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1

Electrokinetic Studies on Emulsions Stabilized by Ionic Surfactants: The Electroacoustophoretic Behavior and Estimation of Davies’ HLB Increments  

Microsoft Academic Search

Model oil-in-water emulsions were made. To stabilize these emulsions ionic surfactants were added. Their electrokinetic behavior was studied applying the electroacoustophoresis technique. The so-called electrokinetic sonic amplitude (ESA) was determined as a function of ionic strength, pH, and concentration and type of surfactant at ambient temperature and pressure. More than 30 different types of surfactant, mainly cationics, were included. Ionic

O Boen Ho

1998-01-01

2

Behavior of soybean oil-in-water emulsion stabilized by nonionic surfactant  

Microsoft Academic Search

A soybean oil-in-water emulsion was prepared using nonionic Tween series surfactants. The effects of temperature, hydrophilic–lipophilic balance (HLB) value of the surfactant, and surfactant-to-oil ratio on the size of emulsion drops were investigated with an acoustic and electroacoustic devices. In the case of Tween 85, the influence of pH and electrolyte on the ? potential of emulsion drops was examined.

Jyh-Ping Hsu; Anca Nacu

2003-01-01

3

Characterization of Surfactant Free Emulsions  

NASA Astrophysics Data System (ADS)

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

Brar, Ramaninder; Urquidi, Jacob

2012-10-01

4

Method for treating oil-water emulsions and recovering surfactants  

Microsoft Academic Search

A process is described for breaking an oil-water-surfactant emulsion comprising crude oil, brine and surfactant, the emulsion being produced from a reservoir having a known reservoir temperature and a known reservoir salinity and having as one component a microemulsion which exhibits non-classical phase behavior. The process consists of: (a) bringing the temperature of the produced emulsion to be within an

J. R. Bragg; W. W. Gale

1986-01-01

5

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

PubMed

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

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

2011-07-01

6

Method of extracting and reutilizing surfactants from emulsions  

SciTech Connect

The invention extracts surfactants from produced emulsions of oil, water and surfactants from enhanced oil recovery operations and concentrates the surfactants into an aqueous solution. The produced emulsion is mixed with an alkali metal chloride salt, and butanol or pentanol, and allowed to separate into two phases, an oleic phase and an aqueous phase. The oleic phase is then mixed with fresh water containing about 1% to about 10% by weight of isopropanol, ethanol or methanol, and the mixture is allowed to separate into at least two phases, a substantially water-free and surfactant-free crude oil phase and an aqueous phase containing virtually all of the enhanced oil recovery surfactants originally within the produced emulsion. The surfactants in the aqueous phase may be reutilized for further enhanced oil recovery operations.

Ashwari, S. S.; Prukop, G.

1985-12-17

7

Crude oil emulsions containing a compatible fluorochemical surfactant  

SciTech Connect

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

Karydas, A.; Rodgers, J.

1991-02-19

8

Dynamics of a surfactant-covered drop and the non-Newtonian rheology of emulsions  

NASA Astrophysics Data System (ADS)

Complex fluids exhibit rich dynamic macroscopic behavior that stems from relaxation of the material microstructure. Emulsions are examples of complex fluids with drop-like morphology. Predicting the rheology of emulsions relies on a detailed understanding of the drop-level microhydrodynamics. The focus of this talk is on the dynamics of a drop in linear viscous flows. The drop is covered with a dilute monolayer of insoluble surfactant. The problem is challenging because of the nonlinear coupling of drop deformation, surface tension gradients, and bulk flows. The dynamics depends on the relative strength of various relaxation mechanisms that oppose the distortion of surfactant distribution and drop shape induced by the straining component of the flow. These restoring mechanisms include both Marangoni-- and shape-- relaxation, and drop rotation by the imposed flow. The evolution of the system was described by a nonlinear matrix equation formulation derived by expanding the fluid velocity, surfactant distribution and drop shape in spherical harmonics. We developed analytical expansions applicable where the surfactant distribution and drop shape are only slightly perturbed. Numerical results, including three-dimensional boundary integral simulations were used to determine the range of convergence for the expansions. Calculations of the stress in a dilute emulsion of surfactant-covered drops revealed that the interplay between different microstructural relaxation mechanisms gives rise to a rich non-Newtonian rheological behavior.

Vlahovska, Petia; Blawzdziewicz, Jerzy; Loewenberg, Michael

2004-03-01

9

Optimum phase-behavior formulation of surfactant/oil/water systems for the determination of chromium in heavy crude oil and in bitumen-in-water emulsion.  

PubMed

An "oil in water" formulation was optimized to determine chromium in heavy crude oil (HCO) and bitumen-in-water emulsion (Orimulsion-400(R)) samples by transversally heated electrothermal atomic absorption spectrometry (TH-ET AAS) using Zeeman effect background correction. The optimum proportion of the oil-water mixture ratio was 7:3 v/v (70 ml of oil as the internal phase) with a non-ionic surfactant concentration (Intan-100) in the emulsion of 0.2% w/w. Chromium was determined in different crude oil samples after dilution of the emulsions 1:9 v/v with a 0.2% w/w solution of surfactant in order to further reduce the viscosity from 100 to 1.6 cP and at the same time to bring the concentration of chromium within the working range of the ET AAS technique. The calibration graph was linear from 1.7 to 100 mug Cr l(-1). The sensitivity was of 0.0069 s l mug(-1), the characteristic mass (m(o)) was of 5.7 pg per 0.0044 s and the detection limit (3sigma) was of 0.52 mug l(-1). The relative standard deviation of the method, evaluated by replicate analyses of three crude oil samples varied in all cases between 1.5 and 2.6%. Recovery studies were performed on four Venezuelan crude oils, and the average chromium recovery values varied between 95.9-104.8, 90.6-107.6, 95.6-104.0 and 98.8-103.9% for the Cerro Negro, Crudo Hamaca and Boscán crude oils and for the Orimulsión(R)-400, respectively. The results obtained in this work for the Cerro Negro, Crudo Hamaca and Boscán crude oils and for the Orimulsión(R)-400 following the proposed procedure were of 0.448+/-0.008, 0.338+/-0.004 0.524+/-0.021 and 0.174+/-0.008 mg Cr l(-1), respectively, which were in good agreement with the values obtained by a tedious recommended standard procedure (respectively: 0.470+/-0.05, 0.335+/-0.080, 0.570+/-0.021 and 0.173+/-0.009 mg Cr l(-1)). PMID:18969194

Burguera, José L; Avila-Gómez, Rita M; Burguera, Marcela; Antón de Salager, Raquel; Salager, Jean-Louis; Bracho, Carlos L; Burguera-Pascu, Margarita; Burguera-Pascu, Constantin; Brunetto, Rosario; Gallignani, Máximo; Petit de Peña, Yaneita

2003-11-01

10

Pressure induced surfactant recovery during ultrafiltration of water-oil emulsions  

SciTech Connect

This patent describes a method for recovering surfactant from an oil/water/surfactant emulsion. The method consists of contacting the emulsion with an ultrafiltration membrane having a molecular weight cut-off in the range 30,000 to 500,000 at a pressure in the range 50 to 150 psi thereby selectively permeating the surfactant through the membrane.

Sweet, J.R.

1990-01-09

11

Vacuum evaporation of surfactant solutions and oil-in-water emulsions  

Microsoft Academic Search

Vacuum evaporation of surfactant solutions and oil-in-water (O\\/W) emulsions at laboratory-scale set-up was investigated. Experiments were performed with surfactant solutions and model emulsions formulated with a base oil (85–15% (w\\/w) mixture of a synthetic poly-?-olefin and a trimethylol propane trioleate ester, respectively) and the following surfactants: Brij-76 (polyethylene glycol octadecyl ether, non-ionic), CTAB (hexadecyltrimethyl ammonium bromide, cationic), or Oleth-10 (glycolic

Gemma Gutiérrez; José M. Benito; José Coca; Carmen Pazos

2010-01-01

12

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

PubMed

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

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

2010-04-01

13

Stability of high internal phase emulsions with sole cationic surfactant and its tailoring morphology of porous polymers based on the emulsions  

Microsoft Academic Search

Stable w\\/o high internal phase emulsion (HIPE) using cetyltrimethylammonium bromide (CTAB) as the sole surfactant was prepared with long time further mixing of the emulsion after the addition of aqueous phase was completed, although it was generally considered the emulsion would be unstable according to Bancroft rule. The delta backscattering data of these emulsions showed that the further mixing enhanced

Shengmiao Zhang; Jianding Chen; V. Tamara Perchyonok

2009-01-01

14

Effect of some cationic surfactants on an oil\\/water emulsion stabilized by dodecyl benzene sulphonate  

Microsoft Academic Search

The effect of some cationic surfactants on the stability of the xylene-in-water emulsion stabilized by dodecyl benzene sulphonate\\u000a has been studied. The globules size was determined microphotographically. The stability of the emulsion system has been assessed\\u000a by the measurement of electrokinetic potentials in presence of surfactants. The interaction energies have also been calculated\\u000a and plotted as a function of interparticle

M. K. Sharma; G. Chandra; S. K. Jha; S. N. Srivastava

15

Emulsions and equilibrium phase behaviour in silicone oil + water + nonionic surfactant mixtures  

Microsoft Academic Search

We have investigated several aspects of the emulsion and equilibrium phase behaviour of mixtures of water, nonionic surfactant (CnEm) and silicone oil (PDMS). Emulsions may be inverted from oil-in-water to water-in-oil on increasing the temperature or the concentration of NaCl electrolyte. The apparent phase inversion temperature (PIT) increases with an increase in the number of oxyethylene groups in the surfactant

B. P. Binks; J. Dong

1998-01-01

16

Interfacial properties of emulsions stabilized with surfactant and nonsurfactant coated boehmite nanoparticles.  

PubMed

The properties of emulsions stabilized with surface-modified boehmite particles of 26 and 8 nm in diameter have been investigated. The surface-modified particles were prepared by mixing aqueous dispersions of cationic boehmite particles with aqueous solutions of the surfactant p-dodecylbenzenesulfonic acid (DBSA) or the nonsurfactant p-toluenesulfonic acid (TSA). For the 26 nm particles, interfacial tension measurements indicate that p-dodecylbenzenesulfonic acid partitions between the particle surface and the oil-water interface, while p-toluenesulfonic acid remains on the particle surface. The partitioning of p-dodecylbenzenesulfonic acid supports the formation of emulsions, although in the absence of the particles the same surfactant concentration is not sufficient for emulsion stabilization. Due to the fast exchange kinetics, p-dodecylbenzenesulfonic acid is gradually replaced by particles. At equilibrium, the interfacial tension in the presence of the surface-modified particles is between the values for the pure particles and the pure surfactant solutions. However, the interfacial tension is independent of the surfactant concentration used in the preparation of the particles. Reducing the particle size to 8 nm leads to increased emulsion stability, and thus, the minimum particle concentration required to prepare stable emulsions was reduced to 0.1 g/L. However, above approximately 3.5 mmol/L of the sulfonic acids, the small particles dissolve slowly, and the emulsion stability is lost. This mechanism can be used to trigger the collapse of the emulsions. PMID:21028858

Tigges, Britta; Dederichs, Thomas; Möller, Martin; Liu, Tingting; Richtering, Walter; Weichold, Oliver

2010-12-01

17

Response of Surfactant Stabilized Oil-in-Water Emulsions to the Addition of Particles in an Aqueous Suspension.  

PubMed

As a model for understanding how surfactant-stabilized emulsions respond to the addition of interacting and noninteracting particles, we investigated the response of dodecane-in-water emulsions stabilized by SDS (anionic), CTAB (cationic), and Triton X-100 (nonionic) surfactants to the addition of an aqueous suspension of negatively charged fumed silica particles. The stability of the emulsion droplets and the concentration of surfactants/particles at the oil-water interfaces are sensitive to surfactant-particle interactions, mixing conditions, and the particle concentration in the bulk. Addition of the particle suspension to the SDS-stabilized emulsions showed no effect on emulsion stability. Coarsening of emulsion droplets is observed when fumed silica particles were added to emulsions stabilized by Triton X-100. Depending on the concentration of silica particles in the suspension, the addition of fumed silica particles to CTAB-stabilized emulsions resulted in droplet coalescence and phase separation of oil and water or formation of particle-coated droplets. Vigorous (vortex) mixing allows the particles to breach the oil-water interfaces and stabilize emulsions. While we have examined a specific particle suspension and a set of three surfactants, these observations can be generalized for other surfactant-particle mixtures. PMID:25312030

Katepalli, Hari; Bose, Arijit

2014-11-01

18

Influence of surfactant hydrophilicity on the formation of transparent O/I(1)-type emulsions.  

PubMed

The transparency of oil in cubic (O/I(1)) emulsions formed in water/C(12)EO(n)/isododecane systems (n=7, 9) with glycerol was investigated in order to understand the relation between surfactant hydrophilicity and transparency of the emulsion. In the C(12)EO(7) system, O/I(1) emulsions prepared in the I(1)+O region are milky when glycerol is not added. However, in the presence of glycerol, transparency increases with an increasing amount of glycerol because glycerol increases the refractive index of the I(1) phase until it gradually approaches that of the oil phase. However, a phase transition to the hexagonal phase takes place before the refractive indices match; therefore, a transparent emulsion is not obtained. On the other hand, in the C(12)EO(9) system, a transparent emulsion was prepared by adding glycerol because the refractive index of the I(1) phase matches that of the oil before the phase transition. Since long EO chains are required to maintain the large curvature of the I(1) phase against the addition of glycerol, a highly hydrophilic surfactant is required for the preparation of transparent emulsions. We also found that the viscosity of the O/I(1) emulsion decreases with the decreased viscosity of the I(1) phase obtained by adding glycerol. The low viscosity of the I(1) phase in the presence of glycerol could be related to an increase in the maximum oil solubilization into the I(1) phase. PMID:21768741

Takahashi, Takuya; Sugiyama, Yuki; Watanabe, Kei; Aramaki, Kenji

2011-01-01

19

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

PubMed Central

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

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

2009-01-01

20

Structure of high internal phase aqueous-in-oil emulsions and related inverse micelle solutions. 3. Variation of surfactant.  

PubMed

The small angle neutron scattering from high internal phase water-in-hexadecane and saturated ammonium nitrate-in-hexadecane emulsions is compared with that from related hexadecane-based inverse micellar solutions. Three molecular weights of the monodisperse polyisobutylene acid amide (PIBSA) surfactant 750, 1200, and 1700 were studied over a range of surfactant concentrations. As an additional comparison, emulsions based on sorbitan monooleate and isostearate surfactants were investigated. The scattering from molecular weight 1200 water-based PIBSA emulsions can be fitted at all concentrations to a model with a surfactant coated aqueous droplet-oil interface together with the majority of the surfactant in the oil phase of the emulsion in the form of inverse micelles. Variation of the molecular weight shows a variety of phases of increasing curvature: lamellar, sponge, and, most commonly, the emulsion structure described above. In addition, the molecular weight affects the oil component in the emulsions, which can contain either cylindrical micelles or spherical micelles of varying water but constant hexadecane content. Increased phase curvature is favored by both increased PIBSA molecular weight and ammonium nitrate dissolved in the water. These observations are consistent with "Wedge theory". The structures observed in the emulsions are close to those observed in related inverse micellar solutions made from hexadecane, the surfactant, and water. Lower concentrations of surfactant in the micellar solutions decrease micelle curvature, except where the inverse micelles are spherical and small; here, there is little effect of dilution. Substitution of sorbitan surfactants for PIBSAs produces slightly less organized but similar structures, with smaller spherical micelles containing proportionally more water. The aqueous-oil droplet interface has a relatively invariant monolayer of adsorbed surfactant. For all emulsions, we can infer from the mass balance that micelle concentrations are depressed in the inverse micellar solutions because up to half the added surfactant is present as individually dissolved molecules. PMID:19681586

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

2009-09-10

21

Rheological Measurements and Thermal Characterization of Lamellar Gel Phase Emulsions Developed with Cetearyl Alcohol\\/ Nonionic Ethoxylated Surfactants  

Microsoft Academic Search

The aim was to characterize emulsion systems (ES) containing nonionic ethoxylated surfactants by using rheological, microscopic and thermogravimetric assays. Three formulations were developed: ES-1: 8.0% (w\\/w) oleth-20; ES-2: 4.0% (w\\/w) oleth-20\\/4.0% (w\\/w) steareth-21; and ES-3: 8.0% (w\\/w) steareth-21. The systems showed typical non-Newtonian pseudoplastic behavior. The presence of lamellar gel phase was observed for all systems, being more pronounced for

Paula S. Prestes; Fabiana A. S. M. Soares; Adriano M. Oliveira; Elizabeth P. G. Arêas; Luiz A. Gioielli; Telma M. Kaneko; Kléber L. Guimarães; Maria Helena A. Zanin; Maria Valéria R. Velasco; André R. Baby

2012-01-01

22

Influence of pH on the stability of oil-in-water emulsions stabilized by a splittable surfactant  

Microsoft Academic Search

A laboratory study was conducted to evaluate the effect of pH on the stability of oil-in-water emulsions stabilized by a commercial splittable surfactant Triton SP-190 by comparison with the results obtained by a common surfactant Triton X-100. The emulsion stability was explored by measuring the volume of oil phase separated and the size of the dispersed droplets. It was found

Chin-Ming Chen; Chun-Hsiung Lu; Chien-Hsiang Chang; Yu-Min Yang; Jer-Ru Maa

2000-01-01

23

P450cam biocatalysis in surfactant-stabilized two-phase emulsions.  

PubMed

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-stabilized two-phase emulsion is a promising reaction medium for practical P450 biocatalysis, although its effectiveness for a given P450/substrate combination can depend on several factors, including competitive or sequential reactions, product inhibition, and NAD(P)H uncoupling. PMID:18098319

Ryan, Jessica D; Clark, Douglas S

2008-04-15

24

A Novel Algorithm for the Estimation of the Surfactant Surface Excess at Emulsion Interfaces  

E-print Network

When the theoretical values of the interfacial tension -resulting from the homogeneous distribution of ionic surfactant molecules amongst the interface of emulsion drops- are plotted against the total surfactant concentration, they produce a curve comparable to the Gibbs adsorption isotherm. However, the actual isotherm takes into account the solubility of the surfactant in the aqueous bulk phase. Hence, assuming that the total surfactant population is only distributed among the available oil/water interfaces, one can calculate what surface concentration is necessary to reproduce the experimental values of the interfacial tension. A similar procedure can be followed using the zeta potential of the drops as a standard for a given set of salt and surfactant concentrations. We applied these procedures to the case of hexadecane/water nanoemulsions at different salt concentrations. This information was used to compute typical interaction potentials between non-deformable nanoemulsion drops. The results indicate that there are significant differences between the surfactant population expected from macroscopic adsorption isotherms, and the actual surfactant popula- tion adsorbed to the surface of nanoemulsion drops.

German Urbina-Villalba; Sabrina Di Scipio; Neyda Garcia-Valera

2014-01-06

25

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

NASA Astrophysics Data System (ADS)

We show that excess surfactant, or salt, in the bulk phase of an oil in water ionic emulsion has strong consequences on the thermodynamical behavior of the dispersion. Static light scattering experiments have been performed to investigate the attractive interaction induced by micelles according to a depletion mechanism. This interaction can be largely reduced by adding salt. This depletion interaction leads to a phase transition which is characterized as a fluid-solid transition. The long range ordering of the droplets dense phase is characterized by visible light diffraction. The experimental phase diagram is quantitatively analysed as a transition between a perfect gaz and a harmonic solid. An analytical model is worked out from which we analyze the general phase diagram in terms of the volume fraction of the droplets, of the depth of their interaction potential and of the ratio (?/?), where ? is the range of the interaction and ? the droplet diameter. Cuts of the phase diagram at constant (?/?) feature a liquid-gas or a liquid-solid transition.

Bibette, J.; Roux, D.; Pouligny, B.

1992-03-01

26

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

PubMed

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

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

2012-11-15

27

Direct visualization of "coagulative nucleation" in surfactant-free emulsion polymerization.  

PubMed

It is generally believed that surfactant-free emulsion polymerization involves four steps: initiation, nucleation into primary particles, coagulation into secondary particles, and growth. By high resolution SEM-imaging of the intermediate polymerization products, the evolution of the morphology of the polymer particles has been followed. This allowed us, to our best knowledge for the first time, to visualize "coagulative nucleation", which is the process where the primary nanoparticles aggregate into larger entities. The obtained visual information and data on particle size, number, and zeta potential, strongly suggest that coagulative termination is responsible for the coagulative nucleation phenomenon, resulting in a dispersion of fine, relatively uniform polymer particles. PMID:23965135

Dobrowolska, Marta E; van Esch, Jan H; Koper, Ger J M

2013-09-17

28

Cutting fluid emulsions produced by dilution of a cutting fluid concentrate containing a cationic\\/nonionic surfactant mixture  

Microsoft Academic Search

A cutting fluid concentrate has been formulated from a paraffinic oil, a hard water, MonoEthanolamine Borate (MEAB) and a cationic\\/nonionic surfactant mixture. Its dilution with hard water yields very stable oil-in-water emulsions, the so-called cutting fluid emulsion, with an average droplet diameter of 50nm, independently of both the hardness of water and the weight ratio of hard water to concentrate.

H. Bataller; S. Lamaallam; J. Lachaise; A. Graciaa; C. Dicharry

2004-01-01

29

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

NASA Astrophysics Data System (ADS)

Lattice Boltzmann simulations were used to study the coalescence kinetics in emulsions with amphiphilic surfactant, under neutrally buoyant conditions, and with a significant kinematic viscosity contrast between the phases (emulating water in oil emulsions). The 3D simulation domain was large enough (2563 ~ 107 grid points) to obtain good statistics with droplet numbers ranging from a few thousand at early times to a few hundred near equilibrium. Increased surfactant contents slowed down the coalescence rate between droplets due to the Gibbs-Marangoni effect, and the coalescence was driven by a quasi-turbulent velocity field. The kinetic energy decayed at a relatively slow rate at early times, due to conversion of interfacial energy to kinetic energy in the flow during coalescence. Phenomenological, coupled differential equations for the mean droplet diameter D(t) and the number density nd(t) were obtained from the simulation data and from film draining theories. Local (in time) power law exponents for the growth of the mean diameter (and for the concomitant decrease of nd) were established in terms of the instantaneous values of the kinetic energy, coalescence probability, Gibbs elasticity, and interfacial area. The model studies indicated that true power laws for the growth of the droplet size and decrease of the number of droplets with time may not be justified, since the exponents derived using the phenomenological model were time dependent. In contrast to earlier simulation results for symmetric blends with surfactant, we found no evidence for stretched logarithmic scaling of the form D ~ [ln (ct)]? for the morphology length, or exponential scalings associated with arrested growth, on the basis of the phenomenological model.

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

2012-12-01

30

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

Microsoft Academic Search

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

Celia R. S. Buono; Edison Bittencourt

31

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

Microsoft Academic Search

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

C. R. S. Buono; E. Bittencourt

32

FORMULATION OF MODEL CUTTING-OIL WATER EMULSIONS USING PARAFFINIC OIL AND IONIC\\/NONIONIC SURFACTANT MIXTURE  

Microsoft Academic Search

Cutting-oil emulsions are marketed under the shape of concentrates that the user has to dilute. More often these concentrates are monophasic microemulsions. We show that this kind of microemulsions may be obtained while relying on the generalized concept of Winsor, which guides the manipulation of three formulation parameters, which in turn rationally modify the surfactant interactions with the oily and

H. BataMer; C. Dicharry; J. Lachaise; A. Graciaa

2000-01-01

33

Preparation of high internal water-phase double emulsions stabilized by a single anionic surfactant for fabricating interconnecting porous polymer microspheres.  

PubMed

Herein we report a one-step method to prepare high internal water-phase double emulsions (W/O/W) via catastrophic phase inversion of water-in-oil high internal phase emulsions (W/O HIPEs) stabilized solely by 12-acryloxy-9-octadecenoic acid (AOA) through increasing the content of water phase. This is the first time for double emulsions to be stabilized solely by a single small molecular surfactant, which are usually costabilized by both hydrophilic and hydrophobic surfactants. After neutralized with ammonia, AOA is confirmed to be capable of stabilizing both W/O emulsions and O/W emulsions, which may account for its unique ability to stabilize double emulsions. The effects of different conditions (including changing the concentrations of AOA and salt (NaCl), pH value, the polarity of oils, the addition interval of water and stirring rate, etc.) on the formation and the stability of double emulsions as well as the inversion point have been investigated by using optical microscopy and conductivity monitoring. Finally, porous polymer microspheres with high interconnection (polyHIPE microspheres) were fabricated by ?-ray initiated polymerization of the as-prepared double emulsions composed of different monomers (styrene, or n-butyl acrylate, or methyl methacrylate), which have been confirmed by scanning electron microscopy. Our method is facile and effective for preparing high interconnecting porous polymer microspheres without tedious post-treatment of the products in common emulsion polymerization due to the use of polymerizable surfactant. PMID:25265198

Li, Zichao; Liu, Huarong; Zeng, Lai; Liu, Hewen; Yang, Song; Wang, Yanmei

2014-10-21

34

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

PubMed

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

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

2012-11-01

35

Adsorptive behavior of surfactants on surface of Portland cement  

Microsoft Academic Search

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

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

2001-01-01

36

Stability of surfactant-free high internal phase emulsions and its tailoring morphology of porous polymers based on the emulsions  

Microsoft Academic Search

Stable water-in-oil (w\\/o) high internal phase emulsions (HIPEs) having an internal phase of up to 95 vol% were prepared. The poly(styrene-methyl methacrylate-acrylic acid) (P(St-MMA-AA)) copolymer particles were used as stabilizer. The HIPEs prepared with addition of copolymer particles to the aqueous phase were stabilized by copolymer particles initially, followed by the mixture of copolymer particles and copolymer as the particles eventually

Shengmiao Zhang; Yun Zhu; Ye Hua; Corinne Jegat; Jianding Chen; Mohamed Taha

2011-01-01

37

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

PubMed

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

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

2012-05-29

38

Influence of intravenous perfluorocarbon administration on the dynamic behavior of lung surfactant.  

PubMed

Intravenous administration of perfluorocarbon (PFC) compounds can lead to pulmonary hyperinflation and respiratory distress in some mammals. This study was designed to quantify the effects of two PFC emulsions on the dynamic behavior of lung surfactant and to demonstrate that PFC is retained in the liquid lining the lung. New Zealand White rabbits received isotonic saline (3 ml/kg), Fluosol (15 ml/kg) or Oxygent (90% perfluorooctyl-bromide emulsion, 3 ml/kg). After seven days we euthanized the animals and lavaged the lungs. Surface tension-surface area relationships (sigma-A loops) were measured with the lavage fluid placed in a Wilhelmy plate-oscillating bellows apparatus. Loop hysteresis area after Fluosol administration was 334 +/- 92 dyne-cm, significantly greater than after saline (203 +/- 36 dyne-cm) but not Oxygent (274 +/- 66 dyne-cm). Loop hysteresis slope was higher with Oxygent (0.8 +/- 0.4 dyne/cm3) than after saline (0.6 +/- 0.3 dyne/cm3) or Fluosol (0.5 +/- 0.1 dyne/cm3). 282 MHz 19F NMR spectral analysis demonstrates that both PFCs tested appear only in the extracellular fraction of the lavage fluid. These results show that pulmonary elimination of intravascular PFC leads to PFC presence in the liquid lining the airways where it alters surfactant dynamic mechanical behavior. PMID:9663334

Eckmann, D M; Swartz, M A; Gavriely, N; Glucksberg, M R; Grotberg, J B

1998-07-01

39

Phase behavior of laundry surfactants in polar solvents  

Microsoft Academic Search

Laundry surfactants are usually mixtures of ionic and nonionic detergents that exhibit a complex phase behavior. Here the\\u000a ternary phase behavior of an isotropic and a liquid crystalline (LC) surfactant mixture has been examined in water\\/solvent\\u000a systems. The size of the LC area in the ternary phase diagram was correlated to solvent parameters including the dielectric\\u000a constant and the Gordon

Marc C. A. Stuart; John C. Van de Pas; Jan B. F. N. Engberts

2006-01-01

40

Kinetics of Narrowly dispersed Latex Formation in a Surfactant-free Emulsion Polymerization of Styrene in Acetone-Water Mixture  

NASA Astrophysics Data System (ADS)

The kinetics of narrowly dispersed latex formation in a surfactant-free emulsion polymerization of styrene in acetone-water was studied by a combination of transmission electron microscopy and light scattering. The critical nuclei were experimentally observed and the formation of narrowly dispersed PS latex is proved to be originated from competitive growth kinetics. Spherical nuclei were regenerated via a microphase inversion of PS oligomer in 50% volume fraction acetone-water mixture at 70^oC. They follow a polydispersed log-normal distribution and the smallest nucleus with Rs 1.1nm is similar to critical nuclei. Note the spherical nuclei are not necessarily narrowly dispersed. Competitive growth kinetics makes smaller nuclei grow much faster than large nuclei in the subsequent polymerization process, resulting in narrowly dispersed PS latex. Two kinds of PS seed particles were added, separately, into two parallel surfactant-free emulsion polymerization batches of styrene in acetone-water mixture at 70^oC. It was found that the size of seed particles almost does not change, but the small size PS latex grows rapidly. Our fitting results proves competitive growth kinetics proposed by Vanderhoff and coworkers.

Cheng, He; Li, Zhiyong; Han, Charles

2012-02-01

41

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

E-print Network

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

Huang, Jianbin

42

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

NASA Astrophysics Data System (ADS)

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

MacLean, Duncan A.

43

Comparison of the Rheological Behavior of Solutions and Formulated Oil in Water Emulsions Containing Carboxymethylcellulose (CMC)  

Microsoft Academic Search

In this study, it was aimed to compare the rheological properties of Carboxymethylcellulose (CMC) in aqueous solutions and their corresponding emulsions containing 0.05, 0.1, 0.25 and 0.5% CMC in the aqueous phase. Samples with 0.05 and 0.1% CMC showed Newtonian behavior but shear-thinning behavior was observed in CMC solutions and emulsions with increasing CMC concentrations to 0.25 and 0.5%. Rheological

Mohsen Radi; Sedigheh Amiri

2012-01-01

44

Reverse water-in-fluorocarbon emulsions and microemulsions obtained with a fluorinated surfactant  

Microsoft Academic Search

Neat fluorocarbons (FCs) are being investigated for pulmonary delivery of drugs and genes, triggering interest on reverse water-in-fluorocarbon emulsions as delivery systems for hydrophilic bioactive materials to the lung. In this paper we examine the ability of a series of perfluoroalkylated amphiphiles with a dimorpholinophosphate polar head group, CnF2n+1(CH2)mOP(O)[N(CH2CH2)2O]2 (FnHmDMP, n = 4, 6, 8, 10 and m = 2,

Hélène M. Courrier; Thierry F. Vandamme; Marie Pierre Krafft

2004-01-01

45

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

E-print Network

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

Mulqueen, Michael (Michael Patrick), 1972-

2001-01-01

46

Emulsion of an in-situ surfactant in petroleum. Final report  

SciTech Connect

Three emulsifiers were tested for their ability to reduce the viscosity of heavy oils. A reduction of 25% viscosity is achieved using polybutene. A reduction of 50% viscosity is achieved using a concentrated ionic detergent obtained from SANDOZ. The most promising emulsifiers is a lipopeptide. Preliminary studies show this emulsifier reduces the viscosity of heavy oils by as much as 80%. It is also able to reduce the surface tension of water by 35%. This emulsifier is also biodegradable and less toxic than synthetic surfactants. (DMC)

Not Available

1983-12-01

47

Polymerization in emulsion microdroplet reactors  

NASA Astrophysics Data System (ADS)

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

Carroll, Nick J.

48

The stability behavior of sol-emulsion systems  

SciTech Connect

Sol-emulsion systems, i.e., colloids consisting of mixed populations of solid particles and emulsion droplets, are encountered in a number of applications, e.g., oil-assisted agglomeration for particle removal (coal fines from water). The stability characteristics of mixed aqueous dispersions of titanium dioxide and mineral oil emulsion droplets are examined as a function of pH and emulsifier type and content. Zeta potentials of both the titanium dioxide and the mineral oil particles are measured under all conditions to identify regions of expected heterocoagulation and to quantify the electrostatic boundary conditions. The latter are used in the numerical solution of the pair interaction potentials based on the recent theory of McCormack et al. The potential functions are used in a modified version of the stability model of Hogg, Healy, and Fuerstenau to calculate early-stage aggregation rates. Photon correlation spectroscopy is used to determine stability ratios for homo- and heterocoagulation, and initial results indicate good agreement between experiments and computations.

Sunkel, J.M.; Berg, J.C. [Univ. of Washington, Seattle, WA (United States). Dept. of Chemical Engineering] [Univ. of Washington, Seattle, WA (United States). Dept. of Chemical Engineering

1996-05-10

49

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

E-print Network

Effect of Shear Flow on the Phase Behavior of an Aqueous Gelatin-Dextran Emulsion Y. A. Antonov, P and on a time resolved basis the shear induced morphology in ternary two-phase water-gelatin-dextran mixtures a critical shear rate, shear-induced mixing occurs at the length scales probed by the laser light

50

Study of Highly Concentrated Olive Oil-in-Water Emulsions Stabilized by Palm-Based Nonionic Surfactant (Kajian Emulsi Minyak Zaitun-dalam-Air Berkepekatan Tinggi Distabilkan dengan Surfaktan Nonionik Berasaskan Sawit)  

Microsoft Academic Search

Rheological properties of highly concentrated oil-in-water (O\\/W) emulsions (HCEs), formed by mixing palm-based nonionic surfactant, C 12 E 6 (HLB = 11.7, CMC = 25µM), water and olive oil volume fraction ! 78vol% were investigated. Samples with lower oil volume fraction (<85%) and surfactant concentration (<8%) exhibited polydispersity of broader droplet size distribution (DSD). In contrast, samples with higher oil

LIM HONG NGEE; ANUAR KASSIM; HUANG NAY MING; AMBAR YARMO; YEONG SHOOT KIAN

2009-01-01

51

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

PubMed Central

Background: The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters. Methods: Nonionic surfactant blends of Tween® and Tween®/Span® series were screened based on their solubilization capacity with water for palm kernel oil esters. Tween® 80 and five blends of Tween® 80/Span® 80 and Tween® 80/Span® 85 in the hydrophilic-lipophilic balance (HLB) value range of 10.7–14.0 were selected to study the phase diagram behavior of palm kernel oil esters using the water titration method at room temperature. Results: High solubilization capacity was obtained by Tween® 80 compared with other surfactants of Tween® series. High HLB blends of Tween® 80/Span® 85 and Tween® 80/Span® 80 at HLB 13.7 and 13.9, respectively, have better solubilization capacity compared with the lower HLB values of Tween® 80/Span® 80. All the selected blends of surfactants were formed as water-in-oil microemulsions, and other dispersion systems varied in size and geometrical layout in the triangles. The high solubilization capacity and larger areas of the water-in-oil microemulsion systems were due to the structural similarity between the lipophilic tail of Tween® 80 and the oleyl group of the palm kernel oil esters. Conclusion: This study suggests that the phase diagram behavior of palm kernel oil esters, water, and nonionic surfactants is not only affected by the HLB value, but also by the structural similarity between palm kernel oil esters and the surfactant used. The information gathered in this study is useful for researchers and manufacturers interested in using palm kernel oil esters in pharmaceutical and cosmetic preparation. The use of palm kernel oil esters can improve drug delivery and reduce the cost of cosmetics. PMID:21792294

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

2011-01-01

52

Thickness-Dependent Surfactant Behavior in Trilayer Polymer Films  

NASA Astrophysics Data System (ADS)

The ability for thin liquid films to wet and remain thermodynamically stable on top of one another is a fundamental challenge in developing high quality paints, coatings, adhesives, and other industrial products. Since intermolecular interactions and interfacial energies dominate in the film thickness regime from tens to hundreds of nanometers, it is desirable to tune these long-range and short-range forces in a simple, controllable manner. Starting from an unstable model homopolymer bilayer (poly(styrene)/poly(4-vinylpyridine)), we demonstrate that sandwiching an additional homopolymer layer (poly(4-bromostyrene)) between the two layers can provide needed surfactancy. As the thickness of this center layer is increased, the full trilayer transitions from unstable (thin) to stable (moderate) to unstable (thick). We experimentally show using x-ray standing waves generated via total external reflection (TER-XSW), atomic force microscopy (AFM), and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) that this behavior can be directly attributed to the autophobic dewetting phenomenon, in which the surfactant layer is thin enough to remain stable but thick enough to shield the neighboring layers, highlighting a general approach to stabilizing multilayer systems.

Sun, Yan; Shull, Kenneth; Wang, Jin

2010-03-01

53

Yielding and flow in adhesive and nonadhesive concentrated emulsions.  

PubMed

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

Bécu, Lydiane; Manneville, Sébastien; Colin, Annie

2006-04-01

54

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

NASA Astrophysics Data System (ADS)

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

Billeter, Jeffrey L.; Pelcovits, Robert A.

2000-07-01

55

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

Microsoft Academic Search

Sedimentation of a suspension of particles under the action of gravity has been studied extensively due to its importance in practical applications such as oil sands extraction, solid-liquid separation, particle size measurement, dewatering of coal slurries, clarification of waste water, and processing of drilling and mining fluids containing rocks and mineral particles of various sizes. Creaming behavior of oil-in-water emulsions

Nianxi Yan; Jacob H. Masliyah

1997-01-01

56

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

E-print Network

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

57

Aggregation Behavior of Charged Surfactants and their Mixtures in Ionic Liquids  

NASA Astrophysics Data System (ADS)

Room-temperature ionic liquids (ILs) have been recently explored as extraordinary solvent with potential opportunities for numerous applications. We set out to obtain a better understanding of the aggregation behavior of charged surfactants within ILs. From phase diagrams and isotherms in several distinct ILs, a connection between solubility of the surfactant and the physical properties of the underlying ionic liquid was established. We conclude that the interfacial energy is crucial in determining aggregation behavior while electrostatic interactions can be largely ignored. This study was extended to include mixtures of cationic and anionic surfactants where our data further demonstrate near-complete charge screening. Mixtures of charged surfactants in ILs can therefore be considered as nearly ideal, in sharp contrast to aqueous solutions. The results here give insight into the nature of self-assembly of surfactants in ILs and the interaction between solutes and IL solvents.

Chen, Lang; Bermudez, Harry

2013-03-01

58

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...

59

Water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction for the determination of fungicides in wine.  

PubMed

A sample preparation method, dispersive liquid-liquid microextraction assisted by an emulsion with low concentration of a surfactant in water and dispersed solvent coupled with gas chromatography-mass spectrometry, was developed for the analysis of the fungicides cyprodinil, procymidone, fludioxonil, flusilazole, benalaxyl, and tebuconazole in wine. A microsyringe was used to withdraw and discharge a mixture of extraction solvent and 240 ?L of an aqueous solution of Triton X-100 (the dispersed agent) four times within 10 s to form a cloudy emulsion in the syringe. This emulsion was then injected into a 5 mL wine sample spiked with all of the above fungicides. The total extraction time was approximately 0.5 min. Under optimum conditions using 1-octanol (12 ?L) as extraction solvent, the linear range of the method in analysis of all six fungicides was 0.05-100 ?g L(-1), and the limit of detection ranged from 0.013 to 0.155 ?g L(-1). The absolute recoveries (n = 3) and relative recoveries (n = 3) were 30-83 and 81-108% for white wine at 0.5, 5, and 5 ?g L(-1), and 30-92 and 81-110% for red wine, respectively. The intraday (n = 7) and interday (n = 6) relative standard deviations ranged from 4.4 to 8.8% and from 4.3 to 11.2% at 0.5 ?g L(-1), respectively. The method achieved high enrichment factors. It is an alternative sample preparation technique with good performance. PMID:25152072

Tseng, Wan-Chi; Chu, Shang-Ping; Kong, Po-Hsin; Huang, Chun-Kai; Chen, Jung-Hsuan; Chen, Pai-Shan; Huang, Shang-Da

2014-09-17

60

How do (fluorescent) surfactants affect particle-stabilized emulsions? Job H. J. Thijssen,* Andrew B. Schofield and Paul S. Clegg  

E-print Network

components in mixed- emulsifier systems may also have specific functions. During emulsi- fication, however, competition rather than synergy between molecular and particulate emulsifiers has been observed effects between particulate and molecular emulsifiers, we start with a reference emulsion of water and oil

Schofield, Andrew B.

61

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

E-print Network

AN INVESTIGATION OF THE BEHAVIOR OF RADIOACTIVATED SURFACTANTS IN LINEAR, UNCONSOLIDATED SAND SYSTEMS A Thesis RAMON T. RIVERO Submitted to the Graduate College of the Texas A k M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE January 1964 Ma )or Sub]ect: Petroleum Engineering AN INVESTIGATION OF THE BEHAVIOR OF RADIOACTIVATFD SURFACTANTS IN LINEAR, UNCONSOLIDATED SAND SYSTEMS A Thesis by RAMON T ~ RIVERO Approved as to style and content by...

Rivero, Ramon T

2012-06-07

62

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

PubMed

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

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

2013-04-23

63

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

E-print Network

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

Huang, Jianbin

64

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

PubMed

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

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

2014-03-01

65

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

PubMed

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

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

2012-07-17

66

Discrepancy between phase behavior of lung surfactant phospholipids and the classical model of surfactant function.  

PubMed Central

The studies reported here used fluorescence microscopy and Brewster angle microscopy to test the classical model of how pulmonary surfactant forms films that are metastable at high surface pressures in the lungs. The model predicts that the functional film is liquid-condensed (LC) and greatly enriched in dipalmitoyl phosphatidylcholine (DPPC). Both microscopic methods show that, in monolayers containing the complete set of phospholipids from calf surfactant, an expanded phase persists in coexistence with condensed domains at surface pressures approaching 70 mN/m. Constituents collapsed from the interface above 45 mN/m, but the relative area of the two phases changed little, and the LC phase never occupied more than 30% of the interface. Calculations based on these findings and on isotherms obtained on the continuous interface of a captive bubble estimated that collapse of other constituents increased the mol fraction of DPPC to no higher than 0.37. We conclude that monolayers containing the complete set of phospholipids achieve high surface pressures without forming a homogeneous LC film and with a mixed composition that falls far short of the nearly pure DPPC predicted previously. These findings contradict the classical model. PMID:11566788

Piknova, B; Schief, W R; Vogel, V; Discher, B M; Hall, S B

2001-01-01

67

Petroleum emulsions, micro-emulsions, and micellar solutions  

Microsoft Academic Search

Petroleum is a micellar solution of asphaltenes and resins. Crude oils mostly are recovered as water in oil emulsions. Micro-emulsions\\u000a in the state of phase inversion are very important for an enhanced oil recovery by surfactant flooding.\\u000a \\u000a The results of investigations on the composition and the properties of asphaltenes and petroleum resins are discussed along\\u000a with the importance of micro-emulsions

H.-J. Neumann; B. Paczy?ska-Lahme

68

Characterization and Interfacial Behavior of Oil Sands Solids Implicated in Emulsion Stability  

Microsoft Academic Search

Model water?in?hydrocarbon emulsions were used to assess the configuration of oil sands solids in the interfacial region. The model emulsions consisted of toluene, heptane, and water as well as asphaltenes and solids separated from Athabasca bitumen. A combination of emulsion gravimetric measurements, water drop size measurements, and geometrical considerations was employed to determine the fractional area of the interface occupied

Danuta M. Sztukowski; Harvey W. Yarranton

2004-01-01

69

Condensation and decondensation of DNA by cationic surfactant, spermine, or cationic surfactant-cyclodextrin mixtures: macroscopic phase behavior, aggregate properties, and dissolution mechanisms.  

PubMed

The macroscopic phase behavior and other physicochemical properties of dilute aqueous mixtures of DNA and the cationic surfactant hexadecyltrimethylammounium bromide (CTAB), DNA and the polyamine spermine, or DNA, CTAB, and (2-hydroxypropyl)-?-cyclodextrin (2HP?CD) were investigated. When DNA is mixed with CTAB we found, with increasing surfactant concentration, (1) free DNA coexisting with surfactant unimers, (2) free DNA coexisting with aggregates of condensed DNA and CTAB, (3) a miscibility gap where macroscopic phase separation is observed, and (4) positively overcharged aggregates of condensed DNA and CTAB. The presence of a clear solution beyond the miscibility gap cannot be ascribed to self-screening by the charges from the DNA and/or the surfactant; instead, hydrophobic interactions among the surfactants are instrumental for the observed behavior. It is difficult to judge whether the overcharged mixed aggregates represent an equilibrium situation or not. If the excess surfactant was not initially present, but added to a preformed precipitate, redissolution was, in consistency with previous reports, not observed; thus, kinetic effects have major influence on the behavior. Mixtures of DNA and spermine also displayed a miscibility gap; however, positively overcharged aggregates were not identified, and redissolution with excess spermine can be explained by electrostatics. When 2HP?CD was added to a DNA-CTAB precipitate, redissolution was observed, and when it was added to the overcharged aggregates, the behavior was essentially a reversal of that of the DNA-CTAB system. This is attributed to an effectively quantitative formation of 1:1 2HP?CD-surfactant inclusion complexes, which results in a gradual decrease in the concentration of effectively available surfactant with increasing 2HP?CD concentration. PMID:22546152

Carlstedt, Jonas; Lundberg, Dan; Dias, Rita S; Lindman, Björn

2012-05-29

70

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

NASA Astrophysics Data System (ADS)

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

Kulaots, Indrek

71

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

PubMed

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

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

2014-02-19

72

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

PubMed

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

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

2013-05-21

73

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

PubMed

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

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

2009-08-01

74

Interfacial properties in solid-stabilized emulsions  

NASA Astrophysics Data System (ADS)

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

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

2005-04-01

75

Micellization Behavior of Cationic Gemini Surfactants in Aqueous-Ethylene Glycol Solution  

Microsoft Academic Search

The micellization behavior of gemini surfactants i.e. alkanediyl-?,?-bis(cetyldimethylammonium bromide) (C16-s-C16,2Br? where s = 3, 4, 10) in 10% (v\\/v) ethylene glycol solution was investigated by surface tension and conductometric measurements at\\u000a 300 K. The critical micelle concentration, degree of micellar ionization, surface excess concentration, minimum surface area\\u000a per molecule of surfactant, surface pressure at the CMC and Gibbs energy of adsorption of the

Deepti Tikariha; Birendra Kumar; Namrata Singh; Kallol K. Ghosh; Pierluigi Quagliotto

76

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

PubMed Central

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

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

2010-01-01

77

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

PubMed

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

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

2014-07-01

78

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

PubMed

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

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

2013-03-21

79

Emulsions stabilised solely by colloidal particles  

Microsoft Academic Search

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

Robert Aveyard; Bernard P Binks; John H Clint

2003-01-01

80

Surfactant development for enhanced oil recovery. Seventh quarterly report, July--September 1995  

SciTech Connect

Aqueous dihexadecyldimethylammonium bromide (DHDAB) surfactant was used to form an emulsion with samples of crude oil (Burbank Crude Oil) supplied by Phillips Petroleum Company. Influence of the surfactant concentration in the uptake of the oil in the aqueous phase was studied. It was observed that as weight of the surfactant solubilized in the oil-water system increases the volume of oil solubilized in the aqueous phase increases. Viscosity of the emulsion was also observed to increase with an increase in the weight of surfactant added. A co-surfactant, n-butyl alcohol was added and its effect was to reverse the observation described above. The uptake of aqueous surfactant into the oil phase was very evident. Salinity scan of this system showed that the addition of sodium chloride, NaCl, produced a middle phase whose volume increased with an increase in the amount of salt added. Also there was observed, a remarkable high salinity tolerance. Rheology of the emulsion showed typical non-Newtonian behavior. The emulsion was observed to exhibit a pseudoplastic profile. The shear-thinning profile was evident from the observed viscosity-shear rate experiment.

NONE

1996-06-01

81

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

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, ?-endosulfan, 4,4-DDE, 2,4-DDD and endrin, in aqueous samples. A microsyringe is used to withdrew and discharge 10-12?L of the extraction solvent and 60-120?L 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 (12?L) 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

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

2013-07-26

82

Aggregation Behavior of Tyloxapol, a Nonionic Surfactant Oligomer, in Aqueous Solution  

Microsoft Academic Search

The aggregation behavior of Tyloxapol, a nonionic surfactant oligomer with a repeating unit close to Triton X-100 (TX100), and a maximum degree of polymerization of about 7, has been investigated in aqueous solution by means of fluorescence probing, time-resolved fluorescence quenching (TRFQ) and transmission electron microscopy at cryogenic temperature (cryo-TEM). The plot of the pyrene fluorescence intensity ratioI1\\/I3against the Tyloxapol

Oren Regev; Raoul Zana

1999-01-01

83

Investigating the effect of particle size on pulmonary surfactant phase behavior.  

PubMed

We study the impact of the addition of particles of a range of sizes on the phase transition behavior of lung surfactant under compression. Charged particles ranging from micro- to nanoscale are deposited on lung surfactant films in a Langmuir trough. Surface area versus surface pressure isotherms and fluorescent microscope observations are utilized to determine changes in the phase transition behavior. We find that the deposition of particles close to 20 nm in diameter significantly impacts the coexistence of the liquid-condensed phase and liquid-expanded phase. This includes morphological changes of the liquid-condensed domains and the elimination of the squeeze-out phase in isotherms. Finally, a drastic increase of the domain fraction of the liquid-condensed phase can be observed for the deposition of 20-nm particles. As the particle size is increased, we observe a return to normal phase behavior. The net result is the observation of a critical particle size that may impact the functionality of the lung surfactant during respiration. PMID:25296309

Kodama, Akihisa T; Kuo, Chin-Chang; Boatwright, Thomas; Dennin, Michael

2014-10-01

84

Influence of oil polarity on droplet growth in oil-in-water emulsions stabilized by a weakly adsorbing biopolymer or a nonionic surfactant.  

PubMed

The influence of oil type (n-hexadecane, 1-decanol, n-decane), droplet composition (hexadecane:decanol), and emulsifier type (Tween 20, gum arabic) on droplet growth in oil-in-water emulsions was studied. Droplet size distributions of emulsions were measured over time (0-120 h) by laser diffraction and ultrasonic spectroscopy. Emulsions containing oil molecules of low polarity and low water solubility (hexadecane) were stable to droplet growth, irrespective of the emulsifier used to stabilize the droplets. Emulsions containing oil molecules of low polarity and relatively high water solubility (decane) were stable to coalescence, but unstable to Ostwald ripening, irrespective of emulsifier. Droplet growth in emulsions containing oil molecules of relatively high polarity and high water solubility (decanol) depended on emulsifier type. Decanol droplets stabilized by Tween 20 were stable to droplet growth in concentrated emulsions but unstable when the emulsions were diluted. Decanol droplets stabilized by gum arabic exhibited rapid and extensive droplet growth, probably due to a combination of Ostwald ripening and coalescence. We proposed that coalescence was caused by the relatively low interfacial tension at the decanol-water boundary, which meant that the gum arabic did not absorb strongly to the droplet surfaces and therefore did not prevent the droplets from coming into close proximity. PMID:16290453

Chanamai, Ratjika; Horn, Gregory; McClements, David Julian

2002-03-01

85

Rheological behavior and parameters of the in vitro model of lung surfactant systems: the role of the main phospholipid component.  

PubMed

The proposed in vitro model for studying the alveolar surface layer of the lungs enables one to investigate the surface intermolecular forces which influence the stability of the alveolus. The general role for the stability of the alveolus belongs to the phospholipids in the alveolar surfactant and predominantly to their main component dipalmitoylphosphatidylcholine (DPPC). The aim of the study was to investigate the rheological behavior of DPPC and exogenous surfactant preparations used in neonatal clinical practice. Data for the rheological behavior of the solutions of the commercially available surfactants, Infasurf, Exosurf and Survanta, as well as of DPPC (their main phospholipid component) at shear rates from 0.024 to 94.5 s(-1) under steady and transient flow conditions at 23 degrees C were obtained. Infasurf and Exosurf showed Newtonian rheological behavior, while Survanta revealed the shear-thinning behavior of a non-Newtonian pseudoplastic fluid. The rheological properties of aqueous solutions of DPPC containing 0.14 M NaCl at concentrations from 100 and 630 microg/ml of phospholipid (chosen from the dependence of the probability for bilayer film formation) were studied. Differences observed in the rheological properties of the exogenous surfactants were interpreted on the basis of their composition, the presence of other phospholipid components, certain additives and surfactant proteins, as well as the bulk structures formed from them. The relevance of the results for the delivery of exogenous surfactants and their spreading in replacement therapy is discussed. PMID:12897419

Antonova, Nadia; Todorov, Roumen; Exerowa, Dotchi

2003-01-01

86

Demulsification of Emulsions Exploited by Enhanced Oil Recovery System  

Microsoft Academic Search

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

Lixin Xia; Shiwei Lu; Guoying Cao

2003-01-01

87

Effect of amyl alcohol on the phase behavior of carboxymethylated ethoxylates of isononylphenol in a surfactant-water-hydrocarbon system  

Microsoft Academic Search

According to its behavior in a surfactant-water-hydrocarbon system containing electrolytes, the molecular and component composition of a surfactant with the products of carboxymethylation of ethoxylates of isononylphenol has been optimized for the Windsor microemulsion state III. For the condition of the occurrence of an ultra-low interphase tension at a water-octane interface, a mathematical description is presented of the optimum volume

V. I. Lysenko; V. G. Germashev; V. D. Gusev

1988-01-01

88

Surfactant behavior and its influence on the viscosity of associative thickeners solutions, thickened latex dispersions, and waterborne latex coatings  

Microsoft Academic Search

Surfactants, varying in their chemical composition and hydrophobic behavior, are used in the formulation of a waterborne coating.\\u000a These differences influence their aggregation in micellar structures, their interaction with associative thickeners, and in\\u000a particular, the synergies present in their competitive adsorptions on the disperse phases in a waterborne coating. Adsorption\\u000a of HEUR thickeners on latexes and the ability of surfactants

David M. Mahli; Mark J. Steffenhagen; Lin-lin Xing; J. Edward Glass

2003-01-01

89

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

SciTech Connect

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

P. Somasundaran

2004-11-20

90

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

Microsoft Academic Search

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

Raoul Zana

2002-01-01

91

Models of gemini surfactants  

E-print Network

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

Haim Diamant; David Andelman

2003-02-10

92

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

PubMed Central

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

Ochs, Matthias; Proquitte, Hans; Mense, Lars; Rudiger, Mario

2012-01-01

93

Shape-changing and amphiphilicity-reversing Janus particles with pH-responsive surfactant properties.  

PubMed

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

Tu, Fuquan; Lee, Daeyeon

2014-07-16

94

Emulsifying Properties of Legume Proteins Compared to ?-Lactoglobulin and Tween 20 and the Volatile Release from Oil-in-Water Emulsions.  

PubMed

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

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

2014-10-01

95

Thermally cleavable surfactants  

DOEpatents

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.

McElhanon, James R. (Manteca, CA); Simmons, Blake A. (San Francisco, CA); Zifer, Thomas (Manteca, CA); Jamison, Gregory M. (Albuquerque, NM); Loy, Douglas A. (Albuquerque, NM); Rahimian, Kamyar (Albuquerque, NM); Long, Timothy M. (Urbana, IL); Wheeler, David R. (Albuquerque, NM); Staiger, Chad L. (Albuquerque, NM)

2006-04-04

96

Thermally cleavable surfactants  

DOEpatents

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.

McElhanon, James R. (Manteca, CA); Simmons, Blake A. (San Francisco, CA); Zifer, Thomas (Manteca, CA); Jamison, Gregory M. (Albuquerque, NM); Loy, Douglas A. (Albuquerque, NM); Rahimian, Kamyar (Albuquerque, NM); Long, Timothy M. (Urbana, IL); Wheeler, David R. (Albuquerque, NM); Staiger, Chad L. (Albuquerque, NM)

2009-09-29

97

Thermally cleavable surfactants  

DOEpatents

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.

McElhanon, James R. (Manteca, CA); Simmons, Blake A. (San Francisco, CA); Zifer, Thomas (Manteca, CA); Jamison, Gregory M. (Albuquerque, NM); Loy, Douglas A. (Albuquerque, NM); Rahimian, Kamyar (Albuquerque, NM); Long, Timothy M. (Urbana, IL); Wheeler, David R. (Albuquerque, NM); Staiger, Chad L. (Albuquerque, NM)

2009-11-24

98

Investigation of the wetting behavior of coal tar in three phase systems and its modification by poloxamine block copolymeric surfactants.  

PubMed

The removal of dense nonaqueous phase liquid mixtures (DNAPLs) from rocks and subsurface soils is an ongoing remedial challenge. Very often the wetting preferences of the system are not altered by exposure to the DNAPL. However, there are systems where the wetting properties of the solid phase have been altered from strongly water wetting by exposure to the DNAPL. In these cases some technique is necessary for reducing the work of adhesion between the DNAPL and the mineral surface. The focus of this report is the problems posed by coal tar in unconsolidated sands. It is shown that coal tar can alter the wetting properties of quartz, the principal component of sands, and is thus capable of adhering to the surface. In this investigation the ability of several members of the poloxamine family of polymeric surfactants to aid in the removal of coal tar from sand was evaluated. The poloxamines are tetrafunctional block copolymeric surfactants, which contain four poly(ethylene oxide)-block-poly(propylene oxide) chains joined to a central ethylenediamine moiety via the nitrogen atoms. Contact angle measurements of coal tar on a quartz surface immersed in aqueous surfactant solution and the interfacial tension between coal tar and aqueous surfactant solution have been measured. Coal tar/water interfacial tensions are reduced to values in the region of 2 mN m(-1) at surfactant concentrations of approximately 0.1 w/v %. Poloxamine surfactant impact on the static contact angle is more complex. In some cases the polymeric surfactants alter the wetting behavior from strongly water wetting to weakly water wetting. However, other poloxamines appear to have little if any impact on the contact angle, which remains strongly water wetting. The foregoing measurements have then been used to calculate the work of adhesion of the coal tar to quartz and the results qualitatively compared with the concentration of surfactant solution required to visually demonstrate the complete de-adhesion of coal tar to the quartz. It is shown that at surfactant concentrations below the critical micelle concentration (cmc) of the surfactant, the work of adhesion can be reduced sufficiently to ensure complete removal of coal tar from both quartz and sand. PMID:14750737

Dong, Jingfeng; Chowdhry, Babur; Leharne, Stephen

2004-01-15

99

Effect of amyl alcohol on the phase behavior of carboxymethylated ethoxylates of isononylphenol in a surfactant-water-hydrocarbon system  

SciTech Connect

According to its behavior in a surfactant-water-hydrocarbon system containing electrolytes, the molecular and component composition of a surfactant with the products of carboxymethylation of ethoxylates of isononylphenol has been optimized for the Windsor microemulsion state III. For the condition of the occurrence of an ultra-low interphase tension at a water-octane interface, a mathematical description is presented of the optimum volume of amyl alcohol in the system, in the form of a linear dependence on the degree of oxyethylation of the alkylphenol and the degree of carboxymethylation of the ethoxylates. An estimate is made of the contribution of the carboxymethyl and ethoxyl groups to the increase of the hydrophilic-lipophilic balance of the surfactant.

Lysenko, V.I.; Germashev, V.G.; Gusev, V.D.

1988-03-01

100

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

PubMed

Cationic gemini surfactant homologues alkanediyl-?,?-bis(dodecyldiethylammonium bromide), [C(12)H(25)(CH(3)CH(2))(2)N(CH(2))(S)N(CH(2)CH(3))(2)C(12)H(25)]Br(2) (where S=2, 4, 6, 8, 10, 12, 16, 20), referred to as C(12)C(S)C(12)(Et) were synthesized systematically. This paper focused on various properties of the above gemini surfactants in order to give a full understanding of this series of surfactants. The following points are covered: (1) surface properties, which include (i) effect of the spacer carbon number on the general properties and (ii) the effect of added NaBr on the general surface properties; (2) aggregation behavior in bulk solution, including (i) morphologies of above gemini surfactants classed as having short spacers, middle-length spacers and long spacers and (ii) superior vesicle stability against high NaBr concentration for the long spacer gemini surfactants; (3) thermodynamic properties during micellization and the effect of spacer carbon number on them; and (4) perspectives for the further use and application of these compounds. PMID:22513166

Lu, Ting; Lan, Yuru; Liu, Chenjiang; Huang, Jianbin; Wang, Yilin

2012-07-01

101

Yielding and flow in adhesive and non-adhesive concentrated emulsions  

E-print Network

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

L. Becu; S. Manneville; A. Colin

2006-03-07

102

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

Microsoft Academic Search

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

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

2009-01-01

103

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

PubMed

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

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

2014-03-15

104

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

PubMed

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 (|?*|), and the yield stress (?0) 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 the rheological properties. PMID:21288036

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

2011-03-15

105

Phase behavior and rheological properties of salt-free catanionic surfactant mixtures in the presence of bile acids.  

PubMed

The phase behavior, rheological properties, and structures of two salt-free catanionic surfactant systems, tetradecyltrimethylammonium hydroxide ((TTA)OH)/lauric acid (LA)/H(2)O and cetyltrimethylammonium hydroxide ((CTA)OH)/LA/H(2)O, in the presence of deoxycholic acid (DeCA) were investigated and compared with the results of cholic acid (CA). Small-angle X-ray scattering, deuterium nuclear magnetic resonance, and rheological measurements were employed to monitor the phase structure and transition. The surface tension was used to investigate the surface activities of the bile acid/(TTA)OH and bile acid/(CTA)OH mixtures in dilute solutions. The results show that they have a minimum surface tension in a solution with excess cationic surfactant, and the critical micelle concentration decreases with an increase of the cationic surfactant chain length and hydrophobicity of the bile acids. At equimolar mixtures of DeCA and cationic surfactants, or DeCA being in excess, phase separation occurs with a large diameter of droplets in the upper phase and a small volume of viscous liquid in the bottom phase. Compared with CA systems, in the salt-free catanionic surfactant systems containing DeCA, phase transition from the birefringent L(alpha) phase to the L(1) phase occurs at a high molar fraction of DeCA, and the viscosity is higher at the same molar fraction of bile acid, indicating the significant influence of the molecule structures of bile acids despite only one hydroxyl group difference. Shear thickening is observed in the L(alpha) region, and a gradual evolvement of aggregates is predicted. Longer chain cationic surfactant can also increase the shear viscosity, which could be ascribed to the increase of the critical packing parameter, but with less influence on the phase transition. PMID:20617849

Liu, Changcheng; Hao, Jingcheng; Wu, Ziyu

2010-08-01

106

Analysis of emulsion stability in acrylic dispersions  

NASA Astrophysics Data System (ADS)

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 (?-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.

Ahuja, Suresh

2012-02-01

107

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

PubMed

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

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

2012-12-12

108

Relation between viscosity and stability for heavy oil emulsions  

E-print Network

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

Ye, Sherry Qianwen

2012-06-07

109

Polysaccharide/Surfactant complexes at the air-water interface - Effect of the charge density on interfacial and foaming behaviors  

E-print Network

The binding of a cationic surfactant (hexadecyltrimethylammonium bromide, CTAB) to a negatively charged natural polysaccharide (pectin) at air-solution interfaces, was investigated on single interfaces and in foams, versus the linear charge densities of the polysaccharide. Beside classical methods to investigate polymer/surfactant systems, we applied, for the first time concerning these systems, the analogy between the small angle neutron scattering by foams and the neutron reflectivity of films to measure in situ film thicknesses of foams. CTAB/pectin foam films are much thicker than that of the pure surfactant foam film but similar for highly and lowly charged pectin/CTAB systems despite the difference in structure of complexes at interfaces. The improvement of the foam properties of CTAB bound to pectin is shown to be directly related to the formation of pectin-CTAB complexes at the air-water interface. However, in opposition to surface activity, there is no specific behavior for the highly charged pectin: foam properties depend mainly upon the bulk charge concentration, while the interfacial behavior is mainly governed by the charge density of pectin. For the highly charged pectin, specific cooperative effects between neighboring charged sites along the chain are thought to be involved in the higher surface activity of pectin/CTAB complexes. A more general behavior can be obtained at lower charge density either by using a lowly charged pectin or by neutralizing the highly charged pectin in decreasing pH. .

Marie-Hélène M. H. Ropers; Bruno Novales; François Boué; Monique A. V. Axelos

2010-05-11

110

Synthesis and characterization of porous glycidylmethacrylate–divinylbenzene monoliths using the high internal phase emulsion approach  

Microsoft Academic Search

Highly porous monoliths were synthesised using glycidyl methacrylate (GMA) and divinylbenzene in the presence of a porogen, and emulsion templating as the preparation technique (polyHIPEs). Two surfactants were used as the emulsion stabiliser. It turned out that the choice of the surfactant was essential for the successful synthesis of polyHIPEs containing large amount of the functional monomer GMA, and characterised

Andrea Barbetta; Mariella Dentini; Lorenzo Leandri; Giovanni Ferraris; Alessandro Coletta; Manuele Bernabei

2009-01-01

111

Zero-Valent Metal Emulsion for Reductive Dehalogenation of DNAPLs  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

112

Zero-Valent Metal Emulsion for Reductive Dehalogenation of DNAPLS  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

113

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

PubMed

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

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

2013-12-01

114

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

PubMed

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

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

2011-09-01

115

Shear-Induced Deformation of Surfactant Multilamellar Vesicles  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

116

Potential commercial applications of microbial surfactants  

Microsoft Academic Search

Surfactants are surface-active compounds capable of reducing surface and interfacial tension at the interfaces between liquids,\\u000a solids and gases, thereby allowing them to mix or disperse readily as emulsions in water or other liquids. The enormous market\\u000a demand for surfactants is currently met by numerous synthetic, mainly petroleum-based, chemical surfactants. These compounds\\u000a are usually toxic to the environment and non-biodegradable.

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

2000-01-01

117

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

PubMed

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

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

2011-09-20

118

Polymorphic behavior in protein-surfactant mixtures: the water-bovine serum albumin-sodium taurodeoxycholate system.  

PubMed

Mixtures containing water, bovine serum albumin (BSA), and sodium taurodeoxycholate (NaTDC), a component of the bile in mammals, have been investigated in a wide range of composition and pH. Depending on the concentration of both solutes and the pH, solutions, precipitates, and gels are formed. Under spontaneous pH conditions, the transport properties in dilute solutions indicate the occurrence of significant interactions between BSA and the surfactant. Conversely, acidic media favor the formation of nonsoluble protein-surfactant complexes, with subsequent precipitation. The nucleation kinetics of the protein-surfactant complexes in solid form and the related precipitation processes can be slow or fast, depending on the overall solute content and the mole ratio. At high concentrations, a gel, extending on both sides of the charge neutralization line, and two-phase regions are observed. Gels shrink in open air and swell in the presence of excess water. Depending on concentration and temperature, the gels transform from an essentially liquidlike behavior to that peculiar to true gels (when G' > or = G''). The thermal gelation threshold, the temperature above which G' > or = G'', depends on BSA and NaTDC content and is concomitant to moderate heat effects, inferred by differential scanning calorimetry (DSC). The above data also indicate that the protein thermal denaturation in the gel is shifted to higher temperatures compared to water. Such a stabilizing effect is presumably related to the occurrence of both electrostatic and hydrophobic interactions with NaTDC. Water self-diffusion in the gels is slightly slower than that in the bulk and poorly sensitive to composition: it is about 65% the value of neat H2O in a wide concentration range, irrespective of the BSA, or NaTDC, concentration. A peculiar behavior is also observed in 23Na longitudinal and transverse relaxation rates. The T1 and T2 values, measured at 105.75 MHz on BSA-NaTDC gels, indicate that the motions determining the NMR relaxation of the sodium ions in the hydration layer of the protein-surfactant aggregates are not slow, having frequencies comparable with the Larmor one. The above properties, especially the rheological and the spectroscopic ones, are important for understanding the behavior of gels based on protein-surfactant mixtures. PMID:16800527

Orioni, Barbara; Roversi, Mauro; La Mesa, Camillo; Asaro, Fioretta; Pellizer, Giorgio; D'Errico, Gerardino

2006-06-22

119

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

PubMed

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

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

2012-01-01

120

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

PubMed

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

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

2014-04-01

121

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

PubMed

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

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

2011-07-01

122

Effects of structure dissymmetry on aggregation behaviors of quaternary ammonium Gemini surfactants in a protic ionic liquid EAN.  

PubMed

The aggregation behaviors of a series of dissymmetric cationic Gemini surfactants, [C(m)H(2m+1)(CH(3))(2)N(CH(2))(2)N(CH(3))(2)C(n)H(2n+1)]Br(2), designated as m-2-n (with a fixed m + n = 24, m = 16, 14, 12) have been investigated in a protic ionic liquid, ethylammonium nitrate (EAN). Surface tension, polarized optical microscopy (POM), small-angle X-ray scattering (SAXS), and rheological measurements are adopted to investigate the micellization and lyotropic liquid crystal (LLC) formation. The obtained results indicate that the structure dissymmetry plays an important role in aggregation process of m-2-n. With increasing degree of dissymmetry, the critical micellization concentration, the maximum reduction of solvent surface tension, and the minimum area occupied per surfactant molecule at the air/EAN interface all become smaller. The thermostability of formed LLCs is therefore improved because of the more compact molecules. These characteristics can be explained by the enhancement of solvophobic effect due to the increased structure dissymmetry of Gemini surfactants. PMID:23140416

Wang, Xudong; Li, Qintang; Chen, Xiao; Li, Zhihong

2012-12-01

123

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

PubMed

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

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

2009-01-01

124

Mixed surfactant systems for enhanced oil recovery  

SciTech Connect

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

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

1990-12-01

125

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

Microsoft Academic Search

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

Dan Wu; Guiying Xu; Yujun Feng; Yiming Li

2007-01-01

126

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

SciTech Connect

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

Somasundaran, Prof. P.

2002-03-04

127

Compaction of DNA by Gemini Surfactants: Effects of Surfactant Architecture  

Microsoft Academic Search

The interaction between bacteriophage T4 DNA and cationic gemini surfactants was studied by the use of fluorescence microscopy. Upon addition of surfactant, DNA undergoes a transition from random coil to globule, with an intermediate coexistence region. The state behavior of a DNA–gemini surfactant system was found to depend on spacer length, valency, head group size, and tail length. A series

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

2002-01-01

128

Solubilization of octane in electrostatically-formed surfactant-polymer complexes.  

PubMed

Polymers can be used to modulate the stability and functionality of surfactant micelles. The purpose of this study was to investigate the solubilization of an octane oil-in-water emulsion in mixtures of an anionic polymer (carboxymethyl cellulose) and anionic sodium dodecylsulphate (SDS), nonionic polyoxyethylene sorbitan monooleate (Tween 80) and cationic cetyltrimethylammonium bromide (CTAB) surfactant micelles using dynamic light scattering, microelectrophoresis and turbidity measurements. The results showed that the addition of anionic carboxymethyl cellulose accelerated octane solubilization in cationic CTAB and CTAB-Tween 80 micelles, but did not affect the solubilization behaviors of micelles that were nonionic and anionic. The surfactant-polymer interactions were also studied using isothermal titration calorimetry (ITC) to characterize different physiochemical interaction regions depending on surfactant concentration in surfactant-polymer systems. Upon octane solubilization in CTAB-carboxymethyl cellulose mixtures, shape transitions of polymer-micelle complexes may have taken place that altered light scattering behavior. Based on these results, we suggest a mechanism for oil solubilization in electrostatically-formed surfactant-polymer complexes. PMID:24407654

Zhang, Hui; Zeeb, Benjamin; Salminen, Hanna; Feng, Fengqin; Weiss, Jochen

2014-03-01

129

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

Microsoft Academic Search

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

Martin A. Bos; Ton van Vliet

2001-01-01

130

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

PubMed

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

Li, Hongguang; Hao, Jingcheng

2008-08-28

131

Double inversion of emulsions induced by salt concentration.  

PubMed

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

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

2012-05-01

132

Kenaf as a Deep-Bed Filter Medium to Remove Oil from Oil-in-Water Emulsions  

Microsoft Academic Search

This study investigated the feasibility of deep-bed filtration using kenaf (agricultural fiber) media for the removal of oil from oil-in-water emulsions. Continuous flow, constant pressure filtrations were conducted using surfactant stabilized emulsions. Removal of oil and grease varied from 70 to 95% for 500 mg\\/L oil-in-water emulsion stabilized by surfactants. Oil removal was better for larger oil drops, finer media

Bose K. Varghese; Theodore G. Cleveland

1998-01-01

133

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

PubMed

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

ElSayed, Eman M; Prasher, Shiv O

2014-03-01

134

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

PubMed

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

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

2012-06-26

135

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

NASA Astrophysics Data System (ADS)

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

Zhang, Ying; Jin, Chao

2011-01-01

136

Experimental observation and prediction of interfacial tension and viscoelastic emulsion model behavior in novel phosphate glass-polymer hybrids.  

PubMed

The interfacial tension of hybrids composed of a tin-based phosphate glass (Pglass) and thermoplastic polymers, low-density polyethylene (LDPE), polystyrene (PS), and polypropylene (PP) was investigated using pendant drop and droplet deformation methods. High surface tension values were determined for the pure Pglass and subsequently used to obtain interfacial tension values that were found to be greater than that of most polymer blends reported in the literature. Small amplitude oscillatory shear data were fitted to the Choi-Schowalter and Palierne emulsion models in order to estimate the interfacial tension and to validate the accuracy (or lack thereof) of using a polymer emulsion model on the special Pglass-polymer systems. Although some of the hybrids showed satisfactory agreement with the emulsion models, wide ranges of interfacial tensions were obtained, suggesting that a more complicated theory that explicitly takes the Pglass-polymer interactions, shape factor, and size distributions of the dispersed Pglass phase into account may be necessary for more accurate modeling of these special hybrid systems with enhanced benefits. PMID:12957585

Guschl, Peter C; Otaigbe, Joshua U

2003-10-01

137

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

138

Synthesis of TRITON™ X-based phosphate ester surfactants and their self-charring behavior  

Microsoft Academic Search

This paper describes the synthesis and characterization of a series of TRITON™ X-based surfactants with a predominantly alkyl phenol ethoxylate (APE) backbone and a phosphate ester chain end. Four phosphate-terminated TRITON™ X (or APE) derivatives (OPE2–OPO(OH)2, OPE5–OPO(OH)2, OPE10–OPO(OH)2, and NPE10–OPO(OH)2) were prepared from commercially available octyl phenol ethoxylate (OPE) of different oxyethylene units (n=2, 5 and 10), nonyl phenol ethoxylate

Tae-Hwan Kwon; Eun Sung Lee; Sang Mock Lee; Jin-Young Bae

2007-01-01

139

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

SciTech Connect

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

Somasundaran, Prof. P.

2001-02-27

140

Extraction of Phenol and Cresol by Liquid Surfactant Membrane  

Microsoft Academic Search

A model for the extraction of weak acids or weak bases by means of liquid surfactant membranes is presented in which external mass transfer around W\\/O emulsion drop, internal mass transfer inside W\\/O emulsion drop, both phase and chemical equilibria, and the drop size distribution of W\\/O emulsion are taken into account The experimental results on the batch extraction of

Masaaki Teramoto; Hiroshi Takihana; Michiru Shibutani; Takahiro Yuasa; Naotake Hara

1983-01-01

141

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

SciTech Connect

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

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

1991-07-01

142

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

PubMed

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

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

2012-03-01

143

Nanoscale and Microscale Iron Emulsions for Treating DNAPL  

NASA Technical Reports Server (NTRS)

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.

Geiger, Cherie L.

2002-01-01

144

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

NASA Astrophysics Data System (ADS)

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

Matar, Omar Kamal

145

Experimental Study of Solvent Based Emulsion Injection to Enhance Heavy Oil Recovery  

E-print Network

This study presents the results of nano-particle and surfactant-stabilized solvent-based emulsion core flooding studies under laboratory conditions that investigate the recovery mechanisms of chemical flooding in a heavy oil reservoir. In the study...

Qiu, Fangda

2011-08-08

146

Aqueous Polymer Emulsions by Chemical Modifications of Thermosetting Alternating Polyketones  

Microsoft Academic Search

Aqueous polymer emulsions were prepared by chemical modifications of thermosetting alternating pol- yketones in a one-pot reaction. Polymeric amines derived from the polyketones can act as polymeric surfactants for the self-emulsification of polyketones. The stability and structure of the emulsions with respect to the storage time at room temperature (208C) at different experimental con- ditions were thoroughly studied by dynamic

Youchun Zhang; A. A. Broekhuis; F. Picchioni

2007-01-01

147

Physico-Chemical Studies on the Interaction of Bacterial Polysaccharide- Surfactant Aggregates with Special Reference to their Hydrodynamic Behavior.  

PubMed

Capsular polysaccharides (SPS) are the integral component of gram-negative bacteria, and also have potential uses as vaccines. In this paper, interaction of anionic SPS, isolated from Klebsiella K28, K43, K51 and K20, with cationic surfactants and cationic-nonionic mixed surfactants were investigated by turbidimetric titration, viscometric method. Variation of size and zeta-potential was measured using dynamic light scattering method. Due to binding of the surfactants size enhancement and charge reversal takes place. The interaction between oppositely charged polymer-surfactants are governed by the nature of the charged head group and of the counter ion, charge density and rigidity of the polymer architecture, CMC of the surfactant systems, concentration of surfactant (Cs). The binding is influenced both by electrostatic and hydrophobic interaction. PMID:25213448

Dasgupta, Satwati; Nath, Ranendu Kumar; Manna, Kaushik; Mitra, Ashish; Panda, Amiya Kumar

2014-10-01

148

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. ...

149

Chain length mismatch and packing effects on the thermotropic phase behavior of salt-free catanionic surfactants.  

PubMed

Thermotropic liquid crystal formation by salt-free catanionic surfactants (alkyltrimethylammonium alkylsulfonates, herein designated as TAmSon) has been investigated as a function of chain length mismatch (asymmetry). Previous studies on these compounds have revealed an unusual and rich asymmetry-dependent lyotropic phase behavior. Herein, phase transition temperatures and transition enthalpies/entropies were determined by differential scanning calorimetry, while mesophases were assigned by polarized light microscopy. Three series of compounds were investigated, namely: the TA16Son series, where n=6-10; the TAmSo8 series, where m=12-16; and a constant m+n series, TAmSon where m+n=22. Typically, several solid phases and two smectic mesophases are found prior to isotropization to the liquid phase. As asymmetry decreases, two somewhat counterintuitive tendencies emerge: a general decrease in enthalpy/entropy for solid-solid and solid-first mesophase transitions, and an increase in solid-first mesophase transition temperatures. Yet, solid phases are seen to be more stable for the most asymmetric compounds, while the second mesophase is more stable for the least asymmetric ones, in what appears to be a more complex behavior than expected. The results are globally interpreted in terms of subtle differences in chain interdigitation and packing, and odd-even chain effects. PMID:23769304

Matos, Marta R A; Silva, Bruno F B; Marques, Eduardo F

2013-09-01

150

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

PubMed

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

Piculell, Lennart

2013-08-20

151

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

Microsoft Academic Search

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

A. I Zouboulis; A Avranas

2000-01-01

152

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

SciTech Connect

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

Prof. P. Somasundaran

2002-09-30

153

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

PubMed

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

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

2014-10-15

154

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

PubMed

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

Kim, Young Dae

2001-04-15

155

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

SciTech Connect

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

Prof. P. Somasundaran

2003-03-31

156

Emulsion Paint of Aromatic Petroleum Resin. I. Emulsification of Aromatic Petroleum Resin Solution in Water  

Microsoft Academic Search

Industrial emulsification of an aromatic petroleum resin solu tion in bodied linseed oil was investigated using an emulsion inversion process. It was found that the preferred surfactant had the best match in solubility parameter between olefinic group and resin solution A slight variation was found in optimum H LB for emulsification, depending on the chemical family of surfactants chosen, but

Yoshiyuki Iwase

1980-01-01

157

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

PubMed

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

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

2009-06-15

158

In vitro evaluation of floating and drug releasing behaviors of hollow microspheres (microballoons) prepared by the emulsion solvent diffusion method.  

PubMed

Hollow microspheres (microballoons) floatable in JPX III No.1 solution were developed as a dosage form characterized by excellent buoyant properties in the stomach. Microballoons were prepared by the emulsion solvent diffusion method utilizing enteric acrylic polymers codissolved with drug in a mixture of dichloromethane and ethanol. The release properties of five different drugs exhibiting distinct water solubilities (aspirin, salicylic acid, ethoxybenzamide, indomethacin and riboflavin) entrapped within microballoons were investigated. Buoyancy of the microballoons decreased with increasing drug release rate. In the case of aspirin, salicylic acid and ethoxybenzamide, the drug release profiles of microballoons proved a linear relationships by Higuchi plotting. However, indomethacin and riboflavin release profiles did not follow the Higuchi equation. When the loading amount of riboflavin was higher than the solubility in the mixture of dichloromethane and ethanol, the drug release profiles of the microballoons displayed an initial burst release. The insoluble riboflavin in the mixture of dichloromethane and ethanol adsorbed on to the microballoon surface in the crystal state. Such riboflavin crystals were released preferentially at the initial stage of the release test, which was attributable to the initial burst. In addition, by incorporating a polymer such as hydroxypropylmethylcellulose within the shell of microballoons, the release rate of riboflavin from the microballoons could be controlled while maintaining high buoyancy. PMID:15018980

Sato, Yasunori; Kawashima, Yoshiaki; Takeuchi, Hirofumi; Yamamoto, Hiromitsu

2004-03-01

159

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

PubMed

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

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

2014-08-01

160

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

161

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

Microsoft Academic Search

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

Mukund Vasudevan; Amy Shen; Bamin Khomami; Radhakrishna Sureshkumar

2008-01-01

162

Cleavable surfactants  

Microsoft Academic Search

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

Per-Erik Hellberg; Karin Bergström; Krister Holmberg

2000-01-01

163

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

PubMed

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

Rao, Jiajia; McClements, David Julian

2011-05-11

164

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

PubMed

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

Kim, Young Dae; Nam, Suk Woo

2004-01-01

165

Emulsion design to improve the delivery of functional lipophilic components.  

PubMed

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

McClements, David Julian

2010-01-01

166

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

SciTech Connect

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

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

1996-01-01

167

Influence of ionic and nonionic hydrotropes on micellar behavior of a cationic gemini surfactant butanediyl-1,4-bis(dimethylcetylammonium bromide).  

PubMed

Micellization of binary systems of a cationic gemini surfactant butanediyl-1,4-bis(dimethylcetylammonium bromide) (16-4-16) and cationic/nonionic hydrotropes (aniline-hydrochloride, 2-methylanilinehydrochloride, 4-methylanilinehydrochloride, hydroxybenzene, 1,3-benzenediol, benzene-1,2,3-triol) have been studied using a conductometric technique. The critical micelle concentrations (cmc) for different mixing mole fractions at different temperatures have been calculated. To explain and compare the results, theoretical models of Clint, Rubingh and Motomura have been used to obtain the ideal cmc, mixed micelle composition, interaction parameters (?(m)), free energies of micellization, and activity coefficients. The mixtures show nonideal behavior and the interactions between the surfactants and the hydrotropes are synergistic in nature which is confirmed by high negative ?(m) values and low values of the activity coefficients. Thermodynamic parameters were also obtained from the temperature dependence of the cmc values. PMID:21531427

Khan, Iqrar Ahmad; Khanam, Ahmad Jahan; Sheikh, Mohmad Shafi; Kabir-ud-Din

2011-07-15

168

Flow of Super-Concentrated Emulsions  

NASA Astrophysics Data System (ADS)

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

Masalova, Irina; Malkin, Alexander Ya.

2006-05-01

169

Decompressing emulsion droplets favors coalescence.  

PubMed

The destabilization process of an emulsion under flow is investigated in a microfluidic device. The experimental approach enables us to generate a periodic train of droplet pairs, and thus to isolate and analyze the basic step of the destabilization, namely, the coalescence of two droplets which collide. We demonstrate a counterintuitive phenomenon: coalescence occurs during the separation phase and not during the impact. Separation induces the formation of two facing nipples in the contact area that hastens the connection of the interfaces prior to fusion. Moreover, droplet pairs initially stabilized by surfactants can be destabilized by forcing the separation. Finally, we note that the fusion mechanism is responsible for a cascade of coalescence events in a compact system of droplets where the separation is driven by surface tension. PMID:18232876

Bremond, Nicolas; Thiam, Abdou R; Bibette, Jérôme

2008-01-18

170

Gemini surfactants  

Microsoft Academic Search

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

Milton J. Rosen; David J. Tracy

1998-01-01

171

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

SciTech Connect

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

Sar, B.

1992-12-31

172

Micelle formation and CMC of gemini surfactants: a thermodynamic model  

Microsoft Academic Search

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

Terri A. Camesano; R. Nagarajan

2000-01-01

173

Interaction of nonionic surfactant AEO9 with ionic surfactants*  

PubMed Central

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

Zhang, Zhi-guo; Yin, Hong

2005-01-01

174

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

PubMed

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

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

2012-10-01

175

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

PubMed

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

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

2011-02-15

176

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

Microsoft Academic Search

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

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

2012-01-01

177

Cationic bituminous emulsions and emulsion aggregate slurries  

SciTech Connect

A cationic bituminous emulsion is described which consists of from about 30% to about 80% by weight of bitumen, from about 0.1% to about 10% by weight of an emulsifier selected from the group consisting of reaction products of a polyamine reacted with a member of the group consisting of epoxidized unsaturated fatty acids of chain lengths between C/sub 8/ and C/sub 22/ and the esters thereof and adding water to make up 100% by weight, the emulsion having a pH in the range of from 2-7.

Schilling, P.

1986-07-01

178

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

SciTech Connect

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.

Prof. P. Somasundaran

2002-03-01

179

Effect of glycyl dipeptides on the micellar behavior of gemini surfactant: A conductometric and fluorescence spectroscopic study  

Microsoft Academic Search

The effect of glycyl dipeptides (glycylglycine, glycyl-L-valine, and glycyl-L-leucine) on the micellar properties of gemini surfactant pentamethylene-1,5-bis(dodecyldimethylammonium bromide) (12-5-12) has been investigated by means of conductivity and fluorescence spectroscopy. The results obtained from conductivity show that the effect of glycyl dipeptides depends upon their nature and concentration, as well as the temperature. The values of critical micelle concentration (cmc) of

Zhenning Yan; Yu Li; Xiaolan Wang; Junying Dan; Jianji Wang

2011-01-01

180

Facile fabrication of biocompatible PLGA drug-carrying microspheres by O\\/W pickering emulsions  

Microsoft Academic Search

This study is focused on the preparation of Ibuprofen (IBU) loaded micrometer-sized poly(lactic-co-glycolic acid) (PLGA) microspheres and process variables on the size, drug loading and release during preparation of formulation. Silicon dioxide (SiO2) nanoparticle-coated PLGA microspheres were fabricated via a combined system of “Pickering-type” emulsion route and solvent volatilization method in the absence of any molecular surfactants. Stable oil-in-water emulsions

Zengjiang Wei; Chaoyang Wang; Hao Liu; Shengwen Zou; Zhen Tong

181

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

Microsoft Academic Search

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

Noa Cohen; Michael S. Silverstein

2011-01-01

182

Preparation of colloidal silica from sodium metasilicate solution and sulphuric acid in emulsion medium  

Microsoft Academic Search

The studies were directed toward production of silicas from emulsion systems. Precipitation of colloidal silica from sodium metasilicate solution was performed using sulphuric acid. Optimum emulsion composition and precipitation parameters were worked out. As emulsifiers non-ionic surfactants were used (Rokafenol N-5, N-6 and N-9). Moreover, basic physicochemical parameters of obtained silicas were evaluated. Surface character (zeta potential) was examined by

Teofil Jesionowski

2001-01-01

183

Droplet-based microfluidics and the dynamics of emulsions  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

184

Phase Behavior and Emulsion Stability of the Aot/Decane/ Water/NaCl System at Very Low Volume Fractions of Oil  

E-print Network

The stability of a ternary system composed of decane/water/Aerosol-OT and salt is revisited. Phase diagrams and emulsions similar in composition to those previously studied by Hofman and Stein [Hofman, 1991] were made. Ac- cording to our results, and contrary to the common experience, these systems exhibit a maximum of stability very close to the balance zone.

Yithanllili Bastidas; Lisset Hernaandez; Issarly Rivas; Kareem Rahn-Chique; German Urbina-Villalba

2014-10-09

185

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

PubMed

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

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

2008-11-01

186

Physical properties of emulsion-based hydroxypropyl methylcellulose films: effect of their microstructure.  

PubMed

The initial characteristics of emulsions and the rearrangement of the oil droplets in the film matrix during film drying, which defines its microstructure, has an important role in the physical properties of the emulsion-based films. The objective of this work was to study the effect of the microstructure (two droplet size distributions) and stability (with or without surfactant) of HPMC oil-in-water emulsions over physical properties of HPMC emulsion-based edible films. HPMC was used to prepare sunflower oil-in-water emulsions containing 0.3 or 1.0% (w/w) of oil with or without SDS, as surfactant, using an ultrasonic homogenizer. Microstructure, rheological properties and stability of emulsions (creaming) were measured. In addition, microstructure, coalescence of oil droplets, surface free energy, optical and mechanical properties and water vapor transfer of HPMC films were evaluated. Image analysis did not show differences among droplet size distributions of emulsions prepared at different oil contents; however, by using SDS the droplet size distributions were shifted to lower values. Volume mean diameters were 3.79 and 3.77 ?m for emulsions containing 0.3 and 1.0% without surfactant, respectively, and 2.72 and 2.71 ?m for emulsions with SDS. Emulsions formulated with 1.0% of oil presented higher stability, with almost no change during 5 and 3 days of storage, for emulsions with and without SDS, respectively. Internal and surface microstructure of emulsion-based films was influenced by the degree of coalescence and creaming of the oil droplets. No effect of microstructure over the surface free energy of films was found. The incorporation of oil impaired the optical properties of films due to light scattering of light. Addition of oil and SDS decreased the stress at break of the emulsion-based films. The replace of HPMC by oil and SDS produce a lower "amount" of network structure in the films, leading to a weakening of their structure. The oil content and SDS addition had an effect over the microstructure and physical properties of HPMC-based emulsions which lead to different microstructures during film formation. The way that oil droplets were structured into the film had an enormous influence over the physical properties of HPMC films. PMID:22840052

Zúñiga, R N; Skurtys, O; Osorio, F; Aguilera, J M; Pedreschi, F

2012-10-01

187

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

SciTech Connect

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

Somasundaran, Prof. P.

2001-04-04

188

Structures of octenylsuccinylated starches: effects on emulsions containing ?-carotene.  

PubMed

Starches with different amylopectin contents and different molecular sizes prepared using acid hydrolysis were hydrophobically modified using octenylsuccinic anhydride (OSA). The OSA-modified starches were used as surfactants to stabilize emulsions of ?-carotene and canola oil dispersed in water. The objective of this study is to investigate the relationship between starch molecular structure and the chemical stability of the emulsified ?-carotene, as well as the colloidal stability of emulsion droplets during storage. The oil droplet size in emulsions was smaller when starch had (a) lower hydrodynamic volume (Vh) and (b) higher amylopectin content. The oxidative stability of ?-carotene was similar across samples, with higher results at increased amylopectin content but higher Vh. Steric hindrance to coalescence provided by adsorbed OSA-modified starches appears to be improved by more rigid molecules of higher degree of branching. PMID:25129720

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

2014-11-01

189

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

PubMed

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

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

2013-11-15

190

Flotation of coal with latex emulsions of hydrocarbon animal or vegetable based oil  

SciTech Connect

Employment of a latex emulsion prepared from a hydrocarbon, animal or vegetable based oil with a hydrophobic water-in-oil emulsifier and a hydrophilic surfactant in the froth flotation of coal improves coal recovery without increasing the ash content. The emulsifier employed should have an hlb value of 5.0 or less while the surfactant should have an hlb value of 9.0 or higher.

Scanlon, M.J.; Wang, S.S.

1982-07-20

191

Fluoropolymer-Based Emulsions for the Intravenous Delivery of Sevoflurane  

PubMed Central

Background The intravenous delivery of halogenated volatile anesthetics has been previously achieved using phospholipid-stabilized emulsions, e.g. Intralipid. However, fluorinated volatile anesthetics, such as sevoflurane, are partially fluorophilic and do not mix well with classic non-fluorinated lipids. This effect limits the maximum amount of sevoflurane that can be stably emulsified in Intralipid to 3.5% v/v. This is a significant limitation to the potential clinical use of Intralipid-based emulsions. Methods The authors prepared a 20% v/v sevoflurane emulsion using a novel fluorinated surfactant and tested its effectiveness and therapeutic index by administering it to male Sprague-Dawley rats via intravenous injection into the jugular vein. The median effective dose to induce anesthesia (ED50), median lethal dose (LD50), and therapeutic index (LD50 / ED50) were determined. Anesthesia was measured by loss of the forepaw righting reflex. Results The ED50 and LD50 values were found to be 0.41 and 1.05 mL emulsion / kg body weight, respectively. These lead to a therapeutic index of 2.6, which compares favorably to previously determined values of emulsified isoflurane, as well as values for propofol and thiopental. Conclusions A novel semi-fluorinated surfactant was able to considerably increase the maximum amount of stably emulsified sevoflurane compared to Intralipid. These formulations can be used to rapidly induce anesthesia with bolus dosing from which recovery is smooth and rapid. PMID:18813044

Fast, Jonathan P.; Perkins, Mark G.; Pearce, Robert A.; Waters, Ralph M.; Mecozzi, Sandro

2009-01-01

192

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

193

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

PubMed Central

Mild non-ionic sucrose ester surfactants can be employed to produce lipid-based drug delivery systems for dermal application. Moreover, sucrose esters of intermediate lipophilicity such as sucrose stearate S-970 possess a peculiar rheological behavior which can be employed to create highly viscous semi-solid formulations without any further additives. Interestingly, it was possible to develop both viscous macroemulsions and fluid nanoemulsions with the same chemical composition merely by slight alteration of the production process. Optical light microscopy and cryo transmission electron microscopy (TEM) revealed that the sucrose ester led to the formation of an astonishing hydrophilic network at a concentration of only 5% w/w in the macroemulsion system. A small number of more finely structured aggregates composed of surplus surfactant were likewise detected in the nanoemulsions. These discoveries offer interesting possibilities to adapt the low viscosity of fluid O/W nanoemulsions for a more convenient application. Moreover, a simple and rapid production method for skin-friendly creamy O/W emulsions with excellent visual long-term stability is presented. It could be shown by franz-cell diffusion studies and in vitro tape stripping that the microviscosity within the semi-solid formulations was apparently not influenced by their increased macroviscosity: the release of three model drugs was not impaired by the complex network-like internal structure of the macroemulsions. These results indicate that the developed semi-solid emulsions with advantageous application properties are highly suitable for the unhindered delivery of lipophilic drugs despite their comparatively large particle size and high viscosity. PMID:24310496

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

2011-01-01

194

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

PubMed

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

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

2014-10-01

195

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

PubMed

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

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

2006-11-15

196

Reversible pH- and Photocontrollable Carbohydrate-Based Surfactants.  

PubMed

The parallel synthesis and properties of a library of photoswitchable surfactants comprising a hydrophobic butylazobenzene tail-group and a hydrophilic carbohydrate head-group, including the first surfactants to exhibit dual photo- and pH-responsive behavior, is reported. This new generation of surfactants shows varying micelle morphologies, photocontrollable surface tension, and pH-induced aggregation and adsorption. PMID:25212733

Tabor, Rico F; Tan, David D; Han, Sean S; Young, Scott A; Seeger, Zoe L E; Pottage, Matthew J; Garvey, Christopher J; Wilkinson, Brendan L

2014-10-20

197

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

Microsoft Academic Search

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

P. Babadur; S. N. Srivastava

1975-01-01

198

Emulsions from Aerosol Sprays  

PubMed

An electrostatic emulsification apparatus has been designed for the purpose of studying diffusion from oil droplets which have a mean size in the range of approximately 1.5-3.5 &mgr;m, with standard deviations of 40-50%. The emulsification technique involves the collection of a spray of electrically charged oil droplets onto a rotating water film which is sustained from a reservoir. In this way, emulsions with volume fractions of approximately 10(-3) are produced within several minutes at oil flow rates of around 10(-2) ml min-1. Phase-Doppler anemometry (PDA) was used to assess droplet size distributions for the sprays and emulsions. Results show that the mean emulsion droplet size was smaller than the mean spray droplet size by several orders of magnitude. At flow rates around 10(-2) ml min-1, the spray droplet size distribution was little affected by the applied potential between about -4.20 and -4.65 kV (mean droplet size between approximately 7.6 and 7.8 &mgr;m, with standard deviations of approximately 20%), whereas the mean droplet size of the corresponding emulsion decreased more rapidly with applied potential. Above an applied potential of approximately -4.30 kV, which corresponded to an emulsion droplet size below approximately 2 &mgr;m, the measured volume fraction of the emulsion decreased with respect to the volume fraction as calculated on the basis of total amount of injected oil. Copyright 1997 Academic Press. Copyright 1997Academic Press PMID:9441645

Hengelmolen; Vincent; Hassall

1997-12-01

199

Surface shear inviscidity of soluble surfactants  

PubMed Central

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

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

2014-01-01

200

Separation of cobalt and nickel by liquid surfactant membranes containing a synthesized cationic surfactant  

SciTech Connect

Separation of cobalt(II) and nickel(II) by using a hydroxyoxime extractant has been investigated both in liquid-liquid equilibrium extraction studies, hydroxyoximes showed significant extractability for nickel ions, although LIX 84 was found to have exceptional chelating affinity for nickel ions. In the LSM system functionalized by hydroxyoxime, the cobalt ions were efficiently separated from nickel ions as a result of slower permeation of nickel chelates across the emulsion membrane. More complete cobalt recovery was achieved in the LSMs dosed with LIX 860 than when the same carrier was applied to the liquid-liquid extraction system. Furthermore, cobalt permeation rate was enhanced threefold when a quaternary ammonium type of cationic surfactant was used as an emulsifier due to carrier interaction with surfactant at the reaction interface. The permeation mechanism of ions in LSMs was elucidated by an interfacial reaction model which took into account the adsorption of the carrier and surfactant at the reaction interface.

Kakoi, Takahiko; Ura, Tsuyoshi; Kasaini, H.; Goto, Masahiro [Kyushu Univ., Fukuoka (Japan). Dept. of Chemical Science and Technology; Nakashio, Fumiyuki [Kumamoto Inst. of Tech., Ikeda (Japan). Dept. of Industrial Chemistry

1998-06-01

201

Adsorption behavior of light green anionic dye using cationic surfactant-modified wheat straw in batch and column mode.  

PubMed

An agricultural by-product, natural wheat straw (NWS), was soaked in 1 % cationic surfactant (hexadecylpyridinium bromide, CPB) solution for 24 h (at 293 K), and modified wheat straw (MWS) was obtained. Analysis of FTIR, XFR, and nitrogen element showed that CPB was adsorbed onto surface of NWS. Then, MWS was used as adsorbent for the removal of light green dye (LG, anionic dye) from aqueous solution. The experiment was performed in batch and column mode at room temperature (293 K). Sodium chloride (up to 0.1 mol/L) existed in solution was not favor of LG dye adsorption. The equilibrium data were better described by Langmuir isotherm, and adsorption capacity of q m from Langmuir model was 70.01 ± 3.39 mg/g. In fixed-bed column adsorption mode, the effects of initial LG concentration (30, 50, 70 mg/L) and flow rate (6.5, 9.0, 14.5 mL/min) on adsorption were presented. Thomas and modified dose-response models were used to predict the breakthrough curves using nonlinear analysis method, and both models can fit the breakthrough curves. Theoretical and experimental breakthrough curves were drawn and compared. The results implied that MWS can be used as adsorbent material to remove LG from aqueous solution. PMID:23440440

Su, Yinyin; Zhao, Binglu; Xiao, Wei; Han, Runping

2013-08-01

202

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

NASA Astrophysics Data System (ADS)

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

Gurevich, Leonid; Fojan, Peter

2012-02-01

203

Improved control over particle sizes and stability of concentrated fluorocarbon emulsions by using mixed fluorocarbon/hydrocarbon molecular dowels.  

PubMed

The use of a surfactant system consisting in equimolar amounts of egg yolk phospholipids and of a mixed fluorocarbon/hydrocarbon amphiphile (C8H17CH = CHC8F17) allows the preparation of concentrated (90% w/v, i.e. 47% v/v) emulsions of perfluorooctyl bromide (perflubron), with average particle sizes ranging from 0.12 to 16 microns post-sterilization, depending on the surfactant/fluorocarbon ratio. Emulsion droplet diameters varied linearly as a function of the emulsifier's concentration, thus allowing easy pre-determination of the emulsion's average particle size. Excellent stability was observed for the dowel-containing emulsions for at least 6 months at 40 degrees C over the whole domain of particle sizes investigated. PMID:7849921

Cornélus, C; Krafft, M P; Riess, J G

1994-01-01

204

Using Nanotechnology in Viscoelastic Surfactant Stimulation Fluids  

E-print Network

Viscoelastic surfactant (VES) fluids are preferred for many applications in the oil industry. Their viscoelastic behavior is due to the overlap and entanglement of very long wormlike micelles. The growth of these wormlike micelles depends...

Gurluk, Merve Rabia 1986-

2012-11-12

205

Chemical demulsification of petroleum emulsions using oil-soluable demulsifiers  

Microsoft Academic Search

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

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

1991-01-01

206

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

PubMed

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

Nikolakakis, Ioannis; Malamataris, Stavros

2014-05-01

207

Multi-enzyme immobilization in eco-friendly emulsion liquid membrane reactor—a new approach to membrane formulation  

Microsoft Academic Search

Multi-enzymes (?-glucosidase and glucose oxidase) have been immobilized in emulsion liquid membranes for using such membranes as eco-friendly enzyme emulsion liquid membrane (EELM) reactors. Role of surfactant-stabilized liquid membranes as separation-concentration devices changes here to that of promising, eco-friendly reactors where product is transported to the external phase thereby eliminating the need for demulsification for subsequent recovery of product and

P. Pal; S. Datta; P. Bhattacharya

2002-01-01

208

Surfactant flooding solution  

SciTech Connect

An aqueous treating solution is disclosed for surfactant flooding operations to increase oil recovery. The treating solution comprises water, one or more surfactants, one or more solubilizers and a sulfonated dicyclopentadiene compound which permits a reduction in the needed quantities of surfactant and solubilizer without loss of surfactant stability and activity or oil recovery efficiency.

Schievelbein, V.H.; Zabczuk, P.

1984-03-20

209

DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS  

SciTech Connect

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

Kishore K. Mohanty

2003-07-01

210

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

SciTech Connect

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

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

2010-01-01

211

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

PubMed

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

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

2014-11-18

212

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

NASA Astrophysics Data System (ADS)

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

Prokopov, Nikolai I.; Gritskova, Inessa A.

2001-09-01

213

Double Emulsion Templated Celloidosomes  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

214

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

NASA Astrophysics Data System (ADS)

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

Sung, Meagan

215

On formulating ophthalmic emulsions.  

PubMed

The formulation of dilute, transparent ophthalmic emulsions (eye drops) with long shelf lives is a challenge because of the tendency of the emulsion droplets to aggregate, particularly in the presence of the water-soluble polymers typically used in eye drops. While many functions of eye drops, such as lubricity and residence time in the eye, are promoted by high concentrations of high molecular weight water-soluble polymers, emulsified lipids and drugs aggregate in the eye drop bottle if the polymer concentration is above the critical flocculation concentration (CFC). The purpose is to develop a simple approach to predict the CFC for polymers based on information readily available in the literature. High molecular weight guar was hydrolyzed to give a series of guar samples spanning a wide range of average molecular weights. The CFC values and critical viscosity concentrations were measured as functions guar properties, using electrophoresis, dynamic light scattering and rheology measurements. The higher the guar molecular weight, the lower was the CFC, the maximum concentration that can be tolerated in the eye drop formulation. The guar CFC values were approximately equal to the overlap concentrations where guar molecules start to overlap in solution. We propose that the CFC can be estimated for any water-soluble polymer using the polymer molecular weight and the readily available Mark-Houwink parameters, thus providing a design rule for ophthalmic emulsions. PMID:25016540

Mafi, Roozbeh; Gray, Cameron; Pelton, Robert; Ketelson, Howard; Davis, James

2014-10-01

216

Amphoteric water-in-oil self-inverting polymer emulsion  

SciTech Connect

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

Lipowski, S. A.

1985-11-12

217

Chemical flooding of oil reservoirs 5. The multiphase behavior of oil\\/brine\\/surfactant systems in relation to changes in pressure, temperature, and oil composition  

Microsoft Academic Search

Multiphase PVT-studies are conducted on surfactant-brine-oil systems relevant for oil recovery processes. An alkyl-o-xylene sulfonate is used as surfactant, NaCl-solution as brine, and various types of live oil, i.e. crude oil, fraction of crude oil, and model oil. Solubilization parameters for the microemulsion phase are determined in the temperature range of 40–180°C and the pressure range of 200–1000 bar. By

Tor Austad; Helge Hodne; Skule Strand; Kirsti Veggeland

1996-01-01

218

Adsorption of Gemini surfactants onto clathrate hydrates.  

PubMed

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

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

2013-12-15

219

Micellization of true amphoteric surfactants.  

PubMed

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

Li, Yunxiang; Holmberg, Krister; Bordes, Romain

2013-12-01

220

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

PubMed

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

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

2014-10-13

221

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

PubMed

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

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

2013-07-15

222

Status of surfactants as penetration enhancers in transdermal drug delivery.  

PubMed

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

Som, Iti; Bhatia, Kashish; Yasir, Mohd

2012-01-01

223

Status of surfactants as penetration enhancers in transdermal drug delivery  

PubMed Central

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

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

2012-01-01

224

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

E-print Network

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

Mendenhall, Jonathan David

2012-01-01

225

Surfactant Diffusion into Lysozyme Crystal Matrices Investigated by Quantitative Fluorescence Microscopy  

E-print Network

and surfactants and are relevant to protein purification and crystallization and to the manipulation of proteins. These measurements are extended to mo- lecular-level events by probing how the behavior of the surfactants

Velev, Orlin D.

226

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

PubMed

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

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

2011-10-01

227

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

228

Surfactants and subsurface remediation  

Microsoft Academic Search

Because of the limitations of pump-and-treat technology, attention is now focused on the feasibility of surfactant use to increase its efficiency. Surfactants have been studied for use in soil washing and enhanced oil recovery. Although similarities exist between the applications, there are significant differences in the objectives of the technologies and the limitations placed on surfactant use. In this article

Candida C. West; Jeffrey H. Harwell

1992-01-01

229

Effect of grafting architecture on the surfactant-like behavior of clay-poly(NiPAAm) nanohybrids.  

PubMed

A new class of clay-polymer nanohybrids was synthesized by grafting poly(N-isopropylacrylamide) (PNiPAAm) on the edge of nanoscale silicate platelets (NSPs) through covalently bonded linkers to form various architectures. The inherent ionic character of NSPs and the organic moieties of isopropyl amide in PNiPAAms impart surface active properties to the nanohybrids. Surface tension and particle size measurements were used to determine the critical micelle concentrations (CMCs) of the nanohybrids. It was found that PNiPAAm brushes grafted onto NSPs with the single-headed linkers are loosely packed and can expand easily in water causing inter-hybrid interactions. In contrast, PNiPAAm brushes grafted onto NSPs with the double-headed linkers may alternatively exhibit intra-hybrid interactions and the hybrids tend to exist in a dispersed state. Consequently, the latter has a higher CMC than the former. In addition, the CMC can be tailored by adjusting the grafting density of the linkers on the NSP surfaces. The densely grafted nanohybrids exhibit close inter-hybrid contact resulting in a lower CMC than that for the sparsely grafted nanohybrids. Molecular simulations were also performed to study the effects of the polymer-grafted architecture and the density of the linkers on the micellar behavior of NSP-PNiPAAm hybrids. The simulation results were found to be in good agreement with the experimental observations. Thus, it is possible to control the surface active properties and aggregation of the clay-PNiPAAm hybrids by manipulating the organic grafting architectures of the silicate platelets. PMID:22939253

Lin, Hsiao-Chu; Hsieh, Bi-Zen; Lin, Yung-Lung; Sheng, Yu-Jane; Lin, Jiang-Jen

2012-12-01

230

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

PubMed

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

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

2011-08-01

231

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

Microsoft Academic Search

While there is a growing body of literature on nanostructured materials made by reverse microemulsion methods, there is little information on how the surfactants used to create these emulsions affect the final chemical properties of these nanoparticles. For catalytic applications, this residue can block active sites, which can have detrimental effects on reactivity. We have used thermogravimetric analysis, XPS, XRD,

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

2007-01-01

232

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

PubMed

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

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

2002-05-15

233

Quantitative approach to ultrasonic emulsion separation.  

PubMed

Ultrasound of 2 MHz was irradiated to the emulsion prepared from canola oil and water and flocculation of the oil droplets occurred immediately. By putting the emulsion sample in a thin glass cell and setting it in bath type irradiation equipment, the progress of the separation was quantitatively monitored with the optical absorbance. The use of the cell enables visual observation of the behavior of oil droplets. Pictures show the formation of flocks of the dispersed phase and the appearance of checkered pattern consisting of flocks at a regular interval. The observation indicates that the action of radiation forces on oil droplets, which causes the flocculation. The flocks started to rise after stopping irradiation with holding their shape. The rising rate of the flocks was significantly greater than that of oil droplets in the original emulsion. Ultrasonic irradiation caused a rapid decrease in the absorbance, which expresses a progress of the separation. Effects of two major operation parameters, power and time on the separation degree were examined. The degree improved with increasing power input and irradiation time. The dataset was arranged in a plot of normalized separation degree against the input energy. The plot suggests that effective separation was attained with a lower power input and a longer irradiation time. The plot provides a guide for setting condition for the separation. PMID:18725183

Nii, Susumu; Kikumoto, Shunsuke; Tokuyama, Hideaki

2009-01-01

234

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

NASA Astrophysics Data System (ADS)

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

Wang, Xinbo; Zhang, Zhicheng

2006-09-01

235

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

Microsoft Academic Search

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

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

2001-01-01

236

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

PubMed

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

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

2013-02-13

237

DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS  

SciTech Connect

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

Kishore K. Mohanty

2003-07-01

238

The Biophysical Function of Pulmonary Surfactant  

PubMed Central

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

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

2008-01-01

239

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

PubMed

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

Meshulam, Dafna; Lesmes, Uri

2014-01-01

240

Emulsions and microemulsions with a fluorocarbon phase  

Microsoft Academic Search

A phase III clinical study of a perfluorooctyl bromide emulsion demonstrated reduction and avoidance of donor blood transfusion in surgery. Novel fluorocarbon-in-water emulsions are being investigated, including emulsions highly stabilized by fluorocarbon–hydrocarbon diblocks and targeted emulsions for molecular imaging, diagnosis and drug delivery. Reverse water-in-fluorocarbon emulsions and microemulsions that have potential for pulmonary drug delivery are also being studied. Microemulsions

Marie Pierre Krafft; Alba Chittofrati; Jean G Riess

2003-01-01

241

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

DOEpatents

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

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

1980-08-20

242

Destabilisation of oil–water emulsions and separation by dissolved air flotation  

Microsoft Academic Search

The roles of aluminium and ferric sulphates as destabilising agents for oil–water emulsions that have been stabilised by a non-ionic surfactant (Span 20) are investigated in terms of oil removal. The effects of coagulant dose, pH, and the duration and intensity of both slow and fast mixing are considered. Electrokinetic measurements indicate that oil droplets have a negative zeta potential

A. A. Al-Shamrani; A. James; H. Xiao

2002-01-01

243

Effects of Osmotic Pressure on Water Transport in W 1\\/O\\/W 2 Emulsions  

Microsoft Academic Search

In a W1\\/O\\/W2 double-emulsion globule, when the W1 phase was made of pure water while salt (NaCl) was present only in the W2 phase, water was transported from W1 to W2 at a constant transport rate, ?dR\\/dt. In the case of hydrated-surfactant transport, rates rose linearly with increasing salt concentration in W2 through acceleration of the dehydration process of the

Lixiong Wen; Kyriakos D. Papadopoulos

2001-01-01

244

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

PubMed

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

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

2014-02-01

245

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

PubMed

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

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

2014-07-22

246

Rheology and flow of water-in-oil emulsions in porous media  

SciTech Connect

The objective of this study was to determine the effects of injected drop size distribution, volume fraction of the dispersed phase, and emulsifier concentration on the flow of water-in-oil emulsions in porous media. Experiments were conducted with a model emulsion system comprising a synthetic mineral oil, deionized water, and a non-ionic surfactant. Bulk rheological properties of the emulsions were measured with a Couette flow viscometer. The drop size distributions were measured from optical micrographs using an image analysis technique. Flow tests were carried out in a sand pack. A microwave attenuation technique was employed to measure in situ water saturation. Experimental data collected in the flow tests included: measurements of pressure drop across the sand pack at different flow rates; in situ water saturation at a fixed location in the sand pack; and changes in the drop size distribution resulting from the flow through a porous medium.

Woo, R.; Jackson, C.; Maini, B.B. [Petroleum Recovery Institute, Calgary, Alberta (Canada)] [and others

1995-12-31

247

Clay Modification and Nanocomposite Fabrication with Controlled Polymer/Surfactant  

NASA Astrophysics Data System (ADS)

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

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

2001-03-01

248

Phytosterol colloidal particles as Pickering stabilizers for emulsions.  

PubMed

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

Liu, Fu; Tang, Chuan-He

2014-06-01

249

Microdisk fabrication by emulsion evaporation  

E-print Network

dedecyl sulfate (SDS). The monodisperse chloroform emulsions, generated by the glass-based microfluidic devices, ensure the precise control on microdisk particle size and shape. A systematic investigation was performed to study the relation between...

Wong, Susanna Wing Man

2007-09-17

250

Invert emulsion well servicing fluids  

SciTech Connect

An invert emulsion well servicing fluid containing an oleaginous phase, an aqueous phase, an invert emulsifier and an effective amount of a solid, particulate polyolefin having a density of about 0.90 gms/cc or greater.

Carnicom, W.M.

1982-03-13

251

Self-assembly formation of palm-based esters nano-emulsion: A molecular dynamics study  

NASA Astrophysics Data System (ADS)

Palm-oil esters (POEs) are unsaturated and non-ionic esters that can be prepared by enzymatic synthesis from palm oil. Their nano-emulsion properties possess great potential to act as drug carrier for transdermal drug delivery system. A ratio of 75:5:20 (water/POEs/Span20) was chosen from homogenous region in the phase diagram of our previous experimental work to undergo molecular dynamics simulation. A 15 ns molecular dynamics simulation of nano-emulsion system (water/POEs/Span20) was carried out using OPLS-AA force field. The aggregations of the oil and surfactant molecules are observed throughout the simulation. After 8 ns of simulation, the molecules start to aggregate to form one spherical micelle where the POEs molecules are surrounded by the non-ionic surfactant (Span20) molecules with an average size of 4.2 ± 0.05 nm. The size of the micelle and the ability of palm-based nano-emulsion to self-assemble suggest that this nano-emulsion can potentially use in transdermal drug delivery system.

Abdul Rahman, Mohd. Basyaruddin; Huan, Qiu-Yi; Tejo, Bimo A.; Basri, Mahiran; Salleh, Abu Bakar; Rahman, Raja Noor Zaliha Abdul

2009-10-01

252

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

Microsoft Academic Search

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

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

2004-01-01

253

Surfactant phospholipid metabolism  

PubMed Central

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

Agassandian, Marianna; Mallampalli, Rama K.

2012-01-01

254

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

E-print Network

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

Huang, Jianbin

255

Solution properties and electrospinning of phosphonium gemini surfactants.  

PubMed

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

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

2014-06-14

256

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

Microsoft Academic Search

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

Milton J. Rosen; Li D. Song

1996-01-01

257

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

NASA Astrophysics Data System (ADS)

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

Javadian, Soheila; Yousefi, Ali; Neshati, Jaber

2013-11-01

258

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

PubMed

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

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

2013-06-15

259

Nanoindentation of surfactant aggregates  

Microsoft Academic Search

Surfactants are important for a wide range of applications dealing with one-dimensional nanoscale materials, including dispersion of carbon nanotubes, as organic templates in mesoporous silica thin films, and for the fabrication of silica nanowires. There is therefore great interest in better understanding the structure and properties of surfactant aggregates at the solid–liquid interface. Here, classical molecular dynamics simulations with empirical

Patrick Y. Chiu; Kunal Shah; Susan B. Sinnott

2010-01-01

260

ADSORPTION OF SURFACTANTS  

EPA Science Inventory

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

261

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

Microsoft Academic Search

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

Tohren C. G. Kibbey; Lixia Chen

2008-01-01

262

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

PubMed

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

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

2014-06-11

263

Measurement of emulsion flow in porous media: Improvements in heavy oil recovery  

NASA Astrophysics Data System (ADS)

Many heavy oil and bitumen reservoirs in the world are too small or thin for thermal enhanced oil recovery methods to be economic. In these fields, novel methods of less energy intensive, non-thermal technologies are required. Previous experience has shown that the injection of low concentrations of aqueous alkali-surfactant solutions into the reservoir can significantly improve the oil recovery, beyond that of waterflooding. This is due to the in-situ formation of emulsions, which plug off the water channels and lead to improved sweep efficiency in the reservoir. The proper control of these floods requires methods for monitoring the formation and effect of these emulsions. In this paper, the results of laboratory core floods are interpreted to demonstrate how the pressure and flow response can be related to the formation of these emulsions. A new technique (low field NMR) is also used to directly measure W/O emulsions in porous media. Finally, a numerical study is performed in order to demonstrate how the in-situ formation of emulsions can be simply represented in simulation software.

Bryan, J.; Wang, J.; Kantzas, A.

2009-02-01

264

Solubilization of polycyclic aromatic hydrocarbons in micellar nonionic surfactant solutions  

SciTech Connect

Experimental data are presented on the enhanced apparent solubilities of naphthalene, phenanthrene, and pyrene resulting from solubilization in aqueous solutions of four commercial, nonionic surfactants: an alkyl polyoxyethylene (POE) type, two octylphenol POE types, and a nonylphenol POE type. Apparent solubilities of the polycyclic aromatic hydrocarbon (PAH) compounds in surfactant solutions were determined by radiolabeled techniques. Solubilization of each PAH compound commenced at the surfactant critical micelle concentration and was proportional to the concentration of surfactant in micelle form. The partitioning of organic compounds between surfactant micelles and aqueous solution is characterized by a mole fraction micelle-phase/aqueous-phase partition coefficient, K{sub m}. Values of log K{sub m} for PAH compounds in surfactant solutions of this study range from 4.57 to 6.53. Log K{sub m} appears to be a linear function of log K{sub ow} for a given surfactant solution. A knowledge of partitioning in aqueous surfactant systems is a prerequisite to understanding mechanisms affecting the behavior of hydrophobic organic compounds in soil-water systems in which surfactants play a role in contaminant remediation or facilitated transport.

Edwards, D.A.; Luthy, R.G.; Liu, Zhongbao (Carnegie Mellon Univ., Pittsburgh, PA (USA))

1991-01-01

265

Surfactant dependent morphology of polymeric capsules of perfluorooctyl bromide: Influence of polymer adsorption at the dichloromethane–water interface  

Microsoft Academic Search

In a strategy to develop more stable ultrasound contrast agents (UCAs), we have designed a process to obtain nano\\/microcapsules with a single core of liquid perfluorocarbon within a biodegradable polymeric shell of homogeneous thickness. During the optimization of perfluorooctyl bromide (PFOB) encapsulation by solvent emulsion-evaporation, a marked influence of surfactants has been observed. While sodium cholate leads to spherical capsules

Emilia Pisani; Elias Fattal; Juliane Paris; Catherine Ringard; Véronique Rosilio; Nicolas Tsapis

2008-01-01

266

Mixtures of cationic copolymers and oppositely charged surfactants: effect of polymer charge density and ionic strength on the adsorption behavior at the silica-aqueous interface.  

PubMed

This study addresses polymer-surfactant interactions at solid-liquid interfaces and how these can be manipulated by modulating the association between ionic surfactant and oppositely charged polymer, with a particular focus on electrostatic interactions. For this purpose, the interaction of a series of cationic copolymers of vinylpyrrolidone and quaternized vinylimidazol with sodium dodecyl sulfate (SDS) at the silica-aqueous interface was followed by in situ ellipsometry. To reveal the nature of the interaction, we performed measurements for different copolyion charge densities, in the absence and presence of added salt. The path-dependence of the interaction was studied by comparing the adsorption under two different conditions, adsorption from premixed solutions and sequential addition of surfactant to the polymer solution, but the same end state. The reversibility of the adsorption process was studied by following the effect of dilution on the adsorbed layer. All copolyions adsorbed to both silica and hydrophobized silica, revealing the importance of both hydrophobic and electrostatic attractive interactions. On both types of surface, an increase in adsorbed amount was found on lowering the fraction of charged units. An increased ionic strength gave an increased adsorbed amount in all cases, but especially on hydrophobic surfaces. The adsorbed amount on silica from mixtures of the copolyions with SDS peaked at an SDS concentration corresponding closely to the concentration of cationic charges of the different polyions. Around the region of charge equivalence, there was also a phase separation in the bulk. At higher concentrations of SDS, a redissolution in the bulk, and a decrease in adsorbed amount, occurred as a result of excess SDS binding to the complexes. For the most highly charged polyions, we observed a decrease in adsorbed amount, and a shift in the adsorption maxima to lower SDS concentrations, with increasing ionic strength. PMID:22301772

Mohr, Andreas; Nylander, Tommy; Piculell, Lennart; Lindman, Björn; Boyko, Volodymyr; Bartels, Frank Wilko; Liu, Yaqian; Kurkal-Siebert, Vandana

2012-03-01

267

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

PubMed

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

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

2014-10-01

268

Measuring GBAR with emulsion detector  

NASA Astrophysics Data System (ADS)

The motivation of the AEgIS experiment is to test the universality of free fall with antimatter. The goal is to reach a relative uncertainty of 1% for the measurement of the earth's gravitational acceleration \\bar {g} on an antihydrogen beam. High vertex position resolution is required for a position detector. An emulsion based detector can measure the annihilation vertex of antihydrogen atoms with a resolution of 1-2 ?m, which if realized in the actual experiment will enable a 1% measurement of \\bar {g} with less than 1000 \\bar {H} atoms. Developments and achievements on emulsion detectors for the AEgIS experiment are presented here.

Ariga, T.; Aghion, S.; Ahlén, O.; Amsler, C.; Ariga, A.; Belov, A. S.; Berggren, K.; Bonomi, G.; Bräunig, P.; Bremer, J.; Brusa, R. S.; Cabaret, L.; Canali, C.; Caravita, R.; Castelli, F.; Cerchiari, G.; Cialdi, S.; Comparat, D.; Consolati, G.; Derking, H.; di Domizio, S.; di Noto, L.; Doser, M.; Dudarev, A.; Ereditato, A.; Ferragut, R.; Fontana, A.; Genova, P.; Giammarchi, M.; Gligorova, A.; Gninenko, S. N.; Haider, S.; Huse, T.; Jordan, E.; Jørgensen, L. V.; Kaltenbacher, T.; Kawada, J.; Kellerbauer, A.; Kimura, M.; Knecht, A.; Krasniký, D.; Lagomarsino, V.; Lehner, S.; Magnani, A.; Malbrunot, C.; Mariazzi, S.; Matveev, V. A.; Nebbia, G.; Nédélec, P.; Oberthaler, M. K.; Pacifico, N.; Petrá?ek, V.; Pistillo, C.; Prelz, F.; Prevedelli, M.; Regenfus, C.; Riccardi, C.; Røhne, O.; Rotondi, A.; Sandaker, H.; Scampoli, P.; Storet, J.; Subieta Vasquez, M. A.; Špa?ek, M.; Testera, G.; Widmann, E.; Yzombard, P.; Zavaterelli, S.; Zmeskal, J.

2014-05-01

269

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

270

Emulsion Droplet Combustion in Microgravity: Water/Heptane Emulsions  

NASA Technical Reports Server (NTRS)

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

Avedisian, C. Thomas

1997-01-01

271

Waterflooding employing amphoteric surfactants  

SciTech Connect

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

Stournas, S.

1980-08-05

272

Patterning nanoparticles into rings by "2-D Pickering emulsions".  

PubMed

We present a simple method for the two-dimensional self-assembly of CdSe/ZnS quantum dots (QDs) into well-defined rings at the air/water interface, through the formation of "2-D Pickering emulsions". Surfactant molecules assemble at the air/water interface into islands that are subsequently surrounded by adsorption of QDs from the aqueous subphase. The QD rings emanating from this process range from ?100 nm to several micrometers in diameter, as characterized by atomic force microscopy, scanning eectron microscopy, and fluorescence microscopy. The deposition and alignment of QD rings onto large areas (cm(2)) were demonstrated by dip-coating onto a substrate. This simple method produces rings of QDs without the need for any templating or fabrication steps. PMID:24645916

Lee, Cheol Hee; Crosby, Alfred J; Hayward, Ryan C; Emrick, Todd

2014-04-01

273

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

PubMed

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

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

2005-08-25

274

Hollandaise Sauce: Emulsion at Work  

NSDL National Science Digital Library

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

Exploratorium

2012-10-03

275

Emulsion Chamber Technology Experiment (ECT)  

NASA Technical Reports Server (NTRS)

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

Gregory, John C.; Takahashi, Yoshiyuki

1996-01-01

276

Extraction of lanthanoids by liquid surfactant membranes  

SciTech Connect

Separation and concentration of lanthanoids such as La/sup 3 +/, Nd/sup 3 +/, Sm/sup 3 +/, Eu/sup 3 +/, Gd/sup 3 +/, Dy/sup 3 +/, and Yb/sup 3 +/ were carried out using liquid surfactant membranes containing 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester as a carrier. Under the condition of sufficiently high distribution ratio, more than 98% of these metal ions was extracted within 5 min even if the volume ratio of W/O emulsion to the external aqueous phase was as low as 1/32. The ratio of the concentration of metal ions in the internal aqueous phase to that in the external feed phase reached about 50,000 within 20 min. In the conventional solvent extraction of Yb/sup 3 +/, the aggregates of metal-carrier complexes, which were insoluble in the organic membrane phase, were formed at high loading ratio. In the extraction of Yb/sup 3 +/ by liquid surfactant membranes, however, formation of such aggregates was suppressed because both extraction and stripping occurred simultaneously on both sides of the membranes. The rate of interfacial reaction between lanthanoids and the carrier was remarkably reduced by the presence of the emulsifier, and the forward reaction rate was represented by r/sub f/ = k/sub f/(Ln/sup 3 +/)((HR)/sub 2/)/sup 3//(H/sup +/)/sup 3/ where ((HR)/sub 2/) is the concentration of the dimer of the carrier. The rate of the extraction by liquid surfactant membranes was satisfactorily simulated by a proposed permeation model, i.e., a multilayer shell model.

Teramoto, M.; Sakuramoto, T.; Koyama, T.; Matsuyama, H.; Miyake, Y.

1986-05-01

277

The emulsion chamber technology experiment  

NASA Technical Reports Server (NTRS)

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

Gregory, John C.

1992-01-01

278

Transdermal Delivery of an Anti-Cancer Drug via W\\/O Emulsions Based on Alkyl Polyglycosides and Lecithin: Design, Characterization, and In Vivo Evaluation of the Possible Irritation Potential in Rats  

Microsoft Academic Search

The purpose of this work was to develop w\\/o emulsions that could be safely used to promote transdermal delivery of 5-fluorouracil\\u000a (5-FU). Two pseudo-ternary phase diagrams comprising oleoyl-macrogol glycerides, water, and a surfactant\\/co-surfactant (S\\/CoS)\\u000a mixture of lecithin, ethanol, and either coco glucoside or decyl glucoside were investigated for their potential to develop\\u000a promising 5-FU emulsions. Six systems were selected and

Aliaa Nabil ElMeshad; Mina Ibrahim Tadros

2011-01-01

279

Platinum nanoparticles from size adjusted functional colloidal particles generated by a seeded emulsion polymerization process  

PubMed Central

Summary The benefits of miniemulsion and emulsion polymerization are combined in a seeded emulsion polymerization process with functional seed particles synthesized by miniemulsion polymerization. A systematic study on the influence of different reaction parameters on the reaction pathway is conducted, including variations of the amount of monomer fed, the ratio of initiator to monomer and the choice of surfactant and composition of the continuous phase. Critical parameters affecting the control of the reaction are determined. If carefully controlled, the seeded emulsion polymerization with functional seed particles yields monodisperse particles with adjustable size and functionalities. Size-adjusted platinum-acetylacetonate containing latex particles with identical seed particles and varied shell thicknesses are used to produce arrays of highly ordered platinum nanoparticles with different interparticle distances but identical particle sizes. For that, a self-assembled monolayer of functional colloids is prepared on a solid substrate and subsequently treated by oxygen plasma processing in order to remove the organic constituents. This step, however, leads to a saturated state of a residual mix of materials. In order to determine parameters influencing this saturation state, the type of surfactant, the amount of precursor loading and the size of the colloids are varied. By short annealing at high temperatures platinum nanoparticles are generated from the saturated state particles. Typically, the present fabrication method delivers a maximum interparticle distance of about 260 nm for well-defined crystalline platinum nanoparticles limited by deformation processes due to softening of the organic material during the plasma applications. PMID:22003452

Vogel, Nicolas; Ziener, Ulrich; Manzke, Achim; Plettl, Alfred; Ziemann, Paul; Biskupek, Johannes; Weiss, Clemens K

2011-01-01

280

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

PubMed

Emulsions are widely used for pharmaceutical, food, and cosmetic applications. To guarantee that their critical quality attributes meet specifications, it is desirable to monitor the emulsion manufacturing process. However, finding of a suitable process analyzer has so far remained challenging. This article introduces diffusing wave spectroscopy (DWS) as an at-line technique to follow the manufacturing process of a model oil-in-water pharmaceutical emulsion containing xanthan gum. The DWS results were complemented with mechanical rheology, microscopy analysis, and stability tests. DWS is an advanced light scattering technique that assesses the microrheology and in general provides information on the dynamics and statics of dispersions. The obtained microrheology results showed good agreement with those obtained with bulk rheology. Although no notable changes in the rheological behavior of the model emulsions were observed during homogenization, the intensity correlation function provided qualitative information on the evolution of the emulsion dynamics. These data together with static measurements of the transport mean free path (l*) correlated very well with the changes in droplet size distribution occurring during the emulsion homogenization. This study shows that DWS is a promising process analytical technology tool for development and manufacturing of pharmaceutical emulsions. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:3902-3913, 2014. PMID:25302803

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

2014-12-01

281

Amphoteric water-in-oil self-inverting polymer emulsion  

SciTech Connect

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

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

1985-03-19

282

ADSORPTION OF ETHOXYLATED NONIONIC SURFACTANTS FROM SILOXANE-BASED SOLVENT AND AQUEOUS SYSTEMS: USE OF QCM AND MODEL POLYMERIC SURFACES  

Microsoft Academic Search

Adsorption behavior was quantified with pure ethoxylated nonionic surfactants onto different polymeric surfaces (hydrophilic cotton and hydrophobic polyester) and model hydrophilic gold surface. The polymer materials used for the study were characterized using SEM. The role of ethylene oxide group variation in surfactant-polymer interaction was established using pure surfactant with the same alkyl chain length but varying ethoxylate chain lengths.

Abhay R. Ladhe; D. Bhattacharyya

2009-01-01

283

Capillary mechanisms in membrane emulsification: oil-in-water emulsions stabilized by Tween 20 and milk proteins  

Microsoft Academic Search

We investigate the process of membrane emulsification in the presence of the nonionic surfactant Tween 20, and the milk proteins Na-caseinate and beta-lactoglobulin (BLG). Our goal is to examine the factors which control the drop-size distribution in the formed emulsions. The drops are produced at the outer surface of a cylindrical microporous glass membrane, so that the process of their

N. C. Christov; D. N. Ganchev; N. D. Vassileva; N. D. Denkov; K. D. Danov; P. A. Kralchevsky

2002-01-01

284

Enhanced Oil Recovery of Viscous Oil by Injection of Water-in-Oil Emulsion Made with Used Engine Oil  

E-print Network

with the organic acids within heavy oil and form in situ surfactants, thus lowering the interfacial tension (IFT) and forming emulsions (Selby et al., 1989). Johnson (Johnson Jr., 1976) proposed four different mechanisms by which caustic flooding may improve oil... flooding the minimum IFT is often achieved at very low concentrations of alkali. However, higher concentrations of alkali are often injected due to large consumption by the rock (Drillet and Defives, 1991; Mohnot et al., 1987; Novosad and Novosad, 1984...

Fu, Xuebing

2012-08-20

285

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

PubMed

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

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

2013-07-15

286

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

PubMed

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

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

2014-05-15

287

Steroidal compounds in commercial parenteral lipid emulsions.  

PubMed

Parenteral nutrition lipid emulsions made from various plant oils contain steroidal compounds, called phytosterols. During parenteral administration of lipid emulsions, phytosterols can reach levels in the blood that are many fold higher than during enteral administration. The elevated phytosterol levels have been associated with the development of liver dysfunction and the rare development of liver failure. There is limited information available in the literature related to phytosterol concentrations in lipid emulsions. The objective of the current study was to validate an assay for steroidal compounds found in lipid emulsions and to compare their concentrations in the most commonly used parenteral nutrition lipid emulsions: Liposyn(®) II, Liposyn(®) III, Lipofundin(®) MCT, Lipofundin(®) N, Structolipid(®), Intralipid(®), Ivelip(®) and ClinOleic(®). Our data demonstrates that concentrations of the various steroidal compounds varied greatly between the eight lipid emulsions, with the olive oil-based lipid emulsion containing the lowest levels of phytosterols and cholesterol, and the highest concentration of squalene. The clinical impression of greater incidences of liver dysfunction with soybean versus MCT/LCT and olive/soy lipid emulsions may be reflective of the levels of phytosterols in these emulsions. This information may help guide future studies and clinical care of patients with lipid emulsion-associated liver dysfunction. PMID:23016123

Xu, Zhidong; Harvey, Kevin A; Pavlina, Thomas; Dutot, Guy; Hise, Mary; Zaloga, Gary P; Siddiqui, Rafat A

2012-08-01

288

Voltammetric behavior of cefdinir in solubilized system  

Microsoft Academic Search

The voltammetric behavior of cefdinir has been studied in different surfactant media viz. anionic, neutral, and cationic surfactants over the pH range 2.5–12 in phosphate buffer (0.2 M). Addition of cationic surfactant (citrimide) to the cefdinir containing electrolyte enhanced the reduction current signal while anionic surfactant (sodium lauryl) and neutral surfactant (Tween-20) showed an opposite effect. The reduction process was

Rajeev Jain; Ashish Dwivedi; Ritesh Mishra

2008-01-01

289

Preparation and characterization of surfactant-modified hydroxyapatite/zeolite composite and its adsorption behavior toward humic acid and copper(II).  

PubMed

A novel composite material, i.e., surfactant-modified hydroxyapatite/zeolite composite, was used as an adsorbent to remove humic acid (HA) and copper(II) from aqueous solution. Hydroxyapatite/zeolite composite (HZC) and surfactant-modified HZC (SMHZC) were prepared and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscope. The adsorption of HA and copper(II) on SMHZC was investigated. For comparison purposes, HA adsorption onto HZC was also investigated. SMHZC exhibited much higher HA adsorption capacity than HZC. The HA adsorption capacity for SMHZC decreased slightly with increasing pH from 3 to 8 but decreased significantly with increasing pH from 8 to 12. The copper(II) adsorption capacity for SMHZC increased with increasing pH from 3 to 6.5. The adsorption kinetic data of HA and copper(II) on SMHZC obeyed a pseudo-second-order kinetic model. The adsorption of HA and copper(II) on SMHZC took place in three different stages: fast external surface adsorption, gradual adsorption controlled by both film and intra-particle diffusions, and final equilibrium stage. The equilibrium adsorption data of HA on SMHZC better fitted to the Langmuir isotherm model than the Freundlich isotherm model. The equilibrium adsorption data of copper(II) on SMHZC could be described by the Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models. The presence of copper(II) in solution enhanced HA adsorption onto SMHZC. The presence of HA in solution enhanced copper(II) adsorption onto SMHZC. The mechanisms for the adsorption of HA on SMHZC at pH 7 may include electrostatic attraction, organic partitioning, hydrogen bonding, and Lewis acid-base interaction. The mechanisms for the adsorption of copper(II) on SMHZC at pH 6 may include surface complexation, ion exchange, and dissolution-precipitation. The obtained results indicate that SMHZC can be used as an effective adsorbent to simultaneously remove HA and copper(II) from water. PMID:22961484

Zhan, Yanhui; Lin, Jianwei; Li, Jia

2013-04-01

290

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

PubMed

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

Yoshimura, Tomokazu; Sakato, Ayako; Esumi, Kunio

2013-01-01

291

Electrochromism in switchable nematic emulsions  

NASA Astrophysics Data System (ADS)

Switchable nematic emulsions are composite systems formed by liquid-crystal droplets dispersed in a fluid, homogeneous, monomer matrix, which can be turned from an opaque to an optically transparent state by application of a suitable ac electric field. An electrochromic device provides a reversible and visible change in its transmittance and/or reflectance as the result of either oxidation or reduction electrochemical processes. Both devices have been proven to be useful for a variety of electro-optical applications as switchable windows, electromagnetic shutters, and displays. This letter reports preliminary results on a bifunctional device based on a switchable nematic emulsion, which hosts electrochemical reactions. The presence of a liquid-crystal dispersion ensures the switching from a scattering and opaque state to a transmissive and transparent state, while the oxidation-reduction reactions allow a contemporary and independent change in color.

Nicoletta, F. P.; Cupelli, D.; De Filpo, G.; Chidichimo, G.

2004-05-01

292

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

PubMed

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

Atanase, Leonard Ionut; Riess, Gérard

2013-05-20

293

Effects of surfactants on the kinetics of acetamiprid photolysis  

Microsoft Academic Search

Photolysis behavior of acetamiprid in different kinds of surfactant solutions were investigated. The results showed that acetamiprid\\u000a was prone to photolysis when exposed to the irradiation of a mercury lamp, and the photolysis kinetics fit in well with the\\u000a first-order kinetic equation. Surfactants did not participate in the acetamiprid’s photolysis process directly, whereas they\\u000a all had obvious inhibiting effects on

Xie Guohong; L. V. Jianxiao; Liu Guoguang; Sun Dezhi; Zheng Liqing

2008-01-01

294

Synthesis of organic rectorite with novel Gemini surfactants for copper removal  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

295

Nanoindentation of surfactant aggregates.  

PubMed

Surfactants are important for a wide range of applications dealing with one-dimensional nanoscale materials, including dispersion of carbon nanotubes, as organic templates in mesoporous silica thin films, and for the fabrication of silica nanowires. There is therefore great interest in better understanding the structure and properties of surfactant aggregates at the solid-liquid interface. Here, classical molecular dynamics simulations with empirical potentials are used to compare the structures and mechanical properties of cationic surfactant micelles that are being indented with carbon nanotubes and silica nanowires at the silica-water interface. The findings are compared to the results of bulk indentation with graphite and silica surfaces, and the influence of nanometer-scale curvature on the results is described. PMID:20554291

Chiu, Patrick Y; Shah, Kunal; Sinnott, Susan B

2010-09-01

296

Thermally stable emulsion explosive composition  

SciTech Connect

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

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

1982-03-30

297

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

PubMed

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

ElMeshad, Aliaa Nabil; Tadros, Mina Ibrahim

2011-03-01

298

Shear and dilational interfacial rheology of surfactant-stabilized droplets.  

PubMed

A new measurement method is suggested that is capable of probing the shear and dilational interfacial rheological responses of small droplets, those of size comparable to real emulsion applications. Freely suspended aqueous droplets containing surfactant and non-surface-active tracer particles are transported through a rectangular microchannel by the plane Poiseuille flow of the continuous oil phase. Optical microscopy and high-speed imaging record the shape and internal circulation dynamics of the droplets. Measured circulation velocities are coupled with theoretical descriptions of the droplet dynamics in order to determine the viscous (Boussinesq) and elastic (Marangoni) interfacial effects. A new Marangoni-induced stagnation point is identified theoretically and observed experimentally. Particle velocimetry at only two points (including gradients) in the droplet is sufficient to determine the amplitudes of the dilational and shear responses. We investigate the sensitivity for measuring interfacial properties and compare results from droplets stabilized by a small-molecule surfactant (butanol) and those stabilized by relatively large block copolymer molecules. Future increased availability of shear and dilational interfacial rheological properties is anticipated to lead to improved rules of thumb for emulsion preparation, stabilization, and general practice. PMID:22520210

Erk, Kendra A; Martin, Jeffrey D; Schwalbe, Jonathan T; Phelan, Frederick R; Hudson, Steven D

2012-07-01

299

Microencapsulation of rosmarinic acid using polycaprolactone and various surfactants.  

PubMed

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

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

2010-06-01

300

Facile fabrication of Pickering emulsion polymerized polystyrene/laponite composite nanoparticles and their electrorheology.  

PubMed

Polystyrene (PS)/laponite composite nanoparticles were fabricated using a surfactant-free Pickering emulsion polymerization method, in which emulsions of styrene dispersed in water were stabilized by hydrophilic laponite modified with cetyltrimethylammonium bromide. The PS/laponite nanoparticles, of which their surface was covered compactly by laponite clay platelets, were observed by scanning electron microscopy. Fourier-transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis confirmed their chemical composition, crystallographic structure, and thermal properties and weight loss percentage of the laponite located on the surface of the PS particle, respectively. When an external electrical field was applied, the chain-like structure of the laponite coated nano-sized PS particle exhibiting electrorheological characteristics was observed by optical microscopy. The electrorheological performance of the bulk properties was also examined using a rotational rheometer equipped with a high voltage generator. PMID:23332941

Kim, Young Jae; Liu, Ying Dan; Choi, Hyoung Jin; Park, Soo-Jin

2013-03-15

301

Emulsion liquid membrane extraction of lactic acid from aqueous solutions and fermentation broth.  

PubMed

Studies on the batch extraction of lactic acid using an emulsion liquid membrane system are reported. The membrane phase consists of the tertiary amine carrier Alamine 336 and the surfactant Span 80 dissolved in n-heptane/paraffin and aqueous solutions of sodium carbonate in the internal phase. The effects of internal phase reagent, extraction temperature, and initial external phase pH on the extraction efficiency and the emulsion swelling are examined. A statistical factorial experiment on extraction from clarified lactic acid fermentation broth was carried out to obtain knowledge of the performance of the extraction system from a broth. The extraction efficiency from the fermentation broth is found to be lower as compared to aqueous solutions of pure lactic acid. The effect of pH and the presence of other ionic species on selectivity are discussed. PMID:18609647

Schöller, C; Chaudhuri, J B; Pyle, D L

1993-06-01

302

In situ functionalization and PEO coating of iron oxide nanocrystals using seeded emulsion polymerization.  

PubMed

Herein we demonstrate that seeded emulsion polymerization is a powerful tool to produce multiply functionalized PEO coated iron oxide nanocrystals. Advantageously, by simple addition of functional surfactants, functional monomers, or functional polymerizable linkers-solely or in combinations thereof-during the seeded emulsion polymerization process, a broad range of in situ functionalized polymer-coated iron oxide nanocrystals were obtained. This was demonstrated by purposeful modulation of the zeta potential of encapsulated iron oxide nanocrystals and conjugation of a dyestuff. Successful functionalization was unequivocally proven by TXRF. Furthermore, the spatial position of the functional groups can be controlled by choosing the appropriate spacers. In conclusion, this methodology is highly amenable for combinatorial strategies and will spur rapid expedited synthesis and purposeful optimization of a broad scope of nanocrystals. PMID:23530830

Kloust, Hauke; Schmidtke, Christian; Feld, Artur; Schotten, Theo; Eggers, Robin; Fittschen, Ursula E A; Schulz, Florian; Pöselt, Elmar; Ostermann, Johannes; Bastús, Neus G; Weller, Horst

2013-04-16

303

Aggregate transitions in mixtures of anionic sulfonate gemini surfactant with cationic ammonium single-chain surfactant.  

PubMed

Aggregation behaviors in mixtures of an anionic gemini surfactant 1,3-bis(N-dodecyl-N-propanesulfonate sodium)-propane (C(12)C(3)C(12)(SO(3))(2)) and a cationic single-chain surfactant cetyltrimethylammonium bromide (CTAB) have been investigated in aqueous solutions at pH 9.5 by turbidity, rheology, isothermal titration microcalorimetry (ITC), cryogenic transmission electron microscopy, and dynamic light scattering. Reversible aggregate transitions from spherical micelles to wormlike micelles, vesicles, and back to wormlike micelles and spherical micelles are successfully realized through fine regulation over the mixing ratio of surfactants, i.e., the anionic/cationic charge ratio. The five aggregate regions display distinguished phase boundaries so that the aggregate regions can be well controlled. From thermodynamic aspect, the ITC curves clearly reflect all the aggregate transitions and the related interaction mechanism. The self-assembling ability of the C(12)C(3)C(12)(SO(3))(2)/CTAB mixtures are significantly improved compared with both individual surfactants. Micelle growth from spherical to long wormlike micelles takes place at a relative low total concentration, i.e., 2.0 mM. The wormlike micelle solution at 10 mM or higher shows high viscosity and shear thinning property. Moreover, the C(12)C(3)C(12)(SO(3))(2)/CTAB mixtures do not precipitate even at 1:1 charge ratio and relative high concentration. It suggests that applying gemini surfactant should be an effective approach to improve the solubility of anionic/cationic surfactant mixtures and in turn may promote applications of the surfactant mixtures. PMID:23205820

Tian, Maozhang; Zhu, Linyi; Yu, Defeng; Wang, Yingxiong; Sun, Shufeng; Wang, Yilin

2013-01-10

304

Deactivation efficiency of stabilized bactericidal emulsions.  

PubMed

Biocide emulsions stabilized with various stabilizing agents were prepared and characterized, and their efficiency in bacteria deactivation was evaluated. A number of stabilizing agents were tested for their stabilizing effect on emulsions of thiocyanomethylthiobenzothiazole (TCMTB) biocide. Two agents, the most successful in stabilizing the biocide, were chosen for further studies: high molecular weight polyethyleneimine (PEI) and an amphiphilic block copolymer of poly(caprolactone)-b-poly(acrylic acid) (PCL(33)-b-PAA(33)). The emulsion droplet sizes varied between 325 and 500 nm. Deactivation of bacteria was studied by exposing E. coli ATCC 11229 bacteria dispersions to emulsions stabilized by positively charged PEI or negatively charged PCL-b-PAA micelles and by measuring their absorbance; E. coli do not grow with time in the presence of biocide emulsions. PEI molecules alone act as biocide and deactivate the bacteria. PCL-b-PAA micelles as stabilizing agent do not affect the growth of the E. coli ; bacteria are deactivated by TCMTB released from the emulsion droplets. The kinetics of emulsion dissolution studies revealed for both stabilizing agents a decrease in droplet size with time while the emulsions were subjected to dialysis. The biocide was released from the emulsions within ?250 min; the droplet shells consist mostly of PEI or PCL-b-PAA insoluble complexes with the biocide, which do not dissolve during dialysis. SEM images confirm the presence of residual crumbled shells with holes after 24 h of dialysis. PMID:21823610

Vyhnalkova, Renata; Eisenberg, Adi; van de Ven, Theo G M

2011-09-20

305

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

Microsoft Academic Search

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

Tanushree Chakraborty; Soumen Ghosh

2007-01-01

306

Genetic disorders of surfactant proteins.  

PubMed

Inherited disorders of pulmonary surfactant-associated proteins are rare but provide important insights into unique mechanisms of surfactant dysfunction. Recessive loss-of-function mutations in the surfactant protein-B and the ATP-binding cassette family member A3 (ABCA3) genes present as lethal surfactant deficiency in the newborn, whereas other recessive mutations in ABCA3 and dominant mutations in the surfactant protein-C gene result in interstitial lung disease in older infants and children. The molecular basis and the genetic and tissue-based approaches to the evaluation of children suspected of having one of these disorders are discussed. PMID:17575475

Hamvas, Aaron; Cole, F Sessions; Nogee, Lawrence M

2007-01-01

307

Self-assembly of gemini surfactants: a computer simulation study.  

PubMed

The self-assembly behavior of gemini (dimeric or twin-tail) dicarboxylate disodium surfactants is studied using molecular dynamics simulations. A united atom model is employed for the surfactants with fully atomistic counterions and water. This gemini architecture, in which two single tailed surfactants are joined through a flexible hydrophobic linker, has been shown to exhibit concentration-dependent aqueous self-assembly into lyotropic phases including hexagonal, gyroid, and lamellar morphologies. Our simulations reproduce the experimentally observed phases at similar amphiphile concentrations in water, including the unusual ability of these surfactants to form gyroid phases over unprecedentedly large amphiphile concentration windows. We demonstrate quantitative agreement between the predicted and experimentally observed domain spacings of these nanostructured materials. Through careful conformation analyses of the surfactant molecules, we show that the gyroid phase is electrostatically stabilized related to the lamellar phase. By starting with a lamellar phase, we show that use of a bulkier N(CH(3))(4)(+) counterion in place of Na(+) drives the formation of a gyroid phase. Decreasing the charge on the surfactant headgroups by carboxylate protonation decreases the degree of order in the lamellar phase. Using our models, we show that the translational diffusion of water and the Na(+) counterions is decreased by several orders of magnitude over the studied concentration range, and we attribute these effects to strong correlations between the mobile species and the surfactant headgroups. PMID:22967267

Mondal, Jagannath; Mahanthappa, Mahesh; Yethiraj, Arun

2013-04-25

308

Preferential surfactant utilization by a PAH-degrading strain: effects on micellar solubilization phenomena.  

PubMed

Biodegradable nonionic Tween series surfactants were employed to assess the effects of synthetic surfactants on the bioavailability of a target polycyclic aromatic hydrocarbon (PAH), phenanthrene, in soil/sediment-free micellar solutions. Dosages of surfactants in excess of their respective critical micelle concentrations (CMCs) dramatically enhanced solubilization of phenanthrene, but the micellar-solubilized phenanthrene was neither directly nor readily bioavailable to the PAH-degrading strain, Sphingomonas paucimobilis EPA 505, used in these bioavailability experiments. The microorganism preferred instead to utilize hydrophobic fractions of the Tween surfactants as a carbon source, resulting in an imbalance of amphiphilic moieties in surfactant molecules and associated destabilization of micelles. This effect was assessed by measurements of surface tension, CMCs, weight-based PAH solubilization ratios, and by characterizations of the surfactants via HPLC separation and emulsification behavior. The observations and analyses lead to a conclusion that preferential biological destabilization of surfactant micelles effects an associated release of phenanthrene to the aqueous phase. The phenanthrene so released then apparently reverts to a crystallized form that appears to be bioavailable only through normal re-dissolution to the aqueous phase. This is, to our knowledge, the first attempt to characterize and quantify changes in the properties and solubilization behaviors of surfactant micelles resulting from their partial and preferential biodegradation. The associated re-deposition of previously micellar-solubilized PAHs observed and the loss of solubilization capacity of recovered surfactants have significant implications for applications of surfactant-enhanced bioremediation of contaminated soils and sediments. PMID:12953868

Kim, Han S; Weber, Walter J

2003-08-15

309

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

PubMed

Nanocomposite polyHIPE foams with open-cellular morphology were obtained using nanoparticles (?Fe2O3/Fe3O4), surfactant (Pluronic L121) or nanoparticle/surfactant stabilized dicyclopentadiene high internal phase emulsions (DCPD HIPEs). Upon curing, cavity sizes were found to vary drastically between 950 ± 360 µm down to 7 ±3 µm depending on the HIPE formulations. As-obtained nanocomposite polyHIPE foams were functionalized using elemental bromine in THF. Upon bromination the nanoparticles are moved from the cavities surfaces into the bulk phase of the polymer scaffold, which affects the inductive-heating capability of the magnetic nanocomposite foams decreasing it by the factor of 2. PMID:24664347

Kova?i?, Sebastijan; Matsko, Nadejda B; Ferk, Gregor; Slugovc, Christian

2014-01-01

310

Preparation of aqueous dispersion of thermoplastic sizing agent for carbon fiber by emulsion/solvent evaporation  

NASA Astrophysics Data System (ADS)

In this work, different sizing agent aqueous dispersions based on polyetherimide (PEI) were elaborated in order to improve the interface between carbon fibers and a thermoplastic matrix (PEEK). The dispersions were obtained by the emulsion/solvent evaporation technique. To optimize the stability and the film formation on the fibers, two surfactants were tested at different concentrations, with different concentrations of PEI. The dispersions obtained were characterized by dynamic light scattering (DLS) and the stability evaluated by analytical centrifugation (LUMiFuge). The selected dispersions were tested for film formation ability by scanning electron microscopy (SEM), and the sizing performance was assessed by observation of the fiber/matrix interface by SEM. The results revealed that an aqueous dispersion of PEI, stabilized by sodium dodecyl sulfate as the surfactant, led to very stable sizing agent aqueous dispersion with ideal film formation and better interface adhesion.

Giraud, Isabelle; Franceschi-Messant, Sophie; Perez, Emile; Lacabanne, Colette; Dantras, Eric

2013-02-01

311

Removal of sparingly soluble organic chemicals from aqueous solutions with surfactant-coated ferrihydrite  

Microsoft Academic Search

A surfactant, sodium dodecyl sulfate (SDS), was adsorbed onto ferrihydrite at low pH and desorbed at high pH. Adsorption isotherms of SDS on ferrihydrite yielded an S-shaped curve typical for surfactant adsorption on mineral surfaces. This behavior is due to the surfactant forming aggregate structures on the solid surface. SDS adsorption and desorption experiments revealed that both processes were fast,

Thomas M. Holsen; Elaine Ruth Taylor; Yong-Chan Seo; Paul R. Anderson

1991-01-01

312

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

Microsoft Academic Search

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

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

2001-01-01

313

Interfacial and colloidal behavior of asphaltenes obtained from Brazilian crude oils  

E-print Network

in the stabilization of water/oil emulsions as well as water/toluene emulsions, with larger effects for C7I in water. A knowl- edge of surface and colloidal properties and behavior of asphaltenes and resins is indispensable

Loh, Watson

314

Microwave emulsion treater with internal coalescer  

Microsoft Academic Search

This patent describes an improvement in a microwave-based emulsion treating system comprising a microwave energy source and a microwave energy applicator having an inlet for an oil and water emulsion to be treated with microwave energy and an outlet for discharge of treated oil and water. The improvement comprising a coalescer medium having a dielectric constant at 2450 MHz of

N. O. Wolf; D. S. Seidner

1989-01-01

315

Quantitative approach to ultrasonic emulsion separation  

Microsoft Academic Search

Ultrasound of 2MHz was irradiated to the emulsion prepared from canola oil and water and flocculation of the oil droplets occurred immediately. By putting the emulsion sample in a thin glass cell and setting it in bath type irradiation equipment, the progress of the separation was quantitatively monitored with the optical absorbance. The use of the cell enables visual observation

Susumu Nii; Shunsuke Kikumoto; Hideaki Tokuyama

2009-01-01

316

Treatment of oil-in-water emulsions  

SciTech Connect

Petroleum is separated from an oil-in-water emulsion containing water-soluble polymer such as polyacrylamide prior to refining by adding amphoteric metal cations (Zn, Al, Sn, and Co) to the emulsion to form a flocculate and then treating the resulting flocculate with a strong base to recover the oil and metal. 11 claims.

Presley, C.T.; Harrison, R.J.

1980-01-08

317

Treatment of oil-in-water emulsions  

SciTech Connect

Petroleum is separated from an ''oil-in-water'' emulsion containing water-soluble polymer prior to refining by adding amphoteric metal cations to the emulsion to form a flocculate and then treating the resulting flocculate with a strong base to recover the oil and metal.

Harrison, R.J.; Presley, C.T.

1980-01-08

318

Emulsions Droplet Capture Mechanism in Porous Media  

NASA Astrophysics Data System (ADS)

This study was undertaken to investigate the physics of emulsion flow in porous media. The objective of experiments were to study the applicability of oil-in-water emulsion as a plugging agent in the vicinity of the well bore for thousands of Canadian gas wells that are continuously leaking gas to surface. The motion of oil droplets and the capture mechanisms were investigated through visualized experiments. Well-characterized emulsions were injected into a micro model resembling a two parallel plate model packed with glass beads. Effects of emulsion properties and wettability of the medium were studied on a plugging mechanism. The results demonstrate the reduction in permeability mainly due to droplets size exclusion compared to the pore constrictions. Also, smaller droplets may lodge and coalesce in pores crevices thereby accelerating the blockage process. Moreover, more viscous emulsions are more effective compared with the less viscous ones due to combined effects of capillary and viscous forces. The deposition of droplets was adjusted through utilizing different preflush solutions. Criteria were set for enhancing emulsion penetration depth thereby defining the extent of the blocked region. In conclusion, this work characterizes the physics of emulsion flow in porous media and demonstrates its application as a novel sealant in near well bore region. The novelty, which constitutes a step-change in technology, is a method that emplaces an emulsion at a desired location in underground media.

Zeidani, Khalil; Polikar, Marcel

2006-03-01

319

Rheology and processing of salad dressing emulsions  

Microsoft Academic Search

In order to study the influence that the processing parameters exert on the rheology and stability of salad dressing emulsions, both steady-state shear and oscillatory measurements, as well as droplet size distribution tests were performed. Emulsions containing a mixture of egg yolk and sucrose stearate as emulsifier were prepared using two different emulsification machines, a rotor-stator turbine and a colloidal

Jose Maria Franco; Antonio Guerrero; Crispulo Gallegos

1995-01-01

320

Effect of surfactant addition on removal of microbubbles using ultrasound.  

PubMed

It is difficult to control the bubble in a liquid by the external operation, because the behavior of the bubble is controlled in buoyancy and flow of liquid. On the other hand, microbubbles, whose diameter is several decades ?m, stably disperse in static liquid because of their small buoyancy and electrical repulsion. When an ultrasound, whose frequency was 2.4 MHz, was irradiated, the milky white microbubbles suspended solution became rapidly clear. In this study, the effects of surfactant addition on the removal of microbubbles from a liquid in an ultrasonic field were investigated. The efficiency of removal of microbubbles decreased with surfactant addition. Surfactant type influenced the size of agglomerated microbubbles, and the efficiency of removal of microbubbles changed. The surface of microbubble was modified by surfactant adsorption, and the steric inhibition influenced the removal of microbubbles. PMID:24745307

Kobayashi, Daisuke; Hayashida, Yoshiyuki; Sano, Kazuki; Terasaka, Koichi

2014-08-01

321

Cocoa particles for food emulsion stabilisation.  

PubMed

Emulsifying properties of cocoa particles have been investigated in systems containing purified sunflower oil (PSO) and water at varying pH, concentration and source of cocoa particles including cocoa powders (CP), cocoa fibre (CF) and cocoa mass (CM). The effect of cocoa particle source, pH and cocoa particle concentration on emulsion stability was evaluated by following changes in characteristic droplet diameter. Size distributions acquired on the emulsions and aqueous cocoa particle suspensions overlapped. Based on cryo-SEM imaging of the emulsions, isolation of cocoa particle fines and a process of washing the cocoa particles to remove any water soluble molecules, it was concluded that the cocoa particle fines not captured by the small angle laser diffraction method employed for sizing, act as Pickering particles. This research has demonstrated a universal nature of a natural food particle to stabilise oil-in-water emulsions not requiring particle modification or adjusting of the solution properties of the emulsion phases. PMID:23851644

Gould, Joanne; Vieira, Josélio; Wolf, Bettina

2013-09-01

322

Destabilization of emulsions by natural minerals.  

PubMed

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

Yuan, Songhu; Tong, Man; Wu, Gaoming

2011-09-15

323

Spectroscopic studies of interactions between C.I. Reactive Orange 16 with alkyltrimethylammonium bromide surfactants  

NASA Astrophysics Data System (ADS)

In the present study, the influence of surfactants on spectral properties of an azo dye in aqueous solutions has been investigated by means of UV-vis spectroscopy in submicellar and micellar concentration range. The spectral signature of the polarity of the azo dye C.I. Reactive Orange 16 (RO16) exhibits sensitivity to the polarity of the dye's environment. This dependence of absorption on microenvironment was used to investigate the ion pair complex formed from electrostatic interaction of a series of alkyltrimethylammonium bromide surfactants (C mTAB, m = 12, 14, 16 and 18) with the anionic azo dye RO16. It was observed that the aggregation of surfactant and dye takes place at surfactant concentration far below the critical micelle concentration of the individual surfactant. Aggregation is reflected by the appearance of a new absorption band in the spectrum of the dye. Spectral behavior of dye-surfactant solution with varying concentration of surfactant confirms that electrostatic interaction between dye and surfactant occurs up to a certain level. Beyond this concentration, with addition of surfactant, micelles occur and all dye molecules are accommodated into a normal micelle as monomeric molecules. The short-range hydro phobic interactions are very important factors as the long-range electrostatic forces on the dye-surfactant aggregation in aqueous solution. The effect of the length of the alkyl chain of the surfactant on the complex formation between cationic surfactant and reactive dye was that the hydrophobicity of alkyl chains plays an important role in complex formation. Going from less hydrophobic solution to the more hydrophobic micellar environment, the occurrence of complex is found at lower surfactant concentration. Because the CMC values of dye-surfactant solution are decreased with increasing alkyl chain length.

Akba?, Halide; Taner, Tanzer

2009-07-01

324

Boiling of an emulsion in a yield stress fluid  

NASA Astrophysics Data System (ADS)

We report the boiling behavior of pentane emulsified in a yield stress fluid, a colloidal clay (Laponite) suspension. We have observed that a superheated state is easily reached: the emulsion, heated more than 50°C above the alkane boiling point, does not boil. Superheating is made possible by the suppression of heterogeneous nucleation in pentane, resulting from the emulsification process, a phenomenon evidenced decades ago in studies of the superheating of two phase fluids. We have furthermore studied the growth of isolated bubbles nucleated in the emulsion. The rate of increase of the bubble radius with time depends on both the temperature and emulsion volume fraction but, rather unexpectedly, does not depend on the fluid rheology. We show that the bubbles grow by diffusion of the alkane through the aqueous phase between liquid droplets and bubbles, analogously to an Ostwald ripening process. The peculiarity of the process reported here is that a layer depleted in oil droplets forms around the bubble, layer to which the alkane concentration gradient is confined. We successfully describe our experimental results with a simple transfer model.

Guéna, Geoffroy; Wang, Ji; D'Espinose, Jean-Baptiste; Lequeux, François; Talini, Laurence

2010-11-01

325

Synergetic effect based gel-emulsions and their utilization for the template preparation of porous polymeric monoliths.  

PubMed

A polymerizable cholesteryl derivative (COA) was synthesized and used as a stabilizer for creating gel-emulsions with water in polymerizable monomers, of which they are styrene (ST), tert-butyl methacrylate (t-BMA), ethylene glycol dimethyl acrylate (EGDMA), and methyl methacrylate (MMA), etc. Interestingly, in addition to COA, the presence of a small amount of Span-80 is a necessity for the formation of the monomers containing gel-emulsions. Unlike conventional ones, the volume fraction of the dispersed phase in the gel-emulsions as created could be much lower than 74%, a critical value for routine gel-emulsions. Stabilization of these gel-emulsions as created has been attributed to the synergetic effect between COA, a typical low-molecular-mass gelator (LMMG), and Span-80, a surfactant, of which the former gels the continuous phase and the latter minimizes the interfacial energy of the continuous phase and the dispersed phase. SEM observation confirmed the network structures of COA in the gel-emulsions. Rheological tests demonstrated that the storage modulus, G', and the yield stress of the gel-emulsions decrease along with increasing the volume fraction of the dispersed phase, water, provided it is not greater than 74%-a result inconsistent with the theory explaining formation of routine gel-emulsions and in support of the conclusion that the systems under study follow a different mechanism. Furthermore, unlike LMMG-based stabilizers reported earlier, the gelator, COA, created in the present study has been functioning not only as a stabilizer but also a monomer. To illustrate the conceptual advantages, the gel-emulsions of water in ST/DVB/AIBN were polymerized. As expected, the densities and internal structures of the monoliths as prepared are highly adjustable, functionalization of the materials with cholesterol has been realized, and at the same time the problem of stabilizer leaking has been avoided. A preliminary test for gas adsorption demonstrated that the monoliths as prepared are good adsorbents for some volatile organic compounds (VOCs), in particular benzene, toluene, ethylbenzene, and xylene-the famous and toxic BTEX. It is believed that the findings reported in the present work provide not only a new strategy for creating novel gel-emulsions but also a new route for functionalizing porous polymeric monoliths. PMID:25338107

Miao, Qing; Chen, Xiangli; Liu, Lingling; Peng, Junxia; Fang, Yu

2014-11-18

326

Forces Between Cationic Surfactants  

NASA Astrophysics Data System (ADS)

Experiments have been performed on a binary mixture of the liposome forming surfactants, DODAB (cationic) and DOPE (zwitterionic), which are used as DNA transfection agents. Langmuir isotherms were studied at different compositions, salt concentrations, and temperatures. The data was used to calculate the excess free energy of mixing. To further understand the non-ideal interactions, the surface forces apparatus (SFA) was utilised to measure the forces between bilayers, under varying conditions, which expose DODAB in the outer monolayers.

Campbell, Samuel; Meyer, Joan; Park, Chad; Lasic, Dan; Israelachvili, Jacob

1996-03-01

327

Study of adsorption kinetics of surfactants onto polyethersulfone membrane surface using QCM-D  

Microsoft Academic Search

The adsorption kinetics of surfactants onto the crystal surface spin-coated with a thin layer of a model membrane material, polyethersulfone was monitored through measurements of frequency and dissipation shifts simultaneously using a quartz crystal microbalance with dissipation (QCM-D) apparatus. In this study, the viscoelastic behaviors of the adsorbed surfactant layers of sodium laureth sulfate, cocamidopropyl betaine and their mixed solution

Sean X. Liu; Jun-Tae Kim

2009-01-01

328

Effect of the initial concentration of emulsifying agents on the ultracentrifugal stability of oil-in-water emulsions  

Microsoft Academic Search

The rate of loss of oil from 50% Nujol-50% water emulsions stabilized with varying concentrations of Tween 20 or Triton X-100,\\u000a and from 50% olive oil-50% water emulsions stabilized with sodium dodecyl sulfate (SDS), was determined by ultracentrifugation\\u000a at 39,460 rpm. In all cases the ultracentrifugal stability increased with increasing initial concentration of emulsifier,\\u000a although, unlike the behavior of Nujol-water-SDS

Kashmiri L. Mittal; Robert D. Vold

1972-01-01

329

Emulsification using highly hydrophilic surfactants improves the absorption of orally administered coenzyme Q10.  

PubMed

Coenzyme Q10 (CoQ10) is an essential component in the electron-transport systems of mitochondria and bacteria and is often used as a supplementary treatment for some diseases. We previously reported that the bioavailability of CoQ10 powder was less than 10%. In this study, we investigated various preparations to improve the intestinal absorption of CoQ10 with focus on the effect of emulsification. We prepared a suspension and some emulsions with four types of surfactants and investigated the plasma concentration profile after oral administration to rats. The absorption of CoQ10 was improved by an emulsion formulation although there was little absorption of CoQ10 when a suspension was administered. However, little CoQ10 was absorbed in the bile duct-ligated group even when the emulsion formulation was administered (about 50% of the control group). Bile and emulsion formulation are essential for absorption of CoQ10. When the preparations containing Tween20 (polysorbate (20) sorbitan monolaurate) and Tween80 (polyoxyethylene (20) sorbitan monooleate) were administered, plasma concentrations of CoQ10 were higher than those obtained with preparations containing Tween65 (polyoxyethylene (20) sorbitan tristearate) and Span20 (sorbitan monolaurate). Tween20 and Tween80 have higher hydrophile-lipophile balance (HLB) values than those Tween65 and Span20. Our study suggests that highly lipophilic compounds like CoQ10 would diffuse the unstirred water layer and would easily access the intestinal apical membrane by an emulsion containing a surfactant with a high HLB value. Attention must be given to CoQ10 supplementation for patients whose bile is not excreted to the intestine such as patients with cholestasis. PMID:24292061

Sato, Yuki; Mutoh, Hanami; Suzuki, Mika; Takekuma, Yoh; Iseki, Ken; Sugawara, Mitsuru

2013-01-01

330

Adsorption of polymer-surfactant mixtures at the oil-water interface.  

PubMed

Small-angle neutron scattering, zeta potential measurements, and dynamic light scattering have been used to investigate the adsorption of polymer-surfactant mixtures at the oil-water interface. The water-hexadecane interface investigated was in the form of small oil-in-water emulsion droplets stabilized by the anionic surfactant sodium dodecyl sulfate, SDS. The impact of the addition of two different cationic polymers, poly(ethyleneimine), PEI, and poly(dimethyldiallylammonium chloride), polydmdaac, on the SDS adsorption at the oil-water interface was studied. For both polymers, the addition of the polymer enhances the SDS adsorption at low SDS concentrations at the oil-water interface due to a strong surface polyelectrolyte-surfactant interaction and complexation, but the effects are not as pronounced as at the air-water interface. For PEI/SDS, the adsorption was largely independent of solution pH and increasing PEI concentration. In marked contrast to the adsorption at the air-water interface, only monolayer adsorption and no multilayer adsorption was observed. For the SDS-polydmdaac mixture, the enhanced SDS adsorption was in the form of a monolayer, and the adsorption increased with increasing polymer concentration. The strong SDS/polydmdaac surface interaction resulted in regions of emulsion instability. The zeta potential measurements showed that the combination of SDS and polydmdaac at the interface resulted in charge reversal at the interface. This correlates with the regions of emulsion stability at both high and low polymer concentrations, such that the instabilities arise in the regions of low or zero surface charge. The results presented and their interpretation represent a development in the understanding of polymer-surfactant adsorption at the oil-water interface. PMID:23025239

Tucker, Ian M; Petkov, Jordan T; Jones, Craig; Penfold, Jeffrey; Thomas, Robert K; Rogers, Sarah E; Terry, Ann E; Heenan, Richard K; Grillo, Isabelle

2012-10-23

331

Emulsions on demand using microsturctured devices  

NASA Astrophysics Data System (ADS)

Emulsions are very common in the field of cosmetics. Unfortunately, most emulsions contain ineffective substances to increase the stability of the products for a long time. These stabilizers can cause some severe healthy problems in several cases. One possible solution is the production of emulsions on demand to prevent the use of stabilizers. Stable emulsion can be achieved if the diameters of the droplets of one solution surrounded by a second solution are smaller than 1?m. Microstructured devices are suited in principle to generate such droplet distributions. Basic task of the development was a micro emulsifier that can be integrated into cosmetic flacons and that can deliver emulsions on demand by pressing a human fingertip onto a part of the flacon. Standardized cosmetic flacons have been used as basic devices. They consist of two separate glass bottles for two different liquid phases and two mechanical pumps integrated in a multifunctional cap. Regarding the viscosity ranges of the two liquids different microemulsifier structures have been developed. External dimensions and connections of the device have been chosen in a way that allows an integration of the devices into the cap. The second design conists of several streaming paths in parallel that allow a reduction of the pressure drop. Furthermore, it consists of three structured silicon chips bonded together. Emulsions with a stability of about 15-30 min have been achieved without any stabilizers. External forces of less than 10N were sufficient to generate emulsions on demand.

Mahe, Christian; Tranchant, Jean Francois; Tromeur, Melanie; Schwesinger, Norbert

2003-01-01

332

Reverse micelles-mediated transport of lipase in liquid emulsion membrane for downstream processing.  

PubMed

This work deals with the downstream processing of lipase (EC 3.1.1.3, from Aspergillus niger) using liquid emulsion membrane (LEM) containing reverse micelles for the first time. The membrane phase consisted of surfactants [cetyltrimethylammonium bromide (CTAB) and Span 80] and cosolvents (isooctane and paraffin light oil). The various process parameters for the extraction of lipase from aqueous feed were optimized to maximize activity recovery and purification fold. The mechanism of lipase transport through LEM consisted of three steps namely solubilization of lipase in reverse micelles, transportation of reverse micelles loaded with lipase through the liquid membrane, and release of the lipase into internal aqueous phase. The results showed that the optimum conditions for activity recovery (78.6%) and purification (3.14-fold) were feed phase ionic strength 0.10 M NaCl and pH 9.0, surfactants concentration (Span 80 0.18 M and CTAB 0.1 M), volume ratio of organic phase to internal aqueous phase 0.9, ratio of membrane emulsion to feed volume 1.0, internal aqueous phase concentration 1.0 M KCl and pH 7.0, stirring speed 450 rpm, and contact time 15 min. This work indicated the feasibility of LEM for the downstream processing of lipase. PMID:23011754

Bhavya, S G; Priyanka, B S; Rastogi, Navin K

2012-01-01

333

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

SciTech Connect

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

P. Somasundaran

2005-04-30

334

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

NASA Astrophysics Data System (ADS)

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

Purohit, Parag

335

Dilution of protein-surfactant complexes: A fluorescence study  

PubMed Central

Dilution of protein–surfactant complexes is an integrated step in microfluidic protein sizing, where the contribution of free micelles to the overall fluorescence is reduced by dilution. This process can be further improved by establishing an optimum surfactant concentration and quantifying the amount of protein based on the fluorescence intensity. To this end, we study the interaction of proteins with anionic sodium dodecyl sulfate (SDS) and cationic hexadecyl trimethyl ammonium bromide (CTAB) using a hydrophobic fluorescent dye (sypro orange). We analyze these interactions fluourometrically with bovine serum albumin, carbonic anhydrase, and beta-galactosidase as model proteins. The fluorescent signature of protein–surfactant complexes at various dilution points shows three distinct regions, surfactant dominant, breakdown, and protein dominant region. Based on the dilution behavior of protein–surfactant complexes, we propose a fluorescence model to explain the contribution of free and bound micelles to the overall fluorescence. Our results show that protein peak is observed at 3 mM SDS as the optimum dilution concentration. Furthermore, we study the effect of protein concentration on fluorescence intensity. In a single protein model with a constant dye quantum yield, the peak height increases with protein concentration. Finally, addition of CTAB to the protein–SDS complex at mole fractions above 0.1 shifts the protein peak from 3 mM to 4 mM SDS. The knowledge of protein–surfactant interactions obtained from these studies provides significant insights for novel detection and quantification techniques in microfluidics. PMID:23868358

Azadi, Glareh; Chauhan, Anuj; Tripathi, Anubhav

2013-01-01

336

Surfactant recycling by solvent extraction in surfactant-aided remediation  

Microsoft Academic Search

As a part of the study on the surfactant-aided remediation of organic contaminants, solvent extraction was investigated to determine its efficiency for used surfactant recycling. The experiments used a glass column 70 cm height with an internal diameter of 3 cm. The convex orifice with four holes (4 mm outer diameter) was installed at the base of the column. Four

Dal-Heui Lee; Robert D. Cody; Dong-Ju Kim

2002-01-01

337

Emulsion Templating of Poly(lactic acid) Particles: Droplet Formation Goran T. Vladisavljevic,*,,  

E-print Network

Emulsion Templating of Poly(lactic acid) Particles: Droplet Formation Behavior Goran T, Belgrade, Serbia ABSTRACT: Monodisperse poly(DL-lactic acid) (PLA) particles of diameters between 11 commonly used biodegradable synthetic polymers for these applications are poly(lactic acid) (PLA) and poly(lactic

338

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

NASA Astrophysics Data System (ADS)

Surfactants are chemically-heterogeneous molecules possessing hydrophilic (head) and hydrophobic (tail) moieties. This dual nature of surfactants leads to interesting phase behavior in aqueous solution as a function of surfactant concentration, including: (i) formation of surfactant monolayers at surfaces and interfaces, and (ii) self-assembly into finite aggregates (micelles) in the bulk solution beyond the critical micelle concentration (cmc). This concentration-dependent phase behavior induces changes in solution properties. For example, the surface activity of surfactants can decrease the surface tension, and self-assembly in bulk solution can lead to changes in viscosity, equivalent conductivity, solubilization capacity, and other bulk properties. These effects make surfactants quite attractive and unique for use in product formulations, where they are utilized as detergents, dispersants, emulsifiers, solubilizers, surface and interfacial tension modifiers, and in other contexts. The specific chemical structure of the surfactant head and tail is essential in determining the overall performance properties of a surfactant in aqueous media. The surfactant tail drives the self-assembly process through the hydrophobic effect, while the surfactant head imparts a certain extent of solubility to the surfactant in aqueous solution through preferential interactions with the hydrogen-bonding network of water. The interplay between these two effects gives rise to the particular phase diagram of a surfactant, including the specific cmc at which micelles begin to form. In addition to serving as a quantitative indicator of micelle formation, the cmc represents a limit to surface monolayer formation, and hence to surface and interfacial tension reduction, because surfactant adsorption at interfaces remains approximately constant beyond the cmc. In addition, the cmc represents the onset of changes in bulk solution properties. This Thesis is concerned with the prediction of cmc's and other micellization properties for a variety of linear and branched surfactant chemical architectures which are commonly encountered in practice. Single-component surfactant solutions are investigated, in order to clarify the specific contributions of the surfactant head and tail to the free energy of micellization, a quantity which determines the cmc and all other aspects of micellization. First, a molecular-thermodynamic (MT) theory is presented which makes use of bulk-phase thermodynamics and a phenomenological thought process to describe the energetics related to the formation of a micelle from its constituent surfactant monomers. Second, a combined computer-simulation/molecular-thermodynamic (CSMT) framework is discussed which provides a more detailed quantification of the hydrophobic effect using molecular dynamics simulations. A novel computational strategy to identify surfactant head and tail using an iterative dividing surface approach, along with simulated micelle results, is proposed. Force-field development for novel surfactant structures is also discussed. Third, a statistical-thermodynamic, single-chain, mean-field theory for linear and branched tail packing is formulated, which enables quantification of the specific energetic penalties related to confinement and constraint of surfactant tails within micelles. Finally, these theoretical and simulations-based strategies are used to predict the micellization behavior of 55 linear surfactants and 28 branched surfactants. Critical micelle concentration and optimal micelle properties are reported and compared with experiment, demonstrating good agreement across a range of surfactant head and tail types. In particular, the CSMT framework is found to provide improved agreement with experimental cmc's for the branched surfactants considered. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

Mendenhall, Jonathan D.

339

Investigation of oil adsorption capacity of granular organoclay media and the kinetics of oil removal from oil-in-water emulsions  

E-print Network

-water emulsion. A kinetic model was developed to examine the time dependent behavior of the oil adsorbing characteristics of the organoclay and to investigate how closely the experimentally obtained data matches the kinetic model. It was found that organoclay...

Islam, Sonia

2007-04-25

340

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

PubMed

The facilitated extraction of Cr(VI) through an emulsion liquid membrane (ELM) was investigated, using tributyl phosphate (TBP) as mobile carrier. The emulsion liquid membrane phase consists of kerosene as diluent, TBP as carrier, SPAN 80 as surfactant and (NH(4))(2)CO(3) solution as stripping phase. The extraction of chromium (VI) has been studied under various experimental conditions and have been determined the influences of surfactant concentration, extractant concentration, stripping solution base concentration, mixing speed, phase ratio, treatment ratio, chromium (VI) and HCl concentrations of the feed solution. It was observed that the extraction rate of Cr(VI) was affected by changes of surfactant concentration, extractant concentration, stripping solution base concentration, and mixing speed. The results obtained showed that by appropriate selection of the extraction and stability conditions, nearly all of chromium (VI) ions present in the feed solution were extracted within 2-4 min. The separation factors of chromium (VI) with respect to cobalt, nickel, copper, cadmium and zinc ions, based on initial feed concentration, have experimentally determined. PMID:20227829

Kumbasar, Recep Ali

2010-06-15

341

About the Role of Surfactants on the Magnetic Control over Liquid Interfaces.  

PubMed

The behavior of magnetically responsive aqueous Fe(III) surfactant solutions at liquid interfaces is analyzed. Such surfactants attracted much attention, because of the ability to manipulate interfaces by magnetic ?elds without any use of magnetic nanoparticles. A detailed analysis of the surface properties proves that the mixing of paramagnetic electrolyte solution with anionic, cationic and nonionic surfactants yields the similar magnetic response and no effect of the surfactant charge can be observed. We conclude that the observed magnetic shiftability of interfaces is caused by a combination of the paramagnetic behavior of the bulk liquid and a reduction of the surface tension. Thus, this work gives an alternative interpretation of the properties of "magnetic surfactants" compared to the ones claimed in the literature. PMID:25198419

Degen, Patrick; Zwar, Elena; Paulus, Michael; Tolan, Metin; Rehage, Heinz

2014-10-01

342

NATURAL SURFACTANTS IN PAPER RECYCLING  

EPA Science Inventory

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

343

ADSORPTION OF SURFACTANT ON CLAYS  

EPA Science Inventory

Surfactants used to enhance remediation of soils by soil washing are often lost in the process. Neither the amount nor the cause of this loss is known. It is assumed that clays present in the soil are responsible for the loss of the surfactant. In this papere, adsorption prope...

344

Kinetic method for determining antioxidant distributions in model food emulsions: distribution constants of t-butylhydroquinone in mixtures of octane, water, and a nonionic emulsifier.  

PubMed

The absence of reliable estimates of distributions of antioxidants in food emulsions hinders the development of a useful method for comparing the efficiencies of antioxidants. Here we describe the application of a pseudophase kinetic model, originally developed for homogeneous microemulsions, to the determination of distribution constants of tert-butylhydroquinone, TBHQ, in a fluid, opaque, model food emulsion composed of the nonionic emulsifier C(12)E(6), octane, and water. This kinetic method should be applicable to a wide variety of charged and uncharged antioxidants in emulsions composed of charged and uncharged emulsifiers. The distribution constants for partitioning of TBHQ between the oil and surfactant film regions, K(O)(I), and the aqueous and surfactant film regions, K(W)(I), were obtained by fitting changes in first-order rate constants, k(obs), with emulsifier volume fraction for the reaction of 4-hexadecyl-2,6-dimethylbenzenediazonium ion, 16-ArN(2)(+), with TBHQ. The rate of formation of the reduced arene product hexadecyl-2,6-dimethylbenzene, 16-ArH, was followed by HPLC. About 90% of the TBHQ is in the surfactant film at about 2% volume fraction of C(12)E(6), which suggests that this region may be the primary site of antioxidant activity for neutral phenolic antioxidants. PMID:12010006

Romsted, Laurence S; Zhang, Jianbing

2002-05-22

345

Influence of droplet size on the efficacy of oil-in-water emulsions loaded with phenolic antimicrobials.  

PubMed

In this study we investigated the effect of droplet size on the antimicrobial activity of emulsions containing two essential oil compounds that are known for their antimicrobial effectiveness: carvacrol and eugenol. Coarse emulsions were prepared by blending a triacylglyceride (Miglyol 812N) containing various concentrations of carvacrol or eugenol (5, 15, 30, 50 wt%) at an oil droplet mass fraction of 10 wt% with an aqueous phase containing 2 wt% Tween 80(®). Premixes were then further dispersed using a high shear blender, a high pressure homogenizer at different pressures or an ultrasonicator to produce droplets with a variety of mean diameters. Microscopy and light scattering storage stability studies over 10 days indicated that manufactured emulsions were stable, i.e. that no aggregation, creaming or other destabilization mechanisms occurred and droplet size distributions remained unchanged. The antimicrobial activity of emulsions was assessed against two model microorganisms, the Gram negative Escherichia coli C 600 and the Gram positive Listeria innocua, by determining growth over time behavior. The analysis yielded the unexpected result that emulsions with larger droplet sizes were more effective at inhibiting growth and inactivating cells than smaller ones. For example, emulsions with a mean oil droplet size of 3000 nm at a concentration of 800 ppm carvacrol completely inhibited L. innocua, while for 80 nm emulsions, only a delay of growth could be observed. Measurements of the concentration of the antimicrobial compounds in the aqueous phase indicated that concentrations of eugenol and carvacrol decreased with decreasing oil droplet sizes. Determination of interfacial tension further showed that eugenol and carvacrol are preferentially located in the oil-water interfaces. Theoretical calculations of Tween 80(®) concentrations needed to saturate interfaces suggested that in small emulsions for the given formulation less Tween 80(®) micelles are present in the aqueous phase. We therefore attribute the fact that antimicrobial nanoemulsions are less active than macroemulsions due to an increased sequestering of antimicrobials in emulsion interfaces and a decreased solubilization in excess Tween 80(®) micelles. PMID:22183117

Terjung, Nino; Löffler, Myriam; Gibis, Monika; Hinrichs, Jörg; Weiss, Jochen

2012-03-01

346

Emulsifier for water-in-oil emulsions  

SciTech Connect

This patent describes a water-in-oil emulsion. It comprises: a continuous oil phase, a discontinuous aqueous phase, and an emulsion stabilizing amount of a thermally altered lecithin composition which has been prepare by heating lecithin at a temperature in the range of from about 100{degrees}C, to about 250{degrees}C, for a period of time ranging from about 15 to about 480 minutes.

Weete, J.D.; Griffith, G.L.

1990-07-24

347

On-line surfactant monitoring  

SciTech Connect

This group has developed a process to extract metal ions from dilute aqueous solutions. The process uses water soluble polymers to complex metal ions. The metal/polymer complex is concentrated by ultrafiltration and the metals are recovered by a pH adjustment that frees the metal ions. The metal ions pass through the ultrafiltration membrane and are recovered in a concentrated form suitable for reuse. Surfactants are present in one of the target waste streams. Surfactants foul the costly ultrafiltration membranes. It was necessary to remove the surfactants before processing the waste stream. This paper discusses an on-line device the authors fabricated to monitor the process stream to assure that all the surfactant had been removed. The device is inexpensive and sensitive to very low levels of surfactants.

Mullen, K.I.; Neal, E.E.; Soran, P.D.; Smith, B. [Los Alamos National Lab., NM (United States). Chemical Science and Technology Div.

1995-04-01

348

Polyurethane and polyurea nanoparticles based on polyoxyethylene castor oil derivative surfactant suitable for endovascular applications.  

PubMed

The design of new, safe and effective nanotherapeutic systems is an important challenge for the researchers in the nanotechnology area. This study describes the formation of biocompatible polyurethane and polyurea nanoparticles based on polyoxyethylene castor oil derivative surfactant formed from O/W nano-emulsions by polymerization at the droplet interfaces in systems composed by aqueous solution/Kolliphor(®) ELP/medium chain triglyceride suitable for intravenous administration. Initial nano-emulsions incorporating highly hydrophilic materials were prepared by the phase inversion composition (PIC) method. After polymerization, nanoparticles with a small particle diameter (25-55 nm) and low polydispersity index were obtained. Parameters such as concentration of monomer, O/S weight ratio as well as the polymerization temperature were crucial to achieve a correct formation of these nanoparticles. Moreover, FT-IR studies showed the full conversion of the monomer to polyurethane and polyurea polymers. Likewise the involvement of the surfactant in the polymerization process through their nucleophilic groups to form the polymeric matrix was demonstrated. This could mean a first step in the development of biocompatible systems formulated with polyoxyethylene castor oil derivative surfactants. In addition, haemolysis and cell viability assays evidenced the good biocompatibility of KELP polyurethane and polyurea nanoparticles thus indicating the potential of these nanosystems as promising drug carriers. PMID:24275445

Morral-Ruíz, Genoveva; Melgar-Lesmes, Pedro; García, María Luísa; Solans, Conxita; García-Celma, María José

2014-01-30

349

Intravenous lipid emulsion in clinical toxicology  

PubMed Central

Intravenous lipid emulsion is an established, effective treatment for local anesthetic-induced cardiovascular collapse. The predominant theory for its mechanism of action is that by creating an expanded, intravascular lipid phase, equilibria are established that drive the offending drug from target tissues into the newly formed 'lipid sink'. Based on this hypothesis, lipid emulsion has been considered a candidate for generic reversal of toxicity caused by overdose of any lipophilic drug. Recent case reports of successful resuscitation suggest the efficacy of lipid emulsion infusion for treating non-local anesthetic overdoses across a wide spectrum of drugs: beta blockers, calcium channel blockers, parasiticides, herbicides and several varieties of psychotropic agents. Lipid emulsion therapy is gaining acceptance in emergency rooms and other critical care settings as a possible treatment for lipophilic drug toxicity. While protocols exist for administration of lipid emulsion in the setting of local anesthetic toxicity, no optimal regimen has been established for treatment of acute non-local anesthetic poisonings. Future studies will shape the evolving recommendations for lipid emulsion in the setting of non-local anesthetic drug overdose. PMID:20923546

2010-01-01

350

Water in oil emulsion stabilized by tadpole-like single chain polymer nanoparticles and its application in biphase reaction.  

PubMed

In this study, tadpole-like single chain polymer nanoparticles (TSCPNs) were efficiently synthesized by intramolecularly cross-linking P4VP block of commercial block polymer of PMMA2250-b-P4VP286 in N,N-dimethylformamide using propargyl bromide as cross-linking agent. The intramolecular cross-linking reaction led to the production of TSCPNs with a linear tail and a cross-linked head. The as-prepared TSCPNs were then applied as emulsifier to stabilize water in chlorobenzene emulsion, and an extremely stabilized water in oil (W/O) emulsion was generated at a low TSCPNs concentration. The TSCPNs concentration was as low as 0.0075 wt % versus total weight of water and chlorobenzene for emulsion formation. The emulsifying performance of TSCPNs was better than that of low molecular surfactant, such as Span-80. The generated W/O emulsion provided an ideal medium for the reduction of oil-soluble p-nitroanisole by water-soluble sulfide to p-anisidine, an effective contact problem between the two reactants with different solubility was well solved through interfacial reaction. PMID:24707798

Xu, Fugui; Fang, Zhihui; Yang, Duanguang; Gao, Yong; Li, Huaming; Chen, Daoyong

2014-05-14

351

Transient Exposure of Pulmonary Surfactant to Hyaluronan Promotes Structural and Compositional Transformations into a Highly Active State*  

PubMed Central

Pulmonary surfactant is a lipid-protein complex that lowers surface tension at the respiratory air-liquid interface, stabilizing the lungs against physical forces tending to collapse alveoli. Dysfunction of surfactant is associated with respiratory pathologies such as acute respiratory distress syndrome or meconium aspiration syndrome where naturally occurring surfactant-inhibitory agents such as serum, meconium, or cholesterol reach the lung. We analyzed the effect of hyaluronan (HA) on the structure and surface behavior of pulmonary surfactant to understand the mechanism for HA-promoted surfactant protection in the presence of inhibitory agents. In particular, we found that HA affects structural properties such as the aggregation state of surfactant membranes and the size, distribution, and order/packing of phase-segregated lipid domains. These effects do not require a direct interaction between surfactant complexes and HA and are accompanied by a compositional reorganization of large surfactant complexes that become enriched with saturated phospholipid species. HA-exposed surfactant reaches very high efficiency in terms of rapid and spontaneous adsorption of surfactant phospholipids at the air-liquid interface and shows significantly improved resistance to inactivation by serum or cholesterol. We propose that physical effects pertaining to the formation of a meshwork of interpenetrating HA polymer chains are responsible for the changes in surfactant structure and composition that enhance surfactant function and, thus, resistance to inactivation. The higher resistance of HA-exposed surfactant to inactivation persists even after removal of the polymer, suggesting that transient exposure of surfactant to polymers like HA could be a promising strategy for the production of more efficient therapeutic surfactant preparations. PMID:23983120

Lopez-Rodriguez, Elena; Cruz, Antonio; Richter, Ralf P.; Taeusch, H. William; Perez-Gil, Jesus

2013-01-01

352

Emulsion Paint of Aromatic Petroleum Resin II. Improvement On Poor Corrosion Resistance of Emulsion Paint Film  

Microsoft Academic Search

Poor corrosion resistance of an emulsion paint film using the emulsion produced from an industrially produced aromatic petroleum resin with a thermally denaturated linseed oil, as corrosion inhibitor for metal plates, was improved much better by use of a suitable nonionic emulsifier Emulgen A-90 rather than cationic and anionic ones as wetting agent for pigments and by addition of a

Yoshiyuki Iwase

1980-01-01

353

Cold processed oil-in-water emulsions for dermatological purpose: formulation design and structure analysis.  

PubMed

The aim of this work is to develop, optimize and characterize cold process emulsions that are stable at acidic pH. The main surfactant was selected according to the hydrophilic lipophilic balance (HLB) concept and surface tension, whereas polymers were selected by viscoelastic measurements and analytical centrifugation. It was showed that the inclusion of methyl vinyl ether/maleic anhydride copolymer crosslinked with decadiene (PVM/MA) increased the storage modulus (G') of the gels (23.9-42.1?Pa) two-fold and the droplet migration decreased from 3.66% to 0.95%/h. Cetrimide was selected as a preservative based on its microbiological results and additional contribution to the stability of the emulsions. Four emulsions were developed that differed by the co-emulsifier used (PEG-20 glyceril laurate and polyglyceryl-4-isostearate) and the glycol (2-methyl-2,4-pentanediol and ethoxydiglycol). Viscoelastic measurements and droplet size/microscopic analysis showed that the structure of PEG-20 glyceril laurate emulsion (?'?=?76.0?Pa.s at 0.01?Hz and 32.9?±?3.7?µm, respectively) was stronger compared to polyglyceryl-4-isostearate (?'?=?37.4?Pa.s at 0.01?Hz and 37.8?±?15.7?µm, respectively). Differential scanning calorimetry (DSC) results were in accordance with the latter and showed that PEG-20 glyceril laurate with 2-methyl-2,4-pentanediol corresponded to the strongest structure (|224.4|?W?°C?g(-1)). This cold process allowed a total production savings of more than 17% when compared to the traditional hot process. PMID:23617265

Raposo, Sara; Salgado, Ana; Eccleston, Gillian; Urbano, Manuela; Ribeiro, Helena M

2014-06-01

354

Electrical stability, emulsion stability, and wettability of invert oil-based muds  

SciTech Connect

Until now, drilling-fluid specialists measured trends in the electrical stability (ES) test to decide the appropriate emulsifier treatment for invert-emulsion oil-based muds without knowing what the ES test was measuring. This paper describes what happens in a mud during an ES test, how mud composition affects trends in the ES measurements, and how observed trends can be used to deduce mud-emulsion stability and oil wettability. During an ES test, electrical breakdown is induced in the mud between the electrodes. This process was observed, with an optical microscope, to involve formation of a conductive bridge composed of aqueous fluid and particulate matter. Experiments showed that water forms the conductive pathway in the bridge, whereas the solids appear to be involved only as carriers of the water. E[sub o], the voltage at which the conductive bridge is formed and the current rises abruptly, was found to be a function of the viscosity and the types and concentrations of solids, aqueous fluid, and emulsifiers (surfactants). These trends are consistent with a theoretical expression for breakdown of particulate-contaminated dielectric fluids, which suggests that the E[sub o] of a mud is an absolute measure of its emulsion stability but only a relative measure of its oil-wetting tendency. Trends in E[sub o] are also consistent in most cases with other field indicators of emulsion stability, such as high-temperature, high-pressure (HTHP) fluid loss. Anomalies in E[sub o] trends are explained in terms of a physicochemical model for electrical breakdown.

Growcock, F.B.; Ellis, C.F.; Schmidt, D.D.

1994-03-01

355

Development of cyclosporine A-loaded dry-emulsion formulation using highly purified glycerol monooleate for safe inhalation therapy.  

PubMed

The main objective of this study was to improve the safety and oxidative stability of glycerol monooleate (GMO)-based dry-emulsion (DE) formulation containing cyclosporine A (CsA) for inhalation therapy. GMO or highly purified GMO (hpGMO) was used as surfactant for the DE formulations (GMO/DE or hpGMO/DE), the toxicological and physicochemical properties of which were characterized with a focus on oxidative stability, in vitro/in vivo toxicity, and dissolution property. Incubation of GMO at oxidation accelerating conditions for 10 days at 60°C resulted in the formation of lipid peroxides as evidenced by increased malondialdehyde (111 ?mol/mg); however, hpGMO samples exhibited increase of only 20.7 ?mol/mg in malondialdehyde level. No significant acute cytotoxicity was observed in rat alveolar L2 cells exposed to hpGMO (0.28mM), and intratracheal administration of hpGMO powder in rats did not cause an increase of the plasma LDH level. The hpGMO/DE exhibited marked improvement in dissolution behavior of CsA, and stable fine micelles with a mean diameter of 320 nm were formed when suspended in water. A respirable powder formulation of hpGMO/DE (hpGMO/DE-RP) was newly prepared, and its in vitro inhalation property and in vivo efficacy were also evaluated. The hpGMO/DE-RP exhibited high dispersibility in laser diffraction analysis and significantly improved potency to attenuate recruitment of inflammatory cells into airway and thickening of airway wall in an animal model. Thus, the strategic use of hpGMO would improve oxidative stability and local toxicity compared with a GMO-based DE formulation, and its application to RP formulation could be a promising approach for effective inhalation therapy. PMID:23528280

Sato, Hideyuki; Ogawa, Kumiko; Kojo, Yoshiki; Kawabata, Yohei; Mizumoto, Takahiro; Yamada, Shizuo; Onoue, Satomi

2013-05-01

356

High- and low-molecular-mass microbial surfactants.  

PubMed

Microorganisms synthesize a wide variety of high- and low-molecular-mass bioemulsifiers. The low-molecular-mass bioemulsifiers are generally glycolipids, such as trehalose lipids, sophorolipids and rhamnolipids, or lipopeptides, such as surfactin, gramicidin S and polymyxin. The high-molecular-mass bioemulsifiers are amphipathic polysaccharides, proteins, lipopolysaccharides, lipoproteins or complex mixtures of these biopolymers. The low-molecular-mass bioemulsifiers lower surface and interfacial tensions, whereas the higher-molecular-mass bioemulsifiers are more effective at stabilizing oil-in-water emulsions. Three natural roles for bioemulsifiers have been proposed: (i) increasing the surface area of hydrophobic water-insoluble growth substrates; (ii) increasing the bioavailability of hydrophobic substrates by increasing their apparent solubility or desorbing them from surfaces; (iii) regulating the attachment and detachment of microorganisms to and from surfaces. Bioemulsifiers have several important advantages over chemical surfactants, which should allow them to become prominent in industrial and environmental applications. The potential commercial applications of bioemulsifiers include bioremediation of oil-polluted soil and water, enhanced oil recovery, replacement of chlorinated solvents used in cleaning-up oil-contaminated pipes, vessels and machinery, use in the detergent industry, formulations of herbicides and pesticides and formation of stable oil-in-water emulsions for the food and cosmetic industries. PMID:10499255

Rosenberg, E; Ron, E Z

1999-08-01

357

The Influence of Surfactant on PLGA Microsphere Glass Transition and Water Sorption: Remodeling the Surface Morphology to Attenuate the Burst Release  

Microsoft Academic Search

\\u000a Purpose  The stability of protein unloaded and loaded poly(lactic-co-glycolic acid) (PLGA) microspheres fabricated with surfactant\\u000a was challenged through exposure to environmental conditions of different relative humidity.\\u000a \\u000a \\u000a \\u000a Methods  Polyvinyl alcohol (PVA) or Triton X-100 was added to the primary emulsion of the double-emulsion solvent evaporation technique.\\u000a After storage at ambient humidity and 75% relative humidity, the mechanical stability of the polymer was tested

C. Bouissou; J. J. Rouse; R. Price; C. F. van der Walle

2006-01-01

358

Small-angle neutron scattering study of the structure of mixed micellar solutions based on nonionic and two cationic surfactants  

NASA Astrophysics Data System (ADS)

The aggregation in mixed water systems based on nonionic surfactant, i.e., heptaethylene glycol monotetradecyl ether (C14E7), and cationic surfactants, i.e., cetyltrimethylammonium bromide (CTAB) and cetyltrimethylammonium chloride (CTAC), has been investigated using the small-angle neutron scattering method. The preliminary results of the study of the behavior of C14E7 aqueous solutions (for a concentration of 0.17%) when adding various small amounts of classical cationic surfactants (CTAB and CTAC) have been presented.

Rajewska, A.; Medrzycka, K.; Hallmann, E.

2014-01-01

359

Monte Carlo study of surfactant adsorption on heterogeneous solid surfaces.  

PubMed

The equilibrium between free surfactant molecules in aqueous solution and adsorbed layers on structured solid surfaces is investigated by lattice Monte Carlo simulation. The solid surfaces are composed of hydrophilic and hydrophobic surface regions. The structures of the surfactant adsorbate above isolated surface domains and domains arranged in a checkerboard-like pattern are characterized. At the domain boundary, the adsorption layers display a different behavior for hydrophilic and hydrophobic surface domains. For the checkerboard-like surfaces, additional adsorption takes place at the boundaries between surface domains. PMID:15697319

Reimer, U; Wahab, M; Schiller, P; Mögel, H-J

2005-02-15

360

Structural Studies of Protein-Surfactant Complexes  

SciTech Connect

The structure of protein-surfactant complexes of two proteins bovine serum albumin (BSA) and lysozyme in presence of anionic surfactant sodium dodecyl sulfate (SDS) has been studied using small-angle neutron scattering (SANS). It is observed that these two proteins form different complex structures with the surfactant. While BSA protein undergoes unfolding on addition of surfactant, lysozyme does not show any unfolding even up to very high surfactant concentrations. The unfolding of BSA protein is caused by micelle-like aggregation of surfactant molecules in the complex. On the other hand, for lysozyme protein there is only binding of individual surfactant molecules to protein. Lysozyme in presence of higher surfactant concentrations has protein-surfactant complex structure coexisting with pure surfactant micelles.

Chodankar, S. N.; Aswal, V. K.; Wagh, A. G. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400 085 (India)

2008-03-17

361

Pulmonary surfactant for neonatal respiratory disorders.  

PubMed

Surfactant therapy has revolutionized neonatal care and is used routinely for preterm infants with respiratory distress syndrome. Recent investigation has further elucidated the function of surfactant-associated proteins and their contribution toward surfactant and lung immune defense functions. As the field of neonatology moves away from intubation and mechanical ventilation of preterm infants at birth toward more aggressive use of nasal continuous positive airway pressure, the optimal timing of exogenous surfactant therapy remains unclear. Evidence suggests that preterm neonates with bronchopulmonary dysplasia and prolonged mechanical ventilation also experience surfactant dysfunction; however, exogenous surfactant therapy beyond the first week of life has not been well studied. Surfactant replacement therapy has been studied for use in other respiratory disorders, including meconium aspiration syndrome and pneumonia. Commercial surfactant preparations currently available are not optimal, given the variability of surfactant protein content and their susceptibility to inhibition. Further progress in the treatment of neonatal respiratory disorders may include the development of "designer" surfactant preparations. PMID:12640270

Merrill, Jeffrey D; Ballard, Roberta A

2003-04-01

362

Quick setting anionic bituminous emulsions  

SciTech Connect

A bituminous emulsion is described comprising: (a) from about 50% to about 70% by weight of non-coal tar bitumen; (b) from about 0.1% to about 3% by weight of an emulsifier which is the amine salt of an alkylbenzene sulfonic acid in which the alkyl contains from about 8 to about 16 carbon atoms. The salt-forming amine is selected from amines having the formula: wherein R/sub 1/ is selected from the group consisting of aminoalkyl and monohydroxyalkyl radicals containing from 1 to about 6 carbon atoms and R/sub 2/ and R/sub 3/ are each selected from the group consisting of hydrogen, alkyl, aminoalkyl and monohydroxyalkyl radicals containing from 1 to about 6 carbon atoms and wherein the molar ratio of alkylbenzene sulfonic acid to amine in the amine salt is 1:1; and (c) from about 30% to about 50% water, the composition having a pH of from about 2.5 to about 10.

Russell, A.

1987-04-14

363

Analysis of electrical property changes of skin by oil-in-water emulsion components  

PubMed Central

Synopsis ObjectivesAs the ‘Dry Skin Cycle’ produces continuous deterioration, cosmetic xerosis (flaky, dry skin) is one of the major concerns to most consumers. The purpose of this study was to investigate the moisturizing effect of oil-in-water (O/W) emulsion components. There are numerous types of oils, waxes, polyols and surfactants used as ingredients in skincare products. However, the moisturizing effect of each ingredient and understanding each use to make an effective moisturizing products are still not well understood. Methods To provide answers to these questions, we investigated the moisturizing effect of widely used 41 components (four different classes) in a simple O/W emulsion using capacitance methods. 106 different single oils, and combinations of oil with oil, wax, humectants, and surfactant were formulated and tested. Results In this study, we found that most of the O/W emulsion components had hydration effects on the skin. (i) The average relative water content increase (RWCI) rate of a single oil-based emulsion was 11.8 ± 5.2% (SE) and 7.9 ± 6.0% (SE) at 3 and 6 h, respectively. (ii) An oil combination emulsion showed an average RWCI rate similar to that of a single oil-based emulsion, 12.6 ± 6.0% (SE) and 12.1 ± 6.4% (SE) at 3 and 6 h, respectively (iii) A combination of waxes with oil showed an average RWCI rate of 16 ± 5.6% (SE) and 12.4 ± 4.5% (SE) at 3 and 6 h, respectively. (iv) Humectant combinations showed the highest average RWCI rate 28 ± 7.3% (SE) and 22.2 ± 7.5% (SE) at 3 and 6 h, respectively (v) Surfactant combinations had an average RWCI of 10.8 ± 4.5% (SE) and 6.0 ± 4.0% (SE) at 3 and 6 h, respectively. Conclusion Interestingly, it was difficult to find moisturizing power differences among samples in the same group. Only the humectants group showed significant differences among samples. Glycerine and urea showed significant skin hydration effects compared with other humectants. We also found a significant moisturizing effect by analysing the chemical functional groups; amide class had a higher hydration effect than betaines and disaccharides in humectants combination. Résumé Objectif Puisque le «cycle de la peau sèche” produit une détérioration continue, la xérose cosmétique (squameuse, peau sèche) est l’une des préoccupations majeures pour la plupart des consommateurs. Le but de cette étude était d’étudier l’effet hydratant des composants d’émulsions H / E. Il existe de nombreux types d’huiles, des cires, de polyols, et des tensioactifs utilisés comme ingrédients dans les produits de soins de la peau. Cependant, l’effet hydratant de chaque ingrédient et de leur utilisation dans des produits hydratants efficaces ne sont pas encore bien compris. MethodesPour apporter des réponses à ces questions, nous avons étudié l’effet hydratant des 41 éléments (4 classes différentes) largement utilisés dans une émulsion simple O/W en utilisant des méthodes de capacitance. 106 huiles individuelles différentes et des combinaisons d’huile avec de l’huile, de la cire, des humectants, et de tensioactifs ont été formulées et testées. ResultatsDans cette étude, nous avons constaté que la plupart des composants des émulsions huile-dans-eau (H/E) possédaient des effets d’hydratation de la peau. (i) Le taux moyen d’augmentation d’eau (RWCI = relative water content increase) d’une émulsion à base d’une seule huile était de 11,8 ± 5,2% (SE) et de 7,9 ± 6,0% (SE) à 3 et 6 h, respectivement. (ii) Une émulsion de combinaison d’huile montrait une RWCI similaire à celle d

Jeong, CB; Han, JY; Cho, JC; Suh, KD; Nam, GW

2013-01-01

364

Mineral-Surfactant Interactions for Minimum Reagents Precipitation and Adsorption for Improved Oil Recovery  

SciTech Connect

Chemical EOR can be an effective method for increasing oil recovery and reducing the amount of produced water; however, reservoir fluids are chemically complex and may react adversely to the polymers and surfactants injected into the reservoir. While a major goal is to alter rock wettability and interfacial tension between oil and water, rock-fluid and fluid-fluid interactions must be understood and controlled to minimize reagent loss, maximize recovery and mitigate costly failures. The overall objective of this project was to elucidate the mechanisms of interactions between polymers/surfactants and the mineral surfaces responsible for determining the chemical loss due to adsorption and precipitation in EOR processes. The role of dissolved inorganic species that are dependent on the mineralogy is investigated with respect to their effects on adsorption. Adsorption, wettability and interfacial tension are studied with the aim to control chemical losses, the ultimate goal being to devise schemes to develop guidelines for surfactant and polymer selection in EOR. The adsorption behavior of mixed polymer/surfactant and surfactant/surfactant systems on typical reservoir minerals (quartz, alumina, calcite, dolomite, kaolinite, gypsum, pyrite, etc.) was correlated to their molecular structures, intermolecular interactions and the solution conditions such as pH and/or salinity. Predictive models as well as general guidelines for the use of polymer/surfactant surfactant/surfactant system in EOR have been developed The following tasks have been completed under the scope of the project: (1) Mineral characterization, in terms of SEM, BET, size, surface charge, and point zero charge. (2) Study of the interactions among typical reservoir minerals (quartz, alumina, calcite, dolomite, kaolinite, gypsum, pyrite, etc.) and surfactants and/or polymers in terms of adsorption properties that include both macroscopic (adsorption density, wettability) and microscopic (orientation/conformation of the adsorbed layers), as well as precipitation/abstraction characteristics. (3) Investigation of the role of dissolved species, especially multivalent ions, on interactions between reservoir minerals and surfactants and/or polymers leading to surfactant precipitation or activated adsorption. (4) Solution behavior tests--surface tension, interaction, ultra filtration, and other tests. (5) Surfactant-mineral interactions relative to adsorption, wettability, and electrophoresis. (6) Work on the effects of multivalent ions, pH, temperature, salinity, and mixing ratio on the adsorption. Developments of adsorption models to explain interactions between surfactants/polymers/minerals. (7) General guidelines for the use of certain surfactants, polymers and their mixtures in micelle flooding processes.

P. Somasundaran

2008-09-20

365

Factors affecting the emulsifying and rheological properties of gum acacia in beverage emulsions  

Microsoft Academic Search

Gum acacia, a natural hydrocolloid, is extensively used as an emulsifier\\/stabilizer in beverage emulsions. Factors that may affect emulsion formation, emulsion stability and viscosity of the emulsion concentrate were studied to assess their significance, including proximal composition of the gum (protein content and mineral content), gum processing prior to emulsion preparation (pasteurization and demineralization), and pH of the dilute emulsion.

R. A Buffo; G. A Reineccius; G. W Oehlert

2001-01-01

366

Weakly breaking waves in the presence of surfactant micelles  

NASA Astrophysics Data System (ADS)

Mechanically generated weakly breaking waves were studied experimentally in clean water and water with a soluble surfactant whose bulk concentration was above the critical micelle concentration (CMC). For the surfactant case, the breaker, which forms a surface-tension-dominated spilling breaker in clean water [wave frequencies 1.42 to 1.15Hz , see Duncan , J. Fluid Mech. 379, 191 (1999)], ranges from a spiller at the highest frequency to an overturning wave with a plunging microjet at the lowest frequency. It is shown that this behavior is consistent with that of a wave in a pure liquid with a lower surface tension than water rather than water with a surfactant monolayer. The analysis of the geometrical characteristics of the breaking surface generated by the jet impact on the front face of the wave crest indicates a patch of more violent turbulence suggesting an increase of air-sea transfer compared to the clean water case.

Liu, Xinan; Duncan, James H.

2007-12-01

367

High pressure-resistant nonincendive emulsion explosive  

DOEpatents

An improved emulsion explosive composition including hollow microspheres/bulking agents having high density and high strength. The hollow microspheres/bulking agents have true particle densities of about 0.2 grams per cubic centimeter or greater and include glass, siliceous, ceramic and synthetic resin microspheres, expanded minerals, and mixtures thereof. The preferred weight percentage of hollow microspheres/bulking agents in the composition ranges from 3.0 to 10.0 A chlorinated paraffin oil, also present in the improved emulsion explosive composition, imparts a higher film strength to the oil phase in the emulsion. The emulsion is rendered nonincendive by the production of sodium chloride in situ via the decomposition of sodium nitrate, a chlorinated paraffin oil, and sodium perchlorate. The air-gap sensitivity is improved by the in situ formation of monomethylamine perchlorate from dissolved monomethylamine nitrate and sodium perchlorate. The emulsion explosive composition can withstand static pressures to 139 bars and dynamic pressure loads on the order of 567 bars.

Ruhe, Thomas C. (Duquesne, PA); Rao, Pilaka P. (Baghlingampalli, IN)

1994-01-01

368

Partitioning of non-ionic surfactants between water and non-aqueous phase liquids (NAPLs) of chlorinated organics  

NASA Astrophysics Data System (ADS)

Due to the hydrophobic nature, chlorinated organic compounds penetrate soil and groundwater to form non-aqueous phase liquids (NAPLs). At the sites contaminated with such NAPLs, thus, surfactants are applied to increase the aqueous solubility of chlorinated organics via micellar solubilization. However, a portion of surfactants can be partitioned into NAPL phases by forming reverse micelles within them. Consequently, lesser amounts of surfactants are available for the micellar solubilization of chlorinated organics in the aqueous phase. In this study, we investigated the partitioning behavior of non-ionic surfactants (Tween 20, Tween 40, Tween 80, and Triton X-100) between water and a NAPL phase consisting of tetrachloroethylene (PCE), trichloroethylene (TCE), or chloroform (CF). According to the experimental results, the partitioning of surfactants in the water-NAPL systems was found to follow linear or Langmuir-type isotherms. Regardless of type of surfactants, the partitioning loss of surfactants into NAPLs became greater with the more hydrophilic (i.e., the lower water-NAPL interfacial tension) chlorinated organics: PCE < TCE < CF. Notably, the partitioning of all Tween surfactants into the NAPLs consisting of the least hydrophilic PCE was minimal. The partitioning behavior among different surfactants was somewhat complicated. The partitioning extent into CF-NAPLs increased in the order of Tween 20 < Tween 40 < Tween 80 << Triton X-100, suggesting that the greater partitioning occurred with the more hydrophobic (i.e., the lower hydrophilic-lipophilic balance, HLB) surfactant. Consistent with this postulation, the surfactant partitioning into PCE-NAPLs showed the similar trend. In case of TCE-NAPLs, however, the more hydrophobic Tween 40 was partitioned to a less extent than Tween 20. Therefore, the specific interaction of a NAPL-surfactant pair as well as their individual properties should be considered when selecting an effective surfactant for the remediation of a NAPL-contaminated site.

KANG, S.; Jeong, H. Y.

2013-12-01

369

Surfactant-activated microgels: a new pathway to rheology modification.  

PubMed

Alkali swellable microgels are widely used to control rheology of formulated products containing surfactants. However, formulations based on these pH-responsive polymers show undesirably large changes in yield stress in a range of pH close to the pKa of the acid group. Analysis of the behavior of a cross-linked copolymer of ethyl acrylate and methacrylic acid in the nonionized form (at pH below the pKa of methacrylic acid) in the presence of sodium dodecyl sulfate shows surfactant-mediated swelling (an increase in particle diameter by over 2.5×) and a peak in zero-shear viscosity versus surfactant concentration indicating surfactant-mediated interaction of the swollen microgels. On the basis of these results, we demonstrate a new class of nonionic microgels composed of hydrophobic alkyl acrylates and hydrophilic hydroxyalkyl esters that utilize the effects of surfactant-mediated swelling and interaction to provide pH-independent rheological properties. PMID:24304130

Chari, Krishnan; Hsu, Raymond; Bhargava, Prachur; Figura, Brian; Yang, Wayne; Park, Jung Hyun; Clifford, Ted; Kadir, Murat

2013-12-17

370

Properties of clutch using thixotropic MR fluid with surfactants  

NASA Astrophysics Data System (ADS)

Properties of a magnetorheological (MR) clutch have been investigated using newly developed MR fluids (suspensions) which consist of the carbonyl iron particles and thixotropic carrier fluid. The carrier fluid is composed of a rapeseed ester oil (vegetable oil) and synthetic smectite. The dependences of an output torque of the clutch on the applied magnetic field were examined under a fixed input torque for different densities of particles, surfactant or smectite in the MR fluids. The thixotropic behavior of the carrier fluids also was evaluated using a rheometer of the coaxial cylinder type. As for the MR fluid of 81wt% particles with 7wt% smectite, the output torque of the clutch increased with increases of the surfactant in the range of 0 to 5 wt%. On the other hand, the thixotropic effect was lost gradually with increase of the surfactant over 5wt% at the smectite concentration of 7wt%, but the output torque increased with increasing the surfactant accompanying by particles sedimentation. The sedimentation could be suppressed by the increase of the smectite concentration without decreasing of the output torque. As a result, the output torque reached to 57Nm by controlling the content of the surfactant and smectite in the MR fluids.

Takata, Shinzo; Hosoo, Kenjiro; Inoue, Yoshimasa; Hanaoka, Ryoichi; Fukami, Tadashi; Shima, Kazuo

2007-07-01

371

Surface properties of Gemini surfactants with pyrrolidinium head groups.  

PubMed

Gemini surfactants C(n)-4-(n)PB (where n represents the alkyl chain length of 10, 12, 14 and 16) were synthesized and characterized. Their surface activity, thermodynamic properties, and aggregation behavior were investigated by means of surface tension, electrical conductivity, and steady-state fluorescence. It was found that the Gemini surfactants C(n)-4-(n)PB have superior surface activity to their corresponding monomer surfactants C(n)MPB as expected. Additionally, these compounds have lower cmc and surface tension in comparison with conventional cationic Gemini surfactants m-4-m. Thermodynamic parameters (?G(m)(0),?H(m)(0),T?S(m)(0)) show that the micellization is an entropy driven process with shorter hydrophobic chain lengths but instead is enthalpy driven for longer hydrophobic chain lengths. The effect of the hydrophobic alkyl chain length and the addition of inorganic salt NaBr on the surface activity and micellization are in line with the conventional cationic Gemini surfactants. PMID:22261268

Cai, Bo; Li, Xuefeng; Yang, Yi; Dong, Jinfeng

2012-03-15

372

Mixed micellization of gemini and conventional surfactant in aqueous solution: A lattice Monte Carlo simulation.  

PubMed

In the current study, we have investigated the micellization of pure gemini surfactants and a mixture of gemini and conventional surfactants using a 3D lattice Monte Carlo simulation method. For the pure gemini surfactant system, the effects of tail length on CMC and aggregation number were studied, and the simulation results were found to be in excellent agreement with the experimental results. For a mixture of gemini and conventional surfactants, variations in the mixed CMC, interaction parameter ?, and excess Gibbs free energy G(E) with composition revealed synergism in micelle formation. Simulation results were compared to estimations made using regular solution theory to determine the applicability of this theory for non-ideal mixed surfactant systems. A large discrepancy was observed between the behavior of parameters such as the activity coefficients fi and the excess Gibbs free energy G(E) and the expected behavior of these parameters as predicted by regular solution theory. Therefore, we have used the modified version of regular solution theory. This three parameter model contains two parameters in addition to the interaction parameters: the size parameter, ?, which reflects differences in the size of components, and the packing parameter, P*, which reflects nonrandom mixing in mixed micelles. The proposed model provides a good description of the behavior of gemini and conventional surfactant mixtures. The results indicated that as the chain length of gemini surfactants in mixture is increased, the size parameter remains constant while the interaction and packing parameters increase. PMID:25218241

Gharibi, Hussein; Khodadadi, Zahra; Mousavi-Khoshdel, S Morteza; Hashemianzadeh, S Majid; Javadian, Soheila

2014-09-01

373

Surfactant instabilities on thin films  

E-print Network

The deposition of a surfactant drop over a thin liquid film may be accompanied by a fingering instability. In this work, we present experimental results which identify the critical parameters that govern the shape and ...

Aessopos, Angelica

2005-01-01

374

Study of the Formation and Solution Properties of Worm-Like Micelles Formed Using Both N-Hexadecyl-N-Methylpiperidinium Bromide-Based Cationic Surfactant and Anionic Surfactant  

PubMed Central

The viscoelastic properties of worm-like micelles formed by mixing the cationic surfactant N-hexadecyl-N-methylpiperidinium bromide (C16MDB) with the anionic surfactant sodium laurate (SL) in aqueous solutions were investigated using rheological measurements. The effects of sodium laurate and temperature on the worm-like micelles and the mechanism of the observed shear thinning phenomenon and pseudoplastic behavior were systematically investigated. Additionally, cryogenic transmission electron microscopy images further ascertained existence of entangled worm-like micelles. PMID:25296131

Yan, Zhihu; Dai, Caili; Feng, Haishun; Liu, Yifei; Wang, Shilu

2014-01-01

375

Lung surfactant and pulmonary toxicology  

Microsoft Academic Search

Pulmonary surfactant is essential for a proper functioning of the mammalian lung. It provides mechanical stability to the\\u000a alveoli, prevents alveolar edema, and plays a role in the pulmonary defense system. Because of this vital role, alterations\\u000a in the surfactant system may account for some of the observed toxic effects of environmental agents and drugs on the lung.\\u000a In this

Henk P. Haagsman; Lambert M. G. van Golde

1985-01-01

376

A STUDY OF SILICONE OIL-IN-WATER EMULSIONS  

Microsoft Academic Search

Emulsions of silicone oil-in water were formed using a Brinkmann Polytron homogenizer with Igepal CO-530 as an emulsifier. Silicone viscosities ranged from 10 to 33,000 mPa.s at 25°C. Rheological characteristics and particle size analyses of silicone oil-in-water emulsions were studied. At high volume fraction of the dispersed phase (70%-75%), silicone oil-in-water emulsions were stable. At lower volume fractions (50%-60%), emulsions

BRAM A. SAADEVANDI; JACQUES L. ZAKIN

1997-01-01

377

A lipid emulsion reduces mortality from clomipramine overdose in rats.  

PubMed

Tricyclic antidepressants are a common cause of self poisoning. Since these drugs are highly lipid soluble, we examined the interaction between imipramine and a lipid emulsion. Rats were given an iv dose of imipramine with either normal saline or a lipid emulsion as vehicle. The rats who received the lipid emulsion had a significantly lower mortality. The role of lipid emulsions poisoning therapy is reviewed. PMID:11824772

Yoav, Goor; Odelia, Goor; Shaltiel, Cabilil; Goor, Yoav; Goor, Odelia; Cabili, Shaltiel

2002-02-01

378

Colloidal stability of hydrophobic nanoparticles in ionic surfactant solutions: definition of the critical dispersion concentration.  

PubMed

The dispersion stability diagrams of hydrophobic boehmite nanoparticles in aqueous n-alkyltrimethylammonium bromide solutions (alkyl chain lengths 10-16) were studied over a wide range of particle and surfactant concentrations. The surfactant molecules adsorb tail-on on the particle surface, which provides the colloidal stability through electrostatic repulsion. In the stable region of each diagram, bimodal particle size distributions (50 and 500 nm) are found at lower surfactant concentration, which give way to monomodal distributions (50 nm) at higher concentration. This deagglomeration is connected with the cmc of the surfactants and can be explained by a desorption of counterions from the self-assembled surfactant layer. The desorption is caused by changes in the counterion concentration upon micellization. At low particle concentrations, the transition from the intermediate to the stable region, that is, the disappearance of the precipitate, occurs at a constant surfactant concentration. This concentration is introduced as the "critical dispersion concentration" (cdc), this being the lowest required concentration of a surfactant that is necessary to disperse the hydrophobic particles. The logarithm of the cdc shows a linear dependence on the surfactant chain length, thus a cmc-analogous behavior. The ratio cdc/cmc decreases with increasing surfactant chain length, indicating that long-chain surfactants are more efficient in dispersing nanoparticles than are their lower homologues. The existence of a system-specific critical cdc/cmc ratio, beyond which stable dispersions cannot be obtained, is proposed, which explains the disability of short-chain surfactants to disperse colloids. PMID:19146423

Dederichs, Thomas; Möller, Martin; Weichold, Oliver

2009-02-17

379

Development of surfactant coacervation in aqueous solution.  

PubMed

Coacervation is a phenomenon in which a colloidal dispersion separates into two immiscible liquid phases: a liquid rich in colloidal phase in equilibrium with another diluted liquid phase. Surfactant coacervation here refers to coacervation whose main components are surfactants with low molecular weights. Over the past two decades, surfactants have been greatly developed and studies on coacervation in systems of novel surfactants have been reported. This review summarizes the development of coacervation occurring in monomeric surfactants, one-head and two-tail surfactants, gemini surfactants and their mixtures. The effects of surfactant molecular structure and external conditions on critical conditions for coacervation, structures of precursors and coacervates, and their relationships are described. The effects of inorganic salts, alcohols and organic salts on surfactant coacervation are also reviewed. PMID:25144160

Wang, Meina; Wang, Yilin

2014-09-24

380

Extraction of oil from stable oil-water emulsions  

Microsoft Academic Search

This patent describes a process of extracting oil from oil-water emulsions containing suspended solid particulates comprising the steps of: (A) introducing the emulsion into a vessel, (B) pressurizing the vessel by adding a volatile hydrocarbon whereby the volatile hydrocarbon in the vessel is in the liquefied state and forms a two-phase system with the emulsion, (C) maintaining the pressure for

S. C. Paspek; C. P. Eppig

1989-01-01

381

Tweens demulsification effects on heavy crude oil\\/water emulsion  

Microsoft Academic Search

The demulsification role of Tweens (nonionic polymers) was determined in the separation of water from heavy crude oil emulsion. According to the previous researches, these nonionic polymers, having hydrophilic and lipophilic groups, are appropriate for making oil in water emulsion. In this research their effects in certain concentrations on demulsifying of water in crude oil emulsion were proved. High molecular

Esmaiel Soleimani; Nastaran Hayati Roodbari; Alireza Badiei; Yeganeh Khaniani

382

Extraction of oil from stable oil-water emulsions  

Microsoft Academic Search

This patent describes a process of extracting oil from oil-water emulsions containing suspended solid particulates comprising the steps of: (A) introducing the emulsion into a vessel, (B) pressurizing the vessel by adding a volatile hydrocarbon whereby the volatile hydrocarbon in the vessel is in the liquefied state and forms a two-phase system with the emulsion, (C) maintaining the pressure for

S. C. Paspek; C. P. Eppig

1988-01-01

383

Extraction of oil from stable oil-water emulsions  

Microsoft Academic Search

This patent describes a process of extracting oil from oil-water emulsions containing suspended solid particulates. It comprises introducing the emulsion into vessel in an extraction system, pressurizing the vessel with a volatile hydrocarbon whereby the volatile hydrocarbon is in the liquified state and forms a two-phase system with the emulsion, maintaining the pressure for a period of time sufficient to

S. C. Paspek; C. P. Eppig

1991-01-01

384

Creaming Rate of Amyl Alcohol?in?Water Emulsions  

Microsoft Academic Search

Amyl alcohol\\/water emulsion forms during dye removal from aqueous phases by solvent (amyl alcohol) extraction using reverse micelles of sodium dodecyl benzene sulphonate (SDBS). The phase separation time of the emulsion dictates the residence of the dye removal processes by reverse micelles. The creaming rate of amyl alcohol\\/water emulsion formed in the presence of SDBS has been studied and the

S. Basu; A. Kandhari; A. S. Negi

2005-01-01

385

Automated track recognition and event reconstruction in nuclear emulsion  

Microsoft Academic Search

The major advantages of nuclear emulsion for detecting charged particles are its submicron position resolution and sensitivity to minimum ionizing particles. These must be balanced, however, against the difficult manual microscope measurement by skilled observers required for the analysis. We have developed an automated system to acquire and analyze the microscope images from emulsion chambers. Each emulsion plate is analyzed

P. Deines-Jones; A. Aranas; M. L. Cherry; J. Dugas; D. Kudzia; B. S. Nilsen; K. Sengupta; C. J. Waddington; J. P. Wefel; B. Wilczynska; H. Wilczynski; B. Wosiek

1997-01-01

386

Perfluorocarbon emulsions prevent hypoxia of pancreatic ?-cells.  

PubMed

As oxygen carriers, perfluorocarbon emulsions might be useful to decrease hypoxia of pancreatic islets before transplantation. However, their hydrophobicity prevents their homogenisation in culture medium. To increase the surface of contact between islets and Perfluorooctyl bromide (PFOB), and consequently oxygen delivery, we tested effect of a PFOB emulsion in culture medium on ?-cell lines and rat pancreatic islets. RINm5F ?-cell line or pancreatic rat islets were incubated for 3 days in the presence of PFOB emulsion in media (3.5% w/v). Preoxygenation of the medium was performed before culture. Cell viability was assessed by apoptotic markers (Bax and Bcl-2) and by staining (fluoresceine diacetate and propidium iodide). ?-Cell functionality was determined by insulin release during a glucose stimulation test and. Hypoxia markers, HIF-1? and VEGF, were studied at days 1 and 3 using RT-PCR, Western blotting, and ELISA. PFOB emulsions preserved viability and functionality of RINm5F cells with a decrease of HIF-1? and VEGF expression. Islets viability was preserved during 3 days of culture. Secretion of VEGF was higher in untreated control (0.09 ± 0.041 ?g VEGF/mg total protein) than in PFOB emulsion incubated islets (0.02 ± 0.19 ?g VEGF/mg total protein, n = 4, p < 0.05) at day 1. At day 3, VEGF secretion was increased as compared to day 1 in control (0.23 ± 0.04 ?g VEGF/mg total protein) but it was imbalance by the presence of PFOB emulsion (0.09 ± 0.03 ?g VEGF/mg total protein, n = 5, p < 0.05). While insulin secretion was maintained in response to a glucose stimulation test until day 3 when islets were incubated in the presence of PFOB emulsion preoxygenated (0.81 ± 0.16 at day 1 vs. 0.75 ± 0.24 at day 3), the ability to secrete insulin in the presence of high glucose concentration was lost in islets controls (0.51 ± 0.18 at day 1 vs. 0.21 ± 0.13 at day 3). Atmospheric oxygen delivery by PFOB emulsion might be sufficient to decrease islets hypoxia. However, to improve islets functionality, overoxygenation is needed. Finally, maintenance of islet viability and functionality for several days after isolation could improve the outcome of islets transplantation. PMID:21944582

Maillard, E; Juszczak, M T; Langlois, A; Kleiss, C; Sencier, M C; Bietiger, W; Sanchez-Dominguez, M; Krafft, M P; Johnson, P R V; Pinget, M; Sigrist, S

2012-01-01

387

Effect of anionic surfactants on grafting density of gelatin modified with PDMS-E.  

PubMed

The effect of anionic surfactants on the interfacial compatibility in mono epoxy terminated polydimethylsiloxane (PDMS-E) macromonomer and gelatin mixed system was studied by Gibbs free energy (?GM), which played a crucial role in deciding the grafting density of immiscible polymer in heterogeneous system. Aggregation behavior of gelatin chains at boundary between gelatin phase and solvent phase was investigated using viscosity, surface tension and conductivity measurements. Viscosity analysis showed a regular increase in viscosity with the increasing alkyl chain length from C7 to C16 of the homologous alkyl sulfate surfactants. Changes of surface tension exhibited the regular curves of polyelectrolyte-anionic surfactant for alkyl sulfate surfactant systems. The results demonstrated that aggregate structure of gelatin-sulfate surfactants was dominated by electrostatic and hydrophobic interactions, which resulted in a self-assembly process of the hydrophobic segments and hydrophilic segments among gelatin chains and surfactant molecules. However, the interactions between gelatin and alkyl sulfonate surfactants were mainly governed by hydrophobic interactions, which induced conformation change of gelatin molecules. Well-ordered arrangement of gelatin chains at a fluid interface has observed by high-resolution transmission electron microscopy (HR-TEM). It is a key factor to contribute to the reduction of interfacial free energy, which mainly depends on the hydrophobic interaction between gelatin and alkyl sulfate/sulfonate surfactants. MD simulations conclusions are great agreement with our experimental results. PMID:24216622

Xu, Jing; Xu, Zhen; Qiao, Cong-De; Li, Tian-Duo

2014-02-01

388

Development of cost-effective surfactant flooding technology. Quarterly report, April 1995--June 1995  

SciTech Connect

The objective of this research is to develop cost-effective surfactant flooding technology by using surfactant simulation studies to evaluate and optimize alternative design strategies taking into account reservoir characteristics, process chemistry, and process design options such as horizontal wells. Task 1 is the development of an improved numerical method for our simulator that will enable us to solve a wider class of these difficult simulation problems, accurately and affordably. Task 2 is the application of this simulator to the optimization of surfactant flooding to reduce its risk and cost. The objective of Task 2 is to investigate and evaluate, through a systematic simulation study, surfactant flooding processes that are cost-effective. We previously have reported on low tension polymer flooding as an alternative to classical surfactant/polymer flooding. In this reporting period, we have studied the potential of improving the efficiency of surfactant/polymer flooding by coinjecting an alkali agent such as sodium carbonate under realistic reservoir conditions and process behavior. The alkaline/surfactant/polymer (ASP) flood attempts to take advantage of high pH fluids to reduce the amount of surfactant needed by the chemical reactions between injection fluid and formation fluid or formation rocks.

Pope, G.A.; Sepehrnoori, K.; Jessen, F.W.

1995-12-31

389

Adsorption of protein-surfactant complexes at the water/oil interface.  

PubMed

Interfacial tension measurements have been performed at the water/hexane interface on mixtures of the bovine milk protein ?-lactoglobulin and positively charged cationic surfactants (alkytrimethylammonium bromides). The addition of surfactants with different chain lengths leads to the formation of protein-surfactant complexes with different adsorption properties as compared to those of the single protein. In this study, the formation of complexes has been observed clearly for protein-long chain surfactant (TTAB and CTAB) mixtures, which has shown in addition to specific electrostatic interactions the relevance of hydrophobic interactions between surfactant molecules and the protein. The modeling of interfacial tension data by using a mixed adsorption model provides a quantitative understanding of the mixture behavior. Indeed, the value of the adsorption constant of the protein obtained in the presence of surfactants has strongly varied as compared to the single protein. Actually, this parameter which represents the affinity of the molecule for the interface is representative of the hydrophobic character of the compound and so of its surface activity. Even if a more hydrophobic and more surface active protein-surfactant complex has been formed, the replacement of this complex from the interface by surfactants close to their cmc was observed. PMID:21188992

Pradines, Vincent; Fainerman, Valentin B; Aksenenko, Eugene V; Krägel, Jürgen; Wüstneck, Rainer; Miller, Reinhard

2011-02-01

390

Mode changes associated with oil droplet movement in solutions of gemini cationic surfactants.  

PubMed

Micrometer-sized self-propelled oil droplets in nonequilibrium systems have attracted much attention, since they form stable emulsions composed of oil, water, and surfactant which represent a primitive type of inanimate chemical machinery. In this work, we examined means of controlling the movement of oil droplets by studying the dynamics of n-heptyloxybenzaldehyde droplets in phosphate buffers containing alkanediyl-?,?-bis(N-dodecyl-N,N-dimethylammonium bromide) (nG12) with either tetramethylene (4G12), octaethylene (8G12), or dodecamethylene (12G12) chains in the linker moiety. Significant differences in droplet dynamics were observed to be induced by changes in the linker structure of these gemini cationic surfactants. In a phosphate buffer containing 30 mM 4G12, self-propelled motion of droplets concurrent with the formation of molecular aggregates on their surfaces was observed, whereas the fusion of oil droplets was evident in both 8G12 and 12G12 solutions. We also determined that the surface activities and the extent of molecular self-assembly of the surfactants in phosphate buffer were strongly influenced by the alkyl chain length in the linker moiety. We therefore conclude that the surface activities of the gemini cationic surfactant have important effects on the oil-water interfacial tension of oil droplets and the formation of molecular aggregates and that both of these factors induce the unique movement of the droplets. PMID:23706080

Banno, Taisuke; Miura, Shingo; Kuroha, Rie; Toyota, Taro

2013-06-25

391

Lipoplexes formed from sugar-based gemini surfactants undergo a lamellar-to-micellar phase transition at acidic pH. Evidence for a non-inverted membrane-destabilizing hexagonal phase of lipoplexes  

Microsoft Academic Search

The present study aims at a better understanding of the mechanism of transfection mediated by two sugar-based gemini surfactants GS1 and GS2. Previously, these gemini surfactants have been shown to be efficient gene vectors for transfection both in vitro and in vivo. Here, using Nile Red, a solvatochromic fluorescent probe, we investigated the phase behavior of these gemini surfactants in

Luc Wasungu; Marc C. A. Stuart; Marco Scarzello; Jan B. F. N. Engberts; Dick Hoekstra

2006-01-01

392

Phase diagrams of stoichiometric polyelectrolyte-surfactant complexes  

NASA Astrophysics Data System (ADS)

When a water-soluble polyelectrolyte is combined with an oppositely-charged surfactant solution at a stoichiometric charge ratio, self-assembly into a highly ordered, water-insoluble complex can occur. These materials exhibit phase structures which are analogous to their pure surfactant components, and significant effort has been made in the past several decades to characterize, predict, and control the various morphologies observed in these systems. However, a truly comprehensive understanding of the phase behavior of these systems is lacking. The purpose of this project is to establish general phase diagrams for self-assembled, stoichiometric poly(acrylate-co-acrylamide)-cetyltrimethylammonium halide (PAAm-CTAX) complexes by studying phase structure as a function of ionic strength, salt type, polyelectrolyte charge density, temperature, and applied osmotic pressure with small-angle X-ray scattering (SAXS). By developing a deeper understanding of the phase behavior and energetics of such a model system, it is hoped that general trends can be extrapolated to other polyelectrolyte-surfactant systems, such as polysaccharide-surfactant systems, which may provide the means to template desired structures in nanoporous, biocompatible matrices. Materials such as these may be attractive targets for drug delivery and nanoscale separation applications.

Leonard, Michael J.

393

Electrical properties of chain microstructure magnetic emulsions in magnetic field  

E-print Network

The work deals with the experimental study of the emulsion whose dispersion medium is a magnetic fluid while the disperse phase is formed by a glycerin-water mixture. It is demonstrated that under effect of a magnetic field chain aggregates form from the disperse phase drops. Such emulsion microstructure change affects its macroscopic properties. The emulsion dielectric permeability and specific electrical conductivity have been measured. It is demonstrated that under the effect of relatively weak external magnetic fields (~ 1 kA/m) the emulsion electrical parameters may change several fold. The work theoretically analyzes the discovered regularities of the emulsion electrical properties.

Arthur Zakinyan; Yuri Dikansky; Marita Bedzhanyan

2014-02-05

394

Nanoparticle silica-stabilised oil-in-water emulsions: improving emulsion stability  

Microsoft Academic Search

The rapid phase separation of oil-in-water (o\\/w) emulsions prepared from non-polar oil and alkaline dispersions of hydrophilic silica nanoparticles alone is described. A study of the roles of the surface chemistry of the particles and the type and composition of the oil and aqueous phases in improving the stability of these emulsions is then reported. Alteration of the particle charge

Bernard P. Binks; Catherine P. Whitby

2005-01-01

395

Removal of chromium from aqueous waste solution using liquid emulsion membrane.  

PubMed

This paper presents a comprehensive study in recovery of Cr (VI) from dilute HCl solution using liquid emulsion membrane (LEM). The liquid membrane is made up of Tri-octylphosphine oxide (TOPO) as a carrier, cyclohexane as an organic diluent, sodium hydroxide as a stripping solution and Span-80 (sorbitain monooleate) as an emulsifying agent. The selection of the extractant (TOPO) and the stripper (NaOH) was chosen on the basis of conventional liquid-liquid extraction studies. The important parameters affecting the permeation of Cr (VI) through the prepared membrane are hydrogen ion concentration in the external aqueous phase, stirring speed of mixing the two phases, type of diluents, carrier concentration, stripper concentration, membrane to feed ratio and volume fraction were systematically investigated. The effect of surfactant types and concentration on the stability of LEM were studied because of its important role in the permeation process. PMID:19372004

Hasan, M A; Selim, Y T; Mohamed, K M

2009-09-15

396

Towards a consistent mechanism of emulsion polymerization-new experimental details.  

PubMed

The application of atypical experimental methods such as conductivity measurements, optical microscopy, and nonstirred polymerizations to investigations of the 'classical' batch ab initio emulsion polymerization of styrene revealed astonishing facts. The most important result is the discovery of spontaneous emulsification leading to monomer droplets even in the quiescent styrene in water system. These monomer droplets with a size between a few and some hundreds of nanometers, which are formed by spontaneous emulsification as soon as styrene and water are brought into contact, have a strong influence on the particle nucleation, the particle morphology, and the swelling of the particles. Experimental results confirm that micelles of low-molecular-weight surfactants are not a major locus of particle nucleation. Brownian dynamics simulations show that the capture of matter by the particles strongly depends on the polymer volume fraction and the size of the captured species (primary free radicals, oligomers, single monomer molecules, or clusters). PMID:19816526

Tauer, Klaus; Hernandez, Hugo; Kozempel, Steffen; Lazareva, Olga; Nazaran, Pantea

2008-05-01

397

Na-caseinate/oil/water systems: emulsion morphology diagrams.  

PubMed

The concentrated (dispersed phase 50-70 wt%) composition space of Na-caseinate, a family of milk proteins, stabilised emulsions was investigated for three different oils: soybean oil, palm olein and tetradecane with pH 6.8 phosphate buffer continuous phase. The variation of emulsion stability and microstructure were explored using static light scattering, diffusion nuclear magnetic resonance, cryo-scanning electron microscopy, rheology and the time varying macroscopic phase separation of the emulsions. For soybean oil and palm olein a rich diversity of emulsion microstructures and stabilities are realised. Five emulsion domains, each having a different microstructure and macroscopic stability have been identified within the composition space probed. For the lowest concentrations of emulsifier bridging flocculation is evident and emulsions are of low stability. Increasing Na-caseinate concentration leads to an increased stability and the existence of distinct individual oil droplets, visualised using cryo-scanning electron microscopy. Further increases in Na-caseinate concentration reduce emulsion stability due to depletion flocculation. Na-caseinate self-assembly is then initiated. At sufficiently high Na-caseinate and/or oil concentrations the continuous phase of the emulsion is a three-dimensional protein network and emulsion stability is again enhanced. At the limits of the emulsion composition space a gel-like paste is formed. The diversity of emulsion microstructure is reduced when tetradecane is the discrete phase. Na-caseinate self-assembly is limited and there is no evidence for formation of a protein network. PMID:22709624

Tan, Hui Lin; McGrath, Kathryn M

2012-09-01

398

Mixed Micellization of Dimeric (Gemini) Surfactants and Conventional Surfactants  

Microsoft Academic Search

The aqueous solutions of mixtures of various conventional surfactants and dimeric anionic and cationic surfactants have been investigated by electrical conductivity, spectrofluorometry, and time-resolved fluorescence quenching to determine the critical micelle concentrations and the micelle aggregation numbers in these mixtures. The following systems have been investigated: 12-2-12\\/DTAB, 12-2-12\\/C12E6, 12-2-12\\/C12E8, 12-3-12\\/C12E8, Dim3\\/C12E8, and Dim4\\/C12E8 (12-2-12 and 12-3-12=dimethylene-1,2- and trimethylene-1,3-bis(dodecyldimethylammonium bromide), respectively;

R. G. Alargova; I. I. Kochijashky; M. L. Sierra; K. Kwetkat; R. Zana

2001-01-01

399

Protein-based pickering emulsion and oil gel prepared by complexes of zein colloidal particles and stearate.  

PubMed

This paper describes the successful preparation of a protein-based Pickering emulsion, with superior stability against both coalesence and creaming, through a novel strategy of facilitating the formation of protein particles and small molecular weight surfactant complexes; these complexes are able to overcome multiple challenges including limited solubility, poor diffusive mobility, and low interfacial loading. Soluble complexes of water-insoluble corn protein, zein colloidal particles, and surfactant sodium stearate (SS) were fabricated by simple ultrasonication. Gel trapping technology combined with SEM was applied to characterize the adsorbed particles monolayer at the oil-water interface; results revealed an enhanced adsorption and targeted accumulation of zein particles at the interface with the increase of SS concentration. Partial unfolding of zein particles modified by SS above its critical complexation concentration triggered the aggregation and close packing of particles at the oil-water interface and endowed a steric barrier against the coalescence of oil droplets. Moreover, protein-based oil gels without oil leakage were obtained by one-step freeze-drying of the zein-stabilized Pickering emulsions, which could be developed to a viable strategy for structuring liquid oils into semisolid fats without the use of saturated or trans fats. PMID:24621373

Gao, Zhi-Ming; Yang, Xiao-Quan; Wu, Na-Na; Wang, Li-Juan; Wang, Jin-Mei; Guo, Jian; Yin, Shou-Wei

2014-03-26

400

Improved physical stability and injectability of non-aqueous in situ PLGA microparticle forming emulsions.  

PubMed

The goal of this study was to obtain physically stable non-aqueous in situ forming microparticle (ISM) emulsions capable of forming biodegradable microparticles upon injection. ISM emulsions consist of a biocompatible organic PLGA solution dispersed in a continuous oil phase prepared in a two-syringe/connector system prior to administration. A variety of parenteral approved excipients were tested for a stability-enhancing effect and possible stabilization mechanisms evaluated. Glycerol monostearate (GMS) showed superior stabilizing potential prolonging the emulsion stability from a few minutes to more than 12h. Flow behavior analysis, differential scanning calorimetry, polarized light- and Cryo-electron microscopy revealed, that the stabilization was caused by an immediate, more than 5-fold viscosity increase in the continuous phase after emulsification and by a stabilized interface through a liquid crystalline GMS layer around the polymer solution droplets. Despite the viscosity increase the injectability of the stabilized ISM emulsion was improved by about 30% compared to the corresponding highly viscous PLGA solution (in situ implant) due to a pronounced shear thinning of the GMS containing oil phase. The injectability improvement allows a faster administration or enables the use of thinner needles and hence reduced patient discomfort. PMID:22677417

Voigt, M; Koerber, M; Bodmeier, R

2012-09-15