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

    SciTech Connect

    Lebone T. Moeti; Ramanathan Sampath.

    1998-05-01

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

  5. Geranyl acetate emulsions: surfactant association structures and emulsion inversion.

    PubMed

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

    2009-08-01

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

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Viscosity of the oil-in-water Pickering emulsion stabilized by surfactant-polymer and nanoparticle-surfactant-polymer system

    NASA Astrophysics Data System (ADS)

    Sharma, Tushar; Kumar, G. Suresh; Chon, Bo Hyun; Sangwai, Jitendra S.

    2014-11-01

    Information on the viscosity of Pickering emulsion is required for their successful application in upstream oil and gas industry to understand their stability at extreme environment. In this work, a novel formulation of oil-in-water (o/w) Pickering emulsion stabilized using nanoparticle-surfactant-polymer (polyacrylamide) system as formulated in our earlier work (Sharma et al., Journal of Industrial and Engineering Chemistry, 2014) is investigated for rheological stability at high pressure and high temperature (HPHT) conditions using a controlled-strain rheometer. The nanoparticle (SiO2 and clay) concentration is varied from 1.0 to 5.0 wt%. The results are compared with the rheological behavior of simple o/w emulsion stabilized by surfactant-polymer system. Both the emulsions exhibit non-Newtonian shear thinning behavior. A positive shift in this behavior is observed for surfactant-polymer stabilized emulsion at high pressure conditions. Yield stress is observed to increase with pressure for surfactant-polymer emulsion. In addition, increase in temperature has an adverse effect on the viscosity of emulsion stabilized by surfactant-polymer system. In case of nanoparticle-surfactant-polymer stabilized o/w emulsion system, the viscosity and yield stress are predominantly constant for varying pressure and temperature conditions. The viscosity data for both o/w emulsion systems are fitted by the Herschel-Bulkley model and found to be satisfactory. In general, the study indicates that the Pickering emulsion stabilized by nanoparticle-surfactant-polymer system shows improved and stable rheological properties as compared to conventional emulsion stabilized by surfactant-polymer system indicating their successful application for HPHT environment in upstream oil and gas industry.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Structure of high internal phase aqueous-in-oil emulsions and related inverse micelle solutions. 4. Surfactant mixtures.

    PubMed

    Reynolds, Philip A; Gilbert, Elliot P; Henderson, Mark J; White, John W

    2009-09-10

    The effects of combinations of surfactants on the structure and stability of high internal phase water-in-hexadecane and saturated ammonium nitrate-in-hexadecane oil-based emulsions and oil-based inverse micellar solutions are reported. The combinations were 750, 1,200, and 1,700 molecular weight monodisperse and 450 and 1,000 molecular weight polydisperse polyisobutylene acid amides, and sorbitan monooleate. The samples made from mixtures have qualitatively similar nanostructures to emulsions made from single surfactants. Again, for the emulsions, micrometer-scale aqueous droplets are dispersed in a continuous oil phase, which contains inverse spherical micelles composed of surfactant, hexadecane, and water. In quantitative terms, lower average surfactant molecular weight, lower ammonium nitrate content, and lower surfactant content increased the swelling of micelles, their water content, and the tendency of the emulsion to be unstable and form a sponge phase. This instability also allows micelle plasticity such that their geometry and content in mixed surfactant systems are not simply predictable by interpolation from single surfactant systems. An example was found of a mixed micelle 3 times larger than either single component micelle. The observed behavior suggests that mixing surfactant molecules of very different molecular weights destabilizes the emulsions, while mixing surfactants close in molecular weight has the opposite effect. The synergistic effects of surfactant molecular weight polydispersity and binary mixing are most marked for 1:1 molecular mixtures of surfactant. PMID:19681585

  18. 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

  19. Stabilization of emulsions using polymeric surfactants based on inulin.

    PubMed

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

    2004-05-20

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

  20. Perfluoroalklylated phospholipids as surfactants and co-surfactants forinjectable fluorocarbon emulsions.

    PubMed

    Santaella, C; Vierling, P; Riess, J G

    1992-01-01

    Highly fluorinated phospholipids were investigated as sole surfactant, and as co-surfactant with egg yolk phospholipids (EYP), in the formulation of 50% and 100% w/v perfluorodecalin emulsions. The surfactant's capability to stabilize such emulsions improves with the length of the perfluoroalklylated tail and with the increase of its relative weight in the hydrophobic chain. As sole surfactant, 2, which has the longest fluorinated tail has the highest efficacy. As co-surfactant with EYP, a strong stabilizing effect is found when the total hydrophobic chain length is adjusted to the EYP membrane's thickness, which is the case of 1. Dispersions of the F-phospholipids do not modify cell growth and viability and show no hemolytic activity on human red blood cells at concentrations in the 60-100g/L range. Acute toxicity tests in mice indicate - i.v. DL50 greater than 2.75 g/Kg body wt. PMID:1391518

  1. 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

  2. O/W emulsions stabilised by both low molecular weight surfactants and colloidal particles: The effect of surfactant type and concentration.

    PubMed

    Pichot, R; Spyropoulos, F; Norton, I T

    2010-12-01

    The stability against coalescence of O/W emulsions in the presence of both surfactants and colloidal particles was investigated. In particular the effect of the surfactant type and concentration in these emulsifier mixtures on the O/W emulsions' stability was studied. Two types of surfactants were selected; those that have the ability to stabilise O/W emulsions on their own (O/W surfactants) and those that cannot (W/O surfactants). Tween 60 and Sodium Caseinate were selected as the O/W surfactants and lecithin as the W/O surfactant. Oil-in-water emulsions prepared with both particles and any of the three surfactants were stable against coalescence but, depending on the type of surfactant, the behaviour of the systems was found to depend on surfactant concentration. The droplet sizes of emulsions stabilised by mixed emulsifier systems containing low concentrations of O/W surfactants (Tween 60 or Sodium Caseinate) were smaller than those solely stabilised by either the surfactant or particles alone. At intermediate O/W surfactants concentrations, the droplet sizes of the emulsions increased. Further increases in the O/W surfactants' concentration, resulted in the complete removal of particles from the interface with the system now behaving as a surfactant-only stabilised emulsion. The behaviour of emulsions stabilised by emulsifier mixtures containing W/O surfactants was not dependent on the concentration of surfactant: no removal of particles was observed. PMID:20817195

  3. Compositional ripening of particle- and surfactant-stabilised emulsions: a comparison.

    PubMed

    Binks, Bernard P; Fletcher, Paul D I; Holt, Benjamin L; Kuc, Olivia; Beaussoubre, Pascal; Wong, Kenneth

    2010-03-01

    When beta-ionone-in-water emulsions are mixed with squalane-in-water emulsions, the slightly water-soluble, mobile beta-ionone undergoes mass transfer to the drops of highly water-insoluble, immobile oil squalane. We have investigated this compositional ripening process for emulsions stabilised either by particles or by surfactant molecules. For particle-stabilised emulsions, the swelling of the squalane-containing drops triggers droplet coalescence which causes the final swollen droplet radius to be proportional to the swelling ratio to the power of 1. Surfactant-stabilised emulsions swell without coalescence which causes the final droplet radius to be proportional to the swelling ratio to the power 1/3. Addition of excess, non-adsorbed particles to the particle-stabilised emulsions suppresses the swelling-triggered coalescence and causes a switchover from particle to surfactant behaviour. PMID:20165771

  4. Hierarchical polymerized high internal phase emulsions synthesized from surfactant-stabilized emulsion templates.

    PubMed

    Wong, Ling L C; Villafranca, Pedro M Baiz; Menner, Angelika; Bismarck, Alexander

    2013-05-21

    In building construction, structural elements, such as lattice girders, are positioned specifically to support the mainframe of a building. This arrangement provides additional structural hierarchy, facilitating the transfer of load to its foundation while keeping the building weight down. We applied the same concept when synthesizing hierarchical open-celled macroporous polymers from high internal phase emulsion (HIPE) templates stabilized by varying concentrations of a polymeric non-ionic surfactant from 0.75 to 20 w/vol %. These hierarchical poly(merized)HIPEs have multimodally distributed pores, which are efficiently arranged to enhance the load transfer mechanism in the polymer foam. As a result, hierarchical polyHIPEs produced from HIPEs stabilized by 5 vol % surfactant showed a 93% improvement in Young's moduli compared to conventional polyHIPEs produced from HIPEs stabilized by 20 vol % of surfactant with the same porosity of 84%. The finite element method (FEM) was used to determine the effect of pore hierarchy on the mechanical performance of porous polymers under small periodic compressions. Results from the FEM showed a clear improvement in Young's moduli for simulated hierarchical porous geometries. This methodology could be further adapted as a predictive tool to determine the influence of hierarchy on the mechanical properties of a range of porous materials. PMID:23617331

  5. Effective Surfactants Blend Concentration Determination for O/W Emulsion Stabilization by Two Nonionic Surfactants by Simple Linear Regression

    PubMed Central

    Hassan, A. K.

    2015-01-01

    In this work, O/W emulsion sets were prepared by using different concentrations of two nonionic surfactants. The two surfactants, tween 80(HLB=15.0) and span 80(HLB=4.3) were used in a fixed proportions equal to 0.55:0.45 respectively. HLB value of the surfactants blends were fixed at 10.185. The surfactants blend concentration is starting from 3% up to 19%. For each O/W emulsion set the conductivity was measured at room temperature (25±2°), 40, 50, 60, 70 and 80°. Applying the simple linear regression least squares method statistical analysis to the temperature-conductivity obtained data determines the effective surfactants blend concentration required for preparing the most stable O/W emulsion. These results were confirmed by applying the physical stability centrifugation testing and the phase inversion temperature range measurements. The results indicated that, the relation which represents the most stable O/W emulsion has the strongest direct linear relationship between temperature and conductivity. This relationship is linear up to 80°. This work proves that, the most stable O/W emulsion is determined via the determination of the maximum R² value by applying of the simple linear regression least squares method to the temperature–conductivity obtained data up to 80°, in addition to, the true maximum slope is represented by the equation which has the maximum R² value. Because the conditions would be changed in a more complex formulation, the method of the determination of the effective surfactants blend concentration was verified by applying it for more complex formulations of 2% O/W miconazole nitrate cream and the results indicate its reproducibility. PMID:26664063

  6. Emulsion electrospinning of polycaprolactone: influence of surfactant type towards the scaffold properties.

    PubMed

    Hu, Jue; Prabhakaran, Molamma P; Ding, Xin; Ramakrishna, Seeram

    2015-01-01

    Producing uniform nanofibers in high quality by electrospinning remains a huge challenge, especially using low concentrated polymer solutions. However, emulsion electrospinning assists to produce nanofibers from less concentrated polymer solutions compared to the traditional electrospinning process. The influence of individual surfactants towards the morphology of the emulsion electrospun poly (ɛ-caprolactone)/bovine serum albumin (PCL/BSA) nanofibers were investigated by using (i) non-ionic surfactant sorbitane monooleate (Span80); (ii) anionic sodium dodecyl sulfate (SDS); and (iii) cationic benzyltriethylammonium chloride, and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer Pluronic F108 of different concentrations. The morphology, along with the chemical and mechanical properties of the fibers, was evaluated by field emission scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, differential scanning calorimetry, water contact angle, and tensile tester. With the addition of surfactants, the electrospinnability of dilute PCL solution was enhanced, with either branched or uniform fibers were obtained. Electrospinning of an emulsion containing 0.4% (w/v) SDS produced the smallest and the most uniform nanofibers (167 ± 39 nm), which was attributed to the high conductivity of the solution. Analysis revealed that the emulsion electrospun nanofibers containing different surfactants and surfactant concentrations differ in fiber morphology and mechanical properties. Results suggest that surfactants have the ability to modulate the fiber morphology via electrostatic and hydrogen bonding, depending on their chemical structure. PMID:25427625

  7. 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.

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

    PubMed

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

    2011-07-28

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

  9. Ability of surfactant headgroup size to alter lipid and antioxidant oxidation in oil-in-water emulsions.

    PubMed

    Silvestre, M P; Chaiyasit, W; Brannan, R G; McClements, D J; Decker, E A

    2000-06-01

    Oxidation of oil-in-water emulsion droplets is influenced by the properties of the interfacial membrane surrounding the lipid core. To evaluate how surfactant headgroup size influences lipid oxidation rates, emulsions were prepared with polyoxyethylene 10 stearyl ether (Brij 76) or polyoxyethylene 100 stearyl ether (Brij 700), which are structurally identical except for their hydrophilic headgroups, with Brij 700 containing 10 times more polyoxyethylene groups than Brij 76. Fe(2+)-promoted decomposition of cumene hydroperoxide was lower in Brij 700-stabilized than in Brij 76-stabilized hexadecane emulsions. Fe(2+)-promoted alpha-tocopherol oxidation rates were similar in hexadecane emulsion regardless of surfactant type. Brij 700 decreased production of hexanal from methyl linoleate and the formation of lipid peroxides and propanal from salmon oil compared to emulsions stabilized by Brij 76. These results indicate that emulsion droplet interfacial thickness could be an important determinant in the oxidative stability of food emulsions. PMID:10888498

  10. 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-ε-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

  11. 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

  12. Interfacial adsorption and surfactant release characteristics of magnetically functionalized halloysite nanotubes for responsive emulsions.

    PubMed

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

    2016-02-01

    Magnetically responsive oil-in-water emulsions are effectively stabilized by a halloysite nanotube supported superparamagnetic iron oxide nanoparticle system. The attachment of the magnetically functionalized halloysite nanotubes at the oil-water interface imparts magnetic responsiveness to the emulsion and provides a steric barrier to droplet coalescence leading to emulsions that are stabilized for extended periods. Interfacial structure characterization by cryogenic scanning electron microscopy reveals that the nanotubes attach at the oil-water interface in a side on-orientation. The tubular structure of the nanotubes is exploited for the encapsulation and release of surfactant species that are typical of oil spill dispersants such as dioctyl sulfosuccinate sodium salt and polyoxyethylene (20) sorbitan monooleate. The magnetically responsive halloysite nanotubes anchor to the oil-water interface stabilizing the interface and releasing the surfactants resulting in reduction in the oil-water interfacial tension. The synergistic adsorption of the nanotubes and the released surfactants at the oil-water interface results in oil emulsification into very small droplets (less than 20μm). The synergy of the unique nanotubular morphology and interfacial activity of halloysite with the magnetic properties of iron oxide nanoparticles has potential applications in oil spill dispersion, magnetic mobilization and detection using magnetic fields. PMID:26555959

  13. Ability of surfactant micelles to alter the partitioning of phenolic antioxidants in oil-in-water emulsions.

    PubMed

    Richards, Mark P; Chaiyasit, Wilailuk; McClements, D Julian; Decker, Eric A

    2002-02-27

    In oil-in-water emulsions, the physical location of antioxidants can be an important determinant in their activity. Surfactants can potentially influence the physical location of antioxidants in oil-in-water emulsions by causing solubilization of lipid-soluble antioxidants into the aqueous phase. Excess Brij micelles in an oil-in-water emulsion were found to increase the partitioning of phenolics into the continuous phase with polar antioxidants (propyl gallate) partitioning more than nonpolar antioxidants (butylated hydroxyltoluene). Solubilization of propyl gallate was rapid coming to equilibrium in less than 5 min. Increasing surfactant micelle concentrations from 0.3 to 2.8% increased the solubilization of propyl gallate by 2.3-fold. Solubilization of phenolic antioxidants into the aqueous phase by Brij micelles did not alter the oxidative stability of salmon oil-in-water emulsions, suggesting that surfactant micelles influenced oxidation rates by mechanisms other than antioxidant solubilization. PMID:11853513

  14. Effect of surfactant phase behavior on emulsification.

    PubMed

    Kaizu, Kazuhiro; Alexandridis, Paschalis

    2016-03-15

    In order to improve our understanding of the effects that the equilibrium phase behavior and structure of amphiphiles have on the emulsification process and the properties of emulsions stabilized by these amphiphiles, we have exploited the known phase behavior of polyoxyethylene-polyoxypropylene-polyoxyethylene (POE-POP-POE) amphiphilic block copolymers (Pluronics) in the presence of two immiscible solvents. Specifically, we considered ternary systems consisting of Pluronic F38, L64, P84, P104, or L121 with water and p-xylene which exhibit a very rich phase behavior, including a variety of water-continuous and oil-continuous lyotropic liquid crystalline (LLC) phases. We prepared emulsions having the same (final) compositions but through different emulsification paths, and evaluated the emulsions on the basis of homogeneity and droplet size. We found finer and more homogenous emulsions to result when O/lamellar gel structures (as revealed by small-angle X-ray scattering) were formed during the emulsification process, or when the emulsification path traversed the lamellar LLC phase. This can be attributed to the favorable properties of the lamellar structure: high oil solubilization capacity with concurrent facile dispersibility in water, relatively low interfacial tension, and relatively low viscosity. The findings reported here are relevant to the preparation of emulsions for diverse applications such as skin-care products, pharmaceuticals, food products, coatings, inks, agrochemicals, oil dispersants, and nanomaterials synthesis. PMID:26724700

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

    NASA Astrophysics Data System (ADS)

    Skartlien, R.; Sollum, E.; Schumann, H.

    2013-11-01

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

  16. Nonaqueous Dispersion Formed by an Emulsion Solvent Evaporation Method Using Block-Random Copolymer Surfactant Synthesized by RAFT Polymerization.

    PubMed

    Ezaki, Naofumi; Watanabe, Yoshifumi; Mori, Hideharu

    2015-10-27

    As surfactants for preparation of nonaqueous microcapsule dispersions by the emulsion solvent evaporation method, three copolymers composed of stearyl methacrylate (SMA) and glycidyl methacrylate (GMA) with different monomer sequences (i.e., random, block, and block-random) were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Despite having the same comonomer composition, the copolymers exhibited different functionality as surfactants for creating emulsions with respective dispersed and continuous phases consisting of methanol and isoparaffin solvent. The optimal monomer sequence for the surfactant was determined based on the droplet sizes and the stabilities of the emulsions created using these copolymers. The block-random copolymer led to an emulsion with better stability than obtained using the random copolymer and a smaller droplet size than achieved with the block copolymer. Modification of the epoxy group of the GMA unit by diethanolamine (DEA) further decreased the droplet size, leading to higher stability of the emulsion. The DEA-modified block-random copolymer gave rise to nonaqueous microcapsule dispersions after evaporation of methanol from the emulsions containing colored dyes in their dispersed phases. These dispersions exhibited high stability, and the particle sizes were small enough for application to the inkjet printing process. PMID:26421355

  17. Dynamic behaviors of oppositely charged emulsion droplets

    NASA Astrophysics Data System (ADS)

    Liu, Zhou; Wyss, Hans M.; Fernandez-Nieves, Alberto; Shum, Ho Cheung

    2014-11-01

    In this work, we investigate the dynamic behaviors of two oppositely charged emulsion droplets. Using an electrocapillary number and separation distance between droplets, we have characterized three types of droplet behaviors in electric field. Besides the common seen coalescence, two qualitatively different dynamic behaviors are identified: fuse-and-split and periodic non-coalescence. In fuse-and-split regime, the droplets fuse into a jet, which subsequently breaks up into two droplets. In periodic non-coalescence regime, the droplets contact and bounce away periodically without coalescence. Further analysis indicates that the applied voltage always decreases dramatically upon droplets' contact due to spikes of discharging current. Thus, the electric field strength drops and surface tension quickly dominates over electric stress upon droplet's contact. By analyzing capillary instability, all the observed dynamic states can be attributed to the different initial shapes of dumbbell-like jet formed upon droplets' contact. By controlling the initial separation distance between droplets, the shapes of the jet and thus the resultant dynamics can be precisely manipulated.

  18. Microwave selective heating for size effect of water droplet in W/O emulsion with sorbitan fatty acid monostearate surfactant

    NASA Astrophysics Data System (ADS)

    Sumi, Takuya; Horikoshi, Satoshi

    2015-09-01

    A stable water/oil (W/O) emulsion was prepared by adjustment with sorbitan fatty acid monoester surfactants. The prepared W/O emulsion was stable for 60 min in the atmosphere; however, the formation of non-uniform water droplets in the height of the emulsion in the quartz tube reactor were observed by the backscattering measurements with an infrared laser at 850 nm. The increase of temperature under microwave irradiation was influenced sensitively by the position of those water droplets. Those results were caused from the size and concentration of water droplets in the W/O emulsion. On the other hand, selective heating of the water droplets caused heating of the entire W/O emulsion, although the temperature difference between the water droplets and the oil phase was 20 °C.

  19. The effects of surfactant type, pH, and chelators on the oxidation of salmon oil-in-water emulsions.

    PubMed

    Mancuso, J R; McClements, D J; Decker, E A

    1999-10-01

    Lipid oxidation in emulsions is influenced by the ability of transition metals to associate with emulsion droplets. The oxidative stability of 5% salmon oil-in-water emulsion was influenced by surfactant type, with oxidation rates being greatest in emulsions stabilized by anionic sodium dodecyl sulfate (SDS) followed by nonionic Tween 20 and cationic dodecyltrimethylammonium bromide (DTAB). EDTA inhibited lipid oxidation in all the emulsions, and apo-transferrin inhibited oxidation in the Tween 20-stabilized emulsions at pH 7.0, suggesting that continuous-phase iron was an active prooxidant. Iron associated with Tween-20 stabilized hexadecane emulsion droplets could be partitioned into the continuous phase by lowering the pH to emulsions, and factors that increase iron-emulsion droplet interactions will increase oxidation rates. PMID:10552775

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

    SciTech Connect

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

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

  1. The efficient separation of surfactant-stabilized water-in-oil emulsions with a superhydrophobic filter paper

    NASA Astrophysics Data System (ADS)

    Ge, Bo; Zhu, Xiaotao; Li, Yong; Men, Xuehu; Li, Peilong; Zhang, Zhaozhu

    2015-11-01

    The filtration membranes have been acknowledged as efficient way for separation of emulsion. Nevertheless, most of the methods have limitations of high cost and complex fabrication process. Here, we present a simple method for preparing superhydrophobic/superoleophilic filter paper by solution immersion process. The superhydrophobic filter paper exhibited high selectivity for oil-water mixture. Importantly, the filter paper can be applied to separate surfactant-stabilized water-in-oil emulsion. Separation process is achieved by one step under gravity. Moreover, the superhydrophobic filter paper maintains stable superhydrophobicity and emulsion separation property after using for five cycles. We expected that this low-cost process can be used for water-in-oil emulsion separation.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  3. 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

  4. 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.

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

    PubMed

    Chidambaram, N; Burgess, D J

    2000-01-01

    A study was carried out to determine the effect of excess surfactant on transport kinetics in emulsions, using surface-active (phenobarbital, barbital) and non-surface-active (phenylazoaniline, benzocaine) model drugs (pH 7.0). Mineral oil was chosen as the oil phase, and the ionic surfactant cetyltrimethylammonium bromide (CTAB) was chosen as the emulsifier. The effect of nonionic surfactant Brij 97 on transport kinetics of these model drugs were determined by authors elsewhere. Model drug transport in the triphasic systems was investigated using side-by-side diffusion cells mounted with hydrophilic dialysis membranes (molecular weight cutoffs 1 kD and 50 kD) and a novel bulk equilibrium reverse dialysis bag technique. Emulsion stability was determined by droplet size analysis as a function of time, temperature, and the presence of model drugs using photon correlation spectroscopy. Mineral oil/water partition coefficients and aqueous solubilities were determined in the presence of surfactant. The droplet size of the CTAB-stabilized emulsion system is bigger than that of the Brij 97-stabilized system because of the relatively less dense interfacial packing of the cationic surfactant. CTAB forms a complex with the model drugs because of ionic interaction between CTAB and the aromatic and azo groups of the model drugs. This complexation is expected to increase emulsion stability and affect model drug transport kinetics. The transport rates of model drugs in emulsions increased with increases in CTAB micellar concentrations up to 0.5% w/v and then decreased at higher surfactant concentrations. Total transport rates of phenobarbital and barbital were faster than those of phenylazoaniline and benzocaine. Excess surfactant affected the transport rates of the model drugs in the emulsions depending on drug surface activity and lipophilicity. The transport profiles of the model drugs appeared to be governed by model drug oil/water partition coefficient values and by micellar shape changes at higher surfactant concentrations. PMID:11741244

  6. Flows of Wet Foamsand Concentrated Emulsions

    NASA Technical Reports Server (NTRS)

    Nemer, Martin B.

    2005-01-01

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

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

    PubMed

    Chidambaram, N; Burgess, D J

    2000-01-01

    The effect of surfactant concentration on transport kinetics in emulsions using surface-active (phenobarbital, barbital) and non- surface-active (phenylazoaniline, benzocaine) model drugs is determined. Mineral oil was chosen as the oil phase and the nonionic surfactant polyoxyethylene-10-oleyl-ether (Brij 97) was chosen as the emulsifier. Model drug transport in the triphasic systems was investigated using side-by-side diffusion cells mounted with hydrophilic dialysis membranes (molecular weight cutoffs 1 kd and 50 kd) and a novel bulk equilibrium reverse dialysis bag technique. Emulsion stability was determined by droplet size analysis as a function of time, temperature, and the presence of model drugs, using photon correlation spectroscopy. Mineral oil/water (O/W) partition coefficients and aqueous solubilities were determined in the presence of surfactant. The transport rates of model drugs in emulsions increased with an increase in Brij 97 micellar concentrations up to 1.0% wt/vol and then decreased at higher surfactant concentrations. The transport profiles of the model drugs appeared to be governed by model drug O/W partition coefficient values and by micellar shape changes at higher surfactant concentrations. Total transport rates of phenobarbital and barbital were faster than those of phenylazoaniline and benzocaine. Excess surfactant affected the transport rates of the model drugs in the emulsions depending on drug surface activity and lipophilicity. PMID:11741246

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

    PubMed Central

    Urbina-Villalba, German

    2009-01-01

    The first algorithm for Emulsion Stability Simulations (ESS) was presented at the V Conferencia Iberoamericana sobre Equilibrio de Fases y Diseño de Procesos [Luis, J.; García-Sucre, M.; Urbina-Villalba, G. Brownian Dynamics Simulation of Emulsion Stability In: Equifase 99. Libro de Actas, 1st Ed., Tojo J., Arce, A., Eds.; Solucion’s: Vigo, Spain, 1999; Volume 2, pp. 364–369]. The former version of the program consisted on a minor modification of the Brownian Dynamics algorithm to account for the coalescence of drops. The present version of the program contains elaborate routines for time-dependent surfactant adsorption, average diffusion constants, and Ostwald ripening. PMID:19399220

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

    PubMed

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

    2007-02-27

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

  10. Flexible Hierarchical TiO2 /Fe2 O3 Composite Membrane with High Separation Efficiency for Surfactant-Stabilized Oil-Water Emulsions.

    PubMed

    Tan, Benny Yong Liang; Juay, Jermyn; Liu, Zhaoyang; Sun, Darren

    2016-02-01

    Globally, efficient oil-water separation for surfactant-stabilized oil-water emulsions has been in urgent demand. The current options available for separation are neither sustainable nor resistant to fouling. Herein, we introduce a hierarchically nanostructured TiO2 /Fe2 O3 composite membrane, which is capable of separating surfactant-stabilized oil-water emulsions with high separation efficiency. The high oil rejection rate is contributed by the acquisition of an interconnected delicate network and underwater superoleophobic interface. Meanwhile, its self-cleaning function promote the facile recovery of the contaminated membrane. Furthermore, the mechanical flexible characteristic of the TiO2 /Fe2 O3 composite membrane widens its applicability in industrial employment. Thanks to these properties, this novel membrane can be considered as a practical option for treating surfactant-stabilized oil-water emulsions. PMID:26641598

  11. Surfactant effects on bio-based emulsions used as lubrication fluids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The successful formulation of a lubricating emulsion requires carefully balancing the mixture of base oil, water and a plethora of additives. The factors that affect the performance of lubrication emulsions range from the macroscopic stability to the microscopic surface properties of the base oil. ...

  12. Interaction behavior in ultrafiltration of nonionic surfactant micelles by adsorption.

    PubMed

    Xiarchos, Ioannis; Doulia, Danae

    2006-07-01

    Adsorption of nonionic surfactant micelles onto ultrafiltration (UF), membranes was studied. Two homologous series of nonionic surfactants, namely, Tritons (alkylphenol ethoxylates) and Neodols (alcohol ethoxylates), were used to characterize surface properties of two polymeric ultrafiltration membranes with 20,000 nominal cutoff. Particularly, a cellulose acetate and a polysulfone membrane were investigated. Static adsorption experiments were carried out using surfactant solutions at concentrations above their critical micelle concentration. The characterization of surface properties of UF membranes was based on the adsorption behavior of surfactant species. The adsorption extent on UF membranes was affected by the hydrophobicity-to-hydrophilicity ratio mainly determining the interactions developed at the membrane-surfactant species interface. Adsorption experimental data seem generally to fit the Langmuir isotherm model. Atomic force microscopy was used to examine the alteration of the top membrane surface morphology. PMID:16545839

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  14. Fischer-Tropsch diesel emulsions stabilised by microfibrillated cellulose and nonionic surfactants.

    PubMed

    Lif, Anna; Stenstad, Per; Syverud, Kristin; Nydén, Magnus; Holmberg, Krister

    2010-12-15

    Water-in-diesel emulsion fuels have been prepared with a combination of sorbitan monolaurate and glycerol monooleate as emulsifier and with microfibrillated cellulose (MFC) of different hydrophilic/hydrophobic character as stabilizer. The MFC was treated with either octadecylamine or poly(styrene-co-maleic anhydride), resulting in very hydrophobic fibrils. The most stable emulsion was achieved with a combination of hydrophilic (untreated) and hydrophobic MFC and only minute amounts of the stabilizer gave a pronounced effect. Even with the optimized formulation the lifetime of the emulsion was shorter than previously reported when a conventional polymeric stabilizer was used, however. The water drop sizes in the emulsions were determined by three methods: optical images, light scattering, and NMR diffusometry. All three methods gave water drops sizes of ca 2 μm. The NMR diffusometry indicated that besides the micrometer-sized emulsion drops a significant fraction of the water is present in small droplets of micelle size. The chemical exchange of water between these two populations of pools is believed to be the reason for the relatively low stability of the system. PMID:20864117

  15. Preparation of Inert Polystyrene Latex Particles as MicroRNA Delivery Vectors by Surfactant-Free RAFT Emulsion Polymerization.

    PubMed

    Poon, Cheuk Ka; Tang, Owen; Chen, Xin-Ming; Pham, Binh T T; Gody, Guillaume; Pollock, Carol A; Hawkett, Brian S; Perrier, Sébastien

    2016-03-14

    We present the preparation of 11 nm polyacrylamide-stabilized polystyrene latex particles for conjugation to a microRNA model by surfactant-free RAFT emulsion polymerization. Our synthetic strategy involved the preparation of amphiphilic polyacrylamide-block-polystyrene copolymers, which were able to self-assemble into polymeric micelles and "grow" into polystyrene latex particles. The surface of these sterically stabilized particles was postmodified with a disulfide-bearing linker for the attachment of the microRNA model, which can be released from the latex particles under reducing conditions. These nanoparticles offer the advantage of ease of preparation via a scaleable process, and the versatility of their synthesis makes them adaptable to a range of applications. PMID:26807678

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

    PubMed

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

    2012-03-01

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

  17. Phase behavior and formation of o/w nano-emulsion in vegetable oil/ mixture of polyglycerol polyricinoleate and polyglycerin fatty acid ester/water systems.

    PubMed

    Wakisaka, Satoshi; Nakanishi, Masami; Gohtani, Shoichi

    2014-01-01

    It is reported that mixing polyglycerol polyricinoleate (PGPR) and polyglycerol laurilester has a great emulsifying capacity, and consequently fine oil-in-water (o/w) emulsions can be formed. However, the role of PGPR is not clear. The objective of this research is to investigate the phase behavior of vegetable oil/mixture of PGPR and polyglycerol fatty acid ester/water systems, and to clarify the role of PGPR in making a fine emulsion. Phase diagrams were constructed to elucidate the optimal process for preparing fine emulsions. In all the systems examined in this study, the phases, including the liquid crystal phase (L(c)) and sponge phase (L(3)), spread widely in the phase diagrams. We examined droplet size of the emulsions prepared from each phase and found that o/w nano-emulsions with droplet sizes as small as 50 nm were formed by emulsifying either from a single L(3) phase or a two-phase region, L(c) + L(3). These results indicate that a sponge phase L(3) or liquid crystal phase L(c) or both is necessary to form an o/w nano-emulsion whose average droplet diameter is less than 50 nm for PGPR and polyglycerin fatty acid ester mixtures used as surfactant. PMID:24521844

  18. Coalescence behavior of oil droplets coated in irreversibly-adsorbed surfactant layers.

    PubMed

    Reichert, Matthew D; Walker, Lynn M

    2015-07-01

    Coalescence between oil caps with irreversibly adsorbed layers of nonionic surfactant is characterized in deionized water and electrolyte solution. The coalescence is characterized using a modified capillary tensiometer allowing for accurate measurement of the coalescence time. Results suggest two types of coalescence behavior, fast coalescence at low surface coverages that are independent of ionic strength and slow coalescence at high coverage. These slow coalescence events (orders of magnitude slower) are argued to be due to electric double layer forces or more complicated stabilization mechanisms arising from interfacial deformation and surface forces. A simple film drainage model is used in combination with measured values for interfacial properties to quantify the interaction potential between the two interfaces. Since this approach allows the two caps to have the same history, interfacial coverage and curvature, the results offer a tool to better understand a mechanism that is important to emulsion stability. PMID:25766654

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

    PubMed

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

    2014-07-21

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

  20. Injectable, interconnected, high-porosity macroporous biocompatible gelatin scaffolds made by surfactant-free emulsion templating.

    PubMed

    Oh, Bernice H L; Bismarck, Alexander; Chan-Park, Mary B

    2015-02-01

    High-porosity interconnected, thermoresponsive macroporous hydrogels are prepared from oil-in-water high internal phase emulsions (HIPEs) stabilized by gelatin-graft-poly(N-isopropylacrylamide). PolyHIPEs are obtained by gelling HIPEs utilizing the thermoresponsiveness of the copolymer components. PolyHIPEs properties can be controlled by varying the aqueous phase composition, internal phase volume ratio, and gelation temperature. PolyHIPEs respond to temperature changes experienced during cell seeding, allowing fibroblasts to spread, proliferate, and penetrate into the scaffold. Encapsulated cells survive ejection of cell-laden hydrogels through a hypodermic needle. This system provides a new strategy for the fabrication of safe injectable biocompatible tissue engineering scaffolds. PMID:25504548

  1. Surfactant Behavior of Amphiphilic Polymer-Tethered Nanoparticles.

    PubMed

    Zhang, Yue; Zhao, Hanying

    2016-04-19

    In recent years, an emerging research area has been the surfactant behavior of polymer-tethered nanoparticles. In this feature article, we have provided a general introduction to the synthesis, self-assembly, and interfacial activity of polymer-tethered inorganic nanoparticles, polymer-tethered organic nanoparticles, and polymer-tethered natural nanoparticles. In addition, applications of the polymer-tethered nanoparticles in colloidal and materials science are briefly reviewed. All research demonstrates that amphiphilic polymer-tethered nanoparticles exhibit surfactant behavior and can be used as elemental building blocks for the fabrication of advanced structures by the self-assembly approach. The polymer-tethered nanoparticles provide new opportunities to engineer materials and biomaterials possessing specific functionality and physical properties. PMID:27018567

  2. Low-temperature polymerization of methyl methacrylate emulsion gels through surfactant catalysis.

    PubMed

    Zhang, Tan; Xu, Gu; Regev, Oren; Blum, Frank D

    2016-01-01

    Poly(methyl methacrylate) (PMMA)/silica/cetyltrimethylammonium bromide (CTAB) composites were prepared through surfactant catalyzed free radical polymerizations at 40 °C. Fumed silica particles controlled the morphology of the polymeric composites producing porous structures. The internal structures of the porous composite were determined using temperature-modulated differential scanning calorimetry (TMDSC). The fumed silica particles were encapsulated by an incompletely covered CTAB monolayer, with a crystallization temperature, T(C,CTAB)=76 °C, and a mixed PMMA/CTAB shell, with T(C,CTAB)=63 °C. The fumed silica surfaces acted as inhibitors for PMMA free radical polymerizations. Much of the PMMA formed in the composites was adsorbed on the silica, as evidenced by its elevated glass transition temperature compared to bulk. The enhanced decomposition of the initiator was catalyzed by CTAB and resulted in free radical polymerization of PMMA at 40 °C, which is considerably lower than the temperatures normally used for PMMA synthesis by free radical means with thermal initiation. These lowered polymerization temperatures allow energy efficient production of composites, which can incorporate temperature sensitive materials. PMID:26397919

  3. 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

  4. 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

  5. Use of cetyltrimethylammonium bromide as surfactant for the determination of copper and chromium in gasoline emulsions by electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    dos Santos, Denilson S. S.; Teixeira, Alete P.; Barbosa, José T. P.; Ferreira, Sérgio L. C.; Korn, Maria das Graças A.; Teixeira, Leonardo S. G.

    2007-09-01

    In this work, the use of cetyltrimethylammonium bromide as surfactant for the preparation of oil-in-water emulsions for the determination of Cu and Cr in gasoline by electrothermal atomic absorption spectrometry (ET AAS) was evaluated. The surfactant amount was tested in the range of 25 to 300 mg, added to 2 ml of gasoline, and completed to 10 mL with 0.1% (v/v) nitric acid solution. 150 mg of surfactant was found optimum, and a sonication time of 10 min sufficient to form an oil-in-water emulsion that was stable for several hours. The ET AAS temperature program was established based on pyrolysis and atomization curves. The pyrolysis temperatures were set at 700 and 1300 °C for Cu and Cr, respectively and the selected atomization temperatures were 2400 and 2500 °C. The time and temperature of the drying stage and the atomization time were experimentally tested to provide optimum conditions. The limits of detection were found to be 5 μg L - 1 and 1.5 μg L - 1 for Cu and Cr, respectively in the original gasoline samples. The relative standard deviation (RSD) ranged from 4 to 9% in oil-in-water emulsions spiked with 5 μg L - 1 and 15 μg L - 1 of each metal, respectively. Recoveries varied from 90 to 98%. The accuracy of the proposed method was tested by an alternate procedure using complete evaporation of the gasoline sample. The method was adequate for the determination of Cu and Cr in gasoline samples collected from different gas stations in Salvador, BA, Brazil.

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

    SciTech Connect

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

    1992-03-01

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

  7. Anthocyanin antioxidant activity and partition behavior in whey protein emulsion.

    PubMed

    Viljanen, Kaarina; Kylli, Petri; Hubbermann, Eva-Maria; Schwarz, Karin; Heinonen, Marina

    2005-03-23

    The antioxidant activities of anthocyanins and anthocyanin fractions isolated from blackcurrants, raspberries, and lingonberries were investigated in whey protein-stabilized emulsion. The extent of protein oxidation was measured by determining the loss of tryptophan fluorescence and formation of protein carbonyl compounds and that of lipid oxidation by conjugated diene hydroperoxides and hexanal analyses. The antioxidant activity of berry anthocyanins increased with an increase in concentration. Blackcurrant anthocyanins were the most potent antioxidants toward both protein and lipid oxidation at all concentrations due to the beneficial combination of delphinidin and cyanidin glycosides. Most berry anthocyanins (69.4-72.8%) partitioned into the aqueous phase of the emulsion, thus being located favorably for antioxidant action toward protein oxidation. The presence of the lipid decreased the share of anthocyanin in the aqueous phase. Thus, the structure of food affects the antioxidant activity by influencing the partitioning of the antioxidant. PMID:15769130

  8. Pickering emulsions based on cyclodextrins: A smart solution for antifungal azole derivatives topical delivery.

    PubMed

    Leclercq, Loïc; Nardello-Rataj, Véronique

    2016-01-20

    Surfactants are usually used for the preparation of emulsions. Potential drawbacks on the human body or on the environment can be observed for some of them(e.g. skin irritation, hemolysis, protein denaturation, etc.). However, it is possible to use biocompatible emulsifiers such as native cyclodextrins (CDs). The mixture of oil (paraffin oil or isopropyl myristate), water and native CDs results in the formation of Pickering emulsions. The emulsion properties were investigated by ternary phase diagrams elaboration, multiple light scattering, optical and transmission microscopies. The results prove that these Pickering emulsions were very stable against coalescence due to the dense film format the oil/water interface. The rheological behavior has shown that these emulsions remain compatible for topical applications. This kind of emulsions (biocompatibility, stability and surfactant free) has been used to obtain sustainable formulations for antifungal econazole derivatives delivery. Our results prove that these new formulations are at least as active as commercially available formulations. PMID:26616822

  9. Tuneable Rheological Properties of Fluorinated Pickering Emulsions

    NASA Astrophysics Data System (ADS)

    Chacon Orellana, Laura Andreina; Riechers, Birte; Caen, Ouriel; Baret, Jean-Christophe

    Pickering emulsions are an appealing approach to stabilize liquid-liquid dispersions without surfactants. Recently, amphiphilic silica nanoparticles have been proposed as an alternative to surfactants for droplet microfluidics applications, where aqueous drops are stabilized in fluorinated oils. This system, proved to be effective in preventing the leakage of resorufin, a model dye that was known to leak in surfactant-stabilized drops. The overall capabilities of droplet-based microfluidics technology is highly dependent on the dynamic properties of droplets, interfaces and emulsions. Therefore, fluorinated pickering emulsions dynamic properties need to be characterized, understood and controlled to be used as a substitute of already broadly studied emulsions for droplet microfluidics applications. In this study, fluorinated pickering emulsions have been found to behave as a Herschel Bulkley fluid, representing a challenge for common microfluidic operations as re-injection and sorting of droplets. We found that this behavior is controlled by the interaction between the interfacial properties of the particle-laden interface and the bulk properties of the two phases

  10. 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.

  11. 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 β-sheet structure formed by the peptide spacer. PMID:25588349

  12. 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

  13. Multiple emulsions: an overview.

    PubMed

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

    2006-10-01

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

  14. The effect of surfactants on the dissolution behavior of amorphous formulations.

    PubMed

    Mah, Pei T; Peltonen, Leena; Novakovic, Dunja; Rades, Thomas; Strachan, Clare J; Laaksonen, Timo

    2016-06-01

    The optimal design of oral amorphous formulations benefits from the use of excipients to maintain drug supersaturation and thus ensures adequate absorption during intestinal transit. The use of surfactants for the maintenance of supersaturation in amorphous formulations has not been investigated in detail. The main aim of this study was to investigate the effect of surfactant on the dissolution behavior of neat amorphous drug and binary polymer based solid dispersion. Indomethacin was used as the model drug and the surfactants studied were polysorbate 80 and poloxamer 407. The presence of surfactants (alone or in combination with polymers) in the buffer was detrimental to the dissolution of neat amorphous indomethacin, suggesting that the surfactants promoted the crystallization of neat amorphous indomethacin. In contrast, the presence of surfactants (0.01% w/v) in the buffer resulted in a significant improvement on the dissolution behavior of binary polymer based solid dispersion. Incorporating the surfactant to the formulation to form ternary solid dispersion adversely affected the dissolution behavior. In conclusion, the use of surfactants (as wetting or solubilization agents) in dissolution studies of neat amorphous drugs requires prudent consideration. The design of amorphous formulations with optimal dissolution performance requires the appropriate selection of a combination of excipients and consideration of the method of introducing the excipients. PMID:26955750

  15. 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...

  16. Effect of glycation on the flocculation behavior of protein-stabilized oil-in-water emulsions.

    PubMed

    Delahaije, Roy J B M; Gruppen, Harry; van Nieuwenhuijzen, Neleke H; Giuseppin, Marco L F; Wierenga, Peter A

    2013-12-10

    Glycation of proteins by the Maillard reaction is often considered as a method to prevent flocculation of protein-stabilized oil-in-water emulsions. The effect has been suggested, but not proven, to be the result of steric stabilization, and to depend on the molecular mass of the carbohydrate moiety. To test this, the stabilities of emulsions of patatin glycated to the same extent with different mono- and oligosaccharides (xylose, glucose, maltotriose, and maltopentaose) were compared under different conditions (pH and electrolyte concentration). The emulsions with non-modified patatin flocculate under conditions in which the zeta potential is decreased (around the iso-electric point and at high ionic strength). The attachment of monosaccharides (i.e., glucose) did not affect the flocculation behavior. Attachment of maltotriose and maltopentaose (Mw > 500 Da), on the other hand, provided stability against flocculation at the iso-electric point. Since the zeta potential and the interfacial properties of the emulsion droplets are not affected by the attachment of the carbohydrate moieties, this is attributed to steric stabilization. Experimentally, a critical thickness of the adsorbed layer required for steric stabilization against flocculation was found to be 2.29-3.90 nm. The theoretical determination based on the DLVO interactions with an additional steric interaction coincides with the experimental data. Hence, it can be concluded that the differences in stability against pH-induced flocculation are caused by steric interactions. PMID:24188433

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

    NASA Astrophysics Data System (ADS)

    Flores, Gary E.; Loftus, James E.

    1992-06-01

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

  18. 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.

  19. Surfactants in aquatic and terrestrial environment: occurrence, behavior, and treatment processes.

    PubMed

    Jardak, K; Drogui, P; Daghrir, R

    2016-02-01

    Surfactants belong to a group of chemicals that are well known for their cleaning properties. Their excessive use as ingredients in care products (e.g., shampoos, body wash) and in household cleaning products (e.g., dishwashing detergents, laundry detergents, hard-surface cleaners) has led to the discharge of highly contaminated wastewaters in aquatic and terrestrial environment. Once reached in the different environmental compartments (rivers, lakes, soils, and sediments), surfactants can undergo aerobic or anaerobic degradation. The most studied surfactants so far are linear alkylbenzene sulfonate (LAS), quaternary ammonium compounds (QACs), alkylphenol ethoxylate (APEOs), and alcohol ethoxylate (AEOs). Concentrations of surfactants in wastewaters can range between few micrograms to hundreds of milligrams in some cases, while it reaches several grams in sludge used for soil amendments in agricultural areas. Above the legislation standards, surfactants can be toxic to aquatic and terrestrial organisms which make treatment processes necessary before their discharge into the environment. Given this fact, biological and chemical processes should be considered for better surfactants removal. In this review, we investigate several issues with regard to: (1) the toxicity of surfactants in the environment, (2) their behavior in different ecological systems, (3) and the different treatment processes used in wastewater treatment plants in order to reduce the effects of surfactants on living organisms. PMID:26590059

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

    SciTech Connect

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

    1982-04-01

    Killfish (Fundulus heteroclitus) and amphipods (Gammarus oceanicus) were exposed seperately to either a No. 2 fuel oil, AP dispersant, or emulsions of the two in a static system. Both species exhibited a concentration-dependent response to all three treatments. However, emulsification of oil with dispersant clearly increased its lethal effect on killfish survival, but did not cause a differential change in behavioral parameters such as schooling, chafing, substrate nipping, activity, or depth preference. Killfish exposed to conditions of thermal or osmotic stress were more sensitive to the lethal effects of emulsions. In contrast, emulsions caused quantitative changes in amphipod activity and precopulatory behavior, but did not increase mortality beyond that caused by exposure to oil alone. Changes in salinity had little effect on amphipod sensitivity to emulsions, but decreasing temperature did result in increased survival.

  1. Phase behavior and structures of mixtures of anionic and cationic surfactants

    SciTech Connect

    Kaler, E.W.; Herrington, K.L.; Murthy, A.K.

    1992-08-06

    This paper discusses how phase behavior and structural studies of a SDBS/CTAT mixture in H{sub 2}O reveals that vesicle formation results from an anion-cation surfactant pair that acts as a double-tailed zwitterionic surfactant. Over time, unilamellar vesicles revert to their equilibrium, multilamellar phase. These stable catanionic vesicles appear to be the equilibrium form of aggregation. 69 refs., 10 figs., 1 tab.

  2. Tensiometric and Phase Domain Behavior of Lung Surfactant on Mucus-like Viscoelastic Hydrogels.

    PubMed

    Schenck, Daniel M; Fiegel, Jennifer

    2016-03-01

    Lung surfactant has been observed at all surfaces of the airway lining fluids and is an important contributor to normal lung function. In the conducting airways, the surfactant film lies atop a viscoelastic mucus gel. In this work, we report on the characterization of the tensiometric and phase domain behavior of lung surfactant at the air-liquid interface of mucus-like viscoelastic gels. Poly(acrylic acid) hydrogels were formulated to serve as a model mucus with bulk rheological properties that matched those of tracheobronchial mucus secretions. Infasurf (Calfactant), a commercially available pulmonary surfactant derived from calf lung extract, was spread onto the hydrogel surface. The surface tension lowering ability and relaxation of Infasurf films on the hydrogels was quantified and compared to Infasurf behavior on an aqueous subphase. Infasurf phase domains during surface compression were characterized by fluorescence microscopy and phase shifting interferometry. We observed that increasing the bulk viscoelastic properties of the model mucus hydrogels reduced the ability of Infasurf films to lower surface tension and inhibited film relaxation. A shift in the formation of Infasurf condensed phase domains from smaller, more spherical domains to large, agglomerated, multilayer structures was observed with increasing viscoelastic properties of the subphase. These studies demonstrate that the surface behavior of lung surfactant on viscoelastic surfaces, such as those found in the conducting airways, differs significantly from aqueous, surfactant-laden systems. PMID:26894883

  3. Surfactant induced aggregation behavior of Merocyanine-540 adsorbed on polymer coated positively charged gold nanoparticles.

    PubMed

    Das, K; Uppal, A; Saini, R K

    2016-01-01

    Surfactant induced aggregation behavior of Merocyanine 540 adsorbed on polymer (PDD) coated gold nanoparticles (AuNP) is reported. The absorption band of the dye shifts to higher energy in the presence of free polymer and polymer coated AuNP implying aggregation. Addition of a negatively charged surfactant (SDS) induces multiple bands in the extinction spectrum of the dye adsorbed on nanoparticle surface. The highest (460nm) and lowest (564nm) energy bands of the dye become prominent at 10 and >50μM SDS concentrations respectively (dye: 10μM; AuNP: 100-200pM). Based on earlier results the high energy band is likely to originate from dye aggregates and the low energy band is likely to originate from dye monomers. This is attributed to the interplay between polymer-surfactant and polymer-dye interactions at the AuNP surface. The extinction spectra of dye adsorbed at AuNP surface remain unaffected in the presence of a positively charged (CTAB) or a neutral surfactant (Tx-100), at low surfactant concentrations. However at higher surfactant concentrations (>60μM) dye aggregation takes place which is attributed to dye-surfactant interactions. The fluorescence intensity of the dye quenched significantly but its lifetime increased in the presence of polymer coated AuNP. This is attributed to aggregation and reduction in the photoisomerization rate of the dye adsorbed on AuNP surface. PMID:26233787

  4. Surfactant induced aggregation behavior of Merocyanine-540 adsorbed on polymer coated positively charged gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Das, K.; Uppal, A.; Saini, R. K.

    2016-01-01

    Surfactant induced aggregation behavior of Merocyanine 540 adsorbed on polymer (PDD) coated gold nanoparticles (AuNP) is reported. The absorption band of the dye shifts to higher energy in the presence of free polymer and polymer coated AuNP implying aggregation. Addition of a negatively charged surfactant (SDS) induces multiple bands in the extinction spectrum of the dye adsorbed on nanoparticle surface. The highest (460 nm) and lowest (564 nm) energy bands of the dye become prominent at 10 and >50 μM SDS concentrations respectively (dye: 10 μM; AuNP: 100-200 pM). Based on earlier results the high energy band is likely to originate from dye aggregates and the low energy band is likely to originate from dye monomers. This is attributed to the interplay between polymer-surfactant and polymer-dye interactions at the AuNP surface. The extinction spectra of dye adsorbed at AuNP surface remain unaffected in the presence of a positively charged (CTAB) or a neutral surfactant (Tx-100), at low surfactant concentrations. However at higher surfactant concentrations (>60 μM) dye aggregation takes place which is attributed to dye-surfactant interactions. The fluorescence intensity of the dye quenched significantly but its lifetime increased in the presence of polymer coated AuNP. This is attributed to aggregation and reduction in the photoisomerization rate of the dye adsorbed on AuNP surface.

  5. Arsenic retention and transport behavior in the presence of typical anionic and nonionic surfactants.

    PubMed

    Liang, Chuan; Wang, Xianliang; Peng, Xianjia

    2016-01-01

    The massive production and wide use of surfactants have resulted in a large amount of surfactant residuals being discharged into the environment, which could have an impact on arsenic behavior. In the present study, the influence of the anionic surfactant sodium dodecyl benzene sulfonate (SDBS) and nonionic surfactant polyethylene glycol octylphenyl ether (Triton X-100) on arsenic behavior was investigated in batch and column tests. The presence of SDBS and Triton X-100 reduced arsenic retention onto ferrihydrite (FH), enhanced arsenic transport through FH coated sand (FH-sand) columns and promoted arsenic release from the FH surface. With coexisting surfactants in solution, the equilibrium adsorbed amount of arsenic on FH decreased by up to 29.7% and the adsorption rate decreased by up to 52.3%. Pre-coating with surfactants caused a decrease in the adsorbed amount and adsorption rate of arsenic by up to 15.1% and 58.3%, respectively. Because of the adsorption attenuation caused by surfactants, breakthrough of As(V) and As(III) with SDBS in columns packed with FH-sand was 23.8% and 14.3% faster than that in those without SDBS, respectively. In columns packed with SDBS-coated FH-sand, transport of arsenic was enhanced to a greater extent. Breakthrough of As(V) and As(III) was 52.4% and 43.8% faster and the cumulative retention amount was 44.5% and 57.3% less than that in pure FH-sand column systems, respectively. Mobilization of arsenic by surfactants increased with the increase of the initial adsorbed amount of arsenic. The cumulative release amount of As(V) and As(III) from the packed column reached 10.8% and 36.0%, respectively. PMID:26899663

  6. Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants

    PubMed Central

    Bouchal, Roza; Hamel, Abdellah; Hesemann, Peter; In, Martin; Prelot, Bénédicte; Zajac, Jerzy

    2016-01-01

    Surface activity and micelle formation of alkylguanidinium chlorides containing 10, 12, 14 and 16 carbon atoms in the hydrophobic tail were studied by combining conductivity and surface tension measurements with isothermal titration calorimetry. The purity of the resulting surfactants, their temperatures of Cr→LC and LC→I transitions, as well as their propensity of forming birefringent phases, were assessed based on the results of 1H and 13C NMR, differential scanning calorimetry (DSC), and polarizing microscopy studies. Whenever possible, the resulting values of Krafft temperature (TK), critical micelle concentration (CMC), minimum surface tension above the CMC, chloride counter-ion binding to the micelle, and the standard enthalpy of micelle formation per mole of surfactant (ΔmicH°) were compared to those characterizing alkyltrimethylammonium chlorides or bromides with the same tail lengths. The value of TK ranged between 292 and 314 K and increased strongly with the increase in the chain length of the hydrophobic tail. Micellization was described as both entropy and enthalpy-driven. Based on the direct calorimetry measurements, the general trends in the CMC with the temperature, hydrophobic tail length, and NaCl addition were found to be similar to those of other types of cationic surfactants. The particularly exothermic character of micellization was ascribed to the hydrogen-binding capacity of the guanidinium head-group. PMID:26861309

  7. Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants.

    PubMed

    Bouchal, Roza; Hamel, Abdellah; Hesemann, Peter; In, Martin; Prelot, Bénédicte; Zajac, Jerzy

    2016-01-01

    Surface activity and micelle formation of alkylguanidinium chlorides containing 10, 12, 14 and 16 carbon atoms in the hydrophobic tail were studied by combining conductivity and surface tension measurements with isothermal titration calorimetry. The purity of the resulting surfactants, their temperatures of Cr→LC and LC→I transitions, as well as their propensity of forming birefringent phases, were assessed based on the results of ¹H and (13)C NMR, differential scanning calorimetry (DSC), and polarizing microscopy studies. Whenever possible, the resulting values of Krafft temperature (TK), critical micelle concentration (CMC), minimum surface tension above the CMC, chloride counter-ion binding to the micelle, and the standard enthalpy of micelle formation per mole of surfactant (ΔmicH°) were compared to those characterizing alkyltrimethylammonium chlorides or bromides with the same tail lengths. The value of TK ranged between 292 and 314 K and increased strongly with the increase in the chain length of the hydrophobic tail. Micellization was described as both entropy and enthalpy-driven. Based on the direct calorimetry measurements, the general trends in the CMC with the temperature, hydrophobic tail length, and NaCl addition were found to be similar to those of other types of cationic surfactants. The particularly exothermic character of micellization was ascribed to the hydrogen-binding capacity of the guanidinium head-group. PMID:26861309

  8. Studies on interfacial behavior and wettability change phenomena by ionic and nonionic surfactants in presence of alkalis and salt for enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Mandal, Ajay

    2016-05-01

    Surfactant flooding is one of the most promising method of enhanced oil recovery (EOR) used after the conventional water flooding. The addition of alkali improves the performance of surfactant flooding due to synergistic effect between alkali and surfactant on reduction of interfacial tension (IFT), wettability alteration and emulsification. In the present study the interfacial tension, contact angle, emulsification and emulsion properties of cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and polysorbate 80 (Tween 80) surfactants against crude oil have been investigated in presence of sodium chloride (NaCl) and alkalis viz. sodium hydroxide (NaOH), sodium carbonate (Na2CO3), ammonium hydroxide (NH4OH), sodium metaborate (SMB) and diethanolamine (DEA). All three surfactants significantly reduce the IFT values, which are further reduced to ultra-low value (∼10-4 mN/m) by addition of alkalis and salt. It has been found experimentally that alkali-surfactant systems change the wettability of an intermediate-wet quartz rock to water-wet. Emulsification of crude oil by surfactant and alkali has also been investigated in terms of the phase volume and stability of emulsion. A comparative FTIR analysis of crude oil and different emulsions were performed to investigate the interactions between crude oil and displacing water in presence of surfactant and alkali.

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

    PubMed

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

    2014-04-01

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

  10. 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

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Kulaots, Indrek

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

  13. Phase behavior, formation, and rheology of cubic phase and related gel emulsion in Tween 80/water/oil systems.

    PubMed

    Alam, Mohammad Mydul; Ushiyama, Kousuke; Aramaki, Kenji

    2009-01-01

    We investigated the phase behavior, formation, and rheology of the cubic phase (I(1)) and related O/I(1) gel emulsion in water/Tween 80/oil systems using squalane, liquid paraffin (LP), and decane as oil components. In the phase behavior study, the phase sequences were similar for squalane and LP systems, while a lamellar liquid crystal (L(alpha)) was observed for decane system. In all the systems the addition of oil to W(m) or H(1) phase induced the I(1) phase, which can solubilize some amounts of oil followed by the appearance of I(1)+O phase. The formation of the O/I(1) gel emulsion has been studied at a fixed w/s (50/50) and we found that 30 wt% decane, 70 wt% squalane, and 60 wt% LP can form the gel emulsion. The water/Tween 80/squalane system has been taken as a model system to study viscoelastic properties of the I(1) phase and O/I(1) gel emulsion. The I(1) phase shows a typical hard gel cubic structure under the frequency and the values of the complex viscosity, /eta*/ and the elastic modulus, G ' increase with the addition of squalane, which could be due to the neighboring micellar interaction. On the other hand, the decreasing values of the viscoelastic parameters in the O/I(1) gel emulsion simply relate to the volume fraction of the I(1) phase in the system. PMID:19491531

  14. 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

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

    PubMed

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

    2010-09-29

    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 (C(8)E(4)), n-octylpentaoxyethylene (C(8)E(5)), n-decylhexaoxyethylene (C(10)E(6)), n-dodecylhexaoxyethylene (C(12)E(6)) and n-dodecyloctaoxylethylene (C(12)E(8)) - 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 C(8)E(4) and C(12)E(6). In contrast, C(8)E(5) and C(12)E(8) 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

  16. 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

  17. Viscoelastic behavior of surfactants worm-like micellar solution in the presence of alkanolamide.

    PubMed

    Varade, Dharmesh; Sharma, Suraj Chandra; Aramaki, Kenji

    2007-09-15

    A study of the phase and rheological behavior of anionic surfactant sodium dodecyl trioxyethylene sulfate (SDES) and nonionic polyoxyethylene sorbitan monooleate (Tween-80) with alkanoyl-N-methylethanolamide (C(12), NMEA-12; and C(16), NMEA-16) in aqueous system is presented. Upon addition of NMEA to the semi-dilute solution of SDES or Tween-80, induces micellar growth leading to the formation of a gel-like highly viscoelastic solution in the maximum viscosity region. These solutions obey the Maxwell model of a viscoelastic fluid. It was observed from rheological measurements that NMEA-16 is more effective than NMEA-12 to induce the micellar growth of surfactants. The relationship between the marked changes in viscosity with surfactant-cosurfactant mixing ratio based on the experimental observations is discussed. PMID:17540398

  18. 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

  19. Adsorption Behavior of Low-Concentration Imidazolium-Based Ionic Liquid Surfactant on Silica Nanoparticles.

    PubMed

    Liu, Yan; Qiao, Longjiao; Xiang, Yinping; Guo, Rong

    2016-03-22

    The adsorption behavior of imidazolium-based ionic liquid surfactant ([C12mim]Br) on silica nanoparticles (NPs) has been studied with turbidity, isothermal titration microcalorimetry, fluorescence spectroscopy, and dynamic light scattering (DLS) measurements. Both the electrostatic attraction and the hydrogen bonding interaction between silica NP and [C12mim]Br play crucial roles during [C12mim]Br monomers binding to silica NPs at low surfactant concentration, and the hydrophobic effect leads to formation of micelle-like aggregates on silica NP surfaces with the further increase of surfactant concentration. Furthermore, it is found that sodium halide salts favor the adsorption of [C12mim]Br on silica NP surfaces by decreasing the electrostatic repulsions. Anions with more hydrophobicity and the ability to form hydrogen bonding have more pronounced effect. Compared with DTAB, [C12mim]Br has much stronger binding ability with silica NPs at pH 7.0. More interestingly, [C12mim]Br can still form micelle-like aggregates on silica NP surfaces, but DTAB cannot at pH 2.0. The hydrogen bonding between the imidazolium ring and silica NPs is the principal contributor to these observations. Our results will contribute to the elucidation of silica NP/cationic surfactant interaction from molecular scale and the widely applications of silica NP/surfactant systems in practice. PMID:26923264

  20. Isotachophoresis with emulsions

    PubMed Central

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

    2013-01-01

    An experimental study on isotachophoresis (ITP) in which an emulsion is used as leading electrolyte (LE) is reported. The study aims at giving an overview about the transport and flow phenomena occurring in that context. Generally, it is observed that the oil droplets initially dispersed in the LE are collected at the ITP transition zone and advected along with it. The detailed behavior at the transition zone depends on whether or not surfactants (polyvinylpyrrolidon, PVP) are added to the electrolytes. In a system without surfactants, coalescence is observed between the droplets collected at the ITP transition zone. After having achieved a certain size, the droplets merge with the channel walls, leaving an oil film behind. In systems with PVP, coalescence is largely suppressed and no merging of droplets with the channel walls is observed. Instead, at the ITP transition zone, a droplet agglomerate of increasing size is formed. In the initial stages of the ITP experiments, two counter rotating vortices are formed inside the terminating electrolyte. The vortex formation is qualitatively explained based on a hydrodynamic instability triggered by fluctuations of the number density of oil droplets. PMID:24404037

  1. Direct Observation of Formation Behavior of Metal Emulsion in Sn/Salt System

    NASA Astrophysics Data System (ADS)

    Yoshida, Hironori; Liu, Jiang; Kim, Sun-Joong; Gao, Xu; Ueda, Shigeru; Maruoka, Nobuhiro; Ono, Shinpei; Kitamura, Shin-ya

    2016-05-01

    Using two systems with different interfacial tensions, the behavior of metal emulsions during bottom blowing was observed directly with a high-speed camera. The interfacial tension between molten salt (KCl-LiCl-NaCl) and molten Sn was measured by a pendant drop method, and it decreased to about 100 mN/m when the Te content in Sn increased from 0 to 0.5 pct. In both systems, two types of metal emulsion behaviors were observed. In Mode A, fine metal droplets were formed after the metal film ruptured at the interface. In Mode B, the formation of coarse droplets was observed after the disintegration of the column generated by the rising bubble, and the number of droplets increased with the gas flow rate compared to that in Mode A. The generating frequency of each mode revealed that Mode B became dominant with increasing gas flow rate. In the pure Sn/salt system, the numbers of droplets of Mode B showed a local maximum at high gas flow rates, but the numbers of droplets in Sn-0.5 pctTe/salt increased continuously even in the same flow range. Regarding the size distribution, the percentage of coarse metal droplets in the Sn-0.5 pctTe alloy/salt was larger than that in the pure Sn/salt. Furthermore, the effect of interfacial tension on the variation in surface area and volume of the droplets showed a similar tendency for the column height. Therefore, a decrement of the interfacial tension led to an increment of the column height when Mode B occurred and finally resulted in a higher interfacial area.

  2. O/W nano-emulsion formation using an isothermal low-energy emulsification method in a mixture of polyglycerol polyricinoleate and hexaglycerol monolaurate with glycerol system.

    PubMed

    Wakisaka, Satoshi; Nishimura, Takahisa; Gohtani, Shoichi

    2015-01-01

    We investigated how phase behavior changes by replacing water with glycerol in water/mixture of polyglycerol polyricinoleate (PGPR) and hexaglycerol monolaurate (HGML) /vegetable oil system, and studied the effect of glycerol on o/w nano-emulsion formation using an isothermal low-energy method. In the phase behavior study, the liquid crystalline phase (Lc) + the sponge phase (L3) expanded toward lower surfactant concentration when water was replaced with glycerol in a system containing surfactant HLP (a mixture of PGPR and HGML). O/W nano-emulsions were formed by emulsification of samples in a region of Lc + L3. In the glycerol/surfactant HLP/vegetable oil system, replacing water with glycerol was responsible for the expansion of a region containing Lc + L3 toward lower surfactant concentration, and as a result, in the glycerol/surfactant HLP/vegetable oil system, the region where o/w nano-emulsions or o/w emulsions could be prepared using an isothermal low-energy emulsification method was wide, and the droplet diameter of the prepared o/w emulsions was also smaller than that in the water/surfactant HLP/vegetable oil system. Therefore, glycerol was confirmed to facilitate the preparation of nano-emulsions from a system of surfactant HLP. Moreover, in this study, we could prepare o/w nano-emulsions with a simple one-step addition of water at room temperature without using a stirrer. Thus, the present technique is highly valuable for applications in several industries. PMID:25766932

  3. 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

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

    SciTech Connect

    Beckman, E.J. ); Smith, R.D. )

    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.

  5. Formation of thermally reversible optically transparent emulsion-based delivery systems using spontaneous emulsification.

    PubMed

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

    2015-12-28

    Transparent emulsion-based delivery systems suitable for encapsulating lipophilic bioactive agents can be fabricated using low-energy spontaneous emulsification methods. These emulsions are typically fabricated from non-ionic surfactants whose hydrophilic head groups are susceptible to dehydration upon heating. This phenomenon may promote emulsion instability due to enhanced droplet coalescence at elevated temperatures. Conversely, the same phenomenon can be used to fabricate optically transparent emulsions through the phase inversion temperature (PIT) method. The purpose of the current study was to examine the influence of oil phase composition and surfactant-to-oil ratio on the thermal behavior of surfactant-oil-water systems containing limonene, medium chain triglycerides (MCT), and Tween 60. Various types of thermal behavior (turbidity versus temperature profiles) were exhibited by these systems depending on their initial composition. For certain compositions, thermoreversible emulsions could be formed that were opaque at high temperatures but transparent at ambient temperatures. These systems may be particularly suitable for the encapsulation of bioactive agents in applications where optical clarity is important. PMID:26431057

  6. Surfactant-free alternative fuel: Phase behavior and diffusion properties.

    PubMed

    Kayali, Ibrahim; Jyothi, Chemboli K; Qamhieh, Khawla; Olsson, Ulf

    2016-02-01

    Phase behavior of the three components, 1-propanol, water and oil is studied at 10, 25, and 40°C. Biodiesel, limonene and diesel are used as oil phases. NMR self-diffusion measurements are performed to investigate the microstructure of the one-phase regions. Tie lines in the two-phase regions are determined both by proton NMR analysis and compared with theoretical calculations. NMR self-diffusion results for the different components in these systems do not show any sign of confinement or obstructions, demonstrating these mixtures to be structureless solutions. A good agreement between the experimental and calculated phase behavior is obtained. The determined tie lines in the two-phase regions show higher affinity of 1-propanol to water than to oil. PMID:26520824

  7. Synthesis and Monolayer Behaviors of Succinic Acid-Type Gemini Surfactants Containing Semifluoroalkyl Groups.

    PubMed

    Kawase, Tokuzo; Nagase, Youhei; Oida, Tatsuo

    2016-01-01

    In this work, novel succinic acid-type gemini surfactants containing semifluoroalkyl groups, dl- and meso-2,3-bis[Rf-(CH2)n]-succinic acids (Rf = C4F9, C6F13, C8F17; n = 2, 9), were successfully synthesized, and the effects of Rf, methylene chain length (n), and stereochemistry on their monolayer behaviors were studied. Critical micelle concentrations (CMC) of dl- and meso-2,3-bis[C4F9(CH2)9]-succinic acids were one order of magnitude smaller than that of the corresponding 1+1 type surfactant, C4F9(CH2)9COOH. From surface pressure-area (π-A) measurements, the lift-off areas of the geminis were found to decrease in the order C4F9 ≥ C6F13 > C8F17, regardless of methylene chain length and stereochemistry. The zero-pressure molecular areas of the geminis were twice those of the corresponding 1+1 type surfactants. Based on Gibbs compression modulus analysis, it was clarified that 2,3-bis[C8F17(CH2)n]-succinic gemini with short methylene chains (n = 2) would form more rigid monolayers than those having long methylene chains (n = 9). Unlike for 2,3-bis(alkyl)-succinic acids, the effects of stereochemistry on the monolayer behavior of semifluoroalkylated geminis were small. PMID:26743669

  8. Surfactant Behavior of Sodium Dodecylsulfate in Deep Eutectic Solvent Choline Chloride/Urea.

    PubMed

    Arnold, T; Jackson, A J; Sanchez-Fernandez, A; Magnone, D; Terry, A E; Edler, K J

    2015-12-01

    Deep eutectic solvents (DES) resemble ionic liquids but are formed from an ionic mixture instead of being a single ionic compound. Here we present some results that demonstrate that surfactant sodium dodecyl sulfate (SDS) remains surface-active and shows self-assembly phenomena in the most commonly studied DES, choline chloride/urea. X-ray reflectivity (XRR) and small angle neutron scattering (SANS) suggest that the behavior is significantly different from that in water. Our SANS data supports our determination of the critical micelle concentration using surface-tension measurements and suggests that the micelles formed in DES do not have the same shape and size as those seen in water. Reflectivity measurements have also demonstrated that the surfactants remain surface-active below this concentration. PMID:26540438

  9. Thermotropic behavior of asymmetric chain length catanionic surfactants: the influence of the polar head group.

    PubMed

    Silva, Bruno F B; Marques, Eduardo F

    2005-10-01

    Catanionic surfactants formed by the pairing of two ionic amphiphilic chains of opposite charge are now recognized as an important class of amphiphiles. Many aspects of their phase behavior have yet to be explored. In this work, two homologous series of catanionic surfactants were synthesized, based on the cationic headgroups trimethylammonium and pyridinium. Within each series, the headgroup and chain length of the cationic counterpart remains constant while for the anionic counterpart the headgroup is varied, while its alkyl chain length is also kept constant. Thus, one can directly monitor the influence of headgroup chemistry on the thermal behavior of these compounds. Differential scanning calorimetry (DSC) and polarizing light microscopy show that these compounds bear a rich and often complex thermotropic behavior, with the headgroup chemistry in some instances having a rather dramatic influence on phase behavior. Several liquid crystalline phases appear between the solid crystalline phase and the isotropic liquid phase. A qualitative correlation between the observed thermotropic behavior and the chemical nature of headgroup is presented. PMID:15936766

  10. 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.

  11. Aggregation behavior of tetracarboxylic surfactants derived from cholic and deoxycholic acids and ethylenediaminetetraacetic acid.

    PubMed

    Alvarez Alcalde, Mercedes; Jover, Aida; Meijide, Francisco; Galantini, Luciano; Viorel Pavel, Nicolae; Antelo, Alvaro; Vázquez Tato, José

    2009-08-18

    The reaction of 3beta-aminoderivatives of cholic and deoxycholic acids (steroid residues) with dimethyl ester of ethylenediaminetetraacetic acid (bridge) leads to the formation of dimers carrying four carboxylic organic functions, two of them located on the side chain of each steroid residue and the other two on the bridge. As tetrasodium salts, these new compounds behave as surfactants and have been characterized by surface tension, fluorescence intensity of pyrene (as a probe), and static and dynamic light scattering measurements. Thermodynamic parameters for micellization were obtained from the dependence of the critical micelle concentration (cmc) with temperature. For both surfactants, the fraction of bound counterions is close to 0.5. The aggregation behavior is similar to one of their bile salt residues [i.e., sodium cholate (NaC) and sodium deoxycholate (NaDC)] and can be summarized as follows: (i) molecular areas at the interface for the new surfactants are fairly close to twice the value for a single molecule in a monolayer of natural bile salts; (ii) the environment where pyrene is solubilized is very apolar, as in natural bile salt aggregates; (iii) Gibbs free energies (per steroid residue) for micellization are not far from published values for NaC and NaDC, and the differences can be understood on the basis of less hydrophobicity of the new surfactants due to the charges in the bridge; and (iv) as for NaC and NaDC, aggregates have rather low aggregation numbers (which depend on the amount of added inert salt, NaCl). A structure based on the disklike model accepted for small bile salt aggregates is proposed. PMID:19719219

  12. 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

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

    PubMed

    Xie, Dan Hua; Zhao, Jianxi

    2013-01-15

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

  14. Drops and emulsions with complex interfaces

    NASA Astrophysics Data System (ADS)

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

    2007-11-01

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

  15. Persurf, a New Method to Improve Surfactant Delivery: A Study in Surfactant Depleted Rats

    PubMed Central

    Ochs, Matthias; Proquitté, Hans; Mense, Lars; Rüdiger, Mario

    2012-01-01

    Purpose Exogenous surfactant is not very effective in adults with ARDS, since surfactant does not reach atelectatic alveoli. Perfluorocarbons (PFC) can recruit atelectatic areas but do not replace impaired endogenous surfactant. A surfactant-PFC-mixture could combine benefits of both therapies. The aim of the proof-of-principal-study was to produce a PFC-in-surfactant emulsion (Persurf) and to test in surfactant depleted Wistar rats whether Persurf achieves I.) a more homogenous pulmonary distribution and II.) a more homogenous recruitment of alveoli when compared with surfactant or PFC alone. Methods Three different PFC were mixed with surfactant and phospholipid concentration in the emulsion was measured. After surfactant depletion, animals either received 30 ml/kg of PF5080, 100 mg/kg of stained (green dye) Curosurf™ or 30 ml/kg of Persurf. Lungs were fixated after 1 hour of ventilation and alveolar aeration and surfactant distribution was estimated by a stereological approach. Results Persurf contained 3 mg/ml phospholipids and was stable for more than 48 hours. Persurf-administration improved oxygenation. Histological evaluation revealed a more homogenous surfactant distribution and alveolar inflation when compared with surfactant treated animals. Conclusions In surfactant depleted rats administration of PFC-in-surfactant emulsion leads to a more homogenous distribution and aeration of the lung than surfactant alone. PMID:23082229

  16. Multiwalled Carbon Nanotubes at the Interface of Pickering Emulsions.

    PubMed

    Briggs, Nicholas M; Weston, Javen S; Li, Brian; Venkataramani, Deepika; Aichele, Clint P; Harwell, Jeffrey H; Crossley, Steven P

    2015-12-01

    Carbon nanotubes exhibit very unique properties in biphasic systems. Their interparticle attraction leads to reduced droplet coalescence rates and corresponding improvements in emulsion stability. Here we use covalent and noncovalent techniques to modify the hydrophilicity of multiwalled carbon nanotubes (MWCNTs) and study their resulting behavior at an oil-water interface. By using both paraffin wax/water and dodecane/water systems, the thickness of the layer of MWNTs at the interface and resulting emulsion stability are shown to vary significantly with the approach used to modify the MWNTs. Increased hydrophilicity of the MWNTs shifts the emulsions from water-in-oil to oil-in-water. The stability of the emulsion is found to correlate with the thickness of nanotubes populating the oil-water interface and relative strength of the carbon nanotube network. The addition of a surfactant decreases the thickness of nanotubes at the interface and enhances the overall interfacial area stabilized at the expense of increased droplet coalescence rates. To the best of our knowledge, this is the first time the interfacial thickness of modified carbon nanotubes has been quantified and correlated to emulsion stability. PMID:26549532

  17. The effect of oil components on the physicochemical properties and drug delivery of emulsions: tocol emulsion versus lipid emulsion.

    PubMed

    Hung, Chi-Feng; Fang, Chia-Lang; Liao, Mei-Hui; Fang, Jia-You

    2007-04-20

    An emulsion system composed of vitamin E, coconut oil, soybean phosphatidylcholine, non-ionic surfactants, and polyethylene glycol (PEG) derivatives (referred to as the tocol emulsion) was characterized in terms of its physicochemical properties, drug release, in vivo efficacy, toxicity, and stability. Systems without vitamin E (referred to as the lipid emulsion) and without any oils (referred to as the aqueous micelle system) were prepared for comparison. A lipophilic antioxidant, resveratrol, was used as the model drug for emulsion loading. The incorporation of Brij 35 and PEG derivatives reduced the vesicle diameter to <100nm. The inclusion of resveratrol into the emulsions and aqueous micelles retarded the drug release. The in vitro release rate showed a decrease in the order of aqueous micelle system>tocol emulsion>lipid emulsion. Treatment of resveratrol dramatically reduced the intimal hyperplasia of the injured vascular wall in rats. There was no significant difference in this reduction when resveratrol was delivered by either emulsion or the aqueous micelle system. The percentages of erythrocyte hemolysis by the emulsions and aqueous micelle system were approximately 0 and approximately 10%, respectively. Vitamin E prevented the aggregation of emulsion vesicles. The mean vesicle size of the tocol emulsion remained unchanged during 30 days at 37 degrees C. The lipid emulsion and aqueous micelle system, respectively, showed 11- and 16-fold increases in vesicle size after 30 days of storage. PMID:17129692

  18. 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.

  19. Interfacial mechanisms in active emulsions.

    PubMed

    Herminghaus, Stephan; Maass, Corinna C; Krüger, Carsten; Thutupalli, Shashi; Goehring, Lucas; Bahr, Christian

    2014-09-28

    Active emulsions, i.e., emulsions whose droplets perform self-propelled motion, are of tremendous interest for mimicking collective phenomena in biological populations such as phytoplankton and bacterial colonies, but also for experimentally studying rheology, pattern formation, and phase transitions in systems far from thermal equilibrium. For fuelling such systems, molecular processes involving the surfactants which stabilize the emulsions are a straightforward concept. We outline and compare two different types of reactions, one which chemically modifies the surfactant molecules, the other which transfers them into a different colloidal state. While in the first case symmetry breaking follows a standard linear instability, the second case turns out to be more complex. Depending on the dissolution pathway, there is either an intrinsically nonlinear instability, or no symmetry breaking at all (and hence no locomotion). PMID:24924906

  20. Thermally cleavable surfactants

    DOEpatents

    McElhanon, James R.; Simmons, Blake A.; Zifer, Thomas; Jamison, Gregory M.; Loy, Douglas A.; Rahimian, Kamyar; Long, Timothy M.; Wheeler, David R.; Staiger, Chad L.

    2009-09-29

    Two new surfactant molecules are reported which contain thermally labile Diels-Alder adducts connecting the polar and non-polar sections of each molecule. The two surfactants possess identical non-polar dodecyl tail segments but exhibit different polar headgroups. The surfactants become soluble in water when anionic salts are formed through the deprotonation of the surfactant headgroups by the addition of potassium hydroxide. When either surfactant is exposed to temperature above about 60.degree. C., the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments or the aqueous solutions of the surfactants subsequently exhibit loss of all surface-active behavior.

  1. Thermally cleavable surfactants

    DOEpatents

    McElhanon, James R.; Simmons, Blake A.; Zifer, Thomas; Jamison, Gregory M.; Loy, Douglas A.; Rahimian, Kamyar; Long, Timothy M.; Wheeler, David R.; Staiger, Chad L.

    2009-11-24

    Two new surfactant molecules are reported which contain thermally labile Diels-Alder adducts connecting the polar and non-polar sections of each molecule. The two surfactants possess identical non-polar dodecyl tail segments but exhibit different polar headgroups. The surfactants become soluble in water when anionic salts are formed through the deprotonation of the surfactant headgroups by the addition of potassium hydroxide. When either surfactant is exposed to temperature above about 60.degree. C., the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments or the aqueous solutions of the surfactants subsequently exhibit loss of all surface-active behavior.

  2. Thermally cleavable surfactants

    DOEpatents

    McElhanon, James R.; Simmons, Blake A.; Zifer, Thomas; Jamison, Gregory M.; Loy, Douglas A.; Rahimian, Kamyar; Long, Timothy M.; Wheeler, David R.; Staiger, Chad L.

    2006-04-04

    Two new surfactant molecules are reported which contain thermally labile Diels-Alder adducts connecting the polar and non-polar sections of each molecule. The two surfactants possess identical non-polar dodecyl tail segments but exhibit different polar headgroups. The surfactants become soluble in water when anionic salts are formed through the deprotonation of the surfactant headgroups by the addition of potassium hydroxide. When either surfactant is exposed to temperature above about 60.degree. C., the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments and the aqueous solutions of the surfactants subsequently exhibit loss of all surface-active behavior.

  3. Photothermal Breaking of Emulsions Stabilized with Graphene.

    PubMed

    Quinn, Matthew D J; Vu, Khu; Madden, Stephen; Notley, Shannon M

    2016-04-27

    Pristine graphene particles prepared using an aqueous phase exfoliation technique have been used to promote the stabilization of emulsions through adsorption at the oil-water interface. Highly localized phase separation of these ultrastable emulsions could, however, be induced through photothermal heating of the graphene particles at the interface exposed to near-infrared light. The graphene wettability, which is a key determinant in preventing droplet coalescence was altered through the adsorption of nonionic block copolymer surfactants. Varying the aqueous solution conditions influenced the hydration of the hydrophilic component of the surfactant providing a further opportunity to alter the overall particle wettability and, hence, stability of the emulsion. In this way, highly stable-oil-in water emulsions were produced with decane; however, water-in-oil emulsions were formed with toluene as the oil phase. PMID:27054548

  4. 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

  5. Molecular-thermodynamic approach to predict micellization, phase behavior and phase separation of micellar solutions. I. Application to nonionic surfactants

    NASA Astrophysics Data System (ADS)

    Puvvada, Sudhakar; Blankschtein, Daniel

    1990-03-01

    We present a detailed description of a molecular-thermodynamic approach which consists of blending a molecular model of micellization with a thermodynamic theory of phase behavior and phase separation of isotropic (surfactant-water) micellar solutions. The molecular model incorporates the effects of solvent properties and surfactant molecular architecture on physical factors which control micelle formation and growth. These factors include (i) hydrophobic interactions between surfactant hydrocarbon chains and water, (ii) conformational effects associated with hydrocarbon-chain packing in the micellar core, (iii) curvature-dependent interfacial effects at the micellar core-water interface, and (iv) steric and electrostatic interactions between surfactant hydrophilic moieties. The free energy of micellization gmic is computed for various micellar shapes Sh and micellar-core minor radii lc. The ``optimum'' equilibrium values, l*c, Sh*, and g*mic, are obtained by minimizing gmic with respect to lc and Sh. The deduced ``optimum'' micellar shape Sh* determines whether the micelles exhibit two-dimensional, one-dimensional, or no growth. These results are then utilized in the thermodynamic theory to predict a broad spectrum of micellar solution equilibrium properties as a function of surfactant concentration and temperature. These properties include (1) the critical micellar concentration, (2) the micellar size distribution, (3) the critical surfactant concentration for the onset of phase separation, and (4) other thermodynamic properties such as the osmotic compressibility. The proposed molecular-thermodynamic approach provides an excellent description of a wide range of experimental findings in aqueous solutions of nonionic surfactants belonging to the polyoxyethylene glycol monoether and glucoside families.

  6. Alkyl-Based Surfactants at a Liquid Mercury Surface: Computer Simulation of Structure, Self-Assembly, and Phase Behavior.

    PubMed

    Iakovlev, Anton; Bedrov, Dmitry; Müller, Marcus

    2016-04-21

    Self-assembled organic films on liquid metals feature a very rich phase behavior, which qualitatively differs from the one on crystalline metals. In contrast to conventional crystalline supports, self-assembled alkylthiol monolayers on liquid metals possess a considerably higher degree of molecular order, thus enabling much more robust metal-molecule-semiconductor couplings for organic electronics applications. Yet, compared to crystalline substrates, the self-assembly of organic surfactants on liquid metals has been studied to a much lesser extent. In this Letter we report the first of its kind molecular simulation investigation of alkyl-based surfactants on a liquid mercury surface. The focus of our investigation is the surfactant conformations as a function of surface coverage and surfactant type. First, we consider normal alkanes because these systems set the basis for simulations of all other organic surfactants on liquid mercury. Subsequently, we proceed with the discussion of alkylthiols that are the most frequently used surfactants in the surface science of hybrid organometallic interfaces. Our results indicate a layering transition of normal alkanes as well as alkylthiols from an essentially bare substrate to a completely filled monolayer of laying molecules. As the surface coverage increases further, we observe a partial wetting of the laying monolayer by the bulk phase of alkanes. In the case of alkylthiols, we clearly see the coexistence of molecules in laying-down and standing-up conformations, in which the sulfur headgroups of the thiols are chemically bound to mercury. In the standing-up phase, the headgroups form an oblique lattice. For the first time we were able to explicitly characterize the molecular-scale structure and transitions between phases of alkyl-based surfactants and to demonstrate how the presence of a thiol headgroup qualitatively changes the phase equilibrium and structure in these systems. The observed phenomena are consistent with available direct and indirect experimental evidence. PMID:27045619

  7. Magnetically Targeted Nanocapsules for PAA-Cisplatin-Conjugated Cores in PVA/SPIO Shells via Surfactant-Free Emulsion for Reduced Nephrotoxicity and Enhanced Lung Cancer Therapy.

    TOXLINE Toxicology Bibliographic Information

    Chiang CS; Tseng YH; Liao BJ; Chen SY

    2015-05-01

    Cis-diamminedichloroplatinum (II) (cisplatin, CDDP) is one of the most potent chemotherapy agents, but its side effects toward normal tissues, particularly toxicity in the kidney and nonspecific biodistribution, limit its ability to have significant clinical activity against a variety of solid tumors. A magnetic CDDP-encapsulated nanocapsule (CDDP-PAA-NC) with CDDP-polyacrylic acid (PAA) core in amphiphilic polyvinyl alcohol/superparamagnetic iron oxide nanoparticles shell is synthesized through a double emulsion to provide both high loading efficiency and controlled drug release. The CDDP-PAA-NCs significantly increase the blood circulation time of CDDP in vivo, with nearly 100-fold higher concentration, and drastically reduce side effects, including nephrotoxicity and hepatotoxicity, compared with the delivery of free CDDP. Furthermore, with a magnetic targeting effect, the CDDP-PAA-NCs show ninefold higher level accumulation in tumor tissue than the free CDDP treatment when administered at the equivalent dose, and mice treated with the CDDP-PAA-NCs display approximately 3.5-fold lower tumor volume than those of the control group on day 24. This result demonstrates that the magnetic CDDP-PAA-NCs, which are synthesized using a facile emulsion process, can significantly reduce toxicity and exhibit anticancer activity in A549-tumor bearing mice with negligible side effects.

  8. Magnetically Targeted Nanocapsules for PAA-Cisplatin-Conjugated Cores in PVA/SPIO Shells via Surfactant-Free Emulsion for Reduced Nephrotoxicity and Enhanced Lung Cancer Therapy.

    PubMed

    Chiang, Chih-Sheng; Tseng, Yi-Hsuan; Liao, Bang-Jie; Chen, San Yuan

    2015-05-01

    Cis-diamminedichloroplatinum (II) (cisplatin, CDDP) is one of the most potent chemotherapy agents, but its side effects toward normal tissues, particularly toxicity in the kidney and nonspecific biodistribution, limit its ability to have significant clinical activity against a variety of solid tumors. A magnetic CDDP-encapsulated nanocapsule (CDDP-PAA-NC) with CDDP-polyacrylic acid (PAA) core in amphiphilic polyvinyl alcohol/superparamagnetic iron oxide nanoparticles shell is synthesized through a double emulsion to provide both high loading efficiency and controlled drug release. The CDDP-PAA-NCs significantly increase the blood circulation time of CDDP in vivo, with nearly 100-fold higher concentration, and drastically reduce side effects, including nephrotoxicity and hepatotoxicity, compared with the delivery of free CDDP. Furthermore, with a magnetic targeting effect, the CDDP-PAA-NCs show ninefold higher level accumulation in tumor tissue than the free CDDP treatment when administered at the equivalent dose, and mice treated with the CDDP-PAA-NCs display approximately 3.5-fold lower tumor volume than those of the control group on day 24. This result demonstrates that the magnetic CDDP-PAA-NCs, which are synthesized using a facile emulsion process, can significantly reduce toxicity and exhibit anticancer activity in A549-tumor bearing mice with negligible side effects. PMID:25656800

  9. Preparation of microemulsions with soybean oil-based surfactants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Emulsions are widely applied in food, cosmeceutical and medicinal formulations. Smaller and highly stable droplets of emulsions are important for their application. This research reports that by using soybean oil-based surfactants, the higher stabilized oil-in-water emulsions were obtained via an ul...

  10. 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

  11. 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.

  12. 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.

  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. 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.

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

    PubMed

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

    2012-06-01

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

  16. Surface phase stability and surfactant behavior of InAsSb alloy surfaces.

    NASA Astrophysics Data System (ADS)

    Anderson, Evan M.; Lundquist, Adam M.; Pearson, Chris; Millunchick, Joanna M.

    InAsSb has the narrowest bandgap of any of the conventional III-V semiconductors: low enough for long wavelength infrared applications. Such devices are sensitive to point defects, which can be detrimental to performance. To control these defects, all aspects of synthesis must be considered, especially the atomic bonding at the surface. We use an ab initio statistical mechanics approach that combines density functional theory with a cluster expansion formalism to determine the stable surface reconstructions of Sb (As) on InAs (InSb) substrates. The surface phase diagram of Sb on InAs is dominated by Sb-dimer termination α2(2x4) and β2(2x4) and c(4x4). Smaller regions of mixed Sb-As dimers appear for high Sb chemical potentials and intermediate As chemical potential. We propose that InAsSb films could be grown on (2x4), which maintain bulk-like stoichiometry, to eliminate the formation of typically observed n-type defects. Scanning tunneling microscopy and reflection high energy electron diffraction confirm the calculated phase diagram. Based on these calculations, we propose a new mechanism for the surfactant behavior of Sb in these materials. We gratefully acknowledge Chakrapani Varanasi and the support of the Department of Defense, Army Research Office via the Grant Number W911NF-12-1-0338.

  17. Analysis of emulsion stability in acrylic dispersions

    NASA Astrophysics Data System (ADS)

    Ahuja, Suresh

    2012-02-01

    Emulsions either micro or nano permit transport or solubilization of hydrophobic substances within a water-based phase. Different methods have been introduced at laboratory and industrial scales: mechanical stirring, high-pressure homogenization, or ultrasonics. In digital imaging, toners may be formed by aggregating a colorant with a latex polymer formed by batch or semi-continuous emulsion polymerization. Latex emulsions are prepared by making a monomer emulsion with monomer like Beta-carboxy ethyl acrylate (β-CEA) and stirring at high speed with an anionic surfactant like branched sodium dodecyl benzene sulfonates , aqueous solution until an emulsion is formed. Initiator for emulsion polymerization is 2-2'- azobis isobutyramide dehydrate with chain transfer agent are used to make the latex. If the latex emulsion is unstable, the resulting latexes produce a toner with larger particle size, broader particle size distribution with relatively higher latex sedimentation, and broader molecular weight distribution. Oswald ripening and coalescence cause droplet size to increase and can result in destabilization of emulsions. Shear thinning and elasticity of emulsions are applied to determine emulsion stability.

  18. Interactions between Surfactants in Solution and Electrospun Protein Fibers: Effects on Release Behavior and Fiber Properties.

    PubMed

    Stephansen, Karen; García-Díaz, María; Jessen, Flemming; Chronakis, Ioannis S; Nielsen, Hanne M

    2016-03-01

    Intermolecular interaction phenomena occurring between endogenous compounds, such as proteins and bile salts, and electrospun compounds are so far unreported, despite the exposure of fibers to such biorelevant compounds when applied for biomedical purposes, e.g., tissue engineering, wound healing, and drug delivery. In the present study, we present a systematic investigation of how surfactants and proteins, as physiologically relevant components, interact with insulin-loaded fish sarcoplasmic protein (FSP) electrospun fibers (FSP-Ins fibers) in solution and thereby affect fiber properties such as accessible surface hydrophilicity, physical stability, and release characteristics of an encapsulated drug. Interactions between insulin-loaded protein fibers and five anionic surfactants (sodium taurocholate, sodium taurodeoxycholate, sodium glycocholate, sodium glycodeoxycholate, and sodium dodecyl sulfate), a cationic surfactant (benzalkonium chloride), and a neutral surfactant (Triton X-100) were studied. The anionic surfactants increased the insulin release in a concentration-dependent manner, whereas the neutral surfactant had no significant effect on the release. Interestingly, only minute amounts of insulin were released from the fibers when benzalkonium chloride was present. The FSP-Ins fibers appeared dense after incubation with this cationic surfactant, whereas high fiber porosity was observed after incubation with anionic or neutral surfactants. Contact angle measurements and staining with the hydrophobic dye 8-anilino-1-naphthalenesulfonic acid indicated that the FSP-Ins fibers were hydrophobic, and showed that the fiber surface properties were affected differently by the surfactants. Bovine serum albumin also affected insulin release in vitro, indicating that also proteins may affect the fiber performance in an in vivo setting. PMID:26389817

  19. 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 (ΔGm°) 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 θt than IP as a cosurfactant (in the absence of NaCMC) at comparable ω. 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 ω = 15, where ω 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 ω, type of cosurfactant, and bacterial strains. PMID:25241843

  20. Synthesis, micellization behavior and alcohol induced amphipathic cellulose film of cellulose-based amphiphilic surfactant

    NASA Astrophysics Data System (ADS)

    Yang, Fang; Liu, Ya-nan; Yu, Jian-ling; Li, Hai-peng; Li, Gang

    2015-08-01

    This paper presented a novel preparation method of the cellulose-based amphiphilic surfactant, and the surfactant was used to prepare amphipathic cellulose membrane. The native cotton cellulose was tailored to cellulose segments in ionic liquid 1-butyl-3-methylimidazolium chloride. Then, the hydrophobic and hydrophilic modification of cellulose segments were carried out by esterification and graft polymerization of the ɛ-caprolactone (ɛ-CL) monomer onto the hydroxyl group of cellulose as well as sulphonation with sulfamic acid. The amphipathic cellulose membrane was made by cellulose-based amphiphilic surfactant cross-linking with glutaraldehyde. The molecular structure of amphipathic cellulose surfactant was confirmed by FT-IR, and its surface active properties were investigated by Wilhelmy plate method and Steady-state fluorescence probe method, respectively. Experimental results showed that cellulose-based amphiphilic surfactant caused low interfacial tension of 48.62 mN/m and its critical micelle concentration (cmc) value was 0.65 wt% when the grafting ratio of cellulose-g-PCL (poly-caprolactone) was 25.40%. The contact angle between a droplet of water and the surface of membrane was 90.84o, and the surface free energy of the alcohol induced cellulose membrane was 15.7 mJ/m2. This study may help increase using natural and biodegradable surface-activity materials with improved properties as surfactants.

  1. 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.

  2. Unique Phase Behaviors in the Gemini Surfactant/EAN Binary System: The Role of the Hydroxyl Group.

    PubMed

    Li, Qintang; Wang, Xudong; Yue, Xiu; Chen, Xiao

    2015-12-22

    The hydroxyl group in the spacer of a cationic Gemini surfactant (12-3OH-12) caused dramatic changes of the phase behaviors in a protic ionic liquid (EAN). Here, the effects of the hydroxyl group on micellization and lyotropic liquid crystal formation were investigated through the surface tension, small-angle X-ray scattering, polarized optical microscopy, and rheological measurements. With the hydroxyl group in the spacer, the critical micellization concentration of 12-3OH-12 was found to be lower than that of the homologue without hydroxyl (12-3-12) and the 12-3OH-12 molecules packed more densely at the air/EAN interface. It was then interesting to observe a coexistence of two separated phases at wide concentration and temperature ranges in this 12-3OH-12/EAN system. Such a micellar phase separation was rarely observed in the ionic surfactant binary system. With the increase of surfactant concentration, the reverse hexagonal and bicontinuous cubic phases appeared in sequence, whereas only a reverse hexagonal phase was found in 12-3-12/EAN system. But, the hexagonal phases formed with 12-3OH-12 exhibited lower viscoelasticity and thermostability than those observed in 12-3-12/EAN system. Such unique changes in phase behaviors of 12-3OH-12 were ascribed to their enhanced solvophilic interactions of 12-3OH-12 and relatively weak solvophobic interactions in EAN. PMID:26634877

  3. Shear-Induced Deformation of Surfactant Multilamellar Vesicles

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  4. 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.

  5. Maximizing the stability of pyrolysis oil/diesel fuel emulsions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several emulsions consisting of biomass pyrolysis oil (bio-oil) in diesel fuel were produced and analyzed for stability over time. An ultrasonic probe was used to generate microscopic droplets of bio-oil suspended in diesel fuel, and this emulsion was stabilized using surfactant chemicals. The most...

  6. 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

  7. Polymeric surfactants in disperse systems.

    PubMed

    Tadros, Tharwat

    2009-01-01

    This overview starts with a section on general classification of polymeric surfactants. Both homopolymers, block and graft copolymers are described. The solution properties of polymeric surfactants is described by using the Flory-Huggins theory. Particular attention is given to the effect of solvency of the medium for the polymer chains. The adsorption and conformation of homopolymers, block and graft copolymers at the solid/liquid interface is described. The theories of polymer adsorption and their predictions are briefly described. This is followed by a description of the experimental techniques that can be applied to study polymeric surfactant adsorption. Examples of adsorption isotherms of non-ionic polymeric surfactants are given. The effect of solvency on the adsorption amount is also described. Results for the adsorbed layer thickness of polymeric surfactants are given with particular attention to the effect of molecular weight. The interaction between particles containing adsorbed layers is described in terms of the unfavorable mixing of the stabilizing chains when these are in good solvent conditions. The entropic, volume restriction or elastic interaction that occurs on considerable overlap is also described. Combination of these two effects forms the basis of the theory of steric stabilization. The energy-distance curve produced with these sterically stabilized systems is described with particular attention of the effect of the ratio of adsorbed layer thickness to droplet radius. Examples of oil-in-water (O/W) and water-in-oil (W/O) emulsions stabilized with polymeric surfactants are given. Of particular interest is the O/W emulsions stabilized using hydrophobically modified inulin (INUTEC((R))SP1). The emulsions produced are highly stable against coalescence both in water and high electrolyte concentrations. This is accounted for by the multipoint attachment of the polymeric surfactant to the oil droplets with several alkyl groups and the strongly hydrated loops and tails of linear polyfructose. Evidence of this high stability was obtained from disjoining pressure measurements. Stabilization of suspensions using INUTEC((R))SP1 was described with particular reference to latexes that were prepared using emulsion polymerization. The high stability of the latexes is attributed to the strong adsorption of the polymeric surfactant on the particle surfaces and the enhanced steric stabilization produced by the strongly hydrated polyfructose loops and tails. Evidence for such high stability was obtained using Atomic Force Microscopy (AFM) measurements. The last part of the overview described the preparation and stabilization of nano-emulsions using INUTEC((R))SP1. In particular the polymeric surfactant was very effective in reducing Ostwald ripening as a result of its strong adsorption and the Gibbs elasticity produced by the polymeric surfactant. PMID:19041086

  8. Surfactant mixing rules applied to surfactant enhanced alkaline flooding

    SciTech Connect

    Taylor, K.C. )

    1992-01-01

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

  9. Evaluation the thermodynamic behavior of nonionic polyoxyethylene surfactants against temperature changes.

    PubMed

    Moghaddam, Hadi Mahmoudi; Dehghannoudeh, Gholamreza; Basir, Mohammad Zaman

    2016-03-01

    Micellization is the most important property of surface agents. It plays an important role in the manufacture of pharmaceutical products. The surfactants have many applications in industry, agriculture, mining and oil recovery with functional properties as wetting, foaming and emulsifier in pharmaceutical and cosmetic products. The micellization parameters of surfactants help the manufacture of pharmaceutical products to be appropriate and stable. Therefore, in this study, Polyoxyethylene lauryl ether (C12E23), Polyoxyethylene (10) cetyl ether (C16E10) and Polyoxyethylene (20) cetyl ether (C16E20) were chosen as the nonionic surfactants to examine the effect of temperature variation (10-80(°)C) on the Critical Micelle Concentration (CMC). The measurement of surface tension was done by a Du Nöuys ring method. The value of CMC was obtained from the surface tension vs. surfactant concentration curve. Since the temperature was increased, the CMC initially decreased and then increased for each surfactant because the formation of the hydrogen bond is harder in the high temperatures. The surface tension γCMC for all three surfactant solutions decreased monotonically as the temperature increased. δG(°)m, ΔH(°)m and ΔS°m as the thermodynamic parameters of micellization, were also estimated and analyzed. The ΔG(°)m was decreased (10-80(°)C) if the temperature was increased. The entropy and enthalpy correlation of micellization showed a significant linearity. For C12E23, C16E20 and C16 E10, the compensation temperature (Tc) was obtained 309.5, 313.2 and 314.4 K, respectively. The calculated thermodynamic parameters showed that the entropy influenced on the micellization process at lower temperature, but it affected by enthalpy when temperature was increased. PMID:27087077

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

    PubMed

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

    2009-01-01

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

  11. 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.

  12. 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.

  13. Enzymatically structured emulsions in simulated gastrointestinal environment: impact on interfacial proteolysis and diffusion in intestinal mucus.

    PubMed

    Macierzanka, Adam; Böttger, Franziska; Rigby, Neil M; Lille, Martina; Poutanen, Kaisa; Mills, E N Clare; Mackie, Alan R

    2012-12-18

    Fundamental knowledge of physicochemical interactions in the gastrointestinal environment is required in order to support rational designing of protein-stabilized colloidal food and pharmaceutical delivery systems with controlled behavior. In this paper, we report on the colloidal behavior of emulsions stabilized with the milk protein sodium caseinate (Na-Cas), and exposed to conditions simulating the human upper gastrointestinal tract. In particular, we looked at how the kinetics of proteolysis was affected by adsorption to an oil-water interface in emulsion and whether the proteolysis and the emulsion stability could be manipulated by enzymatic structuring of the interface. After cross-linking with the enzyme transglutaminase, the protein was digested with use of an in vitro model of gastro-duodenal proteolysis in the presence or absence of physiologically relevant surfactants (phosphatidylcholine, PC; bile salts, BS). Significant differences were found between the rates of digestion of Na-Cas cross-linked in emulsion (adsorbed protein) and in solution. In emulsion, the digestion of a population of polypeptides of M(r) ca. 50-100 kDa was significantly retarded through the gastric digestion. The persistent interfacial polypeptides maintained the original emulsion droplet size and prevented the system from phase separating. Rapid pepsinolysis of adsorbed, non-cross-linked Na-Cas and its displacement by PC led to emulsion destabilization. These results suggest that structuring of emulsions by enzymatic cross-linking of the interfacial protein may affect the phase behavior of emulsion in the stomach and the gastric digestion rate in vivo. Measurements of ζ-potential revealed that BS displaced the remaining protein from the oil droplets during the simulated duodenal phase of digestion. Diffusion of the postdigestion emulsion droplets through ex vivo porcine intestinal mucus was only significant in the presence of BS due to the high negative charge these biosurfactants imparted to the droplets. This implies that the electrostatic repulsion produced can prevent the droplets from being trapped by the mucus matrix and facilitate their transport across the small intestine mucosal barrier. PMID:23171215

  14. 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

  15. Crocin loaded nano-emulsions: Factors affecting emulsion properties in spontaneous emulsification.

    PubMed

    Mehrnia, Mohammad-Amin; Jafari, Seid-Mahdi; Makhmal-Zadeh, Behzad S; Maghsoudlou, Yahya

    2016-03-01

    Spontaneous emulsification may be used for encapsulating bioactive compounds in food and pharmaceutical industry. It has several advantages over high energy and other low energy methods including, protecting sensitive compounds against severe conditions of high energy method and its ability to minimize surfactant, removal of cosurfactant and thermal stability compared with other low energy methods. In this study, we examined possibility of encapsulating highly soluble crocin in W/O micro-emulsions using spontaneous method which further could be used for making double emulsions. Nonionic surfactants of Span 80 and polyglycerol polyricinoleate (PGPR) were used for making micro-emulsions that showed the high potential of PGPR for spontaneous method. Surfactant to water ratio (SWR%) was evaluated to find the highest amount of aqueous phase which can be dispersed in organic phase. Droplet size decreased by increasing SWR toward the SWR=100% which had the smallest droplet size and then increased at higher levels of surfactant. By increasing SWR, shear viscosity increased which showed the high effect of PGPR on rheological properties. This study shows in addition to W/O micro-emulsions, spontaneous method could be used for preparing stable O/W micro-emulsions. PMID:26708427

  16. Structure-Property Relationships in CO2-philic (Co)polymers: Phase Behavior, Self-Assembly, and Stabilization of Water/CO2 Emulsions.

    PubMed

    Girard, Etienne; Tassaing, Thierry; Marty, Jean-Daniel; Destarac, Mathias

    2016-04-13

    This Review provides comprehensive guidelines for the design of CO2-philic copolymers through an exhaustive and precise coverage of factors governing the solubility of different classes of polymers. Starting from computational calculations describing the interactions of CO2 with various functionalities, we describe the phase behavior in sc-CO2 of the main families of polymers reported in literature. The self-assembly of amphiphilic copolymers of controlled architecture in supercritical carbon dioxide and their use as stabilizers for water/carbon dioxide emulsions then are covered. The relationships between the structure of such materials and their behavior in solutions and at interfaces are systematically underlined throughout these sections. PMID:27014998

  17. Nonlinear Surface Dilatational Rheology and Foaming Behavior of Protein and Protein Fibrillar Aggregates in the Presence of Natural Surfactant.

    PubMed

    Wan, Zhili; Yang, Xiaoquan; Sagis, Leonard M C

    2016-04-19

    The surface and foaming properties of native soy glycinin (11S) and its heat-induced fibrillar aggregates, in the presence of natural surfactant steviol glycoside (STE), were investigated and compared at pH 7.0 to determine the impact of protein structure modification on protein-surfactant interfacial interactions. The adsorption at, and nonlinear dilatational rheological behavior of, the air-water interface were studied by combining drop shape analysis tensiometry, ellipsometry, and large-amplitude oscillatory dilatational rheology. Lissajous plots of surface pressure versus deformation were used to analyze the surface rheological response in terms of interfacial microstructure. The heat treatment generates a mixture of long fibrils and unconverted peptides. The presence of small peptides in 11S fibril samples resulted in a faster adsorption kinetics than that of native 11S. The addition of STE affected the adsorption of 11S significantly, whereas no apparent effect on the adsorption of the 11S fibril-peptide system was observed. The rheological response of interfaces stabilized by 11S-STE mixtures also differed significantly from the response for 11S fibril-peptide-STE mixtures. For 11S, the STE reduces the degree of strain hardening in extension and increases strain hardening in compression, suggesting the interfacial structure may change from a surface gel to a mixed phase of protein patches and STE domains. The foams generated from the mixtures displayed comparable foam stability to that of pure 11S. For 11S fibril-peptide mixtures STE only significantly affects the response in extension, where the degree of strain softening is decreased compared to the pure fibril-peptide system. The foam stability of the fibril-peptide system was significantly reduced by STE. These findings indicate that fibrillization of globular proteins could be a potential strategy to modify the complex surface and foaming behaviors of protein-surfactant mixtures. PMID:27043221

  18. Nanoscopic surfactant behavior of the porin MspA in aqueous media

    PubMed Central

    Wang, Hongwang; Shrestha, Tej B; Troyer, Deryl L

    2013-01-01

    Summary The mycobacterial porin MspA is one of the most stable channel proteins known to date. MspA forms vesicles at low concentrations in aqueous buffers. Evidence from dynamic light scattering, transmission electron microscopy and zeta-potential measurements by electrophoretic light scattering indicate that MspA behaves like a nanoscale surfactant. The extreme thermostability of MspA allows these investigations to be carried out at temperatures as high as 343 K, at which most other proteins would quickly denature. The principles of vesicle formation of MspA as a function of temperature and the underlying thermodynamic factors are discussed here. The results obtained provide crucial evidence in support of the hypothesis that, during vesicle formation, nanoscopic surfactant molecules, such as MspA, deviate from the principles underlined in classical surface chemistry. PMID:23766950

  19. Superamphiphilic nanocontainers based on the resorcinarene - Cationic surfactant system: Synergetic self-assembling behavior

    NASA Astrophysics Data System (ADS)

    Gaynanova, Gulnara A.; Bekmukhametova, Alina M.; Kashapov, Ruslan R.; Ziganshina, Albina Yu.; Zakharova, Lucia Ya.

    2016-05-01

    Self-organization in the mixed system based on water-soluble aminomethylated calix[4]arene with sulfonatoethyl groups at the lower rim and classical cationic surfactant cetyltrimethylammonium bromide has been studied by the methods of tensiometry, conductometry, spectrophotometry, dynamic and electrophoretic light scattering. The values of the critical association concentration, the size and zeta potential values, and the solubilization capacity of mixed aggregates toward the hydrophobic probe (Sudan I) were determined.

  20. Protein Fibrils Induce Emulsion Stabilization.

    PubMed

    Peng, Jinfeng; Simon, Joana Ralfas; Venema, Paul; van der Linden, Erik

    2016-03-01

    The behavior of an oil-in-water emulsion was studied in the presence of protein fibrils for a wide range of fibril concentrations by using rheology, diffusing wave spectroscopy, and confocal laser scanning microscopy. Results showed that above a minimum fibril concentration depletion flocculation occurred, leading to oil droplet aggregation and enhanced creaming of the emulsion. Upon further increasing the concentration of the protein fibrils, the emulsions were stabilized. In this stable regime both aggregates of droplets and single droplets are present, and these aggregates are smaller than the aggregates in the flocculated emulsion samples at the lower fibril concentrations. The size of the droplet aggregates in the stabilized emulsions is independent of fibril concentration. In addition, the droplet aggregation was reversible upon dilution both by a pH 2 HCl solution and by a fibril solution at the same concentration. The viscosity of the emulsions containing fibrils was comparable to that of the pure fibril solution. Neither fibril networks nor droplet gel networks were observed in our study. The stabilization mechanism of emulsions containing long protein fibrils at high protein fibril concentrations points toward the mechanism of a kinetic stabilization. PMID:26882086

  1. The coalescence stability of protein-stabilized emulsions estimated by analytical photo-centrifugation.

    PubMed

    Cheetangdee, Nopparat; Oki, Mariko; Fukada, Kazuhiro

    2011-01-01

    Various protein solutions were studied in order to quantify the emulsifying activity of proteins, and to explore oil-water interfacial tension, oil particle size analysis, and oil phase separation behaviors in protein-stabilized oil-in-water (O/W) emulsions. Three proteins, bovine serum albumin (BSA), β-lactoglobulin (β-lg), and β-casein (β-ca), were employed to disperse hexadecane in various pH and ionic strength solutions in a wide range of oil-water ratios. It was confirmed that the volume mean oil droplet diameter, d(43), changed depending on the oil content, the pH, the ionic strength, and the used protein. In a dilute protein solution (0.01 %) at pH 7, droplet size increased with oil content in so-called surfactant-poor regimes (e.g., above 5%, 10%, and 20% oil content for BSA, β-lg, and β-ca emulsion, respectively) but remained constant at ca. 10 mm, 6 mm, and 20 mm, respectively, in lower oil content surfactant-rich regimes. In surfactant-poor regimes, the most important factor determining the oil drop size was the threshold amount of protein adsorption onto the oil-water interface. In surfactant-rich regimes, on the other hand, it is suggested that drop size may be governed mainly by the mechanical strength of protein films covering the oil drops during emulsification, and this was quantified by the critical osmotic pressure, P(CR). In this study, the P(CR) was measured conveniently in the oil phase separation experiments for protein-stabilized emulsions using analytical photo-centrifugal apparatus. The correlation between the P(CR) and oil droplet size prepared by emulsification at different pH and ionic strength media is discussed. PMID:21768743

  2. Liquid crystal Janus emulsion droplets: preparation, tumbling, and swimming.

    PubMed

    Jeong, Joonwoo; Gross, Adam; Wei, Wei-Shao; Tu, Fuquan; Lee, Daeyeon; Collings, Peter J; Yodh, A G

    2015-09-14

    This study introduces liquid crystal (LC) Janus droplets. We describe a process for the preparation of these droplets, which consist of nematic LC and polymer compartments. The process employs solvent-induced phase separation in emulsion droplets generated by microfluidics. The droplet morphology was systematically investigated and demonstrated to be sensitive to the surfactant concentration in the background phase, the compartment volume ratio, and the possible coalescence of multiple Janus droplets. Interestingly, the combination of a polymer and an anisotropic LC introduces new functionalities into Janus droplets, and these properties lead to unusual dynamical behaviors. The different densities and solubilities of the two compartments produce gravity-induced alignment, tumbling, and directional self-propelled motion of Janus droplets. LC Janus droplets with remarkable optical properties and dynamical behaviors thus offer new avenues for applications of Janus colloids and active soft matter. PMID:26171829

  3. 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

  4. 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.

  5. 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.

  6. Evaluation of the Transwell System for Characterization of Dissolution Behavior of Inhalation Drugs: Effects of Membrane and Surfactant.

    PubMed

    Rohrschneider, Marc; Bhagwat, Sharvari; Krampe, Raphael; Michler, Victoria; Breitkreutz, Jörg; Hochhaus, Günther

    2015-08-01

    Assessing the dissolution behavior of orally inhaled drug products (OIDs) has been proposed as an additional in vitro test for the characterization of innovator and generic drug development. A number of suggested dissolution methods (e.g., commercially available Transwell or Franz cell systems) have in common a membrane which provides the separation between the donor compartment, containing nondissolved drug particles, and an acceptor (sampling) compartment into which dissolved drug will diffuse. The goal of this study was to identify and overcome potential pitfalls associated with such dissolution systems using the inhaled corticosteroids (ICS), viz., budesonide, ciclesonide, and fluticasone propionate, as model compounds. A respirable fraction (generally stage 4 of a humidity, flow, and temperature controlled Andersen Cascade Impactor (ACI) or a Next Generation Impactor (NGI)) was collected for the tested MDIs. The dissolution behavior of these fractions was assessed employing the original and an adapted Transwell system using dissolution media which did or did not contain surfactant (0.5% sodium dodecyl sulfate). The rate with which the ICS transferred from the donor to the acceptor compartment was assessed by HPLC. Only a modified system that incorporated faster equilibrating membranes instead of the original 0.4 μm Transwell membrane resulted in dissolution and not diffusion being the rate-limiting step for the transfer of drug from the donor to the acceptor compartment. Experiments evaluating the nature of the dissolution media suggested that the presence of a surfactant (e.g., 0.5% SDS) is essential to obtain rank order of dissolution rates (e.g., for budesonide, fluticasone propionate, and ciclesonide) that is in agreement with absorption rates of these ICS obtained in studies of human pharmacokinetics. Using the optimized procedure, the in vitro dissolution behavior of budesonide, ciclesonide, and fluticasone propionate agreed approximately with descriptors of in vivo absorption. The optimized procedure, using membranes with increased permeability and surfactant containing dissolution medium, represents a good starting point to further evaluate in vitro/in vivo correlations. PMID:26091361

  7. 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.

  8. Thermodynamic characterization of the interaction behavior of a hydrophobically modified polyelectrolyte and oppositely charged surfactants in aqueous solution: effect of surfactant alkyl chain length.

    PubMed

    Bai, Guangyue; Nichifor, Marieta; Lopes, António; Bastos, Margarida

    2005-01-13

    We have used a precision isothermal titration microcalorimeter (ITC) to measure the enthalpy curves for the interaction of a hydrophobically modified polyelectrolyte (D40OCT30) with oppositely charged surfactants (SC(n)S) in aqueous solution. D40OCT30 is a newly synthesized polymer based on dextran having pendant N-(2-hydroxypropyl)-N,N-dimethyl-N-octylammonium chloride groups randomly distributed along the polymer backbone with degree of substitution of 28.1%. The employed anionic surfactants are sodium octyl sulfate (SC(8)S) and sodium tetradecyl sulfate (SC(14)S). Microcalorimetric results along with turbidity and kinematic viscosity measurements demonstrate systematically the thermodynamic characterization of the interaction of D40OCT30/SC(n)S. A three-dimensional diagram with the derived phase boundaries is drawn to describe the effect of the alkyl chain length of surfactant and of the ratio between surfactant and pendant groups on the interaction. A more complete picture of the interaction mechanism for D40OCT30/SC(n)S systems is proposed here. PMID:16851043

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

    PubMed

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

    2006-05-15

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

  10. 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

  11. Optimization of folic acid nano-emulsification and encapsulation by maltodextrin-whey protein double emulsions.

    PubMed

    Assadpour, Elham; Maghsoudlou, Yahya; Jafari, Seid-Mahdi; Ghorbani, Mohammad; Aalami, Mehran

    2016-05-01

    Due to susceptibility of folic acid like many other vitamins to environmental and processing conditions, it is necessary to protect it by highly efficient methods such as micro/nano-encapsulation. Our aim was to prepare and optimize real water in oil nano-emulsions containing folic acid by a low energy (spontaneous) emulsification technique so that the final product could be encapsulated within maltodextrin-whey protein double emulsions. A non ionic surfactant (Span 80) was used for making nano-emulsions at three dispersed phase/surfactant ratios of 0.2, 0.6, and 1.0. Folic acid content was 1.0, 2.0, and 3.0mg/mL of dispersed phase by a volume fraction of 5.0, 8.5, and 12%. The final optimum nano-emulsion formulation with 12% dispersed phase, a water to surfactant ratio of 0.9 and folic acid content of 3mg/mL in dispersed phase was encapsulated within maltodextrin-whey protein double emulsions. It was found that the emulsification time for preparing nano-emulsions was between 4 to 16h based on formulation variables. Droplet size decreased at higher surfactant contents and final nano-emulsions had a droplet size<100nm. Shear viscosity was higher for those formulations containing more surfactant. Our results revealed that spontaneous method could be used successfully for preparing stable W/O nano-emulsions containing folic acid. PMID:26806649

  12. Phase behavior and interfacial properties of a switchable ethoxylated amine surfactant at high temperature and effects on CO2-in-water foams.

    PubMed

    Chen, Yunshen; Elhag, Amro S; Reddy, Prathima P; Chen, Hao; Cui, Leyu; Worthen, Andrew J; Ma, Kun; Quintanilla, Heriberto; Noguera, Jose A; Hirasaki, George J; Nguyen, Quoc P; Biswal, Sibani L; Johnston, Keith P

    2016-05-15

    The interfacial properties for surfactants at the supercritical CO2-water (C-W) interface at temperatures above 80°C have very rarely been reported given limitations in surfactant solubility and chemical stability. These limitations, along with the weak solvent strength of CO2, make it challenging to design surfactants that adsorb at the C-W interface, despite the interest in CO2-in-water (C/W) foams (also referred to as macroemulsions). Herein, we examine the thermodynamic, interfacial and rheological properties of the surfactant C12-14N(EO)2 in systems containing brine and/or supercritical CO2 at elevated temperatures and pressures. Because the surfactant is switchable from the nonionic state to the protonated cationic state as the pH is lowered over a wide range in temperature, it is readily soluble in brine in the cationic state below pH 5.5, even up to 120°C, and also in supercritical CO2 in the nonionic state. As a consequence of the affinity for both phases, the surfactant adsorption at the CO2-water interface was high, with an area of 207Å(2)/molecule. Remarkably, the surfactant lowered the interfacial tension (IFT) down to ∼5mN/m at 120°C and 3400 psia (23MPa), despite the low CO2 density of 0.48g/ml, indicating sufficient solvation of the surfactant tails. The phase behavior and interfacial properties of the surfactant in the cationic form were favorable for the formation and stabilization of bulk C/W foam at high temperature and high salinity. Additionally, in a 1.2 Darcy glass bead pack at 120°C, a very high foam apparent viscosity of 146 cP was observed at low interstitial velocities given the low degree of shear thinning. For a calcium carbonate pack, C/W foam was formed upon addition of Ca(2+) and Mg(2+) in the feed brine to keep the pH below 4, by the common ion effect, in order to sufficiently protonate the surfactant. The ability to form C/W foams at high temperatures is of interest for a variety of applications in chemical synthesis, separations, materials science, and subsurface energy production. PMID:26930543

  13. 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

  14. Dynamics of oppositely charged emulsion droplets

    NASA Astrophysics Data System (ADS)

    Liu, Zhou; Wyss, Hans M.; Fernandez-Nieves, Alberto; Shum, Ho Cheung

    2015-08-01

    We study the dynamics of two pinned droplets under the influence of an applied electric stress. We find that at a sufficiently strong field, this stress is sufficient to induce contact of the droplets. Interestingly, upon such contact, the dynamic behavior sensitively depends on the separation distance between the droplets. Besides the classical "coalescence" regime, we identify two other dynamic regimes: "fuse-and-split" and "periodic non-coalescence." In the "fuse-and-split" regime, the droplets first fuse to form a jet, which subsequently breaks up into two droplets. In the "periodic non-coalescence" regime, the droplets contact and bounce away periodically without coalescence. Further analysis indicates that while the electric stress stretches the droplets into shapes that depend on the initial droplet separation, the surface tension stress dominates over the electric stress as soon as the droplets touch. We show that the shapes of the contacting droplets determine their subsequent dynamics. Our work provides a rationale for understanding the interplay between surface tension and electric stresses that govern the behavior of charged droplets and could inspire new methods for characterizing emulsion stability and surfactant performance.

  15. 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.

  16. Synthesis of Fluorosurfactants for Emulsion-Based Biological Applications

    PubMed Central

    2015-01-01

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

  17. Reversible assembly of pH responsive branched copolymer-stabilised emulsion via electrostatic forces.

    PubMed

    Maçon, Anthony L B; Rehman, Saif Ur; Bell, Robert V; Weaver, Jonathan V M

    2016-01-01

    The judicious compositional and structural design of a branched co-polymeric surfactant allows for the production of highly stable oil in water emulsion droplets with reversible electrostatic aggregation behaviour. PMID:26503757

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

    PubMed

    Piculell, Lennart

    2013-08-20

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

  19. 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.

  20. Optical diffusers based on silicone emulsions

    NASA Astrophysics Data System (ADS)

    Wang, Jui-Hao; Lien, Shui-Yang; Ho, Jeng-Rong; Shih, Teng-Kai; Chen, Chia-Fu; Chen, Chien-Chung; Whang, Wha-Tzong

    2009-12-01

    The present study provides an experimental approach for fabricating optical diffuser films based on silicone emulsions. The silicone emulsion consisting of silicone polymer (Sylgard 184) and NaCl aq. solution was used as the optical material of diffusers, wherein NaCl aq. solution was severed as surfactant to stabilize the emulsions. After stirring mechanically, microscaled water drop with various sizes distributed randomly in silicone polymer, wherein water drop was used as scattering diffusion particles. To modulate the volume of NaCl aq. solution, the diffusing performance of diffusers could be change by different amount drop particles. Thereafter, an optical examination was carried out to characterize optical properties, transmittance, and light diffusivity of volumetric diffuser films.

  1. Lung surfactant.

    PubMed Central

    Rooney, S A

    1984-01-01

    Aspects of pulmonary surfactant are reviewed from a biochemical perspective. The major emphasis is on the lipid components of surfactant. Topics reviewed include surfactant composition, cellular and subcellular sites as well as pathways of biosynthesis of phosphatidylcholine, disaturated phosphatidylcholine and phosphatidylglycerol. The surfactant system in the developing fetus and neonate is considered in terms of phospholipid content and composition, rates of precursor incorporation, activities of individual enzymes of phospholipid synthesis and glycogen content and metabolism. The influence of the following hormones and other factors on lung maturation and surfactant production is discussed: glucocorticoids, thyroid hormone, estrogen, prolactin, cyclic AMP, beta-adrenergic and cholinergic agonists, prostaglandins and growth factors. The influence of maternal diabetes, fetal sex, stress and labor are also considered. Nonphysiologic and toxic agents which influence surfactant in the fetus, newborn and adult are reviewed. PMID:6145585

  2. 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.

  3. A Surfactant Bridge Model for the Nonlinear Electrorheological Effects of Surfactant-Activated ER Suspensions.

    PubMed

    Kim, Young Dae

    2001-04-15

    In surfactant-activated electrorheological (ER) suspensions it is observed that the ER response shows linear ER behavior (F~E(2)) at small surfactant concentrations and nonlinear ER behavior (F~E(n), n approximately 1) at large surfactant concentrations. Here, a surfactant bridge model is developed to explain the nonlinear ER behavior of surfactant-activated ER suspensions. The model shows that the formation and size of a surfactant bridge depend on various variables, especially the electric field strength, the surfactant surface tension, and the initially adsorbed amount of surfactants on particles. The predicted dependence of the formation and size of a surfactant bridge on the electric field strength and the initially adsorbed amount of surfactants is consistent with the observations. Also, the model indicates that there is a critical minimum electric field E(crit) for the formation of a surfactant bridge, and the estimated E(crit) shows good agreement with the observations. The force acting between particles is composed of the electrostatic force and force associated with surface tension. However, it is found that the contribution of the force associated with surface tension can be ignored and the electrostatic force is dominant regardless of the formation of surfactant bridges between particles. When surfactant bridges are formed between particles, the predicted force shows nonlinear ER behavior (F~E(n), n approximately 1), consistent with the observed nonlinear ER behavior at large surfactant concentrations. When no surfactant bridge is formed, the predicted force is proportional to the electric field squared (F~E(2)), consistent with the interfacial polarization. The model can successfully predict the nonlinear ER behavior at large surfactant concentrations, confirming that the nonlinear ER behavior of surfactant-activated ER suspensions arises from the observed formation of surfactant bridges between particles. Copyright 2001 Academic Press. PMID:11401368

  4. Emulsions with unique properties from proteins as emulsifiers.

    PubMed

    Hoffmann, H; Reger, M

    2014-03-01

    Many proteins are surface active molecules and form stable emulsions. In these emulsions, the protein covered oil droplets behave as sticky droplets even when they are ionically charged. As a result of the stickiness of the droplets the emulsions have gel-like properties. The stickiness is due to the multipolar nature of the proteins in contrast to the bipolar nature of surfactants or other amphiphilic compounds that form emulsions with repulsive droplets. Stable emulsions are also formed from particles like clays to which proteins are adsorbed. These hybrid compounds form even more stable emulsions with stronger elastic properties than clays and proteins on their own. These so called pickering emulsions have paste-like properties and do not flow. The scaffolding network of the crosslinked protein bilayers on the droplets is so strong that both the water and the oil can be removed from the emulsions by freeze drying without collapse of the scaffold. The resulting sponge can be used again for the uptake of both water and oil. Emulsions which are prepared from different proteins differ mainly in their elastic properties. PMID:24161225

  5. Extension of the surfactant bridge model for the electrorheological effects of surfactant-activated suspensions.

    PubMed

    Kim, Young Dae; Nam, Suk Woo

    2004-01-01

    Surfactants influence the electrorheological (ER) response in two ways. At low surfactant concentrations, they enhance the ER response by enhancing the particle polarizability; at high concentrations, the response degrades (nonlinear ER response). The nonlinear ER behavior arises from the formation of surfactant bridges between the particles at high surfactant concentrations. A surfactant bridge model was introduced to explain the nonlinear behavior (tau0 proportional to En, n approximately 1) of surfactant-activated ER suspensions when surfactant bridges were formed between the particles. Here, the surfactant bridge model is extended for the prediction of both the linear and nonlinear ER behaviors of surfactant-activated ER suspensions over the low and high surfactant concentrations (for Brij 30, from 0 to 7 wt%), regardless of the formation of surfactant bridges between the particles. For 20 wt% neutral alumina suspensions in silicone oil activated by Brij 30, the predicted ER behaviors show almost the same Brij 30 concentration and electric field strength dependence. It predicts the linear E2 dependence of the ER response at low surfactant concentrations and the nonlinear ER behavior at high surfactant concentrations. Also, the estimated yield stresses show fairly good agreement with the experimental data. PMID:14651914

  6. 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

  7. 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

  8. High acyl gellan as an emulsion stabilizer.

    PubMed

    Vilela, Joice Aline Pires; da Cunha, Rosiane Lopes

    2016-03-30

    High acyl gellan (0.01-0.2% w/w) was used as stabilizer in oil in water emulsions containing 30% (w/w) of sunflower oil and prepared under different process conditions. Stable emulsions to phase separation could be obtained using high acyl gellan (HA) content above 0.05% (w/w), while low acyl gellan (LA) prepared at the same conditions could not stabilize emulsions. Emulsions properties depended on the process used to mix the oil and gellan dispersion since high pressure homogenization favored stabilization while very high energy density applied by ultrasound led to systems destabilization. Emulsions prepared using high pressure homogenization showed zeta potential values ranging from -50 up to -59 mV, suggesting that electrostatic repulsion could be contributing to the systems stability. Rheological properties of continuous phase were also responsible for emulsions stabilization, since HA gellan dispersions showed high viscosity and gel-like behavior. The high viscosity of the continuous phase could be associated to the presence of high acyl gellan microgels/aggregates. Disentanglement of these aggregates performed by ultrasound strongly decreased the viscosity and consequently affected the emulsions behavior, reducing the stability to phase separation. PMID:26794954

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

    PubMed

    Alam, Mohammad Mydul; Aramaki, Kenji

    2008-11-01

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

  10. Emulsion design to improve the delivery of functional lipophilic components.

    PubMed

    McClements, David Julian

    2010-01-01

    The food industry has used emulsion science and technology for many years to create a diverse range of food products, such as milk, cream, soft drinks, nutritional beverages, dressings, mayonnaise, sauces, dips, deserts, ice cream, margarine, and butter. The majority of these food products are conventional oil-in-water (O/W) or water-in-oil (W/O) type emulsions. Recently, there has been increasing interest within the food industry in either improving or extending the functional performance of foods using novel structured emulsions. This article reviews recent developments in the creation of structured emulsions that could be used by the food and other industries, including nanoemulsions, multiple emulsions, multilayer emulsions, solid lipid particles, and filled hydrogel particles. These structured emulsions can be produced from food-grade [generally recognized as safe (GRAS)] ingredients (e.g., lipids, proteins, polysaccharides, surfactants, and minerals), using simple processing operations (e.g., mixing, homogenizing, and thermal processing). The structure, production, performance, and potential applications of each type of structured emulsion system are discussed. PMID:22129337

  11. Recent Emulsion Technologies

    SciTech Connect

    Ariga, A.

    2011-10-06

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

  12. Interaction of nonionic surfactant AEO9 with ionic surfactants*

    PubMed Central

    Zhang, Zhi-guo; Yin, Hong

    2005-01-01

    The interaction in two mixtures of a nonionic surfactant AEO9 (C12H25O(CH2CH2O)9H) and different ionic surfactants was investigated. The two mixtures were AEO9/sodium dodecyl sulfate (SDS) and AEO9/cetyltrimethylammonium bromide (CTAB) at molar fraction of AEO9, α AEO9=0.5. The surface properties of the surfactants, critical micelle concentration (CMC), effectiveness of surface tension reduction (γ CMC), maximum surface excess concentration (Γ max) and minimum area per molecule at the air/solution interface (A min) were determined for both individual surfactants and their mixtures. The significant deviations from ideal behavior (attractive interactions) of the nonionic/ionic surfactant mixtures were determined. Mixtures of both AEO9/SDS and AEO9/CTAB exhibited synergism in surface tension reduction efficiency and mixed micelle formation, but neither exhibited synergism in surface tension reduction effectiveness. PMID:15909351

  13. Nonionic surfactant and interfacial structure impact crystallinity and stability of β-carotene loaded lipid nanodispersions.

    PubMed

    Nik, Amir Malaki; Langmaid, Sarah; Wright, Amanda J

    2012-04-25

    The stability, crystallization, and melting behavior of canola stearin (CaSt) solid lipid nanoparticle dispersions (SLN) and canola oil-in-water emulsions (COE) with 10 wt % Poloxamer 188 (P188) or Tween 20 (T20) with and without 0.1 wt % β-carotene (BC) were investigated. Particles or droplets with diameters in the range of 115 nm were formed and stable for up to 90 days at 4 or 20 °C. Polymorphism was affected by surfactant type; that is, only β versus both β' and β were observed for the P188 and T20 SLN, respectively. According to Cryo-TEM, the emulsions and SLN were spherical versus platelet-like structures, respectively, with differences observed between SLN with P188 or T20. More surfactant was interfacially adsorbed in the SLN versus COE. Incorporation of BC at 0.1 wt % had no impact on SLN or COE size, polymorphism, or melting behavior. Less BC degradation was observed for the SLN versus COE and during storage at 4 versus 20 °C (p < 0.05). PMID:22401532

  14. Double emulsions for the compatibilization of hydrophilic nanocellulose with non-polar polymers and validation in the synthesis of composite fibers.

    PubMed

    Carrillo, Carlos A; Nypelö, Tiina; Rojas, Orlando J

    2016-03-14

    A route for the compatibilization of aqueous dispersions of cellulose nanofibrils (CNFs) with a non-polar polymer matrix is proposed to overcome a major challenge in CNF-based material synthesis. Non-ionic surfactants were used in CNF aqueous dispersions equilibrated with an organic phase (for demonstration, a polystyrene solution, PS, was used). Stable water-in-oil-in-water (W/O/W) double emulsions were produced as a result of the compromise between composition and formulation variables. Most remarkably, the proposed route for CNF integration with hydrophobic polymers removed the need for drying or solvent-exchange of the CNF aqueous dispersion prior to processing. The rheological behavior of the double emulsions showed strong shear thinning behavior and facilitated CNF-PS co-mixing in solid nanofibers upon electrospinning. The morphology and thermal properties of the resultant nanofibers revealed that CNFs were efficiently integrated in the hydrophobic matrix which was consistent with the high interfacial area of the precursor double emulsion. In addition, the morphology and quality of the composite nanofibers can be controlled by the conductivity (ionic strength) of the CNF dispersion. Overall, double emulsion systems are proposed as a novel, efficient and scalable platform for CNF co-processing with non-polar systems and they open up the possibility for the redispersion of CNFs after removal of the organic phase. PMID:26876673

  15. Static quasi-2D emulsion as a granular system

    NASA Astrophysics Data System (ADS)

    Wu, Rui; Orellana, Carlos; Hong, Xia; Desmond, Kenneth; Weeks, Eric

    2014-03-01

    We study the forces between emulsion droplets and the properties of force chains in a static oil-in-water emulsion system near jamming. The emulsion is confined between two parallel glass plates in order to construct a quasi-2D system. Quasi-2D emulsion systems are somewhat analogous to 2D granular disks, except for the absence of static friction between the droplets. We focus on samples at an area fraction ϕ that is higher than the jamming point, ϕc, and test the robustness of the power law dependence of pressure and the contact numbers on ϕ -ϕc . Specifically, we vary the surface tension by adding surfactants in the water, and examine the power law relationship under such variations. We also compare our result to simulations as well as established experimental results of true granular systems.

  16. Solubilization of octane in cationic surfactant-anionic polymer complexes: effect of polymer concentration and temperature.

    PubMed

    Zhang, Hui; Deng, Lingli; Zeeb, Benjamin; Weiss, Jochen

    2015-07-15

    Polymers may alter the ability of oppositely charged surfactant micelles to solubilize hydrophobic molecules depending on surfactant-polymer interactions. This study was conducted to investigate the effects of polymer concentration and temperature on the solubilization thermodynamics of an octane oil-in-water emulsion in mixtures of an anionic polymer (carboxymethyl cellulose) and cationic cetyltrimethylammonium bromide (CTAB) surfactant micelles using isothermal titration calorimetry (ITC). Results showed that the CTAB binding capacity of carboxymethyl cellulose increased with increasing temperature from 301 to 323 K, and correspondingly the thermodynamic behavior of octane solubilization in CTAB micelles, either in the absence or presence of polymer, was found to depend on temperature. The addition of carboxymethyl cellulose caused the solubilization in CTAB micelles to be less endothermic, and increased the solubilization capacity. Based on the phase separation model, the solubilization was suggested to be mainly driven by enthalpy gains. Results suggest that increasing concentrations of the anionic polymer gave rise to a larger Gibbs energy decrease and a larger unfavorable entropy increase for octane solubilization in cationic surfactant micelles. PMID:25841059

  17. Solubilization of octane in cationic surfactant-anionic polymer complexes: Effect of ionic strength.

    PubMed

    Zhang, Hui; Deng, Lingli; Sun, Ping; Que, Fei; Weiss, Jochen

    2016-01-01

    Polymers may alter the ability of oppositely charged surfactant micelles to solubilize hydrophobic molecules depending on surfactant-polymer interactions. This study was conducted to investigate the effect of ionic strength on the solubilization thermodynamics of an octane oil-in-water emulsion in mixtures of an anionic polymer (carboxymethyl cellulose) and cationic cetyltrimethylammonium bromide (CTAB) surfactant micelles using isothermal titration calorimetry (ITC). Results indicated that the CTAB binding capacity of carboxymethyl cellulose increased with increasing NaCl concentrations up to 100 mM, and the thermodynamic behavior of octane solubilization in CTAB micelles, either in the absence or presence of polymer, was found to have a strong dependence on ionic strength. The increasing ionic strength caused the solubilization in CTAB micelles to be less endothermic or even exothermic, but increased the solubilization capacity. Based on the phase separation model, the solubilization was suggested to be driven by enthalpy. It is indicated that increasing ionic strength gave rise to a larger Gibbs energy decrease but a smaller unfavorable entropy increase for octane solubilization in cationic surfactant micelles. PMID:26397914

  18. 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).

  19. Surface tension and adsorption behavior of mixtures of diacyl glycerol arginine-based surfactants with DPPC and DMPC phospholipids.

    TOXLINE Toxicology Bibliographic Information

    Lozano N; Pinazo A; Pons R; Pérez L; Franses EI

    2009-11-01

    The binary surface interactions of some novel cationic diacyl glycerol arginine-based surfactants with model phospholipids, which are often used as model membrane components, are studied at 25 degrees C in aqueous solutions of 0.1M sodium chloride. The surfactants are 1,2-dimyristoyl-rac-glycero-3-O-(N(alpha)-acetyl-L-arginine) hydrochloride (1414RAc) and 1,2-dilauroyl-rac-glycero-3-O-(N(alpha)-acetyl-L-arginine) hydrochloride (1212RAc), and they are important as potential antimicrobial agents which are biodegradable and with less toxicity than other cationic surfactants. The phospholipids are 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC). The equilibrium and dynamic surface tension of each surfactant, each phospholipid, and some of their binary mixtures are studied using the bubble surfactometry method at constant area or pulsating area conditions. In addition, the surface densities of pure and mixed monolayers of these compounds at the air/water interface are probed with infrared reflection-absorption spectroscopy (IRRAS). Steady state and dynamic surface tension synergism, or antisynergism in one case, and synergistic adsorption effects are detected for the mixed dispersions studied. The enhanced adsorption detected with IRRAS, and the enhanced dynamic and steady state surface tension lowering indicate strong miscibility and net attractive interactions between the compounds in the adsorbed mixed monolayers.

  20. Gemini Surfactants.

    PubMed

    Menger; Keiper

    2000-06-01

    How easy it is to dismiss the humdrum surfactant! After all, its structure is unglamorous by present-day norms. And the surfactant has been entrenched in so many areas of commerce for so many decades that its chemistry might seem old and tired. The purpose of this review is to persuade the reader otherwise, all the while focusing on a remarkable new surfactant, the gemini. Geminis, the common name for "bis-surfactants", can self-assemble at concentrations almost a hundredfold lower than for corresponding conventional surfactants. Surface activity can be improved a thousandfold. Geminis have already shown promise in skin care, antibacterial regimens, construction of high-porosity materials, analytical separations, and solubilization processes. Scores of patents dealing with geminis have appeared in the last few years. Indeed, geminis might well turn out, in the opinion of some, to be more useful to "l'homme de la rue" than crown ethers or fullerenes. This review delves into such topics as synthesis, critical micellization concentration, aggregate size and shape, gels, vesicles, and films. The information comes from scientists all over the world; one might say that gemini research is bathed in a continuous sunlight or summer. No prior knowledge of colloid chemistry is presupposed in this article. PMID:10940980

  1. Water-in-Crude Oil Emulsions: Its Stabilization and Demulsification

    NASA Astrophysics Data System (ADS)

    Nour, Abdurahman H.; Mohd. Yunus, R.; Anwaruddin, H.

    Traditional ways of breaking emulsions using heat and chemicals are disadvantageous from both economic and environmental perspectives. In this research, the potentials of microwave technology in demulsification of water-in-crude oil emulsions are investigated. The study began with some characterization studies to provide understandings of fundamental issues such as formation, formulation and breaking of emulsions by both chemical and microwave approaches. The aim was to obtain optimized operating conditions as well as fundamental understanding of water-in-oil emulsion stability upon which further developments on demulsification processes could be developed. It was found that emulsion stability was related to some parameters such as, the surfactant concentration, water content, temperature and agitation speed. Experimental results found that microwave radiation method can enhance the demulsification of water-in-oil emulsions in a very short time compared to the conventional heating methods. The results obtained in this study have exposed the capability of microwave technology in demulsification of water-in-oil emulsion. 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.

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

    SciTech Connect

    Grolitzer, M. A.

    1985-11-12

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

  3. 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.

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

    PubMed

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

    2012-05-22

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

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

    PubMed

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

    2012-12-15

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

  6. Phase behavior, small-angle neutron scattering and rheology of ternary nonionic surfactant-oil-water systems: a comparison of oils.

    PubMed

    Tabor, Rico F; Zaveer, Md Imran; Dagastine, Raymond R; Grillo, Isabelle; Garvey, Christopher J

    2013-03-19

    The phase behavior of the nonionic surfactant Triton X-100 (polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether) was studied in two three-component systems: Triton-water-p-xylene and Triton-water-trichloroethylene. It was found that the aromatic solvent was able to produce monophasic soft matter systems at a significantly greater range of compositions. The structural characteristics of the phases generated were analyzed by small-angle neutron scattering, showing evidence for microemulsion, lamellar, and reverse-microemulsion phases. In addition, for the Triton-water-p-xylene system, an L3 "sponge" phase was found in a water-rich region of the phase diagram and the properties of this were examined using rheological measurements. The differences in phase behavior are discussed in light of the solvation properties of the surfactant in the different solvents studied. Most notably, xylene appears to favor phases with low-curvature interfaces, suggesting preferential solvation of the central phenyl group of Triton. PMID:23418937

  7. Microemulsion versus emulsion as effective carrier of hydroxytyrosol.

    PubMed

    Chatzidaki, Maria D; Arik, Nehir; Monteil, Julien; Papadimitriou, Vassiliki; Leal-Calderon, Fernando; Xenakis, Aristotelis

    2016-01-01

    Two edible Water-in-Oil (W/O) dispersions, an emulsion that remains kinetically stable and a microemulsion which is spontaneously formed, transparent and thermodynamically stable, were developed for potential use as functional foods, due to their ability to be considered as matrices to encapsulate biologically active hydrophilic molecules. Both systems contained Medium Chain Triglycerides (MCT) as the continuous phase and were used as carriers of Hydroxytyrosol (HT), a hydrophilic antioxidant of olive oil. A low energy input fabrication process of the emulsion was implemented. The obtained emulsion contained 1.3% (w/w) of surfactants and 5% (w/w) aqueous phase. The spontaneously formed microemulsion contained 4.9% (w/w) of surfactants and 2% (w/w) aqueous phase. A comparative study in terms of structural characterization of the systems in the absence and presence of HT was carried out. Particle size distribution obtained by Dynamic Light Scattering (DLS) technique and interfacial properties of the surfactants' layer, examined by Electron Paramagnetic Resonance (EPR) spectroscopy indicated the involvement of HT in the surfactant membrane. Finally, the proposed systems were studied for the scavenging activity of the encapsulated antioxidant toward galvinoxyl stable free radical showing a high scavenging activity of HT in both systems. PMID:25999235

  8. Thermodynamically Stable Pickering Emulsions Stabilized by Janus Dumbbells

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  9. 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.

  10. Study of O/W micro- and nano-emulsions based on propylene glycol diester as a vehicle for geranic acid.

    PubMed

    Jaworska, Małgorzata; Sikora, Elżbieta; Ogonowski, Jan; Konieczna, Monika

    2015-01-01

    Nano- and microemulsions containing as the oil phase caprylic/capric propylene glycol diesters (Crodamol PC) were investigated as potential vehicle for controlled release of geranic acid. The influence of emulsifiers and co-surfactants on stability of the emulsions was investigated. Different kind of polysorbates (ethoxylated esters of sorbitan and fatty acids) were applied as the emulsifiers. The short-chain alcohols (ethanol, 1-propanol, 1-butanol) were used as co-surfactants. The emulsions were prepared at ambient temperature (25°C), by the phase inversion composition method (PIC). The stable O/W high dispersed emulsion systems based on Crodamol PC, of mean droplets size less than 200 nm, were prepared. Microemulsions stabilized by the mixture of Polisorbat 80 and 1-butanol were characterized by the largest degree of dispersion (137 nm) and the lowest PDI value (0.094), at surfactant/co-surfactant: oil weight ratio 90:10. The stable nano-emulsion (mean droplet size of 33 nm) was obtained for surfactant: oil (S:O) weight ratio 90:10, without co-surfactant addition. This nano-emulsion was chosen to release studies. The obtained results showed that the prepared stable nano-emulsion can be used as a carrier for controlled release of geranic acid. The active substance release from the nano-emulsion and the oil solution, after 24 hours was 22%. PMID:25856560

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

    SciTech Connect

    Salathiel, W. M.

    1985-05-14

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

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

    SciTech Connect

    Zhang Ying; Jin Chao

    2011-01-15

    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{sub 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. -- Graphical abstract: The nonionic emulsion synthesis allows rapid crystallization and morphological adjustment of zeolite ZSM-5 compared with the conventional hydrothermal synthesis. Display Omitted

  13. 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.

  14. 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

  15. To Model Chemical Reactivity in Heterogeneous Emulsions, Think Homogeneous Microemulsions.

    PubMed

    Bravo-Daz, Carlos; Romsted, Laurence Stuart; Liu, Changyao; Losada-Barreiro, Sonia; Pastoriza-Gallego, Maria Jos; Gao, Xiang; Gu, Qing; Krishnan, Gunaseelan; Snchez-Paz, Vernica; Zhang, Yongliang; Dar, Aijaz Ahmad

    2015-08-25

    Two important and unsolved problems in the food industry and also fundamental questions in colloid chemistry are how to measure molecular distributions, especially antioxidants (AOs), and how to model chemical reactivity, including AO efficiency in opaque emulsions. The key to understanding reactivity in organized surfactant media is that reaction mechanisms are consistent with a discrete structures-separate continuous regions duality. Aggregate structures in emulsions are determined by highly cooperative but weak organizing forces that allow reactants to diffuse at rates approaching their diffusion-controlled limit. Reactant distributions for slow thermal bimolecular reactions are in dynamic equilibrium, and their distributions are proportional to their relative solubilities in the oil, interfacial, and aqueous regions. Our chemical kinetic method is grounded in thermodynamics and combines a pseudophase model with methods for monitoring the reactions of AOs with a hydrophobic arenediazonium ion probe in opaque emulsions. We introduce (a) the logic and basic assumptions of the pseudophase model used to define the distributions of AOs among the oil, interfacial, and aqueous regions in microemulsions and emulsions and (b) the dye derivatization and linear sweep voltammetry methods for monitoring the rates of reaction in opaque emulsions. Our results show that this approach provides a unique, versatile, and robust method for obtaining quantitative estimates of AO partition coefficients or partition constants and distributions and interfacial rate constants in emulsions. The examples provided illustrate the effects of various emulsion properties on AO distributions such as oil hydrophobicity, emulsifier structure and HLB, temperature, droplet size, surfactant charge, and acidity on reactant distributions. Finally, we show that the chemical kinetic method provides a natural explanation for the cut-off effect, a maximum followed by a sharp reduction in AO efficiency with increasing alkyl chain length of a particular AO. We conclude with perspectives and prospects. PMID:25805058

  16. 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.

  17. Stabilization mechanism of oil-in-water emulsions by β-lactoglobulin and gum arabic.

    PubMed

    Bouyer, Eléonore; Mekhloufi, Ghozlene; Le Potier, Isabelle; de Kerdaniel, Typhaine du Fou; Grossiord, Jean-Louis; Rosilio, Véronique; Agnely, Florence

    2011-02-15

    Natural biopolymer stabilized oil-in-water emulsions were formulated using β-lactoglobulin (β-lg), gum arabic (GA), and β-lg:GA solutions as an alternative to synthetic surfactants. Emulsions using these biopolymers and their complexes were formulated varying the biopolymer total concentration, the protein-to-polysaccharide ratio, and the emulsification protocol. This work showed that whereas β-lg enabled the formulation of emulsions at concentration as low as 0.5 (w/w)%, GA allowed to obtain emulsions at concentrations equal to or higher than 2.5 (w/w)%. In order to improve emulsion stability, β-lg and GA were complexed through strong attractive electrostatic interactions. GA solution had to be added to previously prepared β-lg emulsions in order to obtain stable emulsions. Interfacial tension and interfacial rheological measurements allowed a better understanding of the possible stabilizing mechanism. β-lg and GA both induced a very effective decrease in interfacial tension and showed interfacial elastic behaviour. In the mixed system, β-lg adsorbed at the interface and GA electrostatically bound to it, leading to the formation of a bi-layer stabilized emulsion. However, emulsion stability was not improved compared to β-lg stabilized emulsion, probably due to depletion or bridging flocculation. PMID:21145063

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

    SciTech Connect

    Somasundaran, Prof. P.

    2001-04-04

    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.

  19. Surfactant compositions

    SciTech Connect

    Novakovic, M.; Abend, P.G.

    1987-09-29

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

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

    SciTech Connect

    Supakanapitak, Sunisa; Boonamnuayvitaya, Virote; Jarudilokkul, Somnuk

    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.

  1. Membrane aging and related phenomena in liquid surfactant membranes process

    SciTech Connect

    Abou-Nemeh, I.; Van Peteghem, A.P. )

    1994-03-01

    The membrane aging phenomenon and its influences on the kinetics of cobalt(II) permeation by the liquid surfactant membranes (LSM) process has been studied. The experimental results showed that the emulsion formulated from the internal aqueous phase and the membrane (organic phase) of a certain age has far-reaching consequences on the kinetics of metal extraction and emulsion stability. The investigations have revealed that there exists an optimal age and composition of the membrane in which the highest extraction (synergism) and the lowest emulsion swelling are achieved. Analytical and instrumental examinations of the membrane phase during aging have shown various chemical and physical changes as a result of the surfactant decomposition, reaction products precipitation and self-association, and macroemulsion formation. 29 refs., 6 figs., 1 tab.

  2. Interactions between polymers and surfactants

    SciTech Connect

    de Gennes, P.G. )

    1990-11-01

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

  3. 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)

  4. Adsorption behavior of direct red 80 and congo red onto activated carbon/surfactant: Process optimization, kinetics and equilibrium

    NASA Astrophysics Data System (ADS)

    Cheng, Zhengjun; Zhang, Lei; Guo, Xiao; Jiang, Xiaohui; Li, Tian

    2015-02-01

    Adsorptions of congo red and direct red 80 onto activated carbon/surfactant from aqueous solution were optimized. The Box-Behnken design (BBD) has been employed to analyze the effects of concentration of surfactant, temperature, pH, and initial concentration of the dye in the adsorption capacity. Their corresponding experimental data could be evaluated excellently by second order polynomial regression models and the two models were also examined based on the analysis of variance and t test statistics, respectively. The optimum conditions were obtained as follows: Cs = 34.10 μM, T = 50 °C, pH = 3.5, and CCR = 160 mg/L for the congo red system, and Cs = 34.10 μM, T = 50 °C, pH = 6.1, and CDR80 = 110 mg/L for the direct red 80 system. And in these conditions, the measured experimental maximum adsorption capacities for the congo red and direct red 80 removals were 769.48 mg/g and 519.90 mg/g, which were consistent with their corresponding predicted values, with small relative errors of -2.81% and -0.67%, respectively. The adsorption equilibrium and kinetics for the two dye adsorptions onto AC/DDAC were also investigated. The experimental data were fitted by four isotherm models, and Langmuir model presented the best fit. The kinetic studies indicated that the kinetic data followed the pseudo-second-order model.

  5. Adsorption behavior of direct red 80 and congo red onto activated carbon/surfactant: process optimization, kinetics and equilibrium.

    PubMed

    Cheng, Zhengjun; Zhang, Lei; Guo, Xiao; Jiang, Xiaohui; Li, Tian

    2015-02-25

    Adsorptions of congo red and direct red 80 onto activated carbon/surfactant from aqueous solution were optimized. The Box-Behnken design (BBD) has been employed to analyze the effects of concentration of surfactant, temperature, pH, and initial concentration of the dye in the adsorption capacity. Their corresponding experimental data could be evaluated excellently by second order polynomial regression models and the two models were also examined based on the analysis of variance and t test statistics, respectively. The optimum conditions were obtained as follows: Cs=34.10 μM, T=50°C, pH=3.5, and CCR=160 mg/L for the congo red system, and Cs=34.10 μM, T=50°C, pH=6.1, and CDR80=110 mg/L for the direct red 80 system. And in these conditions, the measured experimental maximum adsorption capacities for the congo red and direct red 80 removals were 769.48 mg/g and 519.90 mg/g, which were consistent with their corresponding predicted values, with small relative errors of -2.81% and -0.67%, respectively. The adsorption equilibrium and kinetics for the two dye adsorptions onto AC/DDAC were also investigated. The experimental data were fitted by four isotherm models, and Langmuir model presented the best fit. The kinetic studies indicated that the kinetic data followed the pseudo-second-order model. PMID:25305604

  6. Modulating self-assembly behavior of a salt-free peptide amphiphile (PA) and zwitterionic surfactant mixed system.

    PubMed

    Zhang, Han; Sun, Jichao; Xin, Xia; Xu, Wenlong; Shen, Jinglin; Song, Zhaohua; Yuan, Shiling

    2016-04-01

    A salt-free surfactant system formed by a peptide amphiphile with short headgroup (PA,C16-GK-3) and a zwitterionic surfactant (dodecyldimethylamine oxide, C12DMAO) in water has been systematically investigated. The microstructures and properties of C16-GK-3/C12DMAO mixed system were characterized using a combination of microscopic, scattering and spectroscopic techniques, including transmission electron microscopy (TEM), field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Fourier transform infrared (FT-IR), circular dichroism (CD) and rheological measurements. Rich phase transitions have been observed by adjusting the concentration of C16-GK-3. Investigation of the hydrogels of C16-GK-3/C12DMAO with TEM, SEM and AFM showed that all of these hydrogels form nanobelts. The nanobelt formation is performed in a hierarchical manner: β-sheet peptides and C12DMAO first interact each other to form small aggregates, which then arrange themselves to form one dimensional (1D) left-handed ribbons. The ribbons further aggregated into flat and rigid nanobelts. We proposed a mechanism to interpret the self-assembly process according to the specific peptide structure as well as multiple equilibria between the hydrogen bonding interactions between the headgroups of C16-GK-3, between C12DMAO molecules and the headgroups of C16-GK-3, chirality of the amino acid residues and hydrophobic interactions of the alkyl chains. PMID:26773608

  7. The development of self-emulsifying oil-in-water emulsion adjuvant and an evaluation of the impact of droplet size on performance.

    PubMed

    Shah, Ruchi R; Dodd, Stephanie; Schaefer, Mary; Ugozzoli, Mildred; Singh, Manmohan; Otten, Gillis R; Amiji, Mansoor M; O'Hagan, Derek T; Brito, Luis A

    2015-04-01

    Microfluidization is an established technique for preparing emulsion adjuvant formulations for use in vaccines. Although this technique reproducibly yields high-quality stable emulsions, it is complex, expensive, and requires proprietary equipment. For this study, we developed a novel and simple low shear process to prepare stable reproducible emulsions without the use of any proprietary equipment. We found this process can produce a wide range of differently sized emulsions based on the modification of ratios of oil and surfactants. Using this process, we prepared a novel 20-nm-sized emulsion that was stable, reproducible, and showed adjuvant effects. During evaluation of this emulsion, we studied a range of emulsions with the same composition all sized below 200; 20, 90, and 160 nm in vivo and established a correlation between adjuvant size and immune responses. Our studies indicate that 160-nm-sized emulsions generate the strongest immune responses. PMID:25600347

  8. 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

  9. Synthetic Polymers at Interfaces: Monodisperse Emulsions Multiple Emulsions and Liquid Marbles

    NASA Astrophysics Data System (ADS)

    Sun, Guanqing

    The adsorption of polymeric materials at interfaces is an energetically favorable process which is investigated in much diversified fields, such as emulsions, bubbles, foams, liquid marbles. Pickering emulsion, which is emulsion stabilized by solid particles has been investigated for over one century and preparation of Pickering emulsion with narrow size distribution is crucial for both the theoretical study of the stabilization mechanism and practical application, such as templated fabrication of colloidosomes. The precise control over the size and functionality of polymer latices allows the preparation of monodisperse Pickering emulsions with desired sizes through SPG membrane emulsification at rather rapid rate compared to microfludic production. Double or multiple emulsions have long been investigated but its rapid destabilization has always been a major obstacle in applying them into practical applications. The modern living polymerization techniques allow us to prepare polymers with designed structure of block copolymers which makes it possible to prepare ultra-stable multiple emulsions. The precise tuning of the ratio of hydrophobic part over the hydrophilic can unveil the stabilization mechanism. Liquid marble is a new type of materials of which liquid droplets are coated by dry particles. The coating of an outer layer of dry particles renders the liquid droplets non-sticky at solid surface which is useful in transportation of small amount of liquid without leakage at extreme low friction force. The property of liquid marbles relies largely on the stabilizers and the drying condition of polymeric latices is shown to have great influence on the property of liquid marbles. Firstly, an introduction to the interfacial and colloidal science with special attention to topics on emulsions, multiple emulsion and liquid marbles is given in Chapter 1. The unique features of an interface and a discussion on the definition of colloids are introduced prior to the discussion of emulsion stabilization and preparation. A historical review of multiple emulsions is presented subsequently and the stability mechanism is discussed in details with regard to the transportation kinetics of small molecules through the separating membrane of double emulsions. The principle, property and applications of liquid marbles are then summarized. Secondly, the preparation of monodisperse Pickering emulsions stabilized by soft PNIPAM-co-MAA microgels through SPG membrane emulsification is described. The influence of the membrane pore size, pH of the particle dispersion, particle size and the operating parameters of the membrane emulsification device on the size of the emulsion droplets was investigated systematically. The improvement in monodispersity of the emulsion droplets allows us to measure the release profiles of a small molecular dye and a larger nanoparticle through the colloidosomes. It is further demonstrated that the preparation of monodisperse emulsions stabilized by other types of soft particles allows us control the stability of the emulsion with a pH trigger and improved biocompatibility. Thirdly, the preparation of multiple emulsions stabilized by a special designed PEG-b-PS diblock copolymer with desired hydrophobicity by one-step method was presented. The ultra-stability of the as-obtained multiple emulsions was ascribed to the effective steric stabilization of the two interfaces with different polymer configurations at the interfaces. A series of diblock copolymer with increasing PS chain length was then synthesized to investigate the influence of asymmetry ratio on the type of emulsions prepared. It is found that the diblock copolymers with the asymmetry ratio of approximately 1 had the highest power to stabilize multiple emulsions. The multiple emulsions were demonstrated to be a promising platform for controlled release. In the end, particle-stabilized water-in-air liquid marbles were investigated. PSco-MAA nanoparticles synthesized from surfactant-free emulsion polymerization were proved to be effective liquid marble stabilizers. The influence of drying conditions on the properties of liquid marbles was investigated through a macroscopic way. The pH value of the particle dispersion, which influences the protonation states of the particles before freeze-drying, has a profound influence on the property of the stabilized liquid marbles. A brief comment to the future of work of these investigated systems is delivered in the last part.

  10. Reduction of oxygen from electrolyte emulsions with high oxygen contents

    NASA Astrophysics Data System (ADS)

    Kronberger, H.; Bruckner, K.; Fabjan, Ch

    The kinetics of oxygen reduction from electrolyte emulsions containing oxygen carriers was studied with respect to fuel cell applications. Electrochemical experiments including stationary and nonstationary measurements under defined hydrodynamic conditions at a rotating platinum disk electrode revealed that diffusion-controlled limiting currents can be increased significantly at high oxygen concentrations. Additionally, the limiting currents show a strong correlation with the composition and the structure of the emulsions. In particular, the average droplet size of the organic phase and its distribution depends on the nature of the emulsifying agents used for stabilisation. The complex hydrodynamic behaviour of two-phase electrolyte emulsions and the influence of different surfactants seem to outweigh the effect of the total oxygen concentration on the transport kinetics of oxygen.

  11. The effect of different surfactants/plastisizers on the electrical behavior of CNT nano-modified cement mortars

    NASA Astrophysics Data System (ADS)

    Dalla, P. T.; Alafogianni, P.; Tragazikis, I. K.; Exarchos, D. A.; Dassios, K.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    Cement-based materials have in general low electrical conductivity. Electrical conductivity is the measure of the ability of the material to resist the passage of electrical current. The addition of a conductive admixture such as Multi-Walled Carbon Nanotubes (MWCNTs) in a cement-based material increases the conductivity of the structure. This research aims to characterize nano-modified cement mortars with MWCNT reinforcements. Such nano-composites would possess smartness and multi-functionality. Multifunctional properties include electrical, thermal and piezo-electric characteristics. One of these properties, the electrical conductivity, was measured using a custom made apparatus that allows application of known D.C. voltage on the nano-composite. In this study, the influence of different surfactants/plasticizers on CNT nano-modified cement mortar specimens with various concentrations of CNTs (0.2% wt. cement CNTs - 0.8% wt. cement CNTs) on the electrical conductivity is assessed.

  12. 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

  13. Water-oil Janus emulsions: microfluidic synthesis and morphology design.

    PubMed

    Ge, Xue-Hui; Huang, Jin-Pei; Xu, Jian-Hong; Chen, Jian; Luo, Guang-Sheng

    2016-04-14

    In this work we developed a facile method to prepare water-oil Janus emulsions in situ with tunable morphologies by using a double-bore capillary microfluidic device. In addition, by combining the theory model and our liquids' properties, we propose a method to design the morphology of water-oil Janus emulsions. To systematically research Janus morphologies we combined the theory model and the fluids' properties. Under the model guidance, we carefully selected the liquids system where only the interfacial tension between the water phase and the continuous phase changed while keeping the other two interfacial tensions unchanged. Thus we could adjust the Janus morphology by changing the surfactant mass fraction in the continuous phase. In addition, with the double-bore capillary, we prepared water-oil Janus emulsions with a large flow ratio range. By adjusting the flow ratio and the surfactant mass fraction, we successfully prepared Janus emulsions with gradual morphology changes, which would be meaningful in fields that have a high demand for morphology designing of amphiphilic Janus particles. PMID:26947622

  14. 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

  15. Influence of formulation on the oxidative stability of water-in-oil emulsions.

    PubMed

    Dridi, Wafa; Essafi, Wafa; Gargouri, Mohamed; Leal-Calderon, Fernando; Cansell, Maud

    2016-07-01

    The oxidation of water-in-oil (W/O) emulsions was investigated, emphasizing the impact of compositional parameters. The emulsions had approximately the same average droplet size and did not show any physical destabilization throughout the study. In the absence of pro-oxidant ions in the aqueous phase, lipid oxidation of the W/O emulsions was moderate at 60°C and was in the same range as that measured for the neat oils. Oxidation was significantly promoted by iron encapsulation in the aqueous phase, even at 25°C. However, iron chelation reduced the oxidation rate. Emulsions based on triglycerides rich in polyunsaturated fatty acids were more prone to oxidation, whether the aqueous phase encapsulated iron or not. The emulsions were stabilized by high- and low-molecular weight surfactants. Increased relative fractions of high molecular weight components reduced the oxidation rate when iron was present. PMID:26920286

  16. Effects of Operational Conditions on Preparation of Oil in Water Emulsion using Ultrasound

    NASA Astrophysics Data System (ADS)

    Kobayashi, Daisuke; Hiwatashi, Ryosuke; Asakura, Yoshiyuki; Matsumoto, Hideyuki; Shimada, Yuichiro; Otake, Katsuto; Shono, Atsushi

    Ultrasonic emulsification is known to be useful in preparation of nanoemulsions, because use of surfactant can be reduced. Moreover, nanoemulsions with droplet diameters of around 100 nm can be prepared by sequential ultrasonic irradiation from low to high frequency. In this study, oil-in-water systems of toluene-water emulsions were prepared by ultrasonic emulsification and mechanical emulsification. Ultrasound emulsification was found to be more suitable than mechanical emulsification with a homogenizer. In addition, a two-step emulsification method was applied to preparation of emulsion. Crude emulsion was prepared mechanically in the first stage, and this was irradiated with ultrasound in the second stage. The droplet size of the emulsion was found to be influenced by the relationship between droplet size of the crude emulsion and ultrasonic frequency in the second stage.

  17. Development and rheological properties of ecological emulsions formulated with a biosolvent and two microbial polysaccharides.

    PubMed

    Trujillo-Cayado, L A; Alfaro, M C; Muñoz, J; Raymundo, A; Sousa, I

    2016-05-01

    The influence of gum concentration and rhamsan/welan gum ratio on rheological properties, droplet size distribution and physical stability of eco-friendly O/W emulsions stabilized by an ecological surfactant were studied in the present work. The emulsions were prepared with 30wt% α-pinene, a terpenic solvent and an ecological alternative for current volatile organic compounds. Rheological properties of emulsions showed an important dependence on the two studied variables. Flow curves were fitted to the Cross model and no synergistic effect between rhamsan and welan gums was demonstrated. Emulsions with submicron mean diameters were obtained regardless of the gum concentration or the rhamsan/welan ratio used. Multiple light scattering illustrated that creaming was practically eliminated by the incorporation of polysaccharides. The use of rhamsan and welan gums as stabilizers lead to apparent enhancements in emulsion rheology and physical stability. PMID:26826979

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

    PubMed

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

    2012-05-15

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

  19. 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

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

    PubMed

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

    2006-11-15

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

  1. Surface shear inviscidity of soluble surfactants

    PubMed Central

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

    2014-01-01

    Foam and emulsion stability has long been believed to correlate with the surface shear viscosity of the surfactant used to stabilize them. Many subtleties arise in interpreting surface shear viscosity measurements, however, and correlations do not necessarily indicate causation. Using a sensitive technique designed to excite purely surface shear deformations, we make the most sensitive and precise measurements to date of the surface shear viscosity of a variety of soluble surfactants, focusing on SDS in particular. Our measurements reveal the surface shear viscosity of SDS to be below the sensitivity limit of our technique, giving an upper bound of order 0.01 μN·s/m. This conflicts directly with almost all previous studies, which reported values up to 103–104 times higher. Multiple control and complementary measurements confirm this result, including direct visualization of monolayer deformation, for SDS and a wide variety of soluble polymeric, ionic, and nonionic surfactants of high- and low-foaming character. No soluble, small-molecule surfactant was found to have a measurable surface shear viscosity, which seriously undermines most support for any correlation between foam stability and surface shear rheology of soluble surfactants. PMID:24563383

  2. Designing excipient emulsions to increase nutraceutical bioavailability: emulsifier type influences curcumin stability and bioaccessibility by altering gastrointestinal fate.

    PubMed

    Zou, Liqiang; Liu, Wei; Liu, Chengmei; Xiao, Hang; McClements, David Julian

    2015-08-01

    The influence of emulsifier type on the ability of excipient emulsions to improve the solubility, stability, and bioaccessibility of powdered curcumin was examined. Oil-in-water emulsions prepared using three different emulsifiers (whey protein isolate, caseinate, or Tween 80) were mixed with curcumin powder and then incubated at either 30 °C (to simulate applications of salad dressings) or 100 °C (to simulate applications of cooking sauces). The transfer of curcumin into the excipient emulsions was appreciably higher for excipient emulsions held at 100 °C than those held at 30 °C, and was appreciably higher for surfactant-stabilized emulsions than protein-stabilized emulsions. For example, the amounts of curcumin transferred into emulsions held at 30 and 100 °C were 66 and 280 μg mL(-1) for Tween 80, but only 17 and 208 μg mL(-1) for caseinate. The total curcumin concentration in the digesta and mixed micelle phases collected after excipient emulsions were exposed to a simulated gastrointestinal tract (mouth, stomach, and small intestine) depended on emulsifier type. The total amount of curcumin within the digesta was higher for protein-stabilized emulsions than surfactant-stabilized ones, which was attributed to the ability of the proteins to protect curcumin from chemical degradation. For example, the digesta contained 204 μg mL(-1) curcumin for caseinate emulsions, but only 111 μg mL(-1) for Tween 80 emulsions. This study shows the potential of designing excipient emulsions to increase the oral bioavailability of curcumin for food and pharmaceutical applications. PMID:26165514

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

    PubMed

    Ghosh, S; Rousseau, D

    2009-11-01

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

  4. Properties and oxidative stability of emulsions prepared with myofibrillar protein and lard diacylglycerols.

    PubMed

    Diao, Xiaoqin; Guan, Haining; Zhao, Xinxin; Chen, Qian; Kong, Baohua

    2016-05-01

    The objective of this study was to investigate the emulsifying properties and oxidative stability of emulsions prepared with porcine myofibrillar proteins (MPs) and different lipids, including lard, glycerolized lard (GL) and purified glycerolized lard (PGL). The GL and PGL emulsions had significantly higher emulsifying activity indices and emulsion stability indices than the lard emulsion (P<0.05). The PGL emulsion presented smaller droplet sizes, thus decreasing particle aggregation and improving emulsion stability. The static and dynamic rheological observations of the emulsions showed that the emulsions had pseudo-plastic behavior, and the PGL emulsion presented a larger viscosity and a higher storage modulus (G') and loss modulus (G'') compared with the other two emulsions (P<0.05). The formation of thiobarbituric acid-reactive substances, carbonyl contents and total sulfhydryl contents was not significantly different between the emulsions with PGL, GL and lard (P<0.05). In general, lard diacylglycerols enhanced emulsifying abilities and had no adverse effects on the oxidation stability of the emulsions prepared with MPs. PMID:26775153

  5. 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.

  6. 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.

  7. Magnetofluid emulsion: New magnetocontrolled media

    NASA Astrophysics Data System (ADS)

    Bashtovoi, Victor G.; Yarmolchik, Yuri P.

    1994-03-01

    This study has shown that flow dynamics of emulsion consisting of magnetic and nonmagnetic fluids depends on applied magnetic field. So these emulsions may be considered as a magnetic field controlled medium, and in particular as a magnetic field controlled heat carrier. The new dates on rheological properties of these emulsions in the presence of magnetic field are described.

  8. Viscoelastic properties of sterically stabilised emulsions and their stability.

    PubMed

    Tadros, Tharwat

    2015-08-01

    The interaction forces between emulsion droplets containing adsorbed polymeric surfactants and the theory of steric stabilisation are briefly described. The results for the viscoelastic properties of O/W emulsions that are stabilised with partially hydrolysed poly(vinyl acetate) that is commonly referred to as poly(vinyl alcohol) (PVA) with 4% vinyl acetate are given. The effect of the oil volume fraction, addition of electrolytes and increasing temperature is described. This allows one to obtain various parameters such as the adsorbed layer thickness, the critical flocculation concentration of electrolyte (CFC) and critical flocculation temperature (CFT) at constant electrolyte concentration. The viscoelastic properties of O/W emulsions stabilised with an A-B-A block copolymer of polyethylene oxide (A) and polypropylene oxide (B) are described. These emulsions behave as viscoelastic liquids showing a cross-over-point between G' (the elastic component of the complex modulus) and G″ (the viscous component of the complex modulus) at a characteristic frequency. Plots of G' and G″ versus oil volume fraction ϕ show the transition from predominantly viscous to predominantly elastic response at a critical volume fraction ϕ(c). The latter can be used to estimate the adsorbed layer thickness of the polymeric surfactants. Results are also shown for W/O emulsions stabilised with an A-B-A block copolymer of polyhydroxystearic acid (PHS, A) and polyethylene oxide (PEO, B). The viscosity volume fraction curves could be fitted to the Dougherty-Krieger equation for hard-spheres. The results could be applied to give an estimate of the adsorbed layer thickness Δ which shows a decrease with increase of the water volume fraction. This is due to the interpenetration and/or compression of the PHS layers on close approach of the water droplets on increasing the water volume fraction. The last section of the review gives an example of O/W emulsion stability using an AB(n) graft copolymer of polyfructose (A) to which several C12 alkyl chains are grafted. The emulsions are stable both at high temperature and in the presence of high electrolyte concentrations (2 mol dm(-3) NaCl). This high stability is due to the strong adsorption ("anchoring") of the graft copolymer with several C12 alkyl chains and the strong hydration of the polyfructose chains both in water and in the presence of high electrolyte concentrations and temperature. Evidence for this high stability is obtained using disjoining pressure measurements which show a highly stable film between the emulsion droplets and absence of its rupture up to high pressures. PMID:25900262

  9. Preparation and evaluation of tributyrin emulsion as a potent anti-cancer agent against melanoma.

    PubMed

    Kang, Sung Nam; Lee, Eunmyong; Lee, Mi-Kyung; Lim, Soo-Jeong

    2011-02-01

    Histone deacetylase inhibitors such as butyrate are known to exhibit anti-cancer activities in a wide range of cancer including melanoma. In spite of these potencies, butyrate is not practically used for cancer treatment due to its rapid metabolism and very short plasma half-life. Tributyrin, a triglyceride analog of butyrate, can act as a pro-drug of butyrate after being cleaved by intracellular enzymes. The present study sought to investigate a possibility to develop tributyrin emulsion as a potent anti-cancer agent against melanoma. Mixture of Tween80 and 1, 2-dimyristoyl-sn-glycero-3-phosphocholine as a surfactant to disperse tributyrin produced homogeneous emulsions with nanometer sizes, even without a harsh homogenization procedure. Tributyrin emulsion was more potent than butyrate in inhibiting the growth of B16-F10 melanoma cells. Accumulation of cells at sub G(0)/G(1) phase and the DNA fragmentation induced by tributyrin emulsion treatment revealed that tributyrin emulsion inhibited the growth of B16-F10 cells by inducing apoptosis. Treatment with tributyrin emulsion suppressed the colony formation of melanoma cells in a dose-dependent manner. Furthermore, after intraperitoneal administration into mice, tributyrin emulsion inhibited the formation of tumor colonies in the lung following intravenous injection of melanoma cells. Taken together, our data suggests that tributyrin emulsion may be developed as a potent anti-cancer agent against melanoma. PMID:20946006

  10. 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.

  11. 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. . 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.

  12. Formulation and optimization by experimental design of eco-friendly emulsions based on d-limonene.

    PubMed

    Pérez-Mosqueda, Luis M; Trujillo-Cayado, Luis A; Carrillo, Francisco; Ramírez, Pablo; Muñoz, José

    2015-04-01

    d-Limonene is a natural occurring solvent that can replace more pollutant chemicals in agrochemical formulations. In the present work, a comprehensive study of the influence of dispersed phase mass fraction, ϕ, and of the surfactant/oil ratio, R, on the emulsion stability and droplet size distribution of d-limonene-in-water emulsions stabilized by a non-ionic triblock copolymer surfactant has been carried out. An experimental full factorial design 3(2) was conducted in order to optimize the emulsion formulation. The independent variables, ϕ and R were studied in the range 10-50 wt% and 0.02-0.1, respectively. The emulsions studied were mainly destabilized by both creaming and Ostwald ripening. Therefore, initial droplet size and an overall destabilization parameter, the so-called turbiscan stability index, were used as dependent variables. The optimal formulation, comprising minimum droplet size and maximum stability was achieved at ϕ=50 wt%; R=0.062. Furthermore, the surface response methodology allowed us to obtain the formulation yielding sub-micron emulsions by using a single step rotor/stator homogenizer process instead of most commonly used two-step emulsification methods. In addition, the optimal formulation was further improved against Ostwald ripening by adding silicone oil to the dispersed phase. The combination of these experimental findings allowed us to gain a deeper insight into the stability of these emulsions, which can be applied to the rational development of new formulations with potential application in agrochemical formulations. PMID:25734966

  13. Highly concentrated emulsions: 1. Average drop size determination by analysis of incoherent polarized steady light transport.

    PubMed

    Paruta-Tuarez, Emilio; Fersadou, Hala; Sadtler, Véronique; Marchal, Philippe; Choplin, Lionel; Baravian, Christophe; Castel, Christophe

    2010-06-01

    The analysis of incoherent polarized steady light transport is reported as a convenient technique for the drop size determination in highly concentrated oil-in-water emulsions. The studied system consists in heptane-in-water emulsions stabilized with a copolymeric surfactant (Synperonic PE®/L64). Hundred grams of parent emulsions, at two volume fractions of dispersed phase (φ=0.958 and 0.937) were prepared using a semi-batch process. Then, they were diluted with the aqueous phase to obtain volume fractions ranging from 0.886 to 0.958. The use of a copolymeric surfactant allows the dilution of the highly concentrated emulsions without any change in the particle size distribution as confirmed by laser diffraction measurements. We found that the polarization technique allows the determination of the film thickness between water drops rather than their sizes. Consequently, we propose a geometrical relationship to determine an average drop size from the film thickness. The sensitivity of this alternative technique to detect changes in average drop size was studied by changing some process and formulation parameters. Drop size determination in highly concentrated emulsions via this method is useful since the measurement protocol neither involves dilution nor induces structural changes in the emulsion. PMID:20227707

  14. Scaling vs simulations in the head-on collision of viscous drops with insoluble surfactants

    NASA Astrophysics Data System (ADS)

    Vannozzi, Carolina

    2015-11-01

    Scaling arguments are presented to show the effect of the surface diffusivity Ds on the head-on collision of two equal-sized viscous drops in a viscous matrix with insoluble surfactants. The scaling arguments are compared to simulations of the experimental system studied by Yoon et al. where the drops are Polybutadiene(PBD) in PDMS, stabilized by block copolymers surfactants. Overall, the scaling could predict the effect of the different parameters on the drainage time (the surface Peclet number, the Marangoni number and the pushing force due to the external flow), but could not predict the experimental or simulated values. We tested our simulations against the scaling argument of, that claimed that emulsions stabilized by small molecule surfactants can be described with the assumption of non-diffusing surfactants. Here, however, following the same arguments, but without using the Stokes-Einstein expression for the surfactant surface mobility employed in Ref. and by simply substituting the parameters for different emulsion systems, we show that Ds can be neglected only for oil in water emulsions, not for water in oil emulsion.

  15. New polymer/surfactant systems for stabilizing troublesome gumbo shale

    SciTech Connect

    Alonso-Debolt, M.A.; Jarrett, M.A.

    1994-12-31

    With increasing environmental regulations on the use of oil-based (or synthetic-based) invert emulsion drilling fluids, options for designing more inhibitive water-based drilling fluids with greater versatility are being explored. The challenge set for water-based drilling fluid technology is to meet the same performance expectations of oil-based drilling fluids, particularly for improving shale stabilization. This paper discusses the development and application of water-based polymeric mud systems that incorporate new chemical classes of surfactants. These new zwitterionic surfactants demonstrate unique synergistic benefits with polymers for improving shale stabilization.

  16. 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

  17. Investigations on the migration behavior of insulin and related synthetic analogues in CZE, MEKC and MEEKC employing different surfactants.

    PubMed

    Haunschmidt, Manuela; Ortner, Karin; Hainz, Katharina; Bradt, Elke; Sternbauer, Lukas; Buchberger, Wolfgang; Klampfl, Christian W

    2010-05-01

    The retention/migration behavior of insulin and five synthetic insulin analogues in CZE, MEKC and MEEKC employing seven different detergents within the latter two techniques has been investigated. Substantial changes in separation selectivity in MEKC could be observed for several insulins when moving from SDS to cholate-based micellar systems. Customized separations could be achieved by using mixtures of SDS and deoxycholate. A similar effect could be observed in MEEKC although the overall quality of MEEKC separations was inferior to those obtained with MEKC. PMID:20358538

  18. Adsorption of Gemini surfactants onto clathrate hydrates.

    PubMed

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

    2013-12-15

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

  19. 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

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

    PubMed

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

    2013-04-11

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

  1. Double Emulsion Templated Celloidosomes

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  2. FINE GRAIN NUCLEAR EMULSION

    DOEpatents

    Oliver, A.J.

    1962-04-24

    A method of preparing nuclear track emulsions having mean grain sizes less than 0.1 microns is described. The method comprises adding silver nitrate to potassium bromide at a rate at which there is always a constant, critical excess of silver ions. For minimum size grains, the silver ion concentration is maintained at the critical level of about pAg 2.0 to 5.0 during prectpitation, pAg being defined as the negative logarithm of the silver ion concentration. It is preferred to eliminate the excess silver at the conclusion of the precipitation steps. The emulsion is processed by methods in all other respects generally similar to the methods of the prior art. (AEC)

  3. Preparation and Thermal Properties of Fatty Alcohol/Surfactant/Oil/Water Nanoemulsions and Their Cosmetic Applications.

    PubMed

    Okamoto, Toru; Tomomasa, Satoshi; Nakajima, Hideo

    2016-01-01

    Physicochemical properties of oil-in-water (O/W) emulsions containing fatty alcohols and surfactants have been investigated with the aim of developing new formulations that are less viscous and more transparent than conventional milky lotions, as well as for providing greater skin-improving effects. O/W-based creams can be converted to low viscosity milky lotions following their emulsification with a homogenizer at temperatures greater than the transition temperatures of their molecular assemblies (α-gel). The stability of the O/W emulsions evaluated in the current study increased as the transition temperatures of the molecular assemblies formed from their fatty alcohol and surfactant constituents increased. A decrease in the emulsion droplet size led to the formation of a new formulation, which was transparent in appearance and showed a very low viscosity. The absence of a molecular assembly (α-gel) formed by the fatty alcohol and surfactant molecules in the aqueous phase allowed for the formation of a stable transparent and low viscosity nanoemulsion. Furthermore, this decrease in droplet size led to an increase in the interfacial area of the emulsion droplets, with almost all of the fatty alcohol and surfactant molecules being adsorbed on the surfaces of the emulsion droplets. This was found to be important for preparing a stable transparent formulation. Notably, this new formulation exhibited high occlusivity, which was equivalent to that of an ordinary cosmetic milky lotion, and consequently provided high skin hydration. The nanoemulsion was destroyed following its application to the skin, which led to the release of the fatty alcohol and surfactant molecules from the surface of the nanoemulsion into the aqueous phase. These results therefore suggest that the fatty alcohol and surfactant molecules organized the molecular assembly (α-gel) and allowed for the reconstruction of the network structure. PMID:26743668

  4. Preparation and in vitro evaluation of Nystatin micro emulsion based gel.

    PubMed

    Maqsood, Iram; Masood, Muhammad Irfan; Bashir, Sajid; Nawaz, Hafiz Muhammad Awais; Anjum, Aftab Ahmad; Shahzadi, Iram; Ahmad, Mahmood; Imran Masood, Imran Masood

    2015-09-01

    Nystatin is a polyene antimycotic obtained from Streptomyces noursei used in the treatment of topical and transdermal fungal infection. Nystatin is nearly insoluble in water (<0.1) and it is amphoteric in nature. The aim of the present study was to design and develop Nystatin micro emulsion based gel for efficient delivery of drug to the skin by water titration method. The Pseudoternary phase diagrams 1:2, 1:1 and 2:1 were constructed by water titration method. Micro emulsion based gel was prepared by using oleic acid, Tween 20, propylene glycol as an oil phase, surfactant and cosurfactant respectively. Cabopol 940 was used as a gelling agent. In vitro evaluation of micro emulsion based gel was done for pH, Viscosity, spreadability and droplet size. Micro emulsion based gel showed greater antifungal activity against Candida albicansas compared to control formulations. In vitro drug release studies were conducted for micro emulsion based gel and control formulation using Franz diffusion cell. Drug penetration through synthetic skin followed Zero order model as the values for R2 higher in case of zero order equation. The optimized micro emulsion based gel was found to be stable and showed no physical changes when exposed to different temperatures for a period of 4 week. The results indicated that the micro emulsion based gel system studied would be a promising tool for enhancing the percutaneous delivery of Nystatin. PMID:26408879

  5. Formation, antioxidant property and oxidative stability of cold pressed rice bran oil emulsion.

    PubMed

    Thanonkaew, Amonrat; Wongyai, Surapote; Decker, Eric A; McClements, David J

    2015-10-01

    Cold pressed rice bran oil (CPRBO) is used in foods, cosmetics, and pharmaceuticals due to its desirable health and functional attributes. The purpose of this work was to study the formation, antioxidant property and oxidative stability of oil-in-water emulsion of CPRBO. The influence of oil (10-40 % CPRBO) and surfactant (1-5 % glyceryl monostearate (GMS)) concentration on the properties of emulsions were studied. The lightness (L*) and yellowness (b*) of CPRBO emulsions decreased as GMS concentration increased, which was attributed to a decrease in droplet size after homogenization. The CPRBO emulsion was stable during storage at room temperature for 30 days. Increasing the oil concentration in the CPRBO emulsions increased their antioxidant activity, which can be attributed to the corresponding increase in phytochemical content. However, GMS concentration had little impact on the antioxidant activity of CPRBO emulsions. The storage of CPRBO emulsion at room temperature showed that lipid oxidation markers gradually increased after 30 days of storage, which was correlated to a decrease in gamma oryzanol content and antioxidant activity. These results have important implications for the utilization of rice bran oil (RBO) as a function ingredient in food, cosmetic, and pharmaceutical products. PMID:26396397

  6. Influence of Steam Injection and Water-in-Oil Emulsions on Diesel Fuel Combustion Performance

    NASA Astrophysics Data System (ADS)

    Sung, Meagan

    Water injection can be an effective strategy for reducing NOx because water's high specific heat allows it to absorb heat and lower system temperatures. Introducing water as an emulsion can potentially be more effective at reducing emissions than steam injection due to physical properties (such as microexplosions) that can improve atomization and increase mixing. Unfortunately, the immiscibility of emulsions makes them difficult to work with so they must be mixed properly. In this effort, a method for adequately mixing surfactant-free emulsions was established and verified using high speed cinematography. As the water to fuel mass ratio (W/F) increased, emulsion atomization tests showed little change in droplet size and spray angle, but a shorter overall breakup point. Dual-wavelength planar laser induced fluorescence (D-PLIF) patternation showed an increase in water near the center of the spray. Steam injection flames saw little change in reaction stability, but emulsion flames experienced significant losses in stability that limited reaction operability at higher W/F. Emulsions were more effective at reducing NOx than steam injection, likely because of liquid water's latent heat of vaporization and the strategic injection of water into the flame core. OH* chemiluminescence showed a decrease in heat release for both methods, though the decrease was greater for emulsions. Both methods saw decreases in flame length for W/F 0.15. Lastly, flame imaging showed a shift towards a redder appearance with the addition or more water, as well as a reduction in flame flares.

  7. Helix aspersa gelatin as an emulsifier and emulsion stabilizer: functional properties and effects on pancreatic lipolysis.

    PubMed

    Zarai, Zied; Balti, Rafik; Sila, Assaâd; Ben Ali, Yassine; Gargouri, Youssef

    2016-01-20

    Emulsions are widely used in food and pharmaceutical applications for the encapsulation, solubilization, entrapment, and controlled delivery of active ingredients. In order to fulfill the increasing demand for clean label excipients, natural polymers could be used to replace the potentially irritative synthetic surfactants used in emulsion formulation. In the present study, we have studied the properties of oil-in-water emulsions prepared with land snail gelatin (LSG) as the sole emulsifying agent, extracted and described for the first time. LSG was evaluated in terms of proximate composition, oil and water holding capacity, emulsifying and foaming properties, color and amino acid composition. Emulsions of trioctanoylglycerol (TC8) and olive oil were made at different gelatin/oil ratios and changes in droplet-size distribution were determined. The superior emulsifying properties of LSG, the susceptibility of gelatin protein emulsions increasing flocculation on storage, and the coalescence of gelatin emulsions following centrifugation were demonstrated. Furthermore, the effect of LSG on the activity of turkey pancreatic lipase (TPL) was evaluated through the pH-stat methodology with TC8 and olive oil emulsions. The LSG affected the TPL activity in a concentration-dependent way. Our results showed that LSG, comparably to gum arabic, increases the pancreatic lipase activity and improves its stability at the oil-water interface. PMID:26487504

  8. 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.

  9. Enzymatically activated emulsions stabilised by interfacial nanofibre networks.

    PubMed

    Moreira, Ins P; Sasselli, Ivan Ramos; Cannon, Daniel A; Hughes, Meghan; Lamprou, Dimitrios A; Tuttle, Tell; Ulijn, Rein V

    2016-03-01

    We report on-demand formation of emulsions stabilised by interfacial nanoscale networks. These are formed through biocatalytic dephosphorylation and self-assembly of Fmoc(9-fluorenylmethoxycarbonyl)dipeptide amphiphiles in aqueous/organic mixtures. This is achieved by using alkaline phosphatase which transforms surfactant-like phosphorylated precursors into self-assembling aromatic peptide amphiphiles (Fmoc-tyrosine-leucine, Fmoc-YL) that form nanofibrous networks. In biphasic organic/aqueous systems, these networks form preferentially at the interface thus providing a means of emulsion stabilisation. We demonstrate on-demand emulsification by enzyme addition, even after storage of the biphasic mixture for several weeks. Experimental (Fluorescence, FTIR spectroscopy, fluorescence microscopy, electron microscopy, atomic force microscopy) and computational techniques (atomistic molecular dynamics) are used to characterise the interfacial self-assembly process. PMID:26905042

  10. Status of surfactants as penetration enhancers in transdermal drug delivery

    PubMed Central

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

    2012-01-01

    Surfactants are found in many existing therapeutic, cosmetic, and agro-chemical preparations. In recent years, surfactants have been employed to enhance the permeation rates of several drugs via transdermal route. The application of transdermal route to a wider range of drugs is limited due to significant barrier to penetration across the skin which is associated with the outermost stratum corneum layer. Surfactants have effects on the permeability characteristics of several biological membranes including skin. They have the potential to solubilize lipids within the stratum corneum. The penetration of the surfactant molecule into the lipid lamellae of the stratum corneum is strongly dependent on the partitioning behavior and solubility of surfactant. Surfactants ranging from hydrophobic agents such as oleic acid to hydrophilic sodium lauryl sulfate have been tested as permeation enhancer to improve drug delivery. This article reviews the status of surfactants as permeation enhancer in transdermal drug delivery of various drugs. PMID:22368393

  11. 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

  12. Rosmarinus officinalis L. extract and some of its active ingredients as potential emulsion stabilizers: a new approach to the formation of multiple (W/O/W) emulsion.

    PubMed

    Cizauskaite, Ugne; Ivanauskas, Liudas; Jakštas, Valdas; Marksiene, Ruta; Jonaitiene, Laimute; Bernatoniene, Jurga

    2016-09-01

    Nowadays, novel topical formulations loaded with natural functional actives are under intense investigations. Therefore, the aim of our study was to evaluate how the rosemary extract and some of its active ingredients [rosmarinic acid (RA), ursolic acid (UA) and oleanolic acid (OA)] affect technological characteristics of multiple emulsion. Formulation has been prepared by adding investigated solutions (10%) in water/oil/water (W/O/W) multiple emulsion consisting of different lipophilic phases: olive oil and liquid paraffin, with 0.5% emulsifying agent (complex of sodium polyacrylate and polysorbate 20) under constant stirring with mechanical stirrer at room temperature. The emulsion parameters were evaluated using centrifugation test, freeze-thaw cycle test, microscopical and texture analyses. Rosemary's triterpenic saponins UA and OA showed the highest emulsion stabilizing properties: they decreased CI from 3.26% to 10.23% (p < 0.05). According to obtained interfacial tension data, the effect of rosemary active ingredients is not surfactant-like. Even though emulsifier itself at low concentration intends to form directly the multiple emulsion, the obtained results indicate that rosemary extract containing active ingredients does not only serve as functional cosmetic agent due to a number of biological activities, but also offer potential advantages as a stabilizer and an enhancer of W/O/W emulsions formation for dermopharmaceutical and cosmetic preparations. PMID:26000558

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

    PubMed

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

    2013-03-15

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

  14. Effect of temperature on the surface phase behavior and micelle formation of a mixed system of nonionic/anionic surfactants.

    PubMed

    Islam, Md Nazrul; Kato, Teiji

    2005-02-01

    The adsorption and micellar behavior of diethylene glycol mono-n-tetradecyl ether (C14E2), sodium 3,6,9,12-tetraoxaoctacosanoate (TOOCNa), and their mixture at a 1:1 molar ratio have been studied by film balance, Brewster angle microscopy (BAM), and surface tensiometry at different temperatures. The monolayers of pure C14E2 and its mixture with TOOCNa show a first-order phase transition with a conspicuous cusp point in their respective adsorption isotherms. This is further confirmed by the observation of bright two-dimensional condensed phase domains visualized by BAM just after the appearance of the phase transition. It is interesting to note here that for C14E2, condensed domains are observed up to 19 degrees C, while in the mixed system, they are observed up to 22 degrees C. To understand why in the mixed system the domains are observed at higher temperatures than for pure C14E2, we have measured the temperature dependency of the equilibrium surface tension at > or = cmc (gammacmc) values of both the pure and the mixed systems. The gammacmc values of pure C14E2 remain almost constant, while those of pure TOOCNa and its mixture with C14E2 decrease appreciably with increasing temperature. It is concluded that higher degree of dehydration of the ethylene oxide (EO) chain reduces the head-group size of TOOCNa, which outweighs the combined effect of the repulsive interactions between the head-groups and the thermal motion of the adsorbed molecules. Furthermore, C14E2 being inserted into the TOOCNa monolayer reduces the electrostatic repulsions between the charged heads, and consequently, the adsorbed monolayers attain closer molecular packing. As a result, the gammacmc values of both pure TOOCNa and its mixture with C14E2 decrease with increasing temperature. This facilitates the formation of condensed domains in the mixed system at higher temperatures, whereas none of the individual members can show any indicative feature of phase transition under the same experimental conditions. PMID:15576092

  15. Formation of oil-in-water emulsions from natural emulsifiers using spontaneous emulsification: sunflower phospholipids.

    PubMed

    Komaiko, Jennifer; Sastrosubroto, Ashtri; McClements, David Julian

    2015-11-18

    This study examined the possibility of producing oil-in-water emulsions using a natural surfactant (sunflower phospholipids) and a low-energy method (spontaneous emulsification). Spontaneous emulsification was carried out by titrating an organic phase (oil and phospholipid) into an aqueous phase with continuous stirring. The influence of phospholipid composition, surfactant-to-oil ratio (SOR), initial phospholipids location, storage time, phospholipid type, and preparation method was tested. The initial droplet size depended on the nature of the phospholipid used, which was attributed to differences in phospholipid composition. Droplet size decreased with increasing SOR and was smallest when the phospholipid was fully dissolved in the organic phase rather than the aqueous phase. The droplets formed using spontaneous emulsification were relatively large (d > 10 μm), and so the emulsions were unstable to gravitational separation. At low SORs (0.1 and 0.5), emulsions produced with phospholipids had a smaller particle diameter than those produced with a synthetic surfactant (Tween 80), but at a higher SOR (1.0), this trend was reversed. High-energy methods (microfluidization and sonication) formed significantly smaller droplets (d < 10 μm) than spontaneous emulsification. The results from this study show that low-energy methods could be utilized with natural surfactants for applications for which fine droplets are not essential. PMID:26528859

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

    PubMed

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

    2013-07-15

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

  17. 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

  18. Anisotropic microparticles created by phase separation of polymer blends confined in monodisperse emulsion drops.

    PubMed

    Min, Nam Gi; Kim, Bomi; Lee, Tae Yong; Kim, Dahin; Lee, Doh C; Kim, Shin-Hyun

    2015-01-27

    Anisotropic microparticles are promising as a new class of colloidal or granular materials due to their advanced functionalities which are difficult to achieve with isotropic particles. However, synthesis of the anisotropic microparticles with a highly controlled size and shape still remains challenging, despite their intense demands. Here, we report a microfluidic approach to create uniform anisotropic microparticles using phase separation of polymer blends confined in emulsion drops. Two different polymers are homogeneously dissolved in organic solvent at low concentration, which is microfluidically emulsified to produce oil-in-water emulsion drops. As the organic solvent diffuses out, small domains are formed in the emulsion drops, which are then merged, forming only two distinct domains. After the drops are fully consolidated, uniform anisotropic microparticles with two compartments are created. The shape of the resulting microparticles is determined by combination of a pair of polymers and type of surfactant. Spherical microparticles with eccentric core and incomplete shell are prepared by consolidation of polystyrene (PS) and poly(lactic acid) (PLA), and microparticles with single crater are formed by consolidation of PS and poly(methyl methacrylate) (PMMA); both emulsions are stabilized with poly(vinyl alcohol) (PVA). With surfactants of triblock copolymer, acorn-shaped Janus microparticles are obtained by consolidating emulsion drops containing PS and PLA. This microfluidic production of anisotropic particles can be further extended to any combination of polymers and colloids to provide a variety of structural and chemical anisotropy. PMID:25549662

  19. Unique crystal morphologies of glycine grown from octanoic acid-in-water emulsions.

    PubMed

    Nicholson, Catherine E; Cooper, Sharon J; Jamieson, Matthew J

    2006-06-21

    We have obtained both porous and dendritic, intricate morphology crystals of beta-glycine by the novel and simple method of emulsion droplet adhesion and encapsulation. By using octanoic acid emulsified with nonionic surfactants, the adhesion of the emulsion droplets can be so strong that, remarkably, crystal growth often proceeds around the droplets, leading to their inclusion within the single crystals. Consequently, porous single crystals can be produced with the pore diameters ( approximately 10-25 mum) corresponding to the emulsion droplet sizes. Highly intricate, dendritic morphologies for glycine were obtained by increasing the surfactant concentration in the emulsions to 50%. In this case, partial droplet encapsulation results in crystal dendrites growing on either side of adsorbed droplets, with the complex morphologies developing due to the high density of dendritic branches that can occur. These intricate morphologies are in stark contrast to the facetted crystals that normally develop at these low supersaturations in the absence of octanoic acid droplets. This study demonstrates that complex architectures can be attained by using simple emulsion systems and tuning the degree of droplet adhesion. PMID:16771468

  20. Droplet Dynamics of a Flowing Emulsion System

    NASA Astrophysics Data System (ADS)

    Cypull, Olivia; Feitosa, Klebert

    The inner workings of glassy systems have long been a topic of interest for soft material scientists. Similarities between the jamming behavior of emulsions and the glass transition of glassy systems have prompted the conjecture that they might share the same underlying mechanism. Here we study a dense oil-in-water emulsion system forced to flow through a narrow microchannel. By matching the index of refraction of the two phases, we image the internal dynamics of the droplets in a confocal microscope. At low velocity speeds, we find that the velocity along the edge of the microchannel was not significantly different than then the average droplet velocity in the bulk suggesting a near plug flow. By contrast the droplets near the edge experienced more movement perpendicular to the flow indicating the fluidization effect of the confining walls.

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

    PubMed

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

    2011-08-01

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

  2. Droplet coalescence and clustering behavior in microsphere-filled polymeric emulsions under shear flow: the key role of asymmetric interfacial affinities.

    PubMed

    Mao, Chaoying; Kong, Miqiu; Yang, Qi; Li, Guangxian; Huang, Yajiang

    2016-02-01

    The flow-induced spatial organization of the droplet phase in ternary polymeric emulsions consisting of two Newtonian fluids, namely polyisobutylene (PIB) and polydimethylsiloxane (PDMS), in the presence of a small amount of solid polystyrene (PS) microspheres are explored by direct flow visualization. The results suggest that the asymmetric affinities of interfacially located PS microspheres to two fluid components lead to diverse flow-induced morphologies in PIB/PDMS blends with different compositions. In 10/90 blends where microspheres are preferentially wetted by the PIB droplets, significantly promoted coalescence of PIB droplets is observed. Increasing the loading of microspheres or changing the shear rate will alter the size and spatial distribution of PIB droplets. In contrast, in the inverse 90/10 blends where microspheres are wetted by the continuous PIB phase, bridging of PDMS droplets is found, leading to the generation of string-like or grape-like clusters. These results indicate that the flow-induced morphology of PIB/PDMS blends in the presence of PS microspheres is not only determined by the experimental conditions such as shear rate but also to a large extent by the asymmetric interfacial affinities of microspheres for fluid components. PMID:26791278

  3. Surfactant and noninvasive ventilation.

    PubMed

    Blennow, Mats; Bohlin, Kajsa

    2015-01-01

    There is mounting evidence that early continuous positive airway pressure (CPAP) from birth is feasible and safe even in very preterm infants. However, many infants will develop respiratory distress syndrome (RDS) and require surfactant treatment. Combining a noninvasive ventilation approach with a strategy for surfactant administration is important to ensure optimal outcome, but questions remain about the optimal timing, mode of delivery and value of predictive tests for surfactant deficiency. Key findings in this review include the following: (1) a noninvasive ventilation strategy with CPAP from birth has a similar outcome to routine intubation in the delivery room; (2) prophylactic surfactant treatment has no advantage over early CPAP with selective surfactant administration; (3) surfactant during CPAP can be safely administered by rapid intubation-extubation (the INSURE method or via tracheal placement of a thin catheter), and (4) predictive tests for surfactant deficiency are being developed and might in future aid in directing surfactant treatment to infants at risk of developing severe RDS. A strategy for surfactant administration should be part of a noninvasive ventilation approach for preterm infants at risk of developing significant RDS. The different methods for surfactant administration during CPAP are reviewed here. PMID:26044100

  4. Phase Transitions in Nanostructured Polyelectrolyte-Surfactant Complexes

    NASA Astrophysics Data System (ADS)

    Leonard, Michael; Strey, Helmut

    2001-03-01

    When a water-soluble polyelectrolyte is combined with an oppositely-charged surfactant solution at a stoichiometric charge ratio, self-assembly into highly-ordered, water-insoluble structures occurs. We have prepared such complexes with poly(sodium acrylate)-co-acrylamide, alginic acid, and chitosan, combined with cationic and anionic surfactants. The phases exhibited by these complexes in aqueous solution are highly sensitive to such factors as osmotic pressure, salt type, ionic strength, and polyelectrolyte charge density. In this study, we have used small angle X-ray scattering to examine osmotic stress-induced structural phase transitions in these complexes under these various environmental conditions. The morphological consequences of combining polyelectrolytes with swollen, emulsion-bound surfactant micelles were also investigated. Results of this work, as well as the potential to use these complexes as nanoporous, biocompatible materials, will be discussed.

  5. Rheology of Sodium Caseinate Stabilized Oil-in-Water Emulsions

    PubMed

    Dickinson; Golding

    1997-07-01

    We report on shear rheological measurements at 30°C of fine oil-in-water emulsions (volume-surface average diameter < 0.5 &mgr;m) prepared at pH 6.8 with sodium caseinate as the sole emulsifier (1-6 wt%) and n -tetradecane as the dispersed phase (10, 35, or 45 vol%). Strong sensitivity of rheological behavior to total protein concentration was indicated by both steady-state viscometry and small-deformation oscillatory experiments. The behavior can be classified into three types, depending on the protein/oil ratio. (1) Emulsions containing insufficient protein for (near-) saturation protein surface coverage develop a time-dependent increase in low-stress apparent viscosity and associated shear-thinning behavior; this can be attributed to bridging flocculation. (2) Emulsions having full protein surface coverage but relatively little excess unadsorbed protein in the continuous phase are stable Newtonian liquids. (3) Emulsions containing a substantial excess of unadsorbed sodium caseinate exhibit considerable pseudoplasticity which can be attributed to depletion flocculation. Taken as a whole, the time-dependent rheological properties for this set of emulsions as a function of protein content and oil volume fraction are largely consistent with our previous results on the creaming stability and the particle gel microstructure for these same emulsion systems. In particular, the reversible flocculation of emulsion samples of high protein content is readily explicable in terms of depletion flocculation of droplets by unadsorbed protein existing in the form of approximately spherical caseinate submicelles. PMID:9241217

  6. Synthesis and surface and antimicrobial properties of novel cationic surfactants.

    PubMed

    Viscardi, G; Quagliotto, P; Barolo, C; Savarino, P; Barni, E; Fisicaro, E

    2000-12-01

    A series of surfactants with tuned polarity were prepared, including a new class of compounds: gluco-pyridinium surfactants. Pure anomers were obtained by chromatographic separation. The conductivity and surface tension of surfactant solutions in water were measured, and provided interesting information regarding their aggregation behavior. Peculiarities were observed in the premicellar range. Tensidic parameters correlated with antimicrobial activity. A few parameters, mainly the hydrophobicity of the headgroup, may play a role in finding more efficient antimicrobial structures. PMID:11101373

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  8. 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.

  9. SURFACTANT - POLYMER INTERACTION FOR IMPROVED OIL RECOVERY

    SciTech Connect

    Unknown

    1998-10-01

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

  10. Analyzing Benzene and Cyclohexane Emulsion Droplet Collisions on Ultramicroelectrodes.

    PubMed

    Li, Yan; Deng, Haiqiang; Dick, Jeffrey E; Bard, Allen J

    2015-11-01

    We report the collisions of single emulsion oil droplets with extremely low dielectric constants (e.g., benzene, ε of 2.27, or cyclohexane, ε of 2.02) as studied via emulsion droplet reactor (EDR) on an ultramicroelectrode (UME). By applying appropriate potentials to the UME, we observed the electrochemical effects of single-collision signals from the bulk electrolysis of single emulsion droplets. Different hydrophobic redox species (ferrocene, decamethyl-ferrocene, or metalloporphyrin) were trapped in a mixed benzene (or cyclohexane) oil-in-water emulsion using an ionic liquid as the supporting electrolyte and emulsifier. The emulsions were prepared using ultrasonic processing. Spike-like responses were observed in each i-t response due to the complete electrolysis of all of the above-mentioned redox species within the droplet. On the basis of these single-particle collision results, the collision frequency, size distribution, i-t decay behavior of the emulsion droplets, and possible mechanisms are analyzed and discussed. This work demonstrated that bulk electrolysis can be achieved in a few seconds in these attoliter reactors, suggesting many applications, such as analysis and electrosynthesis in low dielectric constant solvents, which have a much broader potential window. PMID:26461801

  11. Multi-scale approach for the rheological characteristics of emulsions using molecular dynamics and lattice Boltzmann method

    PubMed Central

    Choi, Se Bin; Yoon, Hong Min; Lee, Joon Sang

    2014-01-01

    An emulsion system was simulated under simple shear rates to analyze its rheological characteristics using a hierarchical multi-scale approach. The molecular dynamics (MD) simulation was used to describe the interface of droplets in an emulsion. The equations derived from the MD simulation relative to interfacial tension, temperature, and surfactant concentration were applied as input parameters within lattice Boltzmann method (LBM) calculations. In the LBM simulation, we calculated the relative viscosity of an emulsion under a simple shear rate along with changes in temperature, shear rate, and surfactant concentration. The equations from the MD simulation showed that the interfacial tension of the droplets tended to decrease with an increase in temperature and surfactant concentration. The relative viscosity from the LBM simulation decreased with an increase in temperature. The shear thinning phenomena explaining the inverse proportion between shear rate and viscosity were observed. An increase in the surfactant concentration caused an increase in the relative viscosity for a decane-in-water emulsion, because the increased deformation caused by the decreased interfacial tension significantly influenced the wall shear stress. PMID:25332732

  12. Electromagnetic scale models using emulsions

    NASA Astrophysics Data System (ADS)

    Smith, Glenn S.; Scott, Waymond R., Jr.

    1989-04-01

    The electrical constitutive parameters of materials in a scale model and the corresponding full-sized system must satisfy certain relationships. Thus, it is desirable to have a series of materials with a range of electrical parameters or mixtures of materials with adjustable electrical parameters for use in scale models. Simple emulsions are examined as materials with adjustable electrical constitutive parameters. These emulsions are mixtures of soil, saline solution, and a suitable stabilizing agency (emulsifier). Since the relative permittivities of oil and water are around two and eighty, respectively, a large range of permittivity can be obtained for the emulsions. The conductivity of the emulsions can be adjusted by changing the normality of the saline solution. A series of oil-in-water emulsions (oil droplets in water), suitable for use in scale models, is developed; this includes the selection of an appropriate emulsifier. The electrical constitutive parameters of these emulsions are adjustable over wide ranges, and are predictable from a simple formula. As an example, an emulsion that is a scale model for red clay earth is described. This emulsion matches the electrical constitutive parameters of the clay, including the dispersion in the conductivity, over a ten-to-one frequency range.

  13. Tunable Pickering emulsions with polymer-grafted lignin nanoparticles (PGLNs).

    PubMed

    Silmore, Kevin S; Gupta, Chetali; Washburn, Newell R

    2016-03-15

    Lignin is an abundant biopolymer that has native interfacial functions but aggregates strongly in aqueous media. Polyacrylamide was grafted onto kraft lignin nanoparticles using reversible addition-fragmentation chain transfer (RAFT) chemistry to form polymer-grafted lignin nanoparticles (PGLNs) that tune aggregation strength while retaining interfacial activities in forming Pickering emulsions. Polymer graft density on the particle surface, ionic strength, and initial water and cyclohexane volume fractions were varied and found to have profound effects on emulsion characteristics, including emulsion volume fraction, droplet size, and particle interfacial concentration that were attributed to changes in lignin aggregation and hydrophobic interactions. In particular, salt concentration was found to have a significant effect on aggregation, zeta potential, and interfacial tension, which was attributed to changes in solubility of both the kraft lignin and the polyacrylamide grafts. Dynamic light scattering, UV-vis spectroscopy, optical microscopy, and tensiometry were used to quantify emulsion properties and nanoparticle behavior. Under all conditions, the emulsions exhibited relatively fast creaming but were stable against coalescence and Ostwald ripening for a period of months. All emulsions were also oil-in-water (o/w) emulsions, as predicted by the Bancroft rule, and no catastrophic phase inversions were observed for any nanoparticle compositions. We conclude that lower grafting density of polyacrylamide on a lignin core resulted in high levels of interfacial activity, as characterized by higher concentration at the water-cyclohexane interface with a corresponding decrease in interfacial tension. These results indicate that the interfacial properties of polymer-grafted lignin nanoparticles are primarily due to the native hydrophobic interactions of the lignin core. These results suggest that the forces that drive aggregation are also correlated with interfacial activities, and polymer-nanoparticle interactions are critical for optimizing interfacial activities. Controlled radical polymerization is a powerful tool for polymer grafting that can leverage the intrinsic interfacial functions of lignin for the formation of Pickering emulsions. PMID:26707776

  14. Effects of residual surfactants on the chemistry of nanostructured barium hexaaluminate type catalysts

    SciTech Connect

    Khan, N.A.; Natesakhawat, S.; Matranga, C.S.; Sanders, T.; Veser, G.

    2007-03-01

    While there is a growing body of literature on nanostructured materials made by reverse microemulsion methods, there is little information on how the surfactants used to create these emulsions affect the final chemical properties of these nanoparticles. For catalytic applications, this residue can block active sites, which can have detrimental effects on reactivity. We have used thermogravimetric analysis, XPS, XRD, and infrared spectroscopy to study the chemistry of residual surfactants in nanostructured barium hexaaluminate-supported platinum catalysts synthesized by reverse microemulsion techniques. These nanocatalysts have excellent CH4 oxidation activity and resist sintering up to 1200 ºC. We find that up to ~50 wt. % of the catalyst is composed of residual surfactant at temperatures below 500 ºC. In-situ infrared studies show that the surfactant significantly alters CO adsorption and oxidation. Several calcination and rinsing procedures were evaluated to determine their efficacy on surfactant removal and to evaluate their effect on reactivity.

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

    PubMed

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

    2015-05-01

    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

  16. Towards unravelling surfactant transport

    NASA Astrophysics Data System (ADS)

    Sellier, Mathieu; Panda, Satyananda

    2015-11-01

    Surfactant transport arises in many natural or industrial settings. Examples include lipid tear layers in the eye, pulmonary surfactant replacement therapy, or industrial coating flows. Flows driven by the surface tension gradient which arises as a consequence of surfactant concentration inhomogeneity, also known as Marangoni-driven flows, have attracted the attention of fluid dynamists for several decades and has led to the development of sophisticated models and the undeniable advancement of the understanding of such flows. Yet, experimental confirmation of these models has been hampered by the difficulty in reliably and accurately measuring the surfactant concentration and its temporal evolution. In this contribution, we propose a methodology which may help shed some light on surfactant transport at the surface of thin liquid films. The surface stress induced by surfactant concentration induces a flow at the free surface which is visible and measurable. In the context of thin film flows for which the lubrication approximation hold, we demonstrate how the knowledge of this free surface flow field provides sufficient information to reconstruct the surfactant tension field. From the surface tension and an assumed equation of state, the local surfactant concentration can also be calculated and other transport parameters such as the surfactant surface diffusivity indirectly inferred. In this contribution, the proposed methodology is tested with synthetic data generated by the forward solution of the governing partial differential equations in order to illustrate the feasibility of the algorithm and highlight numerical challenges.

  17. Surfactants, skin cleansing protagonists.

    PubMed

    Corazza, M; Lauriola, M M; Zappaterra, M; Bianchi, A; Virgili, A

    2010-01-01

    The correct choice of cosmetic products and cleansers is very important to improve skin hydration, to provide moisturizing benefits and to minimize cutaneous damage caused by surfactants. In fact, surfactants may damage protein structures and solubilize lipids. Soaps, defined as the alkali salts of fatty acids, are the oldest surfactants and are quite aggressive. Syndets (synthetic detergents) vary in composition and surfactant types (anionic, cationic, amphotheric, non-ionic). These new skin cleansing products also contain preservatives, fragrances, and sometimes emollients, humectants and skin nutrients. We present a revision of the literature and discuss recent findings regarding skin cleansers. PMID:19614860

  18. Surfactant phospholipid metabolism

    PubMed Central

    Agassandian, Marianna; Mallampalli, Rama K.

    2012-01-01

    Pulmonary surfactant is essential for life and is comprised of a complex lipoprotein-like mixture that lines the inner surface of the lung to prevent alveolar collapse at the end of expiration. The molecular composition of surfactant depends on highly integrated and regulated processes involving its biosynthesis, remodeling, degradation, and intracellular trafficking. Despite its multicomponent composition, the study of surfactant phospholipid metabolism has focused on two predominant components, disaturated phosphatidylcholine that confers surface-tension lowering activities, and phosphatidylglycerol, recently implicated in innate immune defense. Future studies providing a better understanding of the molecular control and physiological relevance of minor surfactant lipid components are needed. PMID:23026158

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

    DOEpatents

    Johnson, Jr., James S.; Westmoreland, Clyde G.

    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.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

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

  2. Preparation of polystyrene latex particles by γ-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- γ-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.

  3. Emulsions of oil from Adenanthera pavonina L. seeds and their protective effect.

    PubMed

    Jaromin, Anna; Zarnowski, Robert; Kozubek, Arkadiusz

    2006-01-01

    In our previous study, we developed very stable formulations of submicron oil-in-water emulsions from Adenanthera pavonina L. (family Leguminosae, subfamily Mimosoideae) seed oil, stabilised with soybean lecithin (SPC). Continuing our research, we introduced an additional co-emulsifier, Tween 80, to those formulations in order to decrease the size of the emulsion particles and improve their stability. Formulations with a mean particle size ranging from 43.6 to 306.5 nm and a negative surface charge from -45.3 to -28.5 mV were obtained. Our stability experiments also revealed that most of the tested formulations had a very good degree of stability over a 3-month storage period, both at 4 degrees C and at room temperature. Since many intravenous injectable drugs exhibit lytic activity against erythrocytes, we examined this activity for the emulsion form of cardol, a natural compound with already proven hemolytic properties. The incorporation of this agent into the emulsion caused an evident decrease in hemolytic activity (97-99%). This highly protective effect, observed against sheep erythrocytes, was independent of both the composition and the particle size of the emulsions used. Our studies suggest that nonionic surfactant/phospholipid-based emulsions containing this edible oil of A. pavonina L. may be useful as an alternative formulation matrix for pharmaceutical, nutritional or cosmetic applications of otherwise membrane-acting components. PMID:16874455

  4. 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

  5. Emulsions of crude glycerin from biodiesel processing with fuel oil for industrial heating.

    PubMed

    Mize, Hannah E; Lucio, Anthony J; Fhaner, Cassie J; Pratama, Fredy S; Robbins, Lanny A; Karpovich, David S

    2013-02-13

    There is considerable interest in using crude glycerin from biodiesel production as a heating fuel. In this work crude glycerin was emulsified into fuel oil to address difficulties with ignition and sustained combustion. Emulsions were prepared with several grades of glycerin and two grades of fuel oil using direct and phase inversion emulsification. Our findings reveal unique surfactant requirements for emulsifying glycerin into oil; these depend on the levels of several contaminants, including water, ash, and components in MONG (matter organic non-glycerin). A higher hydrophile-lipophile balance was required for a stable emulsion of crude glycerin in fuel oil compared to water in fuel oil. The high concentration of salts from biodiesel catalysts generally hindered emulsion stability. Geometric close-packing of micelles was carefully balanced to mechanically stabilize emulsions while also enabling low viscosity for pumping and fuel injection. Phase inversion emulsification produced more stable emulsions than direct emulsification. Emulsions were tested successfully as fuel for a waste oil burner. PMID:23331034

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

    SciTech Connect

    Hu, S.Y.B.; Wiencek, J.M.

    1998-03-01

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

  7. Two-phase structure of polyelectrolyte gel/surfactant complexes

    NASA Astrophysics Data System (ADS)

    Tararyshkin, Denis; Kramarenko, Elena; Khokhlov, Alexei

    2007-04-01

    The behavior of lightly cross-linked polyelectrolyte hydrogel swelling in the solution of oppositely charged surfactants is studied theoretically. It is shown that if there is a lack of surfactant in the solution intragel separation into two phases differing in swelling ratios and surfactant content can take place. The surfactant ions concentrate and form micelles in a part of the gel and this part collapses while the rest of the gel remains swollen. The two-phase region widens with an increase of ionization degree of the gel subchains.

  8. LNAPL Removal from Unsaturated Porous Media using Surfactant Infiltration

    SciTech Connect

    Zhong, Lirong; Oostrom, Martinus

    2012-11-19

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

  9. 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

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed

    Sabouni, R; Gomaa, H G

    2015-06-14

    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

  12. Estimation hydrophilic-lipophilic balance number of surfactants

    NASA Astrophysics Data System (ADS)

    Pawignya, Harsa; Prasetyaningrum, Aji; Dyartanti, Endah R.; Kusworo, Tutuk D.; Pramudono, Bambang

    2016-02-01

    Any type of surfactant has a hydrophilic-lipophilic balance number (HLB number) of different. There are several methods for determining the HLB number, with ohysical properties of surfactant (solubility cloud point and interfacial tension), CMC methods and by thermodynamics properties (Free energy Gibbs). This paper proposes to determined HLB numbers from interfelation methods. The result of study indicated that the CMC method described by Hair and Moulik espesially for nonionic surfactant. The application of exess Gibbs free energy and by implication activity coefficient provides the ability to predict the behavior of surfactants in multi component mixtures of different concentration. Determination of HLB number by solubility and cloud point parameter is spesific for anionic and nonionic surfactant but this methods not available for cationic surfactants.

  13. 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

  14. 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

  15. Turbulent drag reduction in nonionic surfactant solutions

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  16. 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.

  17. 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...

  18. SURFACTANTS IN LUBRICATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surfactants are one of the most widely applied materials by consumers and industry. The application areas for surfactants span from everyday mundane tasks such as cleaning, to highly complex processes involving the formulation of pharmaceuticals, foods, pesticides, lubricants, etc. Even though sur...

  19. 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 (?Gads) in both mixtures decreased compared with a single surfactant which is attributed to stronger interactions in mixtures.

  20. 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

  1. 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.

  2. Cation selectivity in a toluene emulsion membrane system

    SciTech Connect

    Izatt, R.M.; Dearden, D.V.; Witt, E.R.; McBride, D.W. Jr.; Christensen, J.J.

    1984-01-01

    Metal separations from various mixtures of alkali metal, alkaline earth metal, Cu/sup 2 +/, Zn/sup 2 +/, Ag/sup +/, Tl/sup +/, and Pb/sup 2 +/ nitrates were studied using an emulsion membrane system. The membrane consisted of a water-in-oil emulsion composed of 0.050 M Li/sub 4/P/sub 2/O/sub 7/ in H/sub 2/O and 0.020 M dicyclohexano-18-crown-6 (DC18C6) in toluene with sorbitan monooleate serving as surfactant. The emulsion was placed into an aqueous source phase solution of the metal nitrates of interest. Of the cations studied, Pb/sup 2 +/ was transported most rapidly and selectively. The selectivity of the system for particular cations is governed by the relative M/sup n+/-DC18C6 and M/sup n+/-P/sub 2/O/sub 7//sup 4 -/ complex stabilities. Formation of a sufficiently stable M/sup n+/-DC18C6 complex is necessary to partition cations into the toluene membrane, and formation of a more stable M/sup n+/-P/sub 2/O/sub 7//sup 4 -/ complex is necessary to strip cations from the membrane into the receiving phase. 17 references, 2 figures, 6 tables.

  3. Long-term stability of crystal-stabilized water-in-oil emulsions.

    PubMed

    Ghosh, Supratim; Pradhan, Mamata; Patel, Tejas; Haj-Shafiei, Samira; Rousseau, Dérick

    2015-12-15

    The impact of cooling rate and mixing on the long-term kinetic stability of wax-stabilized water-in-oil emulsions was investigated. Four cooling/mixing protocols were investigated: cooling from 45°C to either 25°C or 4°C with/without stirring and two cooling rates - slow (1°C/min) and fast (5°C/min). The sedimentation behaviour of the emulsions was significantly affected by cooling protocol. Stirring was critical to the stability of all emulsions, with statically-cooled (no stirring) emulsions suffering from extensive aqueous phase separation. Emulsions stirred while cooling showed sedimentation of a waxy emulsion layer leaving a clear oil layer at the top, with a smaller separation and droplet size distribution at 4°C compared to 25°C, indicating the importance of the amount of crystallized wax on emulsion stability. Light microscopy revealed that crystallized wax appeared both on the droplet surface and in the continuous phase, suggesting that stirring ensured dispersibility of the water droplets during cooling as the wax was crystallizing. Wax crystallization on the droplet surface provided stability against droplet coalescence while continuous phase wax crystals minimized inter-droplet collisions. The key novel aspect of this research is in the simplicity to tailor the spatial distribution of wax crystals, i.e., either at the droplet surface or in the continuous phase via use of a surfactant and judicious stirring and/or cooling. Knowledge gained from this research can be applied to develop strategies for long-term storage stability of crystal-stabilized W/O emulsions. PMID:26343977

  4. 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

  5. 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 μm 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

  6. 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

  7. 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.

  8. Bubble motion in aqueous surfactant solutions

    SciTech Connect

    Liao, Y.; McLaughlin, J.B.

    2000-04-15

    This paper presents the results of numerical simulations of the unsteady motion of a single bubble that is released or injected into water. The governing equations are solved with a finite difference method using an adaptive boundary-fitted coordinate system. Results are shown for bubbles in the size range 0.72 to 1.5 mm. The effects of surfactants on the motion and shape of the bubble are investigated. When the surfactant concentration is sufficiently small, the bubble attains a maximum velocity before slowing down to its steady-state velocity. Although the steady-state velocity is nearly independent of surfactant concentration, the maximum velocity can be comparable to steady-state velocity in pure water. This behavior is observed even when the bubble is allowed to equilibrate prior to releasing it. The formation of an immobilized surfactant cap is observed soon after the bubble is released. The effect of the injection velocity on the bubble velocity profile is investigated. The effects of the sorption rate constants and the bulk surfactant concentration on the behavior of the bubble are investigated. The feasibility of using experimental measurements and simulations of unsteady bubble velocities to estimate sorption rate constants is discussed.

  9. Numerical analysis of electromagnetic cascades in emulsion chambers

    NASA Technical Reports Server (NTRS)

    Plyasheshnikov, A. V.; Vorobyev, K. V.

    1985-01-01

    A new calculational scheme of the Monte Carlo method assigned for the investigation of the development of high and extremely high energy electromagnetic cascades (EMC) in the matter was elaborated. The scheme was applied to the analysis of angular and radial distributions of EMC electrons in the atmosphere. By means of this scheme the EMC development in dense medium is investigated and some preliminary data are presented on the behavior of EMC in emulsion chambers. The results of more detailed theoretical analysis of the EMC development in emulsion chambers are discussed.

  10. Formation of pickering emulsions using ion-specific responsive colloids.

    PubMed

    Tan, Khooi Y; Gautrot, Julien E; Huck, Wilhelm T S

    2011-02-15

    The ability to control the dispersion, aggregation, and assembly of colloidal systems is important for a number of applications, for instance, Pickering emulsions, drug and gene delivery, control of fluid rheology, and the formation of colloidal crystal arrays. We generated a responsive colloidal system based on polymer-brush-grafted silica nanoparticles and demonstrated that such a colloidal system can be used to produce stable oil-in-water Pickering emulsions. Cationic poly(2-(methacryloyloxy)-ethyl-trimethyl-ammonium chloride) (PMETAC) brushes were grown from silica nanoparticles (diameter ∼320 nm) through surface-initiated atom-transfer radical polymerization (ATRP). PMETAC brushes are attractive coatings for controlling the behavior of colloidal systems, owing to their ion-specific collapse resulting in the switching of surface hydrophilicity. Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta-potential measurements indicated the successful grafting of PMETAC brushes on nanoparticles. The resulting colloidal dispersion was shown to be responsive to perchlorate ions (ClO(4)(-)), which triggered particle aggregation and enabled the generation of Pickering emulsions. The onset of aggregation depended on the polymer chain length. Aggregation was not affected by the initiator density and brush conformational changes. Further studies suggested that particle aggregation and the formation of stable Pickering emulsions were not simply due to brush collapse but also were due to a gradual shielding of electrostatic repulsion. Finally, the stability and homogeneity of the resulting Pickering emulsions were studied. PMID:20839829

  11. Metal separation using emulsion liquid membranes

    SciTech Connect

    Izatt, R.M.; Dearden, D.V.; McBride, D.W. Jr.; Oscarson, J.L.; Lamb, J.D.; Christensen, J.J.

    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 Li/sub 4/P/sub 2/O/sub 7/ receiving phase were studied with respect to the disappearance of metal from the source phase as a function of time. The salts Pb(NO/sub 3/)/sub 2/, Sr(NO/sub 3/)/sub 2/, TlNO/sub 3/, and LiNO/sub 3/ were studied both singly and in mixtures of Pb(NO/sub 3/)/sub 2/ with each of the other salts. In all mixtures studied, Pb/sup 2 +/ was transported first, followed by the second cation (except Li/sup +/ which was not transported). An excess of a second salt with a common anion enhanced the transport of Pb/sup 2 +/. Modeling of these systems was discussed. Source phases containing basic (pH 11) K(Al(OH)/sub 4/) solutions were studied using the same membrane and a 0.15 M H/sub 3/PO/sub 4/ receiving phase. K/sup +/ and Al(III) (as aluminate anion) were both found to transport in this system, but no transport of Al(III) and little transport of K/sup +/ were detected when DC18C6 was absent.

  12. Metathesis depolymerizable surfactants

    DOEpatents

    Jamison, Gregory M.; Wheeler, David R.; Loy, Douglas A.; Simmons, Blake A.; Long, Timothy M.; McElhanon, James R.; Rahimian, Kamyar; Staiger, Chad L.

    2008-04-15

    A class of surfactant molecules whose structure includes regularly spaced unsaturation in the tail group and thus, can be readily decomposed by ring-closing metathesis, and particularly by the action of a transition metal catalyst, to form small molecule products. These small molecules are designed to have increased volatility and/or enhanced solubility as compared to the original surfactant molecule and are thus easily removed by solvent extraction or vacuum extraction at low temperature. By producing easily removable decomposition products, the surfactant molecules become particularly desirable as template structures for preparing meso- and microstructural materials with tailored properties.

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

    SciTech Connect

    Varghese, B.K.; Cleveland, T.G.

    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.

  14. 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.

  15. 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

  16. Rheological characterization of O/W emulsions incorporated with neutral and charged polysaccharides.

    PubMed

    Vianna-Filho, Ricardo Padilha; Petkowicz, Carmen Lúcia Oliveira; Silveira, Joana Léa Meira

    2013-03-01

    The effects of polysaccharides, including xyloglucan from Hymenaea courbaril (XG), galactomannans from Schizolobium parahybae (GMSP) and Mimosa scabrella (GMMS), xanthan gum (XT), sodium hyaluronate (HNa) and Fucogel(®) (FG), on the rheological behavior of cosmetic emulsions were evaluated. These incorporations gave rise to six emulsified systems, denoted XGE, GMSPE, GMMSE, XTE, HNaE and FGE, respectively. The emulsion consistency was found to follow the trend GMSPE>XGE>HNaE>FGE>XTE>GMMSE. In general, the addition of polysaccharides increased the viscoelastic properties of the emulsions and decreased the creep compliance. The neutral polysaccharides (GMSPE, GMMSE) led to better stability of the emulsions after storing for 20 days relative to charged polymers. It was found that polysaccharides XG, GMSP and GMMS, which come from the seeds of native Brazilian plant species, might be used to modify the flow properties and stabilities of oil-water emulsions. PMID:23465929

  17. An enzyme containing microemulsion based on skin friendly oil and surfactant as decontamination medium for organo phosphates: phase behavior, structure, and enzyme activity.

    PubMed

    Stehle, Ralf; Schulreich, Christoph; Wellert, Stefan; Gäb, Jürgen; Blum, Marc-Michael; Kehe, Kai; Richardt, Andras; Lapp, Alain; Hellweg, Thomas

    2014-01-01

    The present contribution presents a microemulsion system containing cosmetic oil and sugar surfactant and the enzyme diisopropyl fluorophosphatase (DFPase) as active agent for the decontamination of human skin. The bicontinuous structure and the physical properties of the microemulsion are characterized by dynamic light scattering and small angle neutron scattering. The DFPase from the squid Loligo vulgaris is catalyzing the hydrolysis of highly toxic organophosphates. The effect of the enzyme on the structure of the microemulsion is investigated. Moreover, the enzyme/microemulsion system is also studied with respect to its activity using nuclear magnetic resonance spectroscopy leading to promising results. A fast decomposition of the nerve agent sarin is achieved. PMID:24183440

  18. 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.

  19. Phosphine oxide surfactants revisited.

    PubMed

    Stubenrauch, Cosima; Preisig, Natalie; Laughlin, Robert G

    2016-04-01

    This review summarizes everything we currently know about the nonionic surfactants alkyl dimethyl (CnDMPO) and alkyl diethyl (CnDEPO) phosphine oxide (PO surfactants). The review starts with the synthesis and the general properties (Section 2) of these compounds and continues with their interfacial properties (Section 3) such as surface tension, surface rheology, interfacial tension and adsorption at solid surfaces. We discuss studies on thin liquid films and foams stabilized by PO surfactants (Section 4) as well as studies on their self-assembly into lyotropic liquid crystals and microemulsions, respectively (Section 5). We aim at encouraging colleagues from both academia and industry to take on board PO surfactants whenever possible and feasible because of their broad variety of excellent properties. PMID:26869216

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

    PubMed

    Nakamura, Kazuho; Matsumoto, Kanji

    2013-01-01

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

  1. Stabilization of phase inversion temperature nanoemulsions by surfactant displacement.

    PubMed

    Rao, Jiajia; McClements, David Julian

    2010-06-01

    Nanoemulsions are finding increasing utilization in the food and beverage industry to encapsulate and protect lipophilic functional components. Low-intensity methods, such as the phase inversion temperature (PIT) approach, are of particular interest for forming food-grade nanoemulsions because of their ease of formation and relatively low energy costs. Nevertheless, this type of emulsion tends to be highly unstable to droplet coalescence after preparation. In this study, we develop a potential solution to this problem using model water/surfactant (Brij 30, C(12)E(4))/oil (tetradecane) systems. The PIT and system morphology were determined by monitoring the temperature dependence of the electrical conductivity, turbidity, and microstructure of the emulsions. Nanoemulsions were formed by holding water/surfactant/oil mixtures at their PIT and then rapidly cooling them. The influence of storage temperature on emulsion stability was investigated, which indicated that the optimum temperature (13 degrees C) was about 27 degrees C lower than the PIT (approximately 40 degrees C). Higher storage temperatures resulted in an increase in droplet growth rate due to coalescence, while lower temperatures led to gelation. Nanoemulsions that were relatively stable to coalescence could be formed at ambient temperatures by adding either Tween 80 (0.2 wt %) or SDS (0.1 wt %) to displace the Brij 30 from the droplet surfaces. We propose that these surfactants increase nanoemulsion stability by changing the optimum curvature of the interfacial layer, as well as by increasing the repulsive interactions (steric or electrostatic) between the droplets. This study may lead to a novel approach to create stable nanoemulsion-based delivery systems that are suitable for utilization within the food industry. PMID:20476765

  2. Absorption of morphine from a slow-release emulsion used to induce morphine dependence in rats.

    PubMed

    Salem, A; Hope, W

    1998-10-01

    This study was performed to measure absorption of morphine from the injection site following treatment of rats with slow-release emulsions formulated with morphine hydrochloride and morphine base. Samples of emulsion were collected from the injection site of halothane anesthetized animals at 24 and 48 h following emulsion treatment and concentrations of morphine remaining in the emulsion were analyzed using high-performance liquid chromatography (HPLC). In another group of morphine-treated rats, at times equivalent to collecting samples of emulsion, the intensity of naloxone-precipitated withdrawal behaviors was monitored. Both morphine base- and hydrochloride-containing emulsions induced a high degree of physical dependence in animals treated over 48 h. Release of morphine from emulsions containing morphine base was slower than that from the hydrochloride formulations. In the 24-h morphine base-treated animals, approximately 45% was absorbed from the injection site as opposed to 99% in the 24-h morphine hydrochloride-treated animals. These results suggest that morphine base containing emulsions provide a more sustained exposure to the opioid. PMID:10334632

  3. Surfactant effects on SF6 hydrate formation.

    PubMed

    Lee, Bo Ram; Lee, Ju Dong; Lee, Hyun Ju; Ryu, Young Bok; Lee, Man Sig; Kim, Young Seok; Englezos, Peter; Kim, Myung Hyun; Kim, Yang Do

    2009-03-01

    Sulfur hexafluoride (SF(6)) has been widely used in a variety of industrial processes, but it is one of the most potent greenhouse gases. For this reason, it is necessary to separate or collect it from waste gas streams. One separation method is through hydrate crystal formation. In this study, SF(6) hydrate was formed in aqueous surfactant solutions of 0.00, 0.01, 0.05, 0.15 and 0.20 wt% to investigate the effects of surfactants on the hydrate formation rates. Three surfactants, Tween 20 (Tween), sodium dodecyl sulfate (SDS) and linear alkyl benzene sulfonate (LABS), were tested in a semi-batch stirred vessel at the constant temperature and pressures of 276.2 K and 0.78 MPa, respectively. All surfactants showed kinetic promoter behavior for SF(6) hydrate formation. It was also found that SF(6) hydrate formation proceeded in two stages with the second stage being the most rapid. In situ Raman spectroscopy analysis revealed that the increased gas consumption rate with the addition of surfactant was possibly due to the increased gas filling rate in the hydrate cavity. PMID:19058810

  4. 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.

  5. Potential applications of microbial surfactants in biomedical sciences.

    PubMed

    Singh, Pooja; Cameotra, Swaranjit Singh

    2004-03-01

    The main commercial use of biosurfactants is in pollution remediation because of their ability to stabilize emulsions. This enhances the solubility and availability of hydrophobic pollutants, thus increasing their potential for biodegradation. One useful property of many biosurfactants that has not been reviewed extensively is their antimicrobial activity. Several biosurfactants have strong antibacterial, antifungal and antiviral activity. Other medically relevant uses of biosurfactants include their role as anti-adhesive agents to pathogens, making them useful for treating many diseases and as therapeutic and probiotic agents. Here, we discuss some of the new and exciting applications and related developments of various microbial surfactants in the field of biomedical sciences. PMID:15036865

  6. Chitosan-Based Conventional and Pickering Emulsions with Long-Term Stability.

    PubMed

    Wang, Xiao-Yan; Heuzey, Marie-Claude

    2016-02-01

    Chitosan-based conventional and Pickering oil-in-water (O/W) emulsions with very fine droplet size (volume average diameter, dv, as low as 1.7 μm) and long-term stability (up to 5 months) were ultrasonically generated at different pH values without the addition of any surfactant or cross-linking agent. The ultrasonication treatment was found to break and disperse chitosan agglomerates effectively (particularly at pH ≥ 4.5) and also reduce the chitosan molecular weight, benefiting its emulsification properties. The emulsion stability and emulsion type could be controlled by chitosan solution pH. Increasing pH from 3.5 to 5.5 led to the formation of conventional emulsions with decreasing droplet size (dv from 14 to 2.1 μm) and increasing emulsion stability (from a few days to 2 months). These results can be explained by the increase of dynamic interfacial pressure, which results from the conformation transition of chitosan molecules from an extended state to a more flexible structure as pH increases. At pH = 6.5 (the acid dissociation constant (pKa) of chitosan), the chitosan molecules self-assembled into well-dispersed nanoparticles (dv = 82.1 nm) with the assistance of ultrasonication, which resulted in a Pickering emulsion with the smallest droplet size (dv = 1.7 μm) and highest long-term stability (up to 5 months) because of the presence of chitosan solid nanoparticles at the oil/water interface. The key originality of this study is the elucidation of the role of pH in the formation of conventional and Pickering chitosan-based O/W emulsions with the assistance of ultrasonication. Our results suggest that chitosan possesses great potential to be used as an effective pH-controlled emulsifier and stabilizer without the need of other additives. PMID:26743171

  7. Encapsulation of functional lipophilic components in surfactant-based colloidal delivery systems: vitamin E, vitamin D, and lemon oil.

    PubMed

    Ziani, Khalid; Fang, Yuan; McClements, David Julian

    2012-09-15

    The fabrication and stability of surfactant-based colloidal delivery systems (microemulsions and emulsions) suitable for encapsulation of lipophilic active agents (vitamins and flavours) was investigated. An emulsion titration method was used to study the influence of surfactant type (Tween 20, 60 and 80) and oil type (Vitamin E, vitamin D(3) and lemon oil) on the incorporation of lipophilic components into surfactant micelles. Oil-in-water emulsions were formed and then different amounts were titrated into surfactant micelle solutions. The influence of surfactant-to-oil ratio (SOR) and oil type on the formation of colloidal dispersions was examined using dynamic light scattering and turbidity measurements. SOR, oil type, and surfactant type had a pronounced influence on the nature of the colloidal dispersions formed. Microemulsions could not be formed using vitamin D or E in 1% Tween solutions, due to the relatively large size of the lipophilic molecules relative to the hydrophobic interior of the surfactant micelles. On the other hand, microemulsions could be formed from lemon oil at relatively high SORs. There was not a major impact of non-ionic surfactant type (Tween 20, 60 or 80) on the formation and properties of the colloidal dispersions. However, Tween 20 micelles did appear to be able to solubilise less lemon oil than Tween 60 or 80 micelles, presumably due to their smaller dimensions. This study provides useful information for the rational design of food grade colloidal delivery systems for encapsulating flavour oils, oil-soluble vitamins, and other functional lipids for application in foods and beverages. PMID:23107734

  8. A cinnamic acid-type photo-cleavable surfactant.

    PubMed

    Sakai, Hideki; Aikawa, Shohei; Matsuda, Wataru; Ohmori, Takashi; Fukukita, Yuko; Tezuka, Yoji; Matsumura, Atsutoshi; Torigoe, Kanjiro; Tsuchiya, Koji; Arimitsu, Koji; Sakamoto, Kazutami; Sakai, Kenichi; Abe, Masahiko

    2012-06-15

    We have developed a novel cinnamic acid-type photo-cleavable surfactant. This surfactant experiences photo-cleavage through UV-induced cyclization in aqueous solutions. The photo-cleavage not only reduces its capabilities as a surfactant but also yields two functional materials including a coumarin derivative and an aminated polyoxyethylene compound. This means that the photo-cleavable surfactant synthesized in this study is a photo-responsive function-exchangeable material. In our current study, we have characterized the photo-cleavable behavior that occurs in aqueous solutions and a resulting change in interfacial properties. The photo-cleavage induces an increased interfacial tension of a squalane/water interface and a decreased solubilization capability of the surfactant micelles. PMID:22459027

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

    PubMed

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

    2013-06-01

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

  11. [Pulmonary surfactant system].

    PubMed

    Lazarov, S; Balutsov, M; Ianev, E

    2001-01-01

    The lung surfactant system (LSS) has a complex morphological and biochemical structure. LSS contains two components: cellular and non-cellular. The cellular component comprises three types of alveolar epithelium cells (type I, II, and II pneumocytes), alveolar macrophages (AM) and Clara bronchiolar cells. The non-cellular component consists of alveolar surfactant (AS), hypo(epi)phase and alveolar epithelium cell glycocalix. AS represents phospholipids, proteins and carbohydrates mono-molecular layer. AM lamellar bodies (LB) and tubular myelin (TM) are disposed in the hypophase. LB and TM represent the depot-forms of lung surfactant (LS). Lung surfactant (LS) has a complex biochemical structure and comprise the following components: phospholipids, neutral lipids, glycolipids, surfactant-specific proteins, plasmaproteins, enzymes, carbohydrates and aminoacids. LS is synthesized in type II pneumocytes and Clara cells. LS catabolism is mainly effected by AM. The LSS has a fundamental role in the physiological functions of lungs. Through its antiatelectatic and antioedematic functions, LSS sustains the basic physiological functions of lungs--alveolar ventilation and gas diffusion through the alveolar-capillary wall. Besides this, LSS performs several protecting functions--antioxidant defense, non-specific defense mechanisms, immunodulatory action, cytotoxicity agents metabolism and others. The injury of the structure and functions of LSS is an important pathogenic mechanism in the pathogenesis of different lung diseases. Practically, a pathological process in lungs, which is not related to changes in LSS structure and functions, does not exist. Recently developed surfactant replacement therapy with natural and synthetic surfactants has an important place in the therapy of several lung diseases. PMID:11785089

  12. 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

  13. Catalytic and structural properties of surfactant-horseradish peroxidase complex in organic media.

    PubMed

    Kamiya, N; Inoue, M; Goto, M; Nakamura, N; Naruta, Y

    2000-01-01

    A surfactant-horseradish peroxidase (HRP) complex that is catalytically active in organic media has been successfully prepared by a method utilizing water-in-oil (W/O) emulsions. To optimize conditions for preparation of the HRP complex, the effects of some key parameters in the aqueous phase of W/O emulsions were investigated. The surfactant-HRP complex prepared with a nonionic surfactant exhibited a high catalytic activity compared to those with a cationic or anionic surfactant in anhydrous benzene. At the preparation step, the pH of the aqueous solution had a prominent effect on the enzymatic activity of the HRP complex in organic media. Several kinds of salts present in the HRP complex could be employed to enhance the catalytic performance in organic media. However, anionic ions present in the preparation process appeared to lower the catalytic activity owing to the complexation with heme iron. UV-visible absorption spectra of the HRP complex in benzene, which were prepared from a KCN solution (pH 7.0) or an alkaline solution (pH 12), were comparable with those of native HRP in aqueous solution under the same conditions. Resonance Raman spectroscopic studies also revealed that no significant change in the coordination state of the heme iron occurred even after coating the enzyme with surfactant molecules, lyophilization, and solubilization in nonaqueous media. PMID:10662489

  14. Advances with holographic DESA emulsions

    NASA Astrophysics Data System (ADS)

    Dünkel, Lothar; Eichler, Jürgen; Schneeweiss, Claudia; Ackermann, Gerhard

    2006-02-01

    DESA emulsions represent layer systems based on ultra-fine grained silver halide (AgX) technology. The new layers have an excellent performance for holographic application. The technology has been presented repeatedly in recent years, including the emulsion characterization and topics of chemical and spectral sensitization. The paper gives a survey of actual results referring to panchromatic sensitization and other improvements like the application of silver halide sensitized gelatine (SHSG) procedure. These results are embedded into intensive collaborations with small and medium enterprises (SME's) to commercialize DESA layers. Predominant goals are innovative products with holographic components and layers providing as well as cost effectiveness and high quality.

  15. The influence of sulfate ion on the coal-wetting performance of anionic surfactants

    SciTech Connect

    Kilau, H.W.

    1990-01-01

    The Bureau of Mines is investigating surfactants added to water sprays to enhance the control of dust during coal mining operations. The objective of the present work was to establish the general applicability of adding sulfate ion to anionic surfactant solutions in order to improve wetting action. This was pursued through laboratory wettability testing of four anionic surfactants and one nonionic surfactant in combination with various concentrations of sulfate ion. The experimental results demonstrate that the addition of sulfate ion enhanced the wetting characteristics of all the anionic surfactants when applied to hard-to-wet coals, while easy-to-wet coal show more complex wetting behavior.

  16. Relaxation-induced coalescence with and without insoluble surfactants

    NASA Astrophysics Data System (ADS)

    Vannozzi, Carolina

    2014-11-01

    Rallison and Acrivos in 1978 investigated for the first time numerically the deformation and burst of a viscous drop in extensional flow. This seminal paper led to other important studies regarding the relaxation of viscous drops previously deformed in extensional flows, both for systems with and without surfactants. In this line of research we present the boundary integral simulations of the relaxation process of two viscous drops, previously undergoing a flow-induced head-on collision in an extensional flow, both with and without insoluble surfactants. The clean interface case showed that the acquired drop deformation induces a flow in the thin film between the drops as the interface relaxes back to restore the drop original shape. Under certain circumstances, this flow thins the film, allowing drop coalescence. Surprisingly, this phenomenon, the so-called relaxation-induced coalescence, is possible even for collisions which would not lead to coalescence while the flow is active, and it thus influences the final drop size distribution of blends/emulsions. In the presence of trace amounts of insoluble surfactants relaxation-induced coalescence is still possible, but less likely, depending strongly on the surfactant diffusivity.

  17. Hemolysis and antihemolysis induced by amino acid-based surfactants.

    PubMed

    Sánchez, Lourdes; Martínez, Verónica; Infante, M Rosa; Mitjans, Montserrat; Vinardell, M Pilar

    2007-03-01

    Surfactants have the special ability to interact with the lipid bilayer of cell membranes. The red blood cell is one of the most used cellular membrane models to study the mechanisms underlying surfactant-induced osmotic cell resistance. To increase our knowledge regarding the mechanisms of surfactant membrane interaction, we studied the action of five lysine-derivative anionic and three arginine-derivative cationic amino acid-based surfactants on hypotonic hemolysis. Results showed two different antihemolytic behaviors among amino acid-based surfactants, both related to the maximal protective concentration. How the physico-chemical properties and structure of these compounds determine the protection against hypotonic hemolysis is discussed in detail. We found a good correlation between the CMC and the concentrations resulting in maximum protection against hypotonic hemolysis for the cationic surfactants, but no correlation for the anionic surfactants. In the case of lysine derivative surfactants, which only differ in their counterions, the counterion is implicated in the differences in the antihemolytic potency and the hemolytic activities of this. PMID:17293064

  18. Nucleate pool boiling heat transfer in aqueous surfactant solutions

    NASA Astrophysics Data System (ADS)

    Wasekar, Vivek Mahadeorao

    Saturated, nucleate pool boiling in aqueous surfactant solutions is investigated experimentally. Also, the role of Marangoni convection, driven both by temperature and surfactant concentration gradients at the vapor-liquid interface of a nucleating bubble is computationally explored. Experimental measurements of dynamic and equilibrium sigma using the maximum bubble pressure method indicate dynamic sigma to be higher than the corresponding equilibrium value, both at room and elevated temperatures. Also, nonionic surfactants (Triton X-100, Triton X-305) show larger sigma depression than anionic surfactants (SDS, SLES), and a normalized representation of their dynamic adsorption isotherms is shown to be helpful in generalizing the surfactant effectiveness to reduce surface tension. The dynamic sigma has a primary role in the modification of bubble dynamics and associated heat transfer, and is dictated by the adsorption kinetics of the surfactant molecules at boiling temperatures. In general, an enhancement in heat transfer is observed, which is characterized by an early incipience and an optimum boiling performance at or around the critical micelle concentration of the surfactant. The optimum performances, typically in the fully developed boiling regime ( q''w > 100 kW/m2), show a reverse trend with respect to surfactant molecular weights M, i.e., higher molecular weight additives promote lower enhancement. Normalized boiling performance using the respective solution's dynamic sigma correlates heat transfer coefficient by M-0.5 for anionics and M 0 for nonionics. This has been shown to be brought about by the surfactant concentration and its interfacial activity in a concentration sublayer around the growing vapor bubble, which governs the bubble growth behavior through the mechanism of dynamic sigma. The ionic nature of the surfactant influences the thickness and molecular makeup of the enveloping sublayer, thereby affecting the bubble dynamics and boiling heat transfer. Finally, the computational modeling of Marangoni convection for boiling nuclei at short time transients shows similarity solutions for pure water, and reduced convection with a peak in circulation strength in the presence of surfactants. The peaking corresponds to the characteristic surfactant adsorption time, which has been shown to depend solely upon the surfactant bulk concentration. For the absence of surfactant surface convection, an enhancement in Marangoni convection is observed. Furthermore, for the investigated range of parameters and time scales, the surfactant adsorption at the interface is not characterized by the presence of a stagnant cap. (Abstract shortened by UMI.)

  19. Choline alkylsulfates--new promising green surfactants.

    PubMed

    Klein, Regina; Kellermeier, Matthias; Touraud, Didier; Müller, Eva; Kunz, Werner

    2013-02-15

    In this work we show how a new promising green and highly water-soluble surfactant can be designed based on recent progress in the knowledge of counterion-headgroup binding and crystallization behavior. The result is the combination of a most classical surfactant anion, dodecylsulfate (DS), with choline (Ch), a natural green cation. The advantage of the physiological metabolite choline is its bulky structure that prevents ChDS from easy crystallization and thus leads to a considerable lowering of the Krafft point down to 0°C. The counterion-headgroup binding is reflected by the aqueous phase behavior of ChDS. Conductivity, surface tension, and cryo-TEM measurements allow the characterization of the dilute micellar region, while the penetration scan technique enables the establishment of a preliminary aqueous phase diagram. In addition, the influence of different mono- and divalent salts on the solubility of ChDS is investigated. The results are compared to the alkali sulfate and alkylcarboxylate homologs, and reveal that ChDS is less sensitive towards addition of salts than, for instance, choline carboxylates due to an increased counterion-headgroup association. Further, cytotoxicity tests on HeLa and SK-Mel 28 cells are presented and compared to other surfactants, showing that ChDS is no more harmful than its sodium counterpart SDS. Taken together, our findings highlight that the harmless green cation choline is of great potential for the design of new surfactants. PMID:23200100

  20. 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.

  1. Surfactant-histidine-heme ternary complex as a simple artificial heme enzyme in organic media

    PubMed

    Kamiya; Goto; Furusaki

    1999-08-20

    A surfactant-heme complex which shows peroxidase activity in organic media has been prepared by a method utilizing water-in-oil (W/O) emulsions. Both the aqueous phase pH and the type of surfactant appeared to have prominent effect on the catalytic activity of the heme complex in benzene. The catalytic efficiency of the heme complex was enhanced more than ten times by adding histidine to the aqueous phase of W/O emulsions in the preparation process. The enhancement of peroxidase activity was observed only in a nonaqueous medium due to the increase of the effective concentration of histidine as an activator. In the present study, we propose a simple preparation method for an artificial heme enzyme which works in nonaqueous media. Copyright 1999 John Wiley & Sons, Inc. PMID:10397889

  2. Nature of the Intermicellar Interactions in Ethoxylated Polysorbate Surfactants with High Degrees of Ethoxylation.

    PubMed

    Penfold, J; Thomas, R K; Li, P X; Tucker, I; Petkov, J; Petkova, R E

    2016-02-01

    Ethoxylated polysorbate Tween nonionic surfactants are extensively used as foam and emulsion stabilizers and in aqueous solution form globular micelles. The ethoxylated polysorbate surfactants with higher degrees of ethoxylation than the Tween surfactants exhibit some interesting self-assembly properties. Small-angle neutron scattering, SANS, measurements have revealed intermicellar interactions which are more pronounced than the hard-sphere excluded volume interactions normally associated with nonionic surfactant micelles. The interactions are interpreted as arising from the partial charge on the ether oxygen of the ethylene oxide groups. This gives rise to an effective net negative charge on the micelles, which has been determined from the SANS data and zeta potential measurements. For degrees of ethoxylation of ⩽20, the effect is relatively small. The interaction increases with increasing ethoxylation such that for a degree of ethoxylation of 50 the interaction is comparable to that of ionic surfactant micelles. Unlike the intermicellar interaction in ionic surfactant micellar solutions, which results from the charge on the micelle arising from the partial binding of counterions, the interaction between ethoxthylated polysorbate surfactant micelles is unaffected by the addition of electrolyte. PMID:26785290

  3. Characterizing the Effect of Salt and Surfactant Concentration on the Counterion Atmosphere around Surfactant Stabilized SWCNTs Using Analytical Ultracentrifugation.

    PubMed

    Lam, Stephanie; Zheng, Ming; Fagan, Jeffrey A

    2016-04-26

    Accurate characterization of dispersed-phase nanoparticle properties such as density, size, solvation, and charge is necessary for their utilization in applications such as medicine, energy, and materials. Herein, analytical ultracentrifugation (AUC) is used to quantify bile salt surfactant adsorption on length sorted (7,6) single-wall carbon nanotubes (SWCNTs) as a function of bulk surfactant concentration and in the presence of varying quantities of a monovalent salt-sodium chloride. These measurements provide high precision adsorbed surfactant density values in the literature for only the second SWCNT structure to date and report the quantity of adsorbed surfactant across a broad range of bulk surfactant concentrations utilized in SWCNT dispersion processing. Second, the measurements presented herein unambiguously demonstrate, via AUC, a direct relation between the size of the counterion cloud around a surfactant-stabilized SWCNT and solution ionic strength. The results show that changes in the size of the counterion cloud around surfactant-stabilized SWCNT are attributable to electrostatic phenomenon and not to changes in the quantity of adsorbed surfactant with salt addition. These results provide important reference values for projecting SWCNT dispersion behavior as a function of solution conditions and extend the range of nanoparticle properties measurable via AUC. PMID:27031248

  4. Emulsion Chamber Technology Experiment (ECT)

    NASA Technical Reports Server (NTRS)

    Gregory, John C.; Takahashi, Yoshiyuki

    1996-01-01

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

  5. Controlling molecular transport in minimal emulsions

    PubMed Central

    Gruner, Philipp; Riechers, Birte; Semin, Benoît; Lim, Jiseok; Johnston, Abigail; Short, Kathleen; Baret, Jean-Christophe

    2016-01-01

    Emulsions are metastable dispersions in which molecular transport is a major mechanism driving the system towards its state of minimal energy. Determining the underlying mechanisms of molecular transport between droplets is challenging due to the complexity of a typical emulsion system. Here we introduce the concept of ‘minimal emulsions', which are controlled emulsions produced using microfluidic tools, simplifying an emulsion down to its minimal set of relevant parameters. We use these minimal emulsions to unravel the fundamentals of transport of small organic molecules in water-in-fluorinated-oil emulsions, a system of great interest for biotechnological applications. Our results are of practical relevance to guarantee a sustainable compartmentalization of compounds in droplet microreactors and to design new strategies for the dynamic control of droplet compositions. PMID:26797564

  6. Controlling molecular transport in minimal emulsions

    NASA Astrophysics Data System (ADS)

    Gruner, Philipp; Riechers, Birte; Semin, Benoît; Lim, Jiseok; Johnston, Abigail; Short, Kathleen; Baret, Jean-Christophe

    2016-01-01

    Emulsions are metastable dispersions in which molecular transport is a major mechanism driving the system towards its state of minimal energy. Determining the underlying mechanisms of molecular transport between droplets is challenging due to the complexity of a typical emulsion system. Here we introduce the concept of `minimal emulsions', which are controlled emulsions produced using microfluidic tools, simplifying an emulsion down to its minimal set of relevant parameters. We use these minimal emulsions to unravel the fundamentals of transport of small organic molecules in water-in-fluorinated-oil emulsions, a system of great interest for biotechnological applications. Our results are of practical relevance to guarantee a sustainable compartmentalization of compounds in droplet microreactors and to design new strategies for the dynamic control of droplet compositions.

  7. 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.

  8. Novel emulsions stabilized by pH and temperature sensitive microgels

    NASA Astrophysics Data System (ADS)

    Ngai, To; Auweter, Helmut; Behrens, Sven

    2006-03-01

    Poly(N-isopropylacrylamide-co-methacrylic acid) (PNIPAM-MAA) microgel particles in aqueous solution exhibit a volume phase transition that can be induced by changes of either pH or temperature. In the swollen state, these microgels self-assemble at an octanol-water interface and can be used to stabilize surfactant-free oil-in-water emulsions. This stabilizing efficiency is retained even in the collapsed state, provided that the microgels are fully charged. At very low charge (low pH), on the other hand, the microgels migrate completely into the oil phase, and the emulsion breaks. In an intermediate regime of practical interest the emulsion stability can be tuned by small adjustments of pH or temperature. Because of this unprecedented stability control, we believe that such stimulus-responsive charged microgels have a great potential for applications in the field of cosmetic or pharmaceutical formulations. Conceptually they belong to a new class of emulsifiers combining properties of both classical surfactants and solid particles.

  9. Drug nanoparticles by emulsion-freeze-drying via the employment of branched block copolymer nanoparticles.

    PubMed

    Wais, Ulrike; Jackson, Alexander W; Zuo, Yanming; Xiang, Yu; He, Tao; Zhang, Haifei

    2016-01-28

    A large percentage of drug compounds exhibit low water solubility and hence low bioavailability and therapeutic efficacy. This may be addressed by preparation of drug nanoparticles, leading to enhanced dissolution rate and direct use for treatment. Various methods have been developed to produce drug nanocrystals, including wet milling, homogenization, solution precipitation, emulsion diffusion, and the recently developed emulsion freeze-drying. The drawback for these methods may include difficult control in particles size, use of surfactants & polymer, and low ratio of drug to stabilizer. Here, biocompatible branched block copolymer nanoparticles with lightly-crosslinked hydrophobic core and hydrophilic surface groups are synthesized by the direct monomer-to-particle methodology, characterized, and then used as scaffold polymer/surfactant to produce drug nanoparticles via the emulsion-freeze-drying approach. This method can be used for model organic dye and different poorly water-soluble drugs. Aqueous drug nanoparticle dispersions can be obtained with high ratio of drug to stabilizer and relatively uniform nanoparticle sizes. PMID:26704935

  10. Solution properties and emulsification properties of amino acid-based gemini surfactants derived from cysteine.

    PubMed

    Yoshimura, Tomokazu; Sakato, Ayako; Esumi, Kunio

    2013-01-01

    Amino acid-based anionic gemini surfactants (2C(n)diCys, where n represents an alkyl chain with a length of 10, 12, or 14 carbons and "di" and "Cys" indicate adipoyl and cysteine, respectively) were synthesized using the amino acid cysteine. Biodegradability, equilibrium surface tension, and dynamic light scattering were used to characterize the properties of gemini surfactants. Additionally, the effects of alkyl chain length, number of chains, and structure on these properties were evaluated by comparing previously reported gemini surfactants derived from cystine (2C(n)Cys) and monomeric surfactants (C(n)Cys). 2C(n)diCys shows relatively higher biodegradability than does C(n)Cys and previously reported sugar-based gemini surfactants. Both critical micelle concentration (CMC) and surface tension decrease when alkyl chain length is increased from 10 to 12, while a further increase in chain length to 14 results in increased CMC and surface tension. This indicates that long-chain gemini surfactants have a decreased aggregation tendency due to the steric hindrance of the bulky spacer as well as premicelle formation at concentrations below the CMC and are poorly packed at the air/water interface. Formation of micelles (measuring 2 to 5 nm in solution) from 2C(n)diCys shows no dependence on alkyl chain length. Further, shaking the mixtures of aqueous 2C(n)diCys surfactant solutions and squalane results in the formation of oil-in-water type emulsions. The highly stable emulsions are formed using 2C₁₂diCys or 2C₁₄diCys solution and squalane in a 1:1 or 2:1 volume ratio. PMID:23985487

  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. Partitioning of Laponite Clay Platelets in Pickering Emulsion Polymerization.

    PubMed

    Brunier, Barthélémy; Sheibat-Othman, Nida; Chevalier, Yves; Bourgeat-Lami, Elodie

    2016-01-12

    Partitioning of laponite disklike clay platelets between polymer particles and bulk aqueous phase was investigated in Pickering surfactant-free emulsion polymerization of styrene. Adsorption of laponite clay platelets plays an important role in the stabilization of this system, influencing the particle size and the number of particles, and, hence, the reaction rate. Adsorption isotherms show that, while the laponite clay platelets are almost fully exfoliated in water, they form multilayers on the surface of the polymer particles by the end of polymerization, as confirmed by transmission electron microscopy (TEM). This observation is supported by quartz crystal microbalance, conductivity, and TEM measurements, which reveal interactions between the clay and polystyrene, as a function of the ionic strength. The strong adsorption of clay platelets leaves a low residual concentration in the aqueous phase that cannot cause further nucleation of polymer particles, as demonstrated during seeded emulsion polymerization experiments in the presence of a high excess of clay. A Brunauer-Emmett-Teller (BET)-type model for laponite adsorption on polystyrene particles matches the adsorption isotherms. PMID:26653971

  13. Relationships between the properties of self-emulsifying pellets and of the emulsions used as massing liquids for their preparation.

    PubMed

    Nikolakakis, Ioannis; Panagopoulou, Athanasia; Salis, Andrea; Malamataris, Stavros

    2015-02-01

    Self-emulsifying pellets were prepared using microcrystalline cellulose, emulsions of caprylic/capric triglyceride, and three Cremophors (ELP, RH40, and RH60) at 1.5 and 2.3 weight ratios, and two drugs (furosemide and propranolol) of different lipophilicity. Droplet size, zeta potential (ζ) and viscosity of emulsions, and pellet size, shape, friability, tensile strength, disintegration, and drug migration in pellets were determined. Evaluation of reconstituted emulsions was based on droplet size and ζ. Factorial design and 3-way ANOVA was applied to estimate the significance of the effects of the drug, surfactant and oil/surfactant ratio. It was found that droplet size, viscosity and ζ of emulsions, and size, shape, and friability of pellets were affected by the studied factors and were significant interactions between their effects on pellet size and friability. Migration of drug towards the pellet surface was higher for the less lipophilic furosemide and higher oil content. Linear relationships were found between the emulsion viscosity and the shape parameters of the pellets (for the aspect ratio R (2) = 0.796 for furosemide and R (2) = 0.885 for propranolol and for the shape factor, e R R (2) = 0.740 and R (2) = 0.960, respectively). For all the formulations examined, an exponential relationship was found between migration (M%) and the product of viscosity (η) and solubility of drug in oil/surfactant mixture (S) (M% = 98.1e-0.016 [η•S], R (2) = 0.856), which may be useful in formulation work. PMID:25212898

  14. Effects of emulsion gels containing bioactive compounds on sensorial, technological, and structural properties of frankfurters.

    PubMed

    Pintado, T; Herrero, A M; Ruiz-Capillas, C; Triki, M; Carmona, P; Jiménez-Colmenero, F

    2016-03-01

    Emulsion gels prepared with olive oil, chia, and cold gelling agents (transglutaminase, alginate, or gelatin) were used as fat replacers in reduced-fat frankfurter formulation. Nutritional advantages, sensory analysis, technological properties, and microbiological populations of frankfurters were evaluated along with their lipid structural characteristics over chilled storage. Frankfurters with emulsion gels showed significant improvements in fat content (lower saturated fatty acid, higher mono- and polyunsaturated fatty acid contents) and had good fat and water-binding properties. The presence of an emulsion gel reduced lightness and redness, but increased yellowness. Textural behavior of samples was significantly affected by the presence of emulsion gels and by storage. Sensory properties were not affected by the incorporation of emulsion gels, and all frankfurters were judged acceptable. Attenuated total reflectance-Fourier transform infrared spectroscopy results showed that samples with emulsion gels involve more lipid-protein interactions. Frankfurters with emulsion gels showed good stability to oxidation during storage and contained lower levels of microorganism than reduced-fat control at 85 days. PMID:25788169

  15. 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

  16. Magnetization reversal behavior of SmCo6.6Nb0.4 nanoflakes prepared by surfactant-assisted ball milling

    NASA Astrophysics Data System (ADS)

    Li, Y. Q.; Yue, M.; Wu, Q.; Liu, W. Q.; Zhang, D. T.; Lu, Q. M.

    2016-05-01

    In this paper, the recoil loops of SmCo6.6Nb0.4 nanoflakes prepared by the surfactant-assisted high energy ball milling (SA-HEBM) were systematically studied. The recoil loop openness was observed in both the aligned and non-aligned samples. Reversible and irreversible portions of the demagnetization process derived from the recoil loop were also investigated. For both the aligned and non-aligned samples, reversible portion (▵mrev) is too small to determine the coercivity. Irreversible portion (▵mirrev) shows similar tendency, i.e. increasing slowly at low reverse field and then growing up rapidly after a critical field (nucleation field Hno). The demagnetization process can be described as following: the reversible demagnetization is dominant when the applied reverse field is lower than 8 kOe, under which the irreversible nucleation also occurs. The reverse domain walls are pinned by the grain boundaries until the reverse field is larger than 8 kOe. With increasing field, the pinning effects are weakened and the rapid reversible demagnetization starts. Finally, the demagnetization process is accomplished. The values of ΔM in the Henkel plots are totally opposite for the aligned and non-aligned SmCo6.6Nb0.4 nanoflakes.

  17. Microencapsulation of rosmarinic acid using polycaprolactone and various surfactants.

    PubMed

    Kim, H-J; Kim, T-H; Kang, K-C; Pyo, H-B; Jeong, H-H

    2010-06-01

    Rosmarinic acid (RA) has a number of interesting biological activities, e.g. anti-viral, anti-bacterial, anti-inflammatory and antioxidant. The antioxidant activity of RA is stronger than that of vitamin E. Despite its strong antioxidant activity, it was limited to use in cosmetics because of the low water solubility, discolouration and chemical instability. The purpose of this study was to prepare RA-loaded polycaprolactone (PCL) microspheres using emulsion solvent evaporation method and characterize them with different surfactants used in the formation process. Finally, long-term stability of RA was evaluated in the cosmetic formulation. As a result, PCL microspheres were found to be spherical in shape, with zwitterionic surfactant-PCL particles being the smallest size distribution and highest entrapment efficiency of RA. Emulsions containing RA-loaded PCL microspheres showed a better long-term stability of the RA compared with those containing only RA. These results suggest that RA may be stably and efficiently encapsulated into polycaprolactone microspheres. PMID:20557576

  18. Sorption of perchloroethylene by surfactant-modified zeolite as controlled by surfactant loading

    SciTech Connect

    Li, Z.; Bowman, R.S.

    1998-08-01

    The sorption of nonpolar hydrophobic organic compounds by soil organic matter has long been attributed to a partitioning mechanism, with the sorption coefficient proportional to the fractional organic carbon content of the soil. However, deviations from this linear proportionality have been observed and reported in the literature by many authors. In the study a natural zeolite was modified with a cationic surfactant to achieve different fractional organic carbon contents and different surfactant molecule configurations on the surface. The sorption of perchloroethylene (PCE) by the surfactant-modified zeolite (SMZ) was found to be dependent on the bound surfactant molecule configuration as well as on the fractional organic carbon content. Below monolayer coverage by the surfactant, the PCE sorption coefficient on SMZ was proportional to the fractional organic carbon content. Above monolayer coverage, increasing fractional organic carbon content resulted in minimal further increase in the PCE sorption coefficient. The change in PCE sorption behavior was attributed to the structural differences between sorbed surfactant monolayers and bilayers. The surfactant surface configuration has a significant impact on the effective volume and density of the bound organic phase that is responsible for partitioning nonpolar organic compounds. The ratio of the organic carbon-based distribution coefficient (K{sub oc}) for the monolayer versus that for the bilayer systems was 1.7, similar to the estimated bilayer to monolayer hydrocarbon density of 1.3. The results reinforce the notion that the structure of natural organic matter as well as its quantity controls the sorption of nonpolar organics to soils and sediments.

  19. Surfactant-enhanced bioremediation

    SciTech Connect

    Churchill, P.F.; Dudley, R.J.; Churchill, S.A.

    1995-12-31

    This study was undertaken to examine the effect of three structurally related, non-ionic surfactants, Triton X-45, Triton X-100 and Triton X-165, as well as the oleophilic fertilizer, Inipol EAP 22, on the rate of biodegradation of phenanthrene by pure bacterial cultures. Each surfactant dramatically increased the apparent aqueous solubility of phenanthrene. Model studies were conducted to investigate the ability of these surfactants to enhance the rate of transport and uptake of polycyclic aromatic hydrocarbons into bacterial cells, and to assess the impact that increasing the aqueous solubility of hydrocarbons has on their rate of biodegradation. The results indicate that increasing the apparent aqueous solubility of hydrocarbons can lead to enhanced biodegradation rates by two Pseudomonas saccharophila strains. However, the experiments also suggest that some surfactants can inhibit aromatic hydrocarbon biodegradation by certain bacteria. The data also support the hypothesis that surface-active components present in the oleophilic fertilizer formulation, Inipol EAP 22, may have significantly contributed to the positive results reported in tests of remedial agent impact on bioremediation, which was used as a supplemental clean-up technology on Exxon Valdez crude oil-contaminated Alaskan beaches.

  20. 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.

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

    PubMed

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

    2007-02-01

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

  2. 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

  3. 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

  4. Enhancement of aqueous stability of allyl isothiocyanate using nanoemulsions prepared by an emulsion inversion point method.

    PubMed

    Li, Ying; Teng, Zi; Chen, Pei; Song, Yingying; Luo, Yangchao; Wang, Qin

    2015-01-15

    Allyl isothiocyanate (AITC), an organosulfur compound in cruciferous vegetables, is a natural antimicrobial and potential chemopreventive agent. However, the instability of AITC in aqueous systems restrains its applications. In this study, oil-in-water AITC nanoemulsion was prepared by the emulsion inversion point (EIP) method, aiming at improving the aqueous stability of AITC. The optimal hydrophilic-lipophilic balance (HLB(op)) value of surfactants containing Tween 80 and Span 80 was established at 11.0-13.0, yielding nanodroplets with diameters of 137-215 nm. The mechanism of droplet formation within the HLP(op) region was discussed in terms of the possible structure of adsorbed surfactant layers at the oil-water interface in multiple emulsion droplets. In a 6.5-month storage test, the droplet sizes and the count rates (intensity of scattered light) of nanoemulsions decreased only slightly by 4-13% (depending on surfactant-to-oil ratio), even in highly diluted status, indicating the desirable stability of the nanoemulsions. Moreover, the nanoemulsion demonstrated superior protection against AITC degradation (78% remaining after 60 d at 30 °C), compared with protein nanoparticles as well as non-encapsulated aqueous dispersion. This work shows for the first time that AITC can be formulated into nanoemulsions and thus obtains satisfactory aqueous solubility and chemical stability. PMID:25454435

  5. 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

  6. Magnetic surfactants as molecular based-magnets with spin glass-like properties.

    PubMed

    Brown, Paul; Smith, Gregory N; Hernández, Eduardo Padrón; James, Craig; Eastoe, Julian; Nunes, Wallace C; Settens, Charles M; Hatton, T Alan; Baker, Peter J

    2016-05-01

    This paper reports the use of muon spin relaxation spectroscopy to study how the aggregation behavior of magnetic surfactants containing lanthanide counterions may be exploited to create spin glass-like materials. Surfactants provide a unique approach to building in randomness, frustration and competing interactions into magnetic materials without requiring a lattice of ordered magnetic species or intervening ligands and elements. We demonstrate that this magnetic behavior may also be manipulated via formation of micelles rather than simple dilution, as well as via design of surfactant molecular architecture. This somewhat unexpected result indicates the potential of using novel magnetic surfactants for the generation and tuning of molecular magnets. PMID:27028571

  7. Magnetic surfactants as molecular based-magnets with spin glass-like properties

    NASA Astrophysics Data System (ADS)

    Brown, Paul; Smith, Gregory N.; Padrón Hernández, Eduardo; James, Craig; Eastoe, Julian; Nunes, Wallace C.; Settens, Charles M.; Hatton, T. Alan; Baker, Peter J.

    2016-05-01

    This paper reports the use of muon spin relaxation spectroscopy to study how the aggregation behavior of magnetic surfactants containing lanthanide counterions may be exploited to create spin glass-like materials. Surfactants provide a unique approach to building in randomness, frustration and competing interactions into magnetic materials without requiring a lattice of ordered magnetic species or intervening ligands and elements. We demonstrate that this magnetic behavior may also be manipulated via formation of micelles rather than simple dilution, as well as via design of surfactant molecular architecture. This somewhat unexpected result indicates the potential of using novel magnetic surfactants for the generation and tuning of molecular magnets.

  8. Diseases of Pulmonary Surfactant Homeostasis

    PubMed Central

    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

  9. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-01-01

    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. We have acquired field oil and core samples and field brine compositions from Marathon. We have conducted preliminary adsorption and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Receding contact angles increase with surfactant adsorption. Plans for the next quarter include conducting adsorption, phase behavior and wettability studies.

  10. Optimization of a gelled emulsion intended to supply ?-3 fatty acids into meat products by means of response surface methodology.

    PubMed

    Poyato, Candelaria; Ansorena, Diana; Berasategi, Izaskun; Navarro-Blasco, Iigo; Astiasarn, Iciar

    2014-12-01

    The optimization of a gelled oil-in-water emulsion was performed for use as fat replacer in the formulation of ?-3 PUFA-enriched cooked meat products. The linseed oil content, carrageenan concentration and surfactant-oil ratio were properly combined in a surface response design for maximizing the hardness and minimizing the syneresis of the PUFA delivery system. The optimal formulation resulted in a gelled emulsion containing 40% of oil and 1.5% of carrageenan, keeping a surfactant-oil ratio of 0.003. The gel was applied as a partial fat replacer in a Bologna-type sausage and compared to the use of an O/W emulsion also enriched in ?-3. Both experimental sausages contributed with higher ?-3 PUFA content than the control. No sensory differences were found among formulations. The selected optimized gelled oil-in-water emulsion was demonstrated to be a suitable lipophilic delivery system for ?-3 PUFA compounds and applicable in food formulations as fat replacer. PMID:25089785

  11. Saponins: a renewable and biodegradable surfactant from its microwave-assisted extraction to the synthesis of monodisperse lattices.

    PubMed

    Schmitt, C; Grassl, B; Lespes, G; Desbrières, J; Pellerin, V; Reynaud, S; Gigault, J; Hackley, V A

    2014-03-10

    Synthetic surfactants are widely used in emulsion polymerization, but it is increasingly desirable to replace them with naturally derived molecules with a reduced environmental burden. This study demonstrates the use of saponins as biodegradable and renewable surfactants for emulsion polymerization. This chemical has been extracted from soapnuts by microwave assisted extraction and characterized in terms of surfactant properties prior to emulsion polymerization. The results in terms of particle size distribution and morphology control have been compared to those obtained with classical nonionic (NP40) or anionic (SDS) industrial surfactants. Microwave-extracted saponins were able to lead to latexes as stable as standard PS latex, as shown by the CMC and CCC measurements. The saponin-stabilized PS particles have been characterized in terms of particle size and distribution by Dynamic Light Scattering and Asymmetrical Flow Field Flow Fractionation. Monomodal and monodispersed particles ranging from 250 to 480 nm in terms of diameter with a particle size distribution below 1.03 have been synthesized. PMID:24443771

  12. Dynamics of Sheared Polydisperse Emulsions

    NASA Astrophysics Data System (ADS)

    Du, Xin; Desmond, Kenneth; Chen, Dandan; Edmond, Kazem; Weeks, Eric

    2012-02-01

    Polydispersity is an important parameter in the jamming transition of soft materials which has not been well understood yet. In our work, we study the elastic response of a high volume fraction polydisperse emulsion to a periodic shear stress. The droplets' dynamics is imaged by confocal microscopy. Our results reveal that most of the droplets in the emulsion exhibit an elastic and periodic motion under the shear stress. However, the smaller droplets often move with anomalously large or small amplitudes compared to the mean motion. Some droplets also move nearly perpendicular to the mean flow field. The broad distribution of the amplitudes and phases of the smaller droplets' motions can be attributed to the motion the larger droplets and the distribution of the droplet sizes.

  13. Emulsion PCR: Techniques and Applications.

    PubMed

    Kanagal-Shamanna, Rashmi

    2016-01-01

    Emulsion PCR (EmPCR) is a commonly employed method for template amplification in multiple NGS-based sequencing platforms. The basic principle of emPCR is dilution and compartmentalization of template molecules in water droplets in a water-in-oil emulsion. Ideally, the dilution is to a degree where each droplet contains a single template molecule and functions as a micro-PCR reactor. Here, we discuss the basic principles, advantages, and challenges of applications of emPCR in clinical testing. We describe the methods of preparation and enrichment of template-positive Ion PGM™ Template OT2 200 Ion Sphere™ Particles (ISPs) on the Ion Personal Genome Machine(®) (PGM™) System. For routine clinical testing, following library generation, we employ the automated Ion OneTouch™ System that includes the Ion OneTouch™ 2 and the Ion OneTouch™ ES instruments for template generation and enrichment of template-positive ISPs, respectively. PMID:26843044

  14. Development and evaluation of emulsion-liposome blends for resveratrol delivery.

    PubMed

    Hung, Chi-Feng; Chen, Jan-Kan; Liao, Mei-Hui; Lo, Huey-Ming; Fang, Jia-You

    2006-01-01

    Nano- and submicron-sized vesicles are beneficial for the controlled delivery of drugs. Resveratrol, the main active polyphenol in red wine, was incorporated into various combinations of emulsions and liposomes to examine its physicochemical characteristics and cardiovascular protection. The blends of emulsion-liposome were composed of coconut oil, soybean lecithin, glycerol formal, and non-ionic surfactants. Multiple systems were assessed by evaluating the droplet size, surface charge, drug encapsulation, release rate, and stability. The vesicle diameter of the systems ranged from 114 to 195 nm. The liposomal vesicles in the systems had smaller diameters (of 43 approximately 56 nm) (F6 and F7). Drug encapsulation of approximately 70% were achieved by the vesicles. The inclusion of resveratrol in these systems retarded the drug release in both the presence and absence of plasma in vitro. The emulsion-liposome blends which incorporated Brij 98 (F5) exhibited the slowest release at zero-order for resveratrol delivery. Treatment using resveratrol in the blended formulations dramatically inhibited vascular intimal thickening, which was tested in an experimental model in which endothelial injury was produced in normal rat carotid arteries. Intraperitoneal injection of the multiple systems was associated with no or negligible liver and kidney toxicity. We concluded that encapsulation by the emulsion-liposome blends is a potent way to enhance the preventative and therapeutic benefits of resveratrol. PMID:17048503

  15. Double emulsions based on silicone-fluorocarbon-water and their skin penetration.

    PubMed

    Mahrhauser, Denise-Silvia; Fischer, Claudia; Valenta, Claudia

    2016-02-10

    Double emulsions have significant potential in pharmacy and cosmetics due to the feasibility of combining incompatible substances in one product and the protection of sensitive compounds by incorporating them into their innermost phase. However, a major drawback of double emulsions is their thermodynamic instability and their strong tendency to coalesce. In the present study, the physicochemical stability, the skin permeation and the skin penetration potential of modified semi-solid double emulsions was investigated. The double emulsions were prepared of the cosmetically applied perfluoropolyethers Fomblin(®) HC/04 or Fomblin(®) HC-OH, silicone, carbomer and water. Measurement of the droplet size and examination of the microscopic images confirmed their physicochemical stability over the observation period of eight weeks. Franz-type diffusion cell experiments revealed no increase in curcumin permeation due to the employed perfluoropolyethers compared to the respective control formulations. The formulations used as control were O/W macroemulsions with or without a Polysorbate 80/Sorbitane monooleate 80 surfactant combination. Likewise, tape stripping studies showed no penetration enhancing effect of the employed perfluoropolyethers which is desirable as both perfluoropolyethers are commonly applied components in human personal-care products. PMID:26688033

  16. Block copolymer stabilized nonaqueous biocompatible sub-micron emulsions for topical applications.

    PubMed

    Atanase, Leonard Ionut; Riess, Gérard

    2013-05-20

    Polyethylene glycol (PEG) 400/Miglyol 812 non-aqueous sub-micron emulsions were developed due to the fact that they are of interest for the design of drug-loaded biocompatible topical formulations. These types of emulsions were favourably stabilized by poly (2-vinylpyridine)-b-poly (butadiene) (P2VP-b-PBut) copolymer with DPBut>DP2VP, each of these sequences being well-adapted to the solubility parameters of PEG 400 and Miglyol 812, respectively. This type of block copolymers, which might limit the Ostwald ripening, appeared to be more efficient stabilizers than low molecular weight non-ionic surfactants. The emulsion characteristics, such as particle size, stability and viscosity at different shear rates were determined as a function of the phase ratio, the copolymer concentration and storage time. It was further shown that Acyclovir, as a model drug of low water solubility, could be incorporated into the PEG 400 dispersed phase, with no significant modification of the initial emulsion characteristics. PMID:23566926

  17. Development of pH responsive novel emulsion adjuvant for oral immunization and in vivo evaluation.

    PubMed

    Malik, Basant; Gupta, Ravi Kumar; Rath, Goutam; Goyal, Amit K

    2014-08-01

    The present work has been envisaged to develop a pH responsive multiple emulsion (W/O/W) adjuvant for successful antigen delivery via oral route. The formulation was prepared by double emulsion technique using squalene as oil phase and a combination of antigens and Quil A as internal aqueous phase. Squalene emulsion (O/W) adjuvants are well accepted for parenteral administration. Instead of using conventional surfactants, Quil A was incorporated in the internal aqueous compartment for the first time. The microscopic analysis confirmed the formation of the W/O/W multiple emulsions with globule diameter ranging from 7 to 12 μm. Considerably, addition of Quil A resulted in marked improvement in both in vitro stability and immune response. Furthermore, addition of pectin to the external aqueous phase resulted in improved in vitro stability. A formulation with gel like structure was formed when pectin was used as stabilizer and also accounted with a significant increase in viscosity (from 275.3 cP to 330.4 cP) in the simulated gastric fluid, which reverts back to 290.2 cP after exposure to simulated intestinal fluid. Induction of strong mucosal and systemic immune response suggested that the developed formulation could be useful for the delivery of multiple biomolecules via oral route. PMID:24681295

  18. Sublethal effect of agronomical surfactants on the spider Pardosa agrestis.

    PubMed

    Niedobová, Jana; Hula, Vladimír; Michalko, Radek

    2016-06-01

    In addition to their active ingredients, pesticides contain also additives - surfactants. Use of surfactants has been increasing over the past decade, but their effects on non-target organisms, especially natural enemies of pests, have been studied only very rarely. The effect of three common agrochemical surfactants on the foraging behavior of the wolf spider Pardosa agrestis was studied in the laboratory. Differences in short-term, long-term, and overall cumulative predatory activities were investigated. We found that surfactant treatment significantly affected short-term predatory activity but had no effect on long-term predatory activity. The surfactants also significantly influenced the cumulative number of killed prey. We also found the sex-specific increase in cumulative kills after surfactants treatment. This is the first study showing that pesticide additives have a sublethal effect that can weaken the predatory activity of a potential biological control agent. More studies on the effects of surfactants are needed to understand how they affect beneficial organisms in agroecosystems. PMID:26878602

  19. Magnetic Surfactants and Polymers with Gadolinium Counterions for Protein Separations.

    PubMed

    Brown, Paul; Bromberg, Lev; Rial-Hermida, M Isabel; Wasbrough, Matthew; Hatton, T Alan; Alvarez-Lorenzo, Carmen

    2016-01-26

    New magnetic surfactants, (cationic hexadecyltrimethlyammonium bromotrichlorogadolinate (CTAG), decyltrimethylammonium bromotrichlorogadolinate (DTAG), and a magnetic polymer (poly(3-acrylamidopropyl)trimethylammonium tetrachlorogadolinate (APTAG)) have been synthesized by the simple mixing of the corresponding surfactants and polymer with gadolinium metal ions. A magnetic anionic surfactant, gadolinium tri(1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate) (Gd(AOT)3), was synthesized via metathesis. Both routes enable facile preparation of magnetically responsive magnetic polymers and surfactants without the need to rely on nanocomposites or organic frameworks with polyradicals. Electrical conductivity, surface tensiometry, SQUID magnetometry, and small-angle neutron scattering (SANS) demonstrate surface activity and self-aggregation behavior of the magnetic surfactants similar to their magnetically inert parent analogues but with added magnetic properties. The binding of the magnetic surfactants to proteins enables efficient separations under low-strength (0.33 T) magnetic fields in a new, nanoparticle-free approach to magnetophoretic protein separations and extractions. Importantly, the toxicity of the magnetic surfactants and polymers is, in some cases, lower than that of their halide analogues. PMID:26725503

  20. Surfactant remediation field demonstration using a vertical circulation well

    SciTech Connect

    Knox, R.C.; Sabatini, D.A.; Harwell, J.H.; Brown, R.E.; West, C.C.; Blaha, F.; Griffin, C.

    1997-11-01

    A field demonstration of surfactant-enhanced solubilization was completed in a shallow unconfined aquifer located at a Coast Guard Station in Traverse City, Michigan. The primary objectives of the study were: (1) to assess the ability of the vertical circulation well (VCW) system for controlling chemical extractants added to the subsurface; and (2) to assess the behavior of the surfactant solution in the subsurface, with a goal of maximum surfactant recovery. A secondary objective was to demonstrate enhanced removal of PCE and recalcitrant components of a jet fuel. The analytical results showed that the surfactant increased the contaminant mass extracted by 40-fold and 90-fold for the PCE and jet fuel constituents, respectively. The surfactant solution demonstrated minimal sorption (retardation) and did not precipitate in the subsurface formation. In addition, the VCW system was able to capture in excess of 95% of the injected surfactant solution. Additional field testing and full-scale implementation of surfactant-enhanced subsurface remediation should be performed.

  1. Preparation and characterization of narrow sized (o/w) magnetic emulsion

    NASA Astrophysics Data System (ADS)

    Montagne, F.; Mondain-Monval, O.; Pichot, C.; Mozzanega, H.; Elaı̈ssari, A.

    2002-09-01

    The preparation of well-defined (o/w) magnetic emulsions from an organic ferrofluid is reported. The ferrofluid synthesis is first described and a complete characterization is achieved by using numerous techniques. The ferrofluid is found to be composed of superparamagnetic maghemite nanoparticles, with a diameter below 10 nm, stabilized in octane by a surrounding oleic acid layer. This magnetic fluid is then emulsified in aqueous media in order to obtain stable ferrofluid droplets. The use of a couette mixer and a size sorting step under magnetic field allowed to produce magnetic emulsion with a narrow size distribution. Morphology and chemical composition of the magnetic emulsion are investigated. Magnetic properties of both ferrofluid and magnetic emulsion are also compared and discussed. In particular, it is showed that the superparamagnetic behavior is still observed after the emulsification process.

  2. Treatment of coal tar emulsions

    SciTech Connect

    Cukier, S.

    1983-07-26

    The present invention relates to a process for the treatment of stable emulsions of water and quinoline insolubles in coal tar comprising thoroughly mixing the coal tar with at least one of a specific class of surface-active compositions, followed by a separation of water and quinoline insoluble components from the mixture. The invention also relates to a method of eliminating or minimizing the build-up of coal tar-derived deposits on surfaces in contact with the coal tar.

  3. Resonant ultrasonic attenuation in emulsions

    NASA Astrophysics Data System (ADS)

    Brunet, Thomas; Mascaro, Benoit; Poncelet, Olivier; Aristégui, Christophe; Raffy, Simon; Mondain-Monval, Olivier; Leng, Jacques

    2013-08-01

    We report the achievement of scattering resonant emulsions devoted to the frequency-control of acoustic attenuation in the megahertz range. By means of robotics, we produced highly monodisperse, in both size and shape, fluorinated-oil droplet suspensions, providing experimental evidence of several Mie scattering resonances. Ultrasonic experiments performed in such complex media are compared, with an excellent quantitative agreement, to theoretical predictions derived within the framework of the independent scattering approximation.

  4. Changing Emulsion Dynamics with Heterogeneous Surface Wettability

    NASA Astrophysics Data System (ADS)

    Tsai, Peichun Amy; Meng, Qiang; Zhang, Yali; Li, Jiang; Lammertink, Rob; Chen, Haosheng

    2015-11-01

    We elucidate the effect of heterogeneous surface wettability on the morphology and dynamics of microfluidic emulsions, generated by a co-flowing device. We first design a useful methodology of modifying a micro-capillary with desired heterogeneous wettability, such as alternating hydrophilic and hydrophobic regions. Subsequently, the effects of flow rates and heterogeneous wettability on the emulsion morphology and motion in the micro-capillary are investigated. Our experimental data reveal a universal critical time scale of advective emulsions, above which the microfluidic emulsions remain intact, whereas below this time-scale emulsions become adhesive or inverse. A simple model based on a force balance can be used to explain this critical transition. These results show a control of emulsion dynamics by tuning the droplet size and the Capillary number, the ratio of viscous to surface effects, with heterogeneous surface wettability.

  5. 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

  6. Experiment S009: Nuclear Emulsion

    NASA Technical Reports Server (NTRS)

    Odell, F. W.; Shapiro, M. M.; Silberberg, R.; Stiller, B.; Tsao, C. H.; Durgaprasad, N.; Fichtel, C. E.; Guss, D. E.; Reames, D. V.

    1971-01-01

    The first exposure on a spacecraft of a nuclear emulsion apparatus designed to collect 1000 high quality tracks of heavy nuclei under a negligible thickness of matter (0.07 g/sq cm) is described. The cosmic ray detector consisted of a stack of nuclear emulsions that were designed to register at least 400 heavy nuclei tracks for each 10 hours of useful exposure. The spacecraft had to be oriented in a heads-up attitude during the 10-hour period to eliminate atmospheric albedo particles. The results are as follows: (1) a definite odd-even effect, with low abundances for elements of atomic number 7, 9, and 11; (2) a ratio O/C approximately 0.9; (3) Ne/C, Mg/C, and Si/C ratios between 0.2 and 0.3; (4) an abundance gap in the region 15 less than or equal to Z less than or equal to 19; and (5) a ratio (20 less than or equal to Z less than or equal to 28)/C 0.2, with a large concentration at Z = 26. These results are indicative that successful exposures of nuclear emulsions were obtained on the Gemini 11 mission.

  7. A Novel Monodisperse Emulsion Generator

    NASA Astrophysics Data System (ADS)

    Umbanhowar, P. B.; Weitz, D. A.

    1998-03-01

    A simple mechanical device for the production of emulsions with droplet sizes ranging from 1 to 100 μm and with typical droplet polydispersity of less than 4 percent will be described. The device consists of a micro-pipette with diameter less than or comparable to the desired droplet size and a rotating cylindrical container. The continuous phase of the emulsion is placed in the container and the micro-pipette brought into contact with the rotating fluid. The fluid to be dispersed is slowly forced through the micro-pipette; droplets detach from the tip when the drag force exceeds the interfacial tension. Droplet size is determined by the tip diameter, interfacial tension, continuous phase viscosity, and flow velocity, but not the extrusion rate as long as it is kept below the critical rate for jet formation. In general, any dispersed phase that forms a stable emulsion can be used. However, to avoid the formation of small satellite droplets, the viscosity ratio of the dispersed to the continuous phase should be small. High viscosity fluids can be dispersed by mixing them with low viscosity solvents which diffuse into and then evaporate from the continuous phase.

  8. Transdermal delivery of an anti-cancer drug via w/o emulsions based on alkyl polyglycosides and lecithin: design, characterization, and in vivo evaluation of the possible irritation potential in rats.

    PubMed

    ElMeshad, Aliaa Nabil; Tadros, Mina Ibrahim

    2011-03-01

    The purpose of this work was to develop w/o emulsions that could be safely used to promote transdermal delivery of 5-fluorouracil (5-FU). Two pseudo-ternary phase diagrams comprising oleoyl-macrogol glycerides, water, and a surfactant/co-surfactant (S/CoS) mixture of lecithin, ethanol, and either coco glucoside or decyl glucoside were investigated for their potential to develop promising 5-FU emulsions. Six systems were selected and subjected to thermodynamic stability tests; heat-cool cycles, centrifugation, and finally freeze-thaw cycles. All systems passed the challenges and were characterized for transmission electron microscopy, droplet size, rheological behavior, pH, and transdermal permeation through newly born mice skin in Franz diffusion cells. The systems had spherical droplets ranging in diameter from 1.81 to 2.97 μm, pH values ranging from 7.50 to 8.49 and possessed Newtonian flow. A significant (P<0.05) increase in 5-FU permeability parameters as steady-state flux, permeability coefficient was achieved with formula B5 comprising water (5% w/w), S/CoS mixture of lecithin/ethanol/decyl glucoside (14.67:12.15:18.18% w/w, respectively) and oleoyl-macrogol glycerides (50% w/w). When applied to shaved rat skin, this system was well tolerated with only moderate skin irritation that was recovered within 12 h. Indeed, minor histopathologic changes were observed after 5-day treatment. Further studies should be carried out, in the future, to investigate the potentiality of this promising system to promote transdermal delivery of 5-FU through human skin. PMID:21152999

  9. Perfluorinated Alcohols Induce Complex Coacervation in Mixed Surfactants.

    PubMed

    Jenkins, Samuel I; Collins, Christopher M; Khaledi, Morteza G

    2016-03-15

    Recently, we reported a unique and nearly ubiquitous phenomenon of inducing simple and complex coacervation in solutions of a broad variety of individual and mixed amphiphiles and over a wide range of concentrations and mole fractions. This paper describes a novel type of biphasic separation in aqueous solutions of mixed cationic-anionic (catanionic) surfactants induced by hexafluoroisopropanol (HFIP). The test cases included mixtures of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) (surfactants with different carbon chain lengths) as well as dodecyltrimethylammonium bromide (DTAB) with SDS (surfactants with the same carbon chain lengths). The CTAB-SDS-HFIP coacervate systems can be produced at many different mole ratios of surfactant, but DTAB-SDS-HFIP formed only coacervates at equimolar (1:1) mole ratios of DTAB and SDS. The phase-transition behavior of both systems was studied over a wide range of surfactant and HFIP concentrations at the stoichiometric (1:1) mole ratio of cationic/anionic surfactants. The chemical compositions of each of the two phases (aqueous-rich and coacervate phases) were studied with regard to the concentrations of HFIP, water, and individual surfactants. It is revealed that the surfactant-rich phase (coacervate phase) contains a large percentage of fluoroalcohol relative to the aqueous phase and is enriched in both surfactants but contains a small percentage of water. Surprisingly, the concentration of water in the coacervate phase increases as the total HFIP concentration is increased while the concentration of HFIP in the coacervate phase remains relatively constant, which means a larger amount of water associated with HFIP molecules is extracted into the coacervate phase, which results in the growth of the phase. The volume of the coacervate phase increases with an increase in surfactant concentration and total HFIP %. The coacervate phase is highly enriched in the two amphiphilic ions (DTA(+) and DS(-)) whereas the two counterions (Br(-) and Na(+)) primarily reside in the aqueous-rich phase. The results suggest the formation of a catanionic complex in the coacervate phase through ion pairing with a concomitant release of the surfactant counterions (Na(+) and Br(-)) into the aqueous-rich phase. Finally, the fluorocarbon alcohol systems are contrasted with the effects of aliphatic alcohols in the mixed catanionic surfactant systems. Isopropanol does not have the same interactions as HFIP with respect to solubilization, aggregation, and phase separation of the oppositely charged surfactants. PMID:26881998

  10. Impact of acoustic cavitation on food emulsions.

    PubMed

    Krasulya, Olga; Bogush, Vladimir; Trishina, Victoria; Potoroko, Irina; Khmelev, Sergey; Sivashanmugam, Palani; Anandan, Sambandam

    2016-05-01

    The work explores the experimental and theoretical aspects of emulsification capability of ultrasound to deliver stable emulsions of sunflower oil in water and meat sausages. In order to determine optimal parameters for direct ultrasonic emulsification of food emulsions, a model was developed based on the stability of emulsion droplets in acoustic cavitation field. The study is further extended to investigate the ultrasound induced changes to the inherent properties of raw materials under the experimental conditions of sono-emulsification. PMID:26603612

  11. Surfactant studies for coal liquefaction

    SciTech Connect

    Hsu, G.C.

    1990-12-20

    Objectives of this project include: select economical/practical surfactants for use in coal liquefaction; screen surfactants for the proposed work through simple laboratory screening tests; and check the survivability of the selected surfactants at 350{degrees}C and 2000 psi using a 1-hour residence time for the thermal treatment in a stirred autoclave. Surfactant screening studies have shown the lignin sulfonate salt being the best candidate studied. Based upon the findings from the screening studies and practical considerations (e.g., potential cost, thermal survivability and recycling recovery), two surfactant choices in the anionic and nonionic categories were tested further in the autoclave reactor and engineering experiments at JPL. The goal of the autoclave work was to engineering experiments at JPL. The goal of the autoclave work was to determine the effects of surfactants on coal liquefaction performance and to test surfactant survivability. A eight of (8) autoclave experiments using 100 grams of as-received coal were performed. Two commercial surfactant choices were evaluated. They were: Sodium Lignin Sulfonate (LS) as a colloidal (heterogenous) surfactant of anionic type; and Triton X-100 (TRI) (trade name of a polyoxyethylated tert-octyphenol) as a liquid (homogenous) surfactant of nonionic type. Two additional reference tests were performed. 10 refs., 15 figs., 7 tabs.

  12. Determination of optimal dead sea salt content in a cosmetic emulsion using rheology and stability measurements.

    PubMed

    Abu-Jdayil, Basim; Mohameed, Hazim A; Bsoul, Abeer

    2008-01-01

    Dead Sea mud and salts are known for their therapeutic and cosmetic properties. The presence of Dead Sea (DS) salts in different types of cosmetics has affected the stability and the flow properties of the finished products. In this study, an attempt was made to find the optimum Dead Sea salt content in a cosmetic emulsion (model of body cream) using both rheology and stability measurements. The rheological properties were tested during a four-month storage period at three different storage temperatures: 8 degrees C, room temperature, and 45 degrees C. In addition to rheological measurements and centrifuge tests, the conductivities of the emulsion samples were also determined. The centrifuge tests showed that the cream samples containing more than 0.25 wt% of DS salt showed phase separation. The addition of DS salt to the cosmetic emulsion led to two maxima in the emulsion viscosity at salt contents of 0.07 wt% and 0.15 wt%. However, the emulsion samples containing 0.15% of DS salt was considered the optimum sample since it contained the maximum amount of salt and exhibited the maximum viscosity at all tested conditions. It was found that the viscosity of the emulsion is increased with storage time and storage temperature. This behavior was accompanied by a decrease in conductivity. This behavior was explained by water evaporation from the emulsion. However, it has been shown that the presence of DS salt in the cosmetic emulsion significantly reduces the rate of water evaporation. The conductivity measurements reflect the rate of water evaporation, and the presence of DS salt reduces the rate of conductivity. Conductivity is observed to decrease with storage time and temperature. PMID:18350231

  13. Analysis of improved Lattice Boltzmann phase field method for soluble surfactants

    NASA Astrophysics Data System (ADS)

    van der Sman, R. G. M.; Meinders, M. B. J.

    2016-02-01

    In this paper we present a novel Lattice Boltzmann model for immiscible fluids with soluble surfactants adsorbing at the interface with improved numerical and extended physical properties. The numerical improvements are based on the use of an analytical representation of a regularized delta-function in the surface free energy functional for the surfactant. Furthermore, the physics of the system have been extended to differential solubility of the surfactant combined with the use of Frumkin sorption behaviour. This enables the scheme to approach more realistic systems like foams and emulsions. This novel scheme is much superior in numerical stability than our previous scheme, based on a squared gradient approximation. Furthermore, we have observed the phenomenon of interface broadening under certain conditions. This phenomenon limits the surface pressure to about 30% of the capillary pressure of a bare droplet. It remains to be investigated whether this interface broadening reflects some physical effect, as has been observed for proteins.

  14. A Computational Study of the Rheology and Structure of Surfactant Covered Droplets

    NASA Astrophysics Data System (ADS)

    Maia, Joao; Boromand, Arman

    Using different types of surface-active agents are ubiquitous in different industrial applications ranging from cosmetic and food industries to polymeric nano-composite and blends. This allows to produce stable multiphasic systems like foams and emulsions whose stability and shelf-life are directly determined by the efficiency and the type of the surfactant molecules. Moreover, presence and self-assembly of these species on an interface will display complex dynamics and structural evolution under different processing conditions. Analogous to bulk rheology of complex systems, surfactant covered interfaces will response to an external mechanical forces or deformation differently depends on the molecular configuration and topology of the system constituents. Although the effect of molecular configuration of the surface-active molecules on the planar interfaces has been studied both experimentally and computationally, it remains challenging from both experimental and computational aspects to track efficiency and effectiveness of different surfactant molecules with different molecular geometries on curved interfaces. Using Dissipative Particle Dynamics, we have studies effectiveness and efficiency of different surfactant molecules on a curved interface in equilibrium and far from equilibrium. Interfacial tension is calculated for linear and branched surfactant with different hydrophobic and hydrophilic tail and head groups with different branching densities. Deformation parameter and Taylor plots are obtained for individual surfactant molecules under shear flow.

  15. 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

    2014-01-01

    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

  16. Competition between surfactant micellization and complexation by cyclodextrin.

    PubMed

    Cepeda, M; Daviña, R; García-Río, L; Parajó, M; Rodríguez-Dafonte, P; Pessêgo, M

    2013-02-21

    Supramolecular property systems composed of alkyltrimethylammonium surfactants and β-cyclodextrin were studied by means of a chemical probe. Solvolysis of 4-methoxybenzenesulfonyl chloride (MBSC) was used in the mixed systems with the aim of being able to determine the concentration of uncomplexed cyclodextrin in equilibrium with the micellar system. The surfactants used enabled us to vary the length of the hydrocarbon chain between 6 and 18 carbon atoms. In all cases the existence of a significant concentration of uncomplexed CD was observable in equilibrium with the micellar system. The percentage of uncomplexed cyclodextrin increases both on increasing and decreasing the surfactant alkyl chain length, being minimal for alkyl chains between 10-12 carbon atoms. This behavior is a consequence of two simultaneous processes: complexation of surfactant monomers by the cyclodextrin and surfactant self-assembly to form micellar aggregates. By using Gibbs free energies for micellization and surfactant complexation by β-CD, we can quantitatively explain the observed behavior. PMID:23174853

  17. Active Emulsions: Synchronization of Chemical Oscillators

    NASA Astrophysics Data System (ADS)

    Fraden, Seth

    2012-02-01

    We explore the dynamical behavior of emulsions consisting of nanoliter volume droplets of the oscillatory Belousov-Zhabotinsky (BZ) reaction separated by a continuous oil phase. Some of the aqueous BZ reactants partition into the oil leading to chemical coupling of the drops. We use microfluidics to vary the size, composition and topology of the drops in 1D and 2D. Addition of a light sensitive catalyst to the drops and illumination with a computer projector allows each drop to be individually perturbed. A variety of synchronous regimes are found that systematically vary with the coupling strength and whether coupling is dominated by activatory or inhibitory species. In 1D we observe in- and anti-phase oscillations, stationary Turing patterns in which drops stop oscillating, but form spatially periodic patterns of drops in the oxidized and reduced states, and more complex combinations of stationary and oscillatory drops. In 2D, the attractors are more complex and vary with network topology and coupling strength. For hexagonal lattices as a function of increasing coupling strength we observe right and left handed rotating oscillations, mixed oscillatory and Turing states and finally full Turing states. Reaction -- diffusion models based on a simplified description of the BZ chemistry and diffusion of messenger species reproduce a number of the experimental results. For a range of parameters, a simplified phase oscillator model provides an intuitive understanding of the complex synchronization patterns. [4pt] ``Coupled oscillations in a 1D emulsion of Belousov--Zhabotinsky droplets,'' Jorge Delgado, Ning Li, Marcin Leda, Hector O. Gonzalez-Ochoa, Seth Fraden and Irving R. Epstein, Soft Matter, 7, 3155 (2011).

  18. Polymer-surfactant complexes for microencapsulation of vitamin E and its release.

    PubMed

    Sharipova, A A; Aidarova, S B; Grigoriev, D; Mutalieva, B; Madibekova, G; Tleuova, A; Miller, R

    2016-01-01

    Microencapsulation of vitamin E directly from oil-in-water (o/w) emulsions was carried out by means of a novel practically relevant approach. For the first time, a preformed polyelectrolyte-surfactant complex (sodium polystyrene sulfonate/dodecyl trimethyl ammonium bromide) was simultaneously used as an electrosteric emulsion stabilizer and as a charged precursor for the following build up of microcapsules. Subsequently, a layer-by-layer technique was applied to emulsions leading to the formation of core-shell microcapsules with oily cores and polyelectrolyte shells. The effect of the complexes on the process of emulsion formation and on the stability and characteristics of the resulting emulsions was investigated by measurements of dynamic and equilibrium interfacial tension, size distribution (DLS) and interfacial charge (zeta-potential). The resulting microcapsules were characterized by confocal laser scanning microscopy (CLSM), Cryo-SEM, size distribution and zeta-potential measurements on each stage of the shell assembly. The release kinetics of vitamin E was monitored during the consecutive steps of the encapsulation procedure using UV-vis spectroscopy and showed the progressive enhancement of sustainability. The developed approach may be promising for the practical use in the cosmetic and food industry. PMID:25891520

  19. Adsorption of surfactants and polymers at interfaces

    NASA Astrophysics Data System (ADS)

    Rojas, Orlando Jose

    Surface tension and high-resolution laser light scattering experiments were used to investigate the adsorption of isomeric sugar-based surfactants at the air/liquid interface in terms of surfactant surface packing and rheology. Soluble monolayers of submicellar surfactant solutions exhibited a relatively viscous behavior. It was also proved that light scattering of high-frequency thermally-induced capillary waves can be utilized to study surfactant exchange between the surface and the bulk solution. Such analysis revealed the existence of a diffusional relaxation mechanism. A procedure based on XPS was developed for quantification, on an absolute basis, of polymer adsorption on mica and Langmuir-Blodgett cellulose films. The adsorption of cationic polyelectrolytes on negatively-charged solid surfaces was highly dependent on the polymer ionicity. It was found that the adsorption process is driven by electrostatic mechanisms. Charge overcompensation (or charge reversal) of mica occurred after adsorption of polyelectrolytes of ca. 50% charge density, or higher. It was demonstrated that low-charge-density polyelectrolytes adsorb on solid surfaces with an extended configuration dominated by loops and tails. In this case the extent of adsorption is limited by steric constraints. The conformation of the polyelectrolyte in the adsorbed layer is dramatically affected by the presence of salts or surfactants in aqueous solution. The phenomena which occur upon increasing the ionic strength are consistent with the screening of the electrostatic attraction between polyelectrolyte segments and solid surface. This situation leads to polyelectrolyte desorption accompanied by both an increase in the layer thickness and the range of the steric force. Adsorbed polyelectrolytes and oppositely charged surfactants readily associate at the solid/liquid interface. Such association induces polyelectrolyte desorption at a surfactant concentration which depends on the polyelectrolyte charge density. In practical systems the adsorption phenomena were found to be far more complex. Electrostatic and hydrogen bonding interactions play a major role in the adsorption of cationic polyelectrolytes on cellulosic substrates. Cationic and underivatized guar gum macromolecules form complexes with fines and dissolved and colloidal carbohydrates which are then retained on the cellulose fibers. The extent of the adsorption and association depends on the charge and nature of all the components present in pulp suspensions.

  20. Atomistic Simulations of Poly(N-isopropylacrylamide) Surfactants in Water

    NASA Astrophysics Data System (ADS)

    Abbott, Lauren J.; Stevens, Mark J.

    2015-03-01

    The amphiphilic polymer poly(N-isopropylacrylamide) (PNIPAM) displays a sharp phase transition at its LCST around 32 °C, which results from competing interactions of the hydrophobic and hydrophilic groups with water. This thermoresponsive behavior can be exploited in more complex architectures, such as block copolymers or surfactants, to provide responsive PNIPAM head groups. In these systems, however, changes to the hydrophobic/hydrophilic balance can alter the transition behavior. In this work, we perform atomistic simulations of PNIPAM-alkyl surfactants to study the temperature dependence of their structures. A single chain of the surfactant does not show temperature-responsive behavior. Instead, below and above the LCST of PNIPAM, the surfactant folds to bring the hydrophobic alkyl tail in contact with the PNIPAM backbone, shielding it from water. In addition to single chains, we explore the self-assembly of multiple surfactants into micelles and how the temperature-dependent behavior is changed. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  1. Avalanches of Rearrangements in 2D Emulsion Hopper Flow

    NASA Astrophysics Data System (ADS)

    Hong, Xia; Desmond, Kenneth; Chen, Dandan; Weeks, Eric; Weeks'lab at Emory University Team

    2014-03-01

    We conduct experiments with a quasi-two-dimensional binary emulsion flowing through a hopper. Our samples are oil-in-water emulsions confined between two close-spaced parallel plates, so that the droplets are deformed into pancake shapes. In this system, there is only viscous friction and no static friction between droplets. By imaging the droplets during flow, we observed T1 events, which are topological rearrangement events when droplets exchange neighbors. Avalanche like flow behavior has been found by controlling the flow velocity and area fraction. We study the statistics of rearrangements as a function of the control parameters and observe a fairly smooth transition from avalanche-dominated flow to continuous flow.

  2. 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.

  3. 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

  4. Nanocomposite foams from iron oxide stabilized dicyclopentadiene high internal phase emulsions: preparation and bromination.

    PubMed

    Kovačič, Sebastijan; Matsko, Nadejda B; Ferk, Gregor; Slugovc, Christian

    2014-01-01

    Nanocomposite polyHIPE foams with open-cellular morphology were obtained using nanoparticles (γFe2O3/Fe3O4), surfactant (Pluronic L121) or nanoparticle/surfactant stabilized dicyclopentadiene high internal phase emulsions (DCPD HIPEs). Upon curing, cavity sizes were found to vary drastically between 950 ± 360 µm down to 7 ±3 µm depending on the HIPE formulations. As-obtained nanocomposite polyHIPE foams were functionalized using elemental bromine in THF. Upon bromination the nanoparticles are moved from the cavities surfaces into the bulk phase of the polymer scaffold, which affects the inductive-heating capability of the magnetic nanocomposite foams decreasing it by the factor of 2. PMID:24664347

  5. Low surfactant concentration enhanced waterflooding

    SciTech Connect

    Wellington, S.L.; Richardson, E.A.

    1995-12-31

    A new gradient scaled flooding test procedure indicated that oil is mobilized by the toe of the surfactant dispersion curve where the concentration is low, 1 to 10 ppm. Underoptimum, highly interfacially active blends of anionic and cationic surfactants were synthesized and formulated to take advantage of the displacement mechanism. Essentially all the initial or residual crude oil was removed from shaly sand packs using approximately 0.4 percent surfactant with less than 0.1 pore volume lag.

  6. Properties of binary surfactant systems of nonionic surfactants C12E10, C12E23, and C12E42 with a cationic gemini surfactant in aqueous solutions.

    PubMed

    Hu, Changchao; Li, Rongqiang; Yang, Hui; Wang, Jinben

    2011-04-15

    Properties of binary surfactant systems of nonionic surfactants poly(ethylene oxide) (PEO) lauryl ethers (C(12)E(10), C(12)E(23), C(12)E(42)) with a cationic gemini surfactant, butanediyl-α,ω-bis(tetradecyldimethylammonium bromide) (14-4-14), have been investigated by Steady-state Fluorescence (FL), zeta potential, Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), Cryogenic Transmission Electron Microscopy (CryoTEM), and X-ray Diffraction (XRD). Through FL measurements, critical micelle concentration (CMC) of the three binary systems for different mixing mole fractions is determined and the values fall between those of pure constituent surfactants. Ideal CMC (CMC(ideal)), mole fraction in aggregates (X), interaction parameter (β), activity coefficients (f(1) and f(2)), and excess free energy of mixing (ΔG(ex)) have been calculated. All these parameters indicate nonideal behavior and synergistic interactions between the constituent surfactants, which is explained in terms of electrostatic attraction between headgroups of constituent surfactants and reduction of electrostatic repulsion between headgroups of 14-4-14 due to the presence of nonionic surfactants. DLS, TEM and CryoTEM results show that nonionic surfactants facilitate the formation of larger aggregates. Micelles and vesicles in larger size compared with those of 14-4-14 coexist in the mixed solutions. Both surfactant composition and PEO chain length are found to play a strong effect on the properties of the binary systems. PMID:21316703

  7. Spectroscopic investigation of the binding interactions of a membrane potential molecule in various supramolecular confined environments: contrasting behavior of surfactant molecules in relocation or release of the probe between nanocarriers and DNA surface.

    PubMed

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

    2014-12-01

    The fluorescence and optical properties of membrane potential probes are widely used to measure cellular transmembrane potentials. Hemicyanine dyes are also able to bind to membranes. The spectral properties of these molecules depend upon the charge shift from the donor moiety to the acceptor moiety. Changes in their spectral properties, i.e. absorption and emission maxima or intensities, are helpful in characterizing model membranes, microheterogeneous media, etc. In this article, we have demonstrated the binding interaction of a membrane potential probe, 1-ethyl-2-(4-(p-dimethylaminophenyl)-1,3-butadienyl)-pyridinium perchlorate (LDS 698), with various supramolecular confined environments. The larger dipole moment in the ground state compared to the excited state is a unique feature of hemicyanine dyes. Due to this unique feature, red shifts in the absorption maxima are observed in hydrophobic environments, compared with bulk solvent. On addition of surfactants and CT DNA to an aqueous solution containing LDS 698, significant increase in the emission intensity along with the quantum yield and lifetime indicate partition of the probe molecules into organized assemblies. In the case of the sodium dodecyl sulfate (SDS)-water system, due to interactions between the cationic LDS 698 and the anionic dodecyl sulfate moiety, the fluorescence intensity at ∼666 nm decreases and an additional peak at ∼590 nm appears at premicellar concentration (∼0.20 mM-4.50 mM). But at ∼5.50 mM SDS concentration, the absorbance in the higher wavelength region increases again, indicating encapsulation of the probe in micellar aggregates. This observation indicates that the premicellar aggregation behavior of SDS can also be judged by observing the changes in the UV-vis and fluorescence spectral patterns. The temperature dependent study also indicates that non-radiative deactivation of the dye molecules is highly restricted in the DNA micro-environment, compared with micelles. Besides, we have also investigated the specific interaction of surfactant micelles with DNA. Our observations reveal that, in the presence of CT DNA, LDS 698 interacts exclusively with SDS micelles, but that it preferentially releases from micelles and relocates to DNA surfaces in solutions containing TX-100 micelles. PMID:25327647

  8. Structured films of magnetizable surfactants

    NASA Astrophysics Data System (ADS)

    Taktarov, N. G.

    1982-12-01

    Qualitative results are presented of an experimental study of surfactants obtained by the deposition of small amount of ferrofluid to the surface of a nonmagnetic fluid. It is shown that the film of magnetic surfactant can be mainly in one of three states of aggregation: gaseous, liquid, or solid. Spontaneous crimping of solid surfactant films is observed in the absence of an external magnetic field, a phenomenon explained by the interaction of linear clusters perpendicular to the edge of the film. The properties of magnetic surfactant films are analogous to those of thin ferromagnetic films on a solid substrate.

  9. Host defence capacities of pulmonary surfactant: evidence for 'non-surfactant' functions of the surfactant system.

    PubMed

    Pison, U; Max, M; Neuendank, A; Weissbach, S; Pietschmann, S

    1994-09-01

    The most well characterized function of pulmonary surfactant is its ability to reduce surface tension at the alveolar air-liquid interface, thereby preventing lung collapse. However, several lines of evidence suggest that surfactant may also have 'non-surfactant' functions: specific components of surfactant (proteins and phospholipids) may interact with different alveolar cells, inhaled particles and micro-organisms modulating pulmonary host defence systems. SP-A, the most abundant surfactant protein, binds to alveolar macrophages via a specific surface receptor with high affinity [128]. Such binding effects the release of reactive oxygen species from resident alveolar macrophages if SP-A is properly presented to the target cell. SP-A also stimulates chemotaxis of alveolar macrophages [142], and serves as an opsonin in the phagocytosis of herpes simplex virus [161] Candida tropicalis [138] and various bacteria [137]. In addition, SP-A enhances the uptake of particles by monocytes and culture-derived macrophages [140] and improves bacterial killing. SP-D, another hydrophobic surfactant-associated protein, might interact with alveolar macrophages as well, stimulating the release of oxygen radicals [148], while for the hydrophilic surfactant proteins SP-B and SP-C no macrophage interactions have been described so far. SP-A and SP-D are members of the so-called 'collectins', pattern recognition molecules involved in first line defence. While some surfactant proteins appear to stimulate certain macrophage defence functions, surfactant phospholipids seem to inhibit those of lymphocytes. Suppressed lymphocyte functions include lymphoproliferation in response to mitogens and alloantigens, B cell immunoglobulin production and natural killer cell cytotoxicity. Concerning surfactant's phospholipid composition phosphatidylglycerol is more suppressive than phosphatidylcholine on a molar basis [38]. Bovine surfactant has an immunosuppressive effect on the development of hypersensitivity pneumonitis in a guinea pig model [150]. Despite these interesting observations, several important questions concerning the interactions of surfactant components with pulmonary host defence systems remain unanswered. Sufficient host defence in the lungs works through various humoral-cellular systems in conjunction with the specific anatomy of the airways and the gas exchange surface--how does the surfactant system fit into this network? Surfactant and alveolar cells are both altered during lung injury--is there a relationship between alveolar cells from RDS patients and the endogenous surfactant isolated from such patients? How does exogenous surfactant as used for substitution therapy modulate the defence system of the host? Some of those artificial surfactants have been shown to inhibit the endotoxin-alveolar macrophages, PMNs and monocytes including IL-1, IL-6 and TNF [139,152].(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7828630

  10. Hollow colloidal particles by emulsion templating, from synthesis to self-assembly

    NASA Astrophysics Data System (ADS)

    Zoldesi, C. I.

    2006-09-01

    This research was focused on developing a new method to prepare hollow colloidal particles in the micrometer range, based on emulsion templating, characterization of both the templates and the resulting particles from physical and chemical viewpoint, and fabrication of materials based on such particles. We obtained a new type of hollow colloidal particles with an elastically deformable shell which allows one to assemble them into foam-like materials and ordered crystalline arrays. For the preparation of hollow particles, we used an emulsion templating technique in which monodisperse silicone oil-in-water emulsion droplets, surfactant free, were used as templates for the encapsulation with solid shells consisting of a silica/siloxane copolymer. This method opens the possibility of preparing different types of hollow particles with tunable sizes and interesting properties. We also investigated the possibility of using surfactant-stabilized emulsion droplets as templates for the encapsulation with solid shells. Both the emulsion droplets used as templates and the resulting hollow shells were investigated with a variety of techniques. The size and polydispersity of the oil droplets and the thickness of the coating were determined from Static Light Scattering. Solution 29Si NMR and solid state 29Si NMR were used to obtain information about the silicon atoms bonded to different groups present in the silicone oil emulsions and in the shell material of hollow spheres, respectively. Additionally, Energy Dispersive X-rays (EDX) was used to determine the elemental composition of the shell material. Special emphasis was put on the elastic properties of the hollow shells which were measured the by Scanning Force Microscopy (SFM) nanoindentation. We demonstrated by confocal laser scanning microscopy that the shells are permeable to small molecules and that fluorescent dye molecules can be incorporated into the shell material. The morphology of the hollow shells was investigated with Transmission Electron Microscopy (TEM). We showed that the particles' deformability makes it possible to prepare new types of regularly deformed particles, bubble-like clusters and solid microcellular foams. Additionally, the hollow particles can be incorporated as defects in crystals of silica spheres.

  11. Solution and interfacial behavior of modified silicone polymers and their interactions with solid substrates

    NASA Astrophysics Data System (ADS)

    Purohit, Parag

    Surface treatment is very important step in many applications such as fabric finishing, coatings, cosmetics and personal care. Silicone polymers are a class of organic/inorganic materials that show unique properties such as weak intermolecular forces and high flexibility enabling even a very high molecular weight chain to achieve optimal orientation on surfaces. Material properties such as softness, repellency, bounciness and friction can therefore be tailored by using appropriately modified silicone polymers. Despite wide applications, the underlying mechanisms of material modification are unknown and tailoring silicones for applications remains mostly empirical. Thus the objective of this research is to understand the solution and interfacial behavior of functionalized silicone polymers, which govern their performance in material modification. Modified silicones are simultaneously hydrophobic and oleophobic in nature and due to this nearly universal non-compatibility, the studies of these polymers present unusual challenges. Due to this incompatible nature, the functionalized silicone polymers were emulsified into O/W emulsions to study their solution and interfacial properties. The colloidal properties such as electrokinetic and droplet distribution of these emulsions are assumed to play an important role in the observed surface and physical properties of solid substrates (in present study, cellulosic substrates) as well the stability of emulsions itself. To understand the effects of modified silicones on cellulosic substrates a variety of techniques such as frictional analysis, scanning electron microscopy and atomic force microscopy that can probe from macro to nano level were used. It is hypothesized that the size distribution and charge of silicone emulsions as well as the physiochemical conditions such as pH, control silicone conformation which in turn affect the modification of the substrate properties. With bimodal droplet distribution of silicone emulsions, the nano-sized droplets can penetrate deeper into the substrate to provide bounciness, whereas macro-sized droplets can coat the top layer leading to friction reduction. It was observed that at pH 5.5 the silicone treatment resulted in charge reversal of fibers as opposed to treatment at pH 9.5. On a macroscopic scale 20% reduction in frictional coefficient of the fabric was observed after treatment with quaternized (cationically modified) silicones as compared to untreated fibers. It was also observed using AFM that the fibrils treated with quaternized silicones are uniform, well stacked and smoother than the untreated fibers. Spectroscopic analysis of treated fibers using Raman spectroscopy indicated a decrease in fiber stress as a function of modification of silicone polymer and the interaction pH. It is concluded that the protonated amine functional silicone (below pH 7) as well as the quaternized silicone interacts with the negatively charged cellulose fibers primarily through electrostatic interactions. It is proposed that this initial surface coating is a uniform thin film which allows further deposition of polymer from the emulsion. It was observed that at high pH the zetapotential of silicone emulsions decreases drastically and the nano emulsions turn turbid. It is proposed that the observed electrophoretic and nephelometric behavior at high pH is due to flocculation of nanosized droplets to micron size, which eventually leads to droplets coalescing and emulsion destabilization. It is also postulated that the nano emulsion possess a critical dilution concentration (CDC), above which dilution leads to rapid coalescence. This critical dilution phase was further confirmed through polarity parameter and excimer formation studies which show significantly different polymer and surfactant microstructures near the CDC. Hence it is concluded that the observed surface properties of the substrate obtained above the CDC are significantly different than those below the CDC. The results reveal the vital role of physiochemical parameters such as pH, droplet size, and concentration on the emulsion stability as well as the observed physical/chemical properties of the substrates.

  12. Development of low-energy methods for preparing food Nano-emulsions.

    PubMed

    Miyanoshita, Michitaka; Hashida, Chitose; Ikeda, Shinya; Gohtani, Shoichi

    2011-01-01

    The aim of this work was to investigate the effect of sucrose on the phase behavior of vegetable oil/polyoxyethylene sorbitan monooleate (MOPS, Tween 80) and decaglycerol monolaurilester (DGML)/aqueous solution systems to establish low-energy emulsification methods for preparing nano-emulsions suitable for food uses. Phase diagrams were constructed to elucidate the optimal process for preparing the nano-emulsions. It was found that nano-emulsions were obtained when the composition was altered to either cross the sponge phase (L(3)) or lamellar phase (La) in the vegetable oil/MOPS/aqueous solution system or vegetable oil/DGML/aqueous solution system, respectively. The average droplet sizes in the former and latter emulsions were 0.203 µm and 0.165 µm, respectively. The addition of sucrose changed the hexagonal phase in the vegetable oil/MOPS/aqueous solution system into the sponge phase. As a result, the sponge region in the vegetable oil/MOPS/sucrose aqueous solution system occupied a larger area than that in the vegetable oil/MOPS/water system. In contrast, sucrose had no effect on the area of the La region in the vegetable oil/DGML/aqueous solution system. However, the addition of sucrose decreased the amount of emulsifier required to prepare nano-emulsions in both the vegetable oil/MOPS and DGML/aqueous solution systems. Sucrose was confirmed to facilitate the preparation of nano-emulsions in both systems. PMID:21701099

  13. Particle condition change in emulsion admixture evaluated by in situ flow particle imaging analysis.

    PubMed

    Ohkawa, Tomoyo; Uchino, Tomonobu; Sasakura, Daisuke; Miyazaki, Yasunori; Kagawa, Yoshiyuki

    2013-01-01

    We evaluated the particle state change in emulsion admixtures using in situ flow particle imaging analysis (FPIA). Ropion® intravenous (flurbiprofen axetil: Ropion®) served as the model emulsion formulation. A binary mixture of Ropion® and normal saline (NS), and a ternary admixture of Ropion®, NS, and Gaster® injection (famotidine: Gaster®) or Primperan® injection (metoclopramide hydrochloride: Primperan®) were prepared and the change in emulsion particle state was analyzed using FPIA under in situ condition. The effect of storage on pH change and the chemical stability of flurbiprofen axetil were also investigated. In Ropion®, various particle images (mean diameter: 2.4 µm) were obtained. From our analysis of changes in scattergrams and particle images, changing behaviors of emulsion particles as a function of storage time depended on the systems of admixture samples. In Ropion®/NS and Ropion®/Gaster®/NS systems, mean particle size and particle number increased with lengthening storage time; however, these values were dramatically increased beyond 6 h in the Ropion®/Primperan®/NS system, corresponding to a decrease in measured pH. The decomposition of flurbiprofen axetil due to incompatibility was not observed in all systems. Detailed information on the change in emulsion particle state was obtained using FPIA, indicating that this method is useful to evaluate state changes in emulsion admixtures under in situ condition. PMID:23449203

  14. 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.

  15. 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.

  16. Suppression of Ostwald ripening in active emulsions.

    PubMed

    Zwicker, David; Hyman, Anthony A; Jülicher, Frank

    2015-07-01

    Emulsions consisting of droplets immersed in a fluid are typically unstable since they coarsen over time. One important coarsening process is Ostwald ripening, which is driven by the surface tension of the droplets. Stability of emulsions is relevant not only in complex fluids but also in biological cells, which contain liquidlike compartments, e.g., germ granules, Cajal bodies, and centrosomes. Such cellular systems are driven away from equilibrium, e.g., by chemical reactions, and thus can be called active emulsions. In this paper, we study such active emulsions by developing a coarse-grained description of the droplet dynamics, which we analyze for two different chemical reaction schemes. We first consider the simple case of first-order reactions, which leads to stable, monodisperse emulsions in which Ostwald ripening is suppressed within a range of chemical reaction rates. We then consider autocatalytic droplets, which catalyze the production of their own droplet material. Spontaneous nucleation of autocatalytic droplets is strongly suppressed and their emulsions are typically unstable. We show that autocatalytic droplets can be nucleated reliably and their emulsions stabilized by the help of chemically active cores, which catalyze the production of droplet material. In summary, different reaction schemes and catalytic cores can be used to stabilize emulsions and to control their properties. PMID:26274171

  17. Suppression of Ostwald ripening in active emulsions

    NASA Astrophysics Data System (ADS)

    Zwicker, David; Hyman, Anthony A.; Jülicher, Frank

    2015-07-01

    Emulsions consisting of droplets immersed in a fluid are typically unstable since they coarsen over time. One important coarsening process is Ostwald ripening, which is driven by the surface tension of the droplets. Stability of emulsions is relevant not only in complex fluids but also in biological cells, which contain liquidlike compartments, e.g., germ granules, Cajal bodies, and centrosomes. Such cellular systems are driven away from equilibrium, e.g., by chemical reactions, and thus can be called active emulsions. In this paper, we study such active emulsions by developing a coarse-grained description of the droplet dynamics, which we analyze for two different chemical reaction schemes. We first consider the simple case of first-order reactions, which leads to stable, monodisperse emulsions in which Ostwald ripening is suppressed within a range of chemical reaction rates. We then consider autocatalytic droplets, which catalyze the production of their own droplet material. Spontaneous nucleation of autocatalytic droplets is strongly suppressed and their emulsions are typically unstable. We show that autocatalytic droplets can be nucleated reliably and their emulsions stabilized by the help of chemically active cores, which catalyze the production of droplet material. In summary, different reaction schemes and catalytic cores can be used to stabilize emulsions and to control their properties.

  18. Kinetics of crosslinking in emulsion polymerization

    SciTech Connect

    Ghielmi, A.; Fiorentino, S.; Morbidelli, M.

    1996-12-31

    A mathematical model for evaluating the chain length distribution of nonlinear polymers produced in emulsions is presented. The heterogeneous emulsion polymerization process is described. The aim of the analysis is the distribution of active polymer chains and pairs of chains with a given growth time in latex particles in state.

  19. Metallic nanoshells on porphyrin-stabilized emulsions

    DOEpatents

    Wang, Haorong; Song, Yujiang; Shelnutt, John A; Medforth, Craig J

    2013-10-29

    Metal nanostructures formed by photocatalytic interfacial synthesis using a porphyrin-stabilized emulsion template and the method for making the nanostructures. Catalyst-seeded emulsion droplets are employed as templates for hollow-nanoshell growth. The hollow metal nanospheres may be formed with or without inclusions of other materials.

  20. Jamming of quasi-2D emulsion droplets: Analogies with granular jamming

    NASA Astrophysics Data System (ADS)

    Weeks, Eric R.; Desmond, Kenneth W.; Young, Pearl J.; Chen, Dandan

    2012-11-01

    We experimentally study the jamming of quasi-two-dimensional emulsions. Our experiments consist of oil-in-water emulsion droplets confined between two parallel plates. These are somewhat analogous to granular photoelastic disks, although they are softer and do not experience static friction. From the droplet outlines, we can determine the forces between every droplet pair to within 8% over a wide range of area fractions. Using the data, we observe critical scaling behaviors of the contact numbers and pressure as the jamming transition is approached from above. The scaling behavior agrees well with simulations and is similar to what has been seen previously with photoelastic disks.

  1. Surfactant phosphatidylcholine metabolism and surfactant function in preterm, ventilated lambs

    SciTech Connect

    Jobe, A.H.; Ikegami, M.; Seidner, S.R.; Pettenazzo, A.; Ruffini, L.

    1989-02-01

    Preterm lambs were delivered at 138 days gestational age and ventilated for periods up to 24 h in order to study surfactant metabolism and surfactant function. The surfactant-saturated phosphatidylcholine pool in the alveolar wash was 13 +/- 4 mumol/kg and did not change from 10 min to 24 h after birth. Trace amounts of labeled natural sheep surfactant were mixed with fetal lung fluid at birth. By 24 h, 80% of the label had become lung-tissue-associated, yet there was no loss of label from phosphatidylcholine in the lungs when calculated as the sum of the lung tissue plus alveolar wash. De novo synthesized phosphatidylcholine was labeled with choline given by intravascular injection at 1 h of age. Labeled phosphatidylcholine accumulated in the lung tissue linearly to 24 h, and the labeled phosphatidylcholine moved through lamellar body to alveolar pools. The turnover time for alveolar phosphatidylcholine was estimated to be about 13 h, indicating an active metabolic pool. A less surface-active surfactant fraction recovered as a supernatant after centrifugation of the alveolar washes at 40,000 x g increased from birth to 10 min of ventilation, but no subsequent changes in the distribution of surfactant phosphatidylcholine in surfactant fractions occurred. The results were consistent with recycling pathway(s) that maintained surface-active surfactant pools in preterm ventilated lambs.

  2. Electrophoretic separations in poly(dimethylsiloxane) microchips using a mixture of ionic and zwitterionic surfactants.

    PubMed

    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 electroosmotic flow (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 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

  3. Destabilization of emulsions by natural minerals.

    PubMed

    Yuan, Songhu; Tong, Man; Wu, Gaoming

    2011-09-15

    This study developed a novel method to destabilize emulsions and recycle oils, particularly for emulsified wastewater treatment. Natural minerals were used as demulsifying agents, two kinds of emulsions collected from medical and steel industry were treated. The addition of natural minerals, including artificial zeolite, natural zeolite, diatomite, bentonite and natural soil, could effectively destabilize both emulsions at pH 1 and 60 °C. Over 90% of chemical oxygen demand (COD) can be removed after treatment. Medical emulsion can be even destabilized by artificial zeolite at ambient temperature. The mechanism for emulsion destabilization by minerals was suggested as the decreased electrostatic repulsion at low pH, the enhanced gathering of oil microdroplets at elevated temperature, and the further decreased surface potential by the addition of minerals. Both flocculation and coalescence were enhanced by the addition of minerals at low pH and elevated temperature. PMID:21784583

  4. Aging mechanism in model Pickering emulsion

    NASA Astrophysics Data System (ADS)

    Fouilloux, Sarah; Malloggi, Florent; Daillant, Jean; Thill, Antoine

    We study the stability of a model Pickering emulsion system. A special counter-flow microfluidics set-up was used to prepare monodisperse Pickering emulsions, with oil droplets in water. The wettability of the monodisperse silica nanoparticles (NPs) could be tuned by surface grafting and the surface coverage of the droplets was controlled using the microfluidics setup. A surface coverage as low as 23$\\%$ is enough to stabilize the emulsions and we evidence a new regime of Pickering emulsion stability where the surface coverage of emulsion droplets of constant size increases in time, in coexistence with a large amount of dispersed phase. Our results demonstrate that the previously observed limited coalescence regime where surface coverage tends to control the average size of the final droplets must be put in a broader perspective.

  5. Emulsion based cast booster - a priming system

    SciTech Connect

    Gupta, R.N.; Mishra, A.K.

    2005-07-01

    This paper explores the potential of emulsion based cast booster to be used as primer to initiate bulk delivered emulsion explosives used in mines. An attempt has been made for comparative study between conventional cast booster and emulsion based cast booster in terms of the initiation process developed and their capability to develop and maintain the stable detonation process in the column explosives. The study has been conducted using a continuous velocity of detonation (VOD) measuring instrument. During this study three blasts have been monitored. In each blast two holes have been selected for study, the first hole being initiated with conventional cast booster while the other one with emulsion based cast booster. The findings of the study advocates that emulsion based cast booster is capable of efficient priming of bulk delivered column explosive with stable detonation process in the column. Further, the booster had advantages over the conventional PETN/TNT based cast booster. 5 refs., 2 figs., 1 tab., 1 photo.

  6. Non-aqueous Isorefractive Pickering Emulsions.

    PubMed

    Thompson, Kate L; Lane, Jacob A; Derry, Matthew J; Armes, Steven P

    2015-04-21

    Non-aqueous Pickering emulsions of 16-240 μm diameter have been prepared using diblock copolymer worms with ethylene glycol as the droplet phase and an n-alkane as the continuous phase. Initial studies using n-dodecane resulted in stable emulsions that were significantly less turbid than conventional water-in-oil emulsions. This is attributed to the rather similar refractive indices of the latter two phases. By utilizing n-tetradecane as an alternative oil that almost precisely matches the refractive index of ethylene glycol, almost isorefractive ethylene glycol-in-n-tetradecane Pickering emulsions can be prepared. The droplet diameter and transparency of such emulsions can be systematically varied by adjusting the worm copolymer concentration. PMID:25844544

  7. Non-aqueous Isorefractive Pickering Emulsions

    PubMed Central

    2015-01-01

    Non-aqueous Pickering emulsions of 16–240 μm diameter have been prepared using diblock copolymer worms with ethylene glycol as the droplet phase and an n-alkane as the continuous phase. Initial studies using n-dodecane resulted in stable emulsions that were significantly less turbid than conventional water-in-oil emulsions. This is attributed to the rather similar refractive indices of the latter two phases. By utilizing n-tetradecane as an alternative oil that almost precisely matches the refractive index of ethylene glycol, almost isorefractive ethylene glycol-in-n-tetradecane Pickering emulsions can be prepared. The droplet diameter and transparency of such emulsions can be systematically varied by adjusting the worm copolymer concentration. PMID:25844544

  8. Solution behaviors and self-assembly of polyoxometalates as models of macroions and amphiphilic polyoxometalate-organic hybrids as novel surfactants.

    PubMed

    Yin, Panchao; Li, Dong; Liu, Tianbo

    2012-11-21

    Large, hydrophilic polyoxoanions with high solubility in water and/or other polar solvents demonstrate unique solution behavior by self-assembling into single layer, hollow, spherical "blackberry" structures, which is obviously different from small, simple ions. These macroions cannot be treated as insoluble colloidal suspensions because they form stable "real solutions". Counterion-mediated attraction is considered as the main driving force for the self-assembly behavior. The size disparity between the macroions and their counterions results in macroion-counterion pairing which leads to the inter-macroanionic attraction. The blackberries, with robust membranes semi-permeable to cations, can adjust their size accurately and reversibly in response to the change of solvent polarity and charge density of individual macroions. The inorganic macroions with well-defined size, shape, mass, charge density, but no intramolecular interactions, are ideal model systems to study the intermolecular interactions in polyelectrolyte and bio-macromolecular solutions. The blackberry structures show certain similarities to spherical viral capsids, from the overall structure to the formation kinetics. More amazingly, these inorganic macroions demonstrate some features usually believed to belong only to complex biological molecules, such as the self-recognition in dilute solutions. Meanwhile, polyoxometalates-based organic-inorganic hybrid materials demonstrate amphiphilic properties by self-assembling into vesicles and reverse vesicles in polar and non-polar solvents, respectively, and form monolayer at the water/air interface. Different from conventional amphiphiles, these hybrids show pH-dependent and counterion-dependent self-assembly behaviors with controllable functionality, e.g. fluorescence and catalytic activity, due to the high and tunable charges and the functionalities of POM polar head groups. PMID:22858584

  9. MINERAL-SURFACTANT INTERACTIONS FOR MINIMUM REAGENTS PRECIPITATION AND ADSORPTION FOR IMPROVED OIL RECOVERY

    SciTech Connect

    P. Somasundaran

    2005-04-30

    The aim of this project is to delineate the role of mineralogy of reservoir rocks in determining interactions between reservoir minerals and externally added reagents (surfactants/polymers) and its effect on critical solid-liquid and liquid-liquid interfacial properties such as adsorption, wettability and interfacial tension in systems relevant to reservoir conditions. Previous studies have suggested that significant surfactant loss by precipitation or adsorption on reservoir minerals can cause chemical schemes to be less than satisfactory for enhanced oil recovery. Both macroscopic adsorption, wettability and microscopic orientation and conformation studies for various surfactant/polymer mixtures/reservoir rocks systems were conducted to explore the cause of chemical loss by means of precipitation or adsorption, and the effect of rock mineralogy on the chemical loss. During this period, the adsorption of mixed system of n-dodecyl-{beta}-D-maltoside (DM) and dodecyl sulfonate (C{sub 12}SO{sub 3}Na) has been studied. The effects of solution pH, surfactant mixing ratio and different salts on surfactant adsorption on alumina have been investigated in detail. Along with these adsorption studies, changes in mineral wettability due to the adsorption of the mixtures were determined under relevant conditions to identify the nano-structure of the adsorbed layers. Solution properties of C{sub 12}SO{sub 3}Na/DM mixtures were also studied to identify surfactant interactions that affect the mixed aggregate formation in solution. Adsorption of SDS on gypsum and limestone suggested stronger surfactant/mineral interaction than on alumina, due to the precipitation of surfactant by dissolved calcium ions. The effects of different salts such as sodium nitrate, sodium sulfite and sodium chloride on DM adsorption on alumina have also been determined. As surfactant hemimicelles at interface and micelles in solution have drastic effects on oil recovery processes, their microstructures in solutions and at mineral/solution interfaces were investigated by monitoring micropolarity of the aggregates using fluorescence technique. Compositional changes of the aggregates in solution were observed with the increase in surfactant concentration. The importance of this lies in that the resulting polarity/hydrophobicity change of the mixed micelles will affect the adsorption of surfactant mixtures on reservoir minerals, surfactant/oil emulsion formation and wettability, as a result, the oil release efficiency of the chemical flooding processes in EOR.

  10. Self-assembly behavior of lipids at an oil-water interface

    NASA Astrophysics Data System (ADS)

    Pautot, Sophie

    The hydrophilic and hydrophobic properties of lipid molecules enable them to organize into large structures when dissolved in water or in oil. Under certain conditions and with the right they can organize into micellar or into lamellar phases under certain conditions and with the right system composition. The equilibrium phase of lipids have been well studied. In this work we observe the behavior of lipids at an oil-water interface, and we investigate the molecular assembly that can result in the presence of lipids at an oil-water interface. We have established that lipids can be used as a surfactant to stabilize water droplets in oil, and we have developed a new method, a reverse emulsion technique, that allows us to use these emulsions to assemble unilamellar vesicles with a high encapsulation yield. The vesicle bilayer is formed from the assembly of two monolayers formed independently and we have proven that this technique offers the possibility to directly assemble asymmetric bilayer. Because the encapsulated phase remains contained at all time by a surfactant layer the reactivity of the molecules initially encapsulated can be preserved. We have demonstrated using fluorescence measurement that the vesicles formed can be used as micro-reactor where reactive molecules can be encapsulated and their activity remotely triggered. This technique is not limited to lipids and we have demonstrated that the process can also be applied to other amphiphilic molecules such as polymers or synthetic surfactants. In addition, we have used dynamic light scattering to study the size of the inverted emulsion stabilized with lipids as a function of the shear applied to the suspension. We have established that a water drop injected in an alkane solution such as dodecane lead to the spontaneous formation of emulsion droplet. Moreover we have demonstrated that the spontaneous emulsification is due to the swelling of a lyotropic semi-crystalline phase which forms at the dodecane-water interface. We have observed by optical microscopy that large droplet composed of lipid and water grow at the interface and lead to the formation of onion like assembly in dodecane.

  11. Formation of wrinkled silica mesostructures based on the phase behavior of pseudoternary systems.

    PubMed

    Moon, Doo-Sik; Lee, Jin-Kyu

    2014-12-30

    Water-surfactant-oil ternary systems have various phase behaviors and substructures that depend on their chemical composition and component ratio. These substructures can be used as templates for the synthesis of a variety of nanostructures. In this study, the phase behavior of a pseudoternary system consisting of aqueous urea-cetyltrimethylammonium bromide (and n-butanol)-cyclohexane is analyzed. Additionally, wrinkled silica mesostructures (WSMs) with various morphologies are synthesized using the microemulsion layer in the multiphase areas of the pseudoternary system with restricted degrees of freedom as a template. The particle size of the wrinkled silica nanoparticles (WSNs) and the connective morphology of the WSMs can be controlled via the catalytic conditions. In addition, some materials that are difficult to produce, such as radially branched WSNs and shuttlecock-shaped Janus nanoparticles, are prepared using a gradual seed-growth mechanism of silica in the emulsion system. PMID:25454837

  12. Surfactant monitoring by foam generation

    DOEpatents

    Mullen, Ken I.

    1997-01-01

    A device for monitoring the presence or absence of active surfactant or other surface active agents in a solution or flowing stream based on the formation of foam or bubbles is presented. The device detects the formation of foam with a light beam or conductivity measurement. The height or density of the foam can be correlated to the concentration of the active surfactant present.

  13. Surfactant-assisted coal liquefaction

    NASA Technical Reports Server (NTRS)

    Hsu, G. C.

    1977-01-01

    Improved process of coal liquefaction utilizing nonaqueous surfactant has increased oil yield from 50 to about 80%. Asphaltene molecule formation of colloid particles is prevented by surfactant. Separated molecules present more surface area for hydrogenation reaction. Lower requirements for temperature, pressure, and hydrogen lead to reduction in capital and operation costs.

  14. NATURAL SURFACTANTS IN PAPER RECYCLING

    EPA Science Inventory

    The objective of this project is to introduce new types of surfactants based on renewable materials (sugar surfactants) for use in ink removal from recycled paper. By applying green chemistry approaches we not only will solve an important industry and environmental problem but...

  15. 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...

  16. Arresting relaxation in Pickering Emulsions

    NASA Astrophysics Data System (ADS)

    Atherton, Tim; Burke, Chris

    2015-03-01

    Pickering emulsions consist of droplets of one fluid dispersed in a host fluid and stabilized by colloidal particles absorbed at the fluid-fluid interface. Everyday materials such as crude oil and food products like salad dressing are examples of these materials. Particles can stabilize non spherical droplet shapes in these emulsions through the following sequence: first, an isolated droplet is deformed, e.g. by an electric field, increasing the surface area above the equilibrium value; additional particles are then adsorbed to the interface reducing the surface tension. The droplet is then allowed to relax toward a sphere. If more particles were adsorbed than can be accommodated by the surface area of the spherical ground state, relaxation of the droplet is arrested at some non-spherical shape. Because the energetic cost of removing adsorbed colloids exceeds the interfacial driving force, these configurations can remain stable over long timescales. In this presentation, we present a computational study of the ordering present in anisotropic droplets produced through the mechanism of arrested relaxation and discuss the interplay between the geometry of the droplet, the dynamical process that produced it, and the structure of the defects observed.

  17. 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.

  18. Surfactant induced autophobing.

    PubMed

    Bera, B; Duits, M H G; Cohen Stuart, M A; van den Ende, D; Mugele, F

    2016-05-18

    Surfactant adsorption in a three-phase system and its influence on wetting properties are relevant in various applications. Here, we report a hitherto not observed phenomenon, namely the retraction of an aqueous drop on hydrophilic solid substrates (which we refer to as 'autophobing') in ambient oil containing water-insoluble fatty acids, caused by the deposition of these fatty acids from the ambient oil onto the solid substrate. AFM measurements confirm that the surfactant is deposited on the solid by the moving contact line. This leads to a more hydrophobic substrate, the retraction of the contact line and a concomitant increase in the contact angle. The deposition process is enabled by the formation of a reaction product between deprotonated fatty acids and Ca(2+) ions at the oil/water interface. We investigate how the transition to a new equilibrium depends on the concentrations of the fatty acids, the aqueous solute, the chain lengths of the fatty acid, and the types of alkane solvent and silica or mica substrates. This phenomenon is observed on both substrates and for all explored combinations of fatty acids and solvents and thus appears to be generic. In order to capture the evolution of the contact angle, we develop a theoretical model in which the rate of adsorption at the oil-water interface governs the overall kinetics of autophobing, and transfer to the solid is determined by a mass flux balance (similar to a Langmuir Blodgett transfer). PMID:27102975

  19. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-10-01

    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. Alfoterra-38 (0.05 wt%), Alfoterra-35 (0.05 wt%), SS-6656 (0.05 wt%), and DTAB (1 wt%) altered the wettability of the initially oil-wet calcite plate to an intermediate/water-wet state. Low IFT ({approx}10{sup -3} dynes/cm) is obtained with surfactants 5-166, Alfoterra-33 and Alfoterra-38. Plans for the next quarter include conducting wettability and mobilization studies.

  20. A novel method for the synthesis of CdS nanoparticles without surfactant.

    PubMed

    Ghows, N; Entezari, M H

    2011-01-01

    Cadmium sulfide nanoparticles with a hexagonal phase (∼10 nm) were prepared at a relatively low temperature (70°C). This synthesis was carried out shortly (30 min) through a new micro-emulsion (O/W) induced by ultrasound without surfactant. Ultrasound can provide an excess energy for new interface formation and obtain emulsions even in the absence of surfactants. This technique avoids some problems that normally exist in conventional micro-emulsion synthesis such as the presence of different additives and calcinations. In addition, it was possible to tune the particle size, the band gap, and the phases of CdS nanoparticles by changing the variables such as ultrasonic irradiation time, intensity, precursor, and ratio of the components. It was also found that the synthesized nanoparticles have a band-edge emission at about 460 nm with a blue-shift to a higher energy which is due to the typical quantum confinement effects. The product was characterized by different techniques such as UV-visible absorption spectroscopy, X-ray powder diffraction, and high resolution transmission electron microscopy (HRTEM). PMID:20638317

  1. Theoretical and Simulations-Based Modeling of Micellization in Linear and Branched Surfactant Systems

    NASA Astrophysics Data System (ADS)

    Mendenhall, Jonathan D.

    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 surfactant concentration, including: (i) formation of surfactant monolayers at surfaces and interfaces, and (ii) self-assembly into finite aggregates (micelles) in the bulk solution beyond the critical micelle concentration (cmc). This concentration-dependent phase behavior induces changes in solution properties. For example, the surface activity of surfactants can decrease the surface tension, and self-assembly in bulk solution can lead to changes in viscosity, equivalent conductivity, solubilization capacity, and other bulk properties. These effects make surfactants quite attractive and unique for use in product formulations, where they are utilized as detergents, dispersants, emulsifiers, solubilizers, surface and interfacial tension modifiers, and in other contexts. The specific chemical structure of the surfactant head and tail is essential in determining the overall performance properties of a surfactant in aqueous media. The surfactant tail drives the self-assembly process through the hydrophobic effect, while the surfactant head imparts a certain extent of solubility to the surfactant in aqueous solution through preferential interactions with the hydrogen-bonding network of water. The interplay between these two effects gives rise to the particular phase diagram of a surfactant, including the specific cmc at which micelles begin to form. In addition to serving as a quantitative indicator of micelle formation, the cmc represents a limit to surface monolayer formation, and hence to surface and interfacial tension reduction, because surfactant adsorption at interfaces remains approximately constant beyond the cmc. In addition, the cmc represents the onset of changes in bulk solution properties. This Thesis is concerned with the prediction of cmc's and other micellization properties for a variety of linear and branched surfactant chemical architectures which are commonly encountered in practice. Single-component surfactant solutions are investigated, in order to clarify the specific contributions of the surfactant head and tail to the free energy of micellization, a quantity which determines the cmc and all other aspects of micellization. First, a molecular-thermodynamic (MT) theory is presented which makes use of bulk-phase thermodynamics and a phenomenological thought process to describe the energetics related to the formation of a micelle from its constituent surfactant monomers. Second, a combined computer-simulation/molecular-thermodynamic (CSMT) framework is discussed which provides a more detailed quantification of the hydrophobic effect using molecular dynamics simulations. A novel computational strategy to identify surfactant head and tail using an iterative dividing surface approach, along with simulated micelle results, is proposed. Force-field development for novel surfactant structures is also discussed. Third, a statistical-thermodynamic, single-chain, mean-field theory for linear and branched tail packing is formulated, which enables quantification of the specific energetic penalties related to confinement and constraint of surfactant tails within micelles. Finally, these theoretical and simulations-based strategies are used to predict the micellization behavior of 55 linear surfactants and 28 branched surfactants. Critical micelle concentration and optimal micelle properties are reported and compared with experiment, demonstrating good agreement across a range of surfactant head and tail types. In particular, the CSMT framework is found to provide improved agreement with experimental cmc's for the branched surfactants considered. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

  2. Influence of the ratio of amphiphilic copolymers used as emulsifiers on the microstructure, physical stability and rheology of α-pinene emulsions stabilized with gellan gum.

    PubMed

    García, M Carmen; Alfaro, M Carmen; Muñoz, José

    2015-11-01

    α-Pinene is a terpenic solvent whose use in the formulation of emulsions entails a double benefit from the environmental point of view since it is a green solvent, easily biodegradable, which also has certain antimicrobial properties. In this work a combination of Atlas™ G-5000 and Atlox™ 4913 amphiphilic copolymers was used to obtain O/W emulsions formulated with α-pinene and gellan gum. These emulsions may find applications related to the design of complex biotechnological systems with different uses. In order to investigate the microstructure and the physical stability of these emulsions, a combination of different techniques such as rheology, microscopy, laser diffraction and multiple light scattering turn out to be a useful methodology. The results demonstrated the need to include a minimum amount of Atlas™ G-5000 copolymer in the formulation of these emulsions to improve their stability. These results were supported by the information revealed by optical micrographs, according to which Atlas™ G-5000 is directed to the continuous medium to structure water (this surfactant is particularly effective at forming hydrogen bonds with water). On the other hand Atlox™ 4913 is preferentially adsorbed at the α-pinene-water interface, such that a high Atlox™ 4913/Atlas™ G-5000 mass ratio slows down the kinetics of coalescence as shown by multiple light scattering. However, a very low relative concentration of Atlas™ G-5000 causes creaming to become the dominant destabilization mechanism. Increasing the Atlas™ G-5000/Atlox™ 4913 mass ratio yields emulsions with enhanced viscosity and viscoelasticity. PMID:26283495

  3. Pickering emulsions stabilized by soft microgels: influence of the emulsification process on particle interfacial organization and emulsion properties.

    PubMed

    Destribats, Mathieu; Wolfs, Mélanie; Pinaud, Florent; Lapeyre, Véronique; Sellier, Elisabeth; Schmitt, Véronique; Ravaine, Valérie

    2013-10-01

    This work reports a new evidence of the versatility of soft responsive microgels as stabilizers for Pickering emulsions. The organization of microgels at the oil-water interface is a function of the preparation pathway. The present results show that emulsification energy can be used as a trigger to modify microgel deformation at the oil-water interface and their packing density: high shear rates bring strong flattening of the microgels, whereas low shear rates lead to dense monolayers, where the microgels are laterally compressed. As a consequence, the resulting emulsions have opposite behavior in terms of flocculation, which arises from bridging between neighboring drops and is strongly dependent on their surface coverage. This strategy can be applied to any microgel which can sufficiently adsorb at low shear rates, i.e. small microgels or lightly cross-linked ones. The control of the organization of microgels at the interface does not only modify emulsion end-use properties but also constitutes a new tool for the development of Janus-type microgels, obtained by chemical modification of the adsorbed microgels. PMID:24050149

  4. 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 1μm. 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.

  5. Latest Developments in Nuclear Emulsion Technology

    NASA Astrophysics Data System (ADS)

    Morishima, Kunihiro

    Nuclear emulsion is high sensitive photographic film used for detection of three-dimensional trajectory of charged particles. These trajectories are recorded as tracks consist of a lot of silver grains. The size of silver grain is about 1 μm, so that nuclear emulsion has submicron three-dimensional spatial resolution, which gives us a few mrad three-dimensional angular resolution. The important technical progress was speed-up of the read-out technique of nuclear emulsions built with optical microscope system. We succeeded in developing a high-speed three-dimensional read-out system named Super Ultra Track Selector (S-UTS) with the operating read-out speed of approximately 50 cm2/h. Nowadays we are developing the nuclear emulsion gel independently in Nagoya University by introducing emulsion gel production machine. Moreover, we are developing nuclear emulsion production technologies (gel production, poring and mass production). In this paper, development of nuclear emulsion technologies for the OPERA experiment, applications by the technologies and current development are described.

  6. 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 β-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.

  7. Polyaniline coated membranes for effective separation of oil-in-water emulsions.

    PubMed

    Liu, Mingming; Li, Jing; Guo, Zhiguang

    2016-04-01

    Polyaniline (PANI) decorated commercial filtration membranes, such as stainless steel meshes (SSMs) with 5μm pore size and polyvinylidene fluoride (PVDF) membranes with 2-0.22μm pore sizes, were fabricated by a simple one-step dilute polymerization at low temperature. Lots of short PANI nanofibers were firmly and uniformly coated onto the membrane surfaces, forming rough micro- and nanoscale structures and leading to underwater superoleophobicity with low oil-adhesion characteristic. Furthermore, we systematically studied the effect of pore size and pressure difference on oil-water separation ability of the obtained membranes. It was found that the PANI-modified SSMs with 5μm pore size were suitable for the separation of non-surfactant emulsions with water fluxes of more than 1000Lm(-2)h(-1) under gravity only. The PANI-modified PVDF membranes were used for the effective separation of surfactant-stabilized emulsions with water fluxes up to 3000Lm(-2)h(-1) for 2μm pore size under 0.1bar or 0.22μm pore size under 0.6bar. In addition, the superhydrophilic membranes with PANI coatings were demonstrated for high oil rejection, stable underwater superoleophobic properties after ultrasonic treatment and immersing in oils and various harsh conditions, and high and steady water permeation flux after several cycles. PMID:26809105

  8. Physico-chemical characterization of Intralipid emulsions.

    PubMed

    Rotenberg, M; Rubin, M; Bor, A; Meyuhas, D; Talmon, Y; Lichtenberg, D

    1991-11-27

    Fat emulsions containing soy triacylglycerols (100-300 g/l) and egg-yolk phospholipids (12 g/l) are often used for intravenous feeding. Previous studies have shown that these emulsions contain chylomicron-like emulsion particles of diameters of 300-400 nm and excess phospholipids aggregated as vesicles (liposomes), which remain in the infranatant upon floatation of the emulsion particles by ultracentrifugation. This work is devoted to the characterization of the commercial lipid emulsions commonly denoted Intralipids, with special emphasis on the presently ill-defined liposomes. The lipid particles composing commercial lipid emulsions (10%, 20% and 30% Intralipids, Kabivitrum Nutrition) were characterized by the combined use of physical and chemical methods. Each of the emulsions was fractionated by ultracentrifugation in saline into a 'cream' layer which floats to the top of the dispersion upon ultracentrifugation and a relatively transparent infranatant. The cream layer contains large emulsion particles of diameters ranging from 300 to 400 nm, in agreement with theoretical considerations based on their chemical composition as determined by chemical analysis. The infranatants contain about 1 g/l triacylglycerols in addition to phospholipids (from 7.2 g/l in 10% Intralipid to 2.4 g/l in 30% Intralipid) in the form of smaller particles of 70-100 nm diameter. Cryo-transmission electron microscopy shows that the infranatants contain vesicles (mostly unilamellar) at the side of residual small emulsion particles. This conclusion is also consistent with the distribution of phospholipids between outer and inner lamellae, as determined by 31P-NMR. PMID:1742317

  9. 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

  10. Hydrodynamic model for drying emulsions.

    PubMed

    Feng, Huanhuan; Sprakel, Joris; van der Gucht, Jasper

    2015-08-01

    We present a hydrodynamic model for film formation in a dense oil-in-water emulsion under a unidirectional drying stress. Water flow through the plateau borders towards the drying end leads to the buildup of a pressure gradient. When the local pressure exceeds the critical disjoining pressure, the water films between droplets break and the droplets coalesce. We show that, depending on the critical pressure and the evaporation rate, the coalescence can occur in two distinct modes. At low critical pressures and low evaporation rates, coalescence occurs throughout the sample, whereas at high critical pressures and high evaporation rate, coalescence occurs only at the front. In the latter case, an oil layer develops on top of the film, which acts as a diffusive barrier and slows down film formation. Our findings, which are summarized in a state diagram for film formation, are in agreement with recent experimental findings. PMID:26382507

  11. Hydrodynamic model for drying emulsions

    NASA Astrophysics Data System (ADS)

    Feng, Huanhuan; Sprakel, Joris; van der Gucht, Jasper

    2015-08-01

    We present a hydrodynamic model for film formation in a dense oil-in-water emulsion under a unidirectional drying stress. Water flow through the plateau borders towards the drying end leads to the buildup of a pressure gradient. When the local pressure exceeds the critical disjoining pressure, the water films between droplets break and the droplets coalesce. We show that, depending on the critical pressure and the evaporation rate, the coalescence can occur in two distinct modes. At low critical pressures and low evaporation rates, coalescence occurs throughout the sample, whereas at high critical pressures and high evaporation rate, coalescence occurs only at the front. In the latter case, an oil layer develops on top of the film, which acts as a diffusive barrier and slows down film formation. Our findings, which are summarized in a state diagram for film formation, are in agreement with recent experimental findings.

  12. Polymer/Pristine Graphene Based Composites: From Emulsions to Strong, Electrically Conducting Foams

    NASA Astrophysics Data System (ADS)

    Woltornist, Steven; Carrillo, Jan-Michael; Xu, Thomas; Dobrynin, Andrey; Adamson, Douglas

    2015-03-01

    The unique electrical, thermal and mechanical properties of graphene make it a perfect candidate for applications in graphene/graphite based polymer composites, yet challenges due to the lack of solubility of pristine graphene/graphite in water, common organic solvents, and polymer solutions and melts have limited its practical utilization. Here we report a scalable and environmentally friendly technique to form water-in-oil type emulsions stabilized by a graphitic skin consisting of overlapping pristine graphene sheets that enables the synthesis of open cell foams containing a continuous graphitic skin network. At the heart of our technique is the strong attraction of graphene to high-energy oil and water interfaces. This allows for the creation of stable water-in-oil emulsions with controlled droplet size and overlapping graphene sheets playing the role of surfactant by covering the droplet surface and stabilizing the interfaces with a thin graphitic skin. These emulsions are used as templates for the synthesis of the open cell foams with densities below 0.35 g/cm3 and exhibiting remarkable mechanical and electrical properties including compressive moduli up to ~ 100 MPa, compressive strengths of over 8.3 MPa, and bulk conductivities approaching 7 S/m.

  13. Nozzleless Fabrication of Oil-Core Biopolymeric Microcapsules by the Interfacial Gelation of Pickering Emulsion Templates.

    PubMed

    Leong, Jun-Yee; Tey, Beng-Ti; Tan, Chin-Ping; Chan, Eng-Seng

    2015-08-01

    Ionotropic gelation has been an attractive method for the fabrication of biopolymeric oil-core microcapsules due to its safe and mild processing conditions. However, the mandatory use of a nozzle system to form the microcapsules restricts the process scalability and the production of small microcapsules (<100 μm). We report, for the first time, a nozzleless and surfactant-free approach to fabricate oil-core biopolymeric microcapsules through ionotropic gelation at the interface of an O/W Pickering emulsion. This approach involves the self-assembly of calcium carbonate (CaCO3) nanoparticles at the interface of O/W emulsion droplets followed by the addition of a polyanionic biopolymer into the aqueous phase. Subsequently, CaCO3 nanoparticles are dissolved by pH reduction, thus liberating Ca(2+) ions to cross-link the surrounding polyanionic biopolymer to form a shell that encapsulates the oil droplet. We demonstrate the versatility of this method by fabricating microcapsules from different types of polyanionic biopolymers (i.e., alginate, pectin, and gellan gum) and water-immiscible liquid cores (i.e., palm olein, cyclohexane, dichloromethane, and toluene). In addition, small microcapsules with a mean size smaller than 100 μm can be produced by selecting the appropriate conventional emulsification methods available to prepare the Pickering emulsion. The simplicity and versatility of this method allows biopolymeric microcapsules to be fabricated with ease by ionotropic gelation for numerous applications. PMID:26148344

  14. 4-nitrophenol removal from aqueous solutions by emulsion liquid membranes using type I facilitation.

    PubMed

    León, G; Guzmán, M A; Miguel, B

    2013-01-01

    Nitrophenols are common organic pollutants that enter the environment during the manufacture and processing of a variety of industrial products. The removal of 4-nitrophenol (4NP) from aqueous solutions by emulsion liquid membranes using the type I facilitated transport mechanism is investigated in this paper. The liquid membrane consisted of kerosene as the organic diluent, sorbitan monooleate as the emulsifying agent and sodium hydroxide as the stripping agent. The most important operational variables governing the emulsion stability and the 4NP removal process--such as the stripper agent and surfactant concentrations, the volume ratios of membrane phase/internal phase and emulsion phase/feed phase and stirring speed - were studied and the optimal conditions of the removal process were experimentally determined. Apparent initial permeabilities of the transport process in the different operational conditions were also obtained. Ninety-eight per cent of4NP was removed in 10 minutes and an apparent initial permeability of 1.2986 min(-1) was obtained in those optimal conditions. PMID:24350486

  15. A lipid based multi-compartmental system: Liposomes-in-double emulsion for oral vaccine delivery.

    PubMed

    Liau, Jin Jau; Hook, Sarah; Prestidge, Clive A; Barnes, Timothy J

    2015-11-01

    The gastric mucosa provides the entry point for the majority of pathogens, as well as being the induction site for protective immunity; however, there remain few examples of oral vaccines due to the challenges presented by the gastrointestinal route. In this study, we develop a lipid-based multi-compartmental system for oral vaccine delivery. Specifically, we have optimised the formulation of a water-in-oil-in-water double emulsion prepared from a triglyceride - soya bean oil, using surfactants Span 80/Tween 80 and Pluronic F127 to stabilise the internal and external water phases, respectively. Into the internal water phase, we also incorporated a PEGylated liposome, prepared using hydrogenated phosphatidyl choline as a carrier for our model protein, FITC-labelled ovalbumin. We demonstrated the successful incorporation of intact liposomes into the internal water phase of the double emulsion using imaging techniques including cryo-SEM and confocal microscopy. Finally, we use in vitro release studies of FITC-ovalbumin, to provide further confirmation of the multi-compartmental structure of the double emulsion system and demonstrate significant extended release of the entrapped model antigen compared with PEG-liposomes; these characteristics are attractive for oral vaccine delivery. PMID:26455337

  16. Pulmonary surfactant for neonatal respiratory disorders.

    PubMed

    Merrill, Jeffrey D; Ballard, Roberta A

    2003-04-01

    Surfactant therapy has revolutionized neonatal care and is used routinely for preterm infants with respiratory distress syndrome. Recent investigation has further elucidated the function of surfactant-associated proteins and their contribution toward surfactant and lung immune defense functions. As the field of neonatology moves away from intubation and mechanical ventilation of preterm infants at birth toward more aggressive use of nasal continuous positive airway pressure, the optimal timing of exogenous surfactant therapy remains unclear. Evidence suggests that preterm neonates with bronchopulmonary dysplasia and prolonged mechanical ventilation also experience surfactant dysfunction; however, exogenous surfactant therapy beyond the first week of life has not been well studied. Surfactant replacement therapy has been studied for use in other respiratory disorders, including meconium aspiration syndrome and pneumonia. Commercial surfactant preparations currently available are not optimal, given the variability of surfactant protein content and their susceptibility to inhibition. Further progress in the treatment of neonatal respiratory disorders may include the development of "designer" surfactant preparations. PMID:12640270

  17. Reverse aqueous emulsions and microemulsions in HFA227 propellant stabilized by non-ionic ethoxylated amphiphiles.

    PubMed

    Chokshi, Udayan; Selvam, Parthiban; Porcar, Lionel; da Rocha, Sandro R P

    2009-03-18

    In this work we use in situ high-pressure tensiometry to screen non-ionic ethoxylated surfactants at the 1,1,1,2,3,3,3-heptafluoropropane (HFA227) propellant|Water (HFA227|W) interface. The EO(n)PO( approximately )(30)EO(n) series, where EO stands for ethylene oxide and PO for propylene oxide, and n the number of repeat EO units, was selected for this study based on the favorable interactions reported between HFA propellants and the PO moiety. The surfactants used in FDA-approved pressurized metered-dose inhaler formulations were also investigated. Tension measurements provide not only information on the relative activity of the different surfactants in the series, but they also serve as a guide for selecting an appropriate candidate for the formation of reverse aggregates based on the surfactant natural curvature. Moreover, the effect of ethanol and the chemistry of the surfactant tail group on the surfactant activity were also investigated. Surfactants with hydrogenated tails are not capable of forming stable water-in-HFA227 microemulsions. This is true even at very low tensions observed when in the presence of ethanol, indicating the lack of affinity between HFA227 and hydrogenated moieties-the surfactant does not tend to curve about water. On the other hand, PO-based amphiphiles can significantly reduce the tension of the HFA227|W interface. Small angle neutron scattering (SANS) and UV-vis spectroscopy results also reveal that a selected ethoxylated amphiphile (EO(13)PO(30)EO(13) at 1mM concentration), when in the presence of ethanol, is capable of forming stable cylindrical reverse aqueous microemulsions. EO(13)PO(30)EO(13) is also capable of forming emulsions of water-in-HFA227 that are fairly stable against coalescence. Such dispersions are potential candidates for the delivery of small polar solutes and larger therapeutic biomolecules to and through the lungs in the form of pMDI formulations, and in other medical sprays. PMID:19028557

  18. Preparation of amphiphilic glycopolymers with flexible long side chain and their use as stabilizer for emulsion polymerization.

    PubMed

    Alvrez-Paino, Marta; Juan-Rodrguez, Rafael; Cuervo-Rodrguez, Roco; Muoz-Bonilla, Alexandra; Fernndez-Garca, Marta

    2014-03-01

    A glycomonomer was synthesized from poly(ethylene glycol) methacrylate (PEGMA). The terminal hydroxyl moieties were activated with ester groups and subsequently the glucosamine was incorporated forming urethane linkages. The obtained glycomonomer was copolymerized with methyl acrylate by free radical polymerization varying the initial feed composition to produce different amphiphilic glycopolymers. The glycopolymers were then characterized and compared with the homologous glycopolymers based on 2-{[(D-glucosamin-2-N-yl)carbonyl]oxy}ethyl methacrylate. Both series of glycopolymers were used in emulsion polymerization of methyl acrylate as stabilizers without the addition of any cosurfactant. Although high conversions were not achieved with any of the employed surfactant, the glycopolymers provide good colloidal stability, spherical, monodisperse and small latex particles in comparison with the surfactant-free emulsion polymerization. The latex particles stabilized with the glycosurfactant based on PEGMA, containing a flexible spacer between the backbone and the glucosamine, lead to smooth films whereas the short side chain surfactant from 2-hydroxyethyl methacrylate (HEMA), with higher glass transition temperature, restricts the coalescence of particles and, therefore, the film formation. Moreover, the surface bioactivity of these polymer coatings was examined by analyzing their specific interaction with the lectin, Concanavalin A, Canavalia ensiformis. The specific and successful binding to the Concanavalin A was demonstrated by fluorescence microscopy for both series being more intense with increasing amount of glycounits in the glycopolymer stabilizers. Interestingly, the incorporation of a flexible spacer in the glycopolymer structures enhances the binding activity. PMID:24407696

  19. 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.

  20. 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 μg/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

  1. 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

  2. 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

  3. Injecting a droplet into a quasi-2D jammed emulsion: Fluctuations and rearrangements

    NASA Astrophysics Data System (ADS)

    Weeks, Eric R.; Hong, Xia

    We experimentally study the dynamic response of a quasi-two-dimensional emulsion to a slowly growing injected droplet. Our area fractions range from ϕ = 0 . 77 - 0 . 99 , such that the droplets are in most cases in contact with one another and are in many cases highly deformed. There is no dependence of the average flow behavior on distance to the inflation droplet, or on polydispersity or packing fraction of the emulsions. However, the fluctuations of velocity increase as the packing fraction increases. The magnitude of the fluctuations appears similar in both monodisperse, moderately ordered samples and bidisperse, disordered samples.

  4. 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.

  5. Genetics Home Reference: surfactant dysfunction

    MedlinePlus

    ... bodies. These structures are also important for some processing of surfactant proteins, which is necessary for the ... B. In addition, SFTPB gene mutations cause abnormal processing of SP-C, resulting in a lack of ...

  6. Formation of complex emulsion in microfluidic channel

    NASA Astrophysics Data System (ADS)

    Choi, Chang-Hyung; Kim, Jongmin; Lee, Chang-Soo

    2012-02-01

    We first report a novel emulsification method using two binary mixtures that produces complex emulsion by phase separation, triggered by external diffusion of separation agent dissolved in continuous phase. A disperse phase consists of monomer and D-solvent (good solvent for disperse phase), while mixture of separation-triggering agent (SA) and C-solvent (good solvent for continuous phase) is used as a continuous phase. Individual droplet was formed by microfluidic system, allowing how the separation dynamically occurs as a function of time. This system consists of the three major steps involving the transformation of a single droplet into the complex emulsion. In the first, when two immiscible phases meet at cross-junction, droplets are generated and dispersed in continuous phase containing the SA. Since the SA is only selectively soluble in the monomer of disperse phase, external diffusion of SA into the droplets through the interface occurs which initiates phase separation. In transient state, the external diffusion of the SA generates both partial separated region and SA/monomer complex at the ne