaxes back to restore the drop original shape [1]. Under certain circumstances, this flow favors the coalescence of the drops. This phenomenon, the so-called relaxation-induced coalescence, is possible even in the case of collisions which would not lead to coalescence while the flow is active, i.e. those characterized by a drainage time exceeding the flow interaction time, influencing the final drop size distribution of blends/emulsions. The effect of trace amounts of insoluble surfactants on the aforementioned process is here examined in comparison with the clean interface system. As in the previous case relaxation-induced coalescence is still possible, but less likely, depending strongly on the surfactant diffusivity. Moreover, the addition of surfactants changes some of the basic features of the relaxation of surfactant free drops. [4pt] [1] C. Vannozzi, Relaxation and coalescence of two equal-sized viscous drops in a quiescent matrix, submitted to J Fluid Mech.

  18. Surfactant-enhanced alkaline flooding for light oil recovery. Final report 1994--1995

    SciTech Connect

    Wasan, D.T.

    1995-12-01

    In this report, the authors present the results of their experimental and theoretical studies in surfactant-enhanced alkaline flooding for light oil recovery. The overall objective of this work 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 ultralow interfacial tension. In addition, the authors have (1) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, (2) investigated the mechanisms for spontaneous emulsification, (3) developed a technique to monitor low water content in oil, and (4) developed a technique to study water-in-oil emulsion film properties, (5) investigated the effect of surfactant on the equilibrium and transient interfacial tension, (6) investigated the kinetics of oil removal from a silica surface, and (7) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, accounting for added surfactant. The results of the studies conducted during the course of this project are summarized.

  19. Surfactant-enhanced alkaline flooding for light oil recovery. Final report

    SciTech Connect

    Wasan, D.T.

    1996-05-01

    In this report, we present the results of our experimental and theoretical studies in surfactant-enhanced alkaline flooding for light oil recovery. The overall objective of this work 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 ultralow interfacial tension. In addition, we have (1) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, (2) investigated the mechanisms for spontaneous emulsification, (3) developed a technique to monitor low water content in oil and (4) developed a technique to study water-in-oil emulsion film properties, (5) investigated the effect of surfactant on the equilibrium and transient interfacial tension, (6) investigated the kinetics of oil removal from a silica surface, and (7) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, accounting for added surfactant. The results of the studies conducted during the course of this project are discussed.

  20. Liquid Fuel Emulsion Jet-in-Crossflow Penetration and Dispersion Under High Pressure Conditions

    NASA Astrophysics Data System (ADS)

    Gomez, Guillermo Andres

    The current work focuses on the jet-in-crossflow penetration and dispersion behavior of water-in-oil emulsions in a high pressure environment. Both fuel injection strategies of using a water-in-oil emulsion and a jet-in-crossflow have demonstrated unique benefits in improving gas turbine performance from an emissions and efficiency standpoint. A jet-in-crossflow is very practical for use in gas turbine engines, rocket propulsion, and aircraft engines since it utilizes already available crossflow air to atomize fuel. Injecting water into a combustion chamber in the form of a water-in-oil emulsion allows for pollutant emissions reduction while reducing efficiency loses that may result from using a separate water or steam injection circuit. Dispersion effects on oil droplets are expected, therefore investigating the distribution of both oil and water droplets in the crossflow is an objective in this work. Understanding the synchronization and injection behavior of the two strategies is of key interest due to their combined benefits. A water-to-oil ratio and an ambient pressure parameter are developed for emulsion jet-in-crossflow trajectories. To this end, a total of 24 emulsion jet-in-crossflow tests were performed with varying ambient pressures of 2-8 atm and momentum flux ratios of 50, 85, and 120. Sobel edge filtering was applied to each averaged image obtained from a high speed video of each test case. Averaged and filtered images were used to resolve top and bottom edges of the trajectory in addition to the overall peak intensity up to 40 mm downstream of the injection point. An optimized correlation was established and found to differ from literature based correlations obtained under atmospheric pressure conditions. Overall it was found that additional parameters were not necessary for the top edge and peak intensity correlations, but a need for a unique emulsion bottom edge and width trajectory correlation was recognized. In addition to investigating emulsion jet-in-crossflow trajectory correlations, a unique Dual Planar Laser Induced Fluorescence (Dual-PLIF) method was applied for the first time on emulsions at elevated pressure conditions. From the Dual-PLIF results, qualitative observations provided insight into the unique dispersion of oil and water concentrations within a cross-sectional plane down stream of the jet-in-crossflow injection.

  1. Phase diagrams of stoichiometric polyelectrolyte-surfactant complexes

    NASA Astrophysics Data System (ADS)

    Leonard, Michael J.

    When a water-soluble polyelectrolyte is combined with an oppositely-charged surfactant solution at a stoichiometric charge ratio, self-assembly into a highly ordered, water-insoluble complex can occur. These materials exhibit phase structures which are analogous to their pure surfactant components, and significant effort has been made in the past several decades to characterize, predict, and control the various morphologies observed in these systems. However, a truly comprehensive understanding of the phase behavior of these systems is lacking. The purpose of this project is to establish general phase diagrams for self-assembled, stoichiometric poly(acrylate-co-acrylamide)-cetyltrimethylammonium halide (PAAm-CTAX) complexes by studying phase structure as a function of ionic strength, salt type, polyelectrolyte charge density, temperature, and applied osmotic pressure with small-angle X-ray scattering (SAXS). By developing a deeper understanding of the phase behavior and energetics of such a model system, it is hoped that general trends can be extrapolated to other polyelectrolyte-surfactant systems, such as polysaccharide-surfactant systems, which may provide the means to template desired structures in nanoporous, biocompatible matrices. Materials such as these may be attractive targets for drug delivery and nanoscale separation applications.

  2. The ability of single-chain surfactants to emulsify an aqueous-based liquid crystal oscillates with odd-even parity of alkyl-chain length.

    PubMed

    Varghese, Nisha; Shetye, Gauri S; Yang, Sijie; Wilkens, Stephan; Smith, Robert P; Luk, Yan-Yeung

    2013-12-15

    The physical properties of many organic molecules often oscillate when the number of carbons in their aliphatic chains changes from odd to even. This odd-even effect for single-chain surfactants in solution is rarely observed. Here, we report the ability of single-chain surfactants to emulsify a class of non-amphiphilic organic salts, disodium cromoglycate (5'DSCG) oscillates as a function of the odd or even number of the aliphatic carbons. This system provides a water-in-oil-in-water emulsion, in which aqueous droplets of 5'DSCG in liquid crystal phases are coated with single-chain surfactants in a bulk carrying aqueous solution. For both surfactants of [Formula: see text] and CH3(CH2)nCOO(-)Na(+), the ability to emulsify 5'DSCG molecules in water is stronger for surfactants with an odd number of sp(3)-hybridized carbon atoms in the aliphatic chains than those with an even number. This observed odd-even effect is consistent with the notion that conventional micelles possess a core of randomly arranged surfactant hydrocarbon tails. However, this water-in-oil-in-water resembles a vesicle system in which the surfactants assemble in a highly ordered structure that separates two aqueous systems. These new self-assembled phases have potential application in the formulation and design of new organic soft materials. PMID:24144379

  3. Avalanches of rearrangements in quasi-2D emulsion hopper flow

    E-print Network

    Xia Hong; Kenneth W. Desmond; Dandan Chen; Eric R. Weeks

    2015-03-25

    We experimentally study the flow of a quasi-two-dimensional emulsion through a constricting hopper shape. Our area fractions range from 0.83 to 0.99, such that the droplets are always in contact with one another and are in many cases highly deformed. At the lowest flow rates, the droplets exit the hopper via intermittent avalanches. At the highest flow rates, the droplets exit continuously. The transition between these two types of behaviors is a fairly smooth function of the mean strain rate. The avalanches are characterized by a power law distribution of the time interval between droplets exiting the hopper, with long intervals between the avalanches. There is little or no dependence of the flow behavior on the area fraction of the system.

  4. Conductivity factor in the electrostatic coalescence of crude oil emulsions 

    E-print Network

    Nelson, James B

    1998-01-01

    vertically-oriented, cylindrical coalescer. The electrical conductivity of each phase of the water-in-oil emulsion was varied to determine their effects on the rate of coalescence. Both light and intermediate grades of crude oil emulsions were modified...

  5. 21 CFR 524.802 - Enrofloxacin, silver sulfadiazine emulsion.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 false Enrofloxacin, silver sulfadiazine emulsion. 524.802 Section 524...524.802 Enrofloxacin, silver sulfadiazine emulsion. (a) Specifications...mg) enrofloxacin and 10 mg silver sulfadiazine. (b) Sponsor . See No....

  6. 21 CFR 524.802 - Enrofloxacin, silver sulfadiazine emulsion.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false Enrofloxacin, silver sulfadiazine emulsion. 524.802 Section 524...524.802 Enrofloxacin, silver sulfadiazine emulsion. (a) Specifications...mg) enrofloxacin and 10 mg silver sulfadiazine. (b) Sponsor . See No....

  7. 21 CFR 524.802 - Enrofloxacin, silver sulfadiazine emulsion.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 false Enrofloxacin, silver sulfadiazine emulsion. 524.802 Section 524...524.802 Enrofloxacin, silver sulfadiazine emulsion. (a) Specifications...mg) enrofloxacin and 10 mg silver sulfadiazine. (b) Sponsor . See No....

  8. 21 CFR 524.802 - Enrofloxacin, silver sulfadiazine emulsion.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 false Enrofloxacin, silver sulfadiazine emulsion. 524.802 Section 524...524.802 Enrofloxacin, silver sulfadiazine emulsion. (a) Specifications...mg) enrofloxacin and 10 mg silver sulfadiazine. (b) Sponsor . See No....

  9. Stability of the aqueous suspensions of nanotubes in the presence of nonionic surfactant.

    PubMed

    Lisunova, Milana O; Lebovka, Nikolai I; Melezhyk, Olexander V; Boiko, Yurie P

    2006-07-15

    Stability of aqueous suspensions of multiwalled carbon nanotubes (MWNTs) and their percolation behavior are investigated. Nanotubes of aqueous suspensions show a strong tendency to aggregation and networking into electroconductive clusters. The percolation threshold of the electrical conductivity is rather low and of order phi approximately 0.01 (where phi is the volume fraction), which can be explained by the high aspect ratio of MWNTs. Strong influence of the nonionic surfactant Triton X-305 on the colloidal stability of aqueous suspensions of MWNTs is observed. Addition of surfactant exerts a stabilizing effect at surfactant concentration C(s) proportional to the weight concentration C of MWNTs, C(s) approximately C mol/dm3. The transient behavior of electrical conductivity in the aqueous suspensions is explained by fractal aggregation processes. The fractal dimension is shown to be sensitive to the surfactant concentration C(s). PMID:16600279

  10. Structural evolution and phase characterization of polyelectrolyte/surfactant complexes in aqueous solution

    NASA Astrophysics Data System (ADS)

    Nause, Richard G.; Hoagland, David A.; Strey, Helmut H.

    2003-03-01

    The self-assembly behavior of polyelectrolyte/surfactant complexes was examined in dilute aqueous solution. We have chosen to study the interaction of a model polyelectrolyte [sodium poly(styrene sulfonate)] with cetyltrimethylammonium chloride (CTAC), a cationic surfactant, at varying ionic strength. At a certain charge ratio, the polyelectrolyte/surfactant assembly will collapse into a highly-ordered, insoluble complex. It is the evolution of structure in these systems as a function of surfactant composition and ionic strength that is of particular interest. Soluble structural characterization was performed via small angle neutron scattering in deuterated water. Small angle X-ray scattering was used to follow the phase behavior of the solid complexes above the insolubility point. The transition from soluble to insoluble complex and the mechanism of collapse is of particular interest in this study.

  11. Self-setting particle-stabilized emulsion for hard-tissue engineering.

    PubMed

    Iwasaki, Yasuhiko; Takahata, Yusuke; Fujii, Syuji

    2015-02-01

    Injectable self-setting materials have recently attracted interest for use in minimally invasive medical treatments and tissue engineering. In particular, calcium phosphate cements (CPCs) offer certain specific advantages for the treatment of bone defects. Although the inner structures of set CPCs are important for the apposition and remodeling of new bone, there are still limitations to the design of cements with a well-controlled inner structure. In the present study, we explored self-setting CPCs that generate interconnected macroporous matrices using solid-particle-stabilized emulsion templates. ?-Tricalcium phosphate (?-TCP) and poly(ethylene phosphate) sodium salt-coated poly(D,L-lactide-co-glycolide) (PLGA) microparticles were mixed with castor oil and water to form an oil-in-water (o/w) emulsion. The ?-TCP and PLGA microparticles functioned as an effective particulate emulsifier by adsorption at the oil-water interface. The resulting emulsion spontaneously set in a humidified atmosphere at ambient temperature. The setting behaviors of different emulsions were characterized through X-ray diffraction analysis and compressive-strength measurements. The PLGA microparticles did not hinder the rate of hardening of the emulsions, and they improved the compressive strengths of the set cements. The PLGA particles incorporated within the set cements were hydrolytically degraded, and the degradation of the PLGA particles resulted in the formation of an interconnected pore structure in the set cement. Finally, mouse osteoblastic (MC3T3-E1) cells were cultivated on the set CPCs. The adherent MC3T3-E1 cells adopted a spindle shape, and significant cellular invasion into the set CPCs was observed after degradation of the PLGA microparticles. In conclusion, self-setting emulsions stabilized with ?-TCP and PLGA microparticles constitute a novel candidate material for bone regeneration. PMID:25534478

  12. High pressure-resistant nonincendive emulsion explosive

    DOEpatents

    Ruhe, Thomas C. (Duquesne, PA); Rao, Pilaka P. (Baghlingampalli, IN)

    1994-01-01

    An improved emulsion explosive composition including hollow microspheres/bulking agents having high density and high strength. The hollow microspheres/bulking agents have true particle densities of about 0.2 grams per cubic centimeter or greater and include glass, siliceous, ceramic and synthetic resin microspheres, expanded minerals, and mixtures thereof. The preferred weight percentage of hollow microspheres/bulking agents in the composition ranges from 3.0 to 10.0 A chlorinated paraffin oil, also present in the improved emulsion explosive composition, imparts a higher film strength to the oil phase in the emulsion. The emulsion is rendered nonincendive by the production of sodium chloride in situ via the decomposition of sodium nitrate, a chlorinated paraffin oil, and sodium perchlorate. The air-gap sensitivity is improved by the in situ formation of monomethylamine perchlorate from dissolved monomethylamine nitrate and sodium perchlorate. The emulsion explosive composition can withstand static pressures to 139 bars and dynamic pressure loads on the order of 567 bars.

  13. Testing of microbial demulsifiers with heavy crude emulsions

    Microsoft Academic Search

    M. A. Wilkinson; D. G. Cooper

    1985-01-01

    Summary It has already been demonstrated that model water-in-kerosene systems and toluene diluted heavy crude oil emulsions can be broken by microbial agents. In this studyN. amarae andR. rhodochrous are used on undiluted, water-in-heavy crude oil emulsions. The high viscosity of the undiluted emulsions severely limits the demulsifying ability of the bacteria towards these field emulsions.

  14. Adsorption of zwitterionic gemini surfactants at the air–water and solid–water interfaces

    Microsoft Academic Search

    V Seredyuk; E Alami; M Nydén; K Holmberg; A. V Peresypkin; F. M Menger

    2002-01-01

    In the present paper we report the adsorption behavior of a series of zwitterionic gemini surfactants, Cx–PO4?–(CH2)2–N+(CH3)2–Cy where x+y=22 and x?y, at the air–water and solid–water interfaces. The critical micelle concentration (CMC), was determined by du Nouy ring tensiometry and by steady state fluorescence. The surface excess concentration of zwitterionic gemini surfactants was calculated from the surface tension versus log

  15. Interfacial properties and foam stability effect of novel gemini-type surfactants in aqueous solutions

    Microsoft Academic Search

    Durga P. Acharya; José M. Gutiérrez; Kenji Aramaki; Ken-ichi Aratani; Hironobu Kunieda

    2005-01-01

    Static and dynamic surface tension and interfacial rheological behavior of a novel anionic gemini-type surfactant without a spacer group, sodium 2,3-didodecyl-1,2,3,4-butane tetracarboxylate (GS), were investigated. Very low values for critical micelle concentration (8.9×10?5 M) as well as equilibrium surface tension (22.7 mN?m?1) were observed for the aqueous solutions. Dynamic surface tension (DST) is very slow and less sensitive to the surfactant

  16. Cosolvent effects on drag reduction, rheological properties and micelle microstructures of cationic surfactants

    Microsoft Academic Search

    Ying Zhang; Judith Schmidt; Yeshayahu Talmon; Jacques L. Zakin

    2005-01-01

    Some quaternary cationic surfactants, when mixed with a counterion, are known to self-assemble into threadlike micelles in water. Such behavior causes drastic changes in rheological properties of even very dilute solutions, allowing them to be used as drag reducing agents (DRA) in turbulent pipe flow circulating systems, such as district cooling\\/heating systems. Surfactant self-assembly is a physicochemical phenomenon whose character

  17. Kinetics of Anionic Surfactant Anoxic Degradation 

    E-print Network

    Camacho, Julianna G.

    2010-07-14

    commonly present in personal cleansing products and detergents; anionic, nonionic, and amphoteric. The surfactant used in this study is an anionic surfactant. Anionic synthetic detergents may be classified into sulfates and sulfonates (Figure 1). R...

  18. Kinetics of Anionic Surfactant Anoxic Degradation

    E-print Network

    Camacho, Julianna G.

    2010-07-14

    commonly present in personal cleansing products and detergents; anionic, nonionic, and amphoteric. The surfactant used in this study is an anionic surfactant. Anionic synthetic detergents may be classified into sulfates and sulfonates (Figure 1). R...

  19. Combustion Study of Stabilized Water-in-Diesel Fuel Emulsion

    Microsoft Academic Search

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

    2009-01-01

    An experimental investigation has been carried out to produce a stable diesel\\/water emulsion fuel and use it in a diesel engine under different operating and design conditions. The emulsion stayed stable for up to 30% water in diesel for up to one week and 20% water in diesel for four weeks. The physical properties of the stable W\\/D emulsions in

  20. Mixed Micellization of Dimeric (Gemini) Surfactants and Conventional Surfactants

    Microsoft Academic Search

    R. G. Alargova; I. I. Kochijashky; M. L. Sierra; K. Kwetkat; R. Zana

    2001-01-01

    The aqueous solutions of mixtures of various conventional surfactants and dimeric anionic and cationic surfactants have been investigated by electrical conductivity, spectrofluorometry, and time-resolved fluorescence quenching to determine the critical micelle concentrations and the micelle aggregation numbers in these mixtures. The following systems have been investigated: 12-2-12\\/DTAB, 12-2-12\\/C12E6, 12-2-12\\/C12E8, 12-3-12\\/C12E8, Dim3\\/C12E8, and Dim4\\/C12E8 (12-2-12 and 12-3-12=dimethylene-1,2- and trimethylene-1,3-bis(dodecyldimethylammonium bromide), respectively;

  1. Dipalmitoylphosphatidylcholine is not the major surfactant phospholipid species in all mammals.

    PubMed

    Lang, Carol J; Postle, Anthony D; Orgeig, Sandra; Possmayer, Fred; Bernhard, Wolfgang; Panda, Amiya K; Jürgens, Klaus D; Milsom, William K; Nag, Kaushik; Daniels, Christopher B

    2005-11-01

    Pulmonary surfactant, a complex mixture of lipids and proteins, lowers the surface tension in terminal air spaces and is crucial for lung function. Within an animal species, surfactant composition can be influenced by development, disease, respiratory rate, and/or body temperature. Here, we analyzed the composition of surfactant in three heterothermic mammals (dunnart, bat, squirrel), displaying different torpor patterns, to determine: 1) whether increases in surfactant cholesterol (Chol) and phospholipid (PL) saturation occur during long-term torpor in squirrels, as in bats and dunnarts; 2) whether surfactant proteins change during torpor; and 3) whether PL molecular species (molsp) composition is altered. In addition, we analyzed the molsp composition of a further nine mammals (including placental/marsupial and hetero-/homeothermic contrasts) to determine whether phylogeny or thermal behavior determines molsp composition in mammals. We discovered that like bats and dunnarts, surfactant Chol increases during torpor in squirrels. However, changes in PL saturation during torpor may not be universal. Torpor was accompanied by a decrease in surfactant protein A in dunnarts and squirrels, but not in bats, whereas surfactant protein B did not change in any species. Phosphatidylcholine (PC)16:0/16:0 is highly variable between mammals and is not the major PL in the wombat, dunnart, shrew, or Tasmanian devil. An inverse relationship exists between PC16:0/16:0 and two of the major fluidizing components, PC16:0/16:1 and PC16:0/14:0. The PL molsp profile of an animal species is not determined by phylogeny or thermal behavior. We conclude that there is no single PL molsp composition that functions optimally in all mammals; rather, surfactant from each animal is unique and tailored to the biology of that animal. PMID:16037124

  2. Kinetic Release of Alkalinity from Particle-Containing Oil-in-Water Emulsions

    NASA Astrophysics Data System (ADS)

    Muller, K.; Chapra, S. C.; Ramsburg, A.

    2014-12-01

    Oil-in-water emulsions are typically employed during remediation to promote biotic reduction of contaminants. Emulsions, however, hold promise for encapsulated delivery of many types of active ingredients required for successful site remediation or long-term site stewardship. Our research is currently focused on using alkalinity-containing particles held within oil-in-water emulsions to sustain control of subsurface pH. Here we describe results from laboratory experiments and mathematical modeling conducted to quantify the kinetics associated with the emulsion delivery and alkalinity release process. Kinetically stable oil-in-water emulsions containing (~60 nmCaCO3 or ~100 nm MgO particles) were previously developed using soybean oil and Gum Arabic as a stabilizing agent. Batch and column experiments were employed to assess the accessibility and release of the alkalinity from the emulsion. Successive additions of HCl were used in batch systems to produce several pH responses (pH rebounds) that were subsequently modeled to elucidate release mechanisms and rates for varying emulsion compositions and particle types. Initial results suggest that a linear-driving-force model is generally able to capture the release behavior in the batch system when the temporally-constant, lumped mass-transfer coefficient is scaled by the fraction of particle mass remaining within the droplets. This result suggests that the rate limiting step in the release process may be the interphase transfer of reactive species at the oil-water interface. 1-d column experiments were also completed in order to quantify the extent and rate of alkalinity release from emulsion droplets retained in a sandy medium. Alkalinity release from the retained droplets treated a pH 4 influent water for 25-60 pore volumes (the duration depended on particle type and mass loading), and the cessation in treatment corresponded to exhaustion of the particle mass held within the oil. Column experiments were simulated using a transport code containing the linear-driving-force expression evaluated in the batch experiments. In these simulations the lumped mass transfer coefficient was fit and compared with values predicted using existing correlations for liquid-liquid and solid-liquid interfaces in porous media.

  3. A computer simulation and molecular-thermodynamic framework to model the micellization of ionic branched surfactants in aqueous solution

    E-print Network

    Lin, Shangchao

    2008-01-01

    Surfactants, or surface active agents, are chemicals exhibiting amphiphilic behavior toward a solvent. This amphiphilic character leads to increased activity at interfaces and to self-assembly into micellar aggregates ...

  4. Treatment of cocaine overdose with lipid emulsion.

    PubMed

    Jakkala-Saibaba, R; Morgan, P G; Morton, G L

    2011-12-01

    We describe the management and recovery of a 28-year-old man following a history of overdose by nasal inhalation of cocaine. The patient was presented in a comatose state suffering from seizures and marked cardiovascularly instability. Intravenous lipid emulsion was administered following initial resuscitation and tracheal intubation, as a means of treating persistent cardiac arrhythmias and profound hypotension. Following lipid emulsion therapy, the patient's life-threatening cardiovascular parameters rapidly improved and he recovered well without any side effects, thus being discharged within 2 days. PMID:22074030

  5. Surfactants in water-borne paints

    Microsoft Academic Search

    Ann-Charlotte Hellgren; Peter Weissenborn; Krister Holmberg

    1999-01-01

    The main uses of surfactants in water-borne coatings are discussed. Special attention is put on the use of surfactants in latex polymerization and in post-emulsification of binders, such as alkyd resins. The advantage of polymerizable surfactants as emulsifier is pointed out and the use of atomic force microscopy (AFM) to observe differences in film properties between formulations based on polymerizable

  6. Surfactant dependent morphology of polymeric capsules of perfluorooctyl bromide: influence of polymer adsorption at the dichloromethane-water interface.

    PubMed

    Pisani, Emilia; Fattal, Elias; Paris, Juliane; Ringard, Catherine; Rosilio, Véronique; Tsapis, Nicolas

    2008-10-01

    In a strategy to develop more stable ultrasound contrast agents (UCAs), we have designed a process to obtain nano/microcapsules with a single core of liquid perfluorocarbon within a biodegradable polymeric shell of homogeneous thickness. During the optimization of perfluorooctyl bromide (PFOB) encapsulation by solvent emulsion-evaporation, a marked influence of surfactants has been observed. While sodium cholate leads to spherical capsules of homogeneous thickness, sodium taurocholate induces to the formation of "acorn"-particles with one hemisphere of PFOB and another one of PLGA, and polyvinyl alcohol is responsible for the coexistence of both morphologies. Whereas the theoretical model proposed by Torza and Mason [J. Colloid Interface Sci. 33 (1970) 67] fails to predict the observed morphologies, microscopic observations of the evaporation and interfacial tension measurements provide an insight into the mechanism of formation of these structures. Most probably, there is a competition between PLGA and the surfactant stabilizing the emulsion at the dichloromethane-water interface. If PLGA is able to adsorb at the interface, the core-shell morphology is obtained, otherwise the acorn morphology is preferentially formed. When the surfactant rearrangement at the interface is long (>30 min), a coexistence of morphologies can be obtained. PMID:18674774

  7. Micro-emulsion-assisted synthesis of ZnS nanospheres and their photocatalytic activity

    SciTech Connect

    Li Yao; He Xiaoyan [Department of Chemistry, Northeast Normal University, Changchun 130024 (China); Cao Minhua [Department of Chemistry, Northeast Normal University, Changchun 130024 (China)], E-mail: caomh043@nenu.edu.cn

    2008-11-03

    ZnS nanospheres with rough surface were synthesized by using a micro-emulsion-assisted solvothemal process. The molar ratio of [water]/[surfactant] played an important role in controlling the size of the ZnS nanospheres. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), field emission-scanning electron microscope (FE-SEM), and selected area electron diffraction (SAED) were used for the characterization of the resulting ZnS nanospheres. A possible formation mechanism was proposed. These ZnS nanospheres exhibited a good photocatalytic activity for degradation of an aqueous p-nitrophenol solution and the total organic carbon (TOC) of the degradation product has also been investigated.

  8. Synthesis and characterization of exfoliated polystyrene/ZnAl layered double hydroxide nanocomposite via emulsion polymerization.

    PubMed

    Ding, Peng; Qu, Baojun

    2005-11-01

    Exfoliated polystyrene (PS)/ZnAl layered double hydroxide (LDH) nanocomposites have been synthesized via emulsion polymerization in the presence of N-lauroyl-glutamate surfactants and long-chain n-hexadecane. The samples were characterized using elemental analysis, Fourier transform infrared (FTIR) spectrum, X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The XRD and TEM results demonstrate that the exfoliated ZnAl-LDH layers of 50-70 nm width and about 1 nm thickness were well dispersed at molecular level in the PS matrix. And the completely exfoliated PS/LDH nanocomposites can be obtained even at the 10 wt% LDH loading. When the 50% weight loss was selected as a comparison point, the decomposition temperature of exfoliated PS/LDH sample with 5 wt% LDH was ca. 28 degrees C higher than that of pure PS. PMID:16165142

  9. Synthesis and characterization of cellulose whiskers/polymer nanocomposite dispersion by mini-emulsion polymerization.

    PubMed

    Ben Mabrouk, Ayman; Rei Vilar, Manuel; Magnin, Albert; Belgacem, Mohamed Naceur; Boufi, Sami

    2011-11-01

    Stable film-forming nanocomposite particles with diameters ranging from 120 to 300 nm, based on polybutylmethacrylate (PBMA) and cellulose whiskers in water dispersions, were successfully synthesized in one step through mini-emulsion polymerization. The nanocomposite dispersion with a solid content of 25 wt.% and up to 5 wt.% of nanofiller loading was prepared by in situ polymerization, in the presence of the whiskers using dodecylpyridinium chloride (DPC), as a cationic surfactant, and 2,2-azobis(isobutyronitrile) (AIBN), as initiator. The electrostatic interaction between the positively charged droplets and negatively charged whiskers ensured the anchoring of the nanofiller around the polymer particles. The ensuing dispersions were characterized by Dynamic Light Scattering (DLS), ?-Potential Measurements, and Field-Emission Scanning Electron Microscopy (FE-SEM). After the film formation process, the nanocomposite film exhibits a high transparency, denoting the good dispersion of the whiskers throughout the matrix. PMID:21851951

  10. Bilayer membranes in micro-fluidics: from gel emulsions to soft functional devices

    E-print Network

    Thutupalli, Shashi; Seemann, Ralf; 10.1039/C0SM00312C

    2010-01-01

    We outline a concept of self-assembled soft matter devices based on micro-fluidics, which use surfactant bilayer membranes as their main building blocks, arrested in geometric structures provided by top-down lithography. Membranes form spontaneously when suitable water-in-oil emulsions are forced into micro-fluidic channels at high dispersed-phase volume fractions. They turn out to be remarkably stable even when pumped through the micro-fluidic channel system. Their geometric arrangement is self-assembling, driven by interfacial energy and wetting forces. The ordered membrane arrays thus emerging can be loaded with amphiphilic functional molecules, ion channels, or just be used as they are, exploiting their peculiar physical properties. For wet electronic circuitry, the aqueous droplets then serve as the 'solder points'. Furthermore, the membranes can serve as well-controlled coupling media between chemical processes taking place in adjacent droplets. This is shown for the well-known Belousov-Zhabotinski reac...

  11. Fabrication of novel microstructures based on orientation-dependent adsorption of surfactant molecules in a TMAH solution

    NASA Astrophysics Data System (ADS)

    Pal, Prem; Sato, K.; Gosalvez, M. A.; Tang, B.; Hida, H.; Shikida, M.

    2011-01-01

    In this work, the orientation-dependent adsorption of surfactant molecules on the silicon surface during etching in surfactant-added tetramethylammonium hydroxide (TMAH) is investigated. Triton X-100 (C14H22O(C2H4O)n, n = 9-10) and 25 wt% TMAH are used as surfactant and main etchant, respectively. The crystallographic planes affected by the surfactant molecules are determined by analyzing the etching behavior of different mask patterns on Si{1 0 0} wafers and silicon hemispheres in pure and surfactant-added TMAH. Taken together, the shapes of the etched profiles and the analysis of the hemispherical etch rates confirm that thick and dense adsorbed surfactant layers are typically formed on both the exact and vicinal Si{1 1 0} surfaces. In addition, the results indicate that the adsorbed surfactant layer behaves as a permeable mask, partially slowing down the etch rate of the affected surface orientation/s and thus enforcing their appearance on the etching front. The peculiar etching properties of surfactant-added and surfactant-free TMAH are then utilized for the fabrication of advanced micromechanical structures with new shapes on Si{1 0 0} wafers and polydimethylsiloxane based on complex Si{1 0 0} molds.

  12. Surfactant-polymer interaction for improved oil recovery. Semi-annual report, September 1, 1996--March 1, 1997

    SciTech Connect

    NONE

    1997-12-31

    The goal of the proposed research is to use the interaction between a surfactant and a polymer for efficient displacement of tertiary oil by improving slug integrity, adsorption and mobility control. The focus of this proposal is to design an inexpensive surfactant-polymer mixture that can efficiently recover tertiary oil by avoiding surfactant slug degradation, high adsorption and viscous/heterogeneity fingering. The strategy of the proposed research is to use a scaled physical areal model to monitor surfactant-polymer slug movement in well-defined laboratory-scale surfactant-polymer floods. Suitable surfactant and polymer systems will be identified from phase behavior and coreflood experiments. Polymers and surfactant concentrations will be varied and the stability of the surfactant movement will be measured in the scaled physical areal model. Vertical and horizontal injection will be studied. The scaled model, fluids and all rock-fluid properties will be adequately characterized. Mechanistic simulations will be made to capture the mechanisms of fluid flow. This simulation will be used for process scale-up and optimization. The proposed research will supply experimental data and mechanistic principles for optimum surfactant-polymer slug design.

  13. Effects of diesel-water emulsion combustion on diesel engine NOx emissions. Final report, 1 January 1998--1 May 1999

    SciTech Connect

    Canfield, A.C.

    1999-05-01

    This study examines the effects of combusting a mixture of diesel fuel, water, and surfactant on the nitrogen oxides (NOx) emissions from a compression ignition diesel engine. Extensive previous research in the literature has attributed the observed reduction of nitrogen oxide emissions to a suppression of flame temperature due to quenching effects from the water, thereby reducing thermal NOx formation. The report highlights the relevant theory, operation, and design parameters of diesel internal combustion engines. Experimental procedures conducted using a Detroit Diesel 4-cylinder diesel engine are discussed. Results from testing diesel fuel with varying ratios of water balanced with a surfactant to stabilize the emulsion are presented and discussed. The data shows significant NOx emission reduction with up to 45 percent water, by volume, in the fuel. These results are correlated with thermodynamic first law and equilibrium combustion products analyses to estimate the adiabatic flame temperature of the standard fuel and fuel-water emulsion cases. Results indicate that thermal NOx is indeed reduced by quenching and flame temperature suppression, confirming reports in the literature. Recommendations are given for further studies, including improving the fuel-water emulsion and considerations for long-term testing.

  14. Dispersion and rheology of surfactant-mediated silver nanoparticle suspensions

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Nan; Huang, Chih-Ta; Tseng, Wenjea J.; Wei, Ming-Hsiung

    2010-11-01

    Polycrystalline silver (Ag) nanoparticles were dispersed in solvent mixtures consisting of 2-butoxyethyl acetate (BCA) and diethylene glycol monoethyl ether acetate (CA) in a BCA:CA weight ratio of 5:1. Three commercially available polymeric surfactants were used, and the gravitational sedimentation, agglomerate-size distribution, isothermal adsorption, and rheological behavior of the nanoparticle suspensions were examined. One of the surfactants (hereafter termed 9250) was found effective in stabilizing the Ag nanoparticle suspensions. Both the adsorption isotherm and the Fourier transform infrared spectroscopy revealed the preferential adsorption of the 9250 surfactant molecules on the nanoparticle surface, forming a Langmuir-type monolayer adsorption in the given solvents so that a steric stabilization was rendered. An optimal surfactant concentration of 5 wt.% (in terms of the solids weight) was determined experimentally. In addition, the Ag suspensions with a broad range of solids concentration (? = 1-16 vol.%) showed a shear-thinning flow character over a shear-rate range from 1 to 4000 s-1, revealing that an attractive interparticle interaction was operative. Relative viscosity (?r) of the nanoparticle suspensions deviated from the linearity when ? was greater than ˜10 vol.%; at which, the attractive potential began to dominate the interparticle interactions. This ?r-? dependence was compared with various existing models and the (viscosity) predictive capability of the models was discussed.

  15. Diarmed (adamantyl/alkyl) surfactants from nitrilotriacetic acid.

    PubMed

    Trillo, Juan V; Vázquez Tato, José; Jover, Aida; de Frutos, Santiago; Soto, Victor H; Galantini, Luciano; Meijide, Francisco

    2014-11-01

    The compounds presented here constitute a clear example of molecular biomimetics as their design is inspired on the structure and properties of natural phospholipids. Thus novel double-armed surfactants have been obtained in which nitrilotriacetic acid plays the role of glycerol in phospholipids. The hydrophobic arms are linked to the head group through amide bonds (which is also the case of sphingomyelin): (R1NHCOCH2)(R2NHCOCH2)NCH2CO2H (R1 being CH3(CH2)11, CH3(CH2)17, CH3(CH2)7CHCH(CH2)8, and adamantyl, and R2=adamantyl). The dependence of the surface tension with concentration shows the typical profile of surfactants since a breaking point, which corresponds to the critical aggregation concentration (cac), is observed in all cases. The cac of these diarmed derivatives are about 1-3 orders of magnitude lower than those of classical monoalkyl derivatives used as reference compounds. In contrast to conventional surfactants, reversed trends in cac values and molecular areas at the solution-air interface have been observed. This anomalous behavior is tied to the structure of the surfactants and suggests that long and flexible alkyl chains should self-coil previous to the aggregation or adsorption phenomena. Above cac all compounds form large aggregates, globular in shape, which tend to associate forming giant aggregates. PMID:25465758

  16. Spectroscopic and Interfacial Properties of Myoglobin/Surfactant Complexes

    PubMed Central

    Tofani, Luca; Feis, Alessandro; Snoke, Roy E.; Berti, Debora; Baglioni, Piero; Smulevich, Giulietta

    2004-01-01

    The complexes of horse myoglobin (Mb) with the anionic surfactant sodium dodecyl sulfate (SDS), and with the cationic surfactants cetyltrimethylammonium chloride (CTAC) and decyltrimethylammonium bromide (DeTAB), have been studied by a combination of surface tension measurements and optical spectroscopy, including heme absorption and aromatic amino acid fluorescence. SDS interacts in a monomeric form with Mb, which suggests the existence of a specific binding site for SDS, and induces the formation of a hexacoordinated Mb heme, possibly involving the distal histidine. Fluorescence spectra display an increase of tryptophan emission. Both effects point to an increased protein flexibility. SDS micelles induce both the appearance of two more heme species, one of which has the features of free heme, and protein unfolding. Mb/CTAC complexes display a very different behavior. CTAC monomers have no effect on the absorption spectra, and only a slight effect on the fluorescence spectra, whereas the formation of CTAC aggregates on the protein strongly affects both absorption and fluorescence. Mb/DeTAB complexes behave in a very similar way as Mb/CTAC complexes. The surface activity of the different Mb/surfactant complexes, as well as the interactions between the surfactants and Mb, are discussed on the basis of their structural properties. PMID:15298921

  17. Surfactant mediated passivation to achieve chemical mechanical polishing selectivity

    NASA Astrophysics Data System (ADS)

    Bu, Kyoung-Ho

    Chemical mechanical polishing (CMP) is an indispensable technique in the microelectronics industry to achieve planarization and patterning of metal and dielectric layers. Device fabrication using high density and small pattern size requires precise control of CMP slurry properties. In this study, the performance of a colloidal silica CMP slurry for silica/silicon nitride, which consists of the shallow trench isolation (STI) structures, was investigated. Factors determining material removal rate and surface finish were examined. It was found that electrostatic interactions can have significant effects on CMP performance. Emphasis was placed on selective removal of material. More than 10-fold increase in selectivity over conventional colloidal silica slurry was achieved with the addition of sodium dodecyl sulfate (SDS), an anionic surfactant. Adsorption characteristics of SDS on silica and silicon nitride were measured as a function of slurry pH and surfactant concentration. It was determined that the preferential adsorption of SDS on silicon nitride by electrostatic attraction results in the formation of a material-selective self-assembled passivation (boundary lubrication) layer leading to selective polishing. It was found that the adsorption density of surfactant plays a dominant role in determining selectivity. Accordingly, material-targeted boundary layer lubrication concept may be used to develop selective CMP polishing slurries. A theoretical approach based on density function theory was attempted to model various aspects of surfactant adsorption. Through this approach, it was possible to predict adsorption behavior and related thermodynamic properties to assist selection of passivating molecules.

  18. Phase equilibria of catanionic surfactant-water systems

    SciTech Connect

    Jokela, P.; Joensson, B.; Khan, A.

    1987-06-04

    In this work, the phase equilibria of binary amphiphilic-water systems are studied, where the amphiphilic molecule is composed of a cationic (A ) and an anionic (A surfactant in equimolar ratio, and the inorganic counterions are eliminated (catanionic surfactant). The catanionic compounds studied are dodecylammonium dodecanoate, dodecylammonium dodecyl sulfate, dodecyltrimethylammonium dodecyl sulfate, and dodecylethyldimethylammonium dodecyl sulfate. As all the ionic surfactants have approximately the same solubility in water, the electrostatic effects in the system can be neglected. Below 373 K, the catanionic surfactant-water systems show similar phase behavior as lecithin-water systems, where a lamellar phase is in equilibrium with almost pure water. In both cases, the swelling of the lamellae is assumed to be due to the hydration force interactions between the bilayers. However, due to the structure of the polar headgroup, the catanionic systems are easier to describe in theoretical model studies of hydration force than the zwitterionic phospholipid systems. The experimental results show that the strength of the hydration force is more dependent on the size of the polar headgroups than the specific chemical composition of them. Furthermore, no hydrophobic attraction could be observed between the bilayers. The results are also discussed in light of some main theories that are suggested for the repulsive hydration force and the attractive hydrophobic interaction.

  19. Effects of agitation in emulsion polymerization of n-butyl methacrylate and its copolymerization with N-methylol acrylamide

    NASA Astrophysics Data System (ADS)

    Krishnan, Sitaraman

    Effects of agitation in emulsion polymerization were investigated using a 2 dm3 stirred reactor and Rushton turbine agitators and a semi-batch mode of reaction. High-solids recipes giving monodisperse polymer particles with core-shell morphology were developed for monomer-starved, semi-batch emulsion copolymerization of n-butyl methacrylate (BMA) and N-methylol acrylamide (NMA). A larger agitator, or a higher agitation speed, resulted in higher particle concentration, more viscous latex, less water-soluble polymer, and higher mass of coagulum. Better incorporation of NMA in the polymer particles was because of greater particle-water interfacial area and more efficient macromixing in the reactor. A mechanism where the surface of the polymer particles is the most favorable site for copolymerization, is proposed for the incorporation of NMA. Nucleation of a greater number of particles at higher agitation intensity was a general observation for recipes with surfactant concentrations below the critical micelle concentration (cmc). Effects of agitation on the kinetics of emulsion polymerization of BMA were studied using reaction calorimetry. At a reaction temperature of 70°C, the molecular weight was higher at higher agitation speed, while at 50°C, the converse was true. The order of dependence of the mass of coagulum on the agitation speed depended on the surfactant coverage of the polymer particles: the variation was almost two-fold (1.2 to 2.3). The coagulum mass was related to surfactant coverage using results from the DLVO theory. The volume-surface average diameter of the monomer droplets in the emulsion scaled to the 1.6 power of agitation speed, and the droplet size distribution was log-normal. Thermal crosslinking of the copolymer particles and films was investigated, and the effect of carbon tetrabromide on the gel content of the copolymer films was studied experimentally and theoretically. The increase in the gel content as a function of time during thermal curing was studied at temperatures of 90°C, 120°C, and 150°C. The calculated time required for disentanglement of the polymer chains explained the observed induction periods for gel formation at 90°C and 120°C. Morphologies of copolymer particles and latex films were studied using transmission electron microscopy and atomic force microscopy. Unique surface features attributable to crosslinked shell and linear core of the copolymer particles, were observed by AFM.

  20. Propylene oxide-ethylene oxide block copolymers as demulsifiers for water-in-oil emulsions, II. Effects of temperature, salinity, pH -value, and solvents on the demulsification efficiency

    Microsoft Academic Search

    N. N. Zaki; M. E. Abdel-Raouf; A.-A. A. Abdel-Azim

    1996-01-01

    The effects of temperature, NaCl concentration (salinity),pH value, and solvents on the demulsification efficiency of propylene oxide (PO)-ethylene oxide (EO) block copolymers in the breaking of synthetic water-in-benzene emulsions stabilized by petroleum asphaltenes have been thoroughly investigated. The demulsification efficiency of the studied polymeric surfactants was found to increase with increasing temperature and decreasing salinity of the aqueous phase. A