Science.gov

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 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Switchable Pickering emulsions stabilized by silica nanoparticles hydrophobized in situ with a conventional cationic surfactant.

    PubMed

    Zhu, Yue; Jiang, Jianzhong; Liu, Kaihong; Cui, Zhenggang; Binks, Bernard P

    2015-03-24

    A stable oil-in-water Pickering emulsion stabilized by negatively charged silica nanoparticles hydrophobized in situ with a trace amount of a conventional cationic surfactant can be rendered unstable on addition of an equimolar amount of an anionic surfactant. The emulsion can be subsequently restabilized by adding a similar trace amount of cationic surfactant along with rehomogenization. This destabilization-stabilization behavior can be cycled many times, demonstrating that the Pickering emulsion is switchable. The trigger is the stronger electrostatic interaction between the oppositely charged ionic surfactants compared with that between the cationic surfactant and the (initially) negatively charged particle surfaces. The cationic surfactant prefers to form ion pairs with the added anionic surfactant and thus desorbs from particle surfaces rendering them surface-inactive. This access to switchable Pickering emulsions is easier than those employing switchable surfactants, polymers, or surface-active particles, avoiding both the complicated synthesis and the stringent switching conditions. PMID:25736518

  7. 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.

  8. Antagonistic effects between magnetite nanoparticles and a hydrophobic surfactant in highly concentrated Pickering emulsions.

    PubMed

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

    2014-05-13

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

  9. 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.

  10. 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.

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

    SciTech Connect

    Ramanathan Sampath

    2005-09-30

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

  12. 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.

  13. Fluoroalkylated polyethylene glycol as potential surfactant for perfluorocarbon emulsion.

    PubMed

    Peng, C A; Hsu, Y C

    2001-11-01

    So far, perfluorocarbon (PFC) emulsions have been manufactured based mainly on two surfactants, Pluronic F-68 and egg yolk phospholipids (EYP) for clinical use. However, they have been documented to induce inflammatory or allergic responses when PFC emulsions were injected into human bloodstream. The cause of these side effects is associated with the phagocytosis of emulsified PFC microparticles by cells such as macrophages. In order to lessen the side effects, it is logic to develop surfactants, which are more phagocytosis-resistant and biocompatible. In this study, a perfluoroalkylated polyethylene glycol (R(F)-PEG) surfactant was synthesized by reacting perfluorooctanoyl chloride (C7F15COCl) with PEG of molecular weigh 8000. Both R(F)-PEG 8000 and EYP were used to make PFC emulsions separately by an ultrasonic homogenizer. Individual PFC emulsions were then incubated with mouse macrophage J774A.1 cells to examine the degree of phagocytosis. From microscopic observation of cell morphology, our results showed that the process of phagocytosis was retarded to a large extend using the R(F)-PEG surfactant. We also harnessed 19F-NMR to quantitatively detect the amount of PFC emulsions phagocytosed by J774A.1 cells. 19F-NMR result was consistent with the qualitative microscopic observation aforementioned. PMID:11795633

  14. 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

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

    PubMed

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

    2011-10-14

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

  16. The jamming elasticity of emulsions stabilized by ionic surfactants.

    PubMed

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

    2014-07-28

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

  17. 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

  18. Rheological Properties of Nanoparticle Silica-Surfactant Stabilized Crude Oil Emulsions: Influence of Temperature, Nanoparticle Concentration and Water Volume Fraction"

    NASA Astrophysics Data System (ADS)

    Kinsey, Erin; Pales, Ashley; Li, Chunyan; Mu, Linlin; Bai, Lingyun; Clifford, Heather; Darnault, Christophe

    2016-04-01

    Oil in water emulsions occur during oil extraction due to the presence of water, naturally-occurring surface-active agents and mechanical mixing in pipelines or from oil spillage. Emulsions present difficulties for use of oil in fuel and their rheological properties are important to treat environmental impacts of spills. The objective of this study is to assess the rheological characteristics of oil in water emulsions stabilized by 5% NaCl brine, Tween 20 surfactant and silica nanoparticles to gain knowledge about the behavior of oil flow in pipelines and characterize them for environmental applications. Rheological behaviors such as shear rate, shear stress, and viscosity of Prudhoe Bay crude oil emulsions were analyzed with varying percent of water volume fractions (12.5, 25 and 50%), varying weight percent of silica nanoparticles (0.001, 0.01 and 0.1 weight %), with and without 2 CMC Tween 20 nonionic surfactant. Emulsions with varying water volume fractions were analyzed at 20, 40 and 60 degrees Celsius. Flow curve analysis of the emulsions was performed using an Anton-Paar rheometer. Preliminary findings indicate that increased temperature and increasing the concentration of nanoparticles both produced lower shear stress and that the addition of surfactant decreased the viscosity and shear stress of the emulsions.

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

    NASA Astrophysics Data System (ADS)

    Szcześ, Aleksandra

    2009-02-01

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

  20. 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

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

    PubMed

    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

  2. Alginate-based emulsion template containing high oil loading stabilized by nonionic surfactants.

    PubMed

    Ong, Wan-Ding; Tey, Beng-Ti; Quek, Siew Young; Tang, Siah-Ying; Chan, Eng-Seng

    2015-01-01

    Oil-in-water (O/W) emulsion-gel systems containing high oil payloads are of increasing interest for food applications because of the reduction in encapsulation cost, consumption frequency or volume of food products. This study shows a facile approach to prepare stable alginate-based O/W emulsions at high oil loading using a mixture of nonionic surfactants (Tween 80 and Span 20) as a template to form gelled-emulsions. The synergistic effects of alginate and surfactants on the O/W emulsion properties were evaluated in terms of oil droplet size and emulsion stability. At 2% (w/v) of alginate and 1% (w/v) of surfactants, the size distribution of oil droplets was narrow and monomodal, even at an oil loading of 70% (v/v). The emulsions formed were stable against phase separation. The oil droplet size could be further reduced to below 1 μm using a high-shear homogenizer. The emulsions formed could be easily molded and gelled into solids of different shapes via ionic gelation. The findings of this study create possible avenues for applications in food industries. PMID:25529579

  3. Active Demulsification of Photoresponsive Emulsions Using Cationic-Anionic Surfactant Mixtures.

    PubMed

    Takahashi, Yutaka; Koizumi, Nanami; Kondo, Yukishige

    2016-01-26

    The influence of ultraviolet (UV) light irradiation on the emulsification properties of mixtures of an anionic surfactant, sodium dodecyl sulfate (SDS), and a photoresponsive cationic surfactant, 2-(4-(4-butylphenyl)diazenylphenoxy)ethyltrimethylammonium bromide (C4AzoTAB), containing an azobenzene group has been investigated. When mixtures of n-octane and aqueous SDS/trans-C4AzoTAB solution are homogenized, stable emulsions are obtained in regions of specific surfactant concentrations and molar ratios of the mixed surfactants. The stable emulsions are stable for over a week and found to be of the oil-in-water (O/W) type. UV light irradiation of the stable O/W emulsions leads to the coalescence of smaller oil droplets into larger ones in the emulsions, i.e., demulsification. As a result, the oil and aqueous surfactant solution phases are fully separated by UV light irradiation for 90 min, even shorter than our previous result (6 h; Langmuir 2014 , 30 , 41 - 47 ). The use of a microreactor shortens the time required for the photoinduced demulsification into 3.5 min. When mixtures of octane and aqueous SDS/cis-C4AzoTAB solution are homogenized, no emulsions are obtained. The interfacial tension (IFT) between octane and aqueous SDS/cis-C4AzoTAB solution is higher than that between octane and aqueous SDS/trans-C4AzoTAB solution, indicating that the IFT of SDS/trans-C4AzoTAB mixtures increases with the cis photoisomerization of the trans isomer. These results suggest that cis isomerization of the SDS/trans-C4AzoTAB mixtures due to UV light irradiation causes Ostwald ripening of the octane droplets in the emulsions, thereby reducing the interfacial area between the octane and water phases as the IFT between octane and the aqueous surfactant solution increases. Subsequently, the octane and aqueous solution phases separate. PMID:26731043

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

    PubMed Central

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

    2009-01-01

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

  5. 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.

  6. 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

  7. Effect of surfactant concentration on the flotation of hydrocarbons from their emulsions. II. Removal of hexadecane

    SciTech Connect

    Medrzycka, K.B.; Zwierzykowski, W.

    1987-06-01

    Flotation of hydrocarbons from their aqueous emulsions depends to a considerable extent on the efficiency of the collision of air bubbles with the emulsified globules. The collision efficiency greatly depends on the surface energy of the boundaries: air-water, hydrocarbon-water, and hydrocarbon-air. Two of the parameters which influence those energies are type and concentration of the surface-active compound present in the flotation system. It was stated in a previous paper that the lower surfactant concentration, the more effective is the flotation of mesitylene from it emulsion. The authors suppose that in the case of the flotation of hexadecane the dependence will be similar. They also expect that flotation without any surfactant will be the most effective.

  8. P450cam biocatalysis in surfactant-stabilized two-phase emulsions.

    PubMed

    Ryan, Jessica D; Clark, Douglas S

    2008-04-15

    Cytochrome P450 monooxygenases (P450s) are powerful biocatalysts that have the ability to oxidize a broad range of substrates, often at non-reactive carbon centers. However, incorporation of P450s into synthetic schemes has so far been limited to a few whole-cell transformations. P450 substrates are often hydrophobic and have low water solubility, limiting the amount of product that can be produced. To help overcome this limitation, we have examined P450cam activity in two-phase hexane/water emulsions with and without the anionic surfactant, bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT). Hydroxylation of camphor to hydroxycamphor by the three- component P450cam system was chosen as the model reaction, and regeneration of NADH was accomplished with yeast alcohol dehydrogenase (YADH). P450cam was activated in the surfactant-free emulsions, and addition of AOT improved the activity even further, at least over the range of camphor concentrations for which initial rates were readily measurable in all media. The largest observed rate enhancement was 4.5-fold. Nearly 50-times more product was formed in the surfactant-stabilized emulsions than was achieved in aqueous buffer, with total turnover numbers reaching 28,900 for P450cam and 11,800 for YADH. In the absence of surfactant, the two-phase reaction appeared to be mass-transfer limited, while inclusion of AOT alleviated transport limitations and/or afforded a larger interfacial area for P450 activation. The oxidation of hydroxycamphor to 2,5-diketocamphane was also observed, owing to the large concentration of hydroxycamphor relative to camphor in the aqueous phase of the two-phase emulsion. This competing reaction was accompanied by the uncoupled oxidation of NADH (i.e., NADH oxidation without formation of 2,5-diketocamphane), which reduced the availability of NADH for camphor oxidation and further limited the yield of hydroxycamphor in the two-phase emulsions. These results indicate that a surfactant

  9. 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

  10. 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

  11. 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

  12. Phase Behavior of Dilute Carbon Black Suspensions and Carbon Black Stabilized Emulsions

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    We use para-amino benzoic acid terminated carbon black (CB) as a tunable model particulate material to study the effect of inter-particle interactions on phase behavior and steady shear stresses in suspensions and particle-stabilized emulsions. We modulate inter-particle interactions by adding NaCl to the suspension, thus salting surface carboxylate groups. Surprisingly, yield stress behavior emerged at a volume fraction of CB as low as ϕCB = 0.008, and gel behavior was observed at ϕCB >0.05, well below the percolation threshold for non-interacting particles. The yield stress was found to grow rapidly with carbon black concentration suggesting that salt-induced hydrophobicity leads to strong inter-particle interactions and the formation of a network at low particle concentrations. The yield stresses of CB-stabilized emulsions also grows rapidly with carbon black concentrations, implying that inter-droplet interactions can be induced through the tuning of carbon black concentration in emulsion systems. Emulsions stabilized by ionic surfactants show no inter-droplet interactions. In contrast, oil droplets in the CB-stabilized emulsion move collectively or are immobilized because of an interconnected CB network in the aqueous phase.

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

    PubMed

    Lu, Dongwei; Zhang, Tao; Ma, Jun

    2015-04-01

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

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

    PubMed

    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. PMID:24206328

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

    NASA Astrophysics Data System (ADS)

    Ryoo, Won Sun

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

  17. Influence of droplet characteristics on the formation of oil-in-water emulsions stabilized by surfactant-chitosan layers.

    PubMed

    Mun, Saehun; Decker, Eric A; McClements, D Julian

    2005-07-01

    The objective of this study was to establish the optimum conditions for preparing stable oil-in-water emulsions containing droplets surrounded by surfactant-chitosan layers. A primary emulsion containing small droplets (d32 approximately = 0.3 microm) was prepared by homogenizing 20 wt% corn oil with 80 wt% emulsifier solution (20 mM SDS, 100 mM acetate buffer, pH 3) using a high-pressure valve homogenizer. The primary emulsion was diluted with chitosan solutions to produce secondary emulsions with a range of oil and chitosan concentrations (0.5-10 wt% corn oil, 0-1 wt% chitosan, pH 3). The secondary emulsions were sonicated to help disrupt any droplet aggregates formed during the mixing process. The electrical charge, particle size, and amount of free chitosan in the emulsions were then measured. The droplet charge changed from negative to positive as the amount of chitosan in the emulsions was increased, reaching a relatively constant value (approximately +50 mV) above a critical chitosan concentration (C(Sat)), which indicated that saturation of the droplet surfaces with chitosan occurred. Extremely large droplet aggregates were formed at chitosan concentrations below C(Sat), but stable emulsions could be formed above C(Sat) provided the droplet concentration was not high enough for depletion flocculation to occur. Interestingly, we found that stable multilayer emulsions could also be formed by mixing chitosan with an emulsion stabilized by a nonionic surfactant (Tween 20) due to the fact the initial droplets had some negative charge. The information obtained from this study is useful for preparing emulsions stabilized by multilayer interfacial layers. PMID:15982024

  18. 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

  19. Coalescence kinetics in surfactant stabilized emulsions: evolution equations from direct numerical simulations.

    PubMed

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

    2012-12-01

    Lattice Boltzmann simulations were used to study the coalescence kinetics in emulsions with amphiphilic surfactant, under neutrally buoyant conditions, and with a significant kinematic viscosity contrast between the phases (emulating water in oil emulsions). The 3D simulation domain was large enough (256(3) ~ 10(7) 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 n(d)(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 n(d)) were established in terms of the instantaneous values of the kinetic energy, coalescence probability, Gibbs elasticity, and interfacial area. The model studies indicated that true power laws for the growth of the droplet size and decrease of the number of droplets with time may not be justified, since the exponents derived using the phenomenological model were time dependent. In contrast to earlier simulation results for symmetric blends with surfactant, we found no evidence for stretched logarithmic scaling of the form D ~ [ln (ct)](α) for the morphology length, or exponential scalings associated with arrested growth, on the basis of the phenomenological model. PMID:23231250

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

    SciTech Connect

    Rocha, S.R.P. da; Harrison, K.L.; Johnston, K.P.

    1999-01-19

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    Lyotropic chromonic liquid crystals, assembled by non-covalent interactions, have fascinating temperature- and concentration-dependent phase behavior. Using water-oil-water double emulsions, we are able control the inner droplet chromonic phase concentration by osmosis through the oil phase. We then study the configurations of the chromonic liquid crystal phases in droplets by varying the oil types, oil soluble surfactants, and inner droplet diameter. We employ polarization microscopy to observe resulting nematic and columnar phases of Sunset Yellow FCF, and we deduce the liquid crystal configuration of both phases within the droplets. Simulations based on Jones matrices confirm droplet appearance, and preliminary observations of chromonic liquid crystal shells in oil-water-oil double emulsions are reported. Supported by UPenn MRSEC DMR 11-20901 and NSF DMR 12-05463

  3. 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.

  4. 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.

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

    PubMed

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

    2010-11-15

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

  6. 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

  7. 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.

  8. Effect of molecular weight and degree of deacetylation of chitosan on the formation of oil-in-water emulsions stabilized by surfactant-chitosan membranes.

    PubMed

    Mun, Saehun; Decker, Eric A; McClements, D Julian

    2006-04-15

    The objective of this study was to establish the influence of polyelectrolyte characteristics (molecular weight and charge density) on the properties of oil-in-water emulsions containing oil droplets surrounded by surfactant-polyelectrolyte layers. A surfactant-stabilized emulsion containing small droplets (d32 approximately 0.3 microm) was prepared by homogenizing 20 wt% corn oil with 80 wt% emulsifier solution (20 mM SDS or 2.5 wt% Tween 20, 100 mM acetate buffer, pH 3) using a high-pressure valve homogenizer. This primary emulsion was then diluted with various chitosan solutions to produce secondary emulsions with a range of chitosan concentrations (3 wt% corn oil, 0-1 wt% chitosan). The influence of the molecular characteristics of chitosan on the properties of these emulsions was examined by using chitosan ingredients with different molecular weights (MW approximately 15, 145, and 200 kDa) and degree of deacetylation (DDA approximately 40, 77, and 92%). The electrical charge and particle size of the secondary emulsions were then measured. Extensive droplet aggregation occurred when the chitosan concentration was below the amount required to saturate the droplet surfaces, but stable emulsions could be formed at higher chitosan concentrations. The zeta-potential and mean diameter (d32) of the particles in the secondary emulsions was not strongly influenced by chitosan MW, however the chitosan with the lowest DDA (40%) produced droplets with smaller mean diameters and zeta-potentials than the other two DDA samples examined. Interestingly, we found that stable multilayer emulsions could be formed by mixing medium or high MW chitosan with an emulsion stabilized by a non-ionic surfactant (Tween 20) due to the fact the initial droplets had some negative charge. The information obtained from this study is useful for preparing emulsions stabilized by multilayer interfacial layers. PMID:16203009

  9. Adsorption of Anionic or Cationic Surfactants in Polyanionic Brushes and Its Effect on Brush Swelling and Fouling Resistance during Emulsion Filtration.

    PubMed

    Yang, Zhefei; Tarabara, Volodymyr V; Bruening, Merlin L

    2015-11-01

    Atom transfer radical polymerization of ionic monomers from membrane surfaces yields polyelectrolyte brushes that swell in water and repel oil droplets to resist fouling during filtration of oil-in-water emulsions. However, surfactant adsorption to polyelectrolyte brushes may overcome this fouling resistance. This work examines adsorption of cationic and anionic surfactants in polyanionic brushes and the effect of these surfactants on emulsion filtration. In situ ellipsometry with films on flat surfaces shows that brushes composed of poly(3-sulfopropyl methacrylate salts) (pSPMK) swell 280% in water and do not adsorb sodium dodecyl sulfate (SDS). pSPMK-modified microfiltration membranes reject >99.9% of the oil from SDS-stabilized submicron emulsions, and the specific flux through these modified membranes is comparable to that through NF270 nanofiltration membranes. Moreover, the brush-modified membranes show no decline in flux over a 12 h filtration, whereas the flux through NF270 membranes decreases by 98.7%. In contrast, pSPMK brushes adsorb large quantities of cetyltrimethylammonium bromide (CTAB), and at low chain densities the brushes collapse in the presence of this cationic surfactant. Filtration of CTAB-stabilized emulsions through pSPMK-modified membranes gives minimal oil rejection, presumably due to the brush collapse. Thus, the fouling resistance of polyelectrolyte brush-modified membranes clearly depends on the surfactant composition in a particular emulsion. PMID:26442835

  10. 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

  11. 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

  12. Flexible Hierarchical TiO2/Fe2O3 Composite Membrane with High Separation Efficiency for Surfactant-Stabilized Oil-Water Emulsions.

    PubMed

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

    2016-02-18

    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/Fe2O3 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/Fe2O3 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

  13. 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. ...

  14. 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...

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

    NASA Astrophysics Data System (ADS)

    MacLean, Duncan A.

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

  16. 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

  17. 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

  18. Surfactant effects on environmental behavior of pesticides.

    PubMed

    Katagi, Toshiyuki

    2008-01-01

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

  19. Controlling block copolymer phase behavior using ionic surfactant

    NASA Astrophysics Data System (ADS)

    Ray, D.; Aswal, V. K.

    2016-05-01

    The phase behavior of poly(ethylene oxide)-poly(propylene oxide-poly(ethylene oxide) PEO-PPO-PEO triblock copolymer [P85 (EO26PO39EO26)] in presence of anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solution as a function of temperature has been studied using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations (1 wt%) of block copolymer and surfactants. Each of the individual components (block copolymer and surfactant) and the nanoparticle-surfactant mixed system have been examined at varying temperature. The block copolymer P85 forms spherical micelles at room temperature whereas shows sphere-to-rod like micelle transition at higher temperatures. On the other hand, SDS surfactant forms ellipsoidal micelles over a wide temperature range. Interestingly, it is found that phase behavior of mixed micellar system (P85 + SDS) as a function of temperature is drastically different from that of P85, giving the control over the temperature-dependent phase behavior of block copolymers.

  20. Use of Biobased Surfactants to Stabilize Emulsions Relevant for Industrial Lubrication

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Emulsion based lubricants are used widely in metalworking, mining, fire-resistant hydraulic applications, and more, due to their low cost high performance. Key emulsification factors, such as appearance, particle size distribution and stability, are very important to lubricant applications. Water ...

  1. 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

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

    PubMed

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

    2012-10-15

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

  3. Surfactant-free emulsions stabilized by tempo-oxidized bacterial cellulose.

    PubMed

    Jia, Yuanyuan; Zhai, Xiaoli; Fu, Wei; Liu, Yang; Li, Fei; Zhong, Cheng

    2016-10-20

    In order to seek a safe, biodegradable, and sustainable solid stabilizer for food, topical and pharmaceutical emulsions, individualized cellulose nanofibers were prepared by oxidizing bacterial cellulose (BC) in a Tempo-mediated system; their ability to stabilize oil/water interface was investigated. Significant amounts of C6 carboxylate groups were selectively formed on each cellulose microfibril surface, so that the hydrophilicity was strengthened, leading to lower contact angles. Meanwhile, both the length and width of fibrils were decreased significantly, by partial cleavage of numerous numbers of inter- and intra-fibrillar hydrogen bonds. Tempo-oxidized BC (TOBC) was more effective than BC in stabilizing oil-water interface, attributing to the much smaller size. Fibril dosage and oxidation degree exerted a great influence on the stability and particle size distribution of emulsion samples. When the fibril dosage was 0.7wt.%, the sample was so stable that it did not experience creaming and coalescence over 8 months. The 2-TOBC coated droplets showed the greatest stability, although both the zeta potential and the electric repulsion were the largest for the 10-TOBC analogue, which was manipulated by the wettability of fibrils. In addition, the stability of samples was analyzed from the viewpoint of particle size distribution. Consequently, fibril size and wettability are two counterbalanced factors influencing the stability of TOBC-stabilized emulsions; a combination of suitable wettability and size imparts TOBC-stabilized emulsion high stability. As a kind of biomass-based particle stabilizer, TOBC showed great potential applications in food, topical and pharmaceutical formulations. PMID:27474639

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

    SciTech Connect

    Pal, R.

    1995-04-01

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

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

    PubMed

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

    2007-02-13

    The interaction forces in emulsion films stabilized using hydrophobically modified inulin (INUTEC SP1) were investigated by measuring the disjoining pressure of a microscopic horizontal film between two macroscopic emulsion drops of isoparaffinic oil (Isopar M). A special measuring cell was used for this purpose whereby the disjoining pressure Pi was measured as a function of the equivalent film thickness hw. The latter was determined using an interferometric method. In this way Pi-hw curves were established at a constant INUTEC SP1 concentration of 2x10(-5) mol.dm-3 and at various NaCl concentrations. At a constant disjoining pressure of 36 Pa, a constant temperature of 22 degrees C, and a film radius of 100 microm, hw decreased with an increase in the NaCl concentration, Cel, and reached a constant value of 11 nm at Cel=5x10(-2) mol.dm-3. This reduction in film thickness is due to the compression of the electrical double layer, and at the above critical NaCl concentration any electrostatic repulsion is removed and only steric interaction remains. This critical electrolyte concentration represents the transition from electrostatic to steric interaction. At a NaCl concentration of 2x10(-4) mol.dm-3 the Pi-hw isotherms showed a gradual decrease in hw with an increase in capillary pressure, after which there was a jump in hw from approximately 30 to approximately 7.2 nm when Pi reached a high value of 2-5.5 kPa. This jump is due to the formation of a Newton black film (NBF), giving a layer thickness of the polyfructose loops of approximately 3.6 nm. The film thickness did not change further when the pressure reached 45 kPa, indicating the high stability of the film. Pi-hw isotherms were obtained at various NaCl concentrations, namely, 5x10(-2), 5x10(-1), 1.0, and 2.0 mol.dm-3. The initial thicknesses are within the range 9-11 nm, after which a transition zone starts, corresponding to a pressure of about 0.5 kPa. In this zone all films transform to an NBF with a jump

  6. Influence of interfacial area on the rheological behavior of heavy oil emulsions

    NASA Astrophysics Data System (ADS)

    Soto, Enrique; Ramírez-González, Patsy V.; de la Torre, Rocío G.; Guadarrama-Cetina, José M.; Quiñones-Cisneros, Sergio H.

    2014-03-01

    Experimental observations of the rheological behavior of heavy oil emulsions ARE presented. The emulsions were prepared from mixtures of the oil and brine in different rations and controlled mixing conditions. It was observed that the oil is the continuous phase and the brine the dispersed one. The drop size distribution and water fraction were measured from digital images obtained by a camera and a microscopy. The viscosity of the emulsions increases, when the drop size decreases and The interfacial area increases. The fluid exhibits a shear thinning and elastic rheological behavior below a critical drop size and concentration. The emulsions are stable for long periods of time. The increase in viscosity and non Newtonian behavior are strongly related to the interfacial area.

  7. 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

  8. 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

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

    PubMed

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

    2010-04-15

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

  10. Emulsifying potency of new amino acid-type surfactant (II): stable water-in-oil (W/O) emulsions containing 85 wt% inner water phase.

    PubMed

    Yokoyama, S; Kouchi, J; Tabohashi, T; Harusawa, F; Yamaguchi, A; Sakai, H; Abe, M

    2001-10-01

    The ternary phase diagram for N-[3-lauryloxy-2-hydroxypropyl]-L-arginine L-glutamate (C12HEA-Glu), a new amino acid-type surfactant, /oleic acid (OA)/water system was established. The liquid crystal and gel complex formations between C12HEA-Glu and OA were applied to a preparation of water-in-oil (W/O) emulsions. Stable W/O emulsions containing liquid paraffin (LP) as the oil and a mixture of C12HEA-Glu and OA as the emulsifier were formed. The preparation of stable W/O emulsions containing 85 wt% water phase was also possible, in which water droplets would be polygonally transformed and closely packed, since the maximum percentage of inner phase is 74% assuming uniformly spherical droplets. Water droplets would be taken into the liquid crystalline phase (or the gel complex) and the immovable water droplets would stabilize the W/O emulsion system. The viscosity of emulsions abruptly increased above the 75 wt% water phase (dispersed phase). The stability of W/O emulsions with a lower weight ratio of OA to C12HEA-Glu and a higher ratio of water phase was greater. This unusual phenomenon may be related to the formation of a liquid crystalline phase between C12HEA-Glu and OA, and the stability of the liquid crystal at a lower ratio of oil (continuous phase). W/O and oil-in-water (O/W) emulsions containing LP were selectively prepared using a mixture of C12HEA-Glu and OA since the desirable hydrophile-lipophile balance (HLB) number for the emulsification was obtainable by mixing the two emulsifiers. PMID:11605664

  11. Modeling Thermodynamic Behavior of Nonionic Surfactants in Water

    NASA Astrophysics Data System (ADS)

    Ginzburg, Valeriy; Varineau, Pierre

    2009-03-01

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

  12. 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

  13. 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

  14. Rheological behavior of aqueous dispersions containing blends of rhamsan and welan polysaccharides with an eco-friendly surfactant.

    PubMed

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

    2016-09-01

    Small amplitude oscillatory shear and steady shear flow properties of rhamsan gum and welan gum dispersions containing an eco-friendly surfactant (a polyoxyethylene glycerol ester) formulated to mimic the continuous phase of O/W emulsions were studied using the surface response methodology. A second order polynomial equation fitted the influence of surfactant concentration, rhamsan/welan mass ratio and total concentration of polysaccharides. Systems containing blends of rhamsan and welan did not show synergism but thermodynamic incompatibility and made it possible to adjust the linear viscoelastic and low shear rate flow properties to achieve values in between those of systems containing either rhamsan or welan as the only polysaccharide. All the systems studied exhibited weak gel rheological properties as the mechanical spectra displayed the plateau or rubber-like relaxation zone, the linear viscoelastic range was rather narrow and flow curves presented shear thinning behavior, which fitted the power-law equation. While mechanical spectra of the systems studied demonstrated that they did not control the linear viscoelastic properties of the corresponding emulsions, the blend of rhamsan and welan gums was able to control the steady shear flow properties. PMID:27232306

  15. Characterization of flaxseed oil emulsions.

    PubMed

    Lee, Pei-En; Choo, Wee-Sim

    2015-07-01

    The emulsifying capacity of surfactants (polysorbate 20, polysorbate 80 and soy lecithin) and proteins (soy protein isolate and whey protein isolate) in flaxseed oil was measured based on 1 % (w/w) of emulsifier. Surfactants showed significantly higher emulsifying capacity compared to the proteins (soy protein isolate and whey protein isolate) in flaxseed oil. The emulsion stability of the flaxseed oil emulsions with whey protein isolate (10 % w/w) prepared using a mixer was ranked in the following order: 1,000 rpm (58 min) ≈ 1,000 rpm (29 min) ≈ 2,000 rpm (35 min) >2,000 rpm (17.5 min). The emulsion stability of the flaxseed oil emulsions with whey protein isolate (10 % w/w) prepared using a homogenizer (Ultra Turrax) was independent of the speed and mixing time. The mean particle size of the flaxseed oil emulsions prepared using the two mixing devices ranged from 23.99 ± 1.34 μm to 47.22 ± 1.99 μm where else the particle size distribution and microstructure of the flaxseed oil emulsions demonstrated using microscopic imaging were quite similar. The flaxseed oil emulsions had a similar apparent viscosity and exhibited shear thinning (pseudoplastic) behavior. The flaxseed oil emulsions had L* value above 70 and was in the red-yellow color region (positive a* and b* values). PMID:26139903

  16. Synthesis and aggregation behavior of a hexameric quaternary ammonium surfactant.

    PubMed

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

    2011-09-01

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

  17. Emulsion formation at the Pore-Scale

    NASA Astrophysics Data System (ADS)

    Armstrong, R. T.; Van Den Bos, P.; Berg, S.

    2012-12-01

    The use of surfactant cocktails to produce ultra-low interfacial tension between water and oil is an enhanced oil recovery method. In phase behavior tests three distinct emulsion phases are observed: (1) oil-in-water emulsion; (2) microemulsion; and (3) water-in-oil emulsion. However, it is unknown how phase behavior manifests at the pore-scale in a porous media system. What is the time scale needed for microemulsion formation? Where in the pore-space do the microemulsions form? And in what order do the different emulsion phases arrange during oil bank formation? To answer these questions micromodel experiments were conducted. These experiments are used to build a conceptual model for phase behavior at the pore-scale.

  18. Polymerization in emulsion microdroplet reactors

    NASA Astrophysics Data System (ADS)

    Carroll, Nick J.

    concentration and micellization of the surfactant. At the same time, the silica solidifies around the surfactant structures, forming equally sized mesoporous particles. The procedure can be tuned to produce well-separated particles or alternatively particles that are linked together. The latter allows us to create 2D or 3D structures with hierarchical porosity. Oil, water, and surfactant liquid mixtures exhibit very complex phase behavior. Depending on the conditions, such mixtures give rise to highly organized structures. A proper selection of the type and concentration of surfactants determines the structuring at the nanoscale level. In this work, we show that hierarchically bimodal nanoporous structures can be obtained by templating silica microparticles with a specially designed surfactant micelle/microemulsion mixture. Tuning the phase state by adjusting the surfactant composition and concentration allows for the controlled design of a system where microemulsion droplets coexist with smaller surfactant micellar structures. The microemulsion droplet and micellar dimensions determine the two types of pore sizes (single nanometers and tens of nanometers). We also demonstrate the fabrication of carbon and carbon/platinum replicas of the silica microspheres using a "lost-wax" approach. Such particles have great potential for the design of electrocatalysts for fuel cells, chromatography separations, and other applications. It was determined that slight variations in microemulsion mixture components (electrolyte concentration, wt% of surfactants, oil to sol ratio, etc.) produces strikingly different pore morphologies and particle surface areas. Control over the size and structure of the smaller micelle-templated pores was made possible by varying the length of the hydrocarbon block within the trimethyl ammonium bromide surfactant and characterized using X-ray diffraction. The effect of emulsion aging was studied by synthesizing particles at progressive time levels from a sample

  19. 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.

  20. Effect of Phytosterols on the Crystallization Behavior of Oil-in-Water Milk Fat Emulsions.

    PubMed

    Zychowski, Lisa M; Logan, Amy; Augustin, Mary Ann; Kelly, Alan L; Zabara, Alexandru; O'Mahony, James A; Conn, Charlotte E; Auty, Mark A E

    2016-08-31

    Milk has been used commercially as a carrier for phytosterols, but there is limited knowledge on the effect of added plant sterols on the properties of the system. In this study, phytosterols dispersed in milk fat at a level of 0.3 or 0.6% were homogenized with an aqueous dispersion of whey protein isolate (WPI). The particle size, morphology, ζ-potential, and stability of the emulsions were investigated. Emulsion crystallization properties were examined through the use of differential scanning calorimetry (DSC) and Synchrotron X-ray scattering at both small and wide angles. Phytosterol enrichment influenced the particle size and physical appearance of the emulsion droplets, but did not affect the stability or charge of the dispersed particles. DSC data demonstrated that, at the higher level of phytosterol addition, crystallization of milk fat was delayed, whereas, at the lower level, phytosterol enrichment induced nucleation and emulsion crystallization. These differences were attributed to the formation of separate phytosterol crystals within the emulsions at the high phytosterol concentration, as characterized by Synchrotron X-ray measurements. X-ray scattering patterns demonstrated the ability of the phytosterol to integrate within the milk fat triacylglycerol matrix, with a concomitant increase in longitudinal packing and system disorder. Understanding the consequences of adding phytosterols, on the physical and crystalline behavior of emulsions may enable the functional food industry to design more physically and chemically stable products. PMID:27476512

  1. 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.

  2. 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

  3. Antioxidant Behavior of Olive Phenolics in Oil-in-Water Emulsions.

    PubMed

    Paradiso, Vito Michele; Di Mattia, Carla; Giarnetti, Mariagrazia; Chiarini, Marco; Andrich, Lucia; Caponio, Francesco

    2016-07-27

    The effect of the surrounding molecular environment (β-lactoglobulin as an emulsion stabilizer and maltodextrin as a viscosity modifier) on the antioxidant activity of three olive oil phenolic compounds (PCs) in olive oil-in-water emulsions was investigated. Oxidation potential, phenolic partitioning, and radical quenching capacity were assessed in solution and in emulsion for oleuropein, hydroxytyrosol, and tyrosol; the influence of β-lactoglobulin and maltodextrin concentration was also evaluated. Finally, the observed properties were related to the oxidative stability of the emulsions containing the PCs to explain their behavior. The order hydroxytyrosol > oleuropein > tyrosol was observed among the antioxidants for both oxidation potential and radical quenching activity. Radical quenching capacity in emulsion and anodic potential were complementary indices of antioxidant effectiveness. As the intrinsic susceptibility of an antioxidant to oxidation expressed by its anodic potential decreased, the environmental conditions (molecular interactions and changes in continuous phase viscosity) played a major role in the antioxidant effectiveness in preventing hydroperoxide decomposition. PMID:27380032

  4. Phase behavior of polyion-surfactant ion complex salts: effects of surfactant chain length and polyion length.

    PubMed

    Svensson, Anna; Norrman, Jens; Piculell, Lennart

    2006-06-01

    The aqueous phase behavior of a series of complex salts, containing cationic surfactants with polymeric counterions, has been investigated by visual inspection and small-angle X-ray scattering (SAXS). The salts were alkyltrimethylammonium polyacrylates, CxTAPAy, based on all combinations of five surfactant chain lengths (C6, C8, C10, C12, and C16) and two lengths of the polyacrylate chain (30 and 6 000 repeating units). At low water contents, all complex salts except C6TAPA6000 formed hexagonal and/or cubic Pm3n phases, with the hexagonal phase being favored by lower water contents. The aggregate dimensions in the liquid crystalline phases changed with the surfactant chain length. The determined micellar aggregation numbers of the cubic phases indicated that the micelles were only slightly aspherical. At high water contents, the C6TAPAy salts were miscible with water, whereas the other complex salts featured wide miscibility gaps with a concentrated phase in equilibrium with a (sometimes very) dilute aqueous solution. Thus, the attraction between oppositely charged surfactant aggregates and polyions decreases with decreasing surfactant chain length, and with decreasing polyion length, resulting in an increased miscibility with water. The complex salt with the longest surfactant chains and polyions gave the widest miscibility gap, with a concentrated hexagonal phase in equilibrium with almost pure water. A decrease in the attraction led to cubic-micellar and micellar-micellar coexistence in the miscibility gap and to an increasing concentration of the complex salt in the dilute phase. For each polyion length, the mixtures for the various surfactant chain lengths were found to conform to a global phase diagram, where the surfactant chain length played the role of an interaction parameter. PMID:16722736

  5. 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

  6. Identification of phases of various oil, surfactant/ co-surfactants and water system by ternary phase diagram.

    PubMed

    Syed, Haroon K; Peh, Kok K

    2014-01-01

    The objective of this study was to select appropriate surfactants or blends of surfactants and oil to study the ternary phase diagram behavior and identify various phases obtained from the oil and surfactant/surfactant mixture combinations of different HLB. The phases include conventional emulsion, gel/viscous and transparent/translucent microemulsion. Pseudoternary phase diagrams of water, oil and S/Smix of various HLB values range of 9.65-15 were constructed by using water titration method at room temperature. Visual analysis, conductivity and dye dilution test (methylene blue) were performed after each addition and mixing of water, to identify phases as microemulsion, o/w or w/o emulsion (turbid/milky) and transparent gel/turbid viscous. High gel or viscous area was obtained with Tween 80 and surfactant mixture of Tween 80 and Span 80 with all oils. The results indicated that non-ionic surfactants and PG of different HLB values exhibited different pseudoternary phase diagram characteristics but no microemulsions originated from mineral and olive oils. The w/o emulsion occupied a large area in the ternary phase triangle when HLB value of the surfactant/Smix decreased. The o/w emulsion area was large with increasing HLB value of surfactant/Smix. PMID:25272651

  7. 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.

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

    PubMed

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

    2015-02-28

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

  9. 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

  10. PHASE BEHAVIOR OF WATER/PERCHLOROETHYLENE/ANIONIC SURFACTANT SYSTEMS

    EPA Science Inventory

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

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

    PubMed

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

    2012-04-01

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

  12. 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

  13. Topical delivery of lipophilic drugs from o/w Pickering emulsions.

    PubMed

    Frelichowska, Justyna; Bolzinger, Marie-Alexandrine; Pelletier, Jocelyne; Valour, Jean-Pierre; Chevalier, Yves

    2009-04-17

    Surfactant-free emulsions stabilized by solid particles (Pickering emulsions) have been evaluated in the terms of skin absorption of lipophilic drugs. The behavior of three formulations: a surfactant-based emulsion, a Pickering emulsion stabilized by silica particles and a solution in triglyceride oil, were compared in order to assess the effect of the surface coating of Pickering emulsions as new dosage forms for topical application. Such comparative investigation was performed in vitro on excised pig skin in Franz diffusion cells with all-trans retinol as model lipophilic drug. Surfactant-based (classical, CE) and Pickering (PE) oil-in-water emulsions containing retinol were prepared with the same chemical composition (except the stabilizing agent: surfactant or silica particles), the same droplet size and the same viscosity. No permeation through the skin sample was observed after 24h exposure because of the high lipophilic character of retinol. Penetration of retinol was 5-fold larger for both CE and PE than for the solution in triglyceride. The distribution of retinol inside the skin layers depended significantly on the emulsions type: the classical emulsion allowed easy diffusion through the stratum corneum, so that large amounts reached the viable epidermis and dermis. Conversely, high storage of retinol inside the stratum corneum was favored by the Pickering emulsion. The retinol content in stratum corneum evaluated by skin stripping, demonstrated the increased retinol accumulation from PE. Therefore Pickering emulsions are new drug penetration vehicles with specific behavior; they are well-suited either for targeting the stratum corneum or aimed at slow release of drug from stratum corneum used as a reservoir to the deeper layers of skin. PMID:19135516

  14. Surfactant-adsorption-induced initial depinning behavior in evaporating water and nanofluid sessile droplets.

    PubMed

    Zhong, Xin; Duan, Fei

    2015-05-19

    A surfactant-induced autophobic effect has been observed to initiate an intense depinning behavior at the initial stage of evaporation in both pure water and nanofluid sessile droplets. The cationic surfactant adsorbing to the negatively charged silicon wafer makes the solid surface more hydrophobic. The autophobing-induced depinning behavior, leading to an enlarged contact angle and a shortened base diameter, takes place only when the surfactant concentration is below its critical micelle concentration (cmc). The initial spreading degree right before the droplet retraction, the retracting velocity of the contact line, and the duration of the initial droplet retraction are shown to depend negatively on the surfactant concentration below the cmc. An unexpected enhancement in the initial depinning has been found in the nanofluid droplets, possibly resulting from the hydrophilic interplay between the graphite nanoparticle deposition and the surfactant molecules. Such promotion of the initial depinning due to the nanoparticle deposition makes the droplet retract even at a surfactant concentration higher than the cmc (1.5 cmc). The resulting deposition formed in the presence of the depinning behavior has great enhancement for coffee-ring formation as compared to the one free of surfactant, implying that the formation of a coffee ring does not require the pinning of the contact line during the entire drying process. PMID:25923721

  15. 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

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

    PubMed

    Wang, Peng; Keller, Arturo A

    2008-08-01

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

  17. 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

  18. 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.

  19. Polymerization in emulsion microdroplet reactors

    NASA Astrophysics Data System (ADS)

    Carroll, Nick J.

    concentration and micellization of the surfactant. At the same time, the silica solidifies around the surfactant structures, forming equally sized mesoporous particles. The procedure can be tuned to produce well-separated particles or alternatively particles that are linked together. The latter allows us to create 2D or 3D structures with hierarchical porosity. Oil, water, and surfactant liquid mixtures exhibit very complex phase behavior. Depending on the conditions, such mixtures give rise to highly organized structures. A proper selection of the type and concentration of surfactants determines the structuring at the nanoscale level. In this work, we show that hierarchically bimodal nanoporous structures can be obtained by templating silica microparticles with a specially designed surfactant micelle/microemulsion mixture. Tuning the phase state by adjusting the surfactant composition and concentration allows for the controlled design of a system where microemulsion droplets coexist with smaller surfactant micellar structures. The microemulsion droplet and micellar dimensions determine the two types of pore sizes (single nanometers and tens of nanometers). We also demonstrate the fabrication of carbon and carbon/platinum replicas of the silica microspheres using a "lost-wax" approach. Such particles have great potential for the design of electrocatalysts for fuel cells, chromatography separations, and other applications. It was determined that slight variations in microemulsion mixture components (electrolyte concentration, wt% of surfactants, oil to sol ratio, etc.) produces strikingly different pore morphologies and particle surface areas. Control over the size and structure of the smaller micelle-templated pores was made possible by varying the length of the hydrocarbon block within the trimethyl ammonium bromide surfactant and characterized using X-ray diffraction. The effect of emulsion aging was studied by synthesizing particles at progressive time levels from a sample

  20. Self-aggregation and liquid crystalline behavior of new ester-functionalized quinuclidinolium surfactants.

    PubMed

    Bhadani, Avinash; Endo, Takeshi; Koura, Setsuko; Sakai, Kenichi; Abe, Masahiko; Sakai, Hideki

    2014-08-01

    A new type of ester-based cationic surfactant having a quinuclidinolium headgroup has been synthesized starting from linear fatty alcohols and has been characterized using spectroscopic techniques. The self-aggregation and thermodynamic properties of these surfactants have been investigated by pendant-drop surface tensiometry and conductivity measurements. The liquid crystalline behaviors of these surfactants were investigated by small-angle X-ray scattering (SAXS) technique. The quinuclidinolium headgroup demonstrated a unique ability to interlock among themselves thus affecting the physicochemical properties of surfactants in aqueous solution. The current research finding supports the new concept of headgroup interlocking which is supported by 1D and 2D NMR studies. PMID:25058797

  1. Coalescence during emulsification. 2. Role of small molecule surfactants.

    PubMed

    Lobo, Lloyd; Svereika, Aileen

    2003-05-15

    An oil-soluble hexadecyl pyrene (HDP) probe is used to monitor coalescence of hexadecane oil-in-water emulsions, during emulsification, in stirred systems and in a high-pressure homogenizer (microfluidizer), when small molecule surfactants are used as emulsifiers. The effect of sodium dodecyl sulfate concentration and salt concentration on the amount of coalescence and final drop size is studied. The behavior of oil-soluble surfactants and mixtures of oil-soluble and water-soluble surfactants on emulsification performance is also discussed. For high-pressure homogenizers, the drop sizes obtained are found to depend mostly on the ability of surfactants to stabilize the drops against coalescence, rather than their ability to reduce the interfacial tension. Increasing oil phase fractions increase the coalescence rate, because of the increase in collision frequency, which, in turn, impacts the drop size of the homogenized emulsion. PMID:16256561

  2. 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.

  3. 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

  4. 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

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

    NASA Astrophysics Data System (ADS)

    Ghadiali, Samir Nuruddin

    2000-10-01

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

  6. Chitosan macroporous foams obtained in highly concentrated emulsions as templates.

    PubMed

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

    2013-11-15

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

  7. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

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

    PubMed

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

    2009-08-01

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

  10. 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.

  11. 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

    2016-08-01

    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.

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

    PubMed

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

    2012-10-01

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

  13. 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

  14. 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

  15. 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

  16. Aggregation behavior of a tetrameric cationic surfactant in aqueous solution.

    PubMed

    Hou, Yanbo; Han, Yuchun; Deng, Manli; Xiang, Junfen; Wang, Yilin

    2010-01-01

    A star-shaped tetrameric quaternary ammonium surfactant PATC, which has four hydrophobic chains and charged hydrophilic headgroups connected by amide-type spacer group, has been synthesized in this work. Surface tension, electrical conductivity, ITC, DLS, and NMR have been used to investigate the relationship between its chemical structure and its aggregation properties. Interestingly, a large size distribution around 75 nm is observed below the critical micelle concentration (cmc) of PATC, and the large size distribution starts to decrease beyond the cmc and finally transfers to a small size distribution. It is proved that the large size premicellar aggregates may display network-like structure, and the size decrease beyond the cmc is the transition of the network-like aggregates to micelles. The possible reason is that intramolecular electrostatic repulsion among the charged headgroups below the cmc leads to a star-shaped molecular configuration, which may form the network-like aggregates through intermolecular hydrophobic interaction between hydrocarbon chains, while the hydrophobic effect becomes strong enough to turn the molecular configuration into pyramid-like shape beyond the cmc, which make the transition of network-like aggregates to micelles available. PMID:19947615

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

    PubMed

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

    2013-10-01

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

  18. Water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction for the determination of organochlorine pesticides in aqueous samples.

    PubMed

    Li, Yee; Chen, Pai-Shan; Huang, Shang-Da

    2013-07-26

    A novel sample preparation method, "water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction (WLSEME)", coupled with gas chromatography using an electron capture detector (GC-ECD) was developed for the analysis of the organochlorine pesticides (OCPs), heptachlor, α-endosulfan, 4,4-DDE, 2,4-DDD and endrin, in aqueous samples. A microsyringe is used to withdrew and discharge 10-12μL of the extraction solvent and 60-120μL of water as the dispersed solvent (containing 1mgL(-1), Tween 80) 4 times within 10s to form a cloudy emulsified solution in the syringe. This is then injected into an 8mL aqueous sample spiked with all above OCPs. Dodecyl acetate and 2-dodecanol were both selected as extraction solvents to optimize their conditions separately. The total extraction time was about 0.5min. Under optimum conditions, using dodecyl acetate (12μL) as extraction solvent, the linear range of the method was 10-1000ngL(-1) for all OCPs, and the the limits of detection (LODs) ranged from 1 to 5ngL(-1). The absolute recoveries and relative recoveries were from 20.8 to 43.5% and 83.2 to 109.8% for lake water, and 19.9-49.2% and 85.4-115.9% for seawater respectively. In the second method, 2-dodecanol as extraction solvent, the linear range was from 5 to 5000ngL(-1) for the target compounds, and the LODs were between 0.5 and 2ngL(-1). The absolute recoveries and relative recoveries ranged from 25.7 to 42.2% and 96.3-111.2% for sea water, and 22.4-41.9% and 90.7-107.9% for stream water. This could solve several problems, which commonly occur in ultrasound-assisted emulsification micro-extraction (USAEME), dispersive liquid-liquid micro-extraction (DLLME) and other assisted emulsification methods. These problems include analyte degradation, increased solubility of the extraction solvent and analyte, and high toxicity and large volume of the organic solvent used. PMID:23566919

  19. Rheology of emulsions.

    PubMed

    Derkach, Svetlana R

    2009-10-30

    The review is devoted to the historical and modern understanding of rheological properties of emulsions in a broad range of concentration. In the limiting case of dilute emulsions, the discussion is based on the analogy and differences in properties of suspensions and emulsions. For concentrated emulsions, the main peculiarities of their rheological behaviour are considered. Different approaches to understand the concentration dependencies of viscosity are presented and compared. The effects of non-Newtonian flow curves and the apparent transition to yielding with increasing concentration of the dispersed phase are discussed. The problem of droplet deformation in shear fields is touched. The highly concentrated emulsions (beyond the limit of closest packing of spherical particles) are treated as visco-plastic media, and the principle features of their rheology (elasticity, yielding, concentration and droplet size dependencies) are considered. A special attention is paid to the problem of shear stability of drops of an internal phase starting from the theory of the single drop behaviour, including approaches for the estimation of drops' stability in concentrated emulsions. Polymer blends are also treated as emulsions, though taking into account their peculiarities due to the coexistence of two interpenetrated phases. Different theoretical models of deformation of polymer drops were discussed bearing in mind the central goal of predictions of the visco-elastic properties of emulsions as functions of the properties of individual components and the interfacial layer. The role of surfactants is discussed from the point of view of stability of emulsions in time and their special influence on the rheology of emulsions. PMID:19683219

  20. 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

  1. 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

  2. Produced fluid emulsions. Final report

    SciTech Connect

    Hurley, C.F.; Himmelblau, A.; Trom, L.

    1984-09-01

    Emulsion production and stabilization may be due to one or more of several phenomenon including water-oil ratio, oil and brine chemistry, and surfactant and polymer type and concentration. They may influence emulsification either independently or with dependence on one or more of the other factors. Task One has tried to define which factors are dominant and what effect variations in them will have on the emulsion characteristics for each of the fields investigated. Emulsions were produced using a hand homogenizer at a fixed setting for a specific length of time to ensure all samples were produced uniformly. A du Nouy apparatus was used to measure surface and interfacial tensions and a binocular microscope was used in the micro-visual studies. The emulsions were treated in a similar manner with a wide variety of materials to not only break them, but also to help define which mechanisms are responsible for the stabilization of a particular emulsion. Core floods in Task Two utilized a six-foot sand-pack for a mixing medium. A six-inch long Berea core which followed, provided shear similar to that of the reservoir. The choice of oil, brine, surfactant and polymer were chosen to correlate to the Task One studies. Similarities and differences in the results between the bench-top and core flood studies are noted. The conditions of emulsion production and characteristics and the effectiveness of emulsion breakers are compared to help determine the mechanism of emulsion stabilization. 8 figures, 85 tables.

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

    SciTech Connect

    Li, X.; Lin, E.; Zhao, G.; Xiao, T.

    1996-12-01

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

  4. 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

  5. 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

  6. Deformation and stability of surfactant - or particle - laden drop

    NASA Astrophysics Data System (ADS)

    Brosseau, Quentin; Pradillo, Gerardo; Oberlander, Andrew; Vlahovska, Petia; SoftMech@Brown Team

    2015-11-01

    We present an experimental study of the behavior of a drop covered with insoluble surfactant or colloidal particles in a uniform DC electric field. Steady drop shapes, drop evolution upon application of the field, and drop relaxation after the field is turned off are observed for leaky dielectric fluids: Polybutadiene (PB), Silicon oil (PDMS), and Castor oil (CO). The surfactant is generated at the drop interface by reaction between end-functionalized PB and PDMS. The experimental data is compared with existing theoretical models for the steady shape of surfactant covered droplet, and adjusted models taking into account the presence of colloidal spheres with range of electrical properties. We will discuss the complex interplay of shape deformation, surfactant elasticity, particle redistribution, and interfacial charging in droplet electrohydrodynamics. Our results are important for understanding electrorheology of emulsions commonly found in the petroleum industry. We acknowledge grant NSF CBET 1437545 for funding.

  7. Interfacial Concentrations of Hydroxytyrosol and Its Lipophilic Esters in Intact Olive Oil-in-Water Emulsions: Effects of Antioxidant Hydrophobicity, Surfactant Concentration, and the Oil-to-Water Ratio on the Oxidative Stability of the Emulsions.

    PubMed

    Almeida, João; Losada-Barreiro, Sonia; Costa, Marlene; Paiva-Martins, Fátima; Bravo-Díaz, Carlos; Romsted, Laurence S

    2016-06-29

    We determined the interfacial molarities of the antioxidants, AOs, hydroxytyrosol (HT), and HT fatty acid esters with chain lengths of 1 to 16 carbons in intact olive oil/water/Tween 20 emulsions. The results were compared with chain length effects on the oxidative stability of the same emulsions, and a direct correlation was established. Both (AOI) molarities (varying 50-250 times greater than the stoichiometric 3.5 × 10(-3) M AO concentration) and antioxidant efficiencies show similar parabola-like dependences on AO chain length with a maximum at C8, consistent with the "cut-off" effect often observed at longer chain lengths. Results should aid in understanding the complex structure-reactivity relationships between AO efficiencies in emulsified systems and their hydrophobilic-hydrophobic balance. PMID:27157893

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

    PubMed

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

    2010-01-01

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

  9. 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

  10. Emulsion Inks for 3D Printing of High Porosity Materials.

    PubMed

    Sears, Nicholas A; Dhavalikar, Prachi S; Cosgriff-Hernandez, Elizabeth M

    2016-08-01

    Photocurable emulsion inks for use with solid freeform fabrication (SFF) to generate constructs with hierarchical porosity are presented. A high internal phase emulsion (HIPE) templating technique was utilized to prepare water-in-oil emulsions from a hydrophobic photopolymer, surfactant, and water. These HIPEs displayed strong shear thinning behavior that permitted layer-by-layer deposition into complex shapes and adequately high viscosity at low shear for shape retention after extrusion. Each layer was actively polymerized with an ultraviolet cure-on-dispense (CoD) technique and compositions with sufficient viscosity were able to produce tall, complex scaffolds with an internal lattice structure and microscale porosity. Evaluation of the rheological and cure properties indicated that the viscosity and cure rate both played an important role in print fidelity. These 3D printed polyHIPE constructs benefit from the tunable pore structure of emulsion templated material and the designed architecture of 3D printing. As such, these emulsion inks can be used to create ultra high porosity constructs with complex geometries and internal lattice structures not possible with traditional manufacturing techniques. PMID:27305061

  11. Surface active agent for emulsion fuel

    SciTech Connect

    Aoki, Y.; Furuyama, Y.; Moriyama, N.

    1980-01-08

    A method is claimed for preparing a water-in-oil emulsion fuel which comprises emulsifying water in oil, in the presence of an emulsifying agency. The improvement comprises using as the emulsifying agent, a surfactant. The formula of this surfactant is presented.

  12. Structures and Surface Properties of "Cyclic" Polyoxyethylene Alkyl Ethers: Unusual Behavior of Cyclic Surfactants in Water.

    PubMed

    Hirose, Yuki; Taira, Toshiaki; Sakai, Kenichi; Sakai, Hideki; Endo, Akira; Imura, Tomohiro

    2016-08-23

    The cyclization of amphiphiles has emerged as an attractive strategy for inducing remarkable properties in these materials without changing their chemical composition. In this study, we successfully synthesized three cyclic polyoxyethylene dodecyl ethers (c-POEC12's) with different ring sizes and explored the effects of their topology on their surface and self-assembly properties related to their function, comparing them with those of their linear counterparts (l-POEC12's). The surface activity of the c-POEC12's remained almost constant despite the change in their hydrophobic and hydrophilic balance (HLB) value, while that of the l-POEC12's decreased with an increase in the HLB value as general surfactants. In contrast to the normal micelles seen in the case of the l-POEC12's (3.4-9.7 nm), the cyclization of the POEC12's resulted in the formation of large spherical structures 72.8-256.8 nm in size. It also led to a dramatic decrease of 28 °C in the cloud point temperature. Furthermore, the cyclization of the POEC12's markedly suppressed the rate of protease hydrolysis caused by the surfactants. The initial rate of reduction of a detergent enzyme from Bacillus licheniformis was increased by more than 40% in the case of c-POE600C12 and c-POE1000C12, even though they exhibited surface activities almost equal to or higher than those of their linear counterparts. These results suggest that cyclization induces unusual aqueous behaviors in POEC12, making the surfactant milder with respect to detergent enzymes while ensuring it exhibits increased surface activity. PMID:27462805

  13. Understanding about How Different Foaming Gases Effect the Interfacial Array Behaviors of Surfactants and the Foam Properties.

    PubMed

    Sun, Yange; Qi, Xiaoqing; Sun, Haoyang; Zhao, Hui; Li, Ying

    2016-08-01

    In this paper, the detailed behaviors of all the molecules, especially the interfacial array behaviors of surfactants and diffusion behaviors of gas molecules, in foam systems with different gases (N2, O2, and CO2) being used as foaming agents were investigated by combining molecular dynamics simulation and experimental approaches for the purpose of interpreting how the molecular behaviors effect the properties of the foam and find out the key factors which fundamentally determine the foam stability. Sodium dodecyl sulfate SDS was used as the foam stabilizer. The foam decay and the drainage process were determined by Foamscan. A texture analyzer (TA) was utilized to measure the stiffness and viscoelasticity of the foam films. The experimental results agreed very well with the simulation results by which how the different gas components affect the interfacial behaviors of surfactant molecules and thereby bring influence on foam properties was described. PMID:27434752

  14. Extender components and surfactants affect boar sperm function and membrane behavior during cryopreservation.

    PubMed

    Pettitt, M J; Buhr, M M

    1998-01-01

    To determine how the individual components of extenders affected boar sperm function and membrane structure and to test a new surfactant's cryoprotective ability, boar sperm were cryopreserved in straws in BF5 extender plus or minus egg yolk plus or minus glycerol plus or minus a surfactant (Orvus ES Paste [OEP] or various concentrations of Pluronic F-127). After thawing, sperm function and fluidity of the isolated head plasma membrane (HPM) were determined. Total motility and adenosine triphosphate content (a measure of viability) were superior postthaw in sperm extended in egg yolk plus glycerol (P < 0.05); neither surfactant improved function. Egg yolk plus any other ingredients improved normal acrosome morphology, whereas a combined measure of motility and normal acrosome morphology was better in the presence of 0.33% OEP or 0.1% Pluronic F-127 (P < 0.05 vs. controls). Head plasma membrane was isolated from freshly collected spermatozoa and spermatozoa cryopreserved in the various extenders. Membrane fluidity was monitored with the probes cis-parinaric acid (cPNA), transparinaric acid (tPNA), and 1,6-diphenyl-1 ,3,5-hexatriene (DPH). The cPNA and the DPH monitor the fluidity of gel and liquid-crystalline areas of the membrane, whereas the tPNA preferentially monitors the gel-phase domains of the membrane. Additionally, DPH monitors the hydrophobic core of the bilayer. In the HPM from fresh sperm, the fluidity of each domain changed over time in a manner unique to that domain, and the behavior of the DPH domain varied among boars. The fluidity dynamics of each domain responded uniquely to cryopreservation. The cPNA domain was unaffected, the tPNA domain was altered by four of the eight extenders, and all extenders affected the fluidity of the DPH domain. Membrane structure was significantly correlated with cell function for sperm cryopreserved in extenders that preserved viability and motility. Sperm cryopreserved in egg yolk plus glycerol plus either OEP or 0

  15. Interfacial layers of complex-forming ionic surfactants with gelatin.

    PubMed

    Derkach, Svetlana R

    2015-08-01

    This review is devoted to discussing the results of studies of the influence of low-molecular weight surfactant additions on the composition and properties of gelatin adsorbed layers which are spontaneously created at water/air and water/non-polar-liquid interfaces. The interaction of surfactant with gelatin leads to the formation of complexes of variable content in the bulk of the aqueous phase. The composition content is determined by the component ratio and concentration of the added surfactant. The role of surfactants (anionic, cationic, non-ionic) capable of forming complexes with gelatin due to electrostatic and hydrophobic interactions is considered. Analysis of the interfacial layer properties is based on literature information, as well as the own author's data. These data include the results of measuring thermodynamic properties (interface tension), laws of formation (adsorption kinetics and thickness), and rheological properties of the layers, which are considered to be dependent on gelatin and surfactant concentration, pH, and temperature. The evolution of the interfacial layers' properties (with increasing surfactant concentration) is discussed in connection with the properties and content of gelatin-surfactant complexes appearing in the aqueous phase. Such an approach allows us to explain the main peculiarities of the layers' behavior including their stabilizing activity in relation to bilateral foam and emulsion films. PMID:24970019

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Effect of ionic surfactants on the phase behavior and structure of sucrose ester/water/oil systems.

    PubMed

    Rodríguez, Carlos; Acharya, Durga P; Hinata, Shigeki; Ishitobi, Masahiko; Kunieda, Hironobu

    2003-06-15

    The phase behavior and structure of sucrose ester/water/oil systems in the presence of long-chain cosurfactant (monolaurin) and small amounts of ionic surfactants was investigated by phase study and small angle X-ray scattering. In a water/sucrose ester/monolaurin/decane system at 27 degrees C, instead of a three-phase microemulsion, lamellar liquid crystals are formed in the dilute region. Unlike other systems in the presence of alcohol as cosurfactant, the HLB composition does not change with dilution, since monolaurin adsorbs almost completely in the interface. The addition of small amounts of ionic surfactant, regardless of the counterion, increases the solubilization of water in W/O microemulsions. The solubilization on oil in O/W microemulsions is not much affected, but structuring is induced and a viscous isotropic phase is formed. At high ionic surfactant concentrations, the single-phase microemulsion disappears and liquid crystals are favored. PMID:16256631

  1. Characteristics of Nano-emulsion for Cold Thermal Storage

    NASA Astrophysics Data System (ADS)

    Fumoto, Koji; Kawaji, Masahiro; Kawanami, Tsuyoshi

    Phase change emulsion (PCE) is novel kind of heat storage and heat transfer fluids. It has characteristics as follows; greater apparent specific heat and higher heat transfer abilities in the phase change temperature range than conventional single phase heat transfer fluid. In this paper, a phase change emulsion, which has droplet diameter distribution of nanometer, were prepared. The Nano-emulsion was formed by low energy emulsification methods, as known the phase inversion temperature (PIT) method. Physical properties, such as viscosity, diameter and its distribution of emulsion were investigated. Especially, the relationships between preparation method and the concentration of surfactant have been discussed in detail. The results show that the viscosity of the Nano-emulsion is lower than the micro-emulsion, which was made by same mixing ratio of surfactant and concentration of phase change material. In addition, the Nano-emulsion clarified that stability was higher than microemulsions.

  2. [Effect of surfactant on sorption behaviors of DDT on Jiaozhou Bay sediment].

    PubMed

    Cao, Xiao-Yan; Jing, Jian-Ning; Yang, Gui-Peng; Gong, Xiao-Fei

    2011-11-01

    A batch sorption study was carried out to investigate the sorption behaviors of DDT onto JiaoZhou Bay sediment in the presence of an anionic surfactant sodium dodecylbenzene sulfonate (SDBS), and a cationic surfactant, cetyltrimethylammonium bromide (CTAB) with low concentrations. The results indicated that the sorption process followed the pseudo-second-order model and the sorption systems could be well described by the Freundlich type. Within the investigated concentrations of CTAB and SDBS, both SDBS and CTAB increased the sorption of DDT to sediment. The sorption rate and capacity increased with increasing SDBS and CTAB concentrations, and CTAB showed a significant impact. Take p ,p'-DDT as an example, the sorption rate constant increased from 1.232 x 10(-2) g x (microg x min)(-1) to 4.193 x 10(-2) g x (microg x min)(-1) and the Freundlich coefficient increased from 2.866 (microg x g(-1)) (L x microg(-1))(1/n) to 7.932 (microg x g(-1)) (L x microg(-1))(1/n) when the SDBS concentration was 10 mg x L(-1). The influence of temperature on sorption of DDT in the presence of SDBS was also studied. Within the temperature range of 283-308 K, lower temperature had a positive effect on the sorption. The thermodynamic parameters showed that the sorption was spontaneous and exothermic, and the randomness was increased during the process. Furthermore, the presence of SDBS caused lower deltaG0, deltaH0 and deltaS0 values. This study provided theoretical foundation for migration, transformation and fate of DDT in Jiaozhou Bay sediment. PMID:22295631

  3. 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.

  4. 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.

  5. 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

  6. Effective short-range Coulomb correction to model the aggregation behavior of ionic surfactants

    NASA Astrophysics Data System (ADS)

    Burgos-Mármol, J. Javier; Solans, Conxita; Patti, Alessandro

    2016-06-01

    We present a short-range correction to the Coulomb potential to investigate the aggregation of amphiphilic molecules in aqueous solutions. The proposed modification allows to quantitatively reproduce the distribution of counterions above the critical micelle concentration (CMC) or, equivalently, the degree of ionization, α, of the micellar clusters. In particular, our theoretical framework has been applied to unveil the behavior of the cationic surfactant C24H49N2O2+ CH3SO4-, which offers a wide range of applications in the thriving and growing personal care market. A reliable and unambiguous estimation of α is essential to correctly understand many crucial features of the micellar solutions, such as their viscoelastic behavior and transport properties, in order to provide sound formulations for the above mentioned personal care solutions. We have validated our theory by performing extensive lattice Monte Carlo simulations, which show an excellent agreement with experimental observations. More specifically, our coarse-grained model is able to reproduce and predict the complex morphology of the micelles observed at equilibrium. Additionally, our simulation results disclose the existence of a transition from a monodisperse to a bidisperse size distribution of aggregates, unveiling the intriguing existence of a second CMC.

  7. Effective short-range Coulomb correction to model the aggregation behavior of ionic surfactants.

    PubMed

    Burgos-Mármol, J Javier; Solans, Conxita; Patti, Alessandro

    2016-06-21

    We present a short-range correction to the Coulomb potential to investigate the aggregation of amphiphilic molecules in aqueous solutions. The proposed modification allows to quantitatively reproduce the distribution of counterions above the critical micelle concentration (CMC) or, equivalently, the degree of ionization, α, of the micellar clusters. In particular, our theoretical framework has been applied to unveil the behavior of the cationic surfactant C24H49N2O2 (+) CH3SO4 (-), which offers a wide range of applications in the thriving and growing personal care market. A reliable and unambiguous estimation of α is essential to correctly understand many crucial features of the micellar solutions, such as their viscoelastic behavior and transport properties, in order to provide sound formulations for the above mentioned personal care solutions. We have validated our theory by performing extensive lattice Monte Carlo simulations, which show an excellent agreement with experimental observations. More specifically, our coarse-grained model is able to reproduce and predict the complex morphology of the micelles observed at equilibrium. Additionally, our simulation results disclose the existence of a transition from a monodisperse to a bidisperse size distribution of aggregates, unveiling the intriguing existence of a second CMC. PMID:27334191

  8. 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...

  9. Phase behavior and rheological analysis of reverse liquid crystals and W/I2 and W/H2 gel emulsions using an amphiphilic block copolymer.

    PubMed

    May, Anna; Aramaki, Kenji; Gutiérrez, José María

    2011-03-15

    This article reports the phase behavior determi-nation of a system forming reverse liquid crystals and the formation of novel disperse systems in the two-phase region. The studied system is formed by water, cyclohexane, and Pluronic L-121, an amphiphilic block copolymer considered of special interest due to its aggregation and structural properties. This system forms reverse cubic (I2) and reverse hexagonal (H2) phases at high polymer concentrations. These reverse phases are of particular interest since in the two-phase region, stable high internal phase reverse emulsions can be formed. The characterization of the I2 and H2 phases and of the derived gel emulsions was performed with small-angle X-ray scattering (SAXS) and rheometry, and the influence of temperature and water content was studied. The H2 phase experimented a thermal transition to an I2 phase when temperature was increased, which presented an Fd3m structure. All samples showed a strong shear thinning behavior from low shear rates. The elastic modulus (G') in the I2 phase was around 1 order of magnitude higher than in the H2 phase. G' was predominantly higher than the viscous modulus (G''). In the gel emulsions, G' was nearly frequency-independent, indicating their gel type nature. Contrarily to water-in-oil (W/O) normal emulsions, in W/I2 and W/H2 gel emulsions, G', the complex viscosity (|η*|), and the yield stress (τ0) decreased with increasing water content, since the highly viscous microstructure of the continuous phase was responsible for the high viscosity and elastic behavior of the emulsions, instead of the volume fraction of dispersed phase and droplet size. A rheological analysis, in which the cooperative flow theory, the soft glass rheology model, and the slip plane model were analyzed and compared, was performed to obtain one single model that could describe the non-Maxwellian behavior of both reverse phases and highly concentrated emulsions and to characterize their microstructure with

  10. 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

  11. 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.

  12. 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.

  13. Phase behavior of a mixture of poly(isoprene)-poly(oxyethylene) diblock copolymer and poly(oxyethylene) surfactant in water.

    PubMed

    Kunieda, Hironobu; Kaneko, Masaya; López-Quintela, M Arturo; Tsukahara, Masahiko

    2004-03-16

    The phase behavior of a mixture of poly(isoprene)-poly(oxyethylene) diblock copolymer (PI-PEO or C250EO70) and poly(oxyethylene) surfactant (C12EO3, C12EO5, C12EO6, C12EO7, and C12EO9) in water was investigated by phase study, small-angle X-ray scattering, and dynamic light scattering (DLS). The copolymer is not soluble in surfactant micellar cubic (I1), hexagonal (H1), and lamellar (Lalpha) liquid crystals, whereas an isotropic copolymer fluid phase coexists with these liquid crystals. Although the PI-PEO is relatively lipophilic, it increases the cloud temperatures of C12EO3-9 aqueous solutions at a relatively high PI-PEO content in the mixture. Most probably, in the copolymer-rich region, PI-PEO and C12EOn form a spherical composite micelle in which surfactant molecules are located at the interface and the PI chains form an oil pool inside. In the C12EO5/ and C12EO6/PI-PEO systems, one kind of micelles is produced in the wide range of mixing fraction, although macroscopic phase separation was observed within a few days after the sample preparation. On the other hand, small surfactant micelles coexist with copolymer giant micelles in C12EO7/ and C12EO9/PI-PEO aqueous solutions in the surfactant-rich region. The micellar shape and size are calculated using simple geometrical relations and compared with DLS data. Consequently, a large PI-PEO molecule is not soluble in surfactant bilayers (Lalpha phase), infinitely long rod micelles (H1 phase), and spherical micelles (I1 phase or hydrophilic spherical micelles) as a result of the packing constraint of the large PI chain. However, the copolymer is soluble in surfactant rod micelles (C12EO5 and C12EO6) because a rod-sphere transition of the surfactant micelles takes place and the long PI chains are incorporated inside the large spherical micelles. PMID:15835666

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

    PubMed

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

    2012-12-12

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

  15. Effect of Different Surfactants on the Interfacial Behavior of the n-Hexane-Water System in the Presence of Silica Nanoparticles.

    PubMed

    Biswal, Nihar Ranjan; Rangera, Naveen; Singh, Jayant K

    2016-07-28

    This paper presents the effect of negatively charged silica nanoparticles (NPs) on the interfacial tension of the n-hexane-water system at variable concentrations of four different surfactants, viz., an anionic surfactant, sodium dodecyl sulfate (SDS), a cationic surfactant, cetyltrimethylammonium bromide (CTAB), and two nonionic surfactants, Tween 20 and Triton X-100 (TX-100). The presence of negatively charged silica nanoparticles is found to have a different effect depending on the type of surfactant. In the case of ionic surfactants, SDS and CTAB, silica NPs reduce the interfacial tension of the system. On the contrary, for nonionic surfactants, Tween 20 and TX-100, silica NPs increase the interfacial tension. The increasing/decreasing nature of the interfacial tension in the presence of NPs is well supported by the calculated surface excess concentrations. The diffusion kinetic control (DKC) and statistical rate theory (SRT) models are used to understand the behavior of dynamic interfacial tension of the surfactant-NP-oil-water system. The DKC model is found to describe the studied surfactant-NP-oil-water systems more aptly. PMID:27367433

  16. Solution behavior and solid phase transitions of quaternary ammonium surfactants with head groups decorated by hydroxyl groups.

    PubMed

    Song, Binglei; Shang, Shibin; Song, Zhanqian

    2012-09-15

    Hydrogen bonds are strong intermolecular interactions, which are very important in molecular aggregation and new phase formation. Three long-chain quaternary ammonium surfactants, N,N-diethyl-N-(2-hydroxyethyl)-N-octadecylammonium bromide with one hydroxyl group, N-ethyl-N,N-bis (2-hydroxyethyl)-N-octadecylammonium bromide with two hydroxyl groups and N,N,N-tris (2-hydroxyethyl)-N-octadecylammonium bromide with three hydroxyl groups, abbreviated as SHQ, DHQ, and THQ, respectively, were synthesized in this work. Their solution behavior and solid phase transitions were investigated by surface tension, differential scanning calorimetry (DSC), X-ray diffraction (XRD), polarizing optical microscopy (POM), and Infrared (IR) spectroscopy. The hydrogen bonds introduced by the substituted hydroxyl groups promoted surfactant adsorption at the air/water interface and aggregation in solution. In the crystal state, an increased number of hydroxyl groups caused a larger tilt angle of the long axis of surfactant molecules with the layer normal. Above certain temperatures, SHQ and DHQ formed highly ordered smectic T and smectic A phases while THQ only formed less ordered smectic A phase. The weakened electrostatic attractions between opposite ions and the thicker polar sublayers of mesophases caused by the enhanced number of hydrogen bonds are responsible for the mesophase formation and transition of these surfactants. PMID:22762982

  17. 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

  18. 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.

  19. 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

  20. Polarization transfer solid-state NMR for studying surfactant phase behavior.

    PubMed

    Nowacka, Agnieszka; Mohr, Parveen Choudhary; Norrman, Jens; Martin, Rachel W; Topgaard, Daniel

    2010-11-16

    The phase behavior of amphiphiles, e.g., lipids and surfactants, at low water content is of great interest for many technical and pharmaceutical applications. When put in contact with air having a moderate relative humidity, amphiphiles often exhibit coexistence between solid and liquid crystalline phases, making their complete characterization difficult. This study describes a (13)C solid-state NMR technique for the investigation of amphiphile phase behavior in the water-poor regime. While the (13)C chemical shift is an indicator of molecular conformation, the (13)C signal intensities obtained with the CP and INEPT polarization transfer schemes yield information on molecular dynamics. A theoretical analysis incorporating the effect of molecular segment reorientation, with the correlation time τ(c) and order parameter S, shows that INEPT is most efficient for mobile segments with τ(c) < 0.01 μs and S < 0.05, while CP yields maximal signal for rigid segments with τ(c) > 10 μs and/or S > 0.5 under typical solid-state NMR experimental conditions. For liquid crystalline phases, where τ(c) < 0.01 μs and 0 < S < 0.3, the observed CP and INEPT intensities serve as a gauge of S. The combination of information on molecular conformation and dynamics permits facile phase diagram determination for systems with solid crystalline, solid amorphous, anisotropic liquid crystalline, and isotropic liquid (crystalline) phases as demonstrated by experiments on a series of reference systems with known phase structure. Three solid phases (anhydrous crystal, dihydrate, gel), two anisotropic liquid crystalline phases (normal hexagonal, lamellar), and two isotropic liquid crystalline phases (micellar cubic, bicontinuous cubic) are identified in the temperature-composition phase diagram of the cetyltrimethylammonium succinate/water system. Replacing the succinate counterion with DNA prevents the formation of phases other than hexagonal and leads to a general increase of τ(c). PMID

  1. Hybrid surfactants decorated with copper ions: aggregation behavior, antimicrobial activity and anti-proliferative effect.

    PubMed

    Kaur, Gurpreet; Kumar, Sandeep; Dilbaghi, Neeraj; Bhanjana, Gaurav; Guru, Santosh Kumar; Bhushan, Shashi; Jaglan, Sundeep; Hassan, P A; Aswal, V K

    2016-09-14

    In the present study, the emphasis is laid on the self aggregation behavior of copper based inorganic-organic hybrids in aqueous media. The two complexes, cationic hexadecyl pyridinium trichloro cuprate (1 : 1), [Cp](+)[CuCl3](-), and bishexadecylpyridinium tetrachloro cuprate (2 : 1), [Cp2](2+)[CuCl4](2-), were synthesized using the ligand insertion method. The complexes were characterized using elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and thermogravimetric analysis. The copper complexes were found to be thermally stable, and in the solid state, they possessed the perovskite arrangement with [Cp2](2+)[CuCl4](2-) exhibiting superior stability and crystallinity. The self aggregation behavior of the prepared complexes was analyzed in solution phase (in aqueous medium) using surface tension, conductivity, XRD and small angle neutron scattering (SANS). The results show that the presence of copper as a co-ion in both the stoichiometries results in lower critical micellization concentrations than their precursor. Micellization was thermodynamically spontaneous and micelles formed were ellipsoidal in shape and underwent a prolate ellipsoidal growth with an increase in the concentration of metallosurfactant, as estimated from the SANS. Furthermore, these metallosurfactants were investigated for biocompatibility (using hemolytic assay), antimicrobial activity (fungus and bacteria) and cytotoxicity using human cancerous cells. The hemolysis activity was found to depend on the aggregated state of the metallosurfactants, displaying the highest activity in the monomeric state, and the minimum for post micellar concentrations. The surfactants were found to enhance the antibacterial activity by twofold or more, with the addition of metal in both the stoichiometries. On the contrary, for anticancer and antifungal activities, barely any regular trend or generalization could be obtained

  2. 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

  3. Surfactant-Triggered Fluorescence Turn "on/off" Behavior of a Polythiophene-graft-Polyampholyte.

    PubMed

    Ghosh, Radhakanta; Das, Sandip; Chatterjee, Dhruba P; Nandi, Arun K

    2016-08-23

    Polythiophene-graft-polyampholyte (PTP) is synthesized using N,N-dimethylaminoethyl methacrylate and tert-butyl methacrylate monomers by grafting from polythiophene backbone, followed by hydrolysis. The resulting polymer exhibits aqueous solubility via formation of small-sized miceller aggregates with hydrophobic polythiophene at the center and radiating polyionic side chains (cationic or anionic depending on the pH of the medium) at the outer periphery. The critical micelle concentration of PTP in acidic solution (0.025 mg/mL, pH = 2.7) is determined from fluorescence spectroscopy. PTP exhibits reversible fluorescence on and off response in both acidic and basic medium with the sequential addition of differently charged ionic surfactants, repeatedly. The fluorescence intensity of PTP at pH 2.7 increases with the addition of an anionic surfactant, sodium dodecyl benzenesulfonate (SDBS), due to the self-aggregation forming compound micelles. The fluorescence intensity of these solutions again decreases on addition of a cationic surfactant, cetyltrimethylammonium bromide (CTAB), because of assembling of SDBS with CTAB, thus deassembling the PTP-SDBS aggregates. At pH 9.2, these turn on and turn off responses are also shown by PTP with the sequential addition of cationic surfactant (CTAB) and anionic surfactant (SDBS), respectively. This result shows that PTP has potential for surfactant-induced reversible fluorescence turn on and off using ionic surfactant (SDBS and CTAB) through self-assembling and deassembling of the ionic aggregates. The reversible aggregation and disaggregation process of PTP with the surfactants at both acidic and basic pH is supported from dynamic light scattering and Fourier transform infrared spectroscopy. The morphology of the above systems studied by transmission and scanning electron microscopy also supports the above aggregation and disaggregation process. PMID:27465928

  4. Separation of oil-in-water emulsions by microbubble treatment and the effect of adding coagulant or cationic surfactant on removal efficiency.

    PubMed

    Van Le, Tuan; Imai, Tsuyoshi; Higuchi, Takaya; Doi, Ryosuke; Teeka, Jantima; Xiaofeng, Sun; Teerakun, Mullika

    2012-01-01

    This study examined the efficiencies of microbubble (MB) treatment, MB treatment with polyaluminium chloride (PAC) as a coagulant, and MB treatment with cetyltrimethylammonium chloride (CTAC) as a cationic surfactant in the separation of emulsified oil (EO) by modified column flotation. Batch mode experiments were conducted by synthesizing emulsified palm oil (d<20 μm), and the chemical oxygen demand (COD) of the influent and effluent was measured to evaluate the treatment performance. MB treatment with PAC and MB treatment with CTAC were found to be more efficient in EO removal than the MB treatment alone. At an EO concentration of ∼1,000 mg L(-1) (pH 7) and under identical treatment conditions (MB generation time: 2.5 min, flotation time: 30 min), MB treatment with PAC (50 mg L(-1)) and that with CTAC (0.5 mg L(-1)) showed equally high EO removal efficiencies of 92 and 89%, respectively. This result is of significant relevance to studies focusing on the development of economical and high-efficiency flotation systems. Furthermore, the effect of pH was investigated by varying the sample pH from 3 to 8, which showed that the EO separation efficiency of MB alone increased drastically from slightly alkaline to acidic condition. PMID:22797232

  5. Encapsulating aspirin into a surfactant-free ethyl cellulose microsphere using non-toxic solvents by emulsion solvent-evaporation technique.

    PubMed

    Yang, C Y; Tsay, S Y; Tsiang, R C

    2001-01-01

    Microencapsulation of aspirin in ethylcellulose was studied in a surfactant-free, water-in-oil type of emulsification/solvent evaporation process using non-toxic solvents. Ethanol was used as the dispersed phase and soybean oil as the continuous phase. The recovered weight, particle size distribution, aspirin loading efficiency, and the aspirin release rate of microspheres were analysed. The addition of a small amount of non-solvent (water) prior to the emulsification was found to have a significant impact on the microencapsulation process. Adding non-solvent increases the recovered weight and the size of the microspheres. The addition of non-solvent also markedly changes the microsphere characteristics, resulting in a coarser surface and an increased release rate. Increasing the emulsification evaporation temperature increases the size of the microsphere, but reduces the recovered weight and loading efficiency. The release rate follows a first-order kinetics and Higuchi matrix kinetics at low concentrations of non-solvent, suggesting a monolithic system with aspirin uniformly distributed in the microsphere. PMID:11253939

  6. 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.

  7. 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.

  8. Demulsification of Redox-Active Emulsions by Chemical Oxidation.

    PubMed

    Takahashi, Yutaka; Koizumi, Nanami; Kondo, Yukishige

    2016-08-01

    This article reports the influence of redox reactions on emulsions of n-octane and an aqueous solution of a ferrocene-containing surfactant (FTMA; (11-ferrocenylundecyl)trimethylammonium bromide). Above a certain surfactant concentration, stable O/W emulsions were formed from an aqueous solution of reduced FTMA; in contrast, mixtures of n-octane and an aqueous solution of oxidized FTMA did not form emulsions at any surfactant concentration. Furthermore, adding an oxidant to the stable O/W emulsions of reduced FTMA led to coalescence of the oil (octane) droplets in the emulsions, and subsequently, the oil and water (aqueous FTMA solution) phases fully separated from the emulsions, i.e., demulsification occurred. Equilibrated interfacial tension measurements indicate that oxidation of the ferrocenyl group in FTMA brings about an increase in the interfacial tension between the octane and aqueous surfactant solution phases. From these results, we concluded that the oxidation of reduced FTMA to oxidized FTMA led to the desorption of surfactant molecules adsorbed at the interface of the octane/aqueous surfactant solution, leading to demulsification. PMID:27402350

  9. 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.

  10. 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

  11. 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...

  12. 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

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

    PubMed

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

    2015-07-14

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

  14. Spreading of Emulsions on Glass Substrates

    NASA Astrophysics Data System (ADS)

    Mohammad Karim, Alireza; Kavehpour, Pirouz

    2012-11-01

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

  15. 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.

  16. Dispersion behavior and aqueous foams in mixtures of a vesicle-forming surfactant and edible nanoparticles.

    PubMed

    Binks, Bernard P; Campbell, Shawn; Mashinchi, Saeed; Piatko, Michael P

    2015-03-17

    In an attempt to prepare ultrastable aqueous foams composed entirely of food-grade ingredients, we describe the foamability and foam stability of aqueous phases containing either calcium carbonate particles (CaCO3), sodium stearoyl lactylate surfactant (SSL), or their mixtures. Techniques including zeta potential measurements, adsorption isotherm determination, contact angles and optical and cryo-scanning electron microscopy are used to probe the interaction between particles and surfactant molecules. Aqueous dispersions of inherently hydrophilic cationic CaCO3 nanoparticles do not foam to any great extent. By contrast, aqueous dispersions of anionic SSL, which forms a lamellar phase/vesicles, foam progressively on increasing the concentration. Despite their foamability being low compared to that of micelle-forming surfactant sodium dodecyl sulfate, they are much more stable to collapse with half-lives (of up to 40 days) of around 2 orders of magnitude higher above the respective aggregation concentrations. We believe that, in addition to surfactant lamellae around bubbles, the bilayers within vesicles contain surfactant chains in a solidlike state yielding indestructible aggregates that jam the aqueous films between bubbles, reducing the drainage rate and both bubble coalescence and gas-transfer between bubbles. In mixtures of particles and surfactant, the adsorption of SSL monomers occurs on particle surfaces, leading to an increase in their hydrophobicity, promoting particle adsorption to bubble surfaces. Ultrastable foams result with half-lives of around an order of magnitude higher again at low concentrations and foams which lose only around 30% of their volume within a year at high concentrations. In the latter case, we evidence a high surface density of discrete surfactant-coated particles at bubble surfaces, rendering them stable to coalescence and disproportionation. PMID:25734773

  17. Polycyclic aromatic hydrocarbon behavior in bioactive soil slurry reactors amended with a nonionic surfactant.

    PubMed

    Kim, Han S; Weber, Walter J

    2005-02-01

    The effects of an ethoxylated sorbitan fatty ester nonionic surfactant (Tween 80) on the bioavailability of polycyclic aromatic hydrocarbons (PAHs) were examined by using soil-free and dense-slurry (67% solids content, by wt) systems containing a creosote-contaminated field soil. The dispersed-micelle-phase PAHs in soil-free systems were not readily bioavailable to the mixed consortium of microbes indigenous to the creosote-contaminated soil. Instead, the microbes partially and preferentially utilized readily available portions of the surfactant as carbon sources (16-18% of the initial surfactant dose). This selective microbial attack resulted in destabilization of dispersed-phase micelles and significant decreases in molar solubilization ratio and micelle-water partition coefficient values. Remarkably high dosages (>20 g/L) of Tween 80 were required to enhance mobilization of the sorbed PAHs via micelle association because of the sorption of Tween 80 to the soil employed. The PAHs released from the destabilized micelles in soil-slurry systems either associated with sorbed-phase surfactants or readsorbed to soil organic matter too rapidly to be biologically accessed, even by the acclimated PAH-degrading microbes present. The work provides important new information and practical insights to surfactant solubilization and mobilization technology applications for the bioremediation of PAH-contaminated soils and sediments. PMID:15719985

  18. 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

  19. Influence of methanol on the phase behavior of nonionic fluorinated surfactant: relation to the structure of mesoporous silica materials.

    PubMed

    Zimny, K; Blin, J L; Stébé, M J

    2009-02-15

    We have investigated the effect of methanol addition on the R(F)(8)(EO)(9) and R(F)(7)(EO)(8) surfactant-based systems. While upon the addition of methanol the L(1) micellar phase grows, the direct hexagonal (H(1)) and the lamellar (L(alpha)) liquid crystals progressively melt with the increase of alcohol content. Phase behavior and SAXS measurements proved that methanol molecules interact with the oxyethylene units of the surfactant. This involves a folding up of the hydrophobic chains in the liquid crystal phases. Moreover, for the R(F)(7)(EO)(8) surfactant, the cloud point curve is shifted to high temperatures upon addition of alcohol. Starting from these systems, we have prepared mesoporous materials. Results show that due to the hydrogen bonds between the alcohol and the EO groups, the hexagonal structure of the mesostructured silica obtained from R(F)(8)(EO)(9) is lost when the content of CH(3)OH is increased. In contrast, for the compounds prepared from the R(F)(7)(EO)(8)-based system, the pore ordering occurs in the presence of alcohol. This phenomenon has been related to the moving of the cloud point curve toward high temperatures with the addition of methanol. Our study reveals also that under our conditions the methanol released during the hydrolysis of the silica precursor does not affect the self-assembly mechanism in a positive or negative way. PMID:19058809

  20. 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

  1. 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

  2. A cationic azobenzene-surfactant-modified graphene hybrid: unique photoresponse and electrochemical behavior

    NASA Astrophysics Data System (ADS)

    Chen, Shu; Bao, Lin; Ou, Encai; Peng, Chang; Wang, Weimao; Xu, Weijian

    2015-11-01

    Surfactant-modified graphene hybrids containing azobenzene groups were for the first time prepared, and the electrochemical performance was investigated. The hybrids were obtained by electrostatic interactions between cationic azobenzene-surfactants and negatively charged graphene oxide in water. The electrostatic interactions, chemical structure and photoresponse of the hybrids were measured by using zeta potential values, fluorescence spectra, FTIR, XPS, XRD, SEM, UV-Vis absorption, AFM and Raman spectra. The electrochemical performance was estimated using cyclic voltammetry. The results show that strong electrostatic interactions exist between the azobenzene surfactants and graphene oxide. Notably, this azobenzene-graphene hybrid can self-assemble into aggregation structures in aqueous solution. Besides, the self-assembly can be reversibly controlled by ultraviolet light (365 nm) and blue light (455 nm) irradiation. This process is driven by the photoinduced polarity change of the cationic azobenzene surfactant and is responsible for the graphene hybrids' electrochemical performance. It is the first example of the reversible self-assembly of graphene driven by light irradiation.Surfactant-modified graphene hybrids containing azobenzene groups were for the first time prepared, and the electrochemical performance was investigated. The hybrids were obtained by electrostatic interactions between cationic azobenzene-surfactants and negatively charged graphene oxide in water. The electrostatic interactions, chemical structure and photoresponse of the hybrids were measured by using zeta potential values, fluorescence spectra, FTIR, XPS, XRD, SEM, UV-Vis absorption, AFM and Raman spectra. The electrochemical performance was estimated using cyclic voltammetry. The results show that strong electrostatic interactions exist between the azobenzene surfactants and graphene oxide. Notably, this azobenzene-graphene hybrid can self-assemble into aggregation structures in aqueous

  3. 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.

  4. 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.

  5. 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

  6. Influence of the Protein Particle Morphology and Partitioning on the Behavior of Particle-Stabilized Water-in-Water Emulsions.

    PubMed

    Gonzalez-Jordan, Alberto; Nicolai, Taco; Benyahia, Lazhar

    2016-07-19

    Protein fibrils, microgels, and fractal aggregates were produced by heating solutions of β-lactoglobulin (β-lg) under different conditions. The effect of the protein particle morphology on the stability and the structure of water-in-water (W/W) emulsions was studied for mixtures of poly(ethylene oxide) (PEO) and dextran. The protein particles partition to the dextran phase at pH 7.0 where they have a net negative charge, but they prefer the PEO phase at pH 3.0 where they have a net positive charge. The effect of partitioning on the stability and the structure of water-in-water (W/W) emulsions was studied by comparing emulsions at pH 3.0 with those at pH 7.0. The protein particle morphology and preference for one phase or the other are shown to have important consequences for the stability and the structure of the emulsions. Fibrils were found to be the most effective stabilizers at pH 7.0, whereas fractals were most effective at pH 3.0. The average droplet size obtained from confocal scanning laser microscopy was for most systems between 10 and 5 μm but was notably smaller for emulsions with fractals at pH 3.0. PMID:27333940

  7. A cationic azobenzene-surfactant-modified graphene hybrid: unique photoresponse and electrochemical behavior.

    PubMed

    Chen, Shu; Bao, Lin; Ou, Encai; Peng, Chang; Wang, Weimao; Xu, Weijian

    2015-12-14

    Surfactant-modified graphene hybrids containing azobenzene groups were for the first time prepared, and the electrochemical performance was investigated. The hybrids were obtained by electrostatic interactions between cationic azobenzene-surfactants and negatively charged graphene oxide in water. The electrostatic interactions, chemical structure and photoresponse of the hybrids were measured by using zeta potential values, fluorescence spectra, FTIR, XPS, XRD, SEM, UV-Vis absorption, AFM and Raman spectra. The electrochemical performance was estimated using cyclic voltammetry. The results show that strong electrostatic interactions exist between the azobenzene surfactants and graphene oxide. Notably, this azobenzene-graphene hybrid can self-assemble into aggregation structures in aqueous solution. Besides, the self-assembly can be reversibly controlled by ultraviolet light (365 nm) and blue light (455 nm) irradiation. This process is driven by the photoinduced polarity change of the cationic azobenzene surfactant and is responsible for the graphene hybrids' electrochemical performance. It is the first example of the reversible self-assembly of graphene driven by light irradiation. PMID:26553111

  8. Effect of the alkyl chains and of the headgroups on the thermal behavior of ascorbic acid surfactants mixtures.

    PubMed

    Venturini, Chiara; Pomposi, Cristina; Ambrosi, Moira; Carretti, Emiliano; Fratini, Emiliano; Lo Nostro, Pierandrea; Baglioni, Piero

    2014-03-20

    The role of the alkyl chain length and of the headgroup on the thermal behavior of mixtures of ASC8 (ascorbyl octanoate) and ASC16 (ascorbyl hexadecanoate) was investigated through differential scanning calorimetry, small- and wide-angle X-ray scattering, and Fourier transform infrared spectroscopy experiments. The formation of two eutectics and of a peritectic point was found from the phase diagram, and their structural properties were studied. The results were compared by investigating the thermal behavior of mixtures of octanoic acid and hexadecanoic acid. The findings provide insights into the role of the ascorbyl headgroups on the intermolecular interactions that determine the phase behavior of the two ascorbic acid based surfactants in the solid state. PMID:24555769

  9. Biophysical behavior of lung surfactant: implications for respiratory physiology and pathophysiology.

    PubMed

    Notter, R H

    1988-07-01

    The major emphasis of this article has been the complex, multicomponent system of surfactants that are required for proper pulmonary mechanics and function in the mammalian lung. Although LS was discovered over 30 years ago, and soon after was linked directly with neonatal RDS, it has taken a significant time for researchers to develop a fundamental understanding of the pulmonary surfactant system, and its actions and roles in respiratory physiology. Nonetheless, knowledge about LS has increased greatly over the past decade, and it is now clear that exogenous surfactant replacement therapy for infants with RDS provides a substantial clinical advantage for these patients. Indeed, the therapy is life-saving in many very small premature infants, and as experience accrues, and therapy is optimized, this advance is clearly a major step forward in neonatology. Perhaps the most prominent theme that has been presented throughout the discussion here is that pulmonary surfactant research must take advantage of interdisciplinary descriptions and cross-correlations for accurate and rapid progress. One positive feature of prior work on lung surfactant replacement and RDS is that its difficulty has forced investigators toward a level of understanding that is sound enough to extend LS research into related fields, such as lung injury and ARDS. These areas have their own complications, including a much more diverse pathology and injury progressions than found with neonatal RDS. In fact, if defining the role of lung surfactant in ARDS (and developing replacement therapy for it) had been the goal of investigators before considering neonatal RDS, it is difficult to imagine a positive outcome. The situation now, however, is one where it is realistic to think of recognizing when and how LS effects will occur in different ARDS lung injuries, so that surfactant replacement will have the best opportunity to help mitigate their progressive pathology. In dealing with ARDS, it is well to

  10. 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

  11. 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

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

    PubMed

    Perera, Ayomi S; Wang, Hongwang; Shrestha, Tej B; Troyer, Deryl L; Bossmann, Stefan H

    2013-01-01

    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

  13. 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

  14. 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.

  15. Thin liquid films from aqueous solutions of non-ionic polymeric surfactants.

    PubMed

    Exerowa, Dotchi; Platikanov, Dimo

    2009-01-01

    The conditions of formation and stability of foam, emulsion, and wetting films from aqueous solutions of non-ionic polymeric surfactants have been established. Two types of polymeric surfactants - PEO-PPO-PEO three-block copolymers (A-B-A type) and hydrophobically modified inulin graft polymer (AB(n) type) - have been explored. Information about surface forces and nanoscale phenomena in aqueous films containing polymeric surfactants was obtained using the micro-interferometric technique and the Thin Liquid Film-Pressure Balance Technique. Two types of surface forces, which determine the stability of the foam and emulsion films, have been distinguished, namely: DLVO-forces at low electrolyte concentrations and non-DLVO-forces at high electrolyte concentrations. Non-DLVO-forces are steric surface forces of the brush-to-brush and loop-to-loop interaction type according to De Gennes. A substantial difference in the behavior of these two film types has been established and in the case of O/W emulsion films transitions to Newton black film (NBF) have been observed. These films are very stable and so are the respective emulsions. In contrast the wetting films are relatively thicker compared to emulsion films, and their thickness depends on the concentration of the AB(n) polymeric surfactant. The steric repulsion of the loops and tails of the polymeric surfactant determine the film thickness of wetting films on a hydrophilic solid surface. For solid surfaces with different degrees of hydrophobicity the wetting films are stable only at high polymer concentrations and low degree of hydrophobicity. Otherwise the films are unstable and rupture. Two types of bilayer emulsion films have been distinguished for the first time. One type is related to the brush-to-brush or loop-to-loop interactions according to De Gennes. The other type is a NBF where the forces are also steric between strongly hydrated brush and loops but they are short-range forces acting in a two

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

    PubMed

    ElSayed, Eman M; Prasher, Shiv O

    2014-03-01

    Sorption/desorption of antibiotics, oxytetracycline (OTC), and sulfachloropyridazine (SCP) was investigated in the presence of a nonionic surfactant Brij35. Batch sorption experiments indicated that Freundlich equation fits sorption isotherms well for OTC. The sorption coefficients, KF, values were computed as 23.55 mL g(−1) in the absence of Brij35 and 25.46 mL g(−1) in the presence of Brij35 in the monomer form (below critical micelle concentration CMC, of 74 mg L(−1)). However, the KF values reduced to 12.76 mL g(−1) in the presence of Brij35 at 2.5 g L(−1). Therefore, irrigation with surfactant-rich water may increase the leaching potential of OTC. In the case of SCP, the KF value, in the absence of Brij35, was 19.95 mL g(−1). As a result of increasing the concentration of Brij35 to 0.25 g L(−1) (about 2.5 CMC), KF values first increased and reached a maximum value of 95.49 mL g(−1) and then reduced to 66.06 mL g(−1), at surfactant concentration of 5 g L(−1). Unlike OTC, the presence of surfactant in irrigation water is likely to decrease SCP leaching. In the case of OTC, hysteresis was found at Brij35 concentrations below CMC. However, OTC desorbed readily from soil (no hysteresis) at Brij35 concentrations above CMC. In the case of SCP, no hysteresis was found in the presence of the surfactant, both below and above CMC. Further, the obtained values of the efficiency coefficient (E), reveals that Brij35 had the potential to release more OTC from the soil (E > 1) as compared to SCP (E < 1). From these results, it can be concluded that regular use of manure on agricultural soils, especially in regions where poor quality irrigation water is used, can increase OTC contamination of water resources. PMID:24234758

  17. Double inversion of emulsions induced by salt concentration.

    PubMed

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

    2012-05-01

    The effects of salt on emulsions containing sorbitan oleate (Span 80) and Laponite particles were investigated. Surprisingly, a novel double phase inversion was induced by simply changing the salt concentration. At fixed concentration of Laponite particles in the aqueous phase and surfactant in paraffin oil, emulsions are oil in water (o/w) when the concentration of NaCl is lower than 5 mM. Emulsions of water in oil (w/o) are obtained when the NaCl concentration is between 5 and 20 mM. Then the emulsions invert to o/w when the salt concentration is higher than 50 mM. In this process, different emulsifiers dominate the composition of the interfacial layer, and the emulsion type is correspondingly controlled. When the salt concentration is low in the aqueous dispersion of Laponite, the particles are discrete and can move to the interface freely. Therefore, the emulsions are stabilized by particles and surfactant, and the type is o/w as particles are in domination. At intermediate salt concentrations, the aqueous dispersions of Laponite are gel-like, the viscosity is high, and the transition of the particles from the aqueous phase to the interface is inhibited. The emulsions are stabilized mainly by lipophilic surfactant, and w/o emulsions are obtained. For high salt concentration, flocculation occurs and the viscosity of the dispersion is reduced; thus, the adsorption of particles is promoted and the type of emulsions inverts to o/w. Laser-induced fluorescent confocal micrographs and cryo transmission electron microscopy clearly confirm the adsorption of Laponite particles on the surface of o/w emulsion droplets, whereas the accumulation of particles at the w/o emulsion droplet surfaces was not observed. This mechanism is also supported by the results of rheology and interfacial tension measurements. PMID:22475400

  18. 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

  19. Polymer-surfactant systems in bulk and at fluid interfaces.

    PubMed

    Guzmán, Eduardo; Llamas, Sara; Maestro, Armando; Fernández-Peña, Laura; Akanno, Andrew; Miller, Reinhard; Ortega, Francisco; Rubio, Ramón G

    2016-07-01

    The interest of polymer-surfactant systems has undergone a spectacular development in the last thirty years due to their complex behavior and their importance in different industrial sectors. The importance can be mainly associated with the rich phase behavior of these mixtures that confers a wide range of physico-chemical properties to the complexes formed by polymers and surfactants, both in bulk and at the interfaces. This latter aspect is especially relevant because of the use of their mixture for the stabilization of dispersed systems such as foams and emulsions, with an increasing interest in several fields such as cosmetic, food science or fabrication of controlled drug delivery structures. This review presents a comprehensive analysis of different aspects related to the phase behavior of these mixtures and their intriguing behavior after adsorption at the liquid/air interface. A discussion of some physical properties of the bulk is also included. The discussion clearly points out that much more work is needed for obtaining the necessary insights for designing polymer-surfactant mixtures for specific applications. PMID:26608684

  20. Coalescence avalanches in 2D emulsions: a stochastic approach

    NASA Astrophysics Data System (ADS)

    Masila, Danny Raj; Rengaswamy, Raghunathan

    2015-11-01

    One coalescence event in a 2D concentrated emulsion can trigger an avalanche resulting in the rapid destabilization of the drop-assembly. The sensitive dependence of this phenomenon on various factors that include surfactant concentration and viscosities of the fluid phases makes the avalanching problem appear probabilistic. We propose a stochastic framework- that utilizes a probability function to explain local coalescence events- to study the dynamics of the coalescence avalanches. A function that accounts for the local coalescence mechanism is used to fit the experimentally (from literature) measured probability data. A continuation parameter is introduced along with this function to account for the effect of system properties on the avalanche dynamics. Our analysis reveals that this behavior is a result of the inherent autocatalytic nature of the process. We discover that the avalanche dynamics shows critical behavior where two outcomes are favored: no avalanche and large avalanches that lead to destabilization. We study the effect of system size and fluid properties on the avalanche dynamics. A sharp transition from non-autocatalytic (stable emulsions) to autocatalytic (unstable) behavior is observed as parameters are varied.

  1. 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

  2. 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

  3. 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.

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

    PubMed

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

    2012-06-26

    We present a detailed study of a salt-free cationic/anionic (catanionic) surfactant system where a strongly alkaline cationic surfactant (tetradecyltrimethylammonium hydroxide, TTAOH) was mixed with a single-chain fluorocarbon acid (nonadecafluorodecanoic acid, NFDA) and a hyperbranched hydrocarbon acid [di-(2-ethylhexyl)phosphoric acid, DEHPA] in water. Typically the concentration of TTAOH is fixed while the total concentration and mixing molar ratio of NFDA and DEHPA is varied. In the absence of DEHPA and at a TTAOH concentration of 80 mmol·L(-1), an isotropic L(1) phase, an L(1)/L(α) two-phase region, and a single L(α) phase were observed successively with increasing mixing molar ratio of NFDA to TTAOH (n(NFDA)/n(TTAOH)). In the NFDA-rich region (n(NFDA)/n(TTAOH) > 1), a small amount of excess NFDA can be solubilized into the L(α) phase while a large excess of NFDA eventually leads to phase separation. When NFDA is replaced gradually by DEHPA, the mixed system of TTAOH/NFDA/DEHPA/H(2)O follows the same phase sequence as that of the TTAOH/NFDA/H(2)O system and the phase boundaries remain almost unchanged. However, the viscoelasticity of the samples in the single L(α) phase region becomes higher at the same total surfactant concentration as characterized by rheological measurements. Cryo-transmission electron microscopic (cryo-TEM) observations revealed a microstructural evolution from unilamellar vesicles to multilamellar ones and finally to gaint onions. The size of the vesicle and number of lamella can be controlled by adjusting the molar ratio of NFDA to DEHPA. The dynamic properties of the vesicular solutions have also been investigated. It is found that the yield stress and the storage modulus are time-dependent after a static mixing process between the two different types of vesicle solutions, indicating the occurrence of a dynamic fusion between the two types of vesicles. The microenvironmental changes induced by aggregate transitions were probed by

  5. 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

  6. 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

  7. Extraction of anionic dye from aqueous solutions by emulsion liquid membrane.

    PubMed

    Dâas, Attef; Hamdaoui, Oualid

    2010-06-15

    In this work, the extraction of Congo red (CR), an anionic disazo direct dye, from aqueous solutions by emulsion liquid membrane (ELM) was investigated. The important operational parameters governing emulsion stability and extraction behavior of dye were studied. The extraction of CR was influenced by a number of variables such as surfactant concentration, stirring speed, acid concentration in the feed solution and volume ratios of internal phase to organic phase and of emulsion to feed solution. Under most favorable conditions, practically all the CR molecules present in the feed phase were extracted even in the presence of salt (NaCl). At the optimum experimental conditions, total removal of antharaquinonic dye Acid Blue 25 was attained after only 10 min. Influence of sodium carbonate concentration as internal receiving phase on the stripping efficiency of CR was examined. The best sodium carbonate concentration in the internal phase that conducted to excellent stripping efficiency (>99%) and emulsion stability was 0.1N. The membrane recovery was total and the permeation of CR was not decreased up to seven runs. ELM process is a promising alternative to conventional methods and should increase awareness of the potential for recovery of anionic dyes. PMID:20211520

  8. Tailoring of the porous structure of soft emulsion-templated polymer materials.

    PubMed

    Kovalenko, Artem; Zimny, Kévin; Mascaro, Benoit; Brunet, Thomas; Mondain-Monval, Olivier

    2016-06-21

    This paper discusses the formation of soft porous materials obtained by the polymerization of inverse water-in-silicone (polydimethylsiloxane, PDMS) emulsions. We show that the initial state of the emulsion has a strong impact on the porous structure and properties of the final material. We show that using a surfactant with different solubilities in the emulsion continuous phase (PDMS), it is possible to tune the interaction between emulsion droplets, which leads to materials with either interconnected or isolated pores. These two systems present completely different behavior upon drying, which results in macroporous air-filled materials in the interconnected case and in a collapsed material with low porosity in the second case. Finally, we compare the mechanical and acoustical properties of these two types of bulk polymer monoliths. We also describe the formation of micrometric polymer particles (beads) in these two cases. We show that materials with an interconnected macroporous structure have low mechanical moduli and low sound speed, and are suitable for acoustic applications. The mechanical and acoustical properties of the materials with a collapsed porous structure are similar to those of non-porous silicone, which makes them acoustically inactive. PMID:27195990

  9. 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.

  10. 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

  11. Online monitoring of polymerization reactions in inverse emulsions.

    PubMed

    Alb, Alina M; Farinato, Ray; Calbick, Joe; Reed, Wayne F

    2006-01-17

    Automatic continuous online monitoring of polymerization reactions (ACOMP) was adapted to the monitoring of acrylamide polymerization in inverse emulsions. This is the first application of ACOMP to heterogeneous phase polymerization. The conversion and reduced viscosity were monitored by continuously inverting and diluting the emulsion phase using a small reactor sample stream and a breaker surfactant solution, followed by UV absorption and viscometric detection. This inversion into a stable portion of the polymer/surfactant phase diagram is accomplished in tens of seconds, yielding dilute solutions containing acrylamide (Aam), polyacrylamide (PA), oil droplets, and small quantities of surfactant, initiator and other debris, and low molecular weight compounds. After establishing the means of making ACOMP measurements, a first application of the method is made to resolving some of the kinetic issues involved in emulsion polymerization, including the evolution of molecular mass, and the simultaneous action of an "intrinsic" initiator and an added chemical initiator. PMID:16401138

  12. 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

  13. Physicochemical behavior of oil-in-water emulsions: influence of milk protein mixtures, glycerol ester mixtures and fat characteristics.

    PubMed

    Granger, C; Barey, P; Veschambre, P; Cansell, M

    2005-05-25

    Different emulsions based on two protein mixtures (skim milk powder (SMP) and functional dairy proteins (FDP)), two mono-di-glyceride mixtures (MDG) (saturated and partially unsaturated), three fats (hydrogenated and refined coconut oils and refined palm oil) were studied to investigate the interactions occurring between the oil phase, low molecular weight emulsifiers and proteins. Immediately following the emulsification process, high diameters of fat globules were obtained in FDP-based systems, relevant of an aggregation phenomenon. At this stage, the fat globule size characteristics were dependent on the emulsifier and fat types present in the formulation. In contrast, SMP-based emulsions were characterized by low proportions of aggregated particles regardless the formulations. Ageing (24 h at 4 degrees C) promoted disaggregation in FDP formulations, while SMP emulsions were well stabilized. Just after the homogenization step, less proteins were required to stabilize the globule interface in FDP systems as compared to SMP ones. Only with SMP, the amount of protein load at the fat globule surface was influenced by the oil nature and/or by the emulsifier type. A competitive adsorption of caseins, over whey proteins, was demonstrated in the case of FDP. The ageing period promoted a displacement of the proteins adsorbed at the oil droplet interface, suggesting a disruption of the interfacial protein interactions. This disruption was more marked with SMP than with FDP and, in both cases, was more or less influenced by the emulsifier and oil phase natures. The variations of the viscosity and rheological parameters (elastic and viscous moduli) were not dependent on one specific component of the formulation. PMID:15893224

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

    NASA Astrophysics Data System (ADS)

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

    2006-11-01

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

  15. 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

  16. 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

  17. CHARACTERISTICS OF SURFACTANTS IN TOXICITY IDENTIFICATION EVALUATIONS

    EPA Science Inventory

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

  18. 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

  19. Facile fabrication of diphenylalanine peptide hollow spheres using ultrasound-assisted emulsion templates.

    PubMed

    Li, Qi; Ma, Hongchao; Jia, Yi; Li, Junbai; Zhu, Baohua

    2015-04-28

    The controlled self-assembly of diphenylalanine (FF) into unilocular and multilocular hollow spheres was successfully achieved by an ultrasound-assisted emulsion droplet template method. This novel surfactant-free emulsion droplet template method is envisaged to be applicable to other biomolecules and materials. PMID:25812722

  20. 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

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

    PubMed

    Zhang, Jianling; Han, Buxing

    2013-02-19

    Surfactant assemblies have a wide range of applications in areas such as the chemical industry, material science, biology, and enhanced oil recovery. From both theoretical and practical perspectives, researchers have focused on tuning the aggregation behaviors of surfactants. Researchers commonly use solid and liquid compounds such as cosurfactants, acids, salts, and alcohols as stimuli for tuning the aggregation behaviors. However, these additives can present economic and environmental costs and can contaminate or modify the product. Therefore researchers would like to develop effective methods for tuning surfactant aggregation with easily removable, economical, and environmentally benign stimuli. Supercritical or compressed CO(2) is abundant, nontoxic, and nonflammable and can be recycled easily after use. Compressed CO(2) is quite soluble in many liquids, and the solubility depends on pressure and temperature. Therefore researchers can continuously influence the properties of liquid solvents by controlling the pressure or temperature of CO(2). In this Account, we briefly review our recent studies on tuning the aggregation behaviors of surfactants in different media using supercritical or compressed CO(2). Supercritical or compressed CO(2) serves as a versatile regulator of a variety of properties of surfactant assemblies. Using CO(2), we can switch the micellization of surfactants in water, adjust the properties of reverse micelles, enhance the stability of vesicles, and modify the switching transition between different surfactant assemblies. We can also tune the properties of emulsions, induce the formation of nanoemulsions, and construct novel microemulsions. With these CO(2)-responsive surfactant assemblies, we have synthesized functional materials, optimized chemical reaction conditions, and enhanced extraction and separation efficiencies. Compared with the conventional solid or liquid additives, CO(2) shows some obvious advantages as an agent for modifying

  2. Phase and sedimentation behavior of oil (octane) dispersions in the presence of model mineral aggregates.

    PubMed

    Gupta, Anju; Sender, Maximilian; Fields, Sarah; Bothun, Geoffrey D

    2014-10-15

    Adsorption of suspended particles to the interface of surfactant-dispersed oil droplets can alter emulsion phase and sedimentation behavior. This work examines the effects of model mineral aggregates (silica nanoparticle aggregates or SNAs) on the behavior of oil (octane)-water emulsions prepared using sodium bis(2-ethylhexyl) sulfosuccinate (DOSS). Experiments were conducted at different SNA hydrophobicities in deionized and synthetic seawater (SSW), and at 0.5mM and 2.5mM DOSS. SNAs were characterized by thermogravimetric analysis (TGA) and dynamic light scattering (DLS), and the emulsions were examined by optical and cryogenic scanning electron microscopy. In deionized water, oil-in-water emulsions were formed with DOSS and the SNAs did not adhere to the droplets or alter emulsion behavior. In SSW, water-in-oil emulsions were formed with DOSS and SNA-DOSS binding through cation bridging led to phase inversion to oil-in-water emulsions. Droplet oil-mineral aggregates (OMAs) were observed for hydrophilic SNAs, while hydrophobic SNAs yielded quickly sedimenting agglomerated OMAs. PMID:25172613

  3. 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

  4. 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

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

    PubMed

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

    2009-06-15

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

  6. 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

  7. Formation of flavor oil microemulsions, nanoemulsions and emulsions: influence of composition and preparation method.

    PubMed

    Rao, Jiajia; McClements, David Julian

    2011-05-11

    This study aimed to establish conditions where stable microemulsions, nanoemulsions or emulsions could be fabricated from a nonionic surfactant (Tween 80) and flavor oil (lemon oil). Different colloidal dispersions could be formed by simple heat treatment (90 °C, 30 min) depending on the surfactant-to-oil ratio (SOR): emulsions (r > 100 nm) at SOR < 1; nanoemulsions (r < 100 nm) at 1 < SOR < 2; microemulsions (r < 10 nm) at SOR > 2. Turbidity, electrical conductivity, shear rheology, and DSC measurements suggested there was a kinetic energy barrier in the oil-water-surfactant systems at ambient temperature that prevented them from forming metastable emulsion/nanoemulsion or thermodynamically stable microemulsion systems. High energy homogenization (high pressure or ultrasonic homogenizer) or low energy homogenization (heating) could be used to form emulsions or nanoemulsions at low or intermediate SOR values; whereas only heating was necessary to form stable microemulsions at high SOR values. PMID:21410259

  8. 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

  9. Silicone oil emulsions stabilized by polymers and solid particles.

    PubMed

    Kawaguchi, Masami

    2016-07-01

    Silicone oil emulsions stabilized by various emulsifiers such as polymers, solid particles alone, and solid particles with pre-adsorbed surfactants or polymers are reviewed, focusing on their emulsion stability and rheological properties as a function of the emulsifier concentration. An increase in the concentration of the emulsifier leads to a decrease in the droplet size and an increase in the emulsion stability, irrespective of the emulsifier. Moreover, the overlapping concentration of polymer can be regarded as a criterion for the preparation of emulsions using polymeric emulsifiers. Changes in the emulsion stability and rheological responses of the emulsions prepared by the solid particles with pre-adsorbed polymers are discussed in terms of the amounts of the emulsifiers adsorbed. For emulsions prepared from hydrophilic silica particles with pre-adsorbed polymers, a decrease in the droplet size of an order of magnitude can be controlled by an increase in the concentration of polymer, whereas hydrophilic silica particles alone cannot produce stable silicone oil emulsions. PMID:26170165

  10. Nonlinear Dynamic Characteristics of Oil-in-Water Emulsions

    NASA Astrophysics Data System (ADS)

    Yin, Zhaoqi; Han, Yunfeng; Ren, Yingyu; Yang, Qiuyi; Jin, Ningde

    2016-08-01

    In this article, the nonlinear dynamic characteristics of oil-in-water emulsions under the addition of surfactant were experimentally investigated. Firstly, based on the vertical upward oil-water two-phase flow experiment in 20 mm inner diameter (ID) testing pipe, dynamic response signals of oil-in-water emulsions were recorded using vertical multiple electrode array (VMEA) sensor. Afterwards, the recurrence plot (RP) algorithm and multi-scale weighted complexity entropy causality plane (MS-WCECP) were employed to analyse the nonlinear characteristics of the signals. The results show that the certainty is decreasing and the randomness is increasing with the increment of surfactant concentration. This article provides a novel method for revealing the nonlinear dynamic characteristics, complexity, and randomness of oil-in-water emulsions with experimental measurement signals.

  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. Controlling the fluorescence behavior of 1-pyrenesulfonate by cointercalation with a surfactant in a layered double hydroxide.

    PubMed

    Costa, Ana L; Gomes, Ana C; Pillinger, Martyn; Gonçalves, Isabel S; Seixas de Melo, J Sérgio

    2015-04-28

    Zn-Al layered double hydroxides (LDHs) containing solely 1-pyrenesulfonate (PS) or 1-heptanesulfonate (HS) anions, or a mixture of the two with HS/PS molar ratios ranging between ca. 7.5 and 82, were prepared by the direct synthesis method and characterized by powder X-ray diffraction, thermal and elemental analyses, scanning electron microscopy, and FT-IR, FT-Raman, and (13)C{(1)H} CP MAS NMR spectroscopies. Well-ordered intercalates were obtained with basal spacings of 18.8 Å for the LDH intercalated by PS and 19.2-19.4 Å for the other materials containing HS. The photophysics of the solids, as well as the PS probe dissolved in water and common organic solvents (aiming to compare the behavior of the "isolated" molecule with that in the solid), were investigated by steady-state and time-resolved fluorescence techniques. The fluorescence spectra of the solid samples display two bands with maxima at 376 and 495 nm. Depending on the HS/PS ratios, the band intensity ratio (obtained at 375 and 520 nm) changes, reflecting different contributions from monomer and dimer species. The decays collected at 375 nm are biexponentials with a major component (∼97% of the total fluorescence) of 105 ns for the highest HS/PS ratio, which further loses importance with an increase in the PS content. When the decays are collected at 480 and 520 nm, the fits are triexponentials with a major component varying from 108 to 124 ns, attributed to an excimer. Steady-state and time-resolved measurements with PS in solution (ethanol, methanol, DMF, DMSO, and water) were also measured, and a comparison of the vibronic I1/I3 ratio and lifetimes in water (65 ns) with those in the LDHs indicates that the PS probe in the cointercalated LDHs is surrounded by the HS surfactant. PMID:25848919

  13. Interfacial behavior and film patterning of redox-active cationic copper(II)-containing surfactants.

    PubMed

    Driscoll, Jeffery A; Allard, Marco M; Wu, Libo; Heeg, Mary Jane; da Rocha, Sandro R P; Verani, Cláudio N

    2008-01-01

    Herein, we describe the synthesis and characterization of a novel series of single-tail amphiphiles LPyCn (Py=pyridine, Cn=C18, C16, C14, C10) and their copper(II)-containing complexes, which are of relevance for patterned films. The N-(pyridine-2-ylmethyl)alkyl-1-amine ligands and their complexes [CuIICl2(LPyC18)] (1), [CuIICl2(LPyC16)] (2), [CuIICl2(LPyC14)] (3), [CuIIBr2(LPyC18)] (4), [CuIIBr2(LPyC16)] (5), and [CuIIBr2(LPyC10)] (6) were synthesized, isolated, and characterized by means of mass spectrometry, IR and NMR spectroscopies, and elemental analysis. Complexes 1, 2, 3, and 6 had their molecular structure solved by X-ray diffraction methods, which showed that the local geometry around the metal center is distorted square planar. With the aim of using these species as precursors for redox-responsive films, an assessment of their electrochemical properties involved cyclic voltammetry in different solvents, with different supporting electrolytes and scan rates. Density functional theory calculations of relevant species in bulk and at interfaces were used to evaluate their electronic structure and dipole moments. The morphology and order of the resulting films at the air/water interface were studied by isothermal compression and Brewster angle microscopy. Biphasic patterned Langmuir films were observed for all complexes except 3 and 6, and dependence on the chain length and the nature of the halogen coligand determine the characteristics of the isotherms and their intricate topology. Complexes 3 and 6, which have shorter chain lengths, failed to exhibit organization. These results exemplify the first comprehensive study of the behavior of single-tail metallosurfactants, which are likely to lead to high-end technological applications based on their patterned films. PMID:18792023

  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. Dehydration of oil waste emulsions by means of flocculants

    SciTech Connect

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

    1995-05-01

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

  16. Polymer/surfactant transport in micellar flooding

    SciTech Connect

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

    1981-10-01

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

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

    PubMed

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

    2015-03-01

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

  18. 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

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

    PubMed

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

    2011-06-01

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

  20. [Aggregation Behavior of Collagen-Based Surfactant Molecules in Aqueous Solutions Based on Synchronization Fluorescence Spectrum Technology].

    PubMed

    Li, Cong-hu; Tian, Zhen-hua; Liu, Wen-tao; Li, Guo-ying

    2016-01-01

    Due to the intrinsic fluorescence characteristic of tyrosine (Tyr) and phenylalanine (Phe), synchronization fluorescence spectrum technology which adopted the constant wavelength difference (Δλ = 15 nm) was selected to investigate the effects of collagen-based surfactant (CBS) concentration, pH, NaCt concentration and temperature on the aggregation state of CBS molecules in aqueous solutions. Meanwhile, temperature-dependent two-dimensional (2D) synchronization fluorescence correlation analyses was used to investigate the variation order of Tyr and Phe residues in CBS molecules with the change of temperature. The results showed that the characteristic absorption peaks located at 261 and 282 nm were attributed to Phe and Tyr, respectively. With the increase of CBS concentration, the amount of Phe and Tyr residues increased gradually which resulted in the increase of aggregate degree of CBS molecules and then led to the increase of fluorescence intensity. When the pH value (pH 5.0) of CBS solutions was close to the isoelectric point of CBS, the aggregate degree of CBS molecules increased due to the increase of the hydrophobic interaction and the formation ability of hydrogen bond. Additionally, with the increase of NaCl concentration, the repulsion force for inter/intra-molecules of CBS decreased, which helped to improve the aggregation behavior of CBS molecules. However, with the increase of temperature, the aggregation state of CBS was changed to be monomolecular state, and then resulted in the decrease of the fluorescence intensity gradually due to the quenching, the denaturation and the decrease of hydrogen bond formation ability. Furthermore, temperature-dependent 2D synchronization fluorescence correlation spectroscopy demonstrated that at lower temperature (10-40 degrees C), the aggregate state of CBS changed to be loose state and then Phe residues located in the inside of the aggregate varied before Tyr residues; while in the heating process of 45

  1. Stability of drug-carrier emulsions containing phosphatidylcholine mixtures.

    PubMed

    Trotta, Michele; Pattarino, Franco; Ignoni, Terenzio

    2002-03-01

    Lipid emulsion particles containing 10% of medium chain triglycerides were prepared using 2% w/w of a mixture 1:1 w/w of purified soya phosphatidylcholine and 2-hexanoyl phosphatidylcholine as emulsifier mixture, for use as drug carriers. The mean droplet sizes of emulsions, prepared using an Ultra Turrax or a high-pressure homogenizer, were about 288 and 158 nm, respectively, compared with 380 and 268 nm for emulsions containing lecithin, or 325 and 240 nm for those containing 6-phosphatidylcholine. The stability of the emulsions, determined by monitoring the decrease of a lipophilic marker at a specified level within the emulsion, and observing coalescence over time, was also greatly increased using the emulsifier mixture. The emulsion stability did not notably change in the presence of a model destabilizing drug, indomethacin. The use of a second hydrophilic surfactant to adjust the packing properties of the lecithin at the oil-water interface provided an increase in the stability of lipid emulsions, and this may be of importance in the formulation of drug delivery systems. PMID:11880004

  2. 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).

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

    SciTech Connect

    Wasan, D.T.

    1990-08-01

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

  4. Stabilization of Oil-in-Water Emulsions with Noninterfacially Adsorbed Particles.

    PubMed

    Pilapil, Brandy K; Jahandideh, Heidi; Bryant, Steven L; Trifkovic, Milana

    2016-07-19

    Classical (surfactant stabilized) and Pickering (particle stabilized) type emulsions have been widely studied to elucidate the mechanisms by which emulsion stabilization is achieved. In Pickering emulsions, a key defining factor is that the stabilizing particles reside at the liquid-liquid interface providing a mechanical barrier to droplet coalescence. This interfacial adsorption is achieved through the use of nanoparticles that are partially wet by both liquid phases, often through covalent surface modification of or surfactant adsorption to the nanoparticle surfaces. Herein, we demonstrate particle-induced stabilization of an oil-in-water emulsion with fully water wet nanoparticles (no interfacial adsorption) via synergistic interaction with low concentrations of surfactants. Laser scanning confocal microscopy analysis allows for unique and vital insights into the properties of these emulsions via both three-dimensional imaging and real-time monitoring of particle dynamics at the oil-water interface. Investigation of these "non-Pickering" particle stabilized emulsions suggests that the nonadsorbed particles impart stability to the emulsion primarily via entropic forces imparted by the accumulation of silica nanoparticles in the coherent phase between dispersed oil droplets. PMID:27351486

  5. Development and evaluation of emulsions from Carapa guianensis (Andiroba) oil.

    PubMed

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

    2010-09-01

    Carapa guianensis, a popular medicinal plant known as "Andiroba" in Brazil, has been used in traditional medicine as an insect repellent and anti-inflammatory product. Additionally, this seed oil has been reported in the literature as a repellent against Aedes aegypti. The aim of this work is to report on the emulsification of vegetable oils such as "Andiroba" oil by using a blend of nonionic surfactants (Span 80® and Tween 20®), using the critical hydrophilic-lipophilic balance (HLB) and pseudo-ternary diagram as tools to evaluate the system's stability. The emulsions were prepared by the inverse phase method. Several formulations were made according to a HLB spreadsheet design (from 4.3 to 16.7), and the products were stored at 25°C and 4°C. The emulsion stabilities were tested both long- and short-term, and the more stable one was used for the pseudo-ternary diagram study. The emulsions were successfully obtained by a couple of surfactants, and the HLB analysis showed that the required HLB of the oil was 16.7. To conclude, the pseudo-ternary diagram identified several characteristic regions such as emulsion, micro-emulsion, and separation of phases. PMID:20824515

  6. 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.

  7. Process for emulsion flooding of petroleum reservoirs

    SciTech Connect

    Lepper, U.

    1984-12-18

    A process for emulsion flooding of petroleum reservoirs comprising injecting a thermodynamically stable microemulsion consisting of oil, a non-ionic surfactant and water which optionally contains salts dissolved in any desired concentrations, into an injection well; driving injected microemulsion bank through the reservoir by means of water which likewise may contain salts dissolved in any desired concentrations. The microemulsion bank in contact with the water driving the bank forms an excess phase with a high water content, a low surfactant content and low oil content, and has such a viscosity sufficient to prevent the penetration of the subsequent water into the microemulsion bank which would cause a decrease of its flowability and its ability to displace oil.

  8. 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.

  9. Effect of polymer-surfactant association on colloidal force

    NASA Astrophysics Data System (ADS)

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

    2002-07-01

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

  10. 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.