The effect of pressure on the phase behavior of surfactant systems: An experimental study

DEFF Research Database (Denmark)

Sandersen, Sara Bülow; Stenby, Erling Halfdan; von Solms, Nicolas

2012-01-01

Enhanced oil recovery is employed in many mature oil reservoirs to maintain or increase the reservoir recovery factor. In this context, surfactant flooding has recently gained interest again. Surfactant flooding is the injection of surfactants (and co-surfactants) into the reservoir, in order...... to create microemulsions at the interface between crude oil and water, thus obtaining very low interfacial tension, which consequently helps mobilize the trapped oil.In this work a surfactant system, which has been thoroughly described at atmospheric pressure, is examined at elevated pressure. The effect...

Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

International Nuclear Information System (INIS)

Voisin, David

2002-01-01

cationically modified guar gums (of varying charge density) with two anionic surfactants: sodium lauryl (or dodecyl) ether sulfate [SLES] and sodium dodecyl sulfate [SDS], for various concentrations of the polyelectrolyte and added sodium chloride, at room temperature. The addition of sodium chloride has only a minor net effect on the CFC, but increases the CSC significantly. The interactions between the cationic polyelectrolyte and the surfactant have been studied in the one-phase regions, i.e. below the CFC and above the CSC, using different techniques. Surface tension, electrophoresis, light scattering and viscosimetry have been employed. In the two-phase region, the sedimented floe phase has been analysed and the flocculation has been investigated. Rheology of the floe phase has been studied, after a mild compression by centrifugation. The initial rate of flocculation has been determined, using stop-flow equipment. The growth and the structure of the flocs have been investigated by light scattering. The open-network flocs of polyelectrolyte-surfactant particles grow to ∼10's μm in size, prior to their eventual settling out. Other colloidal particles can be trapped within these large flocs, and the flocs can be used to transport these particles to a macroscopic surface. The deposition and the removal of such composite flocs on glass surfaces, under flow, have been studied using a flow cell device coupled with an optical microscope. Scanning electron microscopy and atomic force microscopy have also been employed. (author)

Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

Energy Technology Data Exchange (ETDEWEB)

Voisin, David

2002-07-01

the CSC have been determined for mixtures of cationically modified guar gums (of varying charge density) with two anionic surfactants: sodium lauryl (or dodecyl) ether sulfate [SLES] and sodium dodecyl sulfate [SDS], for various concentrations of the polyelectrolyte and added sodium chloride, at room temperature. The addition of sodium chloride has only a minor net effect on the CFC, but increases the CSC significantly. The interactions between the cationic polyelectrolyte and the surfactant have been studied in the one-phase regions, i.e. below the CFC and above the CSC, using different techniques. Surface tension, electrophoresis, light scattering and viscosimetry have been employed. In the two-phase region, the sedimented floe phase has been analysed and the flocculation has been investigated. Rheology of the floe phase has been studied, after a mild compression by centrifugation. The initial rate of flocculation has been determined, using stop-flow equipment. The growth and the structure of the flocs have been investigated by light scattering. The open-network flocs of polyelectrolyte-surfactant particles grow to {approx}10's {mu}m in size, prior to their eventual settling out. Other colloidal particles can be trapped within these large flocs, and the flocs can be used to transport these particles to a macroscopic surface. The deposition and the removal of such composite flocs on glass surfaces, under flow, have been studied using a flow cell device coupled with an optical microscope. Scanning electron microscopy and atomic force microscopy have also been employed. (author)

Single well surfactant test to evaluate surfactant floods using multi tracer method

Science.gov (United States)

Sheely, Clyde Q.

1979-01-01

Data useful for evaluating the effectiveness of or designing an enhanced recovery process said process involving mobilizing and moving hydrocarbons through a hydrocarbon bearing subterranean formation from an injection well to a production well by injecting a mobilizing fluid into the injection well, comprising (a) determining hydrocarbon saturation in a volume in the formation near a well bore penetrating formation, (b) injecting sufficient mobilizing fluid to mobilize and move hydrocarbons from a volume in the formation near the well bore, and (c) determining the hydrocarbon saturation in a volume including at least a part of the volume of (b) by an improved single well surfactant method comprising injecting 2 or more slugs of water containing the primary tracer separated by water slugs containing no primary tracer. Alternatively, the plurality of ester tracers can be injected in a single slug said tracers penetrating varying distances into the formation wherein the esters have different partition coefficients and essentially equal reaction times. The single well tracer method employed is disclosed in U.S. Pat. No. 3,623,842. This method designated the single well surfactant test (SWST) is useful for evaluating the effect of surfactant floods, polymer floods, carbon dioxide floods, micellar floods, caustic floods and the like in subterranean formations in much less time and at much reduced cost compared to conventional multiwell pilot tests.

Flavonoid-surfactant interactions: A detailed physicochemical study

Science.gov (United States)

Singh, Onkar; Kaur, Rajwinder; Mahajan, Rakesh Kumar

2017-01-01

The aim of this article is to study the interactions between flavonoids and surfactants with attention of finding the probable location of flavonoids in micellar media that can be used for controlling their antioxidant behavior. In present study, the micellar and interfacial behavior of twin tailed anionic surfactants viz. sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium bis(2-ethylhexyl)phosphate (NaDEHP) in the presence of two flavonoids, namely quercetin (QUE) and kaempferol (KFL) have been studied by surface tension measurements. UV-visible, fluorescence and differential pulse voltammetric (DPV) measurements have been employed to predict the probable location of flavonoids (QUE/KFL) within surfactant (AOT/NaDEHP) aggregates. Dynamic light scattering (DLS) measurements further confirmed the solubilization of QUE/KFL in AOT/NaDEHP aggregates deduced from increased hydrodynamic diameter (Dh) of aggregates in the presence of flavonoids. Both radical scavenging activity (RSA) and degradation rate constant (k) of flavonoids are found to be higher in NaDEHP micelles as compared to AOT micelles.

Defluorination of drinking water using surfactant modified zeolites ...

African Journals Online (AJOL)

This study focused on the removal of fluoridefrom groundwater by employing surfactant modified zeolites (SMZ) synthesized using locallyavailable kaolin material as precursor. The zeolite synthesis involved calcination of kaolin, alkaline fusion and hydrothermal treatment. The final product was modified with 5g/L ...

Ecotoxicological characterization of polyoxyethylene glycerol ester non-ionic surfactants and their mixtures with anionic and non-ionic surfactants.

Science.gov (United States)

Ríos, Francisco; Fernández-Arteaga, Alejandro; Lechuga, Manuela; Fernández-Serrano, Mercedes

2017-04-01

This paper reports on a study that investigated the aquatic toxicity of new non-ionic surfactants derived from renewable raw materials, polyoxyethylene glycerol ester (PGE), and their binary mixtures with anionic and non-ionic surfactants. Toxicity of pure PGEs was determined using representative organisms from different trophic levels: luminescent bacteria (Vibrio fischeri), microalgae (Pseudokirchneriella subcapitata), and freshwater crustaceans (Daphnia magna). Relationships between toxicity and the structural parameters such as unit of ethylene oxide (EO) and hydrophilic-lipophilic balance (HLB) were evaluated. Critical micellar concentration (CMC) in the conditions of the toxicity test was also determined. It was found that the toxicity of the aqueous solutions of PGE decreased when the number of EO units in the molecule, HLB, and CMC increased. PGEs showed lower CMC in marine medium, and the toxicity to V. ficheri is lower when the CMC was higher. Given their non-polar nature, narcosis was expected to be the primary mode of toxic action of PGEs. For the mixture of surfactants, we observed that the mixtures with PGE that had the higher numbers of EO units were more toxic than the aqueous solutions of pure surfactants. Moreover, we found that concentration addition was the type of action more likely to occur for mixtures of PGE with lower numbers of EO units with non-ionic surfactants (alkylpolyglucoside and fatty alcohol ethoxylate), whereas for the mixture of PGE with lower EO units and anionic surfactant (ether carboxylic derivative), the most common response type was response addition. In case of mixtures involving amphoteric surfactants and PGEs with the higher numbers of EO units, no clear pattern with regard to the mixture toxicity response type could be observed.

Comprehensive study of tartrazine/cationic surfactant interaction.

Science.gov (United States)

Shahir, Afshin Asadzadeh; Javadian, Soheila; Razavizadeh, Bi Bi Marzieh; Gharibi, Hussein

2011-12-15

Interaction of a food dye, tartrazine, with some cationic conventional and gemini surfactants, tetradecyltrimethylammonium bromide (TTAB), N,N'-ditetradecyl-N,N,N',N'-tetramethyl-N,N'-butanediyl-diammonium dibromide (14,4,14), and N,N'-didodecyl-N,N,N',N'-tetramethyl-N,N'-butanediyl-diammonium dibromide (12,4,12), were first investigated comprehensively employing conductometry, tensiometry, and UV-visible spectroscopy. Tartrazine was found to behave in the same manner as aromatic counterions. The formation of ion pairs reflected as a considerable increase of the surfactant efficiency in tensiometry plots and their stoichiometry were determined by Job's method of continuous variations. For the tartrazine/TTAB system, nonionic DS(3), ionic DS(2-), and/or DS(2)(-) ion pairs, their small premicelles, and tartrazine-rich micelles were constituted as well as dye-containing TTAB-rich micelles. Insoluble J-aggregates of DS(-) ion pairs and cylindrical surfactant-rich micelles were also formed in tartrazine/gemini surfactant systems and recognized by transmission electron microscopy. The zeta potential and the size of the aggregates were determined using dynamic light scattering and confirmed the suggested models for the processes happening in each system. Cyclic voltammetry was applied successfully to track all of these species using tartrazine's own reduction peak current for the first time.

Surfactant phosphatidylcholine metabolism and surfactant function in preterm, ventilated lambs

International Nuclear Information System (INIS)

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

1989-01-01

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

Persurf, a new method to improve surfactant delivery: a study in surfactant depleted rats.

Directory of Open Access Journals (Sweden)

Wolfram Burkhardt

Full Text Available 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.

The toxicity of cationic surfactant HDTMA-Br, desorbed from surfactant modified zeolite, towards faecal indicator and environmental microorganisms.

Science.gov (United States)

Reeve, Peter J; Fallowfield, Howard J

2017-10-05

Surfactant Modified Zeolite (SMZ) represents a versatile, cost-effective permeable reactive material, capable of treating multiple classes of contaminants. The potential for HDTMA-Br, a cationic surfactant commonly used to modify zeolite, to desorb from the zeolite surface has been identified as a potential issue for the ongoing use of SMZ in water remediation contexts. This paper investigates the toxicity of HDTMA-Br towards enteric virus surrogates, F-RNA bacteriophage MS2 and E. coli, Bacillus subtilis, and soil microflora. The concentration of surfactant desorbing from SMZ was quantified through a bioassay using E. coli. Results showed HDTMA-Br concentrations of ≥10 -5 M were toxic to MS2, ≥10 -4 M were toxic to E. coli and ≥10 -6 M were toxic to B. subtilis. No toxic relationship was established between HDTMA-Br and soil microflora. Desorption of ≥10 -4 M of HDTMA-Br was shown for the two SMZ samples under the mixing conditions used. Effects of this surfactant on total soil microflora were ambiguous since no toxic relationship could be established, however, HDTMA-Br, at concentrations desorbing from SMZ, were shown to impact the soil bacterium B. subtilis. Further research is required to determine the effect of this surfactant on microbial populations and species diversity in soils. Copyright © 2017 Elsevier B.V. All rights reserved.

Nonlinear dynamics in experimental devices with compressed/expanded surfactant monolayers

International Nuclear Information System (INIS)

Higuera, M; Perales, J M; Vega, J M

2014-01-01

A theory is provided for a common experimental set up that is used to measure surface properties in surfactant monolayers. The set up consists of a surfactant monolayer (over a shallow liquid layer) that is compressed/expanded in a periodic fashion by moving in counter-phase two parallel, slightly immersed solid barriers, which vary the free surface area and thus the surfactant concentration. The simplest theory ignores the fluid dynamics in the bulk fluid, assuming spatially uniform surfactant concentration, which requires quite small forcing frequencies and provides reversible dynamics in the compression/expansion cycles. In this paper, we present a long-wave theory for not so slow oscillations that assumes local equilibrium but takes the fluid dynamics into account. This simple theory uncovers the physical mechanisms involved in the surfactant behavior and allows for extracting more information from each experimental run. The conclusion is that the fluid dynamics cannot be ignored, and that some irreversible dynamics could well have a fluid dynamic origin. (paper)

Thermodynamic aspects of polymer–surfactant interactions: Gemini (16-5-16-PVP-water system

Directory of Open Access Journals (Sweden)

Naved Azum

2016-11-01

Full Text Available The interaction between polyvinylpyrrolidone (PVP and gemini surfactant (16-5-16 in aqueous solution has been analyzed using conductometry. From conductivity data the critical aggregation concentration (cac, critical micelle concentration (cmc, the effective degree of counter-ion binding (β at different temperatures were obtained. The thermodynamic parameters, i.e., Gibbs energy of aggregation and micellization, standard enthalpy of aggregation, and standard entropy of aggregation of surfactant/polymer system were estimated, employing pseudophase separation model. The negative values of Gibbs energy and standard enthalpy suggest that the surfactant/polymer aggregation process is spontaneous and exothermic respectively.

The effect of surfactant on pollutant biosorption of Trametes versicolor

Science.gov (United States)

Gül, Ülküye Dudu; Silah, Hülya; Akbaş, Halide; Has, Merve

2016-04-01

The major problem concerning industrial wastewater is treatment of dye and heavy metal containing effluents. Industrial effluents are also contained surfactants that are used as levelling, dispersing and wetting agents. The purpose of this study was to investigate the effect of surfactant on textile dye biosorption properties of a white rot fungus named Trametes versicolor. Reactive dyes are commonly used in textile industry because of their advantages such as brightness and excellent color fastness. A recative textile dye, called Everzol Black, was used in this study. The low-cost mollasses medium is used for fungal growth. The usage of mollases, the sugar refinery effluent as a source of energy and nutrients, gained importance because of reducing the cost and also reusing another waste. In biosorption process the effect of surfactant on dye removal properties of T. versicolor was examined as a function of pH, dye consentration and surfactant concentration. The results of this study showed that the surfactant enhanced the dye removal capacity of Trametes versicolor. The dye and surfactant molecules were interacted electrostatically and these electrostatic interactions improved dye removal properties of filamentous fungus T. versicolor. The results of this study recommended the use of surfactants as an inducer in textile wastewater treatment technologies.

Atrazine and Diuron partitioning within a soil-water-surfactant system

Science.gov (United States)

Wang, P.; Keller, A.

2006-12-01

The interaction between pesticide and soil and water is even more complex in the presence of surfactants. In this study, batch equilibrium was employed to study the sorption of surfactants and the partitioning behaviors of Atrazine and Diuron within a soil-water-surfactant system. Five soils and four surfactants (nonionic Triton- 100, cationic Benzalkonium Chloride (BC), anionic Linear Alkylbenzenesulfonate (LAS), and anionic Sodium Dodecyl Sulfate (SDS)) were used. All surfactant sorption isotherms exhibited an initial linear increase at low surfactant concentrations but reached an asymptotic value as the surfactant concentrations increased. Among the surfactants, BC had the highest sorption onto all soils, followed by Triton-100 and then by LAS and SDS, implying that the nature of the charge significantly influences surfactant sorption. Sorption of either Triton-100 or BC was highly correlated with soil Cation Exchange Capacity (CEC) while that of LAS and SDS was complicated by the presence of Ca2+ and Mg2+ in the aqueous phase and the CEC sites. Both LAS and SDS formed complexes with Ca2+ and Mg2+, resulting in a significant decrease in the detergency of the surfactants. At high surfactant concentrations and with micelles present in the aqueous phase, the micelles formed a more competitive partitioning site for the pesticides, resulting in less pesticide sorbed to the soil. At low Triton-100 and BC concentration, the sorption of the surfactants first resulted in less Atrazine sorption but more Diuron sorption, implying competition between the surfactants and Atrazine, which serves as an indirect evidence that there is a different sorption mechanism for Atrazine. Atrazine is a weak base and it protonates and becomes positively charged near particle surfaces where the pH is much lower than in the bulk solution. The protonated Atrazine may then be held on the CEC sites via electrostatic attraction. Triton-100, LAS and SDS sorbed on the soil showed similar

Identifying the Imprint of Surfactant Stabilisation in Whitecap Foam Evolution

Science.gov (United States)

Callaghan, A. H.; Deane, G. B.; Stokes, D.

2016-02-01

Surfactants are ubiquitous in the world's oceans and can affect climatically-relevant processes such as air-sea gas exchange, sea spray aerosol (SSA) flux, and air-sea momentum transfer. Surfactants are amphiphilic and help form the physically and chemically distinct ocean surface microlayer (SML), however, the spatial distribution, concentration and composition of the SML is not well understood, especially under conditions of vigorous wave breaking. Like the SML, breaking waves also influence physical exchange processes at the air-sea interface, and oceanic whitecap foam coverage is commonly used to quantify bubble-mediated exchange processes. However, surfactants can increase the lifetime of foam over clean water conditions, potentially complicating the use of whitecap coverage to parameterise air-sea gas exchange and SSA production flux. A better understanding of how surfactants affect the evolution of whitecap foam is needed to improve whitecap parameterisations of bubble-mediated processes, and may also provide a remote sensing approach to map the spatial distribution of surfactants at the water surface. Here we present results from a laboratory study that looked at whitecap foam evolution in "clean" and "surfactant-added" seawater regimes. We find that the whitecap foam area growth timescale is largely insensitive to the presence of surfactants, but that surfactant stabilization of whitecap foam becomes important during the whitecap foam area decay phase. The timescale at which this occurs appears to be consistent for breaking waves of different scale and intensity. A simple method is then used to isolate the surfactant signal and derive an equivalent "clean" seawater foam decay time for the whitecaps in the "surfactant-added" regime. The method is applied to oceanic whitecaps and results compared to the laboratory whitecaps from the "clean" and "surfactant-added" regimes.

Electrostatic Screening and Charge Correlation Effects in Micellization of Ionic Surfactants

KAUST Repository

Jusufi, Arben; Hynninen, Antti-Pekka; Haataja, Mikko; Panagiotopoulos, Athanassios Z.

2009-01-01

We have used atomistic simulations to study the role of electrostatic screening and charge correlation effects in self-assembly processes of ionic surfactants into micelles. Specifically, we employed grand canonical Monte Carlo simulations

Binding affinities of cationic dyes in the presence of activated charcoal and anionic surfactant in the premicellar region

Science.gov (United States)

Ali, Farman; Ibrahim, Muhammad; Khan, Fawad; Bibi, Iram; Shah, Syed W. H.

2018-03-01

Binding preferences of cationic dyes malachite green and methylene blue in a mixed charcoal-sodium dodecyl sulfate system have been investigated using UV-visible absorption spectroscopy. The dye adsorption shows surfactant-dependent patterns, indicating diverse modes of interactions. At low surfactant concentration, a direct binding to charcoal is preferred. Comparatively greater quantities of surfactant lead to attachment of dye-surfactant complex to charcoal through hydrophobic interactions. A simple model was employed for determination of equilibrium constant K eq and concentration of dye-surfactant ion pair N DS for both dyes. The values of binding parameters revealed that malachite green was directly adsorbed onto charcoal, whereas methylene blue was bound through surfactant monomers. The model is valid for low surfactant concentrations in the premicellar region. These findings have significance for material and environmental sciences.

Application of surfactant enhanced permanganate oxidation and bidegradation of trichloroethylene in groundwater

Energy Technology Data Exchange (ETDEWEB)

Tsai, T.T.; Kao, C.M. [Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Yeh, T.Y. [Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, Taiwan (China)], E-mail: tyyeh@nuk.edu.tw; Liang, S.H.; Chien, H.Y. [Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (China)

2009-01-15

The industrial solvent trichloroethylene (TCE) is among the most ubiquitous chlorinated solvents found in groundwater contamination. The main objectives of this study were to evaluate the feasibility of using non-ionic surfactant Simple Green{sup TM} (SG) to enhance the oxidative dechlorination of TCE by potassium permanganate (KMnO{sub 4}) employing a continuous stir batch reactor system (CSBR) and column experiments. The effect of using surfactant SG to enhance the biodegradation of TCE via aerobic cometabolism was also examined. Results from CSBR experiments revealed that combination of KMnO{sub 4} with surfactant SG significantly enhanced contaminant removal, particularly when the surfactant SG concentrated at its CMC. TCE degradation rates ranged from 74.1% to 85.7% without addition of surfactant SG while TCE degradation rates increased to ranging from 83.8% to 96.3% with presence of 0.1 wt% SG. Furthermore, results from column experiments showed that TCE was degraded from 38.1 {mu}M to 6.2 {mu}M in equivalent to 83.7% of TCE oxidation during first 560 min reaction. This study has also demonstrated that the addition of surfactant SG is a feasible method to enhance bioremediation efficiency for TCE contaminated groundwater. The complete TCE degradation was detected after 75 days of incubation with both 0.01 and 0.1 wt% of surfactant SG addition. Results revealed that surfactant enhanced chemical oxidation and bioremediation technology is one of feasible approaches to clean up TCE contaminated groundwater.

Characterization of surfactant liquid crystal phases suitable for molecular alignment and measurement of dipolar couplings

International Nuclear Information System (INIS)

Barrientos, Laura G.; Dolan, Caroline; Gronenborn, Angela M.

2000-01-01

Media employed for imparting partial alignment onto solute molecules have recently attracted considerable attention, since they permit the measurement of NMR parameters for solute biomolecules commonly associated with solid state NMR. Here we characterize a medium which is based on a quasi-ternary surfactant system comprising cetylpyridinium bromide/hexanol/sodium bromide. We demonstrate that dilute solutions of this system can exist in liquid crystalline phases which orient in the magnetic field and allow the measurement of residual dipolar couplings under a variety of conditions. The present system is extremely versatile and robust, tolerating different buffer conditions, temperature ranges and concentrations

Determination of the critical micelle concentration in simulations of surfactant systems

Energy Technology Data Exchange (ETDEWEB)

Santos, Andrew P.; Panagiotopoulos, Athanassios Z., E-mail: azp@princeton.edu [Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

2016-01-28

Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the “free” (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit)

Determination of the critical micelle concentration in simulations of surfactant systems.

Science.gov (United States)

Santos, Andrew P; Panagiotopoulos, Athanassios Z

2016-01-28

Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the "free" (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit).

Determination of the critical micelle concentration in simulations of surfactant systems

International Nuclear Information System (INIS)

Santos, Andrew P.; Panagiotopoulos, Athanassios Z.

2016-01-01

Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the “free” (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit)

Relating Structure to Efficiency in Surfactant-Free Polymer/Fullerene Nanoparticle-Based Organic Solar Cells.

Science.gov (United States)

Gärtner, Stefan; Clulow, Andrew J; Howard, Ian A; Gilbert, Elliot P; Burn, Paul L; Gentle, Ian R; Colsmann, Alexander

2017-12-13

Nanoparticle dispersions open up an ecofriendly route toward printable organic solar cells. They can be formed from a variety of organic semiconductors by using miniemulsions that employ surfactants to stabilize the nanoparticles in dispersion and to prevent aggregation. However, whenever surfactant-based nanoparticle dispersions have been used to fabricate solar cells, the reported performances remain moderate. In contrast, solar cells from nanoparticle dispersions formed by precipitation (without surfactants) can exhibit power conversion efficiencies close to those of state-of-the-art solar cells processed from blend solutions using chlorinated solvents. In this work, we use small-angle neutron scattering measurements and transient absorption spectroscopy to investigate why surfactant-free nanoparticles give rise to efficient organic solar cells. We show that surfactant-free nanoparticles comprise a uniform distribution of small semiconductor domains, similar to that of bulk-heterojunction films formed using traditional solvent processing. This observation differs from surfactant-based miniemulsion nanoparticles that typically exhibit core-shell structures. Hence, the surfactant-free nanoparticles already possess the optimum morphology for efficient energy conversion before they are assembled into the photoactive layer of a solar cell. This structural property underpins the superior performance of the solar cells containing surfactant-free nanoparticles and is an important design criterion for future nanoparticle inks.

The energetics of mesopore formation in zeolites with surfactants.

Science.gov (United States)

Linares, Noemi; Jardim, Erika de Oliveira; Sachse, Alexander; Serrano, Elena; Garcia-Martinez, Javier

2018-05-02

Mesoporosity can be conveniently introduced in zeolites by treating them in basic surfactant solutions. The apparent activation energy involved in the formation of mesopores in USY via surfactant-templating was obtained through the combination of in situ synchrotron XRD and ex situ gas adsorption. Additionally, techniques such as pH measurements and TG/DTA were employed to determine the OH- evolution and the CTA+ uptake during the development of mesoporosity, providing information about the different steps involved. By combining both in situ and ex situ techniques, we have been able, for the first time, to determine the apparent activation energies of the different processes involved in the mesostructuring of USY zeolites, which are in the same order of magnitude (30 - 65 kJ mol-1) of those involved in the crystallization of zeolites. Hence, important mechanistic insights on the surfactant-templating method were obtained. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Conductive Hybrid Crystal Composed from Polyoxomolybdate and Deprotonatable Ionic-Liquid Surfactant

Directory of Open Access Journals (Sweden)

Jun Kobayashi

2016-06-01

Full Text Available A polyoxomolybdate inorganic-organic hybrid crystal was synthesized with deprotonatable ionic-liquid surfactant. 1-dodecylimidazolium cation was employed for its synthesis. The hybrid crystal contained δ-type octamolybdate (Mo8 isomer, and possessed alternate stacking of Mo8 monolayers and interdigitated surfactant bilayers. The crystal structure was compared with polyoxomolybdate hybrid crystals comprising 1-dodecyl-3-methylimidazolium surfactant, which preferred β-type Mo8 isomer. The less bulky hydrophilic moiety of the 1-dodecylimidazolium interacted with the δ-Mo8 anion by N–H···O hydrogen bonds, which presumably induced the formation of the δ-Mo8 anion. Anhydrous conductivity of the hybrid crystal was estimated to be 5.5 × 10−6 S·cm−1 at 443 K by alternating current (AC impedance spectroscopy.

Pulmonary surfactant and lung transplantation

NARCIS (Netherlands)

Erasmus, Michiel Elardus

1997-01-01

Pulmonary surfactant lowers the surface tension at the air-water interface inside the alveolus. This is achieved by adsorption of surfactant phospholipids at the air-water interface, a process controlled by surfactant-associated proteins, such as SP-A. In this way, surfactant prevents collapse of

Reducing plant uptake of PAHs by cationic surfactant-enhanced soil retention

Energy Technology Data Exchange (ETDEWEB)

Lu Li, E-mail: ll19840106@zju.edu.c [Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310028 (China); Zhu Lizhong, E-mail: zlz@zju.edu.c [Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310028 (China); Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, Zhejiang University, Hangzhou, Zhejiang 310029 (China)

2009-06-15

Reducing the transfer of contaminants from soils to plants is a promising approach to produce safe agricultural products grown on contaminated soils. In this study, 0-400 mg/kg cetyltrimethylammonium bromide (CTMAB) and dodecylpyridinium bromide (DDPB) were separately utilized to enhance the sorption of PAHs onto soils, thereby reducing the transfer of PAHs from soil to soil solution and subsequently to plants. Concentrations of phenanthrene and pyrene in vegetables grown in contaminated soils treated with the cationic surfactants were lower than those grown in the surfactant-free control. The maximum reductions of phenanthrene and pyrene were 66% and 51% for chrysanthemum (Chrysanthemum coronarium L.), 62% and 71% for cabbage (Brassica campestris L.), and 34% and 53% for lettuce (Lactuca sativa L.), respectively. Considering the impacts of cationic surfactants on plant growth and soil microbial activity, CTMAB was more appropriate to employ, and the most effective dose was 100-200 mg/kg. - Cationic surfactants could enhance the retention of PAHs in soil, and reduce PAH transfer to and accumulation in vegetables.

Reducing plant uptake of PAHs by cationic surfactant-enhanced soil retention

International Nuclear Information System (INIS)

Lu Li; Zhu Lizhong

2009-01-01

Reducing the transfer of contaminants from soils to plants is a promising approach to produce safe agricultural products grown on contaminated soils. In this study, 0-400 mg/kg cetyltrimethylammonium bromide (CTMAB) and dodecylpyridinium bromide (DDPB) were separately utilized to enhance the sorption of PAHs onto soils, thereby reducing the transfer of PAHs from soil to soil solution and subsequently to plants. Concentrations of phenanthrene and pyrene in vegetables grown in contaminated soils treated with the cationic surfactants were lower than those grown in the surfactant-free control. The maximum reductions of phenanthrene and pyrene were 66% and 51% for chrysanthemum (Chrysanthemum coronarium L.), 62% and 71% for cabbage (Brassica campestris L.), and 34% and 53% for lettuce (Lactuca sativa L.), respectively. Considering the impacts of cationic surfactants on plant growth and soil microbial activity, CTMAB was more appropriate to employ, and the most effective dose was 100-200 mg/kg. - Cationic surfactants could enhance the retention of PAHs in soil, and reduce PAH transfer to and accumulation in vegetables.

Microemulsion-based lycopene extraction: Effect of surfactants, co-surfactants and pretreatments.

Science.gov (United States)

Amiri-Rigi, Atefeh; Abbasi, Soleiman

2016-04-15

Lycopene is a potent antioxidant that has received extensive attention recently. Due to the challenges encountered with current methods of lycopene extraction using hazardous solvents, industry calls for a greener, safer and more efficient process. The main purpose of present study was application of microemulsion technique to extract lycopene from tomato pomace. In this respect, the effect of eight different surfactants, four different co-surfactants, and ultrasound and enzyme pretreatments on lycopene extraction efficiency was examined. Experimental results revealed that application of combined ultrasound and enzyme pretreatments, saponin as a natural surfactant, and glycerol as a co-surfactant, in the bicontinuous region of microemulsion was the optimal experimental conditions resulting in a microemulsion containing 409.68±0.68 μg/glycopene. The high lycopene concentration achieved, indicates that microemulsion technique, using a low-cost natural surfactant could be promising for a simple and safe separation of lycopene from tomato pomace and possibly from tomato industrial wastes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Dicationic alkylammonium bromide gemini surfactants. Membrane perturbation and skin irritation.

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João A S Almeida

Full Text Available Dicationic alkylammonium bromide gemini surfactants represent a class of amphiphiles potentially effective as skin permeation enhancers. However, only a limited number of studies has been dedicated to the evaluation of the respective cytotoxicity, and none directed to skin irritation endpoints. Supported on a cell viability study, the cytotoxicity of gemini surfactants of variable tail and spacer length was assessed. For this purpose, keratinocyte cells from human skin (NCTC 2544 cell line, frequently used as a model for skin irritation, were employed. The impact of the different gemini surfactants on the permeability and morphology of model vesicles was additionally investigated by measuring the leakage of calcein fluorescent dye and analyzing the NMR spectra of ³¹P, respectively. Detail on the interaction of gemini molecules with model membranes was also provided by a systematic differential scanning calorimetry (DSC and molecular dynamics (MD simulation. An irreversible impact on the viability of the NCTC 2544 cell line was observed for gemini concentrations higher than 25 mM, while no cytotoxicity was found for any of the surfactants in a concentration range up to 10 mM. A higher cytotoxicity was also found for gemini surfactants presenting longer spacer and shorter tails. The same trend was obtained in the calorimetric and permeability studies, with the gemini of longest spacer promoting the highest degree of membrane destabilization. Additional structural and dynamical characterization of the various systems, obtained by ³¹P NMR and MD, provide some insight on the relationship between the architecture of gemini surfactants and the respective perturbation mechanism.

Structure and Conformational Dynamics of DMPC/Dicationic Surfactant and DMPC/Dicationic Surfactant/DNA Systems

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Maciej Kozak

2013-04-01

Full Text Available Amphiphilic dicationic surfactants, known as gemini surfactants, are currently studied for gene delivery purposes. The gemini surfactant molecule is composed of two hydrophilic “head” groups attached to hydrophobic chains and connected via molecular linker between them. The influence of different concentrations of 1,5-bis (1-imidazolilo-3-decyloxymethyl pentane chloride (gemini surfactant on the thermotropic phase behaviour of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC bilayers with and without the presence of DNA was investigated using Fourier transformed infrared (FTIR and circular dichroism (CD spectroscopies, small angle scattering of synchrotron radiation and differential scanning calorimetry. With increasing concentration of surfactant in DMPC/DNA systems, a disappearance of pretransition and a decrease in the main phase transition enthalpy and temperature were observed. The increasing intensity of diffraction peaks as a function of surfactant concentration also clearly shows the ability of the surfactant to promote the organisation of lipid bilayers in the multilayer lamellar phase.

Surfactant Membrane Phases Containing Mixtures of Hydrocarbon and Fluorocarbon Surfactants

International Nuclear Information System (INIS)

de Campo, Liliana; Warr, G.G.

2005-01-01

Full text: We describe the structure and stability of sponge and lamellar phases comprising mixtures of hydrocarbon and fluorocarbon surfactants. Such mixtures can show limited miscibility with each other, forming for example coexisting populations of hydrocarbon rich and fluorocarbon rich micelles under some circumstances. Our system is based on the well-characterised lamellar and sponge phases of cetylpyridinium chloride, hexanol and 0.2M brine, into which the partially fluorinated surfactant N-1H,1H,2H,2H-tridecafluorooctylpyridinium chloride is incorporated. By probing the structures with SAXS (small angle x-ray scattering) and SANS (small angle neutron scattering) using contrast variation, and by characterizing the dynamic properties with dynamic light scattering, we will describe the effect of incorporating the fluorinated surfactant on the phase equilibria and properties of the surfactant membrane structures. (authors)

Surfactant-Mediated Growth Revisited

International Nuclear Information System (INIS)

Meyerheim, H. L.; Sander, D.; Popescu, R.; Pan, W.; Kirschner, J.; Popa, I.

2007-01-01

The x-ray structure analysis of the oxygen-surfactant-mediated growth of Ni on Cu(001) identifies up to 0.15 monolayers of oxygen in subsurface octahedral sites. This questions the validity of the general view that surfactant oxygen floats on top of the growing Ni film. Rather, the surfactant action is ascribed to an oxygen-enriched zone extending over the two topmost layers. Surface stress measurements support this finding. Our results have important implications for the microscopic understanding of surfactant-mediated growth and the change of the magnetic anisotropy of the Ni films

Surfactants in tribology

CERN Document Server

Biresaw, Girma

2014-01-01

Surface science and tribology play very critical roles in many industries. Manufacture and use of almost all consumer and industrial products rely on the application of advanced surface and tribological knowledge. The fourth in a series, Surfactants in Tribology, Volume 4 provides an update on research and development activities connecting surfactants and tribological phenomena. Written by renowned subject matter experts, the book demonstrates how improved design of surfactants can be harnessed to control tribological phenomena. Profusely illustrated and copiously referenced, the chapters also

Polyacrylamide grafted cellulose as an eco-friendly flocculant: Key factors optimization of flocculation to surfactant effluent.

Science.gov (United States)

Zhu, Hangcheng; Zhang, Yong; Yang, Xiaogang; Shao, Lan; Zhang, Xiumei; Yao, Juming

2016-01-01

The discharge of effluents from surfactant manufacturers is giving rise to increasingly serious environmental problems. In order to develop the eco-friendly flocculation materials to achieve effective removal of pollutants from the surfactant effluents, the bamboo pulp cellulose from Phyllostachys heterocycla is employed as the skeleton material to synthesize an eco-friendly bamboo pulp cellulose-g-polyacrylamide (BPC-g-PAM) for flocculation. The BPC-g-PAM is used with the metal ions as the coagulant to treat the effluent from a surfactant manufacturer. The response surface methodology coupled with Box-behnken design is employed to optimize the key factors of coagulation-flocculation. The results show that the combination of Fe(3+) with BPC-g-PAM achieves the best coagulation-flocculation performance like, the fast treatment time, minimum coagulant and BPC-g-PAM dosages compared with the other two combinations of Al(3+) with BPC-g-PAM and Ca(2+) with BPC-g-PAM. Therefore, the combination of Fe(3+) with BPC-g-PAM is expected to promote its application for the pollution control in the surfactant manufacturers. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of Surfactants on Mechanical, Thermal, and Photostability of a Monoclonal Antibody.

Science.gov (United States)

Agarkhed, Meera; O'Dell, Courtney; Hsieh, Ming-Ching; Zhang, Jingming; Goldstein, Joel; Srivastava, Arvind

2018-01-01

The purpose of this work was to evaluate the effect of commonly used surfactants (at 0.01% w/v concentration) on mechanical, thermal, and photostability of a monoclonal antibody (MAb1) of IgG1 sub-class and to evaluate the minimum concentration of surfactant (Polysorbate 80) required in protecting MAb1 from mechanical stress. Surfactants evaluated were non-ionic surfactants, Polysorbate 80, Polysorbate 20, Pluronic F-68 (polyoxyethylene-polyoxypropylene block polymer), Brij 35 (polyoxyethylene lauryl ether), Triton X-100, and an anionic surfactant, Caprylic acid (1-Heptanecarboxylic acid). After evaluating effect of surfactants and determining stabilizing effect of Polysorbate 80 against mechanical stress without compromising thermal and photostability of MAb1, the minimum concentration of Polysorbate 80 required for mechanical stability was further examined. Polysorbate 80 concentration was varied from 0 to 0.02%. Mechanical stability was evaluated by agitation of MAb1 at 300 rotations per minute at room temperature for 72 h. Samples were analyzed for purity by SEC-HPLC, turbidity by absorbance at 350 nm, visible particles by visual inspection, and sub-visible particles by light obscuration technique on a particle analyzer. All non-ionic surfactants tested showed a similar effect in protecting against mechanical stress and did not exhibit any significant negative effect on thermal and photostability. However, Caprylic acid had a slightly negative effect on mechanical and photostability when compared to the non-ionic surfactants or sample without surfactant. This work demonstrated that polysorbate 80 is better than other surfactants tested and that a concentration of at least 0.005% (w/v) Polysorbate 80 is needed to protect MAb1 against mechanical stress.

Surfactant replacement therapy--economic impact.

Science.gov (United States)

Pejaver, R K; al Hifzi, I; Aldussari, S

2001-06-01

Surfactant replacement is an effective treatment for neonatal respiratory distress syndrome. (RDS). As widespread use of surfactant is becoming a reality, it is important to assess the economic implications of this new form of therapy. A comparison study was carried out at the Neonatal Intensive Care Unit (NICU) of Northwest Armed Forces Hospital, Saudi Arabia. Among 75 infants who received surfactant for RDS and similar number who were managed during time period just before the surfactant was available, but by set criteria would have made them eligible for surfactant. All other management modalities except surfactant were the same for all these babies. Based on the intensity of monitoring and nursing care required by the baby, the level of care was divided as: Level IIIA, IIIB, Level II, Level I. The cost per day per bed for each level was calculated, taking into account the use of hospital immovable equipment, personal salaries of nursing, medical, ancillary staff, overheads and maintenance, depreciation and replacement costs. Medications used, procedures done, TPN, oxygen, were all added to individual patient's total expenditure. 75 infants in the Surfactant group had 62 survivors. They spent a total of 4300 days in hospital. (av 69.35) Out of which 970 d (av 15.65 per patient) were ventilated days. There were 56 survivors in the non-surfactant group of 75. They had spent a total of 5023 days in the hospital (av 89.69/patient) out of which 1490 were ventilated days (av 26.60 d). Including the cost of surfactant (two doses), cost of hospital stay for each infant taking the average figures of stay would be SR 118, 009.75 per surfactant treated baby and SR 164, 070.70 per non-surfactant treated baby. The difference of 46,061 SR is 39.03% more in non-surfactant group. One Saudi rial = 8 Rs (approx at the time study was carried out.) Medical care cost varies from place to place. However, it is definitely cost-effective where surfactant is concerned. Quality adjusted

Synthesis of Mesoporous Nanocrystalline Zirconia by Surfactant-Assisted Hydrothermal Approach.

Science.gov (United States)

Nath, Soumav; Biswas, Ashik; Kour, Prachi P; Sarma, Loka S; Sur, Ujjal Kumar; Ankamwar, Balaprasad G

2018-08-01

In this paper, we have reported the chemical synthesis of thermally stable mesoporous nanocrystalline zirconia with high surface area using a surfactant-assisted hydrothermal approach. We have employed different type of surfactants such as CTAB, SDS and Triton X-100 in our synthesis. The synthesized nanocrystalline zirconia multistructures exhibit various morphologies such as rod, mortar-pestle with different particle sizes. We have characterized the zirconia multistructures by X-ray diffraction study, Field emission scanning electron microscopy, Attenuated total refection infrared spectroscopy, UV-Vis spectroscopy and photoluminescence spectroscopy. The thermal stability of as synthesized zirconia multistructures was studied by thermo gravimetric analysis, which shows the high thermal stability of nanocrystalline zirconia around 900 °C temperature.

Surfactant -- Where Are We in 2003?

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JF Lewis

2004-01-01

Full Text Available Surfactant research has progressed over the past several years to the extent that exogenous surfactant administration in patients with the acute respiratory distress syndrome (ARDS is now being evaluated. Unfortunately, clinical responses have been variable, and we now need to take a look at how surfactant is altered in this disease so that more effective treatment strategies can be developed. This review briefly discusses the biophysical and host defense properties of surfactant, the impact of mechanical ventilation (MV on the endogenous surfactant system and the most recent clinical data involving exogenous surfactant administration in patients with ARDS. Discussions regarding future directions of surfactant research both in ARDS and diseases other than acute lung injury are included.

Thermodynamics of non-ionic surfactant Triton X-100-cationic surfactants mixtures at the cloud point

International Nuclear Information System (INIS)

Batigoec, Cigdem; Akbas, Halide; Boz, Mesut

2011-01-01

Highlights: → Non-ionic surfactants are used as emulsifier and solubilizate in such as textile, detergent and cosmetic. → Non-ionic surfactants occur phase separation at temperature as named the cloud point in solution. → Dimeric surfactants have attracted increasing attention due to their superior surface activity. → The positive values of ΔG cp 0 indicate that the process proceeds nonspontaneous. - Abstract: This study investigates the effects of gemini and conventional cationic surfactants on the cloud point (CP) of the non-ionic surfactant Triton X-100 (TX-100) in aqueous solutions. Instead of visual observation, a spectrophotometer was used for measurement of the cloud point temperatures. The thermodynamic parameters of these mixtures were calculated at different cationic surfactant concentrations. The gemini surfactants of the alkanediyl-α-ω-bis (alkyldimethylammonium) dibromide type, on the one hand, with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred to as 'm-2-m' (m = 10, 12, and 16) and, on the other hand, with -C 16 alkyl groups and different spacers containing s carbon atoms, referred to as '16-s-16' (s = 6 and 10) were synthesized, purified and characterized. Additions of the cationic surfactants to the TX-100 solution increased the cloud point temperature of the TX-100 solution. It was accepted that the solubility of non-ionic surfactant containing polyoxyethylene (POE) hydrophilic chain was a maximum at the cloud point so that the thermodynamic parameters were calculated at this temperature. The results showed that the standard Gibbs free energy (ΔG cp 0 ), the enthalpy (ΔH cp 0 ) and the entropy (ΔS cp 0 ) of the clouding phenomenon were found positive in all cases. The standard free energy (ΔG cp 0 ) increased with increasing hydrophobic alkyl chain for both gemini and conventional cationic surfactants; however, it decreased with increasing surfactant concentration.

An arbitrary Lagrangian-Eulerian method for interfacial flows with insoluble surfactants

Science.gov (United States)

Yang, Xiaofeng

Interfacial flows, fluid flows involving two or more fluids that do not mix, are common in many natural and industrial processes such as rain drop formation, crude oil recovery, polymer blending, fuel spray formation, and so on. Surfactants (surface active substances) play an important role in such processes because they significantly change the interfacial dynamics. In this thesis, an arbitrary Lagrangian-Eulerian (ALE) method has been developed to numerically simulate interfacial flows with insoluble surfactants. The interface is captured using a coupled level set and volume of fluid method. To evolve the surfactant concentration, the method directly tracks the surfactant mass and the interfacial area. The surfactant concentration, which determines the local surface tension through an equation of state, is then computed as surfactant mass per interfacial area. By directly tracking the surfactant mass, the method conserves the surfactant mass exactly. To accurately approximate the interfacial area, the fluid interface is reconstructed using piecewise parabolas. The evolution of the level set function, volume fraction, interfacial area, and the surfactant mass is performed using an ALE approach. The fluid flow is governed by Stokes equations, which are solved using a finite element method. The surface forces are included in the momentum equation using a continuum surface stress formulation. To efficiently resolve the complex interfacial dynamics, interfacial regions of high surface curvature, and near contact regions between two interacting interfaces, the grid near the interface is adaptively refined. The method is extendible to axisymmetric and 3D spaces, and can be coupled with other flow solvers, such as Navier-Stokes and viscoelastic flow solvers, as well. The method has been applied to study the effect of surfactants on drop deformation and breakup in an extensional flow. Drop deformation results are compared with available experimental and theoretical

MICROBIAL SURFACTANTS IN ENVIRONMENTAL TECHNOLOGIES

Directory of Open Access Journals (Sweden)

T. P. Pirog

2015-08-01

Full Text Available It was shown literature and own experimental data concerning the use of microbial surface active glycolipids (rhamno-, sophoro- and trehalose lipids and lipopeptides for water and soil purification from oil and other hydrocarbons, removing toxic heavy metals (Cu2+, Cd2+, Ni2+, Pb2+, degradation of complex pollution (oil and other hydrocarbons with heavy metals, and the role of microbial surfactants in phytoremediation processes. The factors that limit the use of microbial surfactants in environmental technologies are discussed. Thus, at certain concentrations biosurfactant can exhibit antimicrobial properties and inhibit microorganisms destructing xenobiotics. Microbial biodegradability of surfactants may also reduce the effectiveness of bioremediation. Development of effective technologies using microbial surfactants should include the following steps: monitoring of contaminated sites to determine the nature of pollution and analysis of the autochthonous microbiota; determining the mode of surfactant introduction (exogenous addition of stimulation of surfactant synthesis by autochthonous microbiota; establishing an optimal concentration of surfactant to prevent exhibition of antimicrobial properties and rapid biodegradation; research both in laboratory and field conditions.

Common milkweed (Asclepias syriaca L. response to sulcotrione

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Gajić-Umiljendić Jelena

2017-01-01

Full Text Available A laboratory bioassay was conducted to investigate common milkweed response to sulcotrione. Sulcotrione was applied in concentration series of 0.15-0.90 kg a.i./ha without a surfactant and with Dash® at 1 L/ha. Plants grew for 14 days, upon which period morphological (height and fresh weight and physiological parameters (content of carotenoids, chlorophyll a and chlorophyll b were measured. Visual crop injury was estimated 7 and 14 days after treatment. Sulcotrione caused leaf bleaching and reduction in pigments content in common milkweed leaves and the degree of change depended on application rates and whether it was applied with or without the surfactant. Inhibition was slightly higher in plants which were treated with a combination of herbicide and surfactant. Based on the findings in this study, common milkweed showed moderate susceptibility to the recommended field rates of sulcotrione.

Dynamic covalent surfactants

NARCIS (Netherlands)

Minkenberg, C.B.

2012-01-01

In this thesis the development of surfactant aggregates with fast exchange dynamics between the aggregated and non-aggregated state is described. Dynamic surfactant exchange plays an important role in natural systems, for instance in cell signaling, cell division, and uptake and release of cargo.

Lung surfactant levels are regulated by Ig-Hepta/GPR116 by monitoring surfactant protein D.

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Taku Fukuzawa

Full Text Available Lung surfactant is a complex mixture of lipids and proteins, which is secreted from the alveolar type II epithelial cell and coats the surface of alveoli as a thin layer. It plays a crucial role in the prevention of alveolar collapse through its ability to reduce surface tension. Under normal conditions, surfactant homeostasis is maintained by balancing its release and the uptake by the type II cell for recycling and the internalization by alveolar macrophages for degradation. Little is known about how the surfactant pool is monitored and regulated. Here we show, by an analysis of gene-targeted mice exhibiting massive accumulation of surfactant, that Ig-Hepta/GPR116, an orphan receptor, is expressed on the type II cell and sensing the amount of surfactant by monitoring one of its protein components, surfactant protein D, and its deletion results in a pulmonary alveolar proteinosis and emphysema-like pathology. By a coexpression experiment with Sp-D and the extracellular region of Ig-Hepta/GPR116 followed by immunoprecipitation, we identified Sp-D as the ligand of Ig-Hepta/GPR116. Analyses of surfactant metabolism in Ig-Hepta(+/+ and Ig-Hepta(-/- mice by using radioactive tracers indicated that the Ig-Hepta/GPR116 signaling system exerts attenuating effects on (i balanced synthesis of surfactant lipids and proteins and (ii surfactant secretion, and (iii a stimulating effect on recycling (uptake in response to elevated levels of Sp-D in alveolar space.

Treatment with exogenous surfactant stimulates endogenous surfactant synthesis in premature infants with respiratory distress syndrome

NARCIS (Netherlands)

Bunt, JEH; Carnielli, VP; Janssen, DJ; Wattimena, JLD; Hop, WC; Sauer, PJ; Zimmermann, LJI

2000-01-01

Objective: Treatment of preterm infants with respiratory distress syndrome (RDS) with exogenous surfactant has greatly improved clinical outcome. Some infants require multiple doses, and it has not been studied whether these large amounts of exogenous surfactant disturb endogenous surfactant

Adsorption of surfactant ions and binding of their counterions at an air/water interface.

Science.gov (United States)

Tagashira, Hiroaki; Takata, Youichi; Hyono, Atsushi; Ohshima, Hiroyuki

2009-01-01

An expression for the surface tension of an aqueous mixed solution of surfactants and electrolyte ions in the presence of the common ions was derived from the Helmholtz free energy of an air/water surface. By applying the equation to experimental data for the surface tension, the adsorption constant of surfactant ions onto the air/water interface, the binding constant of counterions on the surfactants, and the surface potential and surface charge density of the interface were estimated. The adsorption constant and binding constant were dependent on the species of surfactant ion and counterion, respectively. Taking account of the dependence of surface potential and surface charge density on the concentration of electrolyte, it was suggested that the addition of electrolyte to the aqueous surfactant solution brings about the decrease in the surface potential, the increase in the surface density of surfactant ions, and consequently, the decrease in the surface tension. Furthermore, it was found that the configurational entropy plays a predominant role for the surface tension, compared to the electrical work.

Surfactant nebulisation : lung function, surfactant distribution and pulmonary blood flow distribution in lung lavaged rabbits

NARCIS (Netherlands)

Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto

1997-01-01

Objective: Surfactant nebulisation is a promising alternative to surfactant instillation in newborns with the respiratory distress syndrome. Although less surfactant is deposited in the lung, it improves gas exchange, probably due to a superior distribution. We hypothesize that a more uniform

Surfactants from petroleum paraffin wax

Energy Technology Data Exchange (ETDEWEB)

Kassem, T.M.; Hussein, M.H.; El Sayed, A.S.

Paraffin wax from Egyptian petroleum was purified and then oxidized to fatty acids which were esterified to form their methyl esters, fractionated and then hydrolysed. The obtained fatty acids were converted into the corresponding primary amines which were converted with ethylene oxide to form nonionic surfactants. The prepared primary amines were also converted into tertiary amines and then converted into cationic surfactants through condensation with benzyl chloride or 1-chloromethylnaphthalene. Also, amine oxide surfactants were prepared by oxidation of the tertiary amines with hydrogen peroxide. The surface active properties of all the prepared surfactants were determined, and the effect of their chemical structure on the surfactant properties are discussed in this paper.

Ammonium Laurate Surfactant for Cleaner Deposition of Carbon Nanotubes

Energy Technology Data Exchange (ETDEWEB)

Nilsson, Hanna M. [Department of Material Science and Engineering and ‡Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States; Meany, Brendan [Department of Material Science and Engineering and ‡Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States; Ticey, Jeremy [Department of Material Science and Engineering and ‡Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States; Sun, Chuan-Fu [Department of Material Science and Engineering and ‡Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States; Wang, YuHuang [Department of Material Science and Engineering and ‡Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States; Cumings, John [Department of Material Science and Engineering and ‡Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States

2015-06-15

Experiments probing the properties of individual carbon nanotubes (CNTs) and those measuring bulk composites show vastly different results. One major issue limiting the results is that the procedures required to separate and test CNTs introduce contamination that changes the properties of the CNT. These contamination residues often come from the resist used in lithographic processing and the surfactant used to suspend and deposit the CNTs, commonly sodium dodecyl sulfate (SDS). Here we present ammonium laurate (AL), a surfactant that has previously not been used for this application, which differs from SDS only by substitution of ionic constituents but shows vastly cleaner depositions. In addition, we show that compared to SDS, AL-suspended CNTs have greater shelf stability and more selective dispersion. These results are verified using transmission electron microscopy, atomic force microscopy, ζ-potential measurements, and Raman and absorption optical spectroscopy. This surfactant is simple to prepare, and the nanotube solutions require minimal sonication and centrifugation in order to outperform SDS.

SCREENING METHODS FOR SELECTION OF SURFACTANT FORMULATIONS FOR IOR FROM FRACTURED CARBONATE RESERVOIRS

Energy Technology Data Exchange (ETDEWEB)

William A. Goddard III; Yongchun Tang; Patrick Shuler; Mario Blanco; Yongfu Wu; Seung Soon Jang

2005-07-01

This topical report presents details of the laboratory work performed to complete Task 1 of this project; developing rapid screening methods to assess surfactant performance for IOR (Improved Oil Recovery) from fractured carbonate reservoirs. The desired outcome is to identify surfactant formulations that increase the rate and amount of aqueous phase imbibition into oil-rich, oil-wet carbonate reservoir rock. Changing the wettability from oil-wet to water-wet is one key to enhancing this water-phase imbibition process that in turn recovers additional oil from the matrix portion of a carbonate reservoir. The common laboratory test to evaluate candidate surfactant formulations is to measure directly the aqueous imbibition rate and oil recovery from small outcrop or reservoir cores, but this procedure typically requires several weeks. Two methods are presented here for the rapid screening of candidate surfactant formulations for their potential IOR performance in carbonate reservoirs. One promising surfactant screening protocol is based on the ability of a surfactant solution to remove aged crude oil that coats a clear calcite crystal (Iceland Spar). Good surfactant candidate solutions remove the most oil the quickest from the chips, plus change the apparent contact angle of the remaining oil droplets on the surface that thereby indicate increased water-wetting. The other fast surfactant screening method is based on the flotation behavior of powdered calcite in water. In this test protocol, first the calcite power is pre-treated to make the surface oil-wet. The next step is to add the pre-treated powder to a test tube and add a candidate aqueous surfactant formulation; the greater the percentage of the calcite that now sinks to the bottom rather than floats, the more effective the surfactant is in changing the solids to become now preferentially water-wet. Results from the screening test generally are consistent with surfactant performance reported in the literature.

Acute Pathophysiological Effects of Intratracheal Instillation of Budesonide and Exogenous Surfactant in a Neonatal Surfactant-depleted Piglet Model

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Chia-Feng Yang

2010-08-01

Conclusions: Intratracheal instillation of surfactant or surfactant plus budesonide can improve oxygenation and pulmonary histologic outcome in neonatal surfactant-depleted lungs. The additional use of budesonide does not disturb the function of the exogenous surfactant. Intratracheal administration of a corticosteroid combined with surfactant may be an effective method for alleviating local pulmonary inflammation in severe RDS.

Surfactant flooding of diesel-contaminated soils

International Nuclear Information System (INIS)

Peters, R.W.; Montemagno, C.D.; Shem, L.; Lewis, B.A.

1991-01-01

At one installation, approximately 60,000 gallons of No. 2 diesel fuel leaked into the subsurface environment, with contamination at depths of 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. The treatability studies focused on four separate phases: (1) leachability studies on the various contaminated soil borings, (2) air stripping studies, (3) bioremediation studies, and (4) surfactant screening/surfactant flooding studies. This paper summarizes the fourth phase of this research program after initial surfactant screening of 21 surfactants. Three of the surfactants were used for the surfactant flooding studies; the results from that phase of the research program are described

Theoretical model to investigate the alkyl chain and anion dependent interactions of gemini surfactant with bovine serum albumin.

Science.gov (United States)

Vishvakarma, Vijay K; Kumari, Kamlesh; Patel, Rajan; Dixit, V S; Singh, Prashant; Mehrotra, Gopal K; Chandra, Ramesh; Chakrawarty, Anand Kumar

2015-05-15

Surfactants are used to prevent the irreversible aggregation of partially refolded proteins and they also assist in protein refolding. We have reported the design and screening of gemini surfactant to stabilize bovine serum albumin (BSA) with the help of computational tool (iGEMDOCK). A series of gemini surfactant has been designed based on bis-N-alkyl nicotinate dianion via varying the alkyl group and anion. On changing the alkyl group and anion of the surfactant, the value of Log P changes means polarity of surfactant can be tuned. Further, the virtual screening of the gemini surfactant has been carried out based on generic evolutionary method. Herein, thermodynamic data was studied to determine the potential of gemini surfactant as BSA stabilizer. Computational tools help to find out the efficient gemini surfactant to stabilize the BSA rather than to use the surfactant randomly and directionless for the stabilization. It can be confirmed through the experimental techniques. Previously, researcher synthesized one of the designed and used gemini surfactant to stabilize the BSA and their interactions were confirmed through various techniques and computational docking. But herein, the authors find the most competent gemini surfactant to stabilize BSA using computational tools on the basis of energy score. Different from the single chain surfactant, the gemini surfactants exhibit much stronger electrostatic and hydrophobic interactions with the protein and are thus effective at much lower concentrations. Based on the present study, it is expected that gemini surfactants may prove useful in the protein stabilization operations and may thus be effectively employed to circumvent the problem of misfolding and aggregation. Copyright © 2015 Elsevier B.V. All rights reserved.

The use of isothermal titration calorimetry to assess the solubility enhancement of simvastatin by a range of surfactants

International Nuclear Information System (INIS)

Patel, Rajesh; Buckton, Graham; Gaisford, Simon

2007-01-01

Surfactants are commonly used to increase the solubility of poorly water soluble drugs but the interactions between drug and surfactant can be complex and quantitative relationships can be hard to derive. One approach is to quantify the thermodynamics of interaction and relate these parameters to known solubility or dissolution rate enhancement data. Isothermal titration calorimetry (ITC) was used to measure the enthalpy and free energy of transfer of a model drug (simvastatin) to a number of surfactant (SDS, HTAB, SDCH and Brij 35) micelles. These data were then compared with the solubility enhancements determined for each surfactant using HPLC assays. As expected, there was correlation between the free energy of transfer for the drug to each surfactant and the solubility enhancement of that surfactant. Although the data set is limited, the results suggest that ITC screening of a range of surfactants against a poorly water soluble drug may allow the selection of the best potential solubilising surfactants

Partition thermodynamics of ionic surfactants between phosphatidylcholine vesicle and water phases

Science.gov (United States)

Chu, Shin-Chi; Hung, Chia-Hui; Wang, Shun-Cheng; Tsao, Heng-Kwong

2003-08-01

The partition of ionic surfactants (sodium alkyl sulfate and alkyl trimethyl ammonium bromide) between phosphatidylcholine vesicles and aqueous phase is investigated by simple conductometry under different temperatures. The experimental results can be well represented by the proposed regular solution theory and the thermodynamic parameters satisfy the thermodynamic consistency. The deviation from ideal partition is manifested through the effective interaction energy between lipid and surfactant wb, which is O(kT) large. It is found that wb rises as the alkyl chain is decreased for a specified head group. This is attributed to significant mismatch of chain lengths between surfactant and lipid molecules. The partition coefficient K declines with increasing temperature. The energy barrier from bilayer to aqueous phase, Δμ/kT∝ln K, is in the range of 16-26 kJ/mol. As the alkyl chain length is decreased for a given head group, Δμ is lowered by 1.3-1.5 kJ/mol per methylene group. Two independent analyses are employed to confirm this result. Using the thermodynamic parameters determined from experiments, the internal energy, entropy, and free energy of the partition process can be derived. Partition is essentially driven by the internal energy gain. The solubilizing ability, which is represented by the maximum surfactant-lipid ratio in the bilayer, Reb also decreases in accord with the K parameter. It is because the change in temperature influences the surfactant incorporation into the bilayer more than the formation of micelles.

Action of Monomeric/Gemini Surfactants on Free Cells and Biofilm of Asaia lannensis

Directory of Open Access Journals (Sweden)

Anna Koziróg

2017-11-01

Full Text Available We investigated the biological activity of surfactants based on quaternary ammonium compounds: gemini surfactant hexamethylene-1,6-bis-(N,N-dimethyl-N-dodecylammonium bromide (C6, synthesized by the reaction of N,N-dimethyl-N-dodecylamine with 1,6-dibromohexane, and its monomeric analogue dodecyltrimethylammonium bromide (DTAB. The experiments were performed with bacteria Asaia lannensis, a common spoilage in the beverage industry. The minimal inhibitory concentration (MIC values were determined using the tube standard two-fold dilution method. The growth and adhesive properties of bacterial cells were studied in different culture media, and the cell viability was evaluated using plate count method. Both of the surfactants were effective against the bacterial strain, but the MIC of gemini compound was significantly lower. Both C6 and DTAB exhibited anti-adhesive abilities. Treatment with surfactants at or below MIC value decreased the number of bacterial cells that were able to form biofilm, however, the gemini surfactant was more effective. The used surfactants were also found to be able to eradicate mature biofilms. After 4 h of treatment with C6 surfactant at concentration 10 MIC, the number of bacterial cells was reduced by 91.8%. The results of this study suggest that the antibacterial activity of the gemini compound could make it an effective microbiocide against the spoilage bacteria Asaia sp. in both planktonic and biofilm stages.

Action of Monomeric/Gemini Surfactants on Free Cells and Biofilm of Asaia lannensis.

Science.gov (United States)

Koziróg, Anna; Kręgiel, Dorota; Brycki, Bogumił

2017-11-22

We investigated the biological activity of surfactants based on quaternary ammonium compounds: gemini surfactant hexamethylene-1,6-bis-( N,N -dimethyl- N -dodecylammonium bromide) (C6), synthesized by the reaction of N,N -dimethyl- N- dodecylamine with 1,6-dibromohexane, and its monomeric analogue dodecyltrimethylammonium bromide (DTAB). The experiments were performed with bacteria Asaia lannensis , a common spoilage in the beverage industry. The minimal inhibitory concentration (MIC) values were determined using the tube standard two-fold dilution method. The growth and adhesive properties of bacterial cells were studied in different culture media, and the cell viability was evaluated using plate count method. Both of the surfactants were effective against the bacterial strain, but the MIC of gemini compound was significantly lower. Both C6 and DTAB exhibited anti-adhesive abilities. Treatment with surfactants at or below MIC value decreased the number of bacterial cells that were able to form biofilm, however, the gemini surfactant was more effective. The used surfactants were also found to be able to eradicate mature biofilms. After 4 h of treatment with C6 surfactant at concentration 10 MIC, the number of bacterial cells was reduced by 91.8%. The results of this study suggest that the antibacterial activity of the gemini compound could make it an effective microbiocide against the spoilage bacteria Asaia sp. in both planktonic and biofilm stages.

Effect of cationic/anionic organic surfactants on evaporation induced self assembled tin oxide nanostructured films

International Nuclear Information System (INIS)

Khun Khun, Kamalpreet; Mahajan, Aman; Bedi, R.K.

2011-01-01

Tin oxide nanostructures with well defined morphologies have been obtained through an evaporation induced self assembly process. The technique has been employed using an ultrasonic nebulizer for production of aersol and its subsequent deposition onto a heated glass substrate. The precursor used for aersol production was modified by introducing cationic and anionic surfactants namely cetyl trimethyl ammonium bromide and sodium dodecyl sulphate respectively. The effect of surfactants on the structural, electrical and optical properties of self assembled tin oxide nanostructures were investigated by using X-ray diffraction, field emission scanning electroscope microscopy, two probe technique and photoluminiscence studies. The results reveal that high concentration of surfactants in the precursor solution leads to reduction in crystallite size with significant changes in the morphology of tin oxide nanostructures. Photoluminiscence studies of the nanostructures show emissions in the visible region which exhibit marked changes in the intensities upon variation of surfactants in the precursor solutions.

Effect of cationic/anionic organic surfactants on evaporation induced self assembled tin oxide nanostructured films

Energy Technology Data Exchange (ETDEWEB)

Khun Khun, Kamalpreet [Material Science Laboratory, Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Mahajan, Aman, E-mail: dramanmahajan@yahoo.co.in [Material Science Laboratory, Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Bedi, R.K. [Material Science Laboratory, Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

2011-01-15

Tin oxide nanostructures with well defined morphologies have been obtained through an evaporation induced self assembly process. The technique has been employed using an ultrasonic nebulizer for production of aersol and its subsequent deposition onto a heated glass substrate. The precursor used for aersol production was modified by introducing cationic and anionic surfactants namely cetyl trimethyl ammonium bromide and sodium dodecyl sulphate respectively. The effect of surfactants on the structural, electrical and optical properties of self assembled tin oxide nanostructures were investigated by using X-ray diffraction, field emission scanning electroscope microscopy, two probe technique and photoluminiscence studies. The results reveal that high concentration of surfactants in the precursor solution leads to reduction in crystallite size with significant changes in the morphology of tin oxide nanostructures. Photoluminiscence studies of the nanostructures show emissions in the visible region which exhibit marked changes in the intensities upon variation of surfactants in the precursor solutions.

Fluorescent visualization of a spreading surfactant

Energy Technology Data Exchange (ETDEWEB)

Fallest, David W; Lichtenberger, Adele M; Fox, Christopher J; Daniels, Karen E, E-mail: kdaniel@ncsu.ed [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States)

2010-07-15

The spreading of surfactants on thin films is an industrially and medically important phenomenon, but the dynamics are highly nonlinear and visualization of the surfactant dynamics has been a long-standing experimental challenge. We perform the first quantitative, spatiotemporally resolved measurements of the spreading of an insoluble surfactant on a thin fluid layer. During the spreading process, we directly observe both the radial height profile of the spreading droplet and the spatial distribution of the fluorescently tagged surfactant. We find that the leading edge of a spreading circular layer of surfactant forms a Marangoni ridge in the underlying fluid, with a trough trailing the ridge as expected. However, several novel features are observed using the fluorescence technique, including a peak in the surfactant concentration that trails the leading edge, and a flat, monolayer-scale spreading film that differs from concentration profiles predicted by current models. Both the Marangoni ridge and the surfactant leading edge can be described to spread as R{approx}t{sup {delta}}. We find spreading exponents {delta}{sub H}{approx}0.30 and {delta}{sub {Gamma}}{approx}0.22 for the ridge peak and surfactant leading edge, respectively, which are in good agreement with theoretical predictions of {delta}=1/4. In addition, we observe that the surfactant leading edge initially leads the peak of the Marangoni ridge, with the peak later catching up to the leading edge.

Study of polyacrylamide-surfactant system on the water–oil interface properties and rheological properties for EOR

Directory of Open Access Journals (Sweden)

S.Z. Mahdavi

2017-12-01

Full Text Available Nowadays, due to the remarkable oil reduction in oil fields, enhanced oil recovery (EOR techniques have been considered by a large number of scientists and company. Situ oil extraction is normally done by these techniques with high efficiency. In this particular study, five different surface active agents (surfactant, two kinds of oil with various API, two kinds of sulfonated polyacrylamide, two different electrolyte solutions with various TDS and two distinctive alcohols were tested and evaluated. An optimal formulation in terms of the properties and quantity of materials has to be used in order to enhance oil recovery, achieved by investigation of surface tension and the phase behavior of mentioned substances. Rheological behavior of polymer flooding and surfactant was studied. Employing this formulation, the maximum micro emulsion of oil in water occurred. Due to the synergy between surfactant and alcohol (as a co-surfactant, relatively lower amounts of surfactants were used which led to the dip in the cost of operation, and ultimately the efficiency of operation improved.

Coupling the Alkaline-Surfactant-Polymer Technology and the Gelation Technology to Maximize Oil Production

Energy Technology Data Exchange (ETDEWEB)

Malcolm Pitts; Jie Qi; Dan Wilson; Phil Dowling; David Stewart; Bill Jones

2005-12-01

the fluid-fluid analyses with the exception of the xanthan gum-chromium acetate gels. Aluminum-polyacrylamide flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9, either in linear corefloods or in dual separate radial core, common manifold corefloods. Chromium acetate-polyacrylamide flowing and rigid tonguing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid tonguing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Chromium acetate gels were stable to injection of alkaline-surfactant-polymer solutions at 72 F, 125 F and 175 F in linear corefloods. Chromium acetate-polyacrylamide gels maintained diversion capability after injection of an alkaline-surfactant-polymer solution in stacked; radial coreflood with a common well bore. Chromium acetate-polyacrylamide gel used to seal fractured core maintain fracture closure if followed by an alkaline-surfactant-polymer solution. Chromium acetate-xanthan gum rigid gels are not stable to subsequent alkaline-surfactant-polymer solution injection at 72, 125, and 175 F. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Resorcinol-formaldehyde gels were stable to subsequent alkaline-surfactant-polymer solution injection. When evaluated in a dual core configuration, injected fluid flows into the core with the greatest effective permeability to the injected fluid. The same gel stability trends to subsequent alkaline-surfactant-polymer injected solution were observed. Aluminum citrate-polyacrylamide, resorcinol-formaldehyde, and the silicate-polyacrylamide gel systems did not produce significant incremental oil in linear corefloods. Both flowing and rigid tonguing chromium acetate-polyacrylamide gels and the xanthan gum-chromium acetate gel system produced incremental oil with the rigid tonguing

Surfactant nebulization versus instillation during high frequency ventilation in surfactant-deficient rabbits

NARCIS (Netherlands)

Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto

Surfactant nebulization improves lung function at low alveolar doses of surfactant. However, efficiency of nebulization is low, and lung deposition seems to depend on lung aeration. High frequency ventilation (HFV) has been shown to improve lung aeration. We hypothesize that the combination of HFV

Solubilization of Hydrophobic Dyes in Surfactant Solutions

Directory of Open Access Journals (Sweden)

Ali Reza Tehrani-Bagha

2013-02-01

Full Text Available In this paper, the use of surfactants for solubilization of hydrophobic organic dyes (mainly solvent and disperse dyes has been reviewed. The effect of parameters such as the chemical structures of the surfactant and the dye, addition of salt and of polyelectrolytes, pH, and temperature on dye solubilization has been discussed. Surfactant self-assemble into micelles in aqueous solution and below the concentration where this occurs—the critical micelle concentration (CMC—there is no solubilization. Above the CMC, the amount of solubilized dye increases linearly with the increase in surfactant concentration. It is demonstrated that different surfactants work best for different dyes. In general, nonionic surfactants have higher solubilization power than anionic and cationic surfactants. It is likely that the reason for the good performance of nonionic surfactants is that they allow dyes to be accommodated not only in the inner, hydrocarbon part of the micelle but also in the headgroup shell. It is demonstrated that the location of a dye in a surfactant micelle can be assessed from the absorption spectrum of the dye-containing micellar solution.

Coupling the Alkaline-Surfactant-Polymer Technology and The Gelation Technology to Maximize Oil Production

Energy Technology Data Exchange (ETDEWEB)

Malcolm Pitts; Jie Qi; Dan Wilson; Phil Dowling; David Stewart; Bill Jones

2005-12-01

the fluid-fluid analyses with the exception of the xanthan gum-chromium acetate gels. Aluminum-polyacrylamide flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9, either in linear corefloods or in dual separate radial core, common manifold corefloods. Chromium acetate-polyacrylamide flowing and rigid tonguing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid tonguing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Chromium acetate gels were stable to injection of alkaline-surfactant-polymer solutions at 72 F, 125 F and 175 F in linear corefloods. Chromium acetate-polyacrylamide gels maintained diversion capability after injection of an alkaline-surfactant-polymer solution in stacked; radial coreflood with a common well bore. Chromium acetate-polyacrylamide gel used to seal fractured core maintain fracture closure if followed by an alkaline-surfactant-polymer solution. Chromium acetatexanthan gum rigid gels are not stable to subsequent alkaline-surfactant-polymer solution injection at 72, 125, and 175 F. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Resorcinol-formaldehyde gels were stable to subsequent alkaline-surfactant-polymer solution injection. When evaluated in a dual core configuration, injected fluid flows into the core with the greatest effective permeability to the injected fluid. The same gel stability trends to subsequent alkaline-surfactant-polymer injected solution were observed. Aluminum citrate-polyacrylamide, resorcinol-formaldehyde, and the silicate-polyacrylamide gel systems did not produce significant incremental oil in linear corefloods. Both flowing and rigid tonguing chromium acetate-polyacrylamide gels and the xanthan gum-chromium acetate gel system produced incremental oil with the rigid tonguing

NMR study of the dynamics of cationic gemini surfactant 14-2-14 in mixed solutions with conventional surfactants.

Science.gov (United States)

Jiang, Yan; Lu, Xing-Yu; Chen, Hong; Mao, Shi-Zhen; Liu, Mai-Li; Luo, Ping-Ya; Du, You-Ru

2009-06-18

Three kinds of conventional surfactants, namely, two nonionic surfactants [polyethylene glycol (23) lauryl ether (Brij-35) and Triton X-100 (TX-100)], one cationic surfactant [n-tetradecyltrimethyl ammonium bromide (TTAB)], and an anionic surfactant [sodium n-dodecyl sulfate (SDS)}, were mixed into the quaternary ammonium gemini surfactant [C(14)H(29)N(+)(CH(3))(2)](2)(CH(2))(2).2Br(-) (14-2-14) in aqueous solution. The exchange rate constants between 14-2-14 molecules in the mixed micelles and those in the bulk solution were detected using two nuclear magnetic resonance (NMR) methods: one-dimensional (1D) line shape analysis and two-dimensional (2D) exchange spectroscopy (EXSY). The results obtained from these two methods were consistent. Both showed that mixing a nonionic conventional surfactant, either Brij-35 or TX-100, enhanced the exchange process between the 14-2-14 molecules in the mixed micelles and those in the bulk solution. In contrast, the anionic surfactant SDS and the cationic surfactant TTAB slowed the process slightly.

A mean-density model of ionic surfactants for the dispersion of carbon nanotubes in aqueous solutions

Science.gov (United States)

Joung, Young Soo

2018-05-01

We propose a new analytical model of ionic surfactants used for the dispersion of carbon nanotubes (CNTs) in aqueous solutions. Although ionic surfactants are commonly used to facilitate the dispersion of CNTs in aqueous solutions, understanding the dispersion process is challenging and time-consuming owing to its complexity and nonlinearity. In this work, we develop a mean-density model of ionic surfactants to simplify the calculation of interaction forces between CNTs stabilized by ionic surfactants. Using this model, we can evaluate various interaction forces between the CNTs and ionic surfactants under different conditions. The dispersion mechanism is investigated by estimating the potential of mean force (PMF) as a function of van der Waals forces, electrostatic forces, interfacial tension, and osmotic pressure. To verify the proposed model, we compare the PMFs derived using our method with those derived from molecular dynamics simulations using comparable CNTs and ionic surfactants. Notably, for stable dispersions, the osmotic pressure and interfacial energy are important for long-range and short-range interactions, respectively, in comparison with the effect of electrostatic forces. Our model effectively prescribes specific surfactants and their concentrations to achieve stable aqueous suspensions of CNTs.

Surfactant replacement therapy in a pediatric near-drowning case in manure.

Science.gov (United States)

Ugras, Meltem; Guraksin, Ozlem; Sen, Tolga Altug; Narci, Adnan; Alpay, Faruk

2012-09-01

Drowning is defined as suffocation by submersion especially in water and is a leading cause of injury-related death in children. Age groups at greatest risk are toddlers and male adolescents. It is the second most common cause of accidental death in children after road accidents. Treatment consists of resuscitation and stabilization. The use of surfactant after near-drowning in water is reported in the literature in few case reports.We report here a boy whose condition did not get better with conventional treatment, but dramatically improved after surfactant treatment after near-drowning in a fluid with manure.

SAXS and SANS studies of surfactants and reverse micelles in supercritical CO2

International Nuclear Information System (INIS)

Londono, J.D.; Dharmapurikar, R.S.; Wignall, G.D.; Cochran, H.D.

1997-01-01

Surfactants promise to extend the applicability of supercritical CO 2 (SC-CO 2 ) to processing of insoluble materials such as polymers and aqueous systems. In this short paper the authors summarize the techniques for studying surfactants and reverse micelles in SC-CO 2 using SAXS and SANS; they will describe the scattering instruments and the pressure cells for conducting these studies; they will describe the types of measurement that yield the desired characterizations; they will describe the methods of data analysis and interpretation; and they will provide illustrative results from this laboratory. Industry seeks to replace common organic solvents now used in many reaction and separation processes; SC-CO 2 is a potential solvent substitute widely favored by both government and industry. The currently available surfactants are limited in number and performance. In ongoing work the authors are coupling their SAXS and SANS scattering studies with complementary molecular simulations in efforts to understand, at a molecular level, what surfactant characteristics lead to improved performance. They hope that superior surfactants for use in SC-CO 2 can be designed and synthesized based on this new level of understanding

Role of surfactant on thermoelectric behaviors of organic-inorganic composites

Science.gov (United States)

Shin, Sunmi; Roh, Jong Wook; Kim, Hyun-Sik; Chen, Renkun

2018-05-01

Hybrid organic/inorganic composites have recently attracted intensive interests as a promising candidate for flexible thermoelectric (TE) devices using inherently soft polymers as well as for increasing the degree of freedom to control TE properties. Experimentally, however, enhanced TE performance in hybrid composites has not been commonly observed, primarily due to inhomogeneous mixing between the inorganic and organic components which leads to limited electrical conduction in the less conductive component and consequently a low power factor in the composites compared to their single-component counterparts. In this study, we investigated the effects of different surfactants on the uniformity of mixing and the TE behaviors of the hybrid composites consisting of Bi0.5Sb1.5Te3 (BST) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). We found that compared to dimethyl sulfoxide, which is the most widely used surfactant, Triton X-100 (TX-100) can lead to homogenous dispersion of BST in PEDOT:PSS. By systematically studying the effects of the surfactant concentration, we can attribute the better mixing capability of TX-100 to its non-ionic property, which results in homogenous mixing with a lower critical micelle concentration. Consequently, we observed simultaneous increase in electrical conductivity and Seebeck coefficient in the BST/PEDOT:PSS composites with the TX-100 surfactant.

Microbial production of surfactants and their commercial potential.

OpenAIRE

Desai, J D; Banat, I M

1997-01-01

Many microorganisms, especially bacteria, produce biosurfactants when grown on water-immiscible substrates. Biosurfactants are more effective, selective, environmentally friendly, and stable than many synthetic surfactants. Most common biosurfactants are glycolipids in which carbohydrates are attached to a long-chain aliphatic acid, while others, like lipopeptides, lipoproteins, and heteropolysaccharides, are more complex. Rapid and reliable methods for screening and selection of biosurfactan...

Exchange of Surfactant by Natural Organic Matter on the Surfaces of Multi-Walled Carbon Nanotubes

Science.gov (United States)

The increasing production and applications of multi-walled carbon nanotubes (MWCNTs) have elicited concerns regarding their release and potential adverse effects in the environment. To form stable aqueous MWCNTs suspensions, surfactants are often employed to facilitate dispersion...

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

Science.gov (United States)

Mendenhall, Jonathan D.

'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)

Pulmonary clearance of {sup 99m}Tc-DTPA in experimental surfactant dysfunction treated with surfactant installation

Energy Technology Data Exchange (ETDEWEB)

Nilsson, K.; John, J.; Lachmann, B.; Robertson, B.; Wollmer, P.

1997-02-01

Background: Breakdown of the alveolo-capillary barrier is a characteristic feature of respiratory distress syndrome. Restoration of alveolo-capillary barrier function may be an important aspect of surfactant replacement therapy. We examined the effect of surfactant installation on alveolo-capillary barrier function in an experimental model of surfactant dysfunction by measuring pulmonary clearance of {sup 99m}Tc-DTPA. Methods: Nineteen rabbits were tracheotomized and mechanically ventilated. Surfactant dysfunction was induced by administration of a synthetic detergent in aerosol form. Detergent was given to 13 rabbits; seven rabbits were then treated with installation of natural surfactant, whereas six rabbits received saline. Six rabbits were used as untreated controls. An aerosol of {sup 99m}Tc-DTPA was administered to all animals and the pulmonary clearance was measured with a gamma camera. Results: {sup 99m}Tc-DTPA cleared from the lungs with a half-life of 71{+-}22 min in the control animals, 21.4{+-}7.4 min in the surfactant-treated animals and 5.8{+-}1.5 min in the saline-treated animals. The difference in half-life between groups was highly significant (P<0.001). There was no change in arterial oxygenation or compliance in controls or in animals treated with saline. In animals treated with surfactant, a small transient reduction in arterial oxygen tension and a more long-standing reduction in compliance were observed. Conclusion: Surfactant treatment thus significantly attenuated the effect of detergent treatment but did not restore alveolo-capillary transfer of {sup 99m}Tc-DTPA to normal. (AU) 26 refs.

[Determination of contact angle of pharmaceutical excipients and regulating effect of surfactants on their wettability].

Science.gov (United States)

Hua, Dong-dong; Li, He-ran; Yang, Bai-xue; Song, Li-na; Liu, Tiao-tiao; Cong, Yu-tang; Li, San-ming

2015-10-01

To study the effects of surfactants on wettability of excipients, the contact angles of six types of surfactants on the surface of two common excipients and mixture of three surfactants with excipients were measured using hypsometry method. The results demonstrated that contact angle of water on the surface of excipients was associated with hydrophilcity of excipients. Contact angle was lowered with increase in hydrophilic groups of excipient molecules. The sequence of contact angle from small to large was starch contact angle of excipients, and their abilities to lower contact angle varied. The results of the present study offer a guideline in the formulation design of tablets.

Surfactant protein A and surfactant protein D variation in pulmonary disease

DEFF Research Database (Denmark)

Sørensen, Grith Lykke; Husby, Steffen; Holmskov, Uffe

2007-01-01

Surfactant proteins A (SP-A) and D (SP-D) have been implicated in pulmonary innate immunity. The proteins are host defense lectins, belonging to the collectin family which also includes mannan-binding lectin (MBL). SP-A and SP-D are pattern-recognition molecules with the lectin domains binding...... lavage and blood have indicated associations with a multitude of pulmonary inflammatory diseases. In addition, accumulating evidence in mouse models of infection and inflammation indicates that recombinant forms of the surfactant proteins are biologically active in vivo and may have therapeutic potential...... in controlling pulmonary inflammatory disease. The presence of the surfactant collectins, especially SP-D, in non-pulmonary tissues, such as the gastrointestinal tract and genital organs, suggest additional actions located to other mucosal surfaces. The aim of this review is to summarize studies on genetic...

Adsorption of dimeric surfactants in lamellar silicates

Energy Technology Data Exchange (ETDEWEB)

Balcerzak, Mateusz; Pietralik, Zuzanna [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Domka, Ludwik [Department of Metalorganic Chemistry, Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań (Poland); Skrzypczak, Andrzej [Institute of Chemical Technology, Poznań University of Technology, Berdychowo 4, 60-965 Poznań (Poland); Kozak, Maciej, E-mail: mkozak@amu.edu.pl [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland)

2015-12-01

Highlights: • The intercalation of dimeric surfactants changed the morphology of MMT samples. • XRD indicated structures formed by surfactant molecules in interlayer space. • The four-step thermal decomposition of dimeric surfactant, confirms intercalation. - Abstract: The adsorption of different types of cationic surfactants in lamellar silicates changes their surface character from hydrophilic to hydrophobic. This study was undertaken to obtain lamellar silicates modified by a series of novel dimeric (gemini) surfactants of different length alkyl chains and to characterise these organophilised materials. Synthetic sodium montmorillonite SOMASIF® ME 100 (M) and enriched bentonite of natural origin (Nanoclay – hydrophilic bentonite®) were organophilised with dimeric (gemini) surfactants (1,1′-(1,4-butanediyl)bis(alkoxymethyl)imidazolium dichlorides). As a result of surfactant molecule adsorption in interlamellar space, the d-spacing (d{sub 001}) increased from 0.97 nm (for the anhydrous structure) to 2.04 nm. A Fourier transform infrared spectroscopy (FTIR) analysis of the modified systems reveals bands assigned to the stretching vibrations of the CH{sub 2} and CH{sub 3} groups and the scissoring vibrations of the NH group from the structure of the dimeric surfactants. Thermogravimetric (TG) and derivative thermogravimetric (DTG) studies imply a four-stage process of surfactant decomposition. Scanning electron microscopy (SEM) images provide information on the influence of dimeric surfactant intercalation into the silicate structures. Particles of the modified systems show a tendency toward the formation of irregularly shaped agglomerates.

Role of adsorbed surfactant in the reaction of aryl diazonium salts with single-walled carbon nanotubes.

Science.gov (United States)

Hilmer, Andrew J; McNicholas, Thomas P; Lin, Shangchao; Zhang, Jingqing; Wang, Qing Hua; Mendenhall, Jonathan D; Song, Changsik; Heller, Daniel A; Barone, Paul W; Blankschtein, Daniel; Strano, Michael S

2012-01-17

stabilize the diazonium ion near the nanotube surface. Such Coulombic and surfactant packing effects offer promise toward employing surfactants to controllably functionalize carbon nanotubes. © 2011 American Chemical Society

Influence of Surfactant Structure on the Stability of Water-in-Oil Emulsions under High-Temperature High-Salinity Conditions

Directory of Open Access Journals (Sweden)

Abdelhalim I. A. Mohamed

2017-01-01

Full Text Available Emulsified water-in-oil (W/O systems are extensively used in the oil industry for water control and acid stimulation. Emulsifiers are commonly utilized to emulsify a water-soluble material to form W/O emulsion. The selection of a particular surfactant for such jobs is critical and certainly expensive. In this work, the impact of surfactant structure on the stability of W/O emulsions is investigated using the hydrophilic-lipophilic balance (HLB of the surfactant. Different commercial surfactants were evaluated for use as emulsifiers for W/O systems at high-temperature (up to 120°C high-salinity (221,673 ppm HTHS conditions. Diverse surfactants were examined including ethoxylates, polyethylene glycols, fluorinated surfactants, and amides. Both commercial Diesel and waste oil are used for the oleic phase to prepare the emulsified system. Waste oil has shown higher stability (less separation in comparison with Diesel. This work has successfully identified stable emulsified W/O systems that can tolerate HTHS environments using HLB approach. Amine Acetate family shows higher stability in comparison with Glycol Ether family and at even lower concentration. New insights into structure-surfactant stability relationship, beyond the HLB approach, are provided for surfactant selection.

Estimation hydrophilic-lipophilic balance number of surfactants

Energy Technology Data Exchange (ETDEWEB)

Pawignya, Harsa, E-mail: harsa-paw@yahoo.co.id [Chemical Engineering Department Diponegoro University (Indonesia); Chemical Engineering Departement University of Pembangunan Nasional Yogyakarta (Indonesia); Prasetyaningrum, Aji, E-mail: ajiprasetyaningrum@gmail.com; Kusworo, Tutuk D.; Pramudono, Bambang, E-mail: Pramudono2004@yahoo.com [Chemical Engineering Department Diponegoro University (Indonesia); Dyartanti, Endah R. [Chemical Engineering Department Diponegoro University (Indonesia); Chemical Enginering Departement Sebelas Maret University (Indonesia)

2016-02-08

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

Degradation of surfactants by sono-irradiation

International Nuclear Information System (INIS)

Ashokkumar, M.; Grieser, F.; Vinodgopal, K.

2000-01-01

Full text: The ultrasound induced decomposition of a commercially available polydisperse nonylphenol ethoxylate surfactant (Teric GN9) has been investigated. Nearly 90% mineralization and/or degradation into volatile products of the surfactant is achieved after sonication for 24 hours. Ultrasound has been found to be a useful tool to achieve a number of chemical processes. Linear and branched alkyl benzene sulfonates and alkyl nonylphenol ethoxylates are widely used surfactants which accumulated in the environment and contribute to a well-recognised pollution problem. We have investigated the use of ultrasound in the degradation of both types of surfactants with the aim of understanding the mechanism of degradation in order to optimise the decomposition process. In this presentation, we report on the sonochemical degradation of Teric GN9- polydisperse, a nonylphenol ethoxylate with an average of 9 ethylene oxide units. The ultrasound unit used for the degradation studies of the surfactant solutions was an Allied Signal (ELAC Nautik) RF generator and transducer with a plate diameter of 54.5 mm operated at 363 kHz in continuous wave mode at an intensity of 2 W/cm 2 . Ultrasound induced cavitation events generate primary radicals inside gas/vapour filled bubbles. Due to the extreme conditions (T ∼ 5000 K; P ∼ 100 atm) generated within the collapsing bubble, H and OH radicals are produced by the homolysis of water molecules, if water is the medium of sonication. These primary radicals attack the surfactant molecules adsorbed at the bubble/water interface. The initial rate of reaction of the surfactant was found to be dependent on the monomer concentration in solution below and above the critical micelle concentration of the surfactants. This result strongly suggests that the initial radical attack on the surfactants occurs at the cavitation bubble/solution interface, followed by oxidative decomposition and pyrolysis of volatile fragments of the surfactant within

Lung surfactant microbubbles increase lipophilic drug payload for ultrasound-targeted delivery.

Science.gov (United States)

Sirsi, Shashank R; Fung, Chinpong; Garg, Sumit; Tianning, Mary Y; Mountford, Paul A; Borden, Mark A

2013-01-01

The cavitation response of circulating microbubbles to targeted ultrasound can be used for noninvasive, site-specific delivery of shell-loaded materials. One challenge for microbubble-mediated delivery of lipophilic compounds is the limitation of drug loading into the microbubble shell, which is commonly a single phospholipid monolayer. In this study, we investigated the use of natural lung surfactant extract (Survanta(®), Abbott Nutrition) as a microbubble shell material in order to improve drug payload and delivery. Pulmonary surfactant extracts such as Survanta contain hydrophobic surfactant proteins (SP-B and SP-C) that facilitate lipid folding and retention on lipid monolayers. Here, we show that Survanta-based microbubbles exhibit wrinkles in bright-field microscopy and increased lipid retention on the microbubble surface in the form of surface-associated aggregates observed with fluorescence microscopy. The payload of a model lipophilic drug (DiO), measured by flow cytometry, increased by over 2-fold compared to lipid-coated microbubbles lacking SP-B and SP-C. Lung surfactant microbubbles were highly echogenic to contrast enhanced ultrasound imaging at low acoustic intensities. At higher ultrasound intensity, excess lipid was observed to be acoustically cleaved for localized release. To demonstrate targeting, a biotinylated lipopolymer was incorporated into the shell, and the microbubbles were subjected to a sequence of radiation force and fragmentation pulses as they passed through an avidinated hollow fiber. Lung surfactant microbubbles showed a 3-fold increase in targeted deposition of the model fluorescent drug compared to lipid-only microbubbles. Our results demonstrate that lung surfactant microbubbles maintain the acoustic responsiveness of lipid-coated microbubbles with the added benefit of increased lipophilic drug payload.

Poly(ethylene oxide) surfactant polymers.

Science.gov (United States)

Vacheethasanee, Katanchalee; Wang, Shuwu; Qiu, Yongxing; Marchant, Roger E

2004-01-01

We report on a series of structurally well-defined surfactant polymers that undergo surface-induced self-assembly on hydrophobic biomaterial surfaces. The surfactant polymers consist of a poly(vinyl amine) backbone with poly(ethylene oxide) and hexanal pendant groups. The poly(vinyl amine) (PVAm) was synthesized by hydrolysis of poly(N-vinyl formamide) following free radical polymerization of N-vinyl formamide. Hexanal and aldehyde-terminated poly(ethylene oxide) (PEO) were simultaneously attached to PVAm via reductive amination. Surfactant polymers with different PEO:hexanal ratios and hydrophilic/hydrophobic balances were prepared, and characterized by FT-IR, 1H-NMR and XPS spectroscopies. Surface active properties at the air/water interface were determined by surface tension measurements. Surface activity at a solid surface/water interface was demonstrated by atomic force microscopy, showing epitaxially molecular alignment for surfactant polymers adsorbed on highly oriented pyrolytic graphite. The surfactant polymers described in this report can be adapted for simple non-covalent surface modification of biomaterials and hydrophobic surfaces to provide highly hydrated interfaces.

Dilute Surfactant Methods for Carbonate Formations

Energy Technology Data Exchange (ETDEWEB)

Kishore K. Mohanty

2006-02-01

There are many fractured carbonate reservoirs in US (and the world) with light oil. 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%). The process of using dilute anionic surfactants in alkaline solutions has been investigated in this work for oil recovery from fractured oil-wet carbonate reservoirs both experimentally and numerically. This process is a surfactant-aided gravity drainage where surfactant diffuses into the matrix, lowers IFT and contact angle, which decrease capillary pressure and increase oil relative permeability enabling gravity to drain the oil up. Anionic surfactants have been identified which at dilute concentration of 0.05 wt% and optimal salinity can lower the interfacial tension and change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant DTAB with a West Texas crude oil. The force of adhesion in AFM of oil-wet regions changes after anionic surfactant treatment to values similar to those of water-wet regions. The AFM topography images showed that the oil-wetting material was removed from the surface by the anionic surfactant treatment. Adsorption studies indicate that the extent of adsorption for anionic surfactants on calcite minerals decreases with increase in pH and with decrease in salinity. Surfactant adsorption can be minimized in the presence of Na{sub 2}CO{sub 3}. Laboratory-scale surfactant brine imbibition experiments give high oil recovery (20-42% OOIP in 50 days; up to 60% in 200 days) for initially oil-wet cores through wettability alteration and IFT reduction. Small (<10%) initial gas saturation does not affect significantly the rate of oil recovery in the imbibition process, but larger gas saturation decreases the oil recovery rate. As the core permeability decreases, the rate of oil recovery reduces

Surfactant gene polymorphisms and interstitial lung diseases

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Pantelidis Panagiotis

2001-11-01

Full Text Available Abstract Pulmonary surfactant is a complex mixture of phospholipids and proteins, which is present in the alveolar lining fluid and is essential for normal lung function. Alterations in surfactant composition have been reported in several interstitial lung diseases (ILDs. Furthermore, a mutation in the surfactant protein C gene that results in complete absence of the protein has been shown to be associated with familial ILD. The role of surfactant in lung disease is therefore drawing increasing attention following the elucidation of the genetic basis underlying its surface expression and the proof of surfactant abnormalities in ILD.

Formation and characterization of zein-propylene glycol alginate-surfactant ternary complexes: Effect of surfactant type.

Science.gov (United States)

Dai, Lei; Sun, Cuixia; Wei, Yang; Zhan, Xinyu; Mao, Like; Gao, Yanxiang

2018-08-30

In this study, zein, propylene glycol alginate (PGA) and surfactant ternary complexes were fabricated by antisolvent co-precipitation method. Two types of surfactants (rhamnolipid and lecithin) were applied to generate zein-PGA-rhamnolipid (Z-P-R) and zein-PGA-lecithin (Z-P-L) ternary complexes, respectively. Results showed that the surfactant types significantly affected the properties of ternary complexes. The formation of ternary complexes was mainly due to the non-covalent interactions such as hydrogen bonding, electrostatic interaction and hydrophobic interactions among zein, PGA and surfactants. Moreover, the thermal stability of ternary complexes was enhanced with increasing the levels of both surfactants. Notably, ternary complex dispersions exhibited better stability against pH from 2 to 8. Furthermore, a compact network structure was observed in Z-P-R ternary complex, while Z-P-L ternary complex remained the spherical structure. These findings would provide new insights into the development of novel delivery system and expand the options, when zein-based complexes were utilized under different environment conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biomimicry of surfactant protein C.

Science.gov (United States)

Brown, Nathan J; Johansson, Jan; Barron, Annelise E

2008-10-01

Since the widespread use of exogenous lung surfactant to treat neonatal respiratory distress syndrome, premature infant survival and respiratory morbidity have dramatically improved. Despite the effectiveness of the animal-derived surfactant preparations, there still remain some concerns and difficulties associated with their use. This has prompted investigation into the creation of synthetic surfactant preparations. However, to date, no clinically used synthetic formulation is as effective as the natural material. This is largely because the previous synthetic formulations lacked analogues of the hydrophobic proteins of the lung surfactant system, SP-B and SP-C, which are critical functional constituents. As a result, recent investigation has turned toward the development of a new generation of synthetic, biomimetic surfactants that contain synthetic phospholipids along with a mimic of the hydrophobic protein portion of lung surfactant. In this Account, we detail our efforts in creating accurate mimics of SP-C for use in a synthetic surfactant replacement therapy. Despite SP-C's seemingly simple structure, the predominantly helical protein is extraordinarily challenging to work with given its extreme hydrophobicity and structural instability, which greatly complicates the creation of an effective SP-C analogue. Drawing inspiration from Nature, two promising biomimetic approaches have led to the creation of rationally designed biopolymers that recapitulate many of SP-C's molecular features. The first approach utilizes detailed SP-C structure-activity relationships and amino acid folding propensities to create a peptide-based analogue, SP-C33. In SP-C33, the problematic and metastable polyvaline helix is replaced with a structurally stable polyleucine helix and includes a well-placed positive charge to prevent aggregation. SP-C33 is structurally stable and eliminates the association propensity of the native protein. The second approach follows the same design

Surfactant-aided recovery/in situ bioremediation for oil-contaminated sites

International Nuclear Information System (INIS)

Ducreaux, J.; Baviere, M.; Seabra, P.; Razakarisoa, O.; Shaefer, G.; Arnaud, C.

1995-01-01

Bioremediation has been the most commonly used method way for in situ cleaning of soils contaminated with low-volatility petroleum products such as diesel oil. However, whatever the process (bioventing, bioleaching, etc.), it is a time-consuming technique that may be efficiency limited by both accessibility and too high concentrations of contaminants. A currently developed process aims at quickly recovering part of the residual oil in the vadose and capillary zones by surfactant flushing, then activating in situ biodegradation of the remaining oil in the presence of the same or other surfactants. The process has been tested in laboratory columns and in an experimental pool, located at the Institut Franco-Allemand de Recherche sur l'Environnement (IFARE) in Strasbourg, France. Laboratory column studies were carried out to fit physico-chemical and hydraulic parameters of the process to the field conditions. The possibility of recovering more than 80% of the oil in the flushing step was shown. For the biodegradation step, forced aeration as a mode of oxygen supply, coupled with nutrient injection aided by surfactants, was tested

Remediation using trace element humate surfactant

Energy Technology Data Exchange (ETDEWEB)

Riddle, Catherine Lynn; Taylor, Steven Cheney; Bruhn, Debra Fox

2016-08-30

A method of remediation at a remediation site having one or more undesirable conditions in which one or more soil characteristics, preferably soil pH and/or elemental concentrations, are measured at a remediation site. A trace element humate surfactant composition is prepared comprising a humate solution, element solution and at least one surfactant. The prepared trace element humate surfactant composition is then dispensed onto the remediation site whereby the trace element humate surfactant composition will reduce the amount of undesirable compounds by promoting growth of native species activity. By promoting native species activity, remediation occurs quickly and environmental impact is minimal.

Synthesis of carbohydrate-based surfactants

Energy Technology Data Exchange (ETDEWEB)

Pemberton, Jeanne E.; Polt, Robin L.; Maier, Raina M.

2016-11-22

The present invention provides carbohydrate-based surfactants and methods for producing the same. Methods for producing carbohydrate-based surfactants include using a glycosylation promoter to link a carbohydrate or its derivative to a hydrophobic compound.

Effect of Source, Surfactant, and Deposition Process on Electronic Properties of Nanotube Arrays

Directory of Open Access Journals (Sweden)

Dheeraj Jain

2011-01-01

Full Text Available The electronic properties of arrays of carbon nanotubes from several different sources differing in the manufacturing process used with a variety of average properties such as length, diameter, and chirality are studied. We used several common surfactants to disperse each of these nanotubes and then deposited them on Si wafers from their aqueous solutions using dielectrophoresis. Transport measurements were performed to compare and determine the effect of different surfactants, deposition processes, and synthesis processes on nanotubes synthesized using CVD, CoMoCAT, laser ablation, and HiPCO.

Small angle neutron scattering study of doxorubicin–surfactant ...

Indian Academy of Sciences (India)

The binding affinity of doxorubicin within the micelle carrier is enhanced through complex formation of drug and anionic surfactant, aerosol OT (AOT). Electrostatic binding of doxorubicin with negatively charged surfactants leads to the formation of hydrophobic drug–surfactant complexes. Surfactant-induced partitioning of ...

DNA compaction by azobenzene-containing surfactant

International Nuclear Information System (INIS)

Zakrevskyy, Yuriy; Kopyshev, Alexey; Lomadze, Nino; Santer, Svetlana; Morozova, Elena; Lysyakova, Ludmila; Kasyanenko, Nina

2011-01-01

We report on the interaction of cationic azobenzene-containing surfactant with DNA investigated by absorption and fluorescence spectroscopy, dynamic light scattering, and atomic force microscopy. The properties of the surfactant can be controlled with light by reversible switching of the azobenzene unit, incorporated into the surfactant tail, between a hydrophobic trans (visible irradiation) and a hydrophilic cis (UV irradiation) configuration. The influence of the trans-cis isomerization of the azobenzene on the compaction process of DNA molecules and the role of both isomers in the formation and colloidal stability of DNA-surfactant complexes is discussed. It is shown that the trans isomer plays a major role in the DNA compaction process. The influence of the cis isomer on the DNA coil configuration is rather small. The construction of a phase diagram of the DNA concentration versus surfactant/DNA charge ratio allows distancing between three major phases: colloidally stable and unstable compacted globules, and extended coil conformation. There is a critical concentration of DNA above which the compacted globules can be hindered from aggregation and precipitation by adding an appropriate amount of the surfactant in the trans configuration. This is because of the compensation of hydrophobicity of the globules with an increasing amount of the surfactant. Below the critical DNA concentration, the compacted globules are colloidally stable and can be reversibly transferred with light to an extended coil state.

Sono-electroanalysis of copper: enhanced detection and determination in the presence of surfactants.

Science.gov (United States)

Hardcastle, Joanna Lorraine; Hignett, Geraldine; Melville, James L; Compton, Richard G

2002-04-01

Surfactant adsorption has been shown to have a passivating effect on the electrode surface during anodic stripping voltammetric measurements. In the present work the feasibility of sono-anodic stripping analysis for the determination of copper in aqueous media contaminated with surfactant has been studied at an unmodified bare glassy carbon electrode. We illustrate the deleterious effect of three common surfactants, sodium dodecyl sulfate (SDS), dodecyl pyridinium chloride (DPC) and Triton-X 100 (TX-100) on conventional electroanalysis. The analogous sono-electroanalytical response was investigated for each surfactant at ultrasound intensities above and below the cavitation threshold. The enhancement in the stripping signal observed is attributed to the increased mass transport due to acoustic streaming and above the cavitation threshold the intensity of cavitational events is significantly increased leading to shearing of adsorbed surfactant molecules from the surface. As a result accurate analyses for SDS concentrations up to 100 ppm are possible, with analytical signals visible in solutions of SDS and TX-100 of 1000 ppm. Analysis is reported in high concentration of surfactant with use of sono-solvent double extraction. The power of this technique is clearly illustrated by the ability to obtain accurate measurements of copper concentration from starting solutions containing 1000 ppm SDS or TX-100. This was also exemplified by analysis of the low concentration 0.3 microM Cu(II) solution giving a percentage recovery of 94% in the presence of 1000 ppm SDS or TX-100.

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

Science.gov (United States)

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

2014-11-01

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

Interactions between Streptomyces coelicolor and Bacillus subtilis: Role of surfactants in raising aerial structures.

Science.gov (United States)

Straight, Paul D; Willey, Joanne M; Kolter, Roberto

2006-07-01

Using mixed-species cultures, we have undertaken a study of interactions between two common spore-forming soil bacteria, Bacillus subtilis and Streptomyces coelicolor. Our experiments demonstrate that the development of aerial hyphae and spores by S. coelicolor is inhibited by surfactin, a lipopeptide surfactant produced by B. subtilis. Current models of aerial development by sporulating bacteria and fungi postulate a role for surfactants in reducing surface tension at air-liquid interfaces, thereby removing the major barrier to aerial growth. S. coelicolor produces SapB, an amphipathic peptide that is surface active and required for aerial growth on certain media. Loss of aerial hyphae in developmental mutants can be rescued by addition of purified SapB. While a surfactant from a fungus can substitute for SapB in a mutant that lacks aerial hyphae, not all surfactants have this effect. We show that surfactin is required for formation of aerial structures on the surface of B. subtilis colonies. However, in contrast to this positive role, our experiments reveal that surfactin acts antagonistically by arresting S. coelicolor aerial development and causing altered expression of developmental genes. Our observations support the idea that surfactants function specifically for a given organism regardless of their shared ability to reduce surface tension. Production of surfactants with antagonistic activity could provide a powerful competitive advantage during surface colonization and in competition for resources.

Binding of cationic surfactants to humic substances

NARCIS (Netherlands)

Ishiguro, M.; Tan, W.; Koopal, L.K.

2007-01-01

Commercial surfactants are introduced into the environment either through waste products or site-specific contamination. The amphiphilic nature of both surfactants and humic substances (HS) leads to their mutual attraction especially when surfactant and HS are oppositely charged. Binding of the

Survey shows large differences between the Nordic countries in the use of less invasive surfactant administration

DEFF Research Database (Denmark)

Jonsson, Baldvin; Andersson, Sture; Björklund, Lars J

2017-01-01

AIM: Less invasive surfactant administration (LISA), namely surfactant instillation through a thin catheter in the trachea during spontaneous breathing, is increasingly used for premature infants. We surveyed the use of this technique in the Nordic countries in autumn 2015. METHODS: A link to a web......-based survey of surfactant administration methods was emailed to the directors of all neonatal units in the Nordic Region, apart from Finland, where only the five university-based departments were invited. RESULTS: Of the 73 units (85%) who responded, 23 (32%) said that they used LISA. The country rates were......%. The main reasons for not using LISA were lack of familiarity with the technique (61%), no perceived benefit over other methods (22%) and concerns about patient discomfort (26%). CONCLUSION: Less invasive surfactant administration was used in 32% of Nordic neonatal units, most commonly in level three units...

Transport of Fluorescently Labeled Hydroxyapatite Nanoparticles in Saturated Granular Media at Environmentally Relevant Concentrations of Surfactants

Science.gov (United States)

Little is known about the mobility of engineered nanoparticles (ENPs) in granular media at environmentally relevant concentration of surfactant, which represents a critical knowledge gap in employing ENPs for in-situ remediation of contaminated groundwater. In this study, transpo...

Biomimetic oligosaccharide and peptide surfactant polymers designed for cardiovascular biomaterials

Science.gov (United States)

Ruegsegger, Mark Andrew

A common problem associated with cardiovascular devices is surface induced thrombosis initiated by the rapid, non-specific adsorption of plasma proteins onto the biomaterial surface. Control of the initial protein adsorption is crucial to achieve the desired longevity of the implanted biomaterial. The cell membrane glycocalyx acts as a non-thrombogenic interface through passive (dense oligosaccharide structures) and active (ligand/receptor interactions) mechanisms. This thesis is designed to investigate biomimicry of the cell glycocalyx to minimize non-specific protein adsorption and promote specific ligand/receptor interactions. Biomimetic macromolecules were designed through the molecular-scale engineering of polymer surfactants, utilizing a poly(vinyl amine) (PVAm) backbone to which hydrophilic (dextran, maltose, peptide) and hydrophobic alkyl (hexanoyl or hexanal) chains are simultaneously attached. The structure was controlled through the molar feed ratio of hydrophobic-to-hydrophilic groups, which also provided control of the solution and surface-active properties. To mimic passive properties, a series of oligomaltose surfactants were synthesized with increasing saccharide length (n = 2, 7, 15 where n is number of glucose units) to investigate the effect of coating height on protein adsorption. The surfactants were characterized by infra red (IR) and nuclear magnetic resonance (NMR) spectroscopies for structural properties and atomic force microscopy (AFM) and contact angle goniometry for surface activity. Protein adsorption under dynamic flow (5 dyn/cm2) was reduced by 85%--95% over the bare hydrophobic substrate; platelet adhesion dropped by ˜80% compared to glass. Peptide ligands were incorporated into the oligosaccharide surfactant to promote functional activity of the passive coating. The surfactants were synthesized to contain 0%, 25%, 50%, 75%, and 100% peptide ligand density and were stable on hydrophobic surfaces. The peptide surface density was

Effect of dielectric fluid with surfactant and graphite powder on Electrical Discharge Machining of titanium alloy using Taguchi method

Directory of Open Access Journals (Sweden)

Murahari Kolli

2015-12-01

Full Text Available In this paper, Taguchi method was employed to optimize the surfactant and graphite powder concentration in dielectric fluid for the machining of Ti-6Al-4V using Electrical Discharge Machining (EDM. The process parameters such as discharge current, surfactant concentration and powder concentration were changed to explore their effects on Material Removal Rate (MRR, Surface Roughness (SR, Tool wear rate (TWR and Recast Layer Thickness (RLT. Detailed analysis of structural features of machined surface was carried out using Scanning Electron Microscope (SEM to observe the influence of surfactant and graphite powder on the machining process. It was observed from the experimental results that the graphite powder and surfactant added dielectric fluid significantly improved the MRR, reduces the SR, TWR and RLT at various conditions. Analysis of Variance (ANOVA and F-test of experimental data values related to the important process parameters of EDM revealed that discharge current and surfactant concentration has more percentage of contribution on the MRR and TWR whereas the SR, and RLT were found to be affected greatly by the discharge current and graphite powder concentration.

Enhanced In Situ Chemical Oxidation Using Surfactants and Shear Thinning Fluids

Science.gov (United States)

Hauswirth, S.; Sadeghi, S.; Cerda, C. C.; Espinoza, I.; Schultz, P. B.; Miller, C. T.

2017-12-01

In situ chemical oxidation (ISCO) is an attractive approach for the remediation of recalcitrant contaminants, due to the fact that target compounds are degraded in place, precluding the need for ex situ treatment or disposal. However, field applications of ISCO approaches have been plagued by "rebound" of contaminant concentrations in groundwater weeks to months after treatment. The cause of rebound at a given site may vary, but is typically associated with back-diffusion from finer grained, low permeability units or the presence of non-aqueous phase liquids (NAPLs) that are incompletely degraded during treatment. Modifications to traditional ISCO methods have been proposed to overcome these challenges, including the use of shear-thinning polymers to improve delivery of oxidants to low permeability units and the addition of surfactants to improve dissolution of contaminants from NAPLs. In this work, we investigate the application of these approaches to the oxidation of manufactured gas plant (MGP) tars—NAPLs composed primarily of polycyclic aromatic hydrocarbons (PAHs). We conducted experiments to determine the mutual impact of each chemical component on the physical and chemical properties of the overall system. Specifically, experiments were designed to: determine the kinetics and overall effectiveness of contaminant-oxidant reactions for multiple oxidant-activator combinations; screen several common surfactants in terms of their ability to increase MGP tar solubility and their compatibility with oxidant systems; measure the impact of oxidants and surfactants on the rheology of several common polymer additives; and assess the effect of surfactants and polymers on the consumption of oxidants/activators and on the kinetics of contaminant-oxidant reactions. The results of this work provide insight into the chemical and physical mechanisms associated with enhanced ISCO approaches and an improved basis with which to model and design ISCO applications at both the lab

Surfactants tailored by the class Actinobacteria

Science.gov (United States)

Kügler, Johannes H.; Le Roes-Hill, Marilize; Syldatk, Christoph; Hausmann, Rudolf

2015-01-01

Globally the change towards the establishment of a bio-based economy has resulted in an increased need for bio-based applications. This, in turn, has served as a driving force for the discovery and application of novel biosurfactants. The class Actinobacteria represents a vast group of microorganisms with the ability to produce a diverse range of secondary metabolites, including surfactants. Understanding the extensive nature of the biosurfactants produced by actinobacterial strains can assist in finding novel biosurfactants with new potential applications. This review therefore presents a comprehensive overview of the knowledge available on actinobacterial surfactants, the chemical structures that have been completely or partly elucidated, as well as the identity of the biosurfactant-producing strains. Producer strains of not yet elucidated compounds are discussed, as well as the original habitats of all the producer strains, which seems to indicate that biosurfactant production is environmentally driven. Methodology applied in the isolation, purification and structural elucidation of the different types of surface active compounds, as well as surfactant activity tests, are also discussed. Overall, actinobacterial surfactants can be summarized to include the dominantly occurring trehalose-comprising surfactants, other non-trehalose containing glycolipids, lipopeptides and the more rare actinobacterial surfactants. The lack of structural information on a large proportion of actinobacterial surfactants should be considered as a driving force to further explore the abundance and diversity of these compounds. This would allow for a better understanding of actinobacterial surface active compounds and their potential for biotechnological application. PMID:25852670

Surfactants tailored by the class Actinobacteria

Directory of Open Access Journals (Sweden)

Johannes H Kügler

2015-03-01

Full Text Available Gloablly, the drive towards the establishment of a bio-based economy has resulted in an increased need for bio-based applications. This, in turn, has served as a driving force for the discovery and application of novel biosurfactants. The class Actinobacteria represents a vast group of microorganisms with the ability to produce a diverse range of secondary metabolites, including surfactants. Understanding the extensive nature of the biosurfactants produced by actinobacterial strains can assist in finding novel biosurfactants with new potential applications. This review therefore presents a comprehensive overview of the knowledge available on actinobacterial surfactants, the chemical structures that have been completely or partly elucidated, as well as the identity of the biosurfactant-producing strains. Producer strains of not yet elucidated compounds are discussed, as well as the original habitats of all the producer strains, which seems to indicate that biosurfactant production is environmentally driven. Methodology applied in the isolation, purification and structural elucidation of the different types of surface active compounds, as well as surfactant activity tests, are also discussed. Overall, actinobacterial surfactants can be summarized to include the dominantly occurring trehalose-comprising surfactants, other non-trehalose containing glycolipids, lipopeptides and the more rare actinobacterial surfactants. The lack of structural information on a large proportion of actinobacterial surfactants should be considered as a driving force to further explore the abundance and diversity of these compounds. This would allow for a better understanding of actinobacterial surface active compounds and their potential for biotechnological application.

Preparation of mesoporous nanofibers by vapor phase synthesis: control of mesopore structures with the aid of co-surfactants

International Nuclear Information System (INIS)

Min, Sa Hoon; Jang, Jyongsik; Lee, Kyung Jin; Bae, Joonwon

2013-01-01

Mesoporous nanofibers (MSNFs) can be fabricated in the pores of anodic aluminum oxide (AAO) membrane using diverse methods. Among them vapor phase synthesis (VPS) provides several advantages over sol–gel or evaporation-induced self-assembly (EISA) based methods. One powerful advantage is that we can employ multiple surfactants as structural directing agents (SDAs) simultaneously. By adopting diverse pairs of SDAs, we can control the mesopore structures, i.e. pore size, surface area, and even the morphology of mesostructures. Here, we used F127 as a main SDA, which is relatively robust (thus, difficult to change the mesopore structures), and added a series of cationic co-surfactants to observe the systematical changes in their mesostructure with respect to the chain length of the co-surfactant. (paper)

Preparation of mesoporous nanofibers by vapor phase synthesis: control of mesopore structures with the aid of co-surfactants

Energy Technology Data Exchange (ETDEWEB)

Min, Sa Hoon; Jang, Jyongsik; Lee, Kyung Jin [School of Chemical and Biological Engineering, College of Engineering, Seoul National University, Shinlimdong 56-1, Seoul, 151-742 (Korea, Republic of); Bae, Joonwon [Department of Applied Chemistry, Dongduk Women' s University, Seoul 136-714 (Korea, Republic of)

2013-06-28

Mesoporous nanofibers (MSNFs) can be fabricated in the pores of anodic aluminum oxide (AAO) membrane using diverse methods. Among them vapor phase synthesis (VPS) provides several advantages over sol-gel or evaporation-induced self-assembly (EISA) based methods. One powerful advantage is that we can employ multiple surfactants as structural directing agents (SDAs) simultaneously. By adopting diverse pairs of SDAs, we can control the mesopore structures, i.e. pore size, surface area, and even the morphology of mesostructures. Here, we used F127 as a main SDA, which is relatively robust (thus, difficult to change the mesopore structures), and added a series of cationic co-surfactants to observe the systematical changes in their mesostructure with respect to the chain length of the co-surfactant. (paper)

Preparation of mesoporous nanofibers by vapor phase synthesis: control of mesopore structures with the aid of co-surfactants

Science.gov (United States)

Min, Sa Hoon; Bae, Joonwon; Jang, Jyongsik; Lee, Kyung Jin

2013-06-01

Mesoporous nanofibers (MSNFs) can be fabricated in the pores of anodic aluminum oxide (AAO) membrane using diverse methods. Among them vapor phase synthesis (VPS) provides several advantages over sol-gel or evaporation-induced self-assembly (EISA) based methods. One powerful advantage is that we can employ multiple surfactants as structural directing agents (SDAs) simultaneously. By adopting diverse pairs of SDAs, we can control the mesopore structures, i.e. pore size, surface area, and even the morphology of mesostructures. Here, we used F127 as a main SDA, which is relatively robust (thus, difficult to change the mesopore structures), and added a series of cationic co-surfactants to observe the systematical changes in their mesostructure with respect to the chain length of the co-surfactant.

In vitro surfactant structure-toxicity relationships: implications for surfactant use in sexually transmitted infection prophylaxis and contraception.

Directory of Open Access Journals (Sweden)

Ângela S Inácio

Full Text Available BACKGROUND: The need for woman-controlled, cheap, safe, effective, easy-to-use and easy-to-store topical applications for prophylaxis against sexually transmitted infections (STIs makes surfactant-containing formulations an interesting option that requires a more fundamental knowledge concerning surfactant toxicology and structure-activity relationships. METHODOLOGY/PRINCIPAL FINDINGS: We report in vitro effects of surfactant concentration, exposure time and structure on the viability of mammalian cell types typically encountered in the vagina, namely, fully polarized and confluent epithelial cells, confluent but non-polarized epithelial-like cells, dendritic cells, and human sperm. Representatives of the different families of commercially available surfactants--nonionic (Triton X-100 and monolaurin, zwitterionic (DDPS, anionic (SDS, and cationic (C(nTAB (n = 10 to 16, C(12PB, and C(12BZK--were examined. Triton X-100, monolaurin, DDPS and SDS were toxic to all cell types at concentrations around their critical micelle concentration (CMC suggesting a non-selective mode of action involving cell membrane destabilization and/or destruction. All cationic surfactants were toxic at concentrations far below their CMC and showed significant differences in their toxicity toward polarized as compared with non-polarized cells. Their toxicity was also dependent on the chemical nature of the polar head group. Our results suggest an intracellular locus of action for cationic surfactants and show that their structure-activity relationships could be profitably exploited for STI prophylaxis in vaginal gel formulations. The therapeutic indices comparing polarized epithelial cell toxicity to sperm toxicity for all surfactants examined, except C(12PB and C(12BZK, does not justify their use as contraceptive agents. C(12PB and C(12BZK are shown to have a narrow therapeutic index recommending caution in their use in contraceptive formulations. CONCLUSIONS

Next Generation Surfactants for Improved Chemical Flooding Technology

Energy Technology Data Exchange (ETDEWEB)

Laura Wesson; Prapas Lohateeraparp; Jeffrey Harwell; Bor-Jier Shiau

2012-05-31

The principle objective of this project was to characterize and test current and next generation high performance surfactants for improved chemical flooding technology, focused on reservoirs in the Pennsylvanian-aged (Penn) sands. In order to meet this objective the characteristic curvatures (Cc) of twenty-eight anionic surfactants selected for evaluation for use in chemical flooding formulations were determined. The Cc values ranged from -6.90 to 2.55 with the majority having negative values. Crude oil samples from nine Penn sand reservoirs were analyzed for several properties pertinent to surfactant formulation for EOR application. These properties included equivalent alkane carbon numbers, total acid numbers, and viscosity. The brine samples from these same reservoirs were analyzed for several cations and for total dissolved solids. Surfactant formulations were successfully developed for eight reservoirs by the end of the project period. These formulations were comprised of a tertiary mixture of anionic surfactants. The identities of these surfactants are considered proprietary, but suffice to say the surfactants in each mixture were comprised of varying chemical structures. In addition to the successful development of surfactant formulations for EOR, there were also two successful single-well field tests conducted. There are many aspects that must be considered in the development and implementation of effective surfactant formulations. Taking into account these other aspects, there were four additional studies conducted during this project. These studies focused on the effect of the stability of surfactant formulations in the presence of polymers with an associated examination of polymer rheology, the effect of the presence of iron complexes in the brine on surfactant stability, the potential use of sacrificial agents in order to minimize the loss of surfactant to adsorption, and the effect of electrolytes on surfactant adsorption. In these last four studies

The Molecular Era of Surfactant Biology

OpenAIRE

Whitsett, Jeffrey A.

2014-01-01

Advances in the physiology, biochemistry, molecular and cell biology of the pulmonary surfactant system transformed the clinical care and outcome of preterm infants with respiratory distress syndrome. The molecular era of surfactant biology provided genetic insights into the pathogenesis of pulmonary disorders, previously termed “idiopathic” that affect newborn infants, children and adults. Knowledge related to the structure and function of the surfactant proteins and their roles in alveolar ...

Nanoparticle-enabled delivery of surfactants in porous media.

Science.gov (United States)

Nourafkan, Ehsan; Hu, Zhongliang; Wen, Dongsheng

2018-06-01

The adsorption of surfactants on the reservoir rocks surface is a serious issue in many energy and environment related areas. Learning from the concept of drug delivery in the nano-medicine field, this work proposes and validates the concept of using nanoparticles to deliver a mixture of surfactants into a porous medium. TiO 2 nanoparticles (NPs) are used as carriers for a blend of surfactants mixtures including anionic alkyl aryl sulfonic acid (AAS) and nonionic alcohol ethoxylated (EA) at the optimum salinity and composition conditions. The transport of NPs through a core sample of crushed sandstone grains and the adsorption of surfactants are evaluated. By using TiO 2 NPs, the adsorption of surfactant molecules can be significantly reduced, i.e. half of the initial adsorption value. The level of surfactant adsorption reduction is related to the NPs transport capability through the porous medium. An application study shows that comparing to surfactant flooding alone, the total oil recovery can be increased by 7.81% of original oil in place (OOIP) by using nanoparticle bonded surfactants. Such work shows the promise of NP as an effective surfactant carrier for sandstone reservoirs, which could have many potential applications in enhanced oil recovery (EOR) and environmental remediation. Copyright © 2018 Elsevier Inc. All rights reserved.

Comparison of rSP-C surfactant with natural and synthetic surfactants after late treatment in a rat model of the acute respiratory distress syndrome

Science.gov (United States)

Häfner, Dietrich; Germann, Paul-Georg; Hauschke, Dieter

1998-01-01

In a previous paper we showed that an SP-C containing surfactant preparation has similar activity as bovine-derived surfactants in a rat lung lavage model of the adult respiratory distress syndrome. In this study surfactant was given ten minutes after the last lavage (early treatment). In the present investigation we were interested how different surfactant preparations behave when they are administered 1 h after the last lavage (late treatment). Four protein containing surfactants (rSP-C surfactant, bLES, Infasurf and Survanta) were compared with three protein-free surfactants (ALEC, Exosurf and the phospholipid (PL) mixture of the rSP-C surfactant termed PL surfactant) with respect to their ability to improve gas exchange in this more stringent model when surfactant is given one hour after the last lavage. For better comparison of the surfactants the doses were related to phospholipids. The surfactants were given at doses of 25, 50 and 100 mg kg−1 body weight. The surfactants were compared to an untreated control group that was only ventilated for the whole experimental period. Tracheotomized rats (8–12 per dose and surfactant) were pressure-controlled ventilated (Siemens Servo Ventilator 900C) with 100% oxygen at a respiratory rate of 30 breaths min−1, inspiration expiration ratio of 1 : 2, peak inspiratory pressure of 28 cmH2O at positive endexpiratory pressure (PEEP) of 8 cmH2O. Animals were ventilated for one hour after the last lavage and thereafter the surfactants were intratracheally instilled. During the whole experimental period the ventilation was not changed. Partial arterial oxygen pressures (PaO2, mmHg) at 30 min and 120 min after treatment were used for statistical comparison. All protein containing surfactants caused a dose-dependent increase of the reduced PaO2 values at 30 min after treatment. The protein-free surfactants showed only weak dose-dependent increase in PaO2 values at this time. This difference between the

Surfactant modified clays’ consistency limits and contact angles

Directory of Open Access Journals (Sweden)

S Akbulut

2012-07-01

Full Text Available This study was aimed at preparing a surfactant modified clay (SMC and researching the effect of surfactants on clays' contact angles and consistency limits; clay was thus modified by surfactants formodifying their engineering properties. Seven surfactants (trimethylglycine, hydroxyethylcellulose  octyl phenol ethoxylate, linear alkylbenzene sulfonic acid, sodium lauryl ether sulfate, cetyl trimethylammonium chloride and quaternised ethoxylated fatty amine were used as surfactants in this study. The experimental results indicated that SMC consistency limits (liquid and plastic limits changedsignificantly compared to those of natural clay. Plasticity index and liquid limit (PI-LL values representing soil class approached the A-line when zwitterion, nonionic, and anionic surfactant percentageincreased. However, cationic SMC became transformed from CH (high plasticity clay to MH (high plasticity silt class soils, according to the unified soil classification system (USCS. Clay modifiedwith cationic and anionic surfactants gave higher and lower contact angles than natural clay, respectively.

Probing dynamics and mechanism of exchange process of quaternary ammonium dimeric surfactants, 14-s-14, in the presence of conventional surfactants.

Science.gov (United States)

Liu, Jun; Jiang, Yan; Chen, Hong; Mao, Shi Zhen; Du, You Ru; Liu, Mai Li

2012-12-27

In this Article, we investigated effects of different types of conventional surfactants on exchange dynamics of quaternary ammonium dimeric surfactants, with chemical formula C(14)H(29)N(+)(CH(3))(2)- (CH(2))(s)-N(+)(CH(3))(2)C(14)H(29)·2Br(-), or 14-s-14 for short. Two nonionic surfactants, TritonX-100 (TX-100) and polyethylene glycol (23) laurylether (Brij-35), and one cationic surfactant, n-tetradecyltrimethyl ammonium bromide (TTAB), and one ionic surfactant, sodium dodecyl sulfate (SDS) were chosen as typical conventional surfactants. Exchange rates of 14-s-14 (s = 2, 3, and 4) between the micelle form and monomer in solution were detected by two NMR methods: one-dimensional (1D) line shape analysis and two-dimensional (2D) exchange spectroscopy (EXSY). Results show that the nonionic surfactants (TX-100 and Brij-35), the cationic surfactant (TTAB), and the ionic surfactant (SDS) respectively accelerated, barely influenced, and slowed the exchange rate of 14-s-14. The effect mechanism was investigated by the self-diffusion experiment, relaxation time measurements (T(2)/T(1)), the fluorescence experiment (I(1)/I(3)) and observed chemical shift variations. Results reveal that, nonionic conventional surfactants (TX-100 and Brij-35) loosened the molecule arrangement and decreased hydrophobic interactions in the micelle, and thus accelerated the exchange rate of 14-s-14. The cationic conventional surfactant (TTAB) barely changed the molecule arrangement and thus barely influenced the exchange rate of 14-s-14. The ionic conventional surfactant (SDS) introduced the electrostatic attraction effect, tightened the molecule arrangement, and increased hydrophobic interactions in the micelle, and thus slowed down the exchange rate of 14-s-14. Additionally, the two-step exchange mechanism of 14-s-14 in the mixed solution was revealed through interesting variation tendencies of exchange rates of 14-s-14.

In situ X-ray polymerization: from swollen lamellae to polymer-surfactant complexes.

Science.gov (United States)

Agzenai, Yahya; Lindman, Björn; Alfredsson, Viveka; Topgaard, Daniel; Renamayor, Carmen S; Pacios, Isabel E

2014-01-30

The influence of the monomer diallyldimethylammonium chloride (D) on the lamellar liquid crystal formed by the anionic surfactant aerosol OT (AOT) and water is investigated, determining the lamellar spacings by SAXS and the quadrupolar splittings by deuterium NMR, as a function of the D or AOT concentrations. The cationic monomer D induces a destabilization of the AOT lamellar structure such that, at a critical concentration higher than 5 wt %, macroscopic phase separation takes place. When the monomer, which is dissolved in the AOT lamellae, is polymerized in situ by X-ray initiation, a new collapsed lamellar phase appears, corresponding to the complexation of the surfactant with the resulting polymer. A theoretical model is employed to analyze the variation of the interactions between the AOT bilayers and the stability of the lamellar structure.

Effects of Surfactant on Geotechnical Characteristics of Silty Soil

International Nuclear Information System (INIS)

Rahman, Z.A.; Sahibin, A.R.; Lihan, T.; Idris, W.M.R.; Sakina, M.

2013-01-01

Surfactants are often used as a cleaning agent for restoration of oil-contaminated soil. However the effect of surfactant on the geotechnical properties of soil is not clearly understood. In this study, the effects of surfactant on silty soil were investigated for consistency index, compaction, permeability and shear strength. Sodium dodecyl sulfate (SDS) was used in this study to prepare the surfactant-treated soil. Our results showed that the soil with added surfactant exhibited a decrease in liquid and plastic limit values. Maximum dry densities increased and optimum moisture contents decreased as contents of added surfactant were increased. The presence of surfactant assists the soil to achieve maximum density at lower water content. The addition of surfactant decreased the permeability of soil from 6.29 x 10 -4 to 1.15 x 10 -4 ms -1 . The shear strength of soil with added surfactant was examined using the undrained unconsolidated triaxial tests. The results showed that the undrained shear strength, Cu was significantly affected, decreased from 319 kPa to 50 kPa for soil with 20 % of added surfactant. The results of this study showed that the presence of surfactant in soil can modify the mechanical behaviour of the soil. (author)

Surfactant-enhanced control of track-etch pore morphology

International Nuclear Information System (INIS)

Apel', P.Yu.; Blonskaya, I.V.; Didyk, A.Yu.; Dmitriev, S.N.; Orelovich, O.L.; Samojlova, L.I.; Vutsadakis, V.A.; Root, D.

2000-01-01

The influence of surfactants on the process of chemical development of ion tracks in polymers is studied. Based on the experimental data, a mechanism of the surfactant effect on the track-etch pore morphology is proposed. In the beginning of etching the surfactant is adsorbed on the surface and creates a layer that is quasi-solid and partially protects the surface from the etching agent. However, some etchant molecules diffuse through the barrier and react with the polymer surface. This results in the formation of a small hole at the entrance to the ion track. After the hole has attained a few annometers in diameter, the surfactant molecules penetrate into the track and cover its walls. Further diffusion of the surfactant into the growing pore is hindered. The adsorbed surfactant layer is not permeable for large molecules. In contrast, small alkali molecules and water molecules diffuse into the track and provide the etching process enlarging the pore. At this stage the transport of the surfactant into the pore channel can proceed only due to the lateral diffusion in the adsorbed layer. The volume inside the pore is free of surfactant molecules and grows at a higher rate than pore entrance. After a more prolonged etching the bottle-like (or 'cigar-like') pore channels are formed. The bottle-like shape of the pore channels depends on the etching conditions such as alkali and surfactant concentration, temperature, and type of the surfactant. The use of surfactants enables one to produce track-etch membranes with improved flow rate characteristics compared with those having cylindrical pores with the same nominal pore diameters

Open lung ventilation preserves the response to delayed surfactant treatment in surfactant-deficient newborn piglets

NARCIS (Netherlands)

van Veenendaal, Mariëtte B.; van Kaam, Anton H.; Haitsma, Jack J.; Lutter, René; Lachmann, Burkhard

2006-01-01

OBJECTIVE: Delayed surfactant treatment (>2 hrs after birth) is less effective than early treatment in conventionally ventilated preterm infants with respiratory distress syndrome. The objective of this study was to evaluate if this time-dependent efficacy of surfactant treatment is also present

Influence of surfactants in forced dynamic dewetting.

Science.gov (United States)

Henrich, Franziska; Fell, Daniela; Truszkowska, Dorota; Weirich, Marcel; Anyfantakis, Manos; Nguyen, Thi-Huong; Wagner, Manfred; Auernhammer, Günter K; Butt, Hans-Jürgen

2016-09-20

In this work we show that the forced dynamic dewetting of surfactant solutions depends sensitively on the surfactant concentration. To measure this effect, a hydrophobic rotating cylinder was horizontally half immersed in aqueous surfactant solutions. Dynamic contact angles were measured optically by extrapolating the contour of the meniscus to the contact line. Anionic (sodium 1-decanesulfonate, S-1DeS), cationic (cetyl trimethylammonium bromide, CTAB) and nonionic surfactants (C 4 E 1 , C 8 E 3 and C 12 E 5 ) with critical micelle concentrations (CMCs) spanning four orders of magnitude were used. The receding contact angle in water decreased with increasing velocity. This decrease was strongly enhanced when adding surfactant, even at surfactant concentrations of 10% of the critical micelle concentration. Plots of the receding contact angle-versus-velocity almost superimpose when being plotted at the same relative concentration (concentration/CMC). Thus the rescaled concentration is the dominating property for dynamic dewetting. The charge of the surfactants did not play a role, thus excluding electrostatic effects. The change in contact angle can be interpreted by local surface tension gradients, i.e. Marangoni stresses, close to the three-phase contact line. The decrease of dynamic contact angles with velocity follows two regimes. Despite the existence of Marangoni stresses close to the contact line, for a dewetting velocity above 1-10 mm s -1 the hydrodynamic theory is able to describe the experimental results for all surfactant concentrations. At slower velocities an additional steep decrease of the contact angle with velocity was observed. Particle tracking velocimetry showed that the flow profiles do not differ with and without surfactant on a scales >100 μm.

Dimeric Surfactants: Promising Ingredients of Cosmetics and Toiletries

Directory of Open Access Journals (Sweden)

Naveen Kumar

2013-11-01

Full Text Available Surfactants are an essential ingredient for cosmetic, toiletries and personal care products for enhancing their performance. Dimeric surfactants demonstrate superiority compared to conventional surfactants in all areas of application. Dimeric surfactants are extremely promising for utilization in various cosmetic formulations viz. shampoo, lotions, creams, conditioners etc. These surfactants possess extremely unique surface properties viz. lower surface tension, unique micellization, low critical micelle concentration (CMC and antimicrobial activity, higher solubilization etc. Dimerics enhance the performances of cosmetics in an extraordinary manner and provide eco-friendly preparations for human epidermis.

Structural study of surfactant-dependent interaction with protein

Energy Technology Data Exchange (ETDEWEB)

Mehan, Sumit; Aswal, Vinod K., E-mail: vkaswal@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kohlbrecher, Joachim [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 PSI Villigen (Switzerland)

2015-06-24

Small-angle neutron scattering (SANS) has been used to study the complex structure of anionic BSA protein with three different (cationic DTAB, anionic SDS and non-ionic C12E10) surfactants. These systems form very different surfactant-dependent complexes. We show that the structure of protein-surfactant complex is initiated by the site-specific electrostatic interaction between the components, followed by the hydrophobic interaction at high surfactant concentrations. It is also found that hydrophobic interaction is preferred over the electrostatic interaction in deciding the resultant structure of protein-surfactant complexes.

Effect of double-tailed surfactant architecture on the conformation, self-assembly, and processing in polypeptide-surfactant complexes.

Science.gov (United States)

Junnila, Susanna; Hanski, Sirkku; Oakley, Richard J; Nummelin, Sami; Ruokolainen, Janne; Faul, Charl F J; Ikkala, Olli

2009-10-12

This work describes the solid-state conformational and structural properties of self-assembled polypeptide-surfactant complexes with double-tailed surfactants. Poly(L-lysine) was complexed with three dialkyl esters of phosphoric acid (i.e., phosphodiester surfactants), where the surfactant tail branching and length was varied to tune the supramolecular architecture in a facile way. After complexation with the branched surfactant bis(2-ethylhexyl) phosphate in an aqueous solution, the polypeptide chains adopted an alpha-helical conformation. These rod-like helices self-assembled into cylindrical phases with the amorphous alkyl tails pointing outward. In complexes with dioctyl phosphate and didodecyl phosphate, which have two linear n-octyl or n-dodecyl tails, respectively, the polypeptide formed antiparallel beta-sheets separated by alkyl layers, resulting in well-ordered lamellar self-assemblies. By heating, it was possible to trigger a partial opening of the beta-sheets and disruption of the lamellar phase. After repeated heating/cooling, all of these complexes also showed a glass transition between 37 and 50 degrees C. Organic solvent treatment and plasticization by overstoichiometric amount of surfactant led to structure modification in poly(L-lysine)-dioctyl phosphate complexes, PLL(diC8)(x) (x = 1.0-3.0). Here, the alpha-helical PLL is surrounded by the surfactants and these bottle-brush-like chains self-assemble in a hexagonal cylindrical morphology. As x is increased, the materials are clearly plasticized and the degree of ordering is improved: The stiff alpha-helical backbones in a softened surfactant matrix give rise to thermotropic liquid-crystalline phases. The complexes were examined by Fourier transform infrared spectroscopy, small- and wide-angle X-ray scattering, transmission electron microscopy, differential scanning calorimetry, polarized optical microscopy, and circular dichroism.

The Biophysical Function of Pulmonary Surfactant

OpenAIRE

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

2008-01-01

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....

Roentgenographic findings in hyaline membrane disease treated with exogenous surfactant: comparison with control group

International Nuclear Information System (INIS)

Lee, Sun Kyoung; Lim, Chae Ha; Lim, Woo Young; Kim, Young Sook; Byen, Ju Nam; Oh, Jae Hee; Kim, Young Chul

1997-01-01

To compare, with the use of chest radiographic findings, improvement and complications in newborns treated with exogenous surfactant for hyaline membrane disease (HMD), and an untreated control group. Thirty-six patients with HMD were randomly assigned to a control group (n=18) or surfactant treated group (n=18). As part of an initial evaluation of their pulmonary status, we then performed a retrospective statistical analysis of chest radiographic findings obtained in exogenous surfactant treated and untreated infants within the first 90 minutes of life. Subsequent examinations were performed at less than 24 hours of age. Chest radiograph before treatment showed no significant differences between the two groups, but significant improvement was noted in the surfactant treated group, in contrast to the control group. The most common chest radiographic finding after surfactant administration was uniform (n=15) or disproportionate (n=2) improvement of pulmonary aeration. Patent ductus arteriosus developed in three treated neonates and in four cases in the control group. Air leak occurred in three cases in the treated group and in five cases in the control group. In one treated patient pulmonary hemorrhage developed and intracranial hemorrhage occurred in three treated neonates and in four cases in the control group. Bronchopulmonary dysplasia was developed in 6 cases of treated group and 3 cases of control group. A chest radiograph is considered to be helpful in the evaluation of improvement and complications of HMD in infants treated with surfactant

Neonatal varicella pneumonia, surfactant replacement therapy

Directory of Open Access Journals (Sweden)

Mousa Ahmadpour-kacho

2015-12-01

Full Text Available Background: Chickenpox is a very contagious viral disease that caused by varicella-zoster virus, which appears in the first week of life secondary to transplacental transmission of infection from the affected mother. When mother catches the disease five days before and up to two days after the delivery, the chance of varicella in neonate in first week of life is 17%. A generalized papulovesicular lesion is the most common clinical feature. Respiratory involvement may lead to giant cell pneumonia and respiratory failure. The mortality rate is up to 30% in the case of no treatment, often due to pneumonia. Treatment includes hospitalization, isolation and administration of intravenous acyclovir. The aim of this case report is to introduce the exogenous surfactant replacement therapy after intubation and mechanical ventilation for respiratory failure in neonatal chickenpox pneumonia and respiratory distress. Case Presentation: A seven-day-old neonate boy was admitted to the Neonatal Intensive Care Unit at Amirkola Children’s Hospital, Babol, north of Iran, with generalized papulovesicular lesions and respiratory distress. His mother has had a history of Varicella 4 days before delivery. He was isolated and given supportive care, intravenous acyclovir and antibiotics. On the second day, he was intubated and connected to mechanical ventilator due to severe pneumonia and respiratory failure. Because of sever pulmonary involvement evidenced by Chest X-Ray and high ventilators set-up requirement, intratracheal surfactant was administered in two doses separated by 12 hours. He was discharged after 14 days without any complication with good general condition. Conclusion: Exogenous surfactant replacement therapy can be useful as an adjunctive therapy for the treatment of respiratory failure due to neonatal chickenpox.

Hydrophilic interaction liquid chromatography-tandem mass spectrometry quantitative method for the cellular analysis of varying structures of gemini surfactants designed as nanomaterial drug carriers.

Science.gov (United States)

Donkuru, McDonald; Michel, Deborah; Awad, Hanan; Katselis, George; El-Aneed, Anas

2016-05-13

Diquaternary gemini surfactants have successfully been used to form lipid-based nanoparticles that are able to compact, protect, and deliver genetic materials into cells. However, what happens to the gemini surfactants after they have released their therapeutic cargo is unknown. Such knowledge is critical to assess the quality, safety, and efficacy of gemini surfactant nanoparticles. We have developed a simple and rapid liquid chromatography electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method for the quantitative determination of various structures of gemini surfactants in cells. Hydrophilic interaction liquid chromatography (HILIC) was employed allowing for a short simple isocratic run of only 4min. The lower limit of detection (LLOD) was 3ng/mL. The method was valid to 18 structures of gemini surfactants belonging to two different structural families. A full method validation was performed for two lead compounds according to USFDA guidelines. The HILIC-MS/MS method was compatible with the physicochemical properties of gemini surfactants that bear a permanent positive charge with both hydrophilic and hydrophobic elements within their molecular structure. In addition, an effective liquid-liquid extraction method (98% recovery) was employed surpassing previously used extraction methods. The analysis of nanoparticle-treated cells showed an initial rise in the analyte intracellular concentration followed by a maximum and a somewhat more gradual decrease of the intracellular concentration. The observed intracellular depletion of the gemini surfactants may be attributable to their bio-transformation into metabolites and exocytosis from the host cells. Obtained cellular data showed a pattern that grants additional investigations, evaluating metabolite formation and assessing the subcellular distribution of tested compounds. Copyright © 2016 Elsevier B.V. All rights reserved.

Surfactant-thermal syntheses, structures, and magnetic properties of Mn-Ge-sulfides/selenides

KAUST Repository

Zhang, Guodong

2014-10-06

Although either surfactants or amines have been investigated to direct the crystal growth of metal chalcogenides, the synergic effect of organic amines and surfactants to control the crystal growth has not been explored. In this report, several organic bases (hydrazine monohydrate, ethylenediamine (en), 1,2-propanediamine (1,2-dap), and 1,3-propanediamine (1,3-dap)) have been employed as structure-directing agents (SDAs) to prepare four novel chalcogenides (Mn3Ge2S7(NH3)4 (1), [Mn(en)2(H2O)][Mn(en)2MnGe3Se9] (2), (1,2-dapH)2{[Mn(1,2-dap)2]Ge2Se7} (3), and (1,3-dapH)(puH)MnGeSe4(4) (pu = propyleneurea) under surfactant media (PEG-400). These as-prepared new crystalline materials provide diverse metal coordination geometries, including MnS3N tetrahedra, MnGe2Se7 trimer, and MnGe3Se10 T2 cluster. Compounds 1-3 have been fully characterized by single-crystal X-ray diffraction (XRD), powder XRD, UV-vis spectra, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Moreover, magnetic measurements for compound 1 showed an obvious antiferromagnetic transition at ∼9 K. Our research not only enriches the structural chemistry of the transitional-metal/14/16 chalcogenides but also allows us to better understand the synergic effect of organic amines and surfactants on the crystallization of metal chalcogenides.

ADSORPTION OF SURFACTANT ON CLAYS

Science.gov (United States)

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...

Electrostatic Screening and Charge Correlation Effects in Micellization of Ionic Surfactants

KAUST Repository

Jusufi, Arben

2009-05-07

We have used atomistic simulations to study the role of electrostatic screening and charge correlation effects in self-assembly processes of ionic surfactants into micelles. Specifically, we employed grand canonical Monte Carlo simulations to investigate the critical micelle concentration (cmc), aggregation number, and micellar shape in the presence of explicit sodium chloride (NaCl). The two systems investigated are cationic dodecyltrimethylammonium chloride (DTAC) and anionic sodium dodecyl sulfate (SDS) surfactants. Our explicit-salt results, obtained from a previously developed potential model with no further adjustment of its parameters, are in good agreement with experimental data for structural and thermodynamic micellar properties. We illustrate the importance of ion correlation effects by comparing these results with a Yukawa-type surfactant model that incorporates electrostatic screening implicitly. While the effect of salt on the cmc is well-reproduced even with the implicit Yukawa model, the aggregate size predictions deviate significantly from experimental observations at low salt concentrations. We attribute this discrepancy to the neglect of ion correlations in the implicit-salt model. At higher salt concentrations, we find reasonable agreement of the Yukawa model with experimental data. The crossover from low to high salt concentrations is reached when the electrostatic screening length becomes comparable to the headgroup size. © 2009 American Chemical Society.

Recovering hydrocarbons with surfactants from lignin

Energy Technology Data Exchange (ETDEWEB)

Naae, D.G.; Whittington, L.E.; Ledoux, W.A.; Debons, F.E.

1988-11-29

This patent describes a method of recovering hydrocarbons from an underground hydrocarbon formation penetrated by at least one injection well and at least one production well, which comprises: injecting into the formation through an injection well a surfactant slug comprising about 0.1% to about 10% by weight of surfactants produced from lignin, the surfactants produced by placing lignin in contact with water, converting the lignin into low molecular weight lignin phenols by reducing the lignin in the presence of a reducing agent of carbon monoxide or hydrogen creating a reduction reaction mixture comprising oil soluble lignin phenols, the reduction occurring at a temperature greater than about 200/sup 0/C and a pressure greater than about 100 psi, recovering the oil soluble lignin phenols from the reduction mixture, and converting the lignin phenols into lignin surfactants by a reaction selected from the group consisting of alkoxylation, sulfonation, sulfation, aklylation, sulfomethylation, and alkoxysulfation; injecting into the formation through the injection well a drive fluid to push the surfactant slug towards a production well; and recovering hydrocarbons at the production well.

Influence of metacide - surfactant complexes on agricultural crops

Directory of Open Access Journals (Sweden)

Orynkul Esimova

2014-12-01

Full Text Available The complexes based on surfactants and polyhexamethyleneguanidine hydrochloride (metacide are important for agriculture. This paper considers compositions of known bactericidal metacide with different surfactants: anionic surfactant sodium dodecylsulphate (DDSNa and nonionic surfactant Tween 80 (monooleate of oxyethylenated anhydrosorbitols. The effect of individual components and associates of metacide and surfactants on productivity and infection of cereals was studied. According to the study, the highest productivity and infection rate were shown by the associate of metacide and Tween-80. At concentration of Tween-80 in aqueous solution equal to 0.001% in combination with metacide, efficiency was 98% at 0% infection. The surface tension and the wetting of metacide, DDSNa, Tween-80, and associates of metacide with surfactants were studied. In comparison with individual components, metacide-DDSNa and metacide-Tween-80 associates have higher surface activity.

Physicochemical characteristics of PFC surfactants for dry decontamination

Energy Technology Data Exchange (ETDEWEB)

Oh, Won Jin; Lee, Chi Woo [Korea University, Seoul (Korea)

2001-04-01

Even the trace amount of the used nuclear fuels of high radioactivity are hazardous to the earth and humans. Perfluorocarbons and perfluorocarbon surfactants are emerging to be efficient chemicals in the dry decontamination process of the used fuels of high radioactivity. The theme was undertaken to increase the knowledge on perfluorocarbon surfactants to develop the perfluorocarbon system in the dry decontamination process in Korea. Several cationic and anionic pfc surfactants were synthesized. Effects of pfc surfactants on electrochemical etching of silicon were investigated to form porous silicons. Forces were measured between silicon surfaces and AFM tip in the absence and presence of pfc surfactants. 7 refs., 10 figs. (Author)

Tunable, antibacterial activity of silicone polyether surfactants.

Science.gov (United States)

Khan, Madiha F; Zepeda-Velazquez, Laura; Brook, Michael A

2015-08-01

Silicone surfactants are used in a variety of applications, however, limited data is available on the relationship between surfactant structure and biological activity. A series of seven nonionic, silicone polyether surfactants with known structures was tested for in vitro antibacterial activity against Escherichia coli BL21. The compounds varied in their hydrophobic head, comprised of branched silicone structures with 3-10 siloxane linkages and, in two cases, phenyl substitution, and hydrophilic tail of 8-44 poly(ethylene glycol) units. The surfactants were tested at three concentrations: below, at, and above their Critical Micelle Concentrations (CMC) against 5 concentrations of E. coli BL21 in a three-step assay comprised of a 14-24h turbidometric screen, a live-dead stain and viable colony counts. The bacterial concentration had little effect on antibacterial activity. For most of the surfactants, antibacterial activity was higher at concentrations above the CMC. Surfactants with smaller silicone head groups had as much as 4 times the bioactivity of surfactants with larger groups, with the smallest hydrophobe exhibiting potency equivalent to sodium dodecyl sulfate (SDS). Smaller PEG chains were similarly associated with higher potency. These data link lower micelle stability and enhanced permeability of smaller silicone head groups to antibacterial activity. The results demonstrate that simple manipulation of nonionic silicone polyether structure leads to significant changes in antibacterial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

Use of surfactants for the remediation of contaminated soils: A review

International Nuclear Information System (INIS)

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

2015-01-01

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

Use of surfactants for the remediation of contaminated soils: A review

Energy Technology Data Exchange (ETDEWEB)

Mao, Xuhui, E-mail: clab@whu.edu.cn [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Jiang, Rui; Xiao, Wei [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

2015-03-21

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

Understanding the Impact of Model Surfactants on Cloud Condensation Nuclei Activity of Sea Spray Aerosols

Science.gov (United States)

Forestieri, S.; Cappa, C. D.; Ruehl, C. R.; Bertram, T. H.; Staudt, S.; Kuborn, T.

2017-12-01

Aerosol impacts on cloud properties, also known as indirect effects, remain a major source of uncertainty in modeling global radiative forcing. Reducing this uncertainty necessitates better understanding of how aerosol chemical composition impacts the cloud-forming ability of aerosols. The presence of surfactants in aerosols can decrease the surface tension of activating droplets relative to water and lead to more efficient activation. The importance of this effect has been debated, but recent surface tension measurements of microscopic droplets indicate that surface tension is substantially depressed relative to water for lab-generated particles consisting of salt and a single organic species and for complex mixtures of organic matter. However, little work has been done on understanding how chemical complexity (i.e. interaction between different surfactant species) impacts surface tension for particles containing mixtures of surfactants. In this work, we quantified the surface tension of lab-generated aerosols containing surfactants that are commonly found in nascent sea spray aerosol (SSA) at humidities close to activation using a continuous flow stream-wise thermal gradient chamber (CFSTGC). Surface tension was quantified for particles containing single surfactant species and mixtures of these surfactants to investigate the role of chemical complexity on surface tension and molecular packing at the air-water interface. For all surfactants tested in this study, substantial surface tension depression (20-40 mN/m) relative to water was observed for particles containing large fractions of organic matter at humidities just below activation. However, the presence of these surfactants only weakly depressed surface tension at activation. Kinetic limitations were observed for particles coated with just palmitic acid, since palmitic acid molecules inhibit water uptake through their ability to pack tightly at the surface. However, these kinetic limitations disappeared when

Study of the effect of surfactants on extraction and determination of polyphenolic compounds and antioxidant capacity of fruits extracts.

Directory of Open Access Journals (Sweden)

Reza Hosseinzadeh

Full Text Available Micelle/water mixed solutions of different surface active agents were studied for their effectiveness in the extraction of polyphenolic compounds from various varieties of apples from west Azerbaijan province in Iran. The total content of polyphenolic compound in fruit extracts were determined using ferrous tartrate and Folin-Ciocalteu assays methods and chromatographic methods and compared with theme. High performance liquid chromatography is one of the most common and important methods in biochemical compound identification. The effect of pH, ionic strength, surfactant type, surfactant concentration, extraction time and common organic solvent in the apple polyphenolics extractions was studied using HPLC-DAD. Mixtures of surfactants, water and methanol at various ratios were examined and micellar-water solutions of Brij surfactant showed the highest polyphenol extraction efficiency. Optimum conditions for the extraction of polyphenolic compounds from apple occurred at 7 mM Brij35, pH 3. Effect of ionic strength on extraction was determined and 2% (W/V potassium Chloride was determined to be the optimum salt concentration. The procedure worked well with an ultrasound bath. Total antioxidant capacity also was determined in this study. The method can be safely scaled up for pharmaceutical applications.

Effect of a cationic surfactant on the volatilization of PAHs from soil.

Science.gov (United States)

Lu, Li; Zhu, Lizhong

2012-06-01

Cationic surfactants are common in soils because of their use in daily cosmetic and cleaning products, and their use as a soil amendment for the mitigation and remediation of organic contaminated soils has been proposed. Such surfactant may affect the transfer and fate of organic contaminants in the environment. This study investigated the effect of a cationic surfactant, dodecylpyridinium bromide (DDPB), on the volatilization of polycyclic aromatic hydrocarbons (PAHs) from a paddy soil. The volatilization of PAHs from moist soil amended with different concentrations of DDPB was tested in an open system. The specific effects of DDPB on the liquid-vapor and solid-vapor equilibriums of PAHs were separately investigated in closed systems by headspace analysis. DDPB affects both liquid-vapor and solid-vapor processes of PAHs in soil. At DDPB concentrations below the critical micelle concentration (CMC), movement of PAHs from the bulk solution to the gas-liquid interface appeared to be facilitated by interaction between PAHs and the surfactant monomers adsorbed at the gas-liquid interface, promoting the volatilization of PAHs from solution. However, when DDPB was greater than the CMC, volatilization was inhibited due to the solubilization of PAHs by micelles. On the other hand, the formation of sorbed surfactant significantly inhibited the solid-vapor volatilization of PAHs. The overall effect of the two simultaneous effects of DDPB on liquid-vapor and solid-vapor processes was a decreased volatilization loss of PAHs from soil. Inhibition of PAH volatilization was more significant for the soil with a lower moisture content.

Surfactant-Polymer Interaction for Improved Oil Recovery; FINAL

International Nuclear Information System (INIS)

Gabitto, Jorge; Mohanty, Kishore K.

2002-01-01

The goal of this research was to use the interaction between a surfactant and a polymer for efficient displacement of tertiary oil by improving slug integrity, oil solubility in the displacing fluid and mobility control. Surfactant-polymer flooding has been shown to be highly effective in laboratory-scale linear floods. The focus of this proposal is to design an inexpensive surfactant-polymer mixture that can efficiently recover tertiary oil by avoiding surfactant slug degradation and viscous/heterogeneity fingering

Surfactant properties of human meibomian lipids.

Science.gov (United States)

Mudgil, Poonam; Millar, Thomas J

2011-03-25

Human meibomian lipids are the major part of the lipid layer of the tear film. Their surfactant properties enable their spread across the aqueous layer and help maintain a stable tear film. The purpose of this study was to investigate surfactant properties of human meibomian lipids in vitro and to determine effects of different physical conditions such as temperature and increased osmolarity, such as occur in dry eye, on these properties. Human meibomian lipids were spread on an artificial tear solution in a Langmuir trough. The lipid films were compressed and expanded to record the surface pressure-area (Π-A) isocycles. The isocycles were recorded under different physical conditions such as high pressure, increasing concentration and size of divalent cations, increasing osmolarity, and varying temperature. Π-A isocycles of meibomian lipids showed that they form liquid films that are compressible and multilayered. The isocycles were unaffected by increasing concentration or size of divalent cations and increasing osmolarity in the subphase. Temperature had a marked effect on the lipids. Increase in temperature caused lipid films to become fluid, an expected feature, but decrease in temperature unexpectedly caused expansion of lipids and an increase in pressure suggesting enhanced surfactant properties. Human meibomian lipids form highly compressible, non-collapsible, multilayered liquid films. These lipids have surfactants that allow them to spread across an aqueous subphase. Their surfactant properties are unaffected by increasing divalent cations or hyperosmolarity but are sensitive to temperature. Cooling of meibomian lipids enhances their surfactant properties.

Cost Effective Surfactant Formulations for Improved Oil Recovery in Carbonate Reservoirs

Energy Technology Data Exchange (ETDEWEB)

William A. Goddard; Yongchun Tang; Patrick Shuler; Mario Blanco; Yongfu Wu

2007-09-30

power is pre-treated to make the surface oil-wet. The next step is to add the pre-treated powder to a test tube and add a candidate aqueous surfactant formulation; the greater the percentage of the calcite that now sinks to the bottom rather than floats, the more effective the surfactant is in changing the solids to become now preferentially water-wet. Results from the screening test generally are consistent with surfactant oil recovery performance reported in the literature. The second effort is a more fundamental study. It considers the effect of chemical structures of different naphthenic acids (NA) dissolved in decane as model oils that render calcite surfaces oil-wet to a different degree. NAs are common to crude oil and are at least partially responsible for the frequent observation that carbonate reservoirs are oil-wet. Because pure NA compounds are used, trends in wetting behavior can be related to NA molecular structure as measured by solid adsorption, contact angle and our novel, simple flotation test with calcite. Experiments with different surfactants and NA-treated calcite powder provide information about mechanisms responsible for sought after reversal to a water-wet state. Key findings include: (1) more hydrophobic NA's are more prone to induce oil-wetting, and (2) recovery of the model oil from limestone core was better with cationic surfactants, but one nonionic surfactant, Igepal CO-530, also had favorable results. This portion of the project included theoretical calculations to investigate key basic properties of several NAs such as their acidic strength and their relative water/oil solubility, and relate this to their chemical structure. The third category of this project focused on the recovery of a light crude oil from West Texas (McElroy Field) from a carbonate rock (limestone outcrop). For this effort, the first item was to establish a suite of surfactants that would be compatible with the McElroy Field brine. Those were examined further for

Surfactant selection for a liquid foam-bed photobioreactor.

Science.gov (United States)

Janoska, Agnes; Vázquez, María; Janssen, Marcel; Wijffels, René H; Cuaresma, María; Vílchez, Carlos

2018-02-01

A novel liquid foam-bed photobioreactor has been shown to hold potential as an innovative technology for microalgae production. In this study, a foam stabilizing agent has been selected which fits the requirements of use in a liquid foam-bed photobioreactor. Four criteria were used for an optimal surfactant: the surfactant should have good foaming properties, should not be rapidly biodegradable, should drag up microalgae in the foam formed, and it should not be toxic for microalgae. Ten different surfactants (nonionic, cationic, and anionic) and two microalgae genera (Chlorella and Scenedesmus) were compared on the above-mentioned criteria. The comparison showed the following facts. Firstly, poloxameric surfactants (Pluronic F68 and Pluronic P84) have acceptable foaming properties described by intermediate foam stability and liquid holdup and small bubble size. Secondly, the natural surfactants (BSA and Saponin) and Tween 20 were easily biodegraded by bacteria within 3 days. Thirdly, for all surfactants tested the microalgae concentration is reduced in the foam phase compared to the liquid phase with exception of the cationic surfactant CTAB. Lastly, only BSA, Saponin, Tween 20, and the two Pluronics were not toxic at concentrations of 10 CMC or higher. The findings of this study indicate that the Pluronics (F68 and P84) are the best surfactants regarding the above-mentioned criteria. Since Pluronic F68 performed slightly better, this surfactant is recommended for application in a liquid foam-bed photobioreactor. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018. © 2018 American Institute of Chemical Engineers.

History of surfactant up to 1980.

Science.gov (United States)

Obladen, Michael

2005-01-01

Remarkable insight into disturbed lung mechanics of preterm infants was gained in the 18th and 19th century by the founders of obstetrics and neonatology who not only observed respiratory failure but also designed devices to treat it. Surfactant research followed a splendid and largely logical growth curve. Pathological changes in the immature lung were characterized in Germany by Virchow in 1854 and by Hochheim in 1903. The Swiss physiologist von Neergard fully understood surfactant function in 1929, but his paper was ignored for 25 years. The physical properties of surfactant were recognized in the early 1950s from research on warfare chemicals by Pattle in Britain and by Radford and Clements in the United States. The causal relationship of respiratory distress syndrome (RDS) and surfactant deficiency was established in the USA by Avery and Mead in 1959. The Australian obstetrician Liggins induced lung maturity with glucocorticoids in 1972, but his discovery was not fully believed for another 20 years. A century of basic research was rewarded when Fujiwara introduced surfactant substitution in Japan in 1980 for treatment and prevention of RDS. Copyright 2005 S. Karger AG, Basel

Adsorption of anionic surfactants in limestone medium during oil recovery

Energy Technology Data Exchange (ETDEWEB)

Canbolat, Serhat; Bagci, Suat [Middle East Technical Univ., Dept. of Petroleum and Natural Gas Engineering, Ankara (Turkey)

2004-07-15

Foam-forming surfactant performance was evaluated by several experimental methods (interfacial tension, foam stability, corefloods) using commercial surfactants. There is considerable interest in the use of foam-forming surfactants for mobility control in water flood. To provide effective mobility control, the injected surfactant must propagate from the injection well toward the production well. One of the important parameters affecting propagation of foam-forming surfactant through the reservoir is the retention of surfactant due to its adsorption on reservoir rock. The determination of the adsorption of foam-forming surfactants in limestone reservoirs is important for the residual oil recovery efficiency. Adsorption measurements, recovery efficiencies, and surfactant and alkaline flooding experiments carried out with the representative of the selected surfactants alkaline solutions, linear alkyl benzene sulphonic acid (LABSA), sodium lauryl ether sulfate (SLES), and NaOH in a limestone medium. These surfactants were selected with respect to their foaming ability. Calibration curves formed by pH measurements were used to determine the correct adsorption amount of the used surfactants and recovery efficiency of these surfactants compared with base waterflooding. The results showed that LABSA adsorbed more than SLES in limestone reservoirs. The recovery efficiency of SLES was higher than the recovery efficiency of LABSA, and they decreased the recovery efficiency with respect to only the water injection case. (Author)

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

Science.gov (United States)

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

2015-03-21

Due to the great harm caused by soil contamination, there is an increasing interest to apply surfactants to the remediation of a variety of contaminated soils worldwide. This review article summarizes the findings of recent literatures regarding remediation of contaminated soils/sites using surfactants as an enhancing agent. For the surfactant-based remedial technologies, the adsorption behaviors of surfactants onto soil, the solubilizing capability of surfactants, and the toxicity and biocompatibility of surfactants are important considerations. Surfactants can enhance desorption of pollutants from soil, and promote bioremediation of organics by increasing bioavailability of pollutants. The removal of heavy metals and radionuclides from soils involves the mechanisms of dissolution, surfactant-associated complexation, and ionic exchange. In addition to the conventional ionic and nonionic surfactants, gemini surfactants and biosurfactants are also applied to soil remediation due to their benign features like lower critical micelle concentration (CMC) values and better biocompatibility. Mixed surfactant systems and combined use of surfactants with other additives are often adopted to improve the overall performance of soil washing solution for decontamination. Worldwide the field studies and full-scale remediation using surfactant-based technologies are yet limited, however, the already known cases reveal the good prospect of applying surfactant-based technologies to soil remediation. Copyright © 2014 Elsevier B.V. All rights reserved.

Silica micro- and nanoparticles reduce the toxicity of surfactant solutions.

Science.gov (United States)

Ríos, Francisco; Fernández-Arteaga, Alejandro; Fernández-Serrano, Mercedes; Jurado, Encarnación; Lechuga, Manuela

2018-04-20

In this work, the toxicity of hydrophilic fumed silica micro- and nanoparticles of various sizes (7 nm, 12 nm, and 50 μm) was evaluated using the luminescent bacteria Vibrio fischeri. In addition, the toxicity of an anionic surfactant solution (ether carboxylic acid), a nonionic surfactant solution (alkyl polyglucoside), and a binary (1:1) mixture of these solutions all containing these silica particles was evaluated. Furthermore, this work discusses the adsorption of surfactants onto particle surfaces and evaluates the effects of silica particles on the surface tension and critical micellar concentration (CMC) of these anionic and nonionic surfactants. It was determined that silica particles can be considered as non-toxic and that silica particles reduce the toxicity of surfactant solutions. Nevertheless, the toxicity reduction depends on the ionic character of the surfactants. Differences can be explained by the different adsorption behavior of surfactants onto the particle surface, which is weaker for nonionic surfactants than for anionic surfactants. Regarding the effects on surface tension, it was found that silica particles increased the surface activity of anionic surfactants and considerably reduced their CMC, whereas in the case of nonionic surfactants, the effects were reversed. Copyright © 2018 Elsevier B.V. All rights reserved.

Synergism and Physicochemical Properties of Anionic/Amphoteric Surfactant Mixtures with Nonionic Surfactant of Amine Oxide Type

Science.gov (United States)

Blagojević, S. M.; Pejić, N. D.; Blagojević, S. N.

2017-12-01

The physicochemical properties of initial formulation, that is anionic/amphoteric surfactants mixture SLES/AOS/CAB (sodium lauryl ether sulfate (SLES), α-olefin sulfonates (AOS) and cocamidopropyl betaine (CAB) at ratio 80 : 15 : 5) with nonionic surfactant of amine oxide type (lauramine oxide (AO)) in various concentration (1-5%) were studied. To characterize the surfactants mixture, the critical micelle concentration (CMC), surface tension (γ), foam volume, biodegradability and irritability were determined. This study showed that adding of AO in those mixtures lowered both γ and CMC as well as enhanced SLES/AOS/CAB foaming properties, but did not significantly affect biodegradability and irritability of initial formulation. Moreover, an increase in AO concentration has a meaningful synergistic effect on the initial formulation properties. All those results indicates that a nonionic surfactant of amine oxide type significantly improves the performance of anionic/amphoteric mixed micelle systems, and because of that anionic/amphoteric/nonionic mixture can be used in considerably lower concentrations as a cleaning formulation.

Evaluation of soy-based surface active copolymers as surfactant ingredients in model shampoo formulations.

Science.gov (United States)

Popadyuk, A; Kalita, H; Chisholm, B J; Voronov, A

2014-12-01

A new non-toxic soybean oil-based polymeric surfactant (SBPS) for personal-care products was developed and extensively characterized, including an evaluation of the polymeric surfactant performance in model shampoo formulations. To experimentally assure applicability of the soy-based macromolecules in shampoos, either in combination with common anionic surfactants (in this study, sodium lauryl sulfate, SLS) or as a single surface-active ingredient, the testing of SBPS physicochemical properties, performance and visual assessment of SBPS-based model shampoos was carried out. The results obtained, including foaming and cleaning ability of model formulations, were compared to those with only SLS as a surfactant as well as to SLS-free shampoos. Overall, the results show that the presence of SBPS improves cleaning, foaming, and conditioning of model formulations. SBPS-based formulations meet major requirements of multifunctional shampoos - mild detergency, foaming, good conditioning, and aesthetic appeal, which are comparable to commercially available shampoos. In addition, examination of SBPS/SLS mixtures in model shampoos showed that the presence of the SBPS enables the concentration of SLS to be significantly reduced without sacrificing shampoo performance. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Preparation of porous three-dimensional quaternary thioantimonates(III) ACuSb{sub 2}S{sub 4} (A=Rb, Cs) through a surfactant-thermal method

Energy Technology Data Exchange (ETDEWEB)

Shen, Yaying; Liu, Chang; Hou, Peipei; Zhi, Mingjia; Zhou, Chunmei; Liu, Yi [Zhejiang Univ., Hangzhou (China). State Key Lab. of Silicon Materials; Chai, Wenxiang [China Jiliang Univ., Hangzhou (China). College of Materials Science and Engineering; Cheng, Jian-Wen [Zhejiang Normal Univ., Jinhua (China). Inst. of Physical Chemistry; Zhang, Quichun [Nanyang Technological Univ., Singapore (Singapore). School of Materials Science and Engineering; Nanyang Technological Univ., Singapore (Singapore). Div. of Chemistry and Biological Chemistry

2015-12-15

Two novel porous three-dimensional quaternary thioantimonates(III) ACuSb{sub 2}S{sub 4} (A=Rb, Cs) were successfully synthesized by employing the neutral surfactant PEG-400 (PEG=polyethyleneglycol) as reaction media, these are significantly different from the known quaternary A-Cu-Sb-S thioantimonates(III) with two-dimensional (2D) crystal structures. This is the first time that crystalline quaternary chalcogenides have been prepared in surfactant media. Both experimental and theoretical studies confirm they are semiconductors with narrow band gaps. Our results demonstrated that the surfactant-thermal strategy could offer a new opportunity to explore novel chalcogenides with diverse crystal structures and interesting physicochemical properties.

Effects of an anionic surfactant (FFD-6) on the energy and information flow between a primary producer (Scenedesmus obliquus) and a consumer (Daphnia magna)

NARCIS (Netherlands)

Lürling, M.; de Lange, H.J.; Peeters, E.T.H.M.

2011-01-01

The effects of a commercially available anionic surfactant solution (FFD-6) on growth and morphology of a common green alga (Scenedesmus obliquus) and on survival and clearance rates of the water flea Daphnia magna were studied. The surfactant-solution elicited a morphological response (formation of

Surfactant therapy in late preterm infants

Directory of Open Access Journals (Sweden)

Murat Yurdakök

2013-06-01

Full Text Available Late preterm (LPT neonates are at a high risk for respiratory distress soon after birth due to respiratory distress syndrome (RDS, transient tachypnea of the newborn, persistent pulmonary hypertension, and pneumonia along with an increased need for surfactant replacement therapy, continuous positive airway pressure, and ventilator support when compared with the term neonates. In the past, studies on outcomes of infants with respiratory distress have primarily focused on extremely premature infants, leading to a gap in knowledge and understanding of the developmental biology and mechanism of pulmonary diseases in LPT neonates. Surfactant deficiency is the most frequent etiology of RDS in very preterm and moderately preterm infants, while cesarean section and lung infection play major roles in RDS development in LPT infants. The clinical presentation and the response to surfactant therapy in LPT infants may be different than that seen in very preterm infants. Incidence of pneumonia and occurrence of pneumothorax are significantly higher in LPT and term infants. High rates of pneumonia in these infants may result in direct injury to the type II alveolar cells of the lung with decreasing synthesis, release, and processing of surfactant. Increased permeability of the alveolar capillary membrane to both fluid and solutes is known to result in entry of plasma proteins into the alveolar hypophase, further inhibiting the surface properties of surfactant. However, the oxygenation index value do not change dramatically after ventilation or surfactant administration in LPT infants with RDS compared to very preterm infants. These finding may indicate a different pathogenesis of RDS in late preterm and term infants. In conclusion, surfactant therapy may be of significant benefit in LPT infants with serious respiratory failure secondary to a number of insults. However, optimal timing and dose of administration are not so clear in this group. Additional

Charging and Screening in Nonpolar Solutions of Nonionizable Surfactants

Science.gov (United States)

Behrens, Sven

2010-03-01

Nonpolar liquids do not easily accommodate electric charges, but surfactant additives are often found to dramatically increase the solution conductivity and promote surface charging of suspended colloid particles. Such surfactant-mediated electrostatic effects have been associated with equilibrium charge fluctuations among reverse surfactant micelles and in some cases with the statistically rare ionization of individual surfactant molecules. Here we present experimental evidence that even surfactants without any ionizable group can mediate charging and charge screening in nonpolar oils, and that they can do so at surfactant concentrations well below the critical micelle concentration (cmc). Precision conductometry, light scattering, and Karl-Fischer titration of sorbitan oleate solutions in hexane, paired with electrophoretic mobility measurements on suspended polymer particles, reveal a distinctly electrostatic action of the surfactant. We interpret our observations in terms of a charge fluctuation model and argue that the observed charging processes are likely facilitated, but not limited, by the presence of ionizable impurities.

Is surfactant a promising additive drug in ALI/ARDS-patients?

NARCIS (Netherlands)

Schultz, MJ; Kesecioglu, J

The rationale for surfactant replacement therapy in patients with acute respiratory distress syndrome (ARDS) is to restore the normal composition of the surfactant system, as well as to overcome ongoing inactivation of present surfactant. Indeed, surfactant replacement therapy call normalize the

Is surfactant a promising additive drug in ALI/ARDS-patients?

NARCIS (Netherlands)

Schultz, Marcus J.; Kesecioglu, Jozef

2004-01-01

The rationale for surfactant replacement therapy in patients with acute respiratory distress syndrome (ARDS) is to restore the normal composition of the surfactant system, as well as to overcome ongoing inactivation of present surfactant. Indeed, surfactant replacement therapy call normalize the

Maintained inspiratory activity during proportional assist ventilation in surfactant-depleted cats early after surfactant instillation: phrenic nerve and pulmonary stretch receptor activity

Directory of Open Access Journals (Sweden)

Schaller Peter

2006-03-01

Full Text Available Abstract Background Inspiratory activity is a prerequisite for successful application of patient triggered ventilation such as proportional assist ventilation (PAV. It has recently been reported that surfactant instillation increases the activity of slowly adapting pulmonary stretch receptors (PSRs followed by a shorter inspiratory time (Sindelar et al, J Appl Physiol, 2005 [Epub ahead of print]. Changes in lung mechanics, as observed in preterm infants with respiratory distress syndrome and after surfactant treatment, might therefore influence the inspiratory activity when applying PAV early after surfactant treatment. Objective To investigate the regulation of breathing and ventilatory response in surfactant-depleted young cats during PAV and during continuous positive airway pressure (CPAP early after surfactant instillation in relation to phrenic nerve activity (PNA and the activity of PSRs. Methods Seven anesthetized, endotracheally intubated young cats were exposed to periods of CPAP and PAV with the same end-expiratory pressure (0.2–0.5 kPa before and after lung lavage and after surfactant instillation. PAV was set to compensate for 75% of the lung elastic recoil. Results Tidal volume and respiratory rate were higher with lower PaCO2 and higher PaO2 during PAV than during CPAP both before and after surfactant instillation (p Conclusion PSR activity and the control of breathing are maintained during PAV in surfactant-depleted cats early after surfactant instillation, with a higher ventilatory response and a lower breathing effort than during CPAP.

Synthesis and properties evaluation of sulfobetaine surfactant with double hydroxyl

Science.gov (United States)

Zhou, Ming; Luo, Gang; Zhang, Ze; Li, Sisi; Wang, Chengwen

2017-09-01

A series of sulfobetaine surfactants {N-[(3-alkoxy-2-hydroxyl)propoxy] ethyl-N,N-dimethyl-N-(2-hydroxyl)propyl sulfonate} ammonium chloride were synthesized with raw materials containing linear saturated alcohol, N,N-dimethylethanolamine, sodium 3-chloro-2-hydroxyl propane sulfonic acid and epichlorohydrin. The molecule structures of sulfobetaine surfactants were characterized by FTIR, 1HNMR and elemental analysis. Surface tension measurements can provide us information about the surface tension at the CMC (γCMC), pC20, Γmax and Amin. The pC20 values of sulfobetaine surfactants increase with the hydrophobic chain length increasing. Amin values of the surfactants decrease with increasing hydrophobic chain length from 10 to 14. The critical micelle concentration (CMC) and surface tension (γCMC) values of the sulfobetaine surfactants decrease with increasing hydrophobic chain length from 10 to 16. The lipophilicity of surfactant was enhanced with the increase of the carbon chain, however, the ability of anti-hard water was weakened. The minimum oil/water interfacial tension of four kinds of sulfobetaine surfactants is 10-2-10-3 mN/m magnitude, which indicates that the synthesized bis-hydroxy sulfobetaine surfactants have a great ability to reduce interfacial tension in the surfactant flooding system. The surface tension (γCMC) values of synthesized surfactants were lower compared with conventional anionic surfactant sodium dodecyl sulfonate.

Surfactant treatment before first breath for respiratory distress syndrome in preterm lambs: comparison of a peptide-containing synthetic lung surfactant with porcine-derived surfactant

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van Zyl JM

2013-08-01

Full Text Available Johann M van Zyl,1 Johan Smith2 1Division of Pharmacology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa; 2Department of Paediatrics and Child Health, Tygerberg Children's Hospital, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa Background: In a recent study utilizing a saline-lavaged adult rabbit model, we described a significant improvement in systemic oxygenation and pulmonary shunt after the instillation of a novel synthetic peptide-containing surfactant, Synsurf. Respiratory distress syndrome in the preterm lamb more closely resembles that of the human infant, as their blood gas, pH values, and lung mechanics deteriorate dramatically from birth despite ventilator support. Moreover, premature lambs have lungs which are mechanically unstable, with the advantage of being able to measure multiple variables over extended periods. Our objective in this study was to investigate if Synsurf leads to improved systemic oxygenation, lung mechanics, and histology in comparison to the commercially available porcine-derived lung surfactant Curosurf® when administered before first breath in a preterm lamb model. Materials and methods: A Cesarean section was performed under general anesthesia on 18 time-dated pregnant Dohne Merino ewes at 129–130 days gestation. The premature lambs were delivered and ventilated with an expiratory tidal volume of 6–8 mL/kg for the first 30 minutes and thereafter at 8–10 mL/kg. In a randomized controlled trial, the two surfactants tested were Synsurf and Curosurf®, both at a dose of 100 mg/kg phospholipids (1,2-dipalmitoyl-L-α-phosphatidylcholine; 90% in Synsurf, 40% in Curosurf®. A control group of animals was treated with normal saline. Measurements of physiological variables, blood gases, and lung mechanics were made before and after surfactant and saline replacement and at 15, 30, 45, 60, 90, 120, 180

Surfactant use with nitrate-based bioremediation

International Nuclear Information System (INIS)

Wilson, B.H.; Hutchins, S.R.; West, C.C.

1995-01-01

This study presents results of an initial survey on the effect of six surfactants on the biodegradation of petroleum hydrocarbons in bioremediation applications using nitrate as the electron acceptor. Aquifer material from Park City, Kansas, was used for the study. The three atomic surfactants chosen were Steol CS-330, Dowfax 8390 and sodium dodecylbenzene sulfonate (SDBS); the three nonionic surfactants were T-MAZ-60, Triton X-100, and Igepal CO-660. Both Steol CS-330 and T-MAZ-60 biodegraded under denitrifying conditions. The Steol inhibited biodegradation of benzene, toluene, ethylbenzene, xylenes, and trimethylbenzenes (BTEXTMB). Only toluene was rapidly degraded in the presence of T-MAZ-60. Biodegradation of all compounds, including toluene, appears to be inhibited by Dowfax 8390 and SDBS. No biodegradation of Dowfax 8390 or SDBS was observed. SDBS inhibited denitrification, but Dowfax 8390 did not. For the microcosms containing Triton X-100 or Igepal CO-660, removal of toluene, ethylbenzene, m-xylene, 1,3,5-TMB, and 1,2,4-TMB were similar to their removals in the no-surfactant treatment. These two surfactants did not biodegrade, did not inhibit biodegradation of the alkylbenzenes, and did not inhibit denitrification. Further studies are continuing with aquifer material from Eglin Air Force Base

Foaming behaviour of polymer-surfactant solutions

International Nuclear Information System (INIS)

Cervantes-MartInez, Alfredo; Maldonado, Amir

2007-01-01

We study the effect of a non-ionic amphiphilic polymer (PEG-100 stearate also called Myrj 59) on the foaming behaviour of aqueous solutions of an anionic surfactant (sodium dodecyl sulfate or SDS). The SDS concentration was kept fixed while the Myrj 59 concentration was varied. Measurements of foamability, surface tension and electrical conductivity were carried out. The results show two opposite effects depending on the polymer concentration: foamability is higher when the Myrj 59 concentration is low; however, it decreases considerably when the polymer concentration is increased. This behaviour is due to the polymer adsorption at the air/liquid interface at lower polymer concentrations, and to the formation of a polymer-surfactant complex in the bulk at higher concentrations. The results are confirmed by surface tension and electrical conductivity measurements, which are interpreted in terms of the microstructure of the polymer-surfactant solutions. The observed behaviour is due to the amphiphilic nature of the studied polymer. The increased hydrophobicity of Myrj 59, compared to that of water-soluble polymers like PEG or PEO, increases its 'reactivity' towards SDS, i.e. the strength of its interaction with this anionic surfactant. Our results show that hydrophobically modified polymers have potential applications as additives in order to control the foaming properties of surfactant solutions

Surfactant Sensors in Biotechnology; Part 1 – Electrochemical Sensors

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Milan Sak-Bosnar

2004-01-01

Full Text Available An overview on electrochemical surfactant sensors is given with special attention to papers published since 1993. The importance of surfactants in modern biotechnology is stressed out. Electrochemical sensors are usually divided according to the measured physical quantity to potentiometric, amperometric, conductometric and impedimetric surfactant sensors. The last ones are very few. Potentiometric surfactant sensors are the most numerous due to their simplicity and versatility. They can be used either as end-point titration sensors or as direct EMF measurement sensors, in batch or flow-through mode. Some amperometric surfactant sensors are true biosensors that use microorganisms or living cells.

A level-set method for two-phase flows with soluble surfactant

Science.gov (United States)

Xu, Jian-Jun; Shi, Weidong; Lai, Ming-Chih

2018-01-01

A level-set method is presented for solving two-phase flows with soluble surfactant. The Navier-Stokes equations are solved along with the bulk surfactant and the interfacial surfactant equations. In particular, the convection-diffusion equation for the bulk surfactant on the irregular moving domain is solved by using a level-set based diffusive-domain method. A conservation law for the total surfactant mass is derived, and a re-scaling procedure for the surfactant concentrations is proposed to compensate for the surfactant mass loss due to numerical diffusion. The whole numerical algorithm is easy for implementation. Several numerical simulations in 2D and 3D show the effects of surfactant solubility on drop dynamics under shear flow.

Performance enhancement of NdFeB nanoflakes prepared by surfactant-assisted ball milling at low temperature by using different surfactants

Science.gov (United States)

An, Xiaoxin; Jin, Kunpeng; Wang, Fang; Fang, Qiuli; Du, Juan; Xia, Weixing; Yan, Aru; Liu, J. Ping; Zhang, Jian

2017-02-01

Hard magnetic NdFeB submicron and nanoflakes were successfully prepared by surfactant-assisted ball milling at room temperature (SABMRT) and low temperature (SABMLT) by using oleic acid (OA), oleylamine (OLA) and trioctylamine (TOA) as surfactant, respectively. Among the surfactants used, OA and OLA have similar effects on the morphology of the NdFeB nanoflakes milled at both room and low temperature. In the case of TOA, irregular micron-sized particles and submirco/nanoflakes were obtained for the NdFeB powders prepared by SABMRT and SABMLT, respectively. Samples prepared by SABMLT show better crystallinity and better degree of grain alignment than that prepared by SABMRT with the same surfactant. Comparing with the samples milled at RT, higher coercivity and larger remanence ratio were achieved in the NdFeB samples prepared at LT. The amounts of residual surfactants in final NdFeB powders were also calculated, which reveals that the final NdFeB powders milled at LT possess lower amount of residual surfactants than those milled at RT. It was found that lowering milling temperature of SABM would be a promising way for fabricating permanent magnetic materials with better hard magnetic properties.

Common genetic variants of surfactant protein-D (SP-D are associated with type 2 diabetes.

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Neus Pueyo

Full Text Available CONTEXT: Surfactant protein-D (SP-D is a primordial component of the innate immune system intrinsically linked to metabolic pathways. We aimed to study the association of single nucleotide polymorphisms (SNPs affecting SP-D with insulin resistance and type 2 diabetes (T2D. RESEARCH DESIGN AND METHODS: We evaluated a common genetic variant located in the SP-D coding region (rs721917, Met(31Thr in a sample of T2D patients and non-diabetic controls (n = 2,711. In a subset of subjects (n = 1,062, this SNP was analyzed in association with circulating SP-D concentrations, insulin resistance, and T2D. This SNP and others were also screened in the publicly available Genome Wide Association (GWA database of the Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC. RESULTS: We found the significant association of rs721917 with circulating SP-D, parameters of insulin resistance and T2D. Indeed, G carriers showed decreased circulating SP-D (p = 0.004, decreased fasting glucose (p = 0.0002, glycated hemoglobin (p = 0.0005, and 33% (p = 0.002 lower prevalence of T2D, estimated under a dominant model, especially among women. Interestingly, these differences remained significant after controlling for origin, age, gender, and circulating SP-D. Moreover, this SNP and others within the SP-D genomic region (i.e. rs10887344 were significantly associated with quantitative measures of glucose homeostasis, insulin sensitivity, and T2D, according to GWAS datasets from MAGIC. CONCLUSIONS: SP-D gene polymorphisms are associated with insulin resistance and T2D. These associations are independent of circulating SP-D concentrations.

Electrodialytic remediation of polychlorinated biphenyls contaminated soil with iron nanoparticles and two different surfactants

DEFF Research Database (Denmark)

Gomes, Helena I.; Dias-Ferreira, Celia; Ottosen, Lisbeth M.

2014-01-01

Polychlorinated biphenyls (PCB) are persistent organic pollutants (POP) that strongly adsorb in soils and sediments. There is a need to develop new and cost-effective solutions for the remediation of PCB contaminated soils. The suspended electrodialytic remediation combined with zero valent iron......ZVI showed encouraging tendencies and a base is thus formed for further optimization towards a new method for remediation of PCB polluted soils....... nanoparticles (nZVI) could be a competitive alternative to the commonly adapted solutions of incineration or landfilling. Surfactants can enhance the PCB desorption, dechlorination, and the contaminated soil cleanup. In this work, two different surfactants (saponin and Tween 80) were tested to enhance PCB...

Poly(ethylene oxide) surfactant polymers

OpenAIRE

VACHEETHASANEE, KATANCHALEE; WANG, SHUWU; QIU, YONGXING; MARCHANT, ROGER E.

2004-01-01

We report on a series of structurally well-defined surfactant polymers that undergo surface-induced self-assembly on hydrophobic biomaterial surfaces. The surfactant polymers consist of a poly(vinyl amine) backbone with poly(ethylene oxide) and hexanal pendant groups. The poly(vinyl amine) (PVAm) was synthesized by hydrolysis of poly(N-vinyl formamide) following free radical polymerization of N-vinyl formamide. Hexanal and aldehyde-terminated poly (ethyleneoxide) (PEO) were simultaneously att...

ASSOCIATION OF BRANCHED POLYETHYLENE IMINE WITH SURFACTANTS IN AQUEOUS SOLUTION

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Ismael C. Bellettini

2015-07-01

Full Text Available Three polymer-surfactant systems comprised of branched polyethylene imine (PEI with an anionic surfactant (sodium dodecylsulfate; SDS, a cationic surfactant (tetradecyltrimethylammonium bromide; TTAB, and a zwitterionic surfactant (N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate; SB3-14 were studied based on the properties of surface tension, pyrene fluorescence emission, dynamic light scattering, pH, and zeta potential measurements. The critical aggregation concentration (cac and polymer saturation point (psp were determined for all three systems. The effect of these surfactants on the physico-chemical characteristics (diameter and surface charge of the complexes formed was determined. Polymer-surfactant interactions occurred in all of the systems studied, with the strongest interactions, electrostatic in nature, occurring in the SDS-PEI system. After the neutralization of the polymer charges with the addition of the surfactant, the hydrophobic effect started to control the interlacing of the polymer chains. For the PEI-TTAB system, a very dense film was formed at surfactant concentrations above 2.0 mmol L-1. In this case, the bromide counter-ion interacted with both the positively-charged PEI and the head of the surfactant, which is responsible for the formation of double layer coordination complexes. For the system composed of PEI and the zwitterionic surfactant, less cooperative associations occurred in comparison with the other systems.

Effect of non-homogeneous spatial distributions of surfactants on the stability of high-content bitumen-in-water emulsions

International Nuclear Information System (INIS)

Urbina-Villalba, German; Garcia-Sucre, Maximo

2000-01-01

In order to study the effects of non-homogeneous spatial distributions of surfactants on the drop size of high-content bitumen-in-water emulsions, a modification of a standard Brownian Dynamics algorithm was employed. The new algorithm is able to simulate the evolution of oil/water emulsions towards flocculation and coalescence. The simulation boxes contain 216 and 125 particles initially distributed in a homogeneous simple cubic arrangement, corresponding to bitumen/water volume fractions of 0.30 and 0.51, respectively. The particles interact through a DLVO potential dependent on the total surfactant concentration, spatial surfactant distribution, and the amount of surfactant adsorbed to the bitumen/water interface. As will be shown in this article, certain combinations of the referred variables can produce a wide variety of repulsive potentials between similar drops. The variation of the total number of drops with time does not obey the usual analytical formalisms developed for more diluted cases, and instead, a simple exponential decrease of the number of drops with time is found. Such behavior has already been confirmed by experiment. Some similarities between the present results and those previously published for more diluted systems are discussed [es

The effect of nanoparticle aggregation on surfactant foam stability.

Science.gov (United States)

AlYousef, Zuhair A; Almobarky, Mohammed A; Schechter, David S

2018-02-01

The combination of nanoparticles (NPs) and surfactant may offer a novel technique of generating stronger foams for gas mobility control. This study evaluates the potential of silica NPs to enhance the foam stability of three nonionic surfactants. Results showed that the concentration of surfactant and NPs is a crucial parameter for foam stability and that there is certain concentrations for strong foam generation. A balance in concentration between the nonionic surfactants and the NPs can enhance the foam stability as a result of forming flocs in solutions. At fixed surfactant concentration, the addition of NPs at low to intermediate concentrations can produce a more stable foam compared to the surfactant. The production of small population of flocs as a result of mixing the surfactant and NPs can enhance the foam stability by providing a barrier between the gas bubbles and delaying the coalescence of bubbles. Moreover, these flocs can increase the solution viscosity and, therefore, slow the drainage rate of thin aqueous film (lamellae). The measurements of foam half-life, bubble size, and mobility tests confirmed this conclusion. However, the addition of more solid particles or surfactant might have a negative impact on foam stability and reduce the maximum capillary pressure of coalescence as a result of forming extensive aggregates. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of Surfactants on the Deformation and Detachment of Oil Droplets in a Model Laminar Flow Cell

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Fréville V.

2013-10-01

Full Text Available Sugar-based surfactants are increasingly present in the development of eco-friendly detergents due to current regulations and consumer demand. In order to assess the degreasing performance of these new surfactants, the behavior of model oil droplets subjected to the action of a flow of surfactant solutions of different concentrations was studied in a laminar flow cell and related to the physico-chemical properties measured at the liquid/liquid (interfacial tension and solid/liquid/liquid interfaces (contact angle. With the surfactant solutions and the model oils employed in this study, three main behaviors were observed when a critical flow rate was reached: elongation, fragmentation or spontaneous detachment of the droplet. The analysis of the results leads to a correlation between the droplet behavior and the balance of the forces applied on the droplet in its initial position, in particular the gravity force Fg, which tends to move the oil droplet upwards (given the density difference, and the capillary force Fc, which tends to keep the droplet spherical. A state diagram could be established, based on the dimensionless Bond number (Fg/Fc and cosθ, θ being the initial contact angle of the drop on the surface before the establishment of the flow. One can thus predict the droplet behavior as a function of the system initial characteristics. The results allowed the comparison of degreasing performance of the different surfactants used and illustrated the potential of AlkylPolyPentosides (APP for detergent formulations.

Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

Science.gov (United States)

Smith, Douglas D.; Hiller, John M.

1998-01-01

The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration.

Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

Science.gov (United States)

Smith, D.D.; Hiller, J.M.

1998-02-24

The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration. 1 fig.

HPLC/ESI-quadrupole ion trap mass spectrometry for characterization and direct quantification of amphoteric and nonionic surfactants in aqueous samples

Science.gov (United States)

Levine, Lanfang H.; Garland, Jay L.; Johnson, Jodie V.

2002-01-01

An amphoteric (cocamidopropylbetaine, CAPB) and a nonionic (alcohol polyethoxylate, AE) surfactant were characterized by electrospray ionization quadrupole ion trap mass spectrometry (ESI-MS) as to their homologue distribution and ionization/fragmentation chemistry. Quantitative methods involving reversed-phase gradient HPLC and (+)ESI-MSn were developed to directly determine these surfactants in hydroponic plant growth medium that received simulated graywater. The predominant homologues, 12 C alkyl CAPB and 9 EO AE, were monitored to represent the total amount of the respective surfactants. The methods demonstrated dynamic linear ranges of 0.5-250 ng (r2 > 0.996) for CAPB and 8-560 ng (r2 > 0.998) for AE homologue mixture, corresponding to minimum quantification limits of 25 ppb CAPB and 0.4 ppm AE with 20-microL injections. This translated into an even lower limit for individual components due to the polydispersive nature of the surfactants. The procedure was successfully employed for the assessment of CAPB and AE biodegradation in a hydroponic plant growth system used as a graywater bioreactor.

Biomarker analysis of liver cells exposed to surfactant-wrapped and oxidized multi-walled carbon nanotubes (MWCNTs)

Science.gov (United States)

Carbon nanotubes (CNTs) have great potential in industrial, consumer, and mechanical applications, based partly on their unique structural, optical and electronic properties. CNTs are commonly oxidized or treated with surfactants to facilitate aqueous solution processing, and the...

Acute toxicity of anionic and non-ionic surfactants to aquatic organisms.

Science.gov (United States)

Lechuga, M; Fernández-Serrano, M; Jurado, E; Núñez-Olea, J; Ríos, F

2016-03-01

The environmental risk of surfactants requires toxicity measurements. As different test organisms have different sensitivity to the toxics, it is necessary to establish the most appropriate organism to classify the surfactant as very toxic, toxic, harmful or safe, in order to establish the maximum permissible concentrations in aquatic ecosystems. We have determined the toxicity values of various anionic surfactants ether carboxylic derivatives using four test organisms: the freshwater crustacean Daphnia magna, the luminescent bacterium Vibrio fischeri, the microalgae Selenastrum capricornutum (freshwater algae) and Phaeodactylum tricornutum (seawater algae). In addition, in order to compare and classify the different families of surfactants, we have included a compilation of toxicity data of surfactants collected from literature. The results indicated that V. fischeri was more sensitive to the toxic effects of the surfactants than was D. magna or the microalgae, which was the least sensitive. This result shows that the most suitable toxicity assay for surfactants may be the one using V. fischeri. The toxicity data revealed considerable variation in toxicity responses with the structure of the surfactants regardless of the species tested. The toxicity data have been related to the structure of the surfactants, giving a mathematical relationship that helps to predict the toxic potential of a surfactant from its structure. Model-predicted toxicity agreed well with toxicity values reported in the literature for several surfactants previously studied. Predictive models of toxicity is a handy tool for providing a risk assessment that can be useful to establish the toxicity range for each surfactant and the different test organisms in order to select efficient surfactants with a lower impact on the aquatic environment. Copyright © 2015 Elsevier Inc. All rights reserved.

Surfactant protein D in newborn infants

DEFF Research Database (Denmark)

Dahl, Marianne; Juvonen, Pekka Olavi; Holmskov, Uffe

2005-01-01

Surfactant protein D (SP-D) is a collectin that plays an important role in the innate immune system. The role of SP-D in the metabolism of surfactant is as yet quite unclear. The aims of this study were to establish normal values of SP-D in the umbilical cord blood and capillary blood of mature...

Influence of stability of polymer surfactant on oil displacement mechanism

Science.gov (United States)

Liu, Li; Li, Chengliang; Pi, Yanming; Wu, Di; He, Ying; Geng, Liang

2018-02-01

At present, most of the oilfields of China have entered the late stage of high water-cut development, and three oil recovery technique has become the leading technology for improving oil recovery. With the improvement of three oil recovery techniques, the polymer surfactant flooding technology has been widely promoted in oil fields in recent years. But in the actual field experiment, it has been found that the polymer surfactant has chromatographic separation at the extraction end, which indicates that the property of the polymer surfactant has changed during the displacement process. At present, there was few literature about how the stability of polymer surfactant affects the oil displacement mechanism. This paper used HuaDing-I polymer surfactant to conduct a micro photolithography glass flooding experiment, and then compared the oil displacement law of polymer surfactant before and after static setting. Finally, the influence law of stability of polymer surfactant on the oil displacement mechanism is obtained by comprehensive analysis.

Assessment of the potential skin irritation of lysine-derivative anionic surfactants using mouse fibroblast and human keratinocytes as an alternative to animal testing

OpenAIRE

Sánchez Molina, Lourdes; Mitjans Arnal, Montserrat; Infante Martínez-Pardo, Ma. Rosa; Vinardell Martínez-Hidalgo, Ma. Pilar

2004-01-01

Purpose. The aim of this study was to identify new surfactants with low skin irritant properties for use in pharmaceutical and cosmetic formulations, employing cell culture as an alternative method to in vivo testing. In addition, we sought to establish whether potential cytotoxic properties were related to the size of the counterions bound to the surfactants. Methods. Cytotoxicity was assessed in the mouse fibroblast cell line 3T6, and the human keratinocyte cell line NCTC 2544, using the MT...

FLOTATION DE-INKING OF 50% ONP/ 50% OMG RECOVERED PAPERS MIXTURES USING NONIONIC SURFACTANT, SOAP, AND SURFACTANT/SOAP BLENDS

Directory of Open Access Journals (Sweden)

Jeremy Allix

2010-11-01

Full Text Available A laboratory flotation column equipped with Venturi aerators and an adjustable froth removal system was used to study the effect of calcium soap and a mixture of calcium soap/alkyl phenol ethoxylate surfactant on ink and fibres transfer during flotation de-inking of a 50% old newprint (ONP / 50% old magazines (OMG recovered papers mixture. Mass transport phenomena determining the yield of the flotation process were interpreted using model equations describing particle removal in terms of flotation, entrainment, and drainage in the froth. A decrease in the ink and mineral fillers flotation rate constant, drainage through the froth, and in fibre entrainment was observed when increasing the surfactant concentration. These trends were consistent with the typical dispersing action of the studied nonionic surfactant. An opposite effect on ink and fillers was observed when using calcium soap alone, and the increase in the flotation rate constant and drainage through the froth were consistent with the collecting and defoaming action of the calcium soap. Moreover, fibre entrainment decreased when increasing the soap concentration. The study of the surfactant/soap mixture highlighted the absence of synergy between the calcium soap and the surfactant.

A novel lignin-based surfactant system for the Salem Unit

International Nuclear Information System (INIS)

DeBons, F.E.; Whittington, L.E.

1991-01-01

Texaco conducted a successful surfactant/polymer flood in a 60-acre [24 ha] portion of the Salem Benoist reservoir in Salem, Illinois, in 1981. This pilot used a brine-tolerant petroleum sulfonate surfactant system blended in injection brine followed by a xanthan mobility control polymer in fresher water. The oil recovery over the seven year life of the flood was 487,050 bbl [77 435 m 3 ]. This represents 45% of the oil remaining in the total thickness of 73% of that from the more permeable lower interval where most of the surfactant flowed. Since this successful project, Texaco has continued to improve enhanced oil recovery surfactant systems. We have developed novel, brine tolerant surfactants based on the renewable resources lignin and tallow amine. This paper describes the laboratory work leading to a surfactant system which has been recommended for field testing. The laboratory work includes blending, interfacial tension measurements, and core floods in Berea and reservoir cores. The type of lignin based surfactant system described in this report has applicability in all fields where conventional petroleum-based surfactants have been used. Their much lower cost means that they can be used economically at lower crude oil prices

Nonlinear vibrational spectroscopy of surfactants at liquid interfaces

Energy Technology Data Exchange (ETDEWEB)

Miranda, Paulo B. [Univ. of California, Berkeley, CA (United States)

1998-12-14

Surfactants are widely used to modify physical and chemical properties of interfaces. They play an important role in many technological problems. Surfactant monolayer are also of great scientific interest because they are two-dimensional systems that may exhibit a very rich phase transition behavior and can also be considered as a model system for biological interfaces. In this Thesis, we use a second-order nonlinear optical technique (Sum-Frequency Generation - SFG) to obtain vibrational spectra of surfactant monolayer at Iiquidhapor and solid/liquid interfaces. The technique has several advantages: it is intrinsically surface-specific, can be applied to buried interfaces, has submonolayer sensitivity and is remarkably sensitive to the confirmational order of surfactant monolayers.

The Inhibiting or Accelerating Effect of Different Surfactants on ...

African Journals Online (AJOL)

The course of differential capacity curves of the electric double layer at the mercury electrode/surfactant solution interface was described for three different surfactants from different groups. Using square-wave voltammetry (SWV) it was found that the surfactants had a varying effect on the kinetics of electroreduction of Zn2+ ...

Effect of Gemini-type surfactant on methane hydrate formation

Energy Technology Data Exchange (ETDEWEB)

Jeong, K.E.; Park, J.M.; Kim, C.U.; Chae, H.J.; Jeong, S.Y. [Korea Research Inst. of Chemical Technology, Jang-Dong, Yuseong-Gu, Daejeon (Korea, Republic of)

2008-07-01

Natural gas hydrates are formed from water and natural gas molecules at particular temperatures and pressures that become ice-like inclusion compounds. Gas hydrates offer several benefits such as energy resource potential and high storage capacity of natural gas in the form of hydrates. However, the application of natural gas hydrates has been deterred by its low formation rate and low conversion ratio of water into hydrate resulting in low actual storage capacity. This paper presented an experimental study to determine the effect of adding a novel Gemini-type surfactant on methane hydrate formation. The experimental study was described with reference to the properties of prepared diols and properties of prepared disulfonates. Gemini surfactant is the family of surfactant molecules possessing more than one hydrophobic tail and hydrophilic head group. They generally have better surface-active properties than conventional surfactants of equal chain length. The paper presented the results of the study in terms of the reactions of diols with propane sultone; storage capacity of hydrate formed with and without surfactant; and methane hydrate formation with and without disulfonate. It was concluded that the methane hydrate formation was accelerated by the addition of novel anionic Gemini-type surfactants and that hydrate formation was influenced by the surfactant concentration and alkyl chain length. For a given concentration, the surfactant with the highest chain length demonstrated the highest formation rate and storage capacity. 5 refs., 3 tabs., 4 figs.

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

Science.gov (United States)

Hassan, A K

2015-01-01

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

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

Directory of Open Access Journals (Sweden)

Mahdi ES

2011-06-01

Full Text Available Elrashid Saleh Mahdi1, Mohamed HF Sakeena1, Muthanna F Abdulkarim1, Ghassan Z Abdullah1,3, Munavvar Abdul Sattar2, Azmin Mohd Noor11Department of Pharmaceutical Technology, 2Department of Physiology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia; 3Department of Pharmaceutical Technology, International Medical University, Bukit Jalil, Kuala Lumpur, MalaysiaBackground: 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

Tailor-made surfactants for optimized chemical EOR. Meeting oil reservoir conditions by applied knowledge of structure-performance relationship in extended surfactants

Energy Technology Data Exchange (ETDEWEB)

Trahan, G.; Sorensen, W. [Sasol North America Inc., Westlake, LA (United States); Jakobs-Sauter, B. [Sasol Germany GmbH (Germany)

2013-08-01

Formulating the surfactant package for chemical EOR is a time consuming and expensive process - the formulation needs to fit the specific reservoir conditions (like oil type, temperature, salinity, etc.) to give optimum performance and the number of formulation variables is virtually endless. This paper studies the impact of surfactant structure on EOR formulation ability and performance and how to adjust the structure of the surfactant molecule to meet a specific reservoir's needs. Data from salinity phase boundary studies of alcohol propoxy sulfates illustrate how changes in alcohol structure as well as in propylene oxide level can shift optimum salinity and temperature to the desired range in a given model oil. From these data the impact of individual structural units was evaluated. Application of the HLD model (Hydrophilic-Lipophilic Deviation) shows how to extrapolate from the known data set to actual reservoir conditions. This is illustrated by studies on crude oil samples. Additional tests study how effective the selected surfactants perform. The HLD concept proves to be a valuable tool to select and tailor surfactants to individual reservoir needs, thus simplifying the surfactant screening process for EOR formulations by pre-selection of suitable structures and ultimately reducing cost and effort on the way to the most effective chemical EOR package. (orig.)

MICROBIAL SURFACTANTS. I. GLYCOLIPIDS

Directory of Open Access Journals (Sweden)

Pirog T. Р.

2014-02-01

Full Text Available The review is devoted to surface-active glycolipids. The general characteristics, the physiological role of the rhamnolipids, trehalose lipids, sophorolipids, mannosylerythritol lipids and their traditional producers — the representatives of the genera Pseudozyma, Pseudomonas, Rhodococcus and Candida are given. The detailed analysis of the chemical structure, the stages of the biosynthesis and the regulation of some low molecular glycolipids are done. The own experimental data concerning the synthesis intensification, the physiological role and the practical use of Rhodococcus erythropolis IMV Ac-5017, Acinetobacter calcoaceticus IMV B-7241 and Nocardia vaccinii IMV B-7405 surfactants, which are a complex of the glyco-, phospho-, amino- and neutral lipids (glycolipids of all strains are presented by trehalose mycolates are summarized. It was found that R. erythropolis IMV Ac-5017, A. calcoaceticus IMV B-7241 and N. vaccinii IMV B-7405 surfactants have protective, antimicrobial and antiadhesive properties. It was shown that R. erythropolis IMV Ac-5017, A. calcoaceticus IMV B-7241 and N. vaccinii IMV B-7405 surfactants preparation of cultural liquid intensified the degradation of oil in water due to the activation of the natural petroleum-oxidizing microflora.

Serum and sputum surfactants -A and -D in multidrug-resistant and ...

African Journals Online (AJOL)

Abnormal production and function of surfactants are associated with pulmonary diseases. Also, pulmonary infections alter surfactant metabolism. Due to lack of information on the levels of surfactants A (SP-A) and D (SP-D) in Nigerian tuberculosis (TB) patients, this study assessed these surfactants in both sputum and ...

Photoisomerization of merocyanine 540 in polymer-surfactant ...

Indian Academy of Sciences (India)

Photoisomerization of merocyanine 540 (MC540) in a polymer-surfactant aggregate is studied using picosecond time resolved emission spectroscopy. The aggregate consists of the polymer, poly(vinylpyrrolidone) (PVP) and the surfactant, sodium dodecyl sulphate (SDS). With increase in the concentration of SDS in an ...

Dysfunction of pulmonary surfactant mediated by phospholipid oxidation is cholesterol-dependent.

Science.gov (United States)

Al-Saiedy, Mustafa; Pratt, Ryan; Lai, Patrick; Kerek, Evan; Joyce, Heidi; Prenner, Elmar; Green, Francis; Ling, Chang-Chun; Veldhuizen, Ruud; Ghandorah, Salim; Amrein, Matthias

2018-04-01

Pulmonary surfactant forms a cohesive film at the alveolar air-lung interface, lowering surface tension, and thus reducing the work of breathing and preventing atelectasis. Surfactant function becomes impaired during inflammation due to degradation of the surfactant lipids and proteins by free radicals. In this study, we examine the role of reactive nitrogen (RNS) and oxygen (ROS) species on surfactant function with and without physiological cholesterol levels (5-10%). Surface activity was assessed in vitro in a captive bubble surfactometer (CBS). Surfactant chemistry, monolayer fluidity and thermodynamic behavior were also recorded before and after oxidation. We report that physiologic amounts of cholesterol combined with oxidation results in severe impairment of surfactant function. We also show that surfactant polyunsaturated phospholipids are the most susceptible to oxidative alteration. Membrane thermodynamic experiments showed significant surfactant film stiffening after free radical exposure in the presence of cholesterol. These results point to a previously unappreciated role for cholesterol in amplifying defects in surface activity caused by oxidation of pulmonary surfactant, a finding that may have implications for treating several lung diseases. Copyright © 2018 Elsevier B.V. All rights reserved.

Neutron reflectivity studies of electric field driven structural transformations of surfactants

CERN Document Server

Majewski, J; Burgess, I; Zamlynny, V; Szymanski, G; Lipkowski, J; Satija, S

2002-01-01

We employed electrochemical methods together with in situ neutron reflectometry to describe the aggregation of organic surfactant molecules at a solid-liquid interface. The neutron reflectometry allowed us to determine the surface coverage, thickness, roughness and the relative positions of the aggregates. We found that the applied electric field may be used to reversibly manipulate the architecture of the organic molecules: from uniform monolayers to adsorbed hemi-micelles. These studies are expected to provide a new insight into the roles played by entropic and electrostatic forces in complex fluids or biomaterials. (orig.)

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

Science.gov (United States)

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

2015-08-14

A series of surfactants combining carbohydrate and imidazolium head groups were prepared and investigated on their assembly behavior. The presence of the imidazolium group dominated the interactions of the surfactants, leading to high CMCs and large molecular surface areas, reflected in curved rather than lamellar surfactant assemblies. The carbohydrate, on the other hand, stabilized molecular assemblies slightly and reduced the surface tension of surfactant solutions considerably. A comparative emulsion study discourages the use of pure alkyl imidazolium glycosides owing to reduced assembly stabilities compared with APGs. However, the surfactants are believed to have potential as component in carbohydrate based surfactant mixtures. Copyright © 2015 Elsevier Ltd. All rights reserved.

Adsorption of dissymmetric cationic gemini surfactants at silica/water interface

Science.gov (United States)

Sun, Yuhai; Feng, Yujun; Dong, Hongwei; Chen, Zhi

2007-05-01

Adsorption of a series of cationic gemini surfactants 12-2- m ( m = 8, 12, 16) on the surface of silica was investigated. The critical micelle concentrations, cmcs, of cationic gemini surfactants in the initial solutions and in the supernatants were measured by conductometry and tensiometer. The changes in cmc values indicate that the ion exchanges take place between polar groups of gemini surfactants adsorbed and ions bound on the surface of silica. The adsorption isotherms of cationic gemini surfactants were obtained by a solution depletion method. Based on the driving force, the adsorption includes two steps, one of which is ion exchange, and the other is hydrophobic interaction. In each step, the tendency of surfactant molecules in the solution to form aggregates or to be adsorbed on the silica varies with their structures. The maximum adsorption amount of gemini surfactants on the silica, τmax, decreases as increasing in the length of one alkyl chain, m, from 8, 12 to 16. So the results show that the adsorption behaviors of gemini surfactants are closely related to the dissymmetry of gemini molecules.

Surfactant-Enhanced Benard Convection on an Evaporating Drop

Science.gov (United States)

Nguyen, Van X.; Stebe, Kathleen J.

2001-11-01

Surfactant effects on an evaporating drop are studied experimentally. Using a fluorescent probe, the distribution and surface phase of the surfactant is directly imaged throughout the evaporation process. From these experiments, we identify conditions in which surfactants promote surface tension-driven Benard instabilities in aqueous systems. The drops under study contain finely divided particles, which act as tracers in the flow, and form well-defined patterns after the drop evaporates. Two flow fields have been reported in this system. The first occurs because the contact line becomes pinned by solid particles at the contact line region. In order for the contact line to remain fixed, an outward flow toward the ring results, driving further accumulation at the contact ring. A ‘coffee ring’ of particles is left as residue after the drop evaporates[1]. The second flow is Benard convection, driven by surface tension gradients on the drop[2,3]. In our experiments, an insoluble monolayer of pentadecanoic acid is spread at the interface of a pendant drop. The surface tension is recorded, and the drop is deposited on a well-defined solid substrate. Fluorescent images of the surface phase of the surfactant are recorded as the drop evaporates. The surfactant monolayer assumes a variety of surface states as a function of the area per molecule at the interface: surface gaseous, surface liquid expanded, and surface liquid condensed phases[4]. Depending upon the surface state of the surfactant as the drop evaporates, transitions of residue patterns left by the particles occur, from the coffee ring pattern to Benard cells to irregular patterns, suggesting a strong resistance to outward flow are observed. The occurrence of Benard cells on a surfactant-rich interface occurs when the interface is in LE-LC coexistence. Prior research concerning surfactant effects on this instability predict that surfactants are strongly stabilizing[5]. The mechanisms for this change in behavior

Gemini Surfactant-Modified Activated Carbon for Remediation of Hexavalent Chromium from Water

Directory of Open Access Journals (Sweden)

Yingying Zhou

2018-01-01

Full Text Available Gemini surfactants, with double hydrophilic and hydrophobic groups, offer potentially orders of magnitude greater surface activity compared to similar single unit molecules. A cationic Gemini surfactant (Propyl didodecyldimethylammonium Bromide, PDDDAB and a conventional cationic surfactant (Dodecyltrimethylammonium Bromide, DTAB were used to pre-treat and generate activated carbon. The removal efficiency of the surfactant-modified activated carbon through adsorption of chromium(VI was investigated under controlled laboratory conditions. Fourier-transform infrared spectroscopy (FT-IR and scanning electron microscopy (SEM were used to investigate the surface changes of surfactant-modified activated carbon. The effect of important parameters such as adsorbent dosage, pH, ionic strength and contact time were also investigated. The chromium(VI was adsorbed more significantly on the Gemini surfactant-modified activated carbon than on the conventional surfactant-modified activated carbon. The correlation coefficients show the data best fit the Freundlich model, which confirms the monolayer adsorption of chromium(VI onto Gemini surfactant-modified activated carbon. From this assessment, the surfactant-modified (especially Gemini surfactant-modified activated carbon in this study showed promise for practical applications to treat water pollution.

Method of cement-solidification of radioactive liquid wastes containing surfactant

Energy Technology Data Exchange (ETDEWEB)

Sugimoto, Y; Yusa, H

1979-04-10

Purpose: To provide the subject method comprising the steps of adjusting the concentration of the surfactant to a value less than the predetermined value even when the concentration of the surfactant is high, and rendering the uniaxial compression strength of the cement-solidification body into more than the defined fabrication reference value. Method: To radioactive liquid wastes there are applied means for boiling and heating liquid wastes by addition of sulfuric acid, means for cracking surfactants by the addition of oxidants and means for precipitating and arresting surfactants. After suppressing the hindrance of the cement hydration reaction by surfactants, the radioactive liquid wastes are cement-solidified. (Nakamura, S.).

Enhanced Removal of a Human Norovirus Surrogate from Fresh Vegetables and Fruits by a Combination of Surfactants and Sanitizers▿

Science.gov (United States)

Predmore, Ashley; Li, Jianrong

2011-01-01

Fruits and vegetables are major vehicles for transmission of food-borne enteric viruses since they are easily contaminated at pre- and postharvest stages and they undergo little or no processing. However, commonly used sanitizers are relatively ineffective for removing human norovirus surrogates from fresh produce. In this study, we systematically evaluated the effectiveness of surfactants on removal of a human norovirus surrogate, murine norovirus 1 (MNV-1), from fresh produce. We showed that a panel of surfactants, including sodium dodecyl sulfate (SDS), Nonidet P-40 (NP-40), Triton X-100, and polysorbates, significantly enhanced the removal of viruses from fresh fruits and vegetables. While tap water alone and chlorine solution (200 ppm) gave only <1.2-log reductions in virus titer in all fresh produce, a solution containing 50 ppm of surfactant was able to achieve a 3-log reduction in virus titer in strawberries and an approximately 2-log reduction in virus titer in lettuce, cabbage, and raspberries. Moreover, a reduction of approximately 3 logs was observed in all the tested fresh produce after sanitization with a solution containing a combination of 50 ppm of each surfactant and 200 ppm of chlorine. Taken together, our results demonstrate that the combination of a surfactant with a commonly used sanitizer enhanced the efficiency in removing viruses from fresh produce by approximately 100 times. Since SDS is an FDA-approved food additive and polysorbates are recognized by the FDA as GRAS (generally recognized as safe) products, implementation of this novel sanitization strategy would be a feasible approach for efficient reduction of the virus load in fresh produce. PMID:21622782

Controlling block copolymer phase behavior using ionic surfactant

Energy Technology Data Exchange (ETDEWEB)

Ray, D.; Aswal, V. K. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India E-mail: debes.phys@gmail.com (India)

2016-05-23

The phase behavior of poly(ethylene oxide)-poly(propylene oxide-poly(ethylene oxide) PEO-PPO-PEO triblock copolymer [P85 (EO{sub 26}PO{sub 39}EO{sub 26})] in presence of anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solution as a function of temperature has been studied using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations (1 wt%) of block copolymer and surfactants. Each of the individual components (block copolymer and surfactant) and the nanoparticle–surfactant mixed system have been examined at varying temperature. The block copolymer P85 forms spherical micelles at room temperature whereas shows sphere-to-rod like micelle transition at higher temperatures. On the other hand, SDS surfactant forms ellipsoidal micelles over a wide temperature range. Interestingly, it is found that phase behavior of mixed micellar system (P85 + SDS) as a function of temperature is drastically different from that of P85, giving the control over the temperature-dependent phase behavior of block copolymers.

Aerobic biodegradation of amphoteric amine-oxide-based surfactants: Effect of molecular structure, initial surfactant concentration and pH.

Science.gov (United States)

Ríos, Francisco; Lechuga, Manuela; Fernández-Serrano, Mercedes; Fernández-Arteaga, Alejandro

2017-03-01

The present study was designed to provide information regarding the effect of the molecular structure of amphoteric amine-oxide-based surfactants and the initial surfactant concentration on their ultimate biodegradation. Moreover, given this parameter's pH-dependence, the effect of pH was also investigated. Three amine-oxide-based surfactants with structural differences in their hydrophobic alkyl chain were tested: Lauramine oxide (AO-R 12 ), Myristamine oxide (AO-R 14 ) and Cocamidopropylamine oxide (AO-Cocoamido). We studied the ultimate biodegradation using the Modified OECD Screening Test at initial surfactant concentrations ranged from 5 to 75 mg L -1 and at pH levels from 5 to 7.4. The results demonstrate that at pH 7.4, amine-oxide-based surfactants are readily biodegradable. In this study, we concluded that ω-oxidation can be assumed to be the main biodegradation pathway of amine-oxides and that differences in the biodegradability between them can be explained by the presence of an amide group in the alkyl chain of AO-Cocoamido; the CN fission of the amide group slows down their mineralization process. In addition, the increase in the concentration of the surfactant from 5 to 75 mg L -1 resulted in an increase in the final biodegradation of AO-R 12 and AO-R 14 . However, in the case of AO-Cocoamido, a clear relationship between the concentration and biodegradation cannot be stated. Conversely, the biodegradability of AO-R 12 and AO-R 14 was considerably lower in an acid condition than at a pH of 7.4, whereas AO-Cocoamido reached similar percentages in acid conditions and at a neutral pH. However, microorganisms required more time to acclimate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Toxicological assessment of four common household surfactants on ...

African Journals Online (AJOL)

The acute toxicity of four common household liquid detergents coded as (FL, ML, MF and LC) was evaluated on two fish species; African Catfish (Clarias gariepinus) and Nile Tilapia (Oreochromis niloticus) fingerlings in a static bioassay. During the exposure period (96 hours), there was a remarkable rise of alkalinity from ...

Laser-heating-induced displacement of surfactants on the water surface

NARCIS (Netherlands)

Backus, E.H.G.; Bonn, D.; Cantin, S.; Roke, S.; Bonn, M.

2012-01-01

We report a combined vibrational sum-frequency generation (SFG) spectroscopy, Brewster angle microscopy (BAM), and ellipsometry study of different surfactants on water as a function of surfactant density. Vibrational SFG spectra of surfactants on the water surface in a Langmuir trough have been

Molecular-thermodynamic theory of micellization of pH-sensitive surfactants.

Science.gov (United States)

Goldsipe, Arthur; Blankschtein, Daniel

2006-04-11

A predictive, molecular-thermodynamic theory is developed to model the micellization of pH-sensitive surfactants. The theory combines a molecular-thermodynamic description of micellization in binary surfactant mixtures with the protonation equilibrium of the surfactant monomers. The thermodynamic component of the theory models the pH-mediated equilibrium between micelles, surfactant monomers, and counterions. These counterions may originate from the surfactant or from added salt, acid, or base. The molecular component of the theory models the various contributions to the free energy of micellization, which corresponds to the free-energy change associated with forming a mixed micelle from the protonated and deprotonated forms of the surfactant and from the bound counterions. The free energy of micellization includes hydrophobic, interfacial, packing, steric, electrostatic, and entropic contributions, which are all calculated molecularly. The theory also requires knowledge of the surfactant molecular structure and the solution conditions, including the temperature and the amount of any added salt, acid, or base. To account for the pH sensitivity of the surfactant, the theory requires knowledge of the surfactant monomer equilibrium deprotonation constant (pK1), which may be obtained from experimental titration data obtained below the critical micelle concentration (cmc). The theory can be utilized to predict the equilibrium micelle and solution properties, including the cmc, the micelle composition, the micelle shape and aggregation number, the solution pH, and the micelle deprotonation equilibrium constant (pKm). Theoretical predictions of the cmc, the micelle aggregation number, and the pKm compare favorably with the available experimental data for alkyldimethylamine oxide surfactants. This class of pH-sensitive surfactants exhibits a form of self-synergy, which has previously been attributed to hydrogen-bond formation at the micelle interface. Instead, we show that

Viscosity and sedimentation behaviors of the magnetorheological suspensions with oleic acid/dimer acid as surfactants

Energy Technology Data Exchange (ETDEWEB)

Yang, Jianjian; Yan, Hua; Hu, Zhide; Ding, Ding

2016-11-01

This work deals with the role of polar interactions on the viscosity and sedimentation behaviors of magnetorheological suspensions with micro-sized magnetic particles dispersed in oil carriers. The oleic acid and dimer acid were employed to make an adjustment of the hydrophobicity of iron particles, in the interest of performing a comparative evaluation of the contributions of the surface polarity. The viscosity tests show that the adsorbed surfactant layer may impose a hindrance to the movement of iron particles in the oil medium. The polar attractions between dimer acid covered particles gave rise to a considerable increase in viscosity, indicating flocculation structure developed in the suspensions. The observed plateau-like region in the vicinity of 0.1 s{sup −1} for MRF containing dimer acid is possibly due to the flocculation provoked by the carboxylic polar attraction, in which the structure is stable against fragmentation. Moreover, a quick recovery of the viscosity and a higher viscosity-temperature index also suggest the existence of particle-particle polar interaction in the suspensions containing dimer acid. The sedimentation measurements reveal that the steric repulsion of oleic acid plays a limited role in the stability of suspensions only if a large quantity of surfactant was used. The sedimentation results observed in the dimer acid covered particles confirm that loose and open flocculation was formed and enhanced sedimentation stability. - Highlights: • Surfactants were employed to make adjustments of the hydrophobicity of particles. • Polar attractions between particles increased the viscosity considerably. • Loose and open flocculation was formed in CI/DA suspension. • The steric repulsion of oleic acid played a limited role in the stability.

Lateral transport of solutes in microfluidic channels using electrochemically generated gradients in redox-active surfactants.

Science.gov (United States)

Liu, Xiaoyang; Abbott, Nicholas L

2011-04-15

We report principles for a continuous flow process that can separate solutes based on a driving force for selective transport that is generated by a lateral concentration gradient of a redox-active surfactant across a microfluidic channel. Microfluidic channels fabricated with gold electrodes lining each vertical wall were used to electrochemically generate concentration gradients of the redox-active surfactant 11-ferrocenylundecyl-trimethylammonium bromide (FTMA) in a direction perpendicular to the flow. The interactions of three solutes (a hydrophobic dye, 1-phenylazo-2-naphthylamine (yellow AB), an amphiphilic molecule, 2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1-hexadecanoyl-sn-glycero-3-phosphocholine (BODIPY C(5)-HPC), and an organic salt, 1-methylpyridinium-3-sulfonate (MPS)) with the lateral gradients in surfactant/micelle concentration were shown to drive the formation of solute-specific concentration gradients. Two distinct physical mechanisms were identified to lead to the solute concentration gradients: solubilization of solutes by micelles and differential adsorption of the solutes onto the walls of the microchannels in the presence of the surfactant concentration gradient. These two mechanisms were used to demonstrate delipidation of a mixture of BODIPY C(5)-HPC (lipid) and MPS and purification of BODIPY C(5)-HPC from a mixture of BODIPY C(5)-HPC and yellow AB. Overall, the results of this study demonstrate that lateral concentration gradients of redox-active surfactants formed within microfluidic channels can be used to transport solutes across the microfluidic channels in a solute-dependent manner. The approach employs electrical potentials (solutions having high ionic strength (>0.1M), and offers the basis of continuous processes for the purification or separation of solutes in microscale systems. © 2011 American Chemical Society

A multicenter, randomized trial comparing synthetic surfactant with modified bovine surfactant extract in the treatment of neonatal respiratory distress syndrome

NARCIS (Netherlands)

Adams, E; Vollman, J; Giebner, D; Maurer, M; Dreyer, G; Bailey, L; Anderson, M; Mefford, L; Beaumont, E; Sutton, D; Puppala, B; Mangurten, HH; Secrest, J; Lewis, WJ; Carteaux, P; Bednarek, F; Welsberger, S; Gosselin, R; Pantoja, AF; Belenky, A; Campbell, P; Patole, S; Duenas, M; Kelly, M; Alejo, W; Lewallen, P; DeanLieber, S; Hanft, M; Ferlauto, J; Newell, RW; Bagwell, J; Levine, D; Lipp, RW; Harkavy, K; Vasa, R; Birenbaum, H; Broderick, KA; Santos, AQ; Long, BA; Gulrajani, M; Stern, M; Hopgood, G; Hegyi, T; Alba, J; Christmas, L; McQueen, M; Nichols, N; Brown, M; Quissell, BJ; Rusk, C; Marks, K; Gifford, K; Hoehn, G; Pathak, A; Marino, B; Hunt, P; Fox, [No Value; Sharpstein, C; Feldman, B; Johnson, N; Beecham, J; Balcom, R; Helmuth, W; Boylan, D; Frakes, C; Magoon, M; Reese, K; Schwersenski, J; Schutzman, D; Soll, R; Horbar, JD; Leahy, K; Troyer, W; Juzwicki, C; Anderson, P; Dworsky, M; Reynolds, L; Urrutia, J; Gupta, U; Adray, C

Objective. To compare the efficacy of a synthetic surfactant (Exosurf Neonatal, Burroughs-Wellcome Co) and a modified bovine surfactant extract (Survanta, Ross Laboratories) in the treatment of neonatal respiratory distress syndrome (RDS). Design. Multicenter, randomized trial. Setting. Thirty-eight

Early surfactant therapy and nasal continuous positive airways ...

African Journals Online (AJOL)

respiratory distress syndrome (RDS) receiving nasal continuous positive airways ... required FiO2 was allowed to rise above 0.4 before surfactant was administered. ... group received surfactant immediately and the high-threshold group ...

A novel biosensor method for surfactant determination based on acetylcholinesterase inhibition

International Nuclear Information System (INIS)

Kucherenko, I S; Soldatkin, O O; Arkhypova, V M; Dzyadevych, S V; Soldatkin, A P

2012-01-01

A novel enzyme biosensor based on acetylcholinesterase inhibition for the determination of surfactants in aqueous solutions is described. Acetylcholinesterase-based bioselective element was deposited via glutaraldehyde on the surface of conductometric transducers. Different variants of inhibitory analysis of surfactants were tested, and finally surfactant's concentration was evaluated by measuring initial rate of acetylcholinesterase inhibition. Besides, we studied the effect of solution characteristics on working parameters of the biosensor for direct measurement of acetylcholine and for inhibitory determination of surfactants. The biosensor's sensitivity to anionic and cationic surfactants (0.35 mg l −1 ) was tested. The high operational stability of the biosensor during determination of acetylcholine (RSD 2%) and surfactants (RSD 11%) was shown. Finally, we discussed the selectivity of the biosensor toward surfactants and other AChE inhibitors. The proposed biosensor can be used as a component of the multibiosensor for ecological monitoring of toxicants. (paper)

Effect of surfactant types and their concentration on the structural characteristics of nanoclay

Science.gov (United States)

Zawrah, M. F.; Khattab, R. M.; Saad, E. M.; Gado, R. A.

2014-03-01

A series of organo-modified nanoclays was synthesized using three different surfactants having different alkyl chain lengths and concentrations [0.5-5.0 cation exchange capacity (CEC)]. These surfactants were Ethanolamine (EA), Cetyltrimethylammoniumbromide (CTAB) and Tetraoctadecylammoniumbromide (TO). The obtained modified nanoclays were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) and compared with unmodified nanoclay. The results of XRD analysis indicated that the basal d-spacing has increased with increasing alkyl chain length and surfactant concentration. From the obtained microstructures of these organo-modified nanoclays, the mechanism of surfactant adsorption was proposed. At relatively low loading of surfactant, most of surfactant entered the spacing by an ion-exchange mechanism and is adsorbed onto the interlayer cation sites. When the concentration of the surfactant exceeds the CEC of clay, the surfactant molecules then adhere to the surface adsorbed surfactant. Some surfactants entered the interlayers, whereas the others were attached to the clay surface. When the concentration of surfactant increased further beyond 2.0 CEC, the surfactants might occupy the inter-particle space within the house-of-cards aggregate structure.

Nanoparticle decoration with surfactants: Molecular interactions, assembly, and applications

Science.gov (United States)

Heinz, Hendrik; Pramanik, Chandrani; Heinz, Ozge; Ding, Yifu; Mishra, Ratan K.; Marchon, Delphine; Flatt, Robert J.; Estrela-Lopis, Irina; Llop, Jordi; Moya, Sergio; Ziolo, Ronald F.

2017-02-01

Nanostructures of diverse chemical nature are used as biomarkers, therapeutics, catalysts, and structural reinforcements. The decoration with surfactants has a long history and is essential to introduce specific functions. The definition of surfactants in this review is very broad, following its lexical meaning ;surface active agents;, and therefore includes traditional alkyl modifiers, biological ligands, polymers, and other surface active molecules. The review systematically covers covalent and non-covalent interactions of such surfactants with various types of nanomaterials, including metals, oxides, layered materials, and polymers as well as their applications. The major themes are (i) molecular recognition and noncovalent assembly mechanisms of surfactants on the nanoparticle and nanocrystal surfaces, (ii) covalent grafting techniques and multi-step surface modification, (iii) dispersion properties and surface reactions, (iv) the use of surfactants to influence crystal growth, as well as (v) the incorporation of biorecognition and other material-targeting functionality. For the diverse materials classes, similarities and differences in surfactant assembly, function, as well as materials performance in specific applications are described in a comparative way. Major factors that lead to differentiation are the surface energy, surface chemistry and pH sensitivity, as well as the degree of surface regularity and defects in the nanoparticle cores and in the surfactant shell. The review covers a broad range of surface modifications and applications in biological recognition and therapeutics, sensors, nanomaterials for catalysis, energy conversion and storage, the dispersion properties of nanoparticles in structural composites and cement, as well as purification systems and classical detergents. Design principles for surfactants to optimize the performance of specific nanostructures are discussed. The review concludes with challenges and opportunities.

Evaluation of the interaction of surfactants with stratum corneum model membrane from Bothrops jararaca by DSC.

Science.gov (United States)

Baby, André Rolim; Lacerda, Aurea Cristina Lemos; Velasco, Maria Valéria Robles; Lopes, Patrícia Santos; Kawano, Yoshio; Kaneko, Telma Mary

2006-07-06

The interaction of surfactants sodium dodecyl sulfate (SDS), cetyl trimethyl ammonium chloride (CTAC) and lauryl alcohol ethoxylated (12 mol ethylene oxide) (LAE-12OE) was evaluated on the stratum corneum (SC) of shed snake skins from Bothrops jararaca, used as model membrane, and thermal characterized by differential scanning calorimetry (DSC). Surfactant solutions were employed above of the critical micellar concentration (CMC) with treatment time of 8h. The SDS interaction with the SC model membrane has increased the characteristic transition temperature of 130 degrees C in approximately 10 degrees C for the water loss and keratin denaturation, indicating an augmentation of the water content. Samples treated with CTAC have a decrease of the water loss temperature, while, for the LAE-12OE treated samples, changes on the transition temperature have not been observed.

Gemini (dimeric) Surfactants

Indian Academy of Sciences (India)

is in turn bonded to an identical hydrocarbon tail; alternatively,. ~. Tail spacer ... formed is dependent on surfactant structure, temperature, ionic strength and pH. The models of GS are .... micelle to the air/water interface. Moreover, GS can be ...

The impact of alkyl sulfate surfactant geometry and electrolyte on the co-adsorption of anionic surfactants with model perfumes at the air-solution interface.

Science.gov (United States)

Bradbury, Robert; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Jones, Craig

2013-08-01

The impact of surfactant geometry and electrolyte on the co-adsorption of anionic surfactants and model perfumes at the air-solution interface has been studied by neutron reflectivity. The more hydrophobic perfume linalool, competes more favourably for the surface with sodium dodecylsulfate than was previously reported for the anionic surfactant, sodium dodecyl 6-benzenesulfonate. Due to an increase in surface activity of the sodium dodecylsulfate, the addition of electrolyte results in a reduction in the linalool adsorption. Changing the alkyl chain length affects the relative adsorption of linalool and surfactant at the interface. Similar measurements for the different alkyl sulfates and with electrolyte with the more hydrophilic perfume phenyl ethanol, reveal broadly similar trends. Although the relative adsorption of phenyl ethanol with sodium dodecylsulfate is substantially enhanced compared to sodium dodecyl-6-benzenesulfonate the effects are not as significant as was observed with linalool. The variations with alkyl chain geometry show the importance of the hydrophobic interaction between the perfume and surfactant and changes in the packing constraints on the relative adsorption. The results highlight the importance of the specific interaction between the surfactant and perfume, and the surfactant and perfume geometries on the relative adsorption at the interface. Copyright © 2013 Elsevier Inc. All rights reserved.

Lung Surfactant Microbubbles Increase Lipophilic Drug Payload for Ultrasound-Targeted Delivery

OpenAIRE

Sirsi, Shashank R.; Fung, Chinpong; Garg, Sumit; Tianning, Mary Y.; Mountford, Paul A.; Borden, Mark A.

2013-01-01

The cavitation response of circulating microbubbles to targeted ultrasound can be used for noninvasive, site-specific delivery of shell-loaded materials. One challenge for microbubble-mediated delivery of lipophilic compounds is the limitation of drug loading into the microbubble shell, which is commonly a single phospholipid monolayer. In this study, we investigated the use of natural lung surfactant extract (Survanta?, Abbott Nutrition) as a microbubble shell material in order to improve dr...

Micellar solubilization in strongly interacting binary surfactant systems. [Binary surfactant systems of: dodecyltrimethylammonium chloride + sodium dodecyl sulfate; benzyldimethyltetradecylammonium chloride + tetradecyltrimethylammonium chloride

Energy Technology Data Exchange (ETDEWEB)

Treiner, C. (Universite Pierre et Marie Curie, Paris (France)); Nortz, M.; Vaution, C. (Faculte de Pharmacie de Paris-sud, Chatenay-Malabry (France))

1990-07-01

The apparent partition coefficient P of barbituric acids between micelles and water has been determined in mixed binary surfactant solutions from solubility measurements in the whole micellar composition range. The binary systems chosen ranged from the strongly interacting system dodecyltrimethylammonium chloride + sodium dodecyl sulfate to weakly interacting systems such as benzyldimethyltetradecylammonium chloride + tetradecyltrimethyammonium chloride. In all cases studied, mixed micelle formation is unfavorable to micellar solubilization. A correlation is found between the unlike surfactants interaction energy, as measured by the regular solution parameter {beta} and the solute partition coefficient change upon surfactant mixing. By use of literature data on micellar solubilization in binary surfactant solutions, it is shown that the change of P for solutes which are solubilized by surface adsorption is generally governed by the sign and amplitude of the interaction parameter {beta}.

Biodegradability of bacterial surfactants.

Science.gov (United States)

Lima, Tânia M S; Procópio, Lorena C; Brandão, Felipe D; Carvalho, André M X; Tótola, Marcos R; Borges, Arnaldo C

2011-06-01

This work aimed at evaluating the biodegradability of different bacterial surfactants in liquid medium and in soil microcosms. The biodegradability of biosurfactants by pure and mixed bacterial cultures was evaluated through CO(2) evolution. Three bacterial strains, Acinetobacter baumanni LBBMA ES11, Acinetobacter haemolyticus LBBMA 53 and Pseudomonas sp. LBBMA 101B, used the biosurfactants produced by Bacillus sp. LBBMA 111A (mixed lipopeptide), Bacillus subtilis LBBMA 155 (lipopeptide), Flavobacterium sp. LBBMA 168 (mixture of flavolipids), Dietzia Maris LBBMA 191(glycolipid) and Arthrobacter oxydans LBBMA 201(lipopeptide) as carbon sources in minimal medium. The synthetic surfactant sodium dodecyl sulfate (SDS) was also mineralized by these microorganisms, but at a lower rate. CO(2) emitted by a mixed bacterial culture in soil microcosms with biosurfactants was higher than in the microcosm containing SDS. Biosurfactant mineralization in soil was confirmed by the increase in surface tension of the soil aqueous extracts after incubation with the mixed bacterial culture. It can be concluded that, in terms of biodegradability and environmental security, these compounds are more suitable for applications in remediation technologies in comparison to synthetic surfactants. However, more information is needed on structure of biosurfactants, their interaction with soil and contaminants and scale up and cost for biosurfactant production.

Pyrene removal from contaminated soil using electrokinetic process combined with surfactant

Directory of Open Access Journals (Sweden)

Seyed Enayat Hashemi

2015-07-01

Full Text Available Background: Pyrene is one of the stable polycyclic aromatic hydrocarbons that is considered as an important pollutants, because of extensive distribution in the environment and carcinogenic and mutagenic properties. Among the various treatment techniques, electrokinetic method is an environmental- friendly process for organic and mineral pollutants adsorbed to soil with fine pore size the same as clay and low hydraulic conductivity soils. For improving the efficiency of pyrene removal from soil, soulobilization of pyrene from soil could be used by surfactants. Materials and Methods : In this study, clay soil was selected as model because of the specific properties. Combined method using surfactant and electrokinetic was applied for pyrene removal from soil. Experiments were designed using response surface methodology (RSM, and effect of three variables includes surfactant concentration, voltage and surfactant type were evaluated for pyrene removal from contaminated soil. Results: Pyrene removal using anionic surfactants(SDS and nonionic surfactants(TX100 as a solubilizing agents has high removal efficiency. In the optimum condition with 95% confidence coefficient, utilizing mixed surfactants of sodium dodecyl sulfate and triton X-100 with the same volume, induced of 18.54 volt and 6.53 percent surfactant concentration have 94.6% pyrene removal efficiency. Conclusion:: Results of this study shows that electrokinetic process combined with surfactant as solubilizing agent could be applied as an efficient method for treating the pyrene-contaminated soils.

Enhanced Oil Recovery with Surfactant Flooding

DEFF Research Database (Denmark)

Sandersen, Sara Bülow

, thus reducing the interfacial tension (IFT) to ultra low (0.001 mN/m), which consequently will mobilize the residual oil and result in improved oil recovery. This EOR technology is, however, made challenging by a number of factors, such as the adsorption of surfactant and co-surfactant to the rock...... be resistant to and remain active at reservoir conditions such as high temperatures, pressures and salinities. Understanding the underlying mechanisms of systems that exhibit liquid-liquid equilibrium (e.g. oil-brine systems) at reservoir conditions is an area of increasing interest within EOR. This is true...... studied. The effect of increased pressure became more significant when combined with increasing temperature. The experiments performed on the oil/ seawater systems were similar to the high pressure experiments for the surfactant system discussed above. Oil was contacted with different brine solutions...

LOWER COST METHODS FOR IMPROVED OIL RECOVERY (IOR) VIA SURFACTANT FLOODING

Energy Technology Data Exchange (ETDEWEB)

William A. Goddard III; Yongchun Tang; Patrick Shuler; Mario Blanco; Seung Soon Jang; Shiang-Tai Lin; Prabal Maiti; Yongfu Wu; Stefan Iglauer; Xiaohang Zhang

2004-09-01

This report provides a summary of the work performed in this 3-year project sponsored by DOE. The overall objective of this project is to identify new, potentially more cost-effective surfactant formulations for improved oil recovery (IOR). The general approach is to use an integrated experimental and computational chemistry effort to improve our understanding of the link between surfactant structure and performance, and from this knowledge, develop improved IOR surfactant formulations. Accomplishments for the project include: (1) completion of a literature review to assemble current and new surfactant IOR ideas, (2) Development of new atomistic-level MD (molecular dynamic) modeling methodologies to calculate IFT (interfacial tension) rigorously from first principles, (3) exploration of less computationally intensive mesoscale methods to estimate IFT, Quantitative Structure Property Relationship (QSPR), and cohesive energy density (CED) calculations, (4) experiments to screen many surfactant structures for desirable low IFT and solid adsorption behavior, and (5) further experimental characterization of the more promising new candidate formulations (based on alkyl polyglycosides (APG) and alkyl propoxy sulfate surfactants). Important findings from this project include: (1) the IFT between two pure substances may be calculated quantitatively from fundamental principles using Molecular Dynamics, the same approach can provide qualitative results for ternary systems containing a surfactant, (2) low concentrations of alkyl polyglycoside surfactants have potential for IOR (Improved Oil Recovery) applications from a technical standpoint (if formulated properly with a cosurfactant, they can create a low IFT at low concentration) and also are viable economically as they are available commercially, and (3) the alkylpropoxy sulfate surfactants have promising IFT performance also, plus these surfactants can have high optimal salinity and so may be attractive for use in higher

Surfactant-enhanced recovery of dissolved hydrocarbons at petroleum production facilities

International Nuclear Information System (INIS)

Freeman, J.T.; Mayes, M.; Wassmuth, F.; Taylor, K.; Rae, W.; Kuipers, F.

1997-01-01

The feasibility and cost effectiveness of surfactant-enhanced pumping to reduce source concentrations of petroleum hydrocarbons from contaminated soils was discussed. Light non-aqueous phase liquids (LNAPL) hydrocarbons are present beneath many petroleum production processing facilities in western Canada. Complete removal of LNAPLs from geologic materials is difficult and expensive. Treatment technologies include costly ex-situ methods such as excavation and in-situ methods such as physical extraction by soil venting and pumping, bioremediation, and combination methods such as bioventing, bioslurping or air sparging. Surfactant-aided pumping can reduce source hydrocarbon concentrations when used in conjunction with traditional pump and treat, or deep well injection. This study involved the selection of an appropriate surfactant from a wide variety of commercially available products. A site contaminated by hydrocarbons in Turner Valley, Alberta, was used for field scale testing. One of the major problems was quantifying the increase in the dissolved hydrocarbon concentrations in the recovered water once a surfactant was added. From the 30 surfactants screened in a series of washing and oil solubilization tests, two surfactants, Brij 97 and Tween 80, were selected for further evaluation. Increased hydrocarbon recovery was observed within 10 days of the introduction of the first surfactant. 2 refs., 7 figs

Contribution of Seawater Surfactants to Generated Primary Marine Aerosol Particles

Science.gov (United States)

Frossard, A. A.; Gerard, V.; Duplessis, P.; Kinsey, J. D.; Lu, X.; Zhu, Y.; Bisgrove, J.; Maben, J. R.; Long, M. S.; Chang, R.; Beaupre, S. R.; Kieber, D. J.; Keene, W. C.; Noziere, B.; Cohen, R. C.

2017-12-01

Surfactants account for minor fractions of total organic carbon in the ocean but may have major impacts on the surface tension of bursting bubbles at the sea surface that drive the production of primary marine aerosol particles (PMA). Surfactants associated with marine aerosol may also significantly reduce the surface tension of water thereby increasing the potential for cloud droplet activation and growth. During September and October 2016, PMA were produced from bursting bubbles in seawater using a high capacity generator at two biologically productive and two oligotrophic stations in the western North Atlantic, as part of a cruise on the R/V Endeavor. Surfactants were extracted from paired PMA and seawater samples, and their ionic compositions, total concentrations, and critical micelle concentrations (CMC) were quantified and compared for the four hydrographic stations. Higher surfactant concentrations were determined in the aerosol produced from biologically productive seawater compared to oligotrophic seawater, and the surfactants extracted from productive seawater were stronger (had lower CMCs) than those in the oligotrophic seawater. Surfactants associated with PMA and seawater in productive regions also varied over diel cycles, whereas those in the oligotrophic regions did not. This work demonstrates a direct link between surfactants in seawater and those in PMA.

Adsorption of surfactants and polymers at interfaces

Science.gov (United States)

Rojas, Orlando Jose

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

Nonlinear vibrational spectroscopy of surfactants at liquid interfaces

Science.gov (United States)

Miranda, Paulo Barbeitas

Surfactants are widely used to modify physical and chemical properties of interfaces. They play an important role in many technological problems. Surfactant monolayers are also of great scientific interest because they are two-dimensional systems that may exhibit a very rich phase transition behavior and can also be considered as a model system for biological interfaces. In this Thesis, we use a second-order nonlinear optical technique (Sum-Frequency Generation - SFG) to obtain vibrational spectra of surfactant monolayers at liquid/vapor and solid/liquid interfaces. The technique has several advantages: it is intrinsically surface-specific, can be applied to buried interfaces, has submonolayer sensitivity and is remarkably sensitive to the conformational order of surfactant monolayers. The first part of the Thesis is concerned with surfactant monolayers at the air/water interface (Langmuir films). Surface crystallization of an alcohol Langmuir film and of liquid alkanes are studied and their phase transition behaviors are found to be of different nature, although driven by similar intermolecular interactions. The effect of crystalline order of Langmuir monolayers on the interfacial water structure is also investigated. It is shown that water forms a well-ordered hydrogen-bonded network underneath an alcohol monolayer, in contrast to a fatty acid monolayer which induces a more disordered structure. In the latter case, ionization of the monolayer becomes more significant with increase of the water pH value, leading to an electric-field-induced ordering of interfacial water molecules. We also show that the orientation and conformation of fairly complicated molecules in a Langmuir monolayer can be completely mapped out using a combination of SFG and second harmonic generation (SHG). For a quantitative analysis of molecular orientation at an interface, local-field corrections must be included. The second part is a study of self-assembled surfactant monolayers at the

Respiratory Mechanics and Gas Exchange: The Effect of Surfactants

Science.gov (United States)

Jbaily, Abdulrahman; Szeri, Andrew J.

2017-11-01

The purpose of the lung is to exchange gases, primarily oxygen and carbon dioxide, between the atmosphere and the circulatory system. To enable this exchange, the airways in the lungs terminate in some 300 million alveoli that provide adequate surface area for transport. During breathing, work must be done to stretch various tissues to accommodate a greater volume of gas. Considerable work must also be done to expand the liquid lining (hypophase) that coats the interior surfaces of the alveoli. This is enabled by a surface active lipo-protein complex, known as pulmonary surfactant, that modifies the surface tension at the hypophase-air interface. Surfactants also serve as physical barriers that modify the rate of gas transfer across interfaces. We develop a mathematical model to study the action of pulmonary surfactant and its determinative contributions to breathing. The model is used to explore the influence of surfactants on alveolar mechanics and on gas exchange: it relates the work of respiration at the level of the alveolus to the gas exchange rate through the changing influence of pulmonary surfactant over the breathing cycle. This work is motivated by a need to develop improved surfactant replacement therapies to treat serious medical conditions.

Occurrence of multi-class surfactants in urban wastewater: contribution of a healthcare facility to the pollution transported into the sewerage system.

Science.gov (United States)

Bergé, Alexandre; Wiest, Laure; Baudot, Robert; Giroud, Barbara; Vulliet, Emmanuelle

2018-04-01

Healthcare facility discharges, by their nature, are often considered as non-domestic effluent, which can provide significant pollution comparatively to other domestic sources. In this context, a total of 12 monthly sampling campaigns were collected from a healthcare facility as well as the output of a sewerage system of Site Pilote de Bellecombe (SIPIBEL) observatory. This study focuses more specifically on 12 surfactants and biocides: four anionics, four cationic, two non-ionic, one zwitterionic, and one dispersive agent, among the most commonly used commercial surfactants. Particular attention was also provided to routine wastewater quality parameters. Both effluents were heavily contaminated by most anionic surfactants; they displayed median concentrations up to 1 to 2 mg/L for linear alkylbenzene sulfonates and between 10 and 100 μg/L for other sodium sulfate congeners (lauryl and laureth). Overall, for the majority of surfactants, the healthcare facility contribution to the total flux reaching the wastewater treatment plant ranges between 5 and 9%.

Survival, mobility, and membrane-bound enzyme activities of freshwater planarian, Dugesia japonica, exposed to synthetic and natural surfactants.

Science.gov (United States)

Li, Mei-Hui

2012-04-01

Surfactants are a major class of emerging pollutants widely used in large quantities in everyday life and commonly found in surface waters worldwide. Freshwater planarian was selected to examine the effects of different surfactants by measuring mortality, mobility, and membrane-bound enzyme activities. Among the 10 surfactants tested, the acute toxicities of betaine and polyethylene glycol (PEG-200) to planarians were relatively low, with a median lethal concentration (LC50) greater than 10,000 mg/L. The toxicity to planarians of the other eight surfactants based on 48-h LC50 could be arranged in the descending order of cetylpyridinum chloride (CPC) > 4-tert-octylphenol (4-tert-OP) > ammonium lauryl sulfate > benzalkonium chloride > saponin > sodium lauroylsarcosinate > dioctyl sulfosuccinate > dodecyl trimethyl ammonium bromide (DTAB). Both CPC and 4-tert-OP were very toxic to planarians, with 48-h LC50 values <1 mg/L. The median effective concentrations (EC50s) of planarian mobility were in the 0.1 to 50 mg/L range and were in the same range as the 24-h LC50 of planarians exposed to different surfactants, except for DTAB. In addition, significant inhibition of cholinesterase activity activities was found in planarians exposed to 4-tert-OP at 2.5 and 5 mg/L and to saponin at 10 mg/L after 2-h treatments. This result suggests that planarian mobility responses can be used as an alternative indicator for acute toxicity of surfactants after a very short exposure period. Copyright © 2012 SETAC.

Marangoni flows induced by non-uniform surfactant distributions

NARCIS (Netherlands)

Hanyak, M.

2012-01-01

The spreading dynamics of surfactants is of crucial importance for numerous technological applications ranging from printing and coating processes, pulmonary drug delivery to crude oil recovery. In the area of inkjet printing surfactants are necessary for lowering surface tension of water-based ink

Polymeric surfactants for enhanced oil recovery : A review

NARCIS (Netherlands)

Raffa, Patrizio; Broekhuis, Antonius A.; Picchioni, Francesco

Chemical enhanced oil recovery (EOR) is surely a topic of interest, as conventional oil resources become more scarce and the necessity of exploiting heavy and unconventional oils increases. EOR methods based on polymer flooding, surfactant-polymer flooding and alkali-surfactant-polymer flooding are

Reaction limited aggregation in surfactant-mediated epitaxy

Science.gov (United States)

Wu, Jing; Liu, Bang-Gui; Zhang, Zhenyu; Wang, E. G.

2000-05-01

A theoretical model for reaction limited aggregation (RLA) is introduced to study the effect of a monolayer of surfactant on the formation of two-dimensional islands in heteroepitaxial and homoepitaxial growth. In this model the basic atomic processes are considered as follows. A stable island consists of the adatoms that have exchanged positions with the surfactant atoms beneath them. Movable active adatoms may (a) diffuse on the surfactant terrace, (b) exchange positions with the surfactant atoms beneath them and become island seeds (seed exchange), or (c) stick to stable islands and become stuck but still active adatoms. The rate-limiting step for the formation of a stable island is the seed exchange. Furthermore, a stuck but still active adatom must overcome a sizable potential-energy barrier to exchange positions with the surfactant atom beneath it and become a member of the stable island (aided exchange). The seed exchange process can occur with an adatom or collectively with an addimer. In the case of dimer exchange, the diffusing adatoms on the surfactant terrace can meet and (after exchanging) form stable dimers, which can then become island seeds. Systematic kinetic Monte Carlo simulations and rate-equation analysis of the model are carried out. The key finding of these simulations is that a counterintuitive fractal-to-compact island shape transition can be induced either by increasing deposition flux or by decreasing growth temperature. This major qualitative conclusion is valid for both the monomer and the dimer seed exchanges and for two different substrate lattices (square and triangular, respectively), although there are some quantitative differences in the flux and temperature dependence of the island density. The shape transition observed is contrary to the prediction of the classic diffusion-limited aggregation (DLA) theory, but in excellent qualitative agreement with recent experiments. In rationalizing the main finding, it is crucial to realize

Evaporation kinetics of surfactant solution droplets on rice (Oryza sativa) leaves

Science.gov (United States)

Cao, Li-Dong; Zheng, Li; Xu, Jun; Li, Feng-Min; Huang, Qi-Liang

2017-01-01

The dynamics of evaporating sessile droplets on hydrophilic or hydrophobic surfaces is widely studied, and many models for these processes have been developed based on experimental evidence. However, few research has been explored on the evaporation of sessile droplets of surfactant or pesticide solutions on target crop leaves. Thus, in this paper the impact of surfactant concentrations on contact angle, contact diameter, droplet height, and evolution of the droplets’ evaporative volume on rice leaf surfaces have been investigated. The results indicate that the evaporation kinetics of surfactant droplets on rice leaves were influenced by both the surfactant concentrations and the hydrophobicity of rice leaf surfaces. When the surfactant concentration is lower than the surfactant CMC (critical micelle concentration), the droplet evaporation time is much longer than that of the high surfactant concentration. This is due to the longer existence time of a narrow wedge region under the lower surfactant concentration, and such narrow wedge region further restricts the droplet evaporation. Besides, our experimental data are shown to roughly collapse onto theoretical curves based on the model presented by Popov. This study could supply theoretical data on the evaporation of the adjuvant or pesticide droplets for practical applications in agriculture. PMID:28472108

Partitioning of hydrophobic pesticides within a soil-water-anionic surfactant system.

Science.gov (United States)

Wang, Peng; Keller, Arturo A

2009-02-01

Surfactants can be added to pesticide-contaminated soils to enhance the treatment efficiency of soil washing. Our results showed that pesticide (atrazine and diuron) partitioning and desorbability within a soil-water-anionic surfactant system is soil particle-size dependent and is significantly influenced by the presence of anionic surfactant. Anionic surfactant (linear alkylbenzene sulphonate, LAS) sorption was influenced by its complexation with both the soluble and exchangeable divalent cations in soils (e.g. Ca2+, Mg2+). In this study, we propose a new concept: soil system hardness which defines the total amount of soluble and exchangeable divalent cations associated with a soil. Our results showed that anionic surfactant works better with soils having lower soil system hardness. It was also found that the hydrophobic organic compounds (HOCs) sorbed onto the LAS-divalent cation precipitate, resulting in a significant decrease in the aqueous concentration of HOC. Our results showed that the effect of exchangeable cations and sorption of HOC onto the surfactant precipitates needs to be considered to accurately predict HOC behavior within soil-water-anionic surfactant systems.

Physicochemical treatments of anionic surfactants wastewater: Effect on aerobic biodegradability.

Science.gov (United States)

Aloui, Fathi; Kchaou, Sonia; Sayadi, Sami

2009-05-15

The effect of different physicochemical treatments on the aerobic biodegradability of an industrial wastewater resulting from a cosmetic industry has been investigated. This industrial wastewater contains 11423 and 3148mgL(-1) of chemical oxygen demand (COD) and anionic surfactants, respectively. The concentration of COD and anionic surfactants were followed throughout the diverse physicochemical treatments and biodegradation experiments. Different pretreatments of this industrial wastewater using chemical flocculation process with lime and aluminium sulphate (alum), and also advanced oxidation process (electro-coagulation (Fe and Al) and electro-Fenton) led to important COD and anionic surfactants removals. The best results were obtained using electro-Fenton process, exceeding 98 and 80% of anionic surfactants and COD removals, respectively. The biological treatment by an isolated strain Citrobacter braakii of the surfactant wastewater, as well as the pretreated wastewater by the various physicochemical processes used in this study showed that the best results were obtained with electro-Fenton pretreated wastewater. The characterization of the treated surfactant wastewater by the integrated process (electro-coagulation or electro-Fenton)-biological showed that it respects Tunisian discharge standards.

Determining the Surfactant Consistent with Concrete in order to Achieve the Maximum Possible Dispersion of Multi walled Carbon Nano tubes in Keeping the Plain Concrete Properties

International Nuclear Information System (INIS)

Adresi, M.; Hassani, A.; Javadian, S.; Tulliani, J. M.

2016-01-01

A new surfactant combination compatible with concrete formulation is proposed to avoid unwanted air bubbles created during mixing process in the absence of a defoamer and to achieve the uniform and the maximum possible dispersion of multi walled carbon nano tubes (MWCNTs) in water and subsequently in concrete. To achieve this goal, three steps have been defined: (1) concrete was made with different types and amount of surfactants containing a constant amount of MWCNTs (0.05 wt%) and the air bubbles were eliminated with a proper defoamer. (2) Finding a compatible surfactant with concrete compositions and eliminating unwanted air bubbles in the absence of a common defoamer are of fundamental importance to significantly increase concrete mechanical properties. In this step, the results showed that the poly carboxylate super plasticizer (SP-C) (as a compatible surfactant) dispersed MWCNTs worse than SDS/DTAB but unwanted air bubbles were removed, so the defoamer can be omitted in the mixing process. (3) To solve the problem, a new compatible surfactant composition was developed and different ratios of surfactants were tested and evaluated by means of performance criteria mentioned above. The results showed that the new surfactant composition (SDS and SP-C) can disperse MWCNTs around 24% more efficiently than the other surfactant compositions.

Separation and recycling of nanoparticles using cloud point extraction with non-ionic surfactant mixtures.

Science.gov (United States)

Nazar, Muhammad Faizan; Shah, Syed Sakhawat; Eastoe, Julian; Khan, Asad Muhammad; Shah, Afzal

2011-11-15

A viable cost-effective approach employing mixtures of non-ionic surfactants Triton X-114/Triton X-100 (TX-114/TX-100), and subsequent cloud point extraction (CPE), has been utilized to concentrate and recycle inorganic nanoparticles (NPs) in aqueous media. Gold Au- and palladium Pd-NPs have been pre-synthesized in aqueous phases and stabilized by sodium 2-mercaptoethanesulfonate (MES) ligands, then dispersed in aqueous non-ionic surfactant mixtures. Heating the NP-micellar systems induced cloud point phase separations, resulting in concentration of the NPs in lower phases after the transition. For the Au-NPs UV/vis absorption has been used to quantify the recovery and recycle efficiency after five repeated CPE cycles. Transmission electron microscopy (TEM) was used to investigate NP size, shape, and stability. The results showed that NPs are preserved after the recovery processes, but highlight a potential limitation, in that further particle growth can occur in the condensed phases. Copyright © 2011 Elsevier Inc. All rights reserved.

Adsorption and intercalation of anionic surfactants onto layered ...

Indian Academy of Sciences (India)

Layered double hydroxides (LDH) with brucite like structure was modified with various anionic surfactants containing sulfonate, carboxyl, phosphonate and sulfate end group through ion-exchange method. XRD reports indicated that the sulfonate group containing surfactants led to an adsorption process whereas the sulfate ...

Fullerene surfactants and their use in polymer solar cells

Science.gov (United States)

Jen, Kwan-Yue; Yip, Hin-Lap; Li, Chang-Zhi

2015-12-15

Fullerene surfactant compounds useful as interfacial layer in polymer solar cells to enhance solar cell efficiency. Polymer solar cell including a fullerene surfactant-containing interfacial layer intermediate cathode and active layer.

Surfactant Ligand Removal and Rational Fabrication of Inorganically Connected Quantum Dots

KAUST Repository

Zhang, Haitao; Hu, Bo; Sun, Liangfeng; Hovden, Robert; Wise, Frank W.; Muller, David A.; Robinson, Richard D.

2011-01-01

in that no new surfactant ligands are introduced and the post-treated NC surfaces are nearly bare. The detailed mechanism study shows that the high reactivity between (NH 4) 2S and metal-surfactant ligand complexes enables the complete removal of surfactant

Mutagenicity of diesel exhaust soot dispersed in phospholipid surfactants

Energy Technology Data Exchange (ETDEWEB)

Wallace, W.; Keane, M.; Xing, S.; Harrison, J.; Gautam, M.; Ong, T.

1994-06-01

Organics extractable from respirable diesel exhaust soot particles by organic solvents have been known for some time to be direct acting frameshift mutagens in the Ames Salmonella typhimurium histidine reversion assay. Upon deposition in a pulmonary alveolus or respiratory bronchiole, respirable diesel soot particles will contact first the hypophase which is coated by and laden with surfactants. To model interactions of soot and pulmonary surfactant, the authors dispersed soots in vitro in the primary phospholipid pulmonary surfactant dipalmitoyl glycerophosphorylcholine (lecithin) (DPL) in physiological saline. They have shown that diesel soots dispersed in lecithin surfactant can express mutagenic activity, in the Ames assay system using S. typhimurium TA98, comparable to that expressed by equal amounts of soot extracted by dichloromethane/dimethylsulfoxide (DCM/DMSO). Here the authors report additional data on the same system using additional exhaust soots and also using two other phospholipids, dipalmitoyl glycerophosphoryl ethanolamine (DPPE), and dipalmitoyl phosphatidic acid (DPPA), with different ionic character hydrophilic moieties. A preliminary study of the surfactant dispersed soot in an eucaryotic cell test system also is reported.

Surface rheology of surfactant solutions close to equilibrium

NARCIS (Netherlands)

Baets, P.J.M.; Stein, H.N.

1994-01-01

In this paper the authors present surface rheol. measurements of various surfactant solns. close to equil. in a Langmuir trough. The authors find that the storage modulus is, in the systems investigated, higher than the loss modulus. The rheol. behavior depends strongly on the surfactant concn.,

Hydrogen Surfactant Effect on ZnO/GaN Heterostructures Growth

Science.gov (United States)

Zhang, Jingzhao; Zhang, Yiou; Tse, Kinfai; Zhu, Junyi

To grow high quality heterostructures based on ZnO and GaN, growth conditions that favor the layer by layer (Frank-Van der Merwe) growth mode have to be applied. However, if A wets B, B would not wet A without special treatments. A famous example is the epitaxial growth of Si/Ge/Si heterostructure with the help of arsenic surfactant in the late 1980s. It has been confirmed by the previous experiments and our calculations that poor crystal quality and 3D growth mode were obtained when GaN grown on ZnO polar surfaces while high quality ZnO was achieved on (0001) and (000-1)-oriented GaN. During the standard OMVPE growth processes, hydrogen is a common impurity and hydrogen-involved surface reconstructions have been well investigated experimentally and theoretically elsewhere. Due to the above facts, we proposed key growth strategies by using hydrogen as a surfactant to achieve ideal growth mode for GaN on ZnO (000-1) surface. This novel strategy may for the first time make the growth of high quality GaN single crystal on ZnO substrate possible. This surfactant effect is expected to largely improve the crystal quality and the efficiency of ZnO/GaN super lattices or other heterostructure devices. Part of the computing resources was provided by the High Performance Cluster Computing Centre, Hong Kong Baptist University. This work was supported by the start-up funding and direct Grant with the Project code of 4053134 and 3132748 at CUHK.

Tensiometry and dilational rheology of mixed β-lactoglobulin/ionic surfactant adsorption layers at water/air and water/hexane interfaces.

Science.gov (United States)

Dan, Abhijit; Gochev, Georgi; Miller, Reinhard

2015-07-01

Oscillating drop tensiometry was applied to study adsorbed interfacial layers at water/air and water/hexane interfaces formed from mixed solutions of β-lactoglobulin (BLG, 1 μM in 10 mM buffer, pH 7 - negative net charge) and the anionic surfactant SDS or the cationic DoTAB. The interfacial pressure Π and the dilational viscoelasticity modulus |E| of the mixed layers were measured for mixtures of varying surfactant concentrations. The double capillary technique was employed which enables exchange of the protein solution in the drop bulk by surfactant solution (sequential adsorption) or by pure buffer (washing out). The first protocol allows probing the influence of the surfactant on a pre-adsorbed protein layer thus studying the protein/surfactant interactions at the interface. The second protocol gives access to the residual values of Π and |E| measured after the washing out procedure thus bringing information about the process of protein desorption. The DoTAB/BLG complexes exhibit higher surface activity and higher resistance to desorption in comparison with those for the SDS/BLG complexes due to hydrophobization via electrostatic binding of surfactant molecules. The neutral DoTAB/BLG complexes achieve maximum elastic response of the mixed layer. Mixed BLG/surfactant layers at the water/oil interface are found to reach higher surface pressure and lower maximum dilational elasticity than those at the water/air surface. The sequential adsorption mode experiments and the desorption study reveal that binding of DoTAB to pre-adsorbed BLG globules is somehow restricted at the water/air surface in comparison with the case of complex formation in the solution bulk and subsequently adsorbed at the water/air surface. Maximum elasticity is achieved with washed out layers obtained after simultaneous adsorption, i.e. isolation of the most surface active DoTAB/BLG complex. These specific effects are much less pronounced at the W/H interface. Copyright © 2015 Elsevier Inc

Phase transitions in surfactant monolayers

International Nuclear Information System (INIS)

Casson, B.D.

1998-01-01

Two-dimensional phase transitions have been studied in surfactant monolayers at the air/water interface by sum-frequency spectroscopy and ellipsometry. In equilibrium monolayers of medium-chain alcohols C n H 2n+1 OH (n = 9-14) a transition from a two-dimensional crystalline phase to a liquid was observed at temperatures above the bulk melting point. The small population of gauche defects in the solid phase increased only slightly at the phase transition. A model of the hydrocarbon chains as freely rotating rigid rods allowed the area per molecule and chain tilt in the liquid phase to be determined. The area per molecule, chain tilt and density of the liquid phase all increased with increasing chain length, but for each chain length the density was higher than in a bulk liquid hydrocarbon. In a monolayer of decanol adsorbed at the air/water interface a transition from a two-dimensional liquid to a gas was observed. A clear discontinuity in the coefficient of ellipticity as a function of temperature showed that the transition is first-order. This result suggests that liquid-gas phase transitions in surfactant monolayers may be more widespread than once thought. A solid-liquid phase transition has also been studied in mixed monolayers of dodecanol with an anionic surfactant (sodium dodecyl sulphate) and with a homologous series of cationic surfactants (alkyltrimethylammonium bromides: C n TABs, n = 12, 14, 16). The composition and structure of the mixed monolayers was studied above and below the phase transition. At low temperatures the mixed monolayers were as densely packed as a monolayer of pure dodecanol in its solid phase. At a fixed temperature the monolayers under-went a first-order phase transition to form a phase that was less dense and more conformationally disordered. The proportion of ionic surfactant in the mixed monolayer was greatest in the high temperature phase. As the chain length of the C n TAB increased the number of conformational defects

Surfactant nebulisation prevents the adverse effects of surfactant therapy on blood pressure and cerebral blood flow in rabbits with severe respiratory failure

NARCIS (Netherlands)

Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto

1997-01-01

Objective: Surfactant replacement therapy for the neonatal respiratory distress syndrome has shown beneficial effects on lung function and survival. Recently, rapid fluctuations of haemodynamics and cerebral perfusion following surfactant instillation have beer, described and an association with the

(Cationic + nonionic) mixed surfactant aggregates for solubilisation of curcumin

International Nuclear Information System (INIS)

Kumar, Arun; Kaur, Gurpreet; Kansal, S.K.; Chaudhary, G.R.; Mehta, S.K.

2016-01-01

Highlights: • Critical micelle concentration of mixed surfactant has been measured. • Aqueous solubility and alkaline stability of curcumin has been significantly improved. • Location of curcumin within micelles has been evaluated. • Scavenging activity of curcumin has been improved. • Non-intercalative binding with ct-DNA has been observed. - Abstract: Curcumin is a potential drug for variety of diseases. Major limitations of curcumin are low water solubility, rapid hydrolytic degradation in alkaline medium and poor bioavailability. To overcome these limitations, highly potential mixed micellar system has been prepared. In order to reduce inter ionic repulsion and precipitation of surfactants, (cationic + non-ionic) mixed system have been chosen that directly influence its applicability. Hydrophobic chain of non-ionic surfactant significantly influences the cmc of mixed surfactant system as indicated by fluorescence and conductivity data. UV–visible spectroscopy analyses show that solubility, stability and antioxidant property of the curcumin is remarkably improved depending on cmc and aggregation number (N_a_g_g) of mixed surfactants, where N_a_g_g plays crucial role. Generally, curcumin undergoes complete degradation in slight basic medium, but stability has been maintained up to 8 h at pH-13 using formulated mixed micelles (only (20 to 25)% degraded). Location of curcumin which is monitored using emission spectroscopy, fluorescence quenching and "1H NMR spectroscopy techniques play the most important role. Observed results show that the major population of curcumin is located at the polar region and some are in hydrophobic region of the mixed micelles. To ensure the effect of mixed surfactants and curcumin loaded mixed surfactants on DNA, the interaction parameter indicates non-interclative interactions.

Dispersion of nanoparticulate suspensions using self-assembled surfactant aggregates

Science.gov (United States)

Singh, Pankaj Kumar

The dispersion of particles is critical for several industrial applications such as paints, inks, coatings, and cosmetics. Several emerging applications such as abrasives for precision polishing, and drug delivery systems are increasingly relying on nanoparticulates to achieve the desired performance. In the case of nanoparticles, the dispersion becomes more challenging because of the lack of fundamental understanding of dispersant adsorption and interparticle force prediction. Additionally, many of these processes use severe processing environments such as high normal forces (>100 mN/m), high shear forces (>10,000 s -1), and high ionic strengths (>0.1 M). Under such processing conditions, traditionally used dispersants based on electrostatics, and steric force repulsion mechanism may not be adequate. Hence, the development of optimally performing dispersants requires a fundamental understanding of the dispersion mechanism at the atomic/molecular scale. This study explores the use of self-assembled surfactant aggregates at the solid-liquid interface for dispersing nanoparticles in severe processing environments. Surfactant molecules can provide a feasible alternative to polymeric or inorganic dispersants for stabilizing ultrafine particles. The barrier to aggregation in the presence of surfactant molecules was measured using atomic force microscopy. The barrier heights correlated to suspension stability. To understand the mechanism for nanoparticulate suspension stability in the presence of surfactant films, the interface was characterized using zeta potential, contact angle, adsorption, and FT-IR (adsorbed surfactant film structure measurements). The effect of solution conditions such as pH and ionic strength on the suspension stability, and the self-assembled surfactant films was also investigated. It was determined that a transition from a random to an ordered orientation of the surfactant molecules at the interface was responsible for stability of

Impact of cationic surfactant on the self-assembly of sodium caseinate.

Science.gov (United States)

Vinceković, Marko; Curlin, Marija; Jurašin, Darija

2014-08-27

The impact of a cationic surfactant, dodecylammonium chloride (DDACl), on the self-assembly of sodium caseinate (SC) has been investigated by light scattering, zeta potential, and rheological measurements as well as by microscopy (transmission electron and confocal laser scanning microscopy). In SC dilute solutions concentration-dependent self-assembly proceeds through the formation of spherical associates and their aggregation into elongated structures composed of connected spheres. DDACl interacts with SC via its hydrophilic and hydrophobic groups, inducing changes in SC self-assembled structures. These changes strongly depend on the surfactant aggregation states (monomeric or micellar) as well as concentration ratio of both components, leading to the formation of soluble and insoluble complexes of nano- to microdimensions. DDACl monomers interact with SC self-assembled entities in a different way compared to their micelles. Surfactant monomers form soluble complexes (similar to surfactant mixed micelles) at lower SC concentration but insoluble gelatinous complexes at higher SC concentration. At surfactant micellar concentration soluble complexes with casein chains wrapped around surfactant micelles are formed. This study suggests that the use of proper cationic surfactant concentration will allow modification and control of structural changes of SC self-assembled entities.

Separation of oil and grease from oil sludge using surfactant

International Nuclear Information System (INIS)

Ainon Abdul Aziz; Syed Hakimi Sakuma Syed Ahmad; Zalina Laili

2005-01-01

The objective of the experiments was to observe the efficiency of the surfactant to remove oil and grease from oil sludges using various surfactant concentration ranging from 10 %, 15 %, 20 % and 30 %. The surfactant solution consists of two mixtures of Aqua 2000 and D Bond. The oil sludge were subjected to heating and surfactant treatment process. Remaining oil and grease concentration were observed on the oil sludges after treatment. Small scale experiments were conducted by heating process, without heating process and heating process with addition of sodium chloride. Surfactant solution was added in each process. Results shows that there is separation of oil and grease from the oil sludges. There were formation of mini emulsions (oil in water). The higher the concentration of surfactant used, the higher the concentrations of mini emulsion formed as observed. Solid remains after the treatment process were found to contain lesser oil concentration with presence of bitumen, sediment, organic and inorganic materials. After a washing process using distilled water, the solid was still black but less oily than before the treatment. There is no separation of oil occurred in aqueous solution for the control experiment. (Author)

New gluconamide-type cationic surfactants: Interactions with DNA and lipid membranes

Czech Academy of Sciences Publication Activity Database

Misiak, P.; Wilk, K. A.; Kral, Teresa; Wozniak, E.; Pruchnik, H.; Frackowiak, R.; Hof, Martin; Rózycka-Roszak, B.

180-181, OCT-NOV (2013), s. 44-54 ISSN 0301-4622 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388955 Keywords : Glucose-derived surfactant * Soft surfactant * Cationic surfactant Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.319, year: 2013

Use of surfactants in cleaning paraffin from oil wells

Energy Technology Data Exchange (ETDEWEB)

Liebold, G; Rehberg, W

1969-05-01

The use of surfactants is described especially oxethylated alkylphenols, in the cleaning of oil wells from paraffin. Aqueous 1 or 10% solutions of the surfactant were injected into the well through the annulus, partially in combination with demulsifiers (for example Separol-brands of BASF). Injection was accomplished continuously or in intervals; in the beginning of 50 ppm surfactant, afterward 15 to 30 ppm as related to the wet crude was necessary. Efficiency of the treatment could be proved by the decrease of pressure in the pipes, the loosening of paraffin shells, and considerably prolonged operation periods in wells which otherwise would have come to a standstill. In quite a number of wells, treatment with hot oil and electric heating could be completely replaced by injection of surfactants. (11 refs.)

Pulmonary Surfactants for Acute and Chronic Lung Diseases (Part II

Directory of Open Access Journals (Sweden)

O. A. Rozenberg

2014-01-01

Full Text Available Part 2 of the review considers the problem of surfactant therapy for acute respiratory distress syndrome (ARDS in adults and young and old children. It gives information on the results of surfactant therapy and prevention of ARDS in patients with severe concurrent trauma, inhalation injuries, complications due to complex expanded chest surgery, or severe pneumonias, including bilateral pneumonia in the presence of A/H1N1 influenza. There are data on the use of a surfactant in obstetric care and prevention of primary graft dysfunction during lung transplantation. The results of longterm use of surfactant therapy in Russia, suggesting that death rates from ARDS may be substantially reduced (to 20% are discussed. Examples of surfactant therapy for other noncritical lung diseases, such as permanent athelectasis, chronic obstructive pulmonary diseases, and asthma, as well tuberculosis, are also considered.

Structure-function relationships in pulmonary surfactant membranes: from biophysics to therapy.

Science.gov (United States)

Lopez-Rodriguez, Elena; Pérez-Gil, Jesús

2014-06-01

Pulmonary surfactant is an essential lipid-protein complex to maintain an operative respiratory surface at the mammalian lungs. It reduces surface tension at the alveolar air-liquid interface to stabilise the lungs against physical forces operating along the compression-expansion breathing cycles. At the same time, surfactant integrates elements establishing a primary barrier against the entry of pathogens. Lack or deficiencies of the surfactant system are associated with respiratory pathologies, which treatment often includes supplementation with exogenous materials. The present review summarises current models on the molecular mechanisms of surfactant function, with particular emphasis in its biophysical properties to stabilise the lungs and the molecular alterations connecting impaired surfactant with diseased organs. It also provides a perspective on the current surfactant-based strategies to treat respiratory pathologies. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy. Copyright © 2014 Elsevier B.V. All rights reserved.

Molecular dynamics simulations of surfactant and nanoparticle self-assembly at liquid-liquid interfaces

Energy Technology Data Exchange (ETDEWEB)

Luo Mingxiang; Dai, Lenore L [Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409 (United States)

2007-09-19

We have performed molecular dynamics (MD) simulations to investigate self-assembly at water-trichloroethylene (TCE) interfaces with the emphasis on systems containing modified hydrocarbon nanoparticles (1.2 nm in diameter) and sodium dodecyl sulfate (SDS) surfactants. The nanoparticles and surfactants were first distributed randomly in the water phase. The MD simulations have clearly shown the progress of migration and final equilibrium of the SDS molecules at the water-TCE interfaces with the nanoparticles either at or in the vicinity of the interfaces. One unique feature is the 'attachment' of surfactant molecules to the nanoparticle clusters in the water phase followed by the 'detachment' at the water-TCE interfaces. At low concentrations of surfactants, the surfactants and nanoparticles co-equilibrate at the interfaces. However, the surfactants, at high concentrations, competitively dominate the interfaces and deplete nanoparticles away from the interfaces. The interfacial properties, such as interfacial thickness and interfacial tension, are significantly influenced by the presence of the surfactants, but not the nanoparticles. The order of the surfactants at the interfaces increases with increasing surfactant concentration, but is independent of nanoparticle concentration. Finally, the simulation has shown that surfactants can aggregate along the water-TCE interfaces, with and without the presence of nanoparticles.

Preparation of nanocrystalline MgO by surfactant assisted precipitation method

International Nuclear Information System (INIS)

Rezaei, Mehran; Khajenoori, Majid; Nematollahi, Behzad

2011-01-01

Highlights: → Nanocrystalline magnesium oxide with high surface area. → MgO prepared with surfactant showed different morphologies compared with the sample prepared without surfactant. → MgO prepared with surfactant showed a plate-like shape. → Refluxing temperature and time and the surfactant to metal molar ratio affect the textural properties of MgO. -- Abstract: Nanocrystalline magnesium oxide with high surface area was prepared by a simple precipitation method using pluronic P123 triblock copolymer (Poly (ethylene glycol)-block, Poly (propylene glycol)-block, Poly (ethylene glycol)) as surfactant and under refluxing conditions. The prepared samples were characterized by X-ray diffraction (XRD), N 2 adsorption (BET) and scanning and transmission electron microscopies (SEM and TEM). The obtained results revealed that the refluxing time and temperature and the molar ratio of surfactant to metal affect the structural properties of MgO, because of the changes in the rate and extent of P123 adsorption on the prepared samples. The results showed that the addition of surfactant is effective to prepare magnesium oxide with high surface area and affects the morphology of the prepared samples. With increasing the P123/MgO molar ratio to 0.05 the pore size distribution was shifted to larger size. The sample prepared with addition of surfactant showed a plate-like shape which was completely different with the morphology of the sample prepared without surfactant. The formation of nanoplate-like MgO was related to higher surface density of Mg ions on the (0 0 1) plane than that on the other planes of the Mg(OH) 2 crystal. The (0 0 1) plane would be blocked preferentially by the adsorbed P123 molecules during the growing process of Mg(OH) 2 nanoentities and the growth on the (0 0 1) plane would be markedly restricted, and the consequence is the generation of nanoplate-like MgO. In addition, increase in refluxing temperature and time increased the specific surface area

Preparation of nanocrystalline MgO by surfactant assisted precipitation method

Energy Technology Data Exchange (ETDEWEB)

Rezaei, Mehran, E-mail: rezaei@kashanu.ac.ir [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Khajenoori, Majid; Nematollahi, Behzad [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of)

2011-10-15

Highlights: {yields} Nanocrystalline magnesium oxide with high surface area. {yields} MgO prepared with surfactant showed different morphologies compared with the sample prepared without surfactant. {yields} MgO prepared with surfactant showed a plate-like shape. {yields} Refluxing temperature and time and the surfactant to metal molar ratio affect the textural properties of MgO. -- Abstract: Nanocrystalline magnesium oxide with high surface area was prepared by a simple precipitation method using pluronic P123 triblock copolymer (Poly (ethylene glycol)-block, Poly (propylene glycol)-block, Poly (ethylene glycol)) as surfactant and under refluxing conditions. The prepared samples were characterized by X-ray diffraction (XRD), N{sub 2} adsorption (BET) and scanning and transmission electron microscopies (SEM and TEM). The obtained results revealed that the refluxing time and temperature and the molar ratio of surfactant to metal affect the structural properties of MgO, because of the changes in the rate and extent of P123 adsorption on the prepared samples. The results showed that the addition of surfactant is effective to prepare magnesium oxide with high surface area and affects the morphology of the prepared samples. With increasing the P123/MgO molar ratio to 0.05 the pore size distribution was shifted to larger size. The sample prepared with addition of surfactant showed a plate-like shape which was completely different with the morphology of the sample prepared without surfactant. The formation of nanoplate-like MgO was related to higher surface density of Mg ions on the (0 0 1) plane than that on the other planes of the Mg(OH){sub 2} crystal. The (0 0 1) plane would be blocked preferentially by the adsorbed P123 molecules during the growing process of Mg(OH){sub 2} nanoentities and the growth on the (0 0 1) plane would be markedly restricted, and the consequence is the generation of nanoplate-like MgO. In addition, increase in refluxing temperature and time

Tuning metal–carboxylate coordination in crystalline metal–organic frameworks through surfactant media

Energy Technology Data Exchange (ETDEWEB)

Gao, Junkuo [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Ye, Kaiqi [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012 (China); He, Mi [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Xiong, Wei-Wei; Cao, Wenfang; Lee, Zhi Yi [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Wang, Yue [State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012 (China); Wu, Tom [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Huo, Fengwei [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Liu, Xiaogang [Department of Chemistry, National University of Singapore, Singapore 117543 (Singapore); Institute of Materials Research Engineering, Agency for Science, Technology and Research, Singapore 117602 (Singapore); Zhang, Qichun, E-mail: qczhang@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

2013-10-15

Although it has been widely demonstrated that surfactants can efficiently control the size, shape and surface properties of micro/nanocrystals of metal–organic frameworks (MOFs) due to the strong interactions between surfactants and crystal facets of MOFs, the use of surfactants as reaction media to grow MOF single crystals is unprecedented. In addition, compared with ionic liquids, surfactants are much cheaper and can have multifunctional properties such as acidic, basic, neutral, cationic, anionic, or even block. These factors strongly motivate us to develop a new synthetic strategy: growing crystalline MOFs in surfactants. In this report, eight new two-dimensional (2D) or three-dimensional (3D) MOFs have been successfully synthesized in an industrially-abundant and environmentally-friendly surfactant: polyethylene glycol-200 (PEG-200). Eight different coordination modes of carboxylates, ranging from monodentate η{sup 1} mode to tetra-donor coordination µ{sub 3}-η{sup 1}:η{sup 2}:η{sup 1} mode, have been founded in our research. The magnetic properties of Co-based MOFs were investigated and MOF NTU-Z6b showed a phase transition with a Curie temperature (T{sub c}) at 5 K. Our strategy of growing crystalline MOFs in surfactant could offer exciting opportunities for preparing novel MOFs with diverse structures and interesting properties. - Graphical abstract: Surfactants have been used as reaction media to grow MOF single crystals for the first time. Eight new two-dimensional or three-dimensional MOFs were successfully synthesized in surfactant polyethylene glycol-200 (PEG-200). Coordination modes of carboxylates up to eight were founded. Our strategy of growing crystalline MOFs in surfactant could offer exciting opportunities for preparing novel MOFs with diverse structures and interesting properties. Display Omitted - Highlights: • Surfactant-thermal synthesis of crystalline metal–organic frameworks. • Eight new 2-D or 3-D metal–organic frameworks

A simplified treatment of surfactant effects on cloud drop activation

Directory of Open Access Journals (Sweden)

T. Raatikainen

2011-02-01

Full Text Available Dissolved surface active species, or surfactants, have a tendency to partition to solution surface and thereby decrease solution surface tension. Activating cloud droplets have large surface-to-volume ratios, and the amount of surfactant molecules in them is limited. Therefore, unlike with macroscopic solutions, partitioning to the surface can effectively deplete the droplet interior of surfactant molecules.

Surfactant partitioning equilibrium for activating cloud droplets has so far been solved numerically from a group of non-linear equations containing the Gibbs adsorption equation coupled with a surface tension model and an optional activity coefficient model. This can be a problem when surfactant effects are examined by using large-scale cloud models. Namely, computing time increases significantly due to the partitioning calculations done in the lowest levels of nested iterations.

Our purpose is to reduce the group of non-linear equations to simple polynomial equations with well known analytical solutions. In order to do that, we describe surface tension lowering using the Szyskowski equation, and ignore all droplet solution non-idealities. It is assumed that there is only one surfactant exhibiting bulk-surface partitioning, but the number of non-surfactant solutes is unlimited. It is shown that the simplifications cause only minor errors to predicted bulk solution concentrations and cloud droplet activation. In addition, computing time is decreased at least by an order of magnitude when using the analytical solutions.

Flow improvers for water injection based on surfactants

Energy Technology Data Exchange (ETDEWEB)

Oskarsson, H.; Uneback, I.; Hellsten, M.

2006-03-15

In many cases it is desirable to increase the flow of injection water when an oil well deteriorates. It is very costly in offshore operation to lay down an additional water pipe to the injection site. Flow improvers for the injection water will thus be the most cost-effective way to increase the flow rate. During the last years water-soluble polymers have also been applied for this purpose. These drag-reducing polymers are however only slowly biodegraded which has been an incentive for the development of readily biodegradable surfactants as flow improvers for injection water. A combination of a zwitterionic and an anionic surfactant has been tested in a 5.5 inch, 700 m long flow loop containing sulphate brine with salinity similar to sea water. A drag reduction between 75 and 80% was achieved with 119 ppm in solution of the surfactant blend at an average velocity of 1.9 m/s and between 50 and 55% at 2.9 m/s. The surfactants in this formulation were also found to be readily biodegradable in sea water and low bio accumulating which means they have an improved environmental profile compared to the polymers used today. Due to the self-healing properties of the drag-reducing structures formed by surfactants, these may be added before the pump section - contrary to polymers which are permanently destroyed by high shear forces. (Author)

Synthesis of mesoporous nano-hydroxyapatite by using zwitterions surfactant

Science.gov (United States)

Mesoporous nano-hydroxyapatite (mn-HAP) was successfully synthesized via a novel micelle-templating method using lauryl dimethylaminoacetic acid as zwitterionic surfactant. The systematic use of such a surfactant in combination with microwave energy inputenables the precise contr...

Effects of concentration, head group, and structure of surfactants on the degradation of phenanthrene

International Nuclear Information System (INIS)

Jin Danyue; Jiang Xia; Jing Xin; Ou Ziqing

2007-01-01

The effects of concentration, polar/ionic head group, and structure of surfactants on the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in the aqueous phase, as well as their effects on the bacterial activity were investigated. The toxicity ranking of studied surfactants is: non-ionic surfactants (Tween 80, Brij30, 10LE and Brij35) -1 ) served the sole carbon and energy resource. However, the degradation of 14 C-phenanthrene showed either a decrease or no obvious change with the surfactants present at all tested concentrations (5-40 mg L -1 ). Thus, the surfactant addition is not beneficial to the removal of phenanthrene or other PAH contaminants due presumably to the preferential utilization of surfactants at low levels as the non-toxic nutrient resource and to the high toxicity of the surfactants at high levels to the microorganism activity. Biodegradation of phenanthrene was also influenced by the surfactant concentration, head group type, and structure. Much more research has yet to be completed on the use of surfactants for soil remediation due to the surfactant toxicity or biodegradation effect

Systems of mechanized and reactive droplets powered by multi-responsive surfactants

Science.gov (United States)

Yang, Zhijie; Wei, Jingjing; Sobolev, Yaroslav I.; Grzybowski, Bartosz A.

2018-01-01

Although ‘active’ surfactants, which are responsive to individual external stimuli such as temperature, electric or magnetic fields, light, redox processes or chemical agents, are well known, it would be interesting to combine several of these properties within one surfactant species. Such multi-responsive surfactants could provide ways of manipulating individual droplets and possibly assembling them into larger systems of dynamic reactors. Here we describe surfactants based on functionalized nanoparticle dimers that combine all of these and several other characteristics. These surfactants and therefore the droplets that they cover are simultaneously addressable by magnetic, optical and electric fields. As a result, the surfactant-covered droplets can be assembled into various hierarchical structures, including dynamic ones, in which light powers the rapid rotation of the droplets. Such rotating droplets can transfer mechanical torques to their non-nearest neighbours, thus acting like systems of mechanical gears. Furthermore, droplets of different types can be merged by applying electric fields and, owing to interfacial jamming, can form complex, non-spherical, ‘patchy’ structures with different surface regions covered with different surfactants. In systems of droplets that carry different chemicals, combinations of multiple stimuli can be used to control the orientations of the droplets, inter-droplet transport, mixing of contents and, ultimately, sequences of chemical reactions. Overall, the multi-responsive active surfactants that we describe provide an unprecedented level of flexibility with which liquid droplets can be manipulated, assembled and reacted.

Numerical approach for enhanced oil recovery with surfactant flooding

Directory of Open Access Journals (Sweden)

Sadegh Keshtkar

2016-03-01

Full Text Available The remained oil in the reservoir after conventional water-flooding processes, forms a dispersed phase in the form of oil drops which is trapped by capillary forces and is almost about 70% of the original oil in the place (OOIP. To reduce oil residual saturation in laboratory experiments and field projects, surfactant flooding is effective via decreasing the interfacial tension mobility ratio between oil and water phases. Estimation of the role of design variables, like chemical concentrations, partition coefficient and injection rate in different performance quantities, considering a heterogeneous and multiphase oil reservoir is a critical stage for optimal design. Increasing demand for oil production from water-flooded reservoirs has caused an increasing interest in surfactant-polymer (SP and alkali-surfactant-polymer (ASP. Modeling minimizes the risk of high cost of chemicals by improving our insight of process. In the present paper, a surfactant compositional flood model for a three-component (water, petroleum and surfactant, two phase (aqueous and oleic system is studied. A homogeneous, two-dimensional, isothermal reservoir with no free gas or alkali is assumed. The governing equations are in three categories: the continuity equations for the transport of each component, Darcy's equation for the transport of each phase and other auxiliary equations. The equations are solved by finite-differences using a procedure implicit in pressure and explicit in saturation. The validation of the model is achieved through comparing the modeling results with CMG simulators and Buckley–Leverett theory. The results of modeling showed good agreement with CMG results, and the comparison with Buckley–Leverett theory is explained according to different assumptions. After validation of the model, in order to investigate sensitivity analysis, the effects of system variables (partition coefficient, surface tension, oil viscosity and surface injection

Performance improvement of ionic surfactant flooding in carbonate rock samples by use of nanoparticles

Directory of Open Access Journals (Sweden)

Mohammad Ali Ahmadi

2016-07-01

Full Text Available Abstract Various surfactants have been used in upstream petroleum processes like chemical flooding. Ultimately, the performance of these surfactants depends on their ability to reduce the interfacial tension between oil and water. The surfactant concentration in the aqueous solution decreases owing to the loss of the surfactant on the rock surface in the injection process. The main objective of this paper is to inhibit the surfactant loss by means of adding nanoparticles. Sodium dodecyl sulfate and silica nanoparticles were used as ionic surfactant and nanoparticles in our experiments, respectively. AEROSIL® 816 and AEROSIL® 200 are hydrophobic and hydrophilic nanoparticles. To determine the adsorption loss of the surfactant onto rock samples, a conductivity approach was used. Real carbonate rock samples were used as the solid phase in adsorption experiments. It should be noted that the rock samples were water wet. This paper describes how equilibrium adsorption was investigated by examining adsorption behavior in a system of carbonate sample (solid phase and surfactant solution (aqueous phase. The initial surfactant and nanoparticle concentrations were 500–5000 and 500–2000 ppm, respectively. The rate of surfactant losses was extremely dependent on the concentration of the surfactant in the system, and the adsorption of the surfactant decreased with an increase in the nanoparticle concentration. Also, the hydrophilic nanoparticles are more effective than the hydrophobic nanoparticles.

Determination of the Critical Micelle Concentration of Neutral and Ionic Surfactants with Fluorometry, Conductometry, and Surface Tension-A Method Comparison.

Science.gov (United States)

Scholz, Norman; Behnke, Thomas; Resch-Genger, Ute

2018-01-01

Micelles are of increasing importance as versatile carriers for hydrophobic substances and nanoprobes for a wide range of pharmaceutical, diagnostic, medical, and therapeutic applications. A key parameter indicating the formation and stability of micelles is the critical micelle concentration (CMC). In this respect, we determined the CMC of common anionic, cationic, and non-ionic surfactants fluorometrically using different fluorescent probes and fluorescence parameters for signal detection and compared the results with conductometric and surface tension measurements. Based upon these results, requirements, advantages, and pitfalls of each method are discussed. Our study underlines the versatility of fluorometric methods that do not impose specific requirements on surfactants and are especially suited for the quantification of very low CMC values. Conductivity and surface tension measurements yield smaller uncertainties particularly for high CMC values, yet are more time- and substance consuming and not suitable for every surfactant.

The interactions between ionic surfactants and phosphatidylcholine vesicles: Conductometry

Science.gov (United States)

Tsao, Heng-Kwong; Tseng, Wen Liang

2001-11-01

The interaction between ionic surfactants and phosphatidylcholine vesicles, which are prepared without addition of buffer and salt, is investigated by conductivity measurements. On the basis of the vesicle acting as a trap of charge carriers, the bilayer/aqueous phase partition coefficient K and the surfactant/lipid molar ratio Re of nine surfactants are determined. The thermodynamic consistency is satisfied by the measured parameters. The effects of the alkyl chain length (C10-C16) and ionic head group are then studied. The inverse partition coefficient K-1 is linearly related to the critical micelle concentration. The solubilizing ability Reb is a consequence of the competition between the surfactant incorporation into the bilayer and the formation of micelles. Consequently, the K parameter rises whereas the Reb parameter declines as the chain length is increased. The influence due to addition of salt is also discussed.

Practical Considerations and Challenges Involved in Surfactant Enhanced Bioremediation of Oil

Directory of Open Access Journals (Sweden)

Sagarika Mohanty

2013-01-01

Full Text Available Surfactant enhanced bioremediation (SEB of oil is an approach adopted to overcome the bioavailability constraints encountered in biotransformation of nonaqueous phase liquid (NAPL pollutants. Fuel oils contain n-alkanes and other aliphatic hydrocarbons, monoaromatics, and polynuclear aromatic hydrocarbons (PAHs. Although hydrocarbon degrading cultures are abundant in nature, complete biodegradation of oil is rarely achieved even under favorable environmental conditions due to the structural complexity of oil and culture specificities. Moreover, the interaction among cultures in a consortium, substrate interaction effects during the degradation and ability of specific cultures to alter the bioavailability of oil invariably affect the process. Although SEB has the potential to increase the degradation rate of oil and its constituents, there are numerous challenges in the successful application of this technology. Success is dependent on the choice of appropriate surfactant type and dose since the surfactant-hydrocarbon-microorganism interaction may be unique to each scenario. Surfactants not only enhance the uptake of constituents through micellar solubilization and emulsification but can also alter microbial cell surface characteristics. Moreover, hydrocarbons partitioned in micelles may not be readily bioavailable depending on the microorganism-surfactant interactions. Surfactant toxicity and inherent biodegradability of surfactants may pose additional challenges as discussed in this review.

Practical Considerations and Challenges Involved in Surfactant Enhanced Bioremediation of Oil

Science.gov (United States)

Mohanty, Sagarika; Jasmine, Jublee

2013-01-01

Surfactant enhanced bioremediation (SEB) of oil is an approach adopted to overcome the bioavailability constraints encountered in biotransformation of nonaqueous phase liquid (NAPL) pollutants. Fuel oils contain n-alkanes and other aliphatic hydrocarbons, monoaromatics, and polynuclear aromatic hydrocarbons (PAHs). Although hydrocarbon degrading cultures are abundant in nature, complete biodegradation of oil is rarely achieved even under favorable environmental conditions due to the structural complexity of oil and culture specificities. Moreover, the interaction among cultures in a consortium, substrate interaction effects during the degradation and ability of specific cultures to alter the bioavailability of oil invariably affect the process. Although SEB has the potential to increase the degradation rate of oil and its constituents, there are numerous challenges in the successful application of this technology. Success is dependent on the choice of appropriate surfactant type and dose since the surfactant-hydrocarbon-microorganism interaction may be unique to each scenario. Surfactants not only enhance the uptake of constituents through micellar solubilization and emulsification but can also alter microbial cell surface characteristics. Moreover, hydrocarbons partitioned in micelles may not be readily bioavailable depending on the microorganism-surfactant interactions. Surfactant toxicity and inherent biodegradability of surfactants may pose additional challenges as discussed in this review. PMID:24350261

Nanocomposites of PP and bentonite clay modified with different surfactants

International Nuclear Information System (INIS)

Rodrigues, Andre W.B.; Agrawal, Pankaj; Araujo, Edcleide M.; Melo, Tomas J.A.; Ueki, Marcelo M.

2009-01-01

The aim of this work was the development of nano composites of polypropylene (PP) and national bentonite clay modified with different surfactants. The results of X-Ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) showed that the organophilization process was effective. The surfactants led to a significant increase in the basal spacing of Brasgel PA clay. XRD results of the mixture PP/Brasgel PA clay modified with Praepagem WB surfactant indicated that a nanocomposite with intercalated structure was formed. When the Brasgel PA clay was modified with Praepagem HY surfactant, DRX results indicated that a micro composite was formed. Screw speed, clay content and PP viscosity had no influence on the XRD pattern of the obtained materials. (author)

Factors controlling leaching of polycyclic aromatic hydrocarbons from petroleum source rock using nonionic surfactant

Energy Technology Data Exchange (ETDEWEB)

Akinlua, Akinsehinwa [Obafemi Awolowo Univ., Ile-Ife (Nigeria). Fossil Fuels and Environmental Geochemistry Group; Jochmann, Maik A.; Qian, Yuan; Schmidt, Torsten C. [Duisburg-Essen Univ., Essen (Germany). Instrumental Analytical Chemistry; Sulkowski, Martin [Duisburg-Essen Univ., Essen (Germany). Inst. of Environmental Analytical Chemistry

2012-03-15

The extraction of polycyclic aromatic hydrocarbons (PAHs) from petroleum source rock by nonionic surfactants with the assistance of microwave irradiation was investigated and the conditions for maximum yield were determined. The results showed that the extraction temperatures and type of surfactant have significant effects on extraction yields of PAHs. Factors such as surfactant concentration, irradiation power, sample/solvent ratio and mixing surfactants (i.e., mixture of surfactant at specific ratio) also influence the extraction efficiencies for these compounds. The optimum temperature for microwave-assisted nonionic surfactant extraction of PAHs from petroleum source rock was 120 C and the best suited surfactant was Brij 35. The new method showed extraction efficiencies comparable to those afforded by the Soxhlet extraction method, but a reduction of the extraction times and environmentally friendliness of the new nonionic surfactant extraction system are clear advantages. The results also show that microwave-assisted nonionic surfactant extraction is a good and efficient green analytical preparatory technique for geochemical evaluation of petroleum source rock. (orig.)

Molecular dynamics simulations of phase separation in the presence of surfactants

DEFF Research Database (Denmark)

Laradji, Mohamed; Mouritsen, Ole G.; Toxvaerd, Søren

1994-01-01

The dynamics of phase separation in two-dimensional binary mixtures diluted by surfactants is studied by means of molecular dynamics simulations. In contrast to pure binary systems, characterized by an algebraic time dependence of the average domain size, we find that systems containing surfactants...... not fully phase separate, we observe a dynamical scaling which is independent of the surfactant concentration. The results of these simulations are in general in agreement with previous Langevin simulations [Laradji, Guo, Grant, and Zuckermann, J. Phys. A 44, L629 (1991)] and a theory of Ostwald ripening...... exhibit nonalgebraic, slow dynamics. The average domain size eventually saturates at a value inversely proportional to the surfactant concentration. We also find that phase separation in systems with different surfactant concentrations follow a crossover scaling form. Finally, although these systems do...

Marine toxicity and persistence of surfactants used in the petroleum producing industry

International Nuclear Information System (INIS)

Maddin, C.M.

1991-01-01

This paper presents a survey of marine toxicity and biodegradability data for surfactants used in the petroleum industry. Surfactants are key chemicals in the formulation of products such as emulsifiers, demulsifiers, dispersants and inhibitors. They are also used directly as foaming and defoaming agents. Because they function at low concentrations, below 1%, and have a tendency to adsorb on solid surfaces, their long-term environmental effects are minimal. In applications such as cementing, surfactants cannot migrate into the environment and, thus, have no bioavailability. The possibility of environmental contamination has caused well operators and regulatory agencies to require fish toxicity and persistence data for products used in servicing wells. This data has been organized for nonionic, anionic, cationic and amphoteric surfactants. Nonionic surfactants are toxic to fish at concentrations below 10 mg/L to over 2500 mg/L depending on their chemical compositions. Anionic surfactants are toxic to fish at concentrations under 1 mg/L to several hundred mg/L depending on their chemical compositions. cationic and amphoteric surfactants are generally toxic to fish at concentrations below 50 mg/L. Overall efforts are aimed at low toxicity and high biodegradability with the least compromise in product efficiency. This requires the continual testing and environmental evaluation of surfactants summarized herein

Numerical Study of Surfactant Dynamics during Emulsification in a T-Junction Microchannel.

Science.gov (United States)

Riaud, Antoine; Zhang, Hao; Wang, Xueying; Wang, Kai; Luo, Guangsheng

2018-04-18

Microchannel emulsification requires large amounts of surfactant to prevent coalescence and improve emulsions lifetime. However, most numerical studies have considered surfactant-free mixtures as models for droplet formation in microchannels, without taking into account the distribution of surfactant on the droplet surface. In this paper, we investigate the effects of nonuniform surfactant coverage on the microfluidic flow pattern using an extended lattice-Boltzmann model. This numerical study, supported by micro-particle image velocimetry experiments, reveals the likelihood of uneven distribution of surfactant during the droplet formation and the appearance of a stagnant cap. The Marangoni effect affects the droplet breakup by increasing the shear rate. According to our results, surfactant-free and surfactant-rich droplet formation processes are qualitatively different, such that both the capillary number and the Damköhler number should be considered when modeling the droplet generation in microfluidic devices. The limitations of traditional volume and pressure estimation methods for determining the dynamic interfacial tension are also discussed on the basis of the simulation results.

Extraction and Characterization of Surfactants from Atmospheric Aerosols.

Science.gov (United States)

Nozière, Barbara; Gérard, Violaine; Baduel, Christine; Ferronato, Corinne

2017-04-21

Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in the Earth's atmosphere, a central process in meteorology, hydrology, and for the climate system. But because specific extraction and characterization of these compounds have been lacking for decades, very little is known on their identity, properties, mode of action and origins, thus preventing the full understanding of cloud formation and its potential links with the Earth's ecosystems. In this paper we present recently developed methods for 1) the targeted extraction of all the surfactants from atmospheric aerosol samples and for the determination of 2) their absolute concentrations in the aerosol phase and 3) their static surface tension curves in water, including their Critical Micelle Concentration (CMC). These methods have been validated with 9 references surfactants, including anionic, cationic and non-ionic ones. Examples of results are presented for surfactants found in fine aerosol particles (diameter <1 μm) collected at a coastal site in Croatia and suggestions for future improvements and other characterizations than those presented are discussed.

Use of functionalized surfactants in flame atomic analysis: Final technical report

International Nuclear Information System (INIS)

Armstrong, D.W.

1987-01-01

Research results in the following areas are briefly summarized: basic properties of surfactants, micelles, and cyclodextrins as they relate to chemical analysis; use of functionalized surfactants, micelles, and cyclodextrins in spectroscopic analysis; macromolecular separation theory and mechanism; use of functionalized surfactants and cyclodextrins in separations; capillary work for future coupling of spectroscopic and LC projects

Poloxamer-Decorated Polymer Nanoparticles for Lung Surfactant Compatibility

DEFF Research Database (Denmark)

Beck-Broichsitter, Moritz; Bohr, Adam; Ruge, Christian A

2017-01-01

Lung-delivered polymer nanoparticles provoked dysfunction of the essential lung surfactant system. A steric shielding of the nanoparticle surface with poloxamers could minimize the unwanted interference of polymer nanoparticles with the biophysical function of lung surfactant. The extent of poly......(styrene) and poly(lactide) nanoparticle-induced lung surfactant inhibition could be related to the type and content of the applied poloxamer. Escalations of the adsorbed coating layer thickness (>3 nm) as well as concentration (brush- rather than mushroom-like conformation of poly(ethylene glycol), chain......-associated proteins. Poloxamer-modified polymer nanoparticles represent a promising nanomedicine platform intended for respiratory delivery revealing negligible effects on the biophysical functionality of the lining layer present in the deep lungs....

Fragment-based approach to calculate hydrophobicity of anionic and nonionic surfactants derived from chromatographic retention on a C18 stationary phase.

Science.gov (United States)

Hammer, Jort; Haftka, Joris J-H; Scherpenisse, Peter; Hermens, Joop L M; de Voogt, Pim W P

2017-02-01

To predict the fate and potential effects of organic contaminants, information about their hydrophobicity is required. However, common parameters to describe the hydrophobicity of organic compounds (e.g., octanol-water partition constant [K OW ]) proved to be inadequate for ionic and nonionic surfactants because of their surface-active properties. As an alternative approach to determine their hydrophobicity, the aim of the present study was therefore to measure the retention of a wide range of surfactants on a C 18 stationary phase. Capacity factors in pure water (k' 0 ) increased linearly with increasing number of carbon atoms in the surfactant structure. Fragment contribution values were determined for each structural unit with multilinear regression, and the results were consistent with the expected influence of these fragments on the hydrophobicity of surfactants. Capacity factors of reference compounds and log K OW values from the literature were used to estimate log K OW values for surfactants (log KOWHPLC). These log KOWHPLC values were also compared to log K OW values calculated with 4 computational programs: KOWWIN, Marvin calculator, SPARC, and COSMOThermX. In conclusion, capacity factors from a C 18 stationary phase are found to better reflect hydrophobicity of surfactants than their K OW values. Environ Toxicol Chem 2017;36:329-336. © 2016 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC. © 2016 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.

Surfactant therapy for maternal blood aspiration: an unusual cause of neonatal respiratory distress syndrome.

Science.gov (United States)

Celik, Istemi Han; Demirel, Gamze; Canpolat, Fuat Emre; Erdeve, Omer; Dilmen, Ugur

2012-10-01

Surfactant replacement therapy is the main treatment of neonatal respiratory distress syndrome. However, surfactant therapy has been shown to be effective in the treatment of other diseases causing neonatal respiratory diseases such as pulmonary hemorrhage, meconium aspiration syndrome, pneumonia/sepsis, pulmonary edema or acute lung injury resulting a secondary surfactant deficiency (SSD). Rarely, as like as in the present patient, exogenous blood aspiration such as breast milk or formula aspiration may lead to SSD. Blood in alveolus leads to a significant biochemical and functional disturbance of the surfactant system and inhibits surfactant production. Here, the authors report a preterm infant of 33 wk gestational age with secondary surfactant deficiency due to maternal blood aspiration because of abruptio placentae. She was received two courses of beractant, a natural bovine surfactant, therapy in 24 h. She was extubated on second day and did not require oxygen on 4(th) day. To the authors' knowledge, this is the first reported case of SSD due to maternal blood aspiration treated with surfactant. In conditions such as abruptio placentae, infant should be protected from blood aspiration and if respiratory distress occurs, surfactant inhibition and need for surfactant administration should be considered.

The Accelerated Late Adsorption of Pulmonary Surfactant

OpenAIRE

Loney, Ryan W.; Anyan, Walter R.; Biswas, Samares C.; Rananavare, Shankar B.; Hall, Stephen B.

2011-01-01

Adsorption of pulmonary surfactant to an air−water interface lowers surface tension (γ) at rates that initially decrease progressively, but which then accelerate close to the equilibrium γ. The studies here tested a series of hypotheses concerning mechanisms that might cause the late accelerated drop in γ. Experiments used captive bubbles and a Wilhelmy plate to measure γ during adsorption of vesicles containing constituents from extracted calf surfactant. The faster fall in γ reflects faster...

Characterization of a Biomimetic Mesophase Composed of Nonionic Surfactants and an Aqueous Solvent.

Science.gov (United States)

Adrien, V; Rayan, G; Reffay, M; Porcar, L; Maldonado, A; Ducruix, A; Urbach, W; Taulier, N

2016-10-11

We have investigated the physical and biomimetic properties of a sponge (L 3 ) phase composed of pentaethylene glycol monododecyl ether (C 12 E 5 ), a nonionic surfactant, an aqueous solvent, and a cosurfactant. The following cosurfactants, commonly used for solubilizing membrane proteins, were incorporated: n-octyl-β-d-glucopyranoside (β-OG), n-dodecyl-β-d-maltopyranoside (DDM), 4-cyclohexyl-1-butyl-β-d-maltoside (CYMAL-4), and 5-cyclohexyl-1-pentyl-β-d-maltoside (CYMAL-5). Partial phase diagrams of these systems were created. The L 3 phase was characterized using crossed polarizers, diffusion of a fluorescent probe by fluorescence recovery after pattern photobleaching (FRAPP), and freeze fracture electron microscopy (FFEM). By varying the hydration of the phase, we were able to tune the distance between adjacent bilayers. The characteristic distance (d b ) of the phase was obtained from small angle scattering (SAXS/SANS) as well as from FFEM, which yielded complementary d b values. These d b values were neither affected by the nature of the cosurfactant nor by the addition of membrane proteins. These findings illustrate that a biomimetic surfactant sponge phase can be created in the presence of several common membrane protein-solubilizing detergents, thus making it a versatile medium for membrane protein studies.

Binding of alkylpyridinium chloride surfactants to sodium polystyrene sulfonate

NARCIS (Netherlands)

Ishiguro, M.; Koopal, L.K.

2009-01-01

Binding of cationic surfactants to anionic polymers is well studied. However, the surfactant binding characteristics at very low concentration near the start of binding and at high concentration, where charge compensation may Occur. are less well known. Therefore, the binding characteristics of

Optimization of surfactant application for synthetic drilling fluid; Otimizacao da aplicacao de emulsificante em fluidos de perfuracao sinteticos

Energy Technology Data Exchange (ETDEWEB)

Arruda, Jefferson Teixeira [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Santos, Telma Pitanga; Medeiros, Ana Catarina da Rocha; Garcia, Rosangela Balaban [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Lab. de Pesquisa em Petroleo

2008-07-01

The most common synthetic drilling fluids are made of polymerized olefins, paraffin and esters, which have absence of aromatics hydrocarbons and biodegradability as advantages. These fluids have good performance during the drilling operations (high thermal stability) and have low toxicity. Nevertheless, their big disadvantage is the high cost, which limits their use. One of the biggest challenges in working with synthetic fluids is the control of water/oil emulsion stability, being the surfactant the main agent responsible for keeping this stability between both phases of the fluid. The water/oil and oil/water emulsion is defined by the chemical nature of the surfactant. The emulsions can be changed from oil/water to water/oil and vice versa by many mechanisms, such as temperature variation, addition of another surfactant and alteration of the disperse phase volumetric percentage. The aim of this work was the optimization of synthetic drilling fluids formulations by using commercial surfactants. The optimized formulations showed similar rheological properties. After aging at high temperature (300 deg F), some tendency to migration of oil phase in both fluids was observed. This result was associated to the fluid's viscosity. However, the formulations showed high electrical stability, indicating formation of stable emulsions. The HTHP filtration volumes were small. (author)

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

Energy Technology Data Exchange (ETDEWEB)

P. Somasundaran

2008-09-20

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

Production technology readiness assessment of surfactant in the research center for Chemistry-Indonesian Institute of Sciences

Science.gov (United States)

Setiawan, Arief Ameir Rahman; Sulaswatty, Anny

2017-11-01

The common problem faced by the institution working on research, innovation and technology development is lack of quantitative measures to determine the technology readiness of research. No common communication language between R & D Institutions and industry about the level of preparedness of a research resulting a barrier to technology diffusion interaction. This lack of connection between R & D institutes with industry may lead to "sluggishness" occurs in innovating. For such circumstance, assessing technology readiness of research is very important. One of wide spread methods for the assessment is Technology Readiness Level (TRL, also known as Technometer), which is introduced by NASA (National Aeronautics and Space Administration). TRL is a general guide that provides an overview of maturity level of a technology. This study aims to identify and demonstrate the implementation of TRL to assess a number of surfactant researches in the Research Center for Chemistry, Indonesian Institute of Sciences. According to the assessment, it has been obtained the surfactant recommended for further development towards commercialization of R & D results, i.e. Glycerol Mono Stearate (GMS), which has reached the level of TRL 7.

Distribution of endotracheally instilled surfactant protein SP-C in lung-lavaged rabbits.

NARCIS (Netherlands)

Bambang Oetomo, Sidarto; de Leij, Louis; Curstedt, T; ter Haar, J G; Schoots, Coenraad; Wildevuur, Charles; Okken, Albert

In lung-lavaged surfactant-deficient rabbits (n = 6) requiring artificial ventilation, porcine surfactant was instilled endotracheally. This resulted in improvement of lung function so that the animals could be weaned off artificial ventilation. The animals were killed 4 1/2 h after surfactant

The effect of titanium dioxide nanoparticles on pulmonary surfactant function and ultrastructure

Directory of Open Access Journals (Sweden)

Braun Armin

2009-09-01

Full Text Available Abstract Background Pulmonary surfactant reduces surface tension and is present at the air-liquid interface in the alveoli where inhaled nanoparticles preferentially deposit. We investigated the effect of titanium dioxide (TiO2 nanosized particles (NSP and microsized particles (MSP on biophysical surfactant function after direct particle contact and after surface area cycling in vitro. In addition, TiO2 effects on surfactant ultrastructure were visualized. Methods A natural porcine surfactant preparation was incubated with increasing concentrations (50-500 μg/ml of TiO2 NSP or MSP, respectively. Biophysical surfactant function was measured in a pulsating bubble surfactometer before and after surface area cycling. Furthermore, surfactant ultrastructure was evaluated with a transmission electron microscope. Results TiO2 NSP, but not MSP, induced a surfactant dysfunction. For TiO2 NSP, adsorption surface tension (γads increased in a dose-dependent manner from 28.2 ± 2.3 mN/m to 33.2 ± 2.3 mN/m (p min slightly increased from 4.8 ± 0.5 mN/m up to 8.4 ± 1.3 mN/m (p 2 NSP concentrations. Presence of NSP during surface area cycling caused large and significant increases in both γads (63.6 ± 0.4 mN/m and γmin (21.1 ± 0.4 mN/m. Interestingly, TiO2 NSP induced aberrations in the surfactant ultrastructure. Lamellar body like structures were deformed and decreased in size. In addition, unilamellar vesicles were formed. Particle aggregates were found between single lamellae. Conclusion TiO2 nanosized particles can alter the structure and function of pulmonary surfactant. Particle size and surface area respectively play a critical role for the biophysical surfactant response in the lung.

Inhaled Surfactant Therapy in Newborns in Artificial Lung Ventilation

Directory of Open Access Journals (Sweden)

S. A. Perepelitsa

2014-01-01

Full Text Available Objective: to evaluate the efficiency of inhaled surfactant therapy in neonatal infants with respiratory failure.Subjects and methods. The trial enrolled 13 premature neonatal infants; their mean gestational age was 31.8±2.8 weeks and the birth weight was 1825±600.9 g. They had a oneminute Apgar score of 4.3±1.4. All the neonates needed mechanical ventilation (MV atbirth because the leading clinical sign was respiratory failure caused by acute intranatal hypoxia, neonatal amniotic fluid aspiration, respiratory distress syndrome (RDS, and cerebral ischemia. Curosurf was injected in a dose of 174.7±21 mg/kg in the infants with neonatal RDS at 35 minutes of life. All the babies included in the study were noted to have severe disease and prolonged MV. After stabilization of their status, the neonates received combination therapy involving surfactantBL inhalation to reduce the duration of MV. The dose of the agent was 75 mg. Results. After surfactantBL inhalation, effective spontaneous respiration occurred in 69.2% of the newborn infants; successful extubation was carried out. The median duration ofMV after surfactant BL inhalation was 22 hours (4—68 hours. There were no reintubated cases after inhalation therapy. Following surfactantBL inhalation, 4 (30.8% patients remained to be on MV as a control regimen; 3 of them had highfre quency MV. SurfactantBL inhalation made it possible to change the respiratory support regimen and to reduce MV parame ters in these babies. 

Kinetics and mechanism for the sonochemical degradation of a nonionic surfactant.

Science.gov (United States)

Singla, Ritu; Grieser, Franz; Ashokkumar, Muthupandian

2009-03-26

The sonolytic degradation of the nonionic surfactant, octaethylene glycol monododecyl ether (C(12)E(8)), has been studied at various initial concentrations below and above its critical micelle concentration (CMC). It has been observed that the degradation rate increases with an increase in the initial concentration of the surfactant until the CMC is reached. Above the CMC an almost constant degradation rate is observed, suggesting that the surfactant in its monomer form is involved in the degradation process. The degradation process of C(12)E(8) involves two distinct primary processes occurring at the bubble/solution interface: (a) hydroxylation/oxidation of the surfactant and (b) pyrolytic fragmentation of the surfactant. The oxidative cleavage of ethylene oxide units provides evidence for OH radical attack. Hydroxylation of the ethoxy chain gives rise to various short-chain carboxyalkyl-polyethylene glycol intermediates. The polyethylene glycol chain formed, due to the scission of the C(12)E(8) molecule, undergoes rapid hydroxylation/oxidation to yield simple compounds that have the potential to undergo further degradation. The detection of multiple intermediates indicates that several processes affect the complete degradation pathways of the surfactant molecule. TOC analysis, however, indicates that the sonolytic mineralization of the surfactant is difficult to achieve at reasonable rates due to the relatively low surface activity of the degradation products formed during sonolysis.

Surfactant-Enhanced Size-Excluded Transport of Bacteria Through Unsaturated Porous Media.

Science.gov (United States)

Zhu, J.

2017-12-01

US domestic waste water is rich in surfactants because of the intensive usage of surfactants-containing household product. It results in a surfactants presence environment when this untreated waste water released into subsurface. It was reported that surfactants enhance the colloidal transport in porous media, which have significant effect on issues such as subsurface pathogens contamination and biodegradation. In this study, soil column experiments were conducted. The soil column was remained unsaturated and with a steady flow passing through it. Escherichia coli K-12 transported in the soil column and its breakthrough data was collected in presence of surfactant anionic surfactant linear alkylbenzene sulfonate (LAS) concentration range over 0, 0.25, 0.5, 0.75, 1, and 2 times Critical Micelle Concentration (CMC). It was found that the increase in LAS concentration greatly increases breakthrough concentration C/C0 and decreases breakthrough time tb until LAS concentration reaches 1 xCMC. Numerical models were built simulating and investigating this phenomenon. The goodness of model fitting was greatly improved by adding exclusion factor into the model, which indicated that the presence of surfactant might enhance the exclusion effect. The relationships between LAS concentration and the two coefficients, deposition rate coefficient k and exclusion effect coefficient θim, were found can be fitted by a quasi-Langmuir equation. And the model validation with observed data showed that the model has an acceptable reliability.

Biomimetic Fluorocarbon Surfactant Polymers Reduce Platelet Adhesion on PTFE/ePTFE Surfaces

Science.gov (United States)

Wang, Shuwu; Gupta, Anirban Sen; Sagnella, Sharon; Barendt, Pamela M.; Kottke-Marchant, Kandice; Marchant, Roger E.

2010-01-01

We describe a series of fluorocarbon surfactant polymers designed as surface-modifying agents for improving the thrombogenicity of ePTFE vascular graft materials by the reduction of platelet adhesion. The surfactant polymers consist of a poly(vinyl amine) backbone with pendent dextran and perfluoroundecanoyl branches. Surface modification is accomplished by a simple dip-coating process in which surfactant polymers undergo spontaneous surface-induced adsorption and assembly on PTFE/ePTFE surface. The adhesion stability of the surfactant polymer on PTFE was examined under dynamic shear conditions in PBS and human whole blood with a rotating disk system. Fluorocarbon surfactant polymer coatings with three different dextran to perfluorocarbon ratios (1:0.5, 1:1 and 1:2) were compared in the context of platelet adhesion on PTFE/ePTFE surface under dynamic flow conditions. Suppression of platelet adhesion was achieved for all three coated surfaces over the shear-stress range of 0–75 dyn/cm2 in platelet-rich plasma (PRP) or human whole blood. The effectiveness depended on the surfactant polymer composition such that platelet adhesion on coated surfaces decreased significantly with increasing fluorocarbon branch density at 0 dyn/cm2. Our results suggest that fluorocarbon surfactant polymers can effectively suppress platelet adhesion and demonstrate the potential application of the fluorocarbon surfactant polymers as non-thrombogenic coatings for ePTFE vascular grafts. PMID:19323880

Alpha-1-antitrypsin studies: canine serum and canine surfactant protein

International Nuclear Information System (INIS)

Tuttle, W.C.; Slauson, D.O.; Dahlstrom, M.; Gorman, C.

1974-01-01

Canine serum alpha-1-antitrypsin was isolated by gel filtration and affinity chromatography and characterized by polyacrylamide gel electrophoresis and immunoelectrophoresis. Measurement of the trypsin inhibitory capacity of the separated protein indicated a ninefold concentration of functional trypsin inhibitor during the isolation procedure. Electrophoresis demonstrated the presence of a single protein with alpha-globulin mobility and a molecular weight near that of human alpha-1-antitrypsin. The trypsin inhibitory capacity of pulmonary surfactant protein from five Beagle dogs was measured, related to total surfactant protein concentration, and compared with similar measurements on whole serum from the same animals. Results indicated a variable concentration of trypsin inhibitor in the canine pulmonary surfactant protein. However, the concentration in the surfactant protein was always significantly higher than that in the corresponding serum sample. Preliminary experiments designed to separate the trypsin inhibitory fraction(s) from the other surfactant proteins by gel filtration chromatography indicated that the trypsin inhibitor was probably a single protein with a molecular weight near that of alpha-1-antitrypsin. (U.S.)

A review of shampoo surfactant technology: consumer benefits, raw materials and recent developments.

Science.gov (United States)

Cornwell, P A

2018-02-01

Surfactants form the core of all shampoo formulations, and contribute to a wide range of different benefits, including cleansing, foaming, rheology control, skin mildness and the deposition of benefit agents to the hair and scalp. The purpose of this review was to assist the design of effective, modern, shampoo surfactant technologies. The mechanisms through which surfactants help deliver their effects are presented, along with the appraisal techniques through which surfactant options can be tested and screened for product development. The steps that should be taken to select the most appropriate blend of surfactants are described, and useful information on the most widely used surfactants is provided. The review concludes with an examination of recent developments in 'greener' surfactants, 'sulphate-free' technologies and structured liquid phases for novel sensory properties and for suspending benefit agents. © 2017 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Surfactant Effect on the Average Flow Generation Near Curved Interface

Science.gov (United States)

Klimenko, Lyudmila; Lyubimov, Dmitry

2018-02-01

The present work is devoted to the average flow generation near curved interface with a surfactant adsorbed on the surface layer. The investigation was carried out for a liquid drop embedded in a viscous liquid with a different density. The liquid flows inside and outside the drop are generated by small amplitude and high frequency vibrations. Surfactant exchange between the drop surface and the surrounding liquid is limited by the process of adsorption-desorption. It was assumed that the surfactant is soluble in the surrounding liquid, but not soluble in the liquid drop. Surrounding liquid and the liquid in the drop are considered incompressible. Normal and shear viscous stresses balance at the interface is performed under the condition that the film thickness of the adsorbed surfactant is negligible. The problem is solved under assumption that the shape of the drop in the presence of adsorbed surfactant remains spherical symmetry. The effective boundary conditions for the tangential velocity jump and shear stress jump, describing the above generation have been obtained by matched asymptotic expansions method. The conditions under which the drop surface can be considered as a quasi-solid are determined. It is shown that in the case of the significant effect of surfactant on the surface tension, the dominant mechanism for the generation is the Schlichting mechanisms under vibrations.

Induction of virulence gene expression in Staphylococcus aureus by pulmonary surfactant.

Science.gov (United States)

Ishii, Kenichi; Adachi, Tatsuo; Yasukawa, Jyunichiro; Suzuki, Yutaka; Hamamoto, Hiroshi; Sekimizu, Kazuhisa

2014-04-01

We performed a genomewide analysis using a next-generation sequencer to investigate the effect of pulmonary surfactant on gene expression in Staphylococcus aureus, a clinically important opportunistic pathogen. RNA sequence (RNA-seq) analysis of bacterial transcripts at late log phase revealed 142 genes that were upregulated >2-fold following the addition of pulmonary surfactant to the culture medium. Among these genes, we confirmed by quantitative reverse transcription-PCR analysis that mRNA amounts for genes encoding ESAT-6 secretion system C (EssC), an unknown hypothetical protein (NWMN_0246; also called pulmonary surfactant-inducible factor A [PsiA] in this study), and hemolysin gamma subunit B (HlgB) were increased 3- to 10-fold by the surfactant treatment. Among the major constituents of pulmonary surfactant, i.e., phospholipids and palmitate, only palmitate, which is the most abundant fatty acid in the pulmonary surfactant and a known antibacterial substance, stimulated the expression of these three genes. Moreover, these genes were also induced by supplementing the culture with detergents. The induction of gene expression by surfactant or palmitate was not observed in a disruption mutant of the sigB gene, which encodes an alternative sigma factor involved in bacterial stress responses. Furthermore, each disruption mutant of the essC, psiA, and hlgB genes showed attenuation of both survival in the lung and host-killing ability in a murine pneumonia model. These findings suggest that S. aureus resists membrane stress caused by free fatty acids present in the pulmonary surfactant through the regulation of virulence gene expression, which contributes to its pathogenesis within the lungs of the host animal.

Membrane-surfactant interactions. The role of surfactant in mitochondrial complex III-phospholipid-Triton X-100 mixed micelles

International Nuclear Information System (INIS)

Valpuesta, J.M.; Arrondo, J.L.; Barbero, M.C.; Pons, M.; Goni, F.M.

1986-01-01

Complex III (ubiquinol-cytochrome c reductase) was purified from beef heart mitochondria in the form of protein-phospholipid-Triton X-100 mixed micelles (about 1:80:100 molar ratio). Detergent may be totally removed by sucrose density gradient centrifugation, and the resulting lipoprotein complexes retain full enzyme activity. In order to understand the role of surfactant in the mixed micelles, and the interaction of Triton X-100 with integral membrane proteins and phospholipid bilayers, both the protein-lipid-surfactant mixed micelles and the detergent-free lipoprotein system were examined from the point of view of particle size and ultrastructure, enzyme activity, tryptophan fluorescence quenching, 31P NMR, and Fourier transform infrared spectroscopy. The NMR and IR spectroscopic studies show that surfactant withdrawal induces a profound change in phospholipid architecture, from a micellar to a lamellar-like phase. However, electron microscopic observations fail to reveal the existence of lipid bilayers in the absence of detergent. We suggest that, under these conditions, the lipid:protein molar ratio (80:1) is too low to permit the formation of lipid bilayer planes, but the relative orientation and mobility of phospholipids with respect to proteins is similar to that of the lamellar phase. Protein conformational changes are also detected as a consequence of surfactant removal. Fourier transform infrared spectroscopy indicates an increase of peptide beta-structure in the absence of Triton X-100; changes in the amide II/amide I intensity ratio are also detected, although the precise meaning of these observations is unclear

Optimization of surfactant-aided remediation of industrially contaminated soils

International Nuclear Information System (INIS)

Joshi, M.M.; Lee, S.

1996-01-01

Soil matrices contaminated with polycyclic aromatic hydrocarbons (PAHs) abound at the sites of coke-oven gas plants, refineries, and many other major chemical industries. The removal of PAHs from soil using pure water, via soil washing (ex situ) or soil flushing (in situ), is quite ineffective due to their low solubility and hydrophobicity. However, addition of suitable surfactant(s) has been shown to increase the removal efficiency several fold. For the present work, the removal of PAHs occurring in industrially contaminated soil was studied. The objective was to use a nonionic surfactant solution for in situ soil flushing and to evaluate the optimal range of process parameters that can significantly increase the removal efficiency. The process parameters chosen were surfactant concentration, ratio of washing solution volume to soil weight, and temperature of washing solution. These parameters were found to have a significant effect on PAH removal from the contaminated soil and an optimal range was determined for each parameter under given washing conditions

Mechanisms of dynamic wetting failure in the presence of soluble surfactants

Science.gov (United States)

Kumar, Satish; Liu, Chen-Yu; Carvalho, Marcio S.

2017-11-01

A hydrodynamic model and flow visualization experiments are used to understand the mechanisms through which soluble surfactants can influence the onset of dynamic wetting failure. In the model, a Newtonian liquid displaces air in a rectangular channel in the absence of inertia. A Navier-slip boundary condition and constant contact angle are used to describe the dynamic contact line, and surfactants are allowed to adsorb to the interface and moving channel wall (substrate). The Galerkin finite element method is used to calculate steady states and identify the critical capillary number Cacrit at which wetting failure occurs. It is found that surfactant solubility weakens the influence of Marangoni stresses, which tend to promote the onset of wetting failure. The experiments indicate that Cacrit increases with surfactant concentration. For the more viscous solutions used, this behaviour can largely be explained by accounting for changes to the mean surface tension and static contact angle produced by surfactants. For the lowest-viscosity solution used, comparison between the model predictions and experimental observations suggests that other surfactant-induced phenomena such as Marangoni stresses may play a more important role.

Synthesis, surface properties and antimicrobial activity of some germanium nonionic surfactants.

Science.gov (United States)

Zaki, Mohamed F; Tawfik, Salah M

2014-01-01

Esterification reaction between different fatty acid namely; lauric, stearic, oleic and linoleic acids and polyethylene glycol-400 were performed. The produced polyethylene glycol ester were reacted with p-amine benzoic acid followed by condensation reaction with germanium dioxide in presence of sodium carbonate to form desired germinate surfactants. The chemical structures of the synthesized surfactants were determined using different spectra tools. The surface parameter including: the critical micelle concentration (CMC), effectiveness (π(cmc)), efficiency (Pc20), maximum surface excess (Γ(max)) and minimum surface area (A(min)), were calculated from the surface tension measurements. The synthesized surfactants showed higher surface activity. The thermodynamic parameters showed that adsorption and micellization processes are spontaneous. It is clear that the synthesized nonionic surfactants showed their tendency towards adsorption at the interfaces and also micellization in the bulk of their solutions. The synthesized surfactants were tested against different strain of bacteria using inhibition zone diameters. The synthesized surfactants showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative as well as fungi. The promising inhibition efficiency of these compounds against the sulfate reducing bacteria facilitates them to be applicable as new categories of sulfate reducing bacteria biocides.

Mechanisms of polyelectrolyte enhanced surfactant adsorption at the air-water interface.

Science.gov (United States)

Stenger, Patrick C; Palazoglu, Omer A; Zasadzinski, Joseph A

2009-05-01

Chitosan, a naturally occurring cationic polyelectrolyte, restores the adsorption of the clinical lung surfactant Survanta to the air-water interface in the presence of albumin at much lower concentrations than uncharged polymers such as polyethylene glycol. This is consistent with the positively charged chitosan forming ion pairs with negative charges on the albumin and lung surfactant particles, reducing the net charge in the double-layer, and decreasing the electrostatic energy barrier to adsorption to the air-water interface. However, chitosan, like other polyelectrolytes, cannot perfectly match the charge distribution on the surfactant, which leads to patches of positive and negative charge at net neutrality. Increasing the chitosan concentration further leads to a reduction in the rate of surfactant adsorption consistent with an over-compensation of the negative charge on the surfactant and albumin surfaces, which creates a new repulsive electrostatic potential between the now cationic surfaces. This charge neutralization followed by charge inversion explains the window of polyelectrolyte concentration that enhances surfactant adsorption; the same physical mechanism is observed in flocculation and re-stabilization of anionic colloids by chitosan and in alternate layer deposition of anionic and cationic polyelectrolytes on charged colloids.

Assessment of the potential irritation and photoirritation of novel amino acid-based surfactants by in vitro methods as alternative to the animal tests

International Nuclear Information System (INIS)

Benavides, Tomas; Martinez, Veronica; Mitjans, Montserrat; Infante, Maria Rosa; Moran, Carmen; Clapes, Pere; Clothier, Richard; Vinardell, Maria Pilar

2004-01-01

The ultraviolet-A radiation damage effects on skin and eyes will be increased by phototoxic compounds which could be present in pharmaceutical or cosmetic formulations. Great efforts have been made in the last years to find surfactants to replace those with phototoxic potential in commercial use. Series of different in vitro models for phototoxicity, included to validated neutral red uptake (NRU) 3T3 phototoxicity assay are useful screening tools. The phototoxic effects of a novel family of glycerol amino acid-based surfactant compounds were examined via these assays. Human red blood cells and two immortalised cell lines, murine fibroblast cell line 3T3, and one human keratinocyte cell line, HaCaT, were the in vitro models employed to predict potential photoirritation. The phototoxic end-points assessed were hemolysis (human red blood cell test) and resazurin transformation to resorufin and NRU in cell culture methods. The results suggest that no phototoxic effects by any new amino acid derived-surfactants, could be identified

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

International Nuclear Information System (INIS)

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

2016-01-01

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

Surfactants: behavior and some of their applications in the petroleum industry

International Nuclear Information System (INIS)

Rivas, Hercilio; Gutierrez, Xiomara

1999-01-01

The most important theoretical aspect related to the behavior of surfactants in solution and the mechanism which govern the processes of their adsorption at the liquid - liquid, liquid- gas and liquid - solid interfaces are discussed in this paper. The basic principles, which characterize the phase behavior of surfactants in solution are described, and the procedures for stablishing the condition under which surfactants ca be successfully used in basic and applied research activities are given. Finally, the most important aspect of the different processes carried out in the oil industry, with special mention to those in exploration and production, where the surfactants play a very important role, are briefly discussed

Surfactant media for constant-current coulometry. Application for the determination of antioxidants in pharmaceuticals

Energy Technology Data Exchange (ETDEWEB)

Ziyatdinova, Guzel, E-mail: Ziyatdinovag@mail.ru [Analytical Chemistry Department, A.M. Butlerov Institute of Chemistry, Kazan (Volga Region) Federal University, Kremlyevskaya, 18, Kazan 420008 (Russian Federation); Ziganshina, Endzhe; Budnikov, Herman [Analytical Chemistry Department, A.M. Butlerov Institute of Chemistry, Kazan (Volga Region) Federal University, Kremlyevskaya, 18, Kazan 420008 (Russian Federation)

2012-09-26

Highlights: Black-Right-Pointing-Pointer Applicability of surfactants in constant-current coulometry is shown for the first time. Black-Right-Pointing-Pointer Reactions of antioxidants with electrogenerated titrants in surfactant media are investigated. Black-Right-Pointing-Pointer Water insoluble antioxidants can be determined in water media with addition of surfactants. Black-Right-Pointing-Pointer Coulometric determination of antioxidants in pharmaceutical dosage forms using surfactants media is developed. - Abstract: Effect of surfactant presence on electrochemical generation of titrants has been evaluated and discussed for the first time. Cationic (1-dodecylpyridinium and cetylpyridinium bromide), anionic (sodium dodecyl sulfate) and nonionic (Triton X100 and Brij{sup Registered-Sign} 35) surfactants as well as nonionic high molecular weight polymer (PEG 4000) do not react with the electrogenerated bromine, iodine and hexacyanoferrate(III) ions. The electrogenerated chlorine chemically interact with Triton X100 and Brij{sup Registered-Sign} 35. The allowable range of surfactants concentrations providing 100% current yield has been found. Chain-breaking low molecular weight antioxidants (ascorbic acid, rutin, {alpha}-tocopherol and retinol) were determined by reaction with the electrogenerated titrants in surfactant media. Nonionic and cationic surfactants can be used for the determination of antioxidants by reaction with the electrogenerated halogens. On contrary, cationic surfactants gives significantly overstated results of antioxidants determination with electrogenerated hexacyanoferrate(III) ions. The use of surfactants in coulometry of {alpha}-tocopherol and retinol provides their solubilization and allows to perform titration in water media. Simple, express and reliable coulometric approach for determination of {alpha}-tocopherol, rutin and ascorbic acid in pharmaceuticals using surfactant media has been developed. The relative standard deviation of the

Inactivation of pulmonary surfactant due to serum-inhibited adsorption and reversal by hydrophilic polymers: experimental

DEFF Research Database (Denmark)

Taeusch, H William; de la Serna, Jorge Bernardino; Perez-Gil, Jesus

2005-01-01

adsorption of surface active serum proteins. Aqueous suspensions of native porcine surfactant, organic extracts of native surfactant, and the clinical surfactants Curosurf, Infasurf, and Survanta spread on buffered subphases increase the surface pressure, pi, to approximately 40 mN/m within 2 min....... The variation with concentration, temperature, and mode of spreading confirmed Brewster angle microscopy observations that subphase to surface adsorption of surfactant is the dominant form of surfactant transport to the interface. However (with the exception of native porcine surfactant), similar rapid...... increases in pi did not occur when surfactants were applied to subphases containing serum. Components of serum are surface active and adsorb reversibly to the interface increasing pi up to a concentration-dependent saturation value, pi(max). When surfactants were applied to subphases containing serum...

Formation, thermodynamic properties, microstructures and antimicrobial activity of mixed cationic/non-ionic surfactant microemulsions with isopropyl myristate as oil.

Science.gov (United States)

Bardhan, Soumik; Kundu, Kaushik; Das, Sajal; Poddar, Madhumita; Saha, Swapan K; Paul, Bidyut K

2014-09-15

Modification of the interface by blending of surfactants produces considerable changes in the elastic rigidity of the interface, which in turn affects the physicochemical properties of w/o microemulsions. Hence, it could be possible to tune the thermodynamic properties, microstructures and antimicrobial activity of microemulsions by using ionic/non-ionic mixed surfactants and polar lipophilic oil, which are widely used in biologically relevant systems. The present report was aimed at precise characterization of mixed cetyltrimethylammonium bromide and polyoxyethylene (23) lauryl ether microemulsions stabilized in 1-pentanol (Pn) and isopropyl myristate at different physicochemical conditions by employing phase studies, the dilution method, conductivity, DLS, FTIR (with HOD probing) and (1)H NMR measurements. Further, microbiological activities at different compositions were examined against two bacterial strains Bacillus subtilis and Escherichia coli at 303 K. The formation of mixed surfactant microemulsions was found to be spontaneous at all compositions, whereas it was endothermic at equimolar composition. FTIR and (1)H NMR measurements showed the existence of bulk-like, bound and trapped water molecules in confined environments. Interestingly, composition dependence of both highest and lowest inhibitory effects was observed against the bacterial strains, whereas similar features in spontaneity of microemulsion formation were also evidenced. These results suggested a close relationship between thermodynamic stability and antimicrobial activities. Such studies on polar lipophilic oil derived mixed surfactant microemulsions have not been reported earlier. Copyright © 2014 Elsevier Inc. All rights reserved.

Systematic Investigation of the Role of Surfactant Composition and Choice of oil

DEFF Research Database (Denmark)

Schmidt, Signe Tandrup; Neustrup, Malene Aaby; Harloff-Helleberg, Stine

2017-01-01

humoral and CMI responses. METHODS: The influence of emulsion composition was analyzed using a systematic approach. Three factors were varied: i) saturation of the oil phase, ii) type and saturation of the applied surfactant mixture, and iii) surfactant mixture net charge. RESULTS: The emulsions were...... colloidally stable with a droplet diameter of 150-250 nm, and the zeta-potential correlated closely with the net charge of the surfactant mixture. Only cationic emulsions containing the unsaturated surfactant mixture induced concomitant humoral and CMI responses upon immunization of mice with a Ct antigen...

Interaction of biocompatible natural rosin-based surfactants with human serum albumin: A biophysical study

International Nuclear Information System (INIS)

Ishtikhar, Mohd; Ali, Mohd Sajid; Atta, Ayman M.; Al-Lohedan, H.A.; Nigam, Lokesh; Subbarao, Naidu; Hasan Khan, Rizwan

2015-01-01

Biophysical insight into interaction of biocompatible rosin-based surfactants with human serum albumin (HSA) was studied at physiological conditions using various spectroscopic, calorimetric and molecular docking approaches. The binding constant (K b ), enthalpy (ΔH 0 ), entropy (ΔS 0 ) and Gibbs free energy change (ΔG 0 ) were calculated by spectroscopic and calorimetric method. We have also calculated the probability of energy transfer by FRET analysis. The circular dichroism study showed that the cationic surfactant QRMAE significantly altered the secondary structure of HSA as compared to the nonionic rosin surfactants. The thermodynamic study was performed by ITC to determine binding constant as well as change in enthalpy of HSA in presence of rosin surfactants. It clearly showed that hydrogen binding and hydrophobic interaction play an important role in the binding of HSA to rosin surfactants. We have also performed molecular docking studies to locate the binding site on HSA and to visualize the mode of interaction. The present study provides a significant insight into HSA–rosin surfactants interaction, which also improves our understanding of the possible effect of rosin surfactants on human health. - Highlights: • RMPEG 750 has the highest Kb, Kq and Ksv value as compared to other rosin surfactants. • The probability of energy transfer from HSA to rosin surfactants was maximum in the case of RMPEG 750. • Cationic surfactant QRMAE significantly altered the secondary structure of the HSA as compared to other rosin surfactants. • Molecular docking and ITC experiment studies, to locate the binding site on HSA and to investigate the mode of interaction

Study on the surfactants present in atmospheric aerosols collected in the Okinawa Japan

Science.gov (United States)

Kamegawa, A.; Kasaba, T.; Shimabukuro, W.; Arakaki, T.

2017-12-01

The main constituent of atmospheric aerosols is organic substances, which occupy 20 to 70% of the mass. Organic matters in the aerosols contain organic acids, protein and humic acid, which behave similar to surfactants. Since surfactants contain both hydrophobic and hydrophilic functional groups in the molecule, they can play important roles in cloud formation and can affect climate change, but detailed mechanisms and magnitude are not well understood. In addition, surfactants can cause asthma, allergy, dry eye and so on. In this study, our aim is to characterize surfactants in the aerosols collected in different seasons in Okinawa, Japan. Atmospheric aerosols were collected at Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS) during Sep. 2013 and July 2014. Surfactants in the environment are comprised of artificially synthesized compounds and naturally derived organics so we only differentiate them into anionic and cationic surfactants. Colorimetric methods were used to determine the concentrations of anionic surfactants as methylene blue active substance (MBAS). Cationic surfactants were also measured by colorimetric method as disulfine blue active substance (DBAS) and showed always below detection limit. Thus, we only discuss anionic surfactants measured as MBAS. Water soluble organic carbon (WSOC) and metal concentrations were also measured for the same aerosol samples. Concentrations of MBAS in the studied samples were 2-3 times higher in spring, fall and winter than those collected in summer. MBAS concentration in the aerosols showed strong correlation with sulfate ion and WSOC, and slightly weaker correlation with nss-sulfate ion. Among the metals, only sodium ion showed a relatively strong correlation with MBAS concentrations. It is suggested that the anionic surfactants in the studied aerosols are mainly derived from marine sources.

Control of stain geometry by drop evaporation of surfactant containing dispersions.

Science.gov (United States)

Erbil, H Yildirim

2015-08-01

Control of stain geometry by drop evaporation of surfactant containing dispersions is an important topic of interest because it plays a crucial role in many applications such as forming templates on solid surfaces, in ink-jet printing, spraying of pesticides, micro/nano material fabrication, thin film coatings, biochemical assays, deposition of DNA/RNA micro-arrays, and manufacture of novel optical and electronic materials. This paper presents a review of the published articles on the diffusive drop evaporation of pure liquids (water), the surfactant stains obtained from evaporating drops that do not contain dispersed particles and deposits obtained from drops containing polymer colloids and carbon based particles such as carbon nanotubes, graphite and fullerenes. Experimental results of specific systems and modeling attempts are discussed. This review also has some special subtopics such as suppression of coffee-rings by surfactant addition and "stick-slip" behavior of evaporating nanosuspension drops. In general, the drop evaporation process of a surfactant/particle/substrate system is very complex since dissolved surfactants adsorb on both the insoluble organic/inorganic micro/nanoparticles in the drop, on the air/solution interface and on the substrate surface in different extends. Meanwhile, surfactant adsorbed particles interact with the substrate giving a specific contact angle, and free surfactants create a solutal Marangoni flow in the drop which controls the location of the particle deposition together with the rate of evaporation. In some cases, the presence of a surfactant monolayer at the air/solution interface alters the rate of evaporation. At present, the magnitude of each effect cannot be predicted adequately in advance and consequently they should be carefully studied for any system in order to control the shape and size of the final deposit. Copyright © 2014 Elsevier B.V. All rights reserved.

New thermo-sensitive chelating surfactants for selective solvent-free extraction of uranyl nitrate

International Nuclear Information System (INIS)

Prevost, S.; Larpent, C.; Testard, F.; Coulombeau, H.; Baczko, K.; Berthon, L.; Desvaux, H.; Madic, C.; Zemb, T.

2004-01-01

Functional surfactants were synthesised by grafting a chelating group (amino-acid residue) to the tip of a poly-ethoxylated nonionic surfactant chain (C i E j : C i H 2i +1(OCH 2 CH 2 ) j OH)) or in a branched position. C i E j nonionic surfactants are known to be thermo-reversible and to exhibit a clouding phenomenon associated to phase separation of micelles. The functional surfactants retain both surface-active properties, characteristic thermo-reversible behaviour and have efficient complexing properties toward uranyl. In the presence of uranyl nitrate, small micelles are formed at ambient temperature and the de-mixing leads to a separation of the target ion trapped by the functional surfactant (cloud point extraction). Those surfactants are more efficient than mixture of classical C i E j and complexing agent solubilized in the micelles. This reveals a synergistic effect of the covalent bond between the chelating group and the nonionic surfactant C i E j . This paper presents a systematic study of the extraction and aggregation properties and the influence of the nature of the ions. (authors)

The influence of nonionic surfactant Brij 30 on biodegradation of ...

African Journals Online (AJOL)

ONOS

2010-09-06

Sep 6, 2010 ... polluted air stream using biological process is highly efficient and has low ... Brij 30 was the most biodegradable surfactant among Brij 30, Tween 80 and ... The filter material contained surfactants that would enhance the ...

Surfactant from neonatal to pediatric ICU: bench and bedside evidence.

Science.gov (United States)

Boet, A; Brat, R; Aguilera, S S; Tissieres, P; De Luca, D

2014-12-01

Surfactant is a cornerstone of neonatal critical care for the treatment of respiratory distress syndrome of preterm babies. However, other indications have been studied for various clinical conditions both in term neonates and in children beyond neonatal age. A high degree of evidence is not yet available in some cases and this is due to the complex and not yet totally understood physiopathology of the different types of pediatric and neonatal lung injury. We here summarise the state of the art of the bench and bedside knowledge about surfactant use for the respiratory conditions usually cared for in neonatal and pediatric intensive care units. Future research direction will also be presented. On the whole, surfactant is able to improve oxygenation in infection related respiratory failure, pulmonary hemorrhage and meconium aspiration syndrome. Bronchoalveolar lavage with surfactant solution is currently the only means to reduce mortality or need for extracorporeal life support in neonates with meconium aspiration. While surfactant bolus or lavage only improves the oxygenation and ventilatory requirements in other types of postneonatal acute respiratory distress syndrome (ARDS), there seems to be a reduction in the mortality of small infants with RSV-related ARDS.

Activated carbon oxygen content influence on water and surfactant adsorption.

Science.gov (United States)

Pendleton, Phillip; Wu, Sophie Hua; Badalyan, Alexander

2002-02-15

This research investigates the adsorption properties of three activated carbons (AC) derived from coconut, coal, and wood origin. Each carbon demonstrates different levels of resistance to 2 M NaOH treatment. The coconut AC offers the greatest and wood AC the least resistance. The influence of base treatment is mapped in terms of its effects on specific surface area, micropore volume, water adsorption, and dodecanoic acid adsorption from both water and 2 M NaOH solution. A linear relationship exists between the number of water molecules adsorbed at the B-point of the water adsorption isotherm and the oxygen content determined from elemental analysis. Surfactant adsorption isotherms from water and 2 M NaOH indicate that the AC oxygen content effects a greater dependence on affinity for surfactant than specific surface area and micropore volume. We show a linear relationship between the plateau amount of surfactant adsorbed and the AC oxygen content in both water and NaOH phases. The higher the AC oxygen content, the lower the amount of surfactant adsorbed. In contrast, no obvious relationship could be drawn between the surfactant amount adsorbed and the surface area.

Interactions of a zwitterionic thiophene-based conjugated polymer with surfactants

DEFF Research Database (Denmark)

Costa, Telma; De Azevedo, Diego; Stewart, Beverly

2015-01-01

In this paper we investigate the optical and structural properties of a zwitterionic poly[3-(N-(4-sulfonato-1-butyl)-N,N-diethylammonium)hexyl-2,5-thiophene] (P3SBDEAHT) conjugated polyelectrolyte (CPE) and its interaction in water with surfactants, using absorption, photoluminescence (PL......), electrical conductivity, molecular dynamics simulations (MDS) and small-angle X-ray scattering (SAXS). Different surfactants were studied to evaluate the effect of the head group and chain length on the self-assembly. PL data emphasize the importance of polymer-surfactant electrostatic interactions...... in the formation of complexes. Nevertheless, conductivity and MDS data have shown that nonspecific interactions also play an important role. These seem to be responsible for the spatial position of the surfactant tail in the complex and, eventually, for breaking-up P3SBDEAHT aggregates. SAXS measurements on P3...

Effect of alkyl length of cationic surfactants on desorption of Cs from contaminated clay

Energy Technology Data Exchange (ETDEWEB)

Kim, Bo Hyun; Park, Chan Woo; Yang, Hee Man; Seo, Bum Kyoung; Lee, Kune Woo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, So Jin [Chungnam National University, Daejeon (Korea, Republic of)

2017-03-15

In this study, desorption characteristics of Cs from clay according to the hydrophobic alkyl chain length of the cationic surfactant were investigated. Alkyltrimethylammonium bromide was used as a cationic surfactant, and the length of the hydrophobic alkyl chain of the cationic surfactant was varied from –octyl to –cetyl. The adsorbed amount of the cationic surfactant on montmorillonite increased with the length of the hydrophobic alkyl chain, and intercalation of the cationic surfactant into the clay interlayer increased the interlayer distances. The Cs removal efficiency was also enhanced with increasing alkyl chain length, and the cationic surfactant with the cetyl group showed a maximum Cs removal efficiency of 99±2.9%.

(Surfactant + polymer) interaction parameter studied by (liquid + liquid) equilibrium data of quaternary aqueous solution containing surfactant, polymer, and salt

Energy Technology Data Exchange (ETDEWEB)

Foroutan, Masumeh [Physical Chemistry Department, School of Chemistry, College of Science, University of Tehran, 14155-6455 Tehran (Iran, Islamic Republic of)], E-mail: foroutan@khayam.ut.ac.ir; Heidari, Nosrat; Mohammadlou, Maryam [Chemistry Department, Faculty of Science, Uremia University, Uremia (Iran, Islamic Republic of); Sojahrood, Amin Jafari [Physics Department, Faculty of Science, Uremia University, Uremia (Iran, Islamic Republic of)

2009-02-15

(Liquid + liquid) equilibrium (LLE) data of quaternary aqueous system containing polyoxyethylene (20) cetyl ether (with abbreviation name Brij 58, non-ionic surfactant), diammonium hydrogen phosphate, and poly ethylene glycol (PEG) with three molar masses {l_brace}M{sub W} = (1000, 6000, and 35,000) g . mol{sup -1}{r_brace} have been determined experimentally at T = 313.15 K. Furthermore, the Flory-Huggins theory with two electrostatic terms (Debye-Hueckel and Pitzer-Debye-Hueckel equations) have been used to calculate the phase behavior of the quaternary systems and (surfactant + polymer) interaction parameter as well as interaction parameters between other species. Temperature dependency of the parameters of the Flory-Huggins theory has been obtained. Also an effort have been done to show that addition of PEG as well as increasing the temperature can shift the binodal curves of the ternary aqueous system containing surfactant and salt to lower mole fraction of salt. Also the effect of polymer molar mass on the binodal diagram displacement has been discussed.

The Effect of Surfactants on Gas-Liquid Pipe Flows

NARCIS (Netherlands)

Van Nimwegen, A.T.

2015-01-01

Liquid loading is a major problem in the natural gas industry, in which gas production is limited by the accumulation of liquids in the well tubing. Liquid loading can be prevented by the injection of surfactants at the bottom of the well. The surfactants cause the liquid in the well to foam,

An investigation of bubble coalescence and post-rupture oscillation in non-ionic surfactant solutions using high-speed cinematography.

Science.gov (United States)

Bournival, G; Ata, S; Karakashev, S I; Jameson, G J

2014-01-15

Most processes involving bubbling in a liquid require small bubbles to maximise mass/energy transfer. A common method to prevent bubbles from coalescing is by the addition of surfactants. In order to get an insight into the coalescence process, capillary bubbles were observed using a high speed cinematography. Experiments were performed in solutions of 1-pentanol, 4-methyl-2-pentanol, tri(propylene glycol) methyl ether, and poly(propylene glycol) for which information such as the coalescence time and the deformation of the resultant bubble upon coalescence was extracted. It is shown in this study that the coalescence time increases with surfactant concentration until the appearance of a plateau. The increase in coalescence time with surfactant concentration could not be attributed only to surface elasticity. The oscillation of the resultant bubble was characterised by the damping of the oscillation. The results suggested that a minimum elasticity is required to achieve an increased damping and considerable diffusion has a detrimental effect on the dynamic response of the bubble, thereby reducing the damping. Copyright © 2013 Elsevier Inc. All rights reserved.

Surfactant-nanotube interactions in water and nanotube separation by diameter: atomistic simulations

Science.gov (United States)

Carvalho, E. J. F.; Dos Santos, M. C.

2010-05-01

A non-destructive sorting method to separate single-walled carbon nanotubes (SWNTs) by diameter was recently proposed. By this method, SWNTs are suspended in water by surfactant encapsulation and the separation is carried out by ultracentrifugation in a density gradient. SWNTs of different diameters are distributed according to their densities along the centrifuge tube. A mixture of two anionic surfactants, namely sodium dodecylsulfate (SDS) and sodium cholate (SC), presented the best performance in discriminating nanotubes by diameter. Unexpectedly, small diameter nanotubes are found at the low density part of the centrifuge tube. We present molecular dynamics studies of the water-surfactant-SWNT system to investigate the role of surfactants in the sorting process. We found that surfactants can actually be attracted towards the interior of the nanotube cage, depending on the relationship between the surfactant radius of gyration and the nanotube diameter. The dynamics at room temperature showed that, as the amphiphile moves to the hollow cage, water molecules are dragged together, thereby promoting the nanotube filling. The resulting densities of filled SWNT are in agreement with measured densities.

Microwave-assisted nonionic surfactant extraction of aliphatic hydrocarbons from petroleum source rock

Energy Technology Data Exchange (ETDEWEB)

Akinlua, A., E-mail: geochemresearch@yahoo.com [Fossil Fuels and Environmental Geochemistry Group, Department of Chemistry, Obafemi Awolowo University, Ile-Ife (Nigeria); Jochmann, M.A.; Laaks, J.; Ewert, A.; Schmidt, T.C. [Instrumental Analytical Chemistry, University Duisburg-Essen, Universitaetsstr, 5, 45141 Essen (Germany)

2011-04-08

The extraction of aliphatic hydrocarbons from petroleum source rock using nonionic surfactants with the assistance of microwave was investigated and the conditions for maximum yield were determined. The results showed that the extraction temperatures and kinetic rates have significant effects on extraction yields of aliphatic hydrocarbons. The optimum temperature for microwave-assisted nonionic surfactant extraction of aliphatic hydrocarbons from petroleum source rock was 105 deg. C. The optimum extraction time for the aliphatic hydrocarbons was at 50 min. Concentration of the nonionic surfactant solution and irradiation power had significant effect on the yields of aliphatic hydrocarbons. The yields of the analytes were much higher using microwave assisted nonionic surfactant extraction than with Soxhlet extraction. The recoveries of the n-alkanes and acyclic isoprenoid hydrocarbons for GC-MS analysis from the extractant nonionic surfactant solution by in-tube extraction (ITEX 2) with a TENAX TA adsorbent were found to be efficient. The results show that microwave-assisted nonionic surfactant extraction (MANSE) is a good and efficient green analytical preparatory technique for geochemical evaluation of petroleum source rock.

Microwave-assisted nonionic surfactant extraction of aliphatic hydrocarbons from petroleum source rock

International Nuclear Information System (INIS)

Akinlua, A.; Jochmann, M.A.; Laaks, J.; Ewert, A.; Schmidt, T.C.

2011-01-01

The extraction of aliphatic hydrocarbons from petroleum source rock using nonionic surfactants with the assistance of microwave was investigated and the conditions for maximum yield were determined. The results showed that the extraction temperatures and kinetic rates have significant effects on extraction yields of aliphatic hydrocarbons. The optimum temperature for microwave-assisted nonionic surfactant extraction of aliphatic hydrocarbons from petroleum source rock was 105 deg. C. The optimum extraction time for the aliphatic hydrocarbons was at 50 min. Concentration of the nonionic surfactant solution and irradiation power had significant effect on the yields of aliphatic hydrocarbons. The yields of the analytes were much higher using microwave assisted nonionic surfactant extraction than with Soxhlet extraction. The recoveries of the n-alkanes and acyclic isoprenoid hydrocarbons for GC-MS analysis from the extractant nonionic surfactant solution by in-tube extraction (ITEX 2) with a TENAX TA adsorbent were found to be efficient. The results show that microwave-assisted nonionic surfactant extraction (MANSE) is a good and efficient green analytical preparatory technique for geochemical evaluation of petroleum source rock.

Surfactive stabilization of multi-walled carbon nanotube dispersions with dissolved humic substances

Energy Technology Data Exchange (ETDEWEB)

Chappell, Mark A. [Environmental Laboratory, Engineering Research and Development Center, US Army Corps of Engineers, 3909 Halls Ferry Road, Vicksburg, MS 39180 (United States)], E-mail: mark.a.chappell@usace.army.mil; George, Aaron J.; Dontsova, Katerina M.; Porter, Beth E. [SpecPro, Inc., 4815 Bradford Drive, Suite 201, Huntsville, AL 35805 (United States); Price, Cynthia L. [Environmental Laboratory, Engineering Research and Development Center, US Army Corps of Engineers, 3909 Halls Ferry Road, Vicksburg, MS 39180 (United States); Zhou Pingheng; Morikawa, Eizi [J. Bennett Johnston Sr. Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, LA 70806 (United States); Kennedy, Alan J.; Steevens, Jeffery A. [Environmental Laboratory, Engineering Research and Development Center, US Army Corps of Engineers, 3909 Halls Ferry Road, Vicksburg, MS 39180 (United States)

2009-04-15

Soil humic substances (HS) stabilize carbon nanotube (CNT) dispersions, a mechanism we hypothesized arose from the surfactive nature of HS. Experiments dispersing multi-walled CNT in solutions of dissolved Aldrich humic acid (HA) or water-extractable Catlin soil HS demonstrated enhanced stability at 150 and 300 mg L{sup -1} added Aldrich HA and Catlin HS, respectively, corresponding with decreased CNT mean particle diameter (MPD) and polydispersivity (PD) of 250 nm and 0.3 for Aldrich HA and 450 nm and 0.35 for Catlin HS. Analogous trends in MPD and PD were observed with addition of the surfactants Brij 35, Triton X-405, and SDS, corresponding to surfactant sorption maximum. NEXAFS characterization showed that Aldrich HA contained highly surfactive domains while Catlin soil possessed a mostly carbohydrate-based structure. This work demonstrates that the chemical structure of humic materials in natural waters is directly linked to their surfactive ability to disperse CNT released into the environment. - Suspensions of multi-walled carbon nanotubes are stabilized by relatively low concentrations of dissolved humic substances in solution through surfactive mechanisms.

Surfactive stabilization of multi-walled carbon nanotube dispersions with dissolved humic substances

International Nuclear Information System (INIS)

Chappell, Mark A.; George, Aaron J.; Dontsova, Katerina M.; Porter, Beth E.; Price, Cynthia L.; Zhou Pingheng; Morikawa, Eizi; Kennedy, Alan J.; Steevens, Jeffery A.

2009-01-01

Soil humic substances (HS) stabilize carbon nanotube (CNT) dispersions, a mechanism we hypothesized arose from the surfactive nature of HS. Experiments dispersing multi-walled CNT in solutions of dissolved Aldrich humic acid (HA) or water-extractable Catlin soil HS demonstrated enhanced stability at 150 and 300 mg L -1 added Aldrich HA and Catlin HS, respectively, corresponding with decreased CNT mean particle diameter (MPD) and polydispersivity (PD) of 250 nm and 0.3 for Aldrich HA and 450 nm and 0.35 for Catlin HS. Analogous trends in MPD and PD were observed with addition of the surfactants Brij 35, Triton X-405, and SDS, corresponding to surfactant sorption maximum. NEXAFS characterization showed that Aldrich HA contained highly surfactive domains while Catlin soil possessed a mostly carbohydrate-based structure. This work demonstrates that the chemical structure of humic materials in natural waters is directly linked to their surfactive ability to disperse CNT released into the environment. - Suspensions of multi-walled carbon nanotubes are stabilized by relatively low concentrations of dissolved humic substances in solution through surfactive mechanisms

Increased drop formation frequency via reduction of surfactant interactions in flow-focusing microfluidic devices.

Science.gov (United States)

Josephides, Dimitris N; Sajjadi, Shahriar

2015-01-27

Glass capillary based microfluidic devices are able to create extremely uniform droplets, when formed under the dripping regime, at low setup costs due to their ease of manufacture. However, as they are rarely parallelized, simple methods to increase droplet production from a single device are sought. Surfactants used to stabilize drops in such systems often limit the maximum flow rate that highly uniform drops can be produced due to the lowering interfacial tension causing jetting. In this paper we show that by simple design changes we can limit the interactions of surfactants and maximize uniform droplet production. Three flow-focused configurations are explored: a standard glass capillary device (consisting of a single round capillary inserted into a square capillary), a nozzle fed device, and a surfactant shielding device (both consisting of two round capillaries inserted into either end of a square capillary). In principle, the maximum productivity of uniform droplets is achieved if surfactants are not present. It was found that surfactants in the standard device greatly inhibit droplet production by means of interfacial tension lowering and tip-streaming phenomena. In the nozzle fed configuration, surfactant interactions were greatly limited, yielding flow rates comparable to, but lower than, a surfactant-free system. In the surfactant shielding configuration, flow rates were equal to that of a surfactant-free system and could make uniform droplets at rates an order of magnitude above the standard surfactant system.

Screening and Optimization of Bio surfactant Production by the Hydrocarbon-Degrading Bacteria

International Nuclear Information System (INIS)

Ainon Hamzah; Noramiza Sabturani; Shahidan Radiman

2013-01-01

Bio surfactants are amphiphilic compounds produced by microorganisms as secondary metabolite. The unique properties of bio surfactants make them possible to replace or to be added to synthetic surfactants which are mainly used in food, cosmetics and pharmaceutical industries and in environmental applications. In this study twenty hydrocarbon-degrading bacteria were screened for bio surfactant production. All of the bacterial isolates were grown in mineral salt medium (MSM) with addition of 1 % (v/v) Tapis crude oil as carbon source. The presence of bio surfactant was determined by the drop-collapse test, microplate analysis, oil spreading technique, emulsification index (%EI24) and surface tension measurement. Only one isolate, Pseudomonas aeruginosa UKMP14T, was found to be positive for all the qualitative tests and reducing the surface tension of the medium to 49.5 dynes/ with emulsification index of 25.29 %. This isolate produced bio surfactant optimally at pH 9.0 and incubation temperature of 37 degree Celsius. Furthermore, P. aeruginosa UKMP14T when grown in MSM with addition of 1 % (v/v) glycerol and 1.3 g/ L ammonium sulphate with C/N ratio 14:1 produced bio surfactant with percentage of surface tension reduction at 55 % or 30.6 dynes/ cm with %EI24 of 43 %. This percentage of surface tension reduction represents an increasing reduction in surface tension of medium by 39 % over the value before optimization. This study showed that P. aeruginosa UKMP14T has the ability to biodegrade hydrocarbon and concurrently produce bio surfactant. (author)

Study of surfactant-free microemulsions and microemulsions with fatty acid salts

OpenAIRE

Marcus, Julien

2016-01-01

This thesis deals with the study of microemulsions and is composed of two main parts. In the first part, surfactant-free microemulsions are studied, whereas in the second part microemulsions with surfactants and cosurfactants are investigated. Over the last few years, surfactant-free microemulsions became a major topic at our institute and were thoroughly studied using the reference system water/ethanol/1-octanol. As explained later in the Fundamentals part (see section 1.2), fluctuating ...

Impact of the New Generation Reconstituted Surfactant CHF5633 on Human CD4+ Lymphocytes.

Directory of Open Access Journals (Sweden)

Markus Fehrholz

Full Text Available Natural surfactant preparations, commonly isolated from porcine or bovine lungs, are used to treat respiratory distress syndrome in preterm infants. Besides biophysical effectiveness, several studies have documented additional immunomodulatory properties. Within the near future, synthetic surfactant preparations may be a promising alternative. CHF5633 is a new generation reconstituted synthetic surfactant preparation with defined composition, containing dipalmitoyl-phosphatidylcholine, palmitoyl-oleoyl-phosphatidylglycerol and synthetic analogs of surfactant protein (SP- B and SP-C. While its biophysical effectiveness has been demonstrated in vitro and in vivo, possible immunomodulatory abilities are currently unknown.The aim of the current study was to define a potential impact of CHF5633 and its single components on pro- and anti-inflammatory cytokine responses in human CD4+ lymphocytes.Purified human CD4+ T cells were activated using anti CD3/CD28 antibodies and exposed to CHF5633, its components, or to the well-known animal-derived surfactant Poractant alfa (Curosurf®. Proliferative response and cell viability were assessed using flow cytometry and a methylthiazolyldiphenyltetrazolium bromide colorimetric assay. The mRNA expression of IFNγ, IL-2, IL-17A, IL-22, IL-4, and IL-10 was measured by quantitative PCR, while intracellular protein expression was assessed by means of flow cytometry.Neither CHF5633 nor any of its phospholipid components with or without SP-B or SP-C analogs had any influence on proliferative ability and viability of CD4+ lymphocytes under the given conditions. IFNγ, IL-2, IL-17A, IL-22, IL-4, and IL-10 mRNA as well as IFNγ, IL-2, IL-4 and IL-10 protein levels were unaffected in both non-activated and activated CD4+ lymphocytes after exposure to CHF5633 or its constituents compared to non-exposed controls. However, in comparison to Curosurf®, expression levels of anti-inflammatory IL-4 and IL-10 mRNA were

Interaction of biocompatible natural rosin-based surfactants with human serum albumin: A biophysical study

Energy Technology Data Exchange (ETDEWEB)

Ishtikhar, Mohd [Protein Biophysics Laboratory, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002 (India); Ali, Mohd Sajid [Surfactant Research Chair, Department of Chemistry, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Atta, Ayman M. [Surfactant Research Chair, Department of Chemistry, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Petroleum Application department, Egyptian Petroleum Research Institute, Ahmad Elzomor St., Nasr city, Cairo-11727 (Egypt); Al-Lohedan, H.A. [Surfactant Research Chair, Department of Chemistry, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Nigam, Lokesh; Subbarao, Naidu [Centre for Computational Biology and Bioinformatics, School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi 110067 (India); Hasan Khan, Rizwan, E-mail: rizwanhkhan@hotmail.com [Protein Biophysics Laboratory, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002 (India)

2015-11-15

Biophysical insight into interaction of biocompatible rosin-based surfactants with human serum albumin (HSA) was studied at physiological conditions using various spectroscopic, calorimetric and molecular docking approaches. The binding constant (K{sub b}), enthalpy (ΔH{sup 0}), entropy (ΔS{sup 0}) and Gibbs free energy change (ΔG{sup 0}) were calculated by spectroscopic and calorimetric method. We have also calculated the probability of energy transfer by FRET analysis. The circular dichroism study showed that the cationic surfactant QRMAE significantly altered the secondary structure of HSA as compared to the nonionic rosin surfactants. The thermodynamic study was performed by ITC to determine binding constant as well as change in enthalpy of HSA in presence of rosin surfactants. It clearly showed that hydrogen binding and hydrophobic interaction play an important role in the binding of HSA to rosin surfactants. We have also performed molecular docking studies to locate the binding site on HSA and to visualize the mode of interaction. The present study provides a significant insight into HSA–rosin surfactants interaction, which also improves our understanding of the possible effect of rosin surfactants on human health. - Highlights: • RMPEG 750 has the highest Kb, Kq and Ksv value as compared to other rosin surfactants. • The probability of energy transfer from HSA to rosin surfactants was maximum in the case of RMPEG 750. • Cationic surfactant QRMAE significantly altered the secondary structure of the HSA as compared to other rosin surfactants. • Molecular docking and ITC experiment studies, to locate the binding site on HSA and to investigate the mode of interaction.

Surfactant Apoprotein D in Preterm Neonates with Acute Respiratory Distress Syndrome

Directory of Open Access Journals (Sweden)

S. A. Perepelitsa

2009-01-01

Full Text Available Objective: to study the production of surfactant apoprotein D in preterm neonates with acute respiratory distress syndrome (ARDS during artificial ventilation (AV. Subjects and methods. The paper presents the results of studying the production of surfactant protein D (SP-D in various biological fluids in 44 preterm neonates. Two groups of newborn infants were identified according to the clinical manifestations of ARDS. The study group comprised 25 infants with the severe course of the disease, in this connection the preventive administration of the exogenous surfactant Curosurf and AV were made in all the neonates at birth. The control group included 19 preterm babies without signs of ARDS. Results. The study has demonstrated that in parturients and preterm neonatal infants, surfactant apoprotein D is detectable in various biological fluids: amniotic fluid, the gastric aspirate obtained just after birth, residual umbilical cord blood, serum following 8 hours of birth, and bronchoalveolar fluid. Despite the low gestational age of the neonates, the lung surfactant system is able to produce SP-D, as evidenced by its high content in the amniotic fluid and residual umbilical cord blood of preterm neonates. The production of apoprotein D in preterm neonates considerably reduces in the next few hours after birth. Conclusion. The findings suggest that fetal tissues generate SP-D, which improves pulmonary gas exchange in preterm neonates in the first hours after birth and that alveolar-capillary membrane dysfunctions are transient in the neonates on AV. Key words: preterm neonates, acute respiratory distress syndrome, surfactant, surfactant apoprotein D.

Adsorption of surfactants on sand surface in enhanced oil recovery: Isotherms, kinetics and thermodynamic studies

Energy Technology Data Exchange (ETDEWEB)

Bera, Achinta; Kumar, T.; Ojha, Keka; Mandal, Ajay, E-mail: mandal_ajay@hotmail.com

2013-11-01

Adsorption of surfactants onto reservoir rock surface may result in the loss and reduction of their concentrations in surfactant flooding, which may render them less efficient or ineffective in practical applications of enhanced oil recovery (EOR) techniques. Surfactant flooding for EOR received attraction due to its ability to increase the displacement efficiency by lowering the interfacial tension between oil and water and mobilizing the residual oil. This article highlights the adsorption of surfactants onto sand surface with variation of different influencing factors. It has been experimentally found that adsorption of cationic surfactant on sand surface is more and less for anionic surfactant, while non-ionic surfactant shows intermediate behaviour. X-ray diffraction (XRD) study of clean sand particles has been made to determine the main component present in the sand particles. The interaction between sand particles and surfactant has been studied by Fourier Transform Infrared (FTIR) Spectroscopy of the sand particles before and after aging with surfactant. Salinity plays an important role in adsorption of anionic surfactant. Batch experiments were also performed to understand the effects of pH and adsorbent dose on the sorption efficiency. The sand particles exhibited high adsorption efficiency at low pH for anionic and nonionic surfactants. But opposite trend was found for cationic surfactant. Adsorption data were analyzed by fitting with Langmuir, Freundlich, Redlich-Peterson, and Sips isotherm models. Results show that the Langmuir isotherm and pseudo-second order kinetics models suit the equilibrium and kinetics of adsorption on sand surface. Thermodynamics feasibility of the adsorption process was also studied to verify the spontaneity of the process.

Evaluation of bacterial surfactant toxicity towards petroleum degrading microorganisms.

Science.gov (United States)

Lima, Tânia M S; Procópio, Lorena C; Brandão, Felipe D; Leão, Bruna A; Tótola, Marcos R; Borges, Arnaldo C

2011-02-01

The acute toxicity of bacterial surfactants LBBMA111A, LBBMA155, LBBMA168, LBBMA191 and LBBMA201 and the synthetic surfactant sodium dodecyl sulfate (SDS) on the bioluminescent bacterium Vibrio fischeri was evaluated by measuring the reduction of light emission (EC(20)) by this microorganism when exposed to different surfactant concentrations. Moreover, the toxic effects of different concentrations of biological and synthetic surfactants on the growth of pure cultures of isolates Acinetobacter baumannii LBBMA04, Acinetobacter junni LBBMA36, Pseudomonas sp. LBBMA101B and Acinetobacter baumanni LBBMAES11 were evaluated in mineral medium supplemented with glucose. The EC(20) values obtained confirmed that the biosurfactants have a significantly lower toxicity to V. fischeri than the SDS. After 30 min of exposure, bacterial luminescence was almost completely inhibited by SDS at a concentration of 4710 mg L(-1). Growth reduction of pure bacterial cultures caused by the addition of biosurfactants to the growth medium was lower than that caused by SDS. Copyright © 2010 Elsevier Ltd. All rights reserved.

Factors affecting responses of infants with respiratory distress syndrome to exogenous surfactant therapy.

Science.gov (United States)

Ho, N K

1993-02-01

Approximately 20% to 30% of infants with respiratory distress syndrome (RDS) do not respond to surfactant replacement therapy. Unfortunately there is no uniform definition of 'response' or 'non-response' to surfactant therapy. Response was based on improvement in a/A PO2 and/or mean airway pressure (MAP) by some and on improvement in FIO2 and/or MAP by others. Even the point of time at which evaluation of response was done is different in various reports. There is an urgent need to adopt an uniform definition. Most premature babies are surfactant deficient which is the aetiological factor of RDS. Generally good antenatal care and perinatal management are essential in avoidance of premature birth. Babies with lung hypoplasia and who are extremely premature (less than 24 weeks of gestation) do not respond well to exogenous surfactant replacement because of structural immaturity. Prompt management of asphyxiated birth and shock are necessary as there may be negative response to surfactant replacement. Foetal exposure to glucocorticoids improves responsiveness to postnatal administration of surfactant. Antenatal steroid therapy has become an important part of management of RDS with surfactant replacement. The premature lungs with high alveolar permeability tend to develop pulmonary oedema. With the presence of plasma-derived surfactant inhibitors, the response to exogenous surfactant may be affected. These inhibitors may also be released following ventilator barotrauma. The standard of neonatal intensive care such as ventilatory techniques has an important bearing on the outcome of the RDS babies.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth Mechanism of Gold Nanorods in Binary Surfactant System

Energy Technology Data Exchange (ETDEWEB)

Kim, Bo-Mi; Seo, Sun-Hwa; Joe, Ara; Shim, Kyu-Dong; Jang, Eue-Soon [Kumoh National Institute of Technology, Gumi (Korea, Republic of)

2016-06-15

In order to reveal the growth mechanism of gold nanorods (GNRs) in a binary surfactant system, we synthesized various GNRs by changing the concentration of the surfactants, AgNO{sub 3}, and HBr in the growth solution. We found that the benzyldime thylhexadecylammoniumchloride surfactant had weak interaction with the gold ions, but it could reduce the membrane fluidity. In addition, we could dramatically decrease the cetyltrimethylammonium bromide concentration required for GNR growth by adding an HBr solution. Notably, Ag{sup +} ions were necessary to break the symmetry of the seed crystals for GNR growth, but increasing the concentration of Ag{sup +} and Br{sup -} ions caused a decrease in the template size.

Atomistic simulations of surfactant adsorption kinetics at interfaces

Science.gov (United States)

Iskrenova, Eugeniya; Patnaik, Soumya

2014-03-01

Heat transfer control and enhancement is an important and challenging problem in a variety of industrial and technological applications including aircraft thermal management. The role of additives in nucleate boiling and phase change in general has long been recognized and studied experimentally and modeled theoretically but in-depth description and atomistic understanding of the multiscale processes involved are still needed for better prediction and control of the heat transfer efficiency. Surfactant additives have been experimentally observed to either enhance or inhibit the boiling heat transfer depending on the surfactant concentration and chemistry and, on a molecular level, their addition leads to dynamic surface tension and changes in interfacial and transfer properties, thus contributing to the complexity of the problem. We present our atomistic modeling study of the interfacial adsorption kinetics of aqueous surfactant (sodium dodecyl sulfate) systems at a range of concentrations at room and boiling temperatures. Classical molecular dynamics and Umbrella Sampling simulations were used to study the surfactant transport properties and estimate the adsorption and desorption rates at liquid-vacuum and liquid-solid interfaces. The authors gratefully acknowledge funding from AFOSR Thermal Science Program and the Air Force Research Laboratory DoD Supercomputing Resource Center for computing time and resources.

Effect of Surfactants on Plasmid DNA Stability and Release from ...

African Journals Online (AJOL)

Purpose: To evaluate the effect of surfactants on plasmid DNA during preparation and release from polylactic glycolide (PLGA) microspheres. Methods: Various surfactants, both ionic and non-ionic (Span, Tween, Triton X100, cetyltrimethylammonium bromide and sodium dodecyl sulphate), were added during the ...

Spectral behaviour of eosin Y in different solvents and aqueous surfactant media

Science.gov (United States)

Chakraborty, Moumita; Panda, Amiya Kumar

2011-10-01

Photophysical behaviour of the anionic xanthene dye, eosin Y (EY) was investigated in solvents of different polarities as well as in the presence of aqueous cationic surfactants. From the correlation between ET(30) and Kosower Z values of EY in different solvents, subsequent parameters for EY were determined in the presence of surfactants. A red shift, both in the absorption and emission spectra of EY, was observed with decreasing solvent polarity. Dimerisation of EY was found to be dependent on solvent polarity. Cationic surfactants retarded the process of dimerisation, which were evident from the lower dimerisation constant ( KD) values, compared to that of in pure water. Dye-surfactant interaction constants were determined at different temperatures (298-318 K) and subsequently the thermodynamic parameters, viz., Δ G°, Δ H° and Δ S° were evaluated using the interaction constant values. The fluorescence spectra of EY followed the same trend as in the absorption spectra, although with lesser extents. Stokes shifts were calculated and correlated with the polarity of the medium. Fluorescence of EY was initially quenched by the cationic surfactants in their pre-micellar region, which then followed a red shift with intensity enhancement. Fluorescence quenching was found to be of Stern-Volmer type where the excited state lifetime of EY remained unchanged in different surfactant media. However, the anisotropy value of EY was changed in the post micellar region of surfactants.

Mathematical Modelling of Surfactant Self-assembly at Interfaces

KAUST Repository

Morgan, C. E.

2015-01-01

© 2015 Society for Industrial and Applied Mathematics. We present a mathematical model to describe the distribution of surfactant pairs in a multilayer structure beneath an adsorbed monolayer. A mesoscopic model comprising a set of ordinary differential equations that couple the rearrangement of surfactant within the multilayer to the surface adsorption kinetics is first derived. This model is then extended to the macroscopic scale by taking the continuum limit that exploits the typically large number of surfactant layers, which results in a novel third-order partial differential equation. The model is generalized to allow for the presence of two adsorbing boundaries, which results in an implicit free-boundary problem. The system predicts physically observed features in multilayer systems such as the initial formation of smaller lamellar structures and the typical number of layers that form in equilibrium.

Molecular self assembly of mixed comb-like dextran surfactant polymers for SPR virus detection.

Science.gov (United States)

Mai-Ngam, Katanchalee; Kiatpathomchai, Wansika; Arunrut, Narong; Sansatsadeekul, Jitlada

2014-11-04

The synthesis of two comb-like dextran surfactant polymers, that are different in their dextran molecular weight (MW) distribution and the presence of carboxylic groups, and their characterization are reported. A bimodal carboxylic dextran surfactant polymer consists of poly(vinyl amine) (PVAm) backbone with carboxyl higher MW dextran, non-functionalized lower MW dextran and hydrophobic hexyl branches; while a monomodal dextran surfactant polymer is PVAm grafted with non-functionalized lower MW dextran and hexyl branches. Layer formation of non-covalently attached dextran chains with bimodal MW distributions on a surface plasmon resonance (SPR) chip was investigated from the perspective of mixed physisorption of the bimodal and monomodal surfactant polymers. Separation distances between the carboxylic longer dextran side chains within the bimodal surfactant polymer and between the whole bimodal surfactant molecules on the chip surface could be well-controlled. SPR analysis of shrimp yellow head virus using our mixed surfactant chips showed dependence on synergetic adjustment of these separation distances. Copyright © 2014 Elsevier Ltd. All rights reserved.

Small-angle neutron scattering studies of nonionic surfactant: Effect

Indian Academy of Sciences (India)

Micellar solution of nonionic surfactant -dodecyloligo ethyleneoxide surfactant, decaoxyethylene monododecyl ether [CH3(CH2)11(OCH2CH2)10OH], C12E10 in D2O solution have been analysed by small-angle neutron scattering (SANS) at different temperatures (30, 45 and 60°C) both in the presence and absence of ...

Surfactant adsorption and aggregate structure of silica nanoparticles: a versatile stratagem for the regulation of particle size and surface modification

International Nuclear Information System (INIS)

Chaudhary, Savita; Rohilla, Deepak; Mehta, S K

2014-01-01

The area of silica nanoparticles is incredibly polygonal. Silica particles have aroused exceptional deliberation in bio-analysis due to great progress in particular arenas, for instance, biocompatibility, unique properties of modifiable pore size and organization, huge facade areas and pore volumes, manageable morphology and amendable surfaces, elevated chemical and thermal stability. Currently, silica nanoparticles participate in crucial utilities in daily trade rationales such as power storage, chemical and genetic sensors, groceries dispensation and catalysis. Herein, the size-dependent interfacial relation of anionic silica nanoparticles with twelve altered categories of cationic surfactants has been carried out in terms of the physical chemical facets of colloid and interface science. The current analysis endeavours to investigate the virtual consequences of different surfactants through the development of the objective composite materials. The nanoparticle size controls, the surface-to-volume ratio and surface bend relating to its interaction with surfactant will also be addressed in this work. More importantly, the simulated stratagem developed in this work can be lengthened to formulate core–shell nanostructures with functional nanoparticles encapsulated in silica particles, making this approach valuable and extensively pertinent for employing sophisticated materials for catalysis and drug delivery. (papers)

Removal of cationic surfactant (CTAB from aqueous solution on to activated carbon obtained from corncob.

Directory of Open Access Journals (Sweden)

S. M. Yakout

2009-05-01

Full Text Available Direct and indirect releases of large quantities of surfactants to the environment may result in serious health and environmental problems. Therefore, surfactants should be removed from water before water is released to the environment or delivered for public use. Using powdered activated carbon (PAC as adsorbent may be an effective technique to remove surfactants. In this study, the removal of surfactants by PAC was investigated and the influencesof the operating parameters on the effectiveness on adsorption rate were studied. Cationic surfactant, Cetyl trimethyl ammonium bromide (CTAB was selected for the experiments. A series of batch experiments were performed to determine the sorption isotherms of surfactants to PAC. The results showed that carbon structure affect mainly on the surfactant adsorption. Surfactant equilibrium data fitted very well to the binary langmuir model. The pseudo first-,second- order and intraparticle diffusion kinetic models were applied. Both, the external mass transfer and intraparticle diffusion mechanisms involve in CTAB sorption.

Composition, structure and mechanical properties define performance of pulmonary surfactant membranes and films

DEFF Research Database (Denmark)

Ortiz, Elisa Parra; Perez-Gil, Jesús

2015-01-01

of breathing and avoiding alveolar collapse, especially at the end of expiration. The goal of the present review is to summarize current knowledge regarding the structure, lipid-protein interactions and mechanical features of surfactant membranes and films and how these properties correlate with surfactant...... biological function inside the lungs. Surfactant mechanical properties can be severely compromised by different agents, which lead to surfactant inhibition and ultimately contributes to the development of pulmonary disorders and pathologies in newborns, children and adults. A detailed comprehension...

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

Science.gov (United States)

Kennedy, Ross A; Kennedy, Michelle L

2007-03-30

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

Contrast media inhibit exogenous surfactant therapy in rats with acute respiratory distress syndrome

NARCIS (Netherlands)

Kesecioglu, Jozef; Haitsma, Jack J.; Schultz, Marcus J.; den Heeten, Gerard J.; Lachmann, Burkhard

2006-01-01

AIM: To test the effects of various contrast media on the pulmonary surfactant system. MATERIAL AND METHODS: In a rat model of acute respiratory distress syndrome (ARDS) induced by lung lavage, the effects of surfactant suspended in saline were compared with surfactant suspended in the contrast

Essential Regulation of Lung Surfactant Homeostasis by the Orphan G Protein-Coupled Receptor GPR116

Directory of Open Access Journals (Sweden)

Mi Young Yang

2013-05-01

Full Text Available GPR116 is an orphan seven-pass transmembrane receptor whose function has been unclear. Global disruption of the Gpr116 gene in mice revealed an unexpected, critical role for this receptor in lung surfactant homeostasis, resulting in progressive accumulation of surfactant lipids and proteins in the alveolar space, labored breathing, and a reduced lifespan. GPR116 expression analysis, bone marrow transplantation studies, and characterization of conditional knockout mice revealed that GPR116 expression in ATII cells is required for maintaining normal surfactant levels. Aberrant packaging of surfactant proteins with lipids in the Gpr116 mutant mice resulted in compromised surfactant structure, function, uptake, and processing. Thus, GPR116 plays an indispensable role in lung surfactant homeostasis with important ramifications for the understanding and treatment of lung surfactant disorders.

Cleaning by Surfactant Gradients: Particulate Removal from Porous Materials and the Significance of Rinsing in Laundry Detergency

Science.gov (United States)

Shin, Sangwoo; Warren, Patrick B.; Stone, Howard A.

2018-03-01

Removing particles from fibrous materials involves loosening via surfactants followed by particle transfer in a flow. While flow advection is commonly believed to be the major driver for pore-scale transport, small pores within the fabric do not allow any significant fluid flow inside them, thus significantly reducing the role of advection. However, rinsing the fabric with fresh water naturally establishes a surfactant gradient within the pore space, providing a suitable environment for particles to undergo diffusiophoresis. We demonstrate that this mechanism can remove particles from deep within fabric pores at an accelerated rate. The nonlinear aspect of diffusiophoresis significantly prolongs the lifetime of the phoretic motion beyond the naive solute diffusion time scale during rinsing, allowing long-lasting, continuous removal of particles. Moreover, owing to the fine balance between chemiphoresis and electrophoresis for particles in anionic surfactant concentration gradients, we show that the particle removal is sensitive to the counterion mobility, suggesting a simple route to control the effect. We thus claim to have resolved the "stagnant core problem"—a long-standing mystery in laundry detergency—and have identified a physicochemical approach to particle transport in fibrous media with broad applicability.

Effect of the Presence of Nonionic Surfactant Brij35 on the Mobility of Metribuzin in Soil

Directory of Open Access Journals (Sweden)

Eman M. ElSayed

2013-04-01

Full Text Available Given the water scarcity becoming endemic to a large portion of the globe, arid region irrigation has resorted to the use of treated, partially treated, or even untreated wastewaters. Such waters contain a number of pollutants, including surfactants. Applied to agricultural lands, these surfactants could affect the fate and transport of other chemicals in the soil, particularly pesticides. A field lysimeter study was undertaken to investigate the effect of nonionic surfactant, Brij35, on the in-soil fate and transport of a commonly used herbicide, metribuzin [4-amino-6-tert-butyl-3-(methylthio-1,2,4-triazin-5(4H-one]. Nine PVC lysimeters, 1.0 m long × 0.45 m diameter, were packed with a sandy soil to a bulk density of 1.35 mg m−3. Antibiotic-free cattle manure was applied (10 mg ha−1 at the surface of the lysimeters. Metribuzin was then applied to the soil surface of all lysimeters at a rate of 1.00 kg a.i. ha−1. Each of three aqueous Brij35 solutions, 0, 0.5 and 5 mg L−1 (i.e., “good”, “poor” and “very poor” quality irrigation water were each applied to the lysimeters in triplicate. Analysis for metribuzin residues in samples of both soil and leachate, collected over a 90-day period, showed the surfactant Brij35 to have increased the mobility of metribuzin in soil, indicating that continued use of poor quality water could influence pesticide transport in agricultural soils, and increase the risk of groundwater contamination.

Enhanced oil recovery with surfactant flooding

Energy Technology Data Exchange (ETDEWEB)

Buelow Sandersen, S.

2012-05-15

Understanding the underlying mechanisms of systems that exhibit liquid-liquid equilibrium (e.g. oil-brine systems) at reservoir conditions is an area of increasing interest within EOR. This is true both for complex surfactant systems as well as for oil and brine systems. It is widely accepted that an increase in oil recovery can be obtained through flooding, whether it is simple waterflooding, waterflooding where the salinity has been modified by the addition or removal of specific ions (socalled ''smart'' waterflooding) or surfactant flooding. High pressure experiments have been carried out in this work on a surfactant system (surfactant/ oil/ brine) and on oil/ seawater systems (oil/ brine). The high pressure experiments were carried out on a DBR JEFRI PVT cell, where a glass window allows observation of the phase behavior of the different systems at various temperatures and pressures inside the high pressure cell. Phase volumes can also be measured visually through the glass window using precision equipment. The surfactant system for which an experimental study was carried out consisted of the mixture heptane, sodium dodecyl sulfate (SDS)/ 1-butanol/ NaCl/ water. This system has previously been examined at ambient pressures and temperatures but this has been extended here to pressures up to 400 bar and to slightly higher temperatures (40 deg. C, 45 deg. C and 50 deg. C). Experiments were performed at constant salinity (6.56 %), constant surfactant-alcohol ratio (SAR) but with varying water-oil ratios (WOR). At all temperatures it was very clear that the effect of pressure was significant. The system changed from the two phase region, Winsor II, to the three phase region, Winsor III, as pressure increased. Increasing pressures also caused a shift from the three phase region (Winsor III), to a different two phase region, (Winsor I). These changes in equilibrium phase behavior were also dependent on the composition of the system. A number of

Effect of surfactant for magnetic properties of iron oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Haracz, S. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Hilgendorff, M. [Freie Universität Berlin, Fachbereich Physik, Arnimalle 14, 14195 Berlin (Germany); Rybka, J.D. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Giersig, M. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Freie Universität Berlin, Fachbereich Physik, Arnimalle 14, 14195 Berlin (Germany)

2015-12-01

Highlights: • Dynamic behavior of magnetic nanoparticles. • Synthesis of iron oxide nanoparticles. • Effect of surfactant for magnetic properties. - Abstract: For different medical applications nanoparticles (NPs) with well-defined magnetic properties have to be used. Coating ligand can change the magnetic moment on the surface of nanostructures and therefore the magnetic behavior of the system. Here we investigated magnetic NPs in a size of 13 nm conjugated with four different kinds of surfactants. The surface anisotropy and the magnetic moment of the system were changed due to the presence of the surfactant on the surface of iron oxide NPs.

The benefits of paid employment among persons with common mental health problems: Evidence for the selection and causation mechanism

NARCIS (Netherlands)

M. Schuring (Merel); S.J.W. Robroek (Suzan); A. Burdorf (Alex)

2017-01-01

textabstractObjectives The aims of this study were to (i) investigate the impact of paid employment on self-rated health, self-esteem, mastery, and happiness among previously unemployed persons with common mental health problems, and (ii) determine whether there are educational inequalities in these

Common symptoms in middle aged women: their relation to employment status, psychosocial work conditions and social support in a Swedish setting.

Science.gov (United States)

Krantz, G; Ostergren, P O

2000-03-01

Over the past few decades there has been a growing interest among researchers, in women's overall life circumstances and their relation to women's health status. For example, paid employment has been considered an important part of women's living conditions in Western societies as the number of women entering the labour market has grown constantly over the past decades. When comparing men's and women's health, one of the most consistent findings is a higher rate of symptoms among women. The most commonly reported symptoms in women are depressive symptoms, symptoms of bodily tension and chronic pain from muscles and joints. The aim of this study was to investigate whether socioeconomic factors, employment status, psychosocial work conditions and social network/support are associated with middle aged women's health status in terms of common symptoms. A mailed questionnaire was used in a cross sectional design assessing socioeconomic factors, employment status, psychosocial work conditions according to the demand/control model, social network/support and an index based on the 15 most frequent symptoms presented by middle aged women when seeking health care. A rural community with 13,200 inhabitants in the western part of Sweden. Women were randomly selected from the general population in the study area, 40 to 50 years of age. The response rate was 81.7 per cent. Women who were non-employed had a significantly increased odds of a high level of common symptoms (OR = 2.82; 95% confidence intervals 1.69, 4.70), as well as women exposed to job strain (OR = 3.27; 1.92, 5.57), independently of the level of social network/support. Furthermore, exposure to low social support, low social anchorage or low social participation independently showed significantly increased odds of a high level of common symptoms (OR = 2.75; 1.71, 4.42; OR = 2.91; 1.81, 4.69 and OR = 1.69; 1.10, 2.61, respectively). Work related factors, such as non-employment and job strain, and circumstances

Employing Common Limit Range Property to Prove Unified Metrical Common Fixed Point Theorems

Directory of Open Access Journals (Sweden)

Mohammad Imdad

2013-01-01

Full Text Available The purpose of this paper is to emphasize the role of “common limit range property” to ascertain the existence of common fixed point in metric spaces satisfying an implicit function essentially due to the paper of Ali and Imdad (2008. As an application to our main result, we derive a fixed point theorem for four finite families of self-mappings which can be utilized to derive common fixed point theorems involving any finite number of mappings. Our results improve and extend a host of previously known results including the ones contained in the paper of Ali and Imdad (2008. We also furnish some illustrative examples to support our main results.

Interactions of short chain phenylalkanoic acids within ionic surfactant micelles in aqueous media

Directory of Open Access Journals (Sweden)

Naeem Kashif

2012-01-01

Full Text Available % SDS KR nema Solubilization and interactions of phenylalkanoic acids induced by cationic surfactant, cetyltrimethylammonium bromide (CTAB and an anionic surfactant, sodium dodecyl sulfate (SDS was investigated spectrophotometrically at 25.0°C. The UV spectra of the additives (acids were measured with and without surfactant above and below critical micelle concentration (cmc of the surfactant. The presence of alkyl chain in phenylalkanoic acids is responsible for hydrophobic interaction resulting in shift of the spectra towards longer wavelength (red shift. The value of partition coefficient (Kx between the bulk water and surfactant micelles and in turn standard free energy change of solubilization (ΔGpº were also estimated by measuring the differential absorbance (ΔA of the additives in micellar solutions.

Investigations of the kinetics of surfactant-assisted growth of cobalt/copper multilayers

Science.gov (United States)

Peterson, Brennan Lovelace

Surfactants---a term given to a broad family of surface additives used in thin film growth---provide a potentially useful tool for the deposition engineer. A long history of work on the field has produced a sometimes conflicting view of what surfactants do, and while their efficacy in improving magnetic films is well established, the attendant structural changes remain unclear. Early work on surfactant-assisted growth was generally confined to deposition at near equilibrium conditions: high temperature and very slow deposition rates on very smooth (single crystal) substrates. In the case of low temperature sputter deposition, the kinetic phenomena differ greatly from the near-equilibrium case: high rate, more interlayer diffusive pathways, high grain boundary density, and few well defined atomic steps. There are two major ideas which underlie and explain the use of surfactants. First, they are used to alter growth kinetics of a single material by changing the diffusion barriers on the growing surface. Second, surfactants alter the initial nucleation parameters in heteroepitaxial growth, which is often explained with reference to changes in the surface energy, gamma. Changes to these parameters result, in turn, to variations of the roughness and conformality of thin films grown with the assistance of surfactants. Finally, the roughness and conformality are critical for determining the performance of modern thin film magnetic sensors. As surfactants offer a way to alter the nucleation and growth kinetics, they offer tremendous potential benefits. However, before surfactants are trustworthy deposition tool, a better understanding of their structural effects and underlying surface energy and kinetic changes is necessary. In order to investigate these phenomena, DC magnetron sputtered [Co/Cu] multilayers were deposited on Si/SiO2 substrates using O2 , Ag, Pb, and In as surfactants. Oxygen was introduced during growth at partial pressures ranging from 10-9 to 10-6 Torr

Desorption of organophosphorous pesticides from soil with wastewater and surfactant solutions

International Nuclear Information System (INIS)

Hernandez-Soriano, M. C.; Mingorance, M. D.; Pena, A.

2009-01-01

Surfactants can be introduced in the environment by wastewater discharge, point-charge pollution or deliberate action, e. g. to remediate contaminated soil or groundwater. The irrigation of soil with wastewater containing surfactants may modify pesticide desorption from soil, thus affecting their affecting their environmental fate. Desorption from soil of the plain of Granada (South-eastern Spain) of two organophosphorous pesticides, diazinon and dimethoate, differing in solubility and hydrophobicity, has been evaluated in the presence of different surfactant aqueous solutions and municipal wastewater. (Author)

Summer/winter variability of the surfactants in aerosols from Grenoble, France

Science.gov (United States)

Baduel, Christine; Nozière, Barbara; Jaffrezo, Jean-Luc

2012-02-01

Many atmospheric aerosols seem to contain strong organic surfactants likely to enhance their cloud-forming properties. Yet, few techniques allow for the identification and characterization of these compounds. Recently, we introduced a double extraction method to isolate the surfactant fraction of atmospheric aerosol samples, and evidenced their very low surface tension (≤30 mN m -1). In this work, this analytical procedure was further optimized. In addition to an optimized extraction and a reduction of the analytical time, the improved method led to a high reproducibility in the surface tension curves obtained (shapes and minimal values), illustrated by the low uncertainties on the values, ±10% or less. The improved method was applied to PM 10 aerosols from the urban area of Grenoble, France collected from June 2009 to January 2010. Significant variability was observed between the samples. The minimum surface tension obtained from the summer samples was systematically lower (30 mN m -1) than that of the winter samples (35-45 mN m -1). Sharp transitions in the curves together with the very low surface tensions suggested that the dominating surfactants in the summer samples were biosurfactants, which would be consistent with the high biogenic activity in that season. One group of samples from the winter also displayed sharp transitions, which, together with the slightly higher surface tension, suggested the presence of weaker, possibly man-made, surfactants. A second group of curves from the winter did not display any clear transition but were similar to those of macromolecular surfactants such as polysaccharides or humic substances from wood burning. These surfactants are thus likely to originate from wood burning, the dominating source for aerosols in Grenoble in winter. These observations thus confirm the presence of surfactants from combustion processes in urban aerosols reported by other groups and illustrates the ability of our method to distinguish between

Micelle formation of nonionic surfactants in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate: surfactant chain length dependence of the critical micelle concentration.

Science.gov (United States)

Inoue, Tohru; Yamakawa, Haruka

2011-04-15

Micellization behavior was investigated for polyoxyethylene-type nonionic surfactants with varying chain length (C(n)E(m)) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)). Critical micelle concentration (cmc) was determined from the variation of (1)H NMR chemical shift with the surfactant concentration. The logarithmic value of cmc decreased linearly with the number of carbon atoms in the surfactant hydrocarbon chain, similarly to the case observed in aqueous surfactant solutions. However, the slope of the straight line is much smaller in bmimBF(4) than in aqueous solution. Thermodynamic parameters for micelle formation estimated from the temperature dependence of cmc showed that the micellization in bmimBF(4) is an entropy-driven process around room temperature. This behavior is also similar to the case in aqueous solution. However, the magnitude of the entropic contribution to the overall micellization free energy in bmimBF(4) is much smaller compared with that in aqueous solution. These results suggest that the micellization in bmimBF(4) proceeds through a mechanism similar to the hydrophobic interaction in aqueous surfactant solutions, although the solvophobic effect in bmimBF(4) is much weaker than the hydrophobic effect. Copyright © 2011 Elsevier Inc. All rights reserved.

Surfactant effect on functionalized carbon nanotube coated snowman-like particles and their electro-responsive characteristics

Energy Technology Data Exchange (ETDEWEB)

Zhang, Ke; Liu, Ying Dan [Department of Polymer Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of); Choi, Hyoung Jin, E-mail: hjchoi@inha.ac.kr [Department of Polymer Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of)

2012-10-15

The core–shell structured snowman-like (SL) microparticles coated by functionalized multi-walled carbon nanotube (MWNT) were prepared in the presence of different surfactants including cationic surfactant-cetyl trimethylammonium bromide (CTAB) and anionic surfactant-sodium lauryl sulfate (SDS). The effect of surfactants on adsorption onto SL particles was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and conductivity. The cationic surfactant is found to be more effective than anionic surfactant for helping nanotube adsorbed onto microparticle due to the presence of electrostatic interaction between the functionalized MWNT and the surfactant. Furthermore, the MWNT/SL particles dispersed in silicone oil exhibited a typical fibril structure of the electrorheological characteristics under an applied electric field observed by an optical microscope (OM), in which the state of nanotubes wrapped on the particles strongly affects their electro-responsive characteristics.

Surfactant effect on functionalized carbon nanotube coated snowman-like particles and their electro-responsive characteristics

International Nuclear Information System (INIS)

Zhang, Ke; Liu, Ying Dan; Choi, Hyoung Jin

2012-01-01

The core–shell structured snowman-like (SL) microparticles coated by functionalized multi-walled carbon nanotube (MWNT) were prepared in the presence of different surfactants including cationic surfactant-cetyl trimethylammonium bromide (CTAB) and anionic surfactant-sodium lauryl sulfate (SDS). The effect of surfactants on adsorption onto SL particles was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and conductivity. The cationic surfactant is found to be more effective than anionic surfactant for helping nanotube adsorbed onto microparticle due to the presence of electrostatic interaction between the functionalized MWNT and the surfactant. Furthermore, the MWNT/SL particles dispersed in silicone oil exhibited a typical fibril structure of the electrorheological characteristics under an applied electric field observed by an optical microscope (OM), in which the state of nanotubes wrapped on the particles strongly affects their electro-responsive characteristics.

Surfactant Ligand Removal and Rational Fabrication of Inorganically Connected Quantum Dots

KAUST Repository

Zhang, Haitao

2011-12-14

A novel method is reported to create inorganically connected nanocrystal (NC) assemblies for both II-VI and IV-VI semiconductors by removing surfactant ligands using (NH 4) 2S. This surface modification process differs from ligand exchange methods in that no new surfactant ligands are introduced and the post-treated NC surfaces are nearly bare. The detailed mechanism study shows that the high reactivity between (NH 4) 2S and metal-surfactant ligand complexes enables the complete removal of surfactant ligands in seconds and converts the NC metal-rich shells into metal sulfides. The post-treated NCs are connected through metal-sulfide bonding and form a larger NCs film assembly, while still maintaining quantum confinement. Such "connected but confined" NC assemblies are promising new materials for electronic and optoelectronic devices. © 2011 American Chemical Society.

Adsorption of hydrophobic organic compounds onto a hydrophobic carbonaceous geosorbent in the presence of surfactants.

Science.gov (United States)

Wang, Peng; Keller, Arturo A

2008-06-01

The adsorption of hydrophobic organic compounds (HOCs; atrazine and diuron) onto lampblack was studied in the presence of nonionic, cationic, and anionic surfactants (Triton(R) X-100), benzalkonium chloride [BC], and linear alkylbenzene sulfonate [LAS]) to determine the effect of the surfactant on HOC adsorption onto a hydrophobic carbonaceous geosorbent. Linear alkylbenzene sulfonate showed an adsorption capacity higher than that of BC but similar to that of Triton X-100, implying the charge property of a surfactant is not a useful indicator for predicting the surfactant's adsorption onto a hydrophobic medium. The results also indicated that the octanol-water partition coefficient (K(OW)) of a surfactant is not a good predictor of that surfactant's sorption onto a hydrophobic medium. Under subsaturation adsorption conditions (i.e., before sorption saturation is reached), surfactant adsorption reduced HOC adsorption to a significant extent, with the reduction in HOC adsorption increasing monotonically with the amount of surfactant adsorbed. Among the three surfactants, Triton X-100 was the most effective in reducing HOC adsorption, whereas BC and LAS showed similar effectiveness in this regard. Under the same amount of the surfactant sorbed, the reduction in atrazine adsorption was consistently greater than that for diuron because of atrazine's lower hydrophobicity. No significant difference was observed in the amount of the HOC adsorbed under different adsorption sequences. Our results showed that the presence of surfactant can significantly decrease HOC adsorption onto hydrophobic environmental media and, thus, is important in predicting HOC fate and transport in the environment.

A Novel Aqueous Micellar Two-Phase System Composed of Surfactant and Sorbitol for Purification of Pectinase Enzyme from Psidium guajava and Recycling Phase Components

Science.gov (United States)

Murshid, Fara Syazana; Manap, Mohd Yazid; Hussin, Muhaini

2015-01-01

A novel aqueous two-phase system composed of a surfactant and sorbitol was employed for the first time to purify pectinase from Psidium guajava. The influences of different parameters, including the type and concentration of the surfactant and the concentration and composition of the surfactant/sorbitol ratio, on the partitioning behavior and recovery of pectinase were investigated. Moreover, the effects of system pH and the crude load on purification fold and the yield of purified pectinase were studied. The experimental results indicated that the pectinase was partitioned into surfactant-rich top phase, and the impurities were partitioned into the sorbitol-rich bottom phase with the novel method involving an ATPS composed of 26% (w/w) Triton X-100 and 23% (w/w) sorbitol at 54.2% of the TLL crude load of 20% (w/w) at pH 6.0. The enzyme was successfully recovered by this method with a high purification factor of 15.2 and a yield of 98.3%, whereas the phase components were also recovered and recycled at rates above 96%. This study demonstrated that this novel ATPS method can be used as an efficient and economical alternative to the traditional ATPS for the purification and recovery of the valuable enzyme. PMID:25756051

A novel aqueous micellar two-phase system composed of surfactant and sorbitol for purification of pectinase enzyme from Psidium guajava and recycling phase components.

Science.gov (United States)

Amid, Mehrnoush; Murshid, Fara Syazana; Manap, Mohd Yazid; Hussin, Muhaini

2015-01-01

A novel aqueous two-phase system composed of a surfactant and sorbitol was employed for the first time to purify pectinase from Psidium guajava. The influences of different parameters, including the type and concentration of the surfactant and the concentration and composition of the surfactant/sorbitol ratio, on the partitioning behavior and recovery of pectinase were investigated. Moreover, the effects of system pH and the crude load on purification fold and the yield of purified pectinase were studied. The experimental results indicated that the pectinase was partitioned into surfactant-rich top phase, and the impurities were partitioned into the sorbitol-rich bottom phase with the novel method involving an ATPS composed of 26% (w/w) Triton X-100 and 23% (w/w) sorbitol at 54.2% of the TLL crude load of 20% (w/w) at pH 6.0. The enzyme was successfully recovered by this method with a high purification factor of 15.2 and a yield of 98.3%, whereas the phase components were also recovered and recycled at rates above 96%. This study demonstrated that this novel ATPS method can be used as an efficient and economical alternative to the traditional ATPS for the purification and recovery of the valuable enzyme.

Early CPAP versus surfactant in extremely preterm infants.

Science.gov (United States)

Finer, Neil N; Carlo, Waldemar A; Walsh, Michele C; Rich, Wade; Gantz, Marie G; Laptook, Abbot R; Yoder, Bradley A; Faix, Roger G; Das, Abhik; Poole, W Kenneth; Donovan, Edward F; Newman, Nancy S; Ambalavanan, Namasivayam; Frantz, Ivan D; Buchter, Susie; Sánchez, Pablo J; Kennedy, Kathleen A; Laroia, Nirupama; Poindexter, Brenda B; Cotten, C Michael; Van Meurs, Krisa P; Duara, Shahnaz; Narendran, Vivek; Sood, Beena G; O'Shea, T Michael; Bell, Edward F; Bhandari, Vineet; Watterberg, Kristi L; Higgins, Rosemary D

2010-05-27

There are limited data to inform the choice between early treatment with continuous positive airway pressure (CPAP) and early surfactant treatment as the initial support for extremely-low-birth-weight infants. We performed a randomized, multicenter trial, with a 2-by-2 factorial design, involving infants who were born between 24 weeks 0 days and 27 weeks 6 days of gestation. Infants were randomly assigned to intubation and surfactant treatment (within 1 hour after birth) or to CPAP treatment initiated in the delivery room, with subsequent use of a protocol-driven limited ventilation strategy. Infants were also randomly assigned to one of two target ranges of oxygen saturation. The primary outcome was death or bronchopulmonary dysplasia as defined by the requirement for supplemental oxygen at 36 weeks (with an attempt at withdrawal of supplemental oxygen in neonates who were receiving less than 30% oxygen). A total of 1316 infants were enrolled in the study. The rates of the primary outcome did not differ significantly between the CPAP group and the surfactant group (47.8% and 51.0%, respectively; relative risk with CPAP, 0.95; 95% confidence interval [CI], 0.85 to 1.05) after adjustment for gestational age, center, and familial clustering. The results were similar when bronchopulmonary dysplasia was defined according to the need for any supplemental oxygen at 36 weeks (rates of primary outcome, 48.7% and 54.1%, respectively; relative risk with CPAP, 0.91; 95% CI, 0.83 to 1.01). Infants who received CPAP treatment, as compared with infants who received surfactant treatment, less frequently required intubation or postnatal corticosteroids for bronchopulmonary dysplasia (Pneonatal outcomes did not differ significantly between the two groups. The results of this study support consideration of CPAP as an alternative to intubation and surfactant in preterm infants. (ClinicalTrials.gov number, NCT00233324.) 2010 Massachusetts Medical Society

Template-less surfactant-free hydrothermal synthesis NiO nanoflowers and their photoelectrochemical hydrogen production

KAUST Repository

Qurashi, Ahsanulhaq

2015-12-01

A facile direct surfactant-free template-less hydrothermal method is employed for the growth of high surface-area NiO nanoflowers made up of complex and assembled nanosheets network.Field emission scanning electron microscopy revealed that each nanosheet is about 50-60nm thick. Detailed structural analysis reveals single-crystalline nature of NiO nanoflowers with cubic crystal structure. The optical absorption bands in the wavelength range of 350-800nm illustrated in terms of ligand field theory. The photoelectrochemical (PEC), water splitting performance on the NiO nanoflowers were also investigated. © 2015 Hydrogen Energy Publications, LLC.

Template-less surfactant-free hydrothermal synthesis NiO nanoflowers and their photoelectrochemical hydrogen production

KAUST Repository

Qurashi, Ahsanulhaq; Zhang, Zhongai; Asif, M.; Yamazaki, Toshinari

2015-01-01

A facile direct surfactant-free template-less hydrothermal method is employed for the growth of high surface-area NiO nanoflowers made up of complex and assembled nanosheets network.Field emission scanning electron microscopy revealed that each nanosheet is about 50-60nm thick. Detailed structural analysis reveals single-crystalline nature of NiO nanoflowers with cubic crystal structure. The optical absorption bands in the wavelength range of 350-800nm illustrated in terms of ligand field theory. The photoelectrochemical (PEC), water splitting performance on the NiO nanoflowers were also investigated. © 2015 Hydrogen Energy Publications, LLC.

Are Level of Education and Employment Related to Symptoms of Common Mental Disorders in Current and Retired Professional Footballers?

NARCIS (Netherlands)

Gouttebarge, Vincent; Aoki, Haruhito; Verhagen, Evert; Kerkhoffs, Gino

2016-01-01

Mental disorders have become a topic of increasing interest in research due to their serious consequences for quality of life and functioning. The objective of this study was to explore the relationship of level of education, employment status and working hours with symptoms of common mental

The application of a mulch biofilm barrier for surfactant enhanced polycyclic aromatic hydrocarbon bioremediation

International Nuclear Information System (INIS)

Seo, Youngwoo; Lee, Woo-Hyung; Sorial, George; Bishop, Paul L.

2009-01-01

Lab scale mulch biofilm barriers were constructed and tested to evaluate their performance for preventing the migration of aqueous and surfactant solubilized PAHs. The spatial distribution of viable PAH degrader populations and resultant biofilm formation were also monitored to evaluate the performance of the biobarrier and the prolonged surfactant effect on the PAH degrading microorganism consortia in the biobarrier. Sorption and biodegradation of PAHs resulted in stable operation of the system for dissolved phenanthrene and pyrene during 150 days of experimentation. The nonionic surfactant could increase the solubility of phenanthrene and pyrene significantly. However, the biobarrier itself couldn't totally prevent the migration of micellar solubilized phenanthrene and pyrene. The presence of surfactant and the resultant highly increased phenanthrene or pyrene concentration didn't appear to cause toxic effects on the attached biofilm in the biobarrier. However, the presence of surfactant did change the structural composition of the biofilm. - Mulch biofilm barrier showed potential for surfactant enhanced bioremediation, and the presence of surfactant changed the structural composition of the biofilm

Surfactant induced flows in thin liquid films : an experimental study

NARCIS (Netherlands)

Sinz, D.K.N.

2012-01-01

The topic of the experimental work summarized in my thesis is the flow in thin liquid films induced by non-uniformly distributed surfactants. The flow dynamics as a consequence of the deposition of a droplet of an insoluble surfactant onto a thin liquid film covering a solid substrate where

Nonionic surfactant Brij35 effects on toluene biodegradation in a ...

African Journals Online (AJOL)

Nonionic surfactant effects on the toluene dissolved in the water phase and biodegradation kinetic behaviors of toluene in a composite bead biofilter were investigated. The toluene dissolved in the water phase was enhanced by the addition of surfactant into aqueous solution and the enhancing effect was more pronounced ...

Effects of surfactant micelles on viscosity and conductivity of poly(ethylene glycol) solutions

Science.gov (United States)

Wang, Shun-Cheng; Wei, Tzu-Chien; Chen, Wun-Bin; Tsao, Heng-Kwong

2004-03-01

The neutral polymer-micelle interaction is investigated for various surfactants by viscometry and electrical conductometry. In order to exclude the well-known necklace scenario, we consider aqueous solutions of low molecular weight poly(ethylene glycol) (2-20)×103, whose radial size is comparable to or smaller than micelles. The single-tail surfactants consist of anionic, cationic, and nonionic head groups. It is found that the viscosity of the polymer solution may be increased several times by micelles if weak attraction between a polymer segment and a surfactant exists, ɛsurfactant concentration is therefore attributed to the considerable cross links among micelles and polymers (transient network). In addition to substantial alteration of the transport properties, this weak interaction also influences the onset point of thermodynamic instability associated with polymer-surfactant solutions. The examples include the decrease of critical aggregation concentration for ionic surfactant and clouding point for nonionic surfactant due to PEG addition.

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

Science.gov (United States)

Zhong, Xin; Duan, Fei

2015-05-19

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

Characterization of the host–guest complex of a curcumin analog with β-cyclodextrin and β-cyclodextrin–gemini surfactant and evaluation of its anticancer activity

Directory of Open Access Journals (Sweden)

Poorghorban M

2015-01-01

Full Text Available Masoomeh Poorghorban,1 Umashankar Das,2 Osama Alaidi,1 Jackson M Chitanda,2 Deborah Michel,1 Jonathan Dimmock,1 Ronald Verrall,3 Pawel Grochulski,1,4 Ildiko Badea1 1Drug Discovery and Development Research Group, College of Pharmacy and Nutrition, 2Department of Chemical and Biological Engineering, 3Department of Chemistry, University of Saskatchewan, Saskatoon, SK, Canada; 4Canadian Light Source, Saskatoon, SK, Canada Background: Curcumin analogs, including the novel compound NC 2067, are potent cytotoxic agents that suffer from poor solubility, and hence, low bioavailability. Cyclodextrin-based carriers can be used to encapsulate such agents. In order to understand the interaction between the two molecules, the physicochemical properties of the host–guest complexes of NC 2067 with β-cyclodextrin (CD or β-cyclodextrin–gemini surfactant (CDgemini surfactant were investigated for the first time. Moreover, possible supramolecular structures were examined in order to aid the development of new drug delivery systems. Furthermore, the in vitro anticancer activity of the complex of NC 2067 with CDgemini surfactant nanoparticles was demonstrated in the A375 melanoma cell line.Methods: Physicochemical properties of the complexes formed of NC 2067 with CD or CDgemini surfactant were investigated by synchrotron-based powder X-ray diffraction, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. Synchrotron-based small- and wide-angle X-ray scattering and size measurements were employed to assess the supramolecular morphology of the complex formed by NC 2067 with CDgemini surfactant. Lastly, the in vitro cell toxicity of the formulations toward A375 melanoma cells at various drug-to-carrier mole ratios were measured by cell viability assay.Results: Physical mixtures of NC 2067 and CD or CDgemini surfactant showed characteristics of the individual components, whereas the complex of NC 2067 and CD or CDgemini surfactant presented new

Influence of pulmonary surfactant on in vitro bactericidal activities of amoxicillin, ceftazidime, and tobramycin

NARCIS (Netherlands)

A. van 't Veen (Annemarie); J.W. Mouton (Johan); D.A.M.P.J. Gommers (Diederik); J.A.J.W. Kluytmans (Jan); P. Dekkers; B.F. Lachmann (Burkhard)

1995-01-01

textabstractThe influence of a natural pulmonary surfactant on antibiotic activity was investigated to assess the possible use of exogenous surfactant as a vehicle for antibiotic delivery to the lung. The influence of surfactant on the bactericidal activity of

Improved surfactants formulation for remediation of oil sludge recovery

International Nuclear Information System (INIS)

Syed Hakimi Sakuma Syed Ahmad; Shahidan Radiman

2000-01-01

Surfactant enhanced remediation based on mobilisation of the residual NAPLs (oil sludge) which is radioactive depends on the tendency of the surfactants to lower interfacial tension. Mobilisation has greater potential than solubilisation to increase the rate of remediation. Optimised surfactants formulation was determined with concentration of Aqua 2000 and D Bond of 1% wt respectively, sodium chloride concentration of 2 gmL -1 and addition of 3% wt butanol as cosolvent. The formulation was of benefit not only able to decrease further the interfacial tension of aqueous solution containing oil emulsion, but also to make possible to be more mobile and destruction of mixed liquid crystals that formed. Formation of liquid crystals can hinders significantly recovery efficiency of aqueous solution containing oil emulsion in field remediation work. In a 100 litres soil column experiment conducted containing oil emulsion in field sludge soil and using the surfactants formulation for flushing, miniemulsion formed sizes maintained at average size between 125 nm and 280 nm before and after remediation. Total oil and grease concentration removed from the soil were significant due to the decreased in oil emulsion sizes, increase mobility and solubility. (Author)

Surfactants non-monotonically modify the onset of Faraday waves

Science.gov (United States)

Strickland, Stephen; Shearer, Michael; Daniels, Karen

2017-11-01

When a water-filled container is vertically vibrated, subharmonic Faraday waves emerge once the driving from the vibrations exceeds viscous dissipation. In the presence of an insoluble surfactant, a viscous boundary layer forms at the contaminated surface to balance the Marangoni and Boussinesq stresses. For linear gravity-capillary waves in an undriven fluid, the surfactant-induced boundary layer increases the amount of viscous dissipation. In our analysis and experiments, we consider whether similar effects occur for nonlinear Faraday (gravity-capillary) waves. Assuming a finite-depth, infinite-breadth, low-viscosity fluid, we derive an analytic expression for the onset acceleration up to second order in ɛ =√{ 1 / Re } . This expression allows us to include fluid depth and driving frequency as parameters, in addition to the Marangoni and Boussinesq numbers. For millimetric fluid depths and driving frequencies of 30 to 120 Hz, our analysis recovers prior numerical results and agrees with our measurements of NBD-PC surfactant on DI water. In both case, the onset acceleration increases non-monotonically as a function of Marangoni and Boussinesq numbers. For shallower systems, our model predicts that surfactants could decrease the onset acceleration. DMS-0968258.

Vitamin K-dependent carboxylation of pulmonary surfactant-associated proteins

International Nuclear Information System (INIS)

Rannels, S.R.; Gallaher, K.J.; Wallin, R.; Rannels, D.E.

1987-01-01

Rat type II pneumocytes expressed vitamin K-dependent carboxylase activity that incorporated 14 CO 2 into microsomal protein precursors of molecular weights similar to those of surfactant-associated proteins (SAP). Compared to carboxylated precursor proteins present in the liver, these molecules appeared to be unique to the lung. Antibodies raised against purified rat surfactant reacted with SAP resolved by NaDodSO 4 /PAGE and with surfactant-containing lamellar bodies in type II pneumocyte cytoplasm. NaDodSO 4 /PAGE of microsomal proteins, after carboxylase-catalyzed incorporation of 14 CO 2 , demonstrated radiolabeled, immunoreactive products identical to SAP. The presence of γ-carboxyglutamic acid in these proteins was confirmed by HPLC analysis of SAP hydrolysates. Furthermore, lung carboxylase activity and SAP matured over similar time courses during fetal lung development. These results show that SAP are carboxylated by type II cells via a vitamin K-dependent pathway analogous to that for hepatic carboxylation of clotting factors. Further analogy to the clotting system suggest that γ-carboxyglutamic acid residues in SAP polypeptides play a role in Ca 2+ binding and thus in the known requirements for both cation and SAP in the physiological function of pulmonary surfactant

Clearance of 99mTc-DTPA and experimentally increased alveolar surfactant content

International Nuclear Information System (INIS)

Bos, J.A.H.; Wollmer, P.; Bakker, W.; Hannappel, E.; Lachmann, B.

1992-01-01

The authors measured clearance of 99m Tc-labeled diethylenetriamine pentaacetic acid ( 99m Tc-DTPA) in rabbits with experimentally increased alveolar surfactant content. In one group of animals, surfactant production was increased by treatment with ambroxol, and another group of animals was treated with tracheal instillation of natural surfactant. A group of untreated control animals and animals treated with instillation of saline were also studied. Clearance was measured during standard conditions of mechanical ventilation and during ventilation with large tidal volumes. In ambroxol- and surfactant-treated groups, clearance rate was reduced compared with untreated control animals. In contrast, clearance rate increased after saline instillation. The differences were observed at both modes of ventilation. The findings indicate that the pulmonary surfactant system is a rate-limiting factor for the clearance of 99m Tc-DTPA and that the volume dependence of clearance is not explained by stretching of the alveolar wall only. 28 refs., 2 figs., 1 tab

Experimental Study on the Properties and Displacement Effects of Polymer Surfactant Solution

Directory of Open Access Journals (Sweden)

Ke-Liang Wang

2013-01-01

Full Text Available Based on the characteristics of oil reservoirs and the requirements of further enhancing oil recovery at high water cut stage of Pubei Oilfield, the displacement performance of polymer surfactant is evaluated. Reasonable injection parameters and oil displacement effects after water flooding are also researched. Compared with conventional polymer with intermediate molecular weight, polymer surfactant has the properties of higher viscosity at low concentration condition and lower interfacial tension. Laboratory experiments indicate that the displacement effect of polymer surfactant is much better than that of conventional polymer at a slug size of 0.57 PV. The oil recovery of polymer surfactant increases by more than 10% after water flooding. Considering the actual situation of low-permeability of Pubei Oilfield reservoirs, the system viscosity of 30 mPa·s is chosen. The corresponding concentration of Type III polymer surfactant is 600 mg/L and the injected slug is 0.57 PV and the oil recovery can be increased by 11.69%.

Stable intermediates determine proteins' primary unfolding sites in the presence of surfactants

DEFF Research Database (Denmark)

Petersen, Steen Vang; Andersen, Kell kleiner; Enghild, Jan J.

2009-01-01

Despite detailed knowledge of the overall structural changes and stoichiometries of surfactant binding, little is known about which protein regions constitute the preferred sites of attack for initial unfolding. Here we have exposed three proteins to limited proteolysis at anionic (SDS) and catio......Despite detailed knowledge of the overall structural changes and stoichiometries of surfactant binding, little is known about which protein regions constitute the preferred sites of attack for initial unfolding. Here we have exposed three proteins to limited proteolysis at anionic (SDS......) and cationic (DTAC) surfactant concentrations corresponding to specific conformational transitions, using the surfactant-robust broad-specificity proteases Savinase and Alcalase. Cleavage sites are identified by SDS-PAGE and N-terminal sequencing. We observe well-defined cleavage fragments, which suggest......, cleavage sites can be rationalized from the structure of the protein's folding transition state and the position of loops in the native state. Nevertheless, they are more sensitive to choice of surfactant and protease, probably reflecting a heterogeneous and fluctuating ensemble of partially unfolded...

The benefits of paid employment among persons with common mental health problems: evidence for the selection and causation mechanism.

Science.gov (United States)

Schuring, Merel; Robroek, Suzan Jw; Burdorf, Alex

2017-11-01

Objectives The aims of this study were to (i) investigate the impact of paid employment on self-rated health, self-esteem, mastery, and happiness among previously unemployed persons with common mental health problems, and (ii) determine whether there are educational inequalities in these effects. Methods A quasi-experimental study was performed with a two-year follow-up period among unemployed persons with mental health problems. Eligible participants were identified at the social services departments of five cities in The Netherlands when being diagnosed with a common mental disorder, primarily depression and anxiety disorders, in the past 12 months by a physician (N=749). Employment status (defined as paid employment for ≥12 hours/week), mental health [Short Form 12 (SF-12)], physical health (SF-12), self-esteem, mastery, and happiness were measured at baseline, after 12 months and 24 months. The repeated-measurement longitudinal data were analyzed using a hybrid method, combining fixed and random effects. The regression coefficient was decomposed into between- and within-individual associations, respectively. Results The between-individuals associations showed that persons working ≥12 hours per week reported better mental health (b=26.7, SE 5.1), mastery (b=2.7, SE 0.6), self-esteem (b=5.7, SE 1.1), physical health (b=14.6, SE 5.6) and happiness (OR 7.7, 95% CI 2.3-26.4). The within-individual associations showed that entering paid employment for ≥12 hours per week resulted in better mental health (b=16.3, SE 3.4), mastery (b=1.7, SE 0.4), self-esteem (b=3.4, SE 0.7), physical health (b=9.8, SE 2.9), and happiness (OR 3.1, 95% CI 1.4-6.9). Among intermediate- and high-educated persons, entering paid employment had significantly larger effect on mental health than among low-educated persons. Conclusions This study provides evidence that entering paid employment has a positive impact on self-reported health; thus work should be considered as an important

Structure-activity relationship of surfactant for preparing DMFC anodic catalyst

International Nuclear Information System (INIS)

Su Yi; Xue Xinzhong; Xu Weilin; Liu Changpeng; Xing Wei; Zhou Xiaochun; Tian Tian; Lu Tianhong

2006-01-01

Three kinds of surfactants as stabilizer were applied to the preparation of electrocatalysts for direct methanol fuel cell (DMFC). The catalysts have been characterized by examining their catalytic activities, morphologies and particle sizes by means of cyclic voltammetry, chronoamperometry, X-ray diffraction and transmission electron microscopy (TEM). It is found that the surfactants with different structures have a significantly influence on the catalyst shape and activity. The catalysts prepared with non-ionic surfactants as the stabilizer show higher activity for direct oxidation of methanol. The structure-activity relationship (SAR) analysis has been explored and the effect of hydrophile-lipophile balance (HLB value) has also been discussed

Biosynthesis of Bio surfactant by Egyptian Local Bacterial Isolates Using Different Agricultural Wastes

International Nuclear Information System (INIS)

El-Shahawy, M.R.

2014-01-01

Fifteen bacterial isolates were isolated from sea water from the coast of the General Petroleum Company on Suez Gulf. They were screened for bio surfactant production using emulsification activity and haemolytic activity. The most potent isolate B11 were selected according to two parameters: The ability to grow and produce surfactant and its haemolytic activity on blood agar plates. The isolate B11 was characterized and identified as Bacillus licheniformis according to API system. The isolate was subjected to different doses of gamma irradiation in a trial to improve its ability for bio surfactant production which resulted in a passive effect on bio surfactant production. Three types of agricultural wastes (Rice straw, Cane Bagasse, Corn straw) were used as fertilizers for bio surfactant biosynthesis by the promising isolate in concentrations of 1, 2, 3, 4, 5 g/l. At five g/l concentration cane bagasse gave high production of bio surfactant with maximum capacity at (32%) flowed by rice straw at 18% and corn straw at 9.8 %.

Influence of MWCNT/surfactant dispersions on the mechanical properties of Portland cement pastes

Science.gov (United States)

Rodríguez, B.; Quintero, J. H.; Arias, Y. P.; Mendoza-Reales, O. A.; Ochoa-Botero, J. C.; Toledo-Filho, R. D.

2017-12-01

This work studies the reinforcing effect of Multi Walled Carbon Nanotubes (MWCNT) on cement pastes. A 0.35% solid concentration of MWCNT in powder was dispersed in deionized water with sodium dodecyl sulfate (cationic surfactant), cetylpyridinium chloride (anionic surfactant) and triton X-100 (amphoteric surfactant) using an ultrasonic tip processor. Three concentrations of each surfactant (1mM, 10mM and 100mM) were tested, and all samples were sonicated until an adequate dispersion degree was obtained. Cement pastes with additions of carbon nanotubes of 0.15% by mass of cement were produced in two steps; first the dispersions of MWCNT were combined with the mixing water using an ultrasonic tip processor to guarantee homogeneity, and then cement was added and mixed until a homogeneous paste was obtained. Direct tensile strength, apparent density and open porosity of the pastes were measured after 7 days of curing. It was found that the MWCNT/surfactants dispersions decrease the mechanical properties of the cement based matrix due to an increased porosity caused by the presence of surfactants.

Impacts of Residual Surfactant on Tetrachloroethene (PCE) Degradation Following Pilot-Scale SEAR Treatment at a Chloroethene-Impacted Site

Science.gov (United States)

Ramsburg, C. A.; Abriola, L. M.; Pennell, K. D.; Löffler, F. E.; Gamache, M.; Petrovskis, E. A.

2003-04-01

A pilot-scale surfactant-enhanced aquifer remediation (SEAR) demonstration was completed during the summer of 2000 at the Bachman Road site (Oscoda, MI USA). For this test, an aqueous solution of 60 g/L Tween 80 (polyoxyethylene (20) sorbitan monooleate) was used to recover tetrachloroethene (PCE) from a suspected source zone, located underneath a former dry-cleaning facility. Tween 80 was selected for use based upon its demonstrated capacity to solubilize PCE, “food-grade” status, and biodegradative potential. Hydraulic control was maintained throughout the test, with 95% of the injected surfactant mass recovered by a single extraction well. Source-zone monitoring conducted 15 months after SEAR treatment revealed the presence of previously undetected volatile fatty acids (acetate and formate) and PCE degradation products (trichloroethene, cis-1,2-dichloroethene, trans-1,2-dichlorethene, and vinyl chloride), in conjunction with PCE concentration reductions of approximately two orders-of-magnitude. The detection of volatile fatty acids is relevant, as they are likely fermentation products of residual Tween 80. Microbial reductive dechlorination is limited by available electron donors, and microcosm studies demonstrated that both acetate and formate support reductively dechlorinating populations present at the oligotrophic Bachman Road site aquifer. Surfactant transport simulations, using a regional flow model developed for the site, were employed to determine appropriate down-gradient monitoring locations. Drive point samples taken 15 months post-treatment in the vicinity of the simulated residual surfactant plume, contained elevated concentrations of acetate and PCE daughter products. Ongoing efforts include continued site-monitoring, and microcosm studies to corroborate a causal relationship between Tween 80 fermentation and PCE dechlorination.

Liquid crystalline states of surfactant solutions of isotropic micelles

International Nuclear Information System (INIS)

Bagdassarian, C.; Gelbart, W.M.; Ben-Shaul, A.

1988-01-01

We consider micellar solutions whose surfactant molecules prefer strongly to form small, globular aggregates in the absence of intermicellar interactions. At sufficiently high volume fraction of surfactant, the isotropic phase of essentially spherical micelles is shown to be unstable with respect to an orientationally ordered (nematic) state of rodlike aggregates. This behavior is relevant to the phase diagrams reported for important classes of aqueous amphiphilic solutions

Surfactant flushing remediation of o-dichlorobenzene and p-dichlorobenzene contaminated soil.

Science.gov (United States)

Pei, Guangpeng; Zhu, Yuen; Cai, Xiatong; Shi, Weiyu; Li, Hua

2017-10-01

Surfactant-enhanced remediation is used to treat dichlorobenzene (DCB) contaminated soil. In this study, soil column experiments were conducted to investigate the removal efficiencies of o-dichlorobenzene (o-DCB) and p-dichlorobenzene (p-DCB) from contaminated soil using micellar solutions of biosurfactants (saponin, alkyl polyglycoside) compare to a chemically synthetic surfactant (Tween 80). Leachate was collected and analyzed for o-DCB and p-DCB content. In addition, soil was analyzed to explore the effect of surfactants on soil enzyme activities. Results showed that the removal efficiency of o-DCB and p-DCB was highest for saponin followed by alkyl polyglycoside and Tween 80. The maximum o-DCB and p-DCB removal efficiencies of 76.34% and 80.43%, respectively, were achieved with 4 g L -1 saponin solution. However, an opposite result was observed in the cumulative mass of o-DCB and p-DCB in leachate. The cumulative extent of o-DCB and p-DCB removal by the biosurfactants saponin and alkyl polyglycoside was lower than that of the chemically synthetic surfactant Tween 80 in leachate. Soil was also analyzed to explore the effect of surfactants on soil enzyme activities. The results indicated that surfactants were potentially effective in facilitating soil enzyme activities. Thus, it was confirmed that the biosurfactants saponin and alkyl polyglycoside could be used for remediation of o-DCB and p-DCB contaminated soil. Copyright © 2017 Elsevier Ltd. All rights reserved.

Studies on interfacial tension and contact angle of synthesized surfactant and polymeric from castor oil for enhanced oil recovery

Science.gov (United States)

Babu, Keshak; Pal, Nilanjan; Bera, Achinta; Saxena, V. K.; Mandal, Ajay

2015-10-01

New synthesized polymeric surfactants have immensely attracted the researchers for further development of chemical enhanced oil recovery method particularly in surfactant flooding. Contact angle and interfacial tension measurement tests are the effective ways to identify proper chemicals/surfactants for enhanced oil recovery by chemical/surfactant flooding. In the present study a new polymeric surfactant was synthesized from pre-synthesized sodium methyl ester sulfonate (surfactant) and acrylamide for application in chemical enhanced oil recovery. The synthesized surfactant and polymeric surfactant were used to measure interfacial tension between their aqueous phase and crude oil phase to investigate the efficiency of the surfactants in reduction of interfacial tension. The synthesized polymeric surfactant has also ability to control the mobility because of its viscous nature in aqueous solution. Contact angles of solid-crude oil-surfactant interface were also measured to study the effect of the synthesized surfactant and polymeric surfactant on wettability alteration mechanism. Synergistic effect was studied by using NaCl and synthesized surfactants on interfacial tension. Dynamic interfacial tensions of the surfactant and polymeric surfactant solutions with crude oil were measured at different NaCl concentrations. Interfacial tension was found to be lowered up to 10-2 to 10-3 mN/m which is effective for oil recovery. Measurement of contact angle indicates the wettability change of the quartz surface. Comparative studies on efficiencies of synthesized sodium methyl ester sulfonate surfactant and polymeric surfactant were also carried out with respect to interfacial tension reduction and contact angle change.

Influence of clay and surfactant content in non-aqueous fluid rheology

International Nuclear Information System (INIS)

Guedes, I.C.; Gomes, N.L.; Menezes, R.R.; Campos, L.F.A.; Ferreira, H.S.

2012-01-01

The bentonite clay used as viscosity agent in the production of non-aqueous fluids cannot be used without organic treatment for their surfaces to become hydrophobic. These clays are called organophilic clays, and are generally obtained by adding, in an aqueous way, ionic or a nonionic surfactant. Recent studies of the variables involved in the dispersion of bentonite clays and in the process of organophilization, showed their lack of influence. This work aims to study the influence of clay content and surfactants on the rheology of nonaqueous fluids. To this end, the clays were treats and characterized, evidencing the incorporation of the surfactant, and then formulated non-aqueous fluids, following PETROBRAS standards, being possible to verify the influence of clay content and surfactant both from the point of view as the characterizing and rheological behavior. (author)

Mg-doped hydroxyapatite nanoplates for biomedical applications: A surfactant assisted microwave synthesis and spectroscopic investigations

International Nuclear Information System (INIS)

Mishra, Vijay Kumar; Bhattacharjee, Birendra Nath; Parkash, Om; Kumar, Devendra; Rai, Shyam Bahadur

2014-01-01

Highlights: • Microwave irradiation technique: employed for the synthesis of Mg-HAp nanoplates. • Surfactant (EDTA) assisted synthesis of Mg-HAp. • FT-IR and Raman analysis of functional groups of Mg-HAp. - Abstract: Nanoplates of Mg doped hydroxyapatite (Mg-HAp) were derived successfully and rapidly via microwave irradiation technique. Hydroxyapatite (HAp) is the hard tissues and main inorganic component in mammals. Different nanostructures of HAp exist in different parts of human bone but nanorods are very common due to its intrinsic nature to grow in rode-like structure under physiological as well as under applied ambient conditions in laboratory. On the addition of Mg at very low level (0.06 mol%) in pure HAp results the formation of 2-D plate-like nanostructures rather than rod-like which is the matter of interest. In this attempt our efforts have been focused on the study of effect of Mg incorporation on structural and spectroscopic properties of HAp prepared via microwave irradiation technique. This technique is preferred due to several advantages viz. very fast as well as homogeneous heating, time/energy saving and eco-friendliness. The calcium nitrate tetrahydrate (Ca(NO 3 ) 2 ⋅4H 2 O)) as a source of calcium, magnesium nitrate hexahydrate (Mg(NO 3 ) 2 ⋅6H 2 O) as a source of magnesium, disodium hydrogen phosphate dihydrate (NaH 2 PO 4 ⋅2H 2 O) as a source of phosphorous and sodium ethylene diamine tetra acetate (NaEDTA) as a surfactant were used as starting reagents. Sodium hydroxide (NaOH) pellets were employed to adjust the pH value of final solution. The solution of fixed pH value was kept into the microwave oven generating waves of frequency 2.45 GHz (water absorption frequency) and power 750 W for 8 min. The precipitate thus obtained was washed, centrifuged and then dried at 100 °C for 2 h. Dried powder was then calcined at 700 °C for 2 h. The bright white powder thus obtained was characterized structurally using X-ray diffraction and

Mg-doped hydroxyapatite nanoplates for biomedical applications: A surfactant assisted microwave synthesis and spectroscopic investigations

Energy Technology Data Exchange (ETDEWEB)

Mishra, Vijay Kumar [Department of Physics, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India); Bhattacharjee, Birendra Nath; Parkash, Om [Department of Ceramic Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005 (India); Kumar, Devendra, E-mail: devendra.cer@iitbhu.ac.in [Department of Ceramic Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005 (India); Rai, Shyam Bahadur, E-mail: sbrai49@yahoo.co.in [Department of Physics, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India)

2014-11-25

Highlights: • Microwave irradiation technique: employed for the synthesis of Mg-HAp nanoplates. • Surfactant (EDTA) assisted synthesis of Mg-HAp. • FT-IR and Raman analysis of functional groups of Mg-HAp. - Abstract: Nanoplates of Mg doped hydroxyapatite (Mg-HAp) were derived successfully and rapidly via microwave irradiation technique. Hydroxyapatite (HAp) is the hard tissues and main inorganic component in mammals. Different nanostructures of HAp exist in different parts of human bone but nanorods are very common due to its intrinsic nature to grow in rode-like structure under physiological as well as under applied ambient conditions in laboratory. On the addition of Mg at very low level (0.06 mol%) in pure HAp results the formation of 2-D plate-like nanostructures rather than rod-like which is the matter of interest. In this attempt our efforts have been focused on the study of effect of Mg incorporation on structural and spectroscopic properties of HAp prepared via microwave irradiation technique. This technique is preferred due to several advantages viz. very fast as well as homogeneous heating, time/energy saving and eco-friendliness. The calcium nitrate tetrahydrate (Ca(NO{sub 3}){sub 2}⋅4H{sub 2}O)) as a source of calcium, magnesium nitrate hexahydrate (Mg(NO{sub 3}){sub 2}⋅6H{sub 2}O) as a source of magnesium, disodium hydrogen phosphate dihydrate (NaH{sub 2}PO{sub 4}⋅2H{sub 2}O) as a source of phosphorous and sodium ethylene diamine tetra acetate (NaEDTA) as a surfactant were used as starting reagents. Sodium hydroxide (NaOH) pellets were employed to adjust the pH value of final solution. The solution of fixed pH value was kept into the microwave oven generating waves of frequency 2.45 GHz (water absorption frequency) and power 750 W for 8 min. The precipitate thus obtained was washed, centrifuged and then dried at 100 °C for 2 h. Dried powder was then calcined at 700 °C for 2 h. The bright white powder thus obtained was characterized

COUPLING THE ALKALINE-SURFACTANT-POLYMER TECHNOLOGY AND THE GELATION TECHNOLOGY TO MAXIMIZE OIL PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Malcolm Pitts; Jie Qui; Dan Wilson; Phil Dowling

2004-05-01

Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or more efficient areal sweep efficiency those with high permeability contrast ''thief zones''. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more oil than waterflooding in the swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to the naturally fractured reservoirs or those with thief zones because much of the injected solution bypasses the target pore space containing oil. The objective of this work is to investigate whether combining these two technologies could broaden the applicability of alkaline-surfactant-polymer flooding into these reservoirs. Fluid-fluid interaction with different gel chemical compositions and alkaline-surfactant-polymer solution with pH values ranging from 9.2 to 12.9 have been tested. Aluminum-polyacrylamide gels are not stable to alkaline-surfactant-polymer solutions at any pH. Chromium--polyacrylamide gels with polymer to chromium ion ratios of 25 or greater were stable to alkaline-surfactant-polymer solutions if solution pH was 10.6 or less. When the polymer to chromium ion was 15 or less, chromium-polyacrylamide gels were stable to alkaline-surfactant-polymer solutions with pH values up to 12.9. Chromium-xanthan gum gels were stable to alkaline-surfactant-polymer solutions with pH values of 12.9 at the polymer to chromium ion ratios tested. Silicate-polyacrylamide, resorcinol-formaldehyde, and sulfomethylated resorcinol-formaldehyde gels were also stable to alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Iron-polyacrylamide gels were immediately destroyed when contacted with any of the alkaline-surfactant-polymer solutions with pH values of 9.2 to 12.9.

Surface and micellar properties of Chloroquine Diphosphate and its interactions with surfactants and Human Serum Albumin

International Nuclear Information System (INIS)

Usman, Muhammad; Siddiq, Mohammad

2013-01-01

Highlights: ► Free energy of adsorption is more negative than free energy of micellization. ► Shifts in UV/Visible spectra in presence of SDS indicated interaction of CLQ with SDS. ► The decrease in fluorescence intensity of HSA by CLQ shows its binding with HSA. -- Abstract: This manuscript addresses the physicochemical behavior of an antimalarial drug Chloroquine Diphosphate (CLQ) as well as its interaction with anionic surfactants and Human Serum Albumin (HSA). Surface tension and specific conductivity were employed to detect the critical micelle concentration (CMC) and thus its surface and thermodynamic parameters were calculated. Solubilization of this drug within micelles of anionic surfactant sodium dodecyl sulfate (SDS) has also been studied. UV/Visible spectroscopy was used to calculate partition coefficient (K x ), free energy of partition and number of drug molecules per micelle. The complexation of drug with HSA at physiological conditions (pH 7.4) has also been analyzed by using UV/Visible and fluorescence spectroscopy. The values of drug-protein binding constant, number of binding sites and free energy of binding were calculated

Modification of Deeply Buried Hydrophobic Interfaces by Ionic Surfactants

Energy Technology Data Exchange (ETDEWEB)

L Tamam; D Pontoni Z Sapir; S Yefet; S Sloutskin; B Ocko; H Reichert; M Deutsch

2011-12-31

Hydrophobicity, the spontaneous segregation of oil and water, can be modified by surfactants. The way this modification occurs is studied at the oil-water interface for a range of alkanes and two ionic surfactants. A liquid interfacial monolayer, consisting of a mixture of alkane molecules and surfactant tails, is found. Upon cooling, it freezes at T{sub s}, well above the alkane's bulk freezing temperature, T{sub b}. The monolayer's phase diagram, derived by surface tensiometry, is accounted for by a mixtures-based theory. The monolayer's structure is measured by high-energy X-ray reflectivity above and below T{sub s}. A solid-solid transition in the frozen monolayer, occurring approximately 3 C below T{sub s}, is discovered and tentatively suggested to be a rotator-to-crystal transition.

Effect of surfactants on the spectrofluorimetric properties of zearalenone

International Nuclear Information System (INIS)

Appell, Michael; Bosma, Wayne B.

2011-01-01

The chemiluminescent properties of the estrogenic mycotoxin zearalenone in the presence of aqueous micellar media were investigated using steady state fluorescence techniques. Micelles of surfactants sodium dodecyl sulfate (SDS), hexadecyltrimethylammonium bromide (CTAB), and non-ionic Triton X-100 enhanced the fluorescence intensity of zearalenone in aqueous solutions. The binding constants have been determined and indicate zearalenone has the highest affinity for Triton X-100, followed by CTAB, and then by SDS. The encapsulation of zearalenone by the micelles studied is spontaneous and exothermic. The selective microenvironments provided by organized micellar systems offer an attractive medium to modulate fluorescence detection of zearalenone. - Highlights: → Surfactants can selectively modulate the fluorescence detection of zearalenone. → Binding studies provide information on the zearalenone-surfactant interactions. → Fluorescence intensity of zearalenone is related to the micelle microenvironment.

Surfactant mediated slurry formulations for Ge CMP applications

KAUST Repository

Basim, G. Bahar

2013-01-01

In this study, slurry formulations in the presence of self-assembled surfactant structures were investigated for Ge/SiO2 CMP applications in the absence and presence of oxidizers. Both anionic (sodium dodecyl sulfate-SDS) and cationic (cetyl trimethyl ammonium bromide-C12TAB) micelles were used in the slurry formulations as a function of pH and oxidizer concentration. CMP performances of Ge and SiO2 wafers were evaluated in terms of material removal rates, selectivity and surface quality. The material removal rate responses were also assessed through AFM wear rate tests to obtain a faster response for preliminary analyses. The surfactant adsorption characteristics were studied through surface wettability responses of the Ge and SiO2 wafers through contact angle measurements. It was observed that the self-assembled surfactant structures can help obtain selectivity on the silica/germanium system at low concentrations of the oxidizer in the slurry. © 2013 Materials Research Society.

Toxicity ranking and toxic mode of action evaluation of commonly used agricultural adjuvants on the basis of bacterial gene expression profiles.

Directory of Open Access Journals (Sweden)

Ingrid Nobels

Full Text Available The omnipresent group of pesticide adjuvants are often referred to as "inert" ingredients, a rather misleading term since consumers associate this term with "safe". The upcoming new EU regulation concerning the introduction of plant protection products on the market (EC1107/2009 includes for the first time the demand for information on the possible negative effects of not only the active ingredients but also the used adjuvants. This new regulation requires basic toxicological information that allows decisions on the use/ban or preference of use of available adjuvants. In this study we obtained toxicological relevant information through a multiple endpoint reporter assay for a broad selection of commonly used adjuvants including several solvents (e.g. isophorone and non-ionic surfactants (e.g. ethoxylated alcohols. The used assay allows the toxicity screening in a mechanistic way, with direct measurement of specific toxicological responses (e.g. oxidative stress, DNA damage, membrane damage and general cell lesions. The results show that the selected solvents are less toxic than the surfactants, suggesting that solvents may have a preference of use, but further research on more compounds is needed to confirm this observation. The gene expression profiles of the selected surfactants reveal that a phenol (ethoxylated tristyrylphenol and an organosilicone surfactant (ethoxylated trisiloxane show little or no inductions at EC(20 concentrations, making them preferred surfactants for use in different applications. The organosilicone surfactant shows little or no toxicity and good adjuvant properties. However, this study also illustrates possible genotoxicity (induction of the bacterial SOS response for several surfactants (POEA, AE, tri-EO, EO FA and EO NP and one solvent (gamma-butyrolactone. Although the number of compounds that were evaluated is rather limited (13, the results show that the used reporter assay is a promising tool to rank commonly

Evaluation of acute and chronic toxicity of DSS and LAS surfactants undergoing the irradiation with electron beam

International Nuclear Information System (INIS)

Romanelli, Maria Fernanda

2004-01-01

Surfactants are synthetic organic compounds widely used in cosmetic, food, textile, dyers and paper production industries and in particular detergents and others cleaning products industries. The world consumption is nearly 8 million tons per year. One of the main environmental issues coming from the use of these compounds is their toxicity that compromises the biological treatment of effluents and the quality of receiving waters. The objective of this work was the application of ionizing radiation by electron beam in the degradation and reduction of acute and chronic toxicities of surfactants sodium dodecylsulfate (SDS), dodecyl p-benzenesulfonate acid (LAS) and sodium dodecyl p-benzenesulfonate (LAS). This treatment technology has been studied as a pre-treatment for effluents containing toxic and non-biodegradable compounds, before the biological treatment. Two acute toxicity assays were employed, one with the micro-crustacean Daphnia similis and the other with the luminescent bacterium Vibrio fischeri along with a chronic toxicity assay with the micro-crustacean Ceriodaphnia dubia (just for SDS and acid LAS) for the non-irradiated and irradiated samples and radiation doses 3.0 kGy, 6.0 kGy, 9.0 kGy and 12.0 kGy. Physical-chemical parameters were evaluated for the following up the degradation of the surfactant molecules. The reductions of acute toxicity varied between 72.49% and 90.98% for SDS, 18.22% and 78.98% for acid LAS and 82.66% and 94.26% for sodium LAS. For the chronic toxicity, the reduction percentages varied between 64.03% and 83.01% for SDS and 47.48% and 64.91% for acid LAS. When one considers the application of the electron beam as a pre-treatment of effluents containing high concentrations of surfactants, the toxicity is an essential parameter allowing the further biological treatment of these effluents. (author)

Surfactant Sputtering: Theory of a new method of surface nanostructuring by ion beams

International Nuclear Information System (INIS)

Kree, R.; Yasseri, T.; Hartmann, A.K.

2009-01-01

We present a new Monte Carlo model and a new continuum theory of surface pattern formation due to 'surfactant sputtering', i.e. erosion by ion beam sputtering including a submonolayer coverage of additional, co-sputtered surfactant atoms. This setup, which has been realized in recent experiments in a controlled way leads to a number of interesting possibilities to modify pattern forming processing conditions. We will present three simple scenarios, which illustrate some potential applications of the method. In all three cases, simple Bradley-Harper type ripples appear in the absence of surfactant, whereas new, interesting structures emerge during surfactant sputtering.

Exogenous surfactant kinetics in infant respiratory distress syndrome : A novel method with stable isotopes

NARCIS (Netherlands)

Torresin, M; Zimmermann, LJI; Cogo, PE; Cavicchioli, P; Badon, T; Giordano, G; Zacchello, F; Sauer, PJJ; Carnielli, VP

Little is known about surfactant metabolism in newborn infants, since radioactive isotopes cannot be used in humans. We describe here a new method for studying exogenous surfactant pharmacokinetics in vivo. We measured surfactant half-life, pool size, and turnover time in eight preterm infants

Some aspects of surfactant action mechanism in the organic reagents - metal ions systems

International Nuclear Information System (INIS)

Chernova, R.K.; Shtykov, S.N.; Beloliptseva, G.M.; Sukhova, L.K.; Amelin, V.G.; Kulapina, E.G.

1984-01-01

Results are reviewed of investigations into the interaction of ions of Mo(6), W, Zr, Be, Sc, Nb, Ta, J, rare earths, a. o. with organic reagents of triphenylmethane class in the 8M H 2 SO 4 -pH14 acidity range and the 1x10 -3 -5x10 -6 M concentration range both in the presence and absence of different surfactant type (cetylpyridine, methyltrimethylammonium, synthanols, etc). Three types of effects, determining enhancement of the sensitivity and selectivity of reactions jn the Me-R-surfactant systems, were determined: an increase in the number of coordinated ligands, the activating effect of cation surfactants resulting in a potential complexing in acid media, multicenter interaction of polydentate ligands both via chelating groups and auxochrome groups in the presence of cation surfactants. Protolytic and flotation properties of ionic associates are considered. The observed effects are explained from the viewpoint of electrostatic and hydrophobic interactions in the R-surfactant systems, observed by the methods of NMR, polarography amperometry, conductometry. A possible use of the investigated M-R-surfactant systems as complexonometric indicators was evaluated. A possibility was shown of using them for direct titrimetric determination of hundredth milligram portions of Cu, Ga, In and Sc at a titrant concentratjon of less than 0.01 M. It follows from the estimation of basic optical parameters of the Me-R-surfactant systems that detection

Surfactant proteins gene variants in premature newborn infants with severe respiratory distress syndrome.

Science.gov (United States)

Somaschini, Marco; Presi, Silvia; Ferrari, Maurizio; Vergani, Barbara; Carrera, Paola

2017-12-19

Genetic surfactant dysfunction causes respiratory failure in term and near-term newborn infants, but little is known of such condition in prematures. We evaluated genetic surfactant dysfunction in premature newborn infants with severe RDS. A total of 68 preterm newborn infants with gestational age ≤32 weeks affected by unusually severe RDS were analysed for mutations in SFTPB, SFTPC and ABCA3. Therapies included oxygen supplementation, nasal CPAP, different modalities of ventilatory support, administration of exogenous surfactant, inhaled nitric oxide and steroids. Molecular analyses were performed on genomic DNA extracted from peripheral blood and Sanger sequencing of whole gene coding regions and intron junctions. In one case histology and electron microscopy on lung tissue was performed. Heterozygous previously described rare or novel variants in surfactant proteins genes ABCA3, SFTPB and SFTPC were identified in 24 newborn infants. In total, 11 infants died at age of 2 to 6 months. Ultrastructural analysis of lung tissue of one infant showed features suggesting ABCA3 dysfunction. Rare or novel genetic variants in genes encoding surfactant proteins were identified in a large proportion (35%) of premature newborn infants with particularly severe RDS. We speculate that interaction of developmental immaturity of surfactant production in association with abnormalities of surfactant metabolism of genetic origin may have a synergic worsening phenotypic effect.

Switching wormlike micelles of selenium-containing surfactant using redox reaction.

Science.gov (United States)

Zhang, Yongmin; Kong, Weiwei; Wang, Cheng; An, Pengyun; Fang, Yun; Feng, Yujun; Qin, Zhirong; Liu, Xuefeng

2015-10-14

A novel redox-switchable wormlike micellar system was developed based on a mixture of selenium-containing zwitterionic surfactant and commercially available anionic surfactant sodium dodecyl sulfate, which reversibly and quickly responds to H2O2 and vitamin C, and shows circulatory gel/sol transition, reflecting changes in aggregate morphology from entangled worms to vesicles.

Synthesis and characterization of zeolite material from coal ashes modified by surfactant

International Nuclear Information System (INIS)

Fungaro, D.A.; Borrely, S.I.

2010-01-01

Coal ash was used as starting material for zeolite synthesis by means of hydrothermal treatment. The surfactant-modified zeolite (SMZ) was prepared by adsorbing the cationic surfactant hexadecyltrimethylammonium bromide (HDTMA-Br) on the external surface of the zeolite from coal ash. The zeolite structure stability was monitored during the characterization of the materials by FTIR, XDR and SEM. The structural parameters of surfactant-modified zeolite are very close to that of corresponding non-modified zeolite which indicates that the crystalline nature of the zeolite remained intact after required chemical treatment with HDTMA-Br molecules and heating treatment for drying. The most intense peaks in the FTIR spectrum of HDTMA-Br were observed in SMZ spectrum confirming adsorption of surfactant on zeolites. (author)

Effect of Dialkyl Ammonium Cationic Surfactants on the Microfluidity of Membranes Containing Raft Domains.

Science.gov (United States)

Uyama, Makoto; Inoue, Kaori; Kinoshita, Koichi; Miyahara, Reiji; Yokoyama, Hirokazu; Nakano, Minoru

2018-01-01

It has been reported that a lot of receptors localize in lipid raft domains and that the microfluidity of these domains regulates the activation of these receptors. In this study, we focused on the lipid raft and in order to evaluate the physicochemical effects of surfactants on microfluidity of lipid membranes, we used liposomes comprising of egg-yolk L-α-phosphatidylcholine, egg-yolk sphingomyelin, and cholesterol as a model of cell membranes containing raft domains. The microfluidity of the domains was characterized by fluorescence spectrometry using 1,6-diphenyl-1,3,5-hexatriene and 2-dimethylamino-6-lauroylnaphthalene. Among several surfactants, dialkylammonium-type cationic surfactants most efficiently increased the microfluidity. It is therefore concluded that (1) the electrostatic interaction between the cationic surfactant and eggPC/eggSM/cholesterol liposome could be important, (2) surfactants with alkyl chains more effectively inserted into membranes than those with acyl chains, and (3) cationic surfactants with lower T m values have a greater ability to increase the fluidity.

Coupling surfactants with permanganate for DNAPL removal : coinjection or sequential application as delivery methods

Energy Technology Data Exchange (ETDEWEB)

Dugan, P.J. [Carus Corp., Peru, IL (United States); Siegrist, R.L. [Colorado School of Mines, Golden, CO (United States); Crimi, M.L. [Clarkson Univ., Potsdam, NY (United States)

2010-07-01

This PowerPoint presentation described a study conducted to test the effectiveness of surfactant-enhanced permanganate for the remediation of dense nonaqueous phase liquids (DNAPL). When DNAPL enters the environment, it can pollute millions of gallons of ground water and create huge dissolved plumes that act as long-term sources of contamination. Surfactants were used to enhance the solubilization and mobilization of DNAPL during the remediation process. In situ chemical oxidation (ISCO) was then used to deliver oxidants into the sub-surface to destroy organic contaminants in the soil and ground water. Experimental 2-D flow-through cell studies of 72 surfactants were conducted with the permanganate to evaluate delivery methods and determine compatible co-solvents for the surfactant process. Delivery methods included co-injection and sequential application. Four compatible surfactants were found to be compatible with the permanganate. A 90 percent DNAPL remediation rate was achieved using relatively low surfactant and oxidant concentrations. tabs., figs.

Mass spectrometry compatible surfactant for optimized in-gel protein digestion.

Science.gov (United States)

Saveliev, Sergei V; Woodroofe, Carolyn C; Sabat, Grzegorz; Adams, Christopher M; Klaubert, Dieter; Wood, Keith; Urh, Marjeta

2013-01-15

Identification of proteins resolved by SDS-PAGE depends on robust in-gel protein digestion and efficient peptide extraction, requirements that are often difficult to achieve. A lengthy and laborious procedure is an additional challenge of protein identification in gel. We show here that with the use of the mass spectrometry compatible surfactant sodium 3-((1-(furan-2-yl)undecyloxy)carbonylamino)propane-1-sulfonate, the challenges of in-gel protein digestion are effectively addressed. Peptide quantitation based on stable isotope labeling showed that the surfactant induced 1.5-2 fold increase in peptide recovery. Consequently, protein sequence coverage was increased by 20-30%, on average, and the number of identified proteins saw a substantial boost. The surfactant also accelerated the digestion process. Maximal in-gel digestion was achieved in as little as one hour, depending on incubation temperature, and peptides were readily recovered from gel eliminating the need for postdigestion extraction. This study shows that the surfactant provides an efficient means of improving protein identification in gel and streamlining the in-gel digestion procedure requiring no extra handling steps or special equipment.

Surfactant-enhanced alkaline flooding for light oil recovery. Final report

Energy Technology Data Exchange (ETDEWEB)

Wasan, D.T.

1996-05-01

In this report, we present the results of our experimental and theoretical studies in surfactant-enhanced alkaline flooding for light oil recovery. The overall objective of this work is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12. 0) for ultimate spontaneous emulsification and ultralow interfacial tension. In addition, we have (1) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, (2) investigated the mechanisms for spontaneous emulsification, (3) developed a technique to monitor low water content in oil and (4) developed a technique to study water-in-oil emulsion film properties, (5) investigated the effect of surfactant on the equilibrium and transient interfacial tension, (6) investigated the kinetics of oil removal from a silica surface, and (7) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, accounting for added surfactant. The results of the studies conducted during the course of this project are discussed.

Simultaneous determination of three surfactants and water in shampoo and liquid soap by ATR-FTIR.

Science.gov (United States)

Carolei, Luciano; Gutz, Ivano G R

2005-03-31

It is demonstrated for the first time that the principal constituents of a shampoo as well as of a liquid soap -three surfactants and water- can be determined directly, simultaneously and quickly in undiluted samples by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy in the middle infrared region, despite the broad absorption bands of the solvent. Two of the surfactants, sodium lauryl ether sulfate (SLES) and cocoamidopropyl betaine (CAPB), are common to both formulations; alkylpolyglucoside (APG) is the third surfactant of the liquid soap and cocodiethanolamide (CDEA), the corresponding ingredient of the shampoo. Absorbance data of the undiluted samples and of the calibration standards was collected in the middle infrared region of the spectrum (800-1600 and 1900-3000cm(-1)). Two methods of multivariate quantification were compared: classical least squares (CLS), where absorbance data measured at 200 wavenumbers was processed, and inverse least squares (ILS), where data at 10 selected wavenumbers was analyzed. A spectra normalization procedure, based on a dominating water band, was examined. Twenty-seven standard mixtures were used for each application, consisting of all combinations at three concentration levels of each surfactant, respectively the lower limit, the expected value and the upper limit accepted in quality control. By favoring wavenumbers where absorption bands of the minor components (APG in the liquid soap and CDEA in the shampoo) are more intense, good results were obtained for 18 simulated samples of shampoo and 18 samples of liquid soap, no matter if calculations were made by CLS or ILS. The relative errors for water (major component, 84-88%) and SLES (7-10%) were always below 2%; for CAPB (2-4%), APG (<2%) and CDEA (<2%), they occasionally reached 5% of the component, an uncertainty of less than 0.07% in terms of the sample weight.

REMEDIATION OF SOILS CONTAMINATED WITH MOTOR OIL BY HIGHLY BIODEGRADABLE SURFACTANTS

Directory of Open Access Journals (Sweden)

Ignacio Moya-Ramírez

2014-06-01

Full Text Available The remediation of a sandy soil contaminated with motor oil was studied by applying two different washing procedures: one discontinuous and the other continuous. In addition the capacity of three highly biodegradable surfactants, two synthetic (Glucopon 600 and Findet 1214N/23 and a biosurfactant from Bacillus subtilis, to enhance oil removal was tested. The results obtained with the continuous procedure were much better than those achieved with the discontinuous one, even in experiments conducted with distilled water. Both the addition of surfactants and the rise in temperature significantly increased the removal of the pollutant in experiments conducted with the discontinuous procedure, but the biosurfactant showed a higher capacity for soil remediation than the synthetic surfactants at concentrations close to its CMC. Conversely, when the continuous method was used, surfactant concentration seems to have a lower effect on motor oil removal, at least below the CMC.

Degradation of Surfactants in Hydroponic Wheat Root Zones

Science.gov (United States)

Monje, Oscar; McCoy, Lashelle; Flanagan, Aisling

Hygiene water recycling in recirculating hydroponic systems can be enhanced by plant roots by providing a substrate and root exudates for bacterial growth. However, reduced plant growth can occur during batch mode additions of high concentrations of surfactant. An analog hygiene water stream containing surfactants (Steol CS330, Mirataine CB) was added to a hydroponically-grown wheat plant root zone. The plants were grown at 700 mol mol-1 CO2, a photosynthetic photon flux of 300 mol m-2 s-1, and a planting density of 380 plants m-2. Volumetric oxygen mass transfer coefficients were determined using the fermentative/dynamic outgassing method to maintain adequate oxygen mass transfer rates in the root zone. This analysis suggested an optimal flow rate of the hydroponic solution of 5 L min-1. The hydroponic system was inoculated with biofilm from a bioreactor and rates of surfactant degradation were measured daily based on reduction in chemical oxygen demand (COD). The COD decreased from 400 to 100 mg L-1 after 2 days following batch addition of the analog hygiene water to the hydroponic system. Measurements of dissolved oxygen concentration and solution temperature suggest that the root zone was provided adequate aeration to meet both oxygen demands from plant and microbial respiration during the degradation of the surfactant. Results from this study show that hydroponic systems can be used to enhance rates of hygiene water processing.

Naturally occurring surfactants and their functional design. Seitai yurai safakutanto to kinoka sekkei

Energy Technology Data Exchange (ETDEWEB)

Ishigami, Y [National Inst. of Materials and Chemical Research, Tsukuba (Japan)

1994-04-20

An active use of the natural materials replaced the petroleum chemical products and an attempt for a development of the organism imitation materials are not limited only on the surfactants, but become a great trend also widely over the dyestuff, plastics material, food, cosmetics, agricultural chemicals and so forth. In addition, an institution of the recognition system for an 'eco-mark' is done, and a development of the environment conformity materials (eco-material) is advanced. In Japan since around 1950, a practical application and a research and development of new surfactants have been rapidly progressed making the derivatives originated in a petroleum chemistry as an axis. In this paper, including a viewpoint of the ecotechnology, a chemical structure and function of the surfactant being derived from the organisms, a molecule design and attempt for functional material making of the biomimetic surfactants are described. The author considers the biomimetic surfactants as one of the approaches to develop a new functional surfactant as the new raw materials, and is performing a development of the admixtures for improving a defect the soap has and so forth. 80 refs., 3 figs., 5 tabs.

Surfactant-aided size exclusion chromatography

NARCIS (Netherlands)

Horneman, D.A.; Wolbers, M.; Zomerdijk, M.; Ottens, M.; Keurentjes, J.T.F.; Wielen, van der L.A.M.

2004-01-01

The flexibility and selectivity of size exclusion chromatog. (SEC) for protein purifn. can be modified by adding non-ionic micelle-forming surfactants to the mobile phase. The micelles exclude proteins from a liq. phase similar to the exclusion effect of the polymer fibers of the size exclusion

Adsorption of sugar surfactants at the air/water interface.

Science.gov (United States)

Varga, Imre; Mészáros, Róbert; Stubenrauch, Cosima; Gilányi, Tibor

2012-08-01

The adsorption isotherms of n-decyl-β-D-glucoside (β-C(10)G(1)) as well as various n-alkyl-β-D-maltosides (β-C(n)G(2)) with n=8, 10, 12 and 14 were determined from surface tension measurements. Based on the analysis of the adsorption isotherms, the total free energy change of adsorption was determined and a novel method was proposed to determine the maximum adsorbed amount of surfactant. It can be concluded that the driving force for adsorption first increases with increasing adsorbed amount of the sugar surfactants and then levels off in a plateau. This peculiar behaviour is interpreted as formation of a thin liquid-like alkane film of overlapping alkyl chains at the air/water interface once a certain adsorbed amount is exceeded. The driving force of adsorption depends on the alkyl chain length only and is not affected by the type of the head group. The hydrophobic contribution to the standard free energy change of adsorption was compared with the values of sodium alkylsulfate and alkyltrimethylammonium bromide surfactants. This comparison reveals that the hydrophobic driving force of adsorption is the largest for the sodium alkylsulfates, whereas it is the same for the sugar surfactants and the alkyltrimethylammonium bromides. Copyright © 2012 Elsevier Inc. All rights reserved.

A PIV Study of Drop-interface Coalescence with Surfactants

Science.gov (United States)

Weheliye, Weheliye Hashi; Dong, Teng; Angeli, Panagiota

2017-11-01

In this work, the coalescence of a drop with an aqueous-organic interface was studied by Particle Image Velocimetry (PIV). The effect of surfactants on the drop surface evolution, the vorticity field and the kinetic energy distribution in the drop during coalescence were investigated. The coalescence took place in an acrylic rectangular box with 79% glycerol solution at the bottom and Exxsol D80 oil above. The glycerol solution drop was generated through a nozzle fixed at 2cm above the aqueous/oil interface and was seeded with Rhodamine particles. The whole process was captured by a high-speed camera. Different mass ratios of non-ionic surfactant Span80 to oil were studied. The increase of surfactant concentration promoted deformation of the interface before the rupture of the trapped oil film. At the early stages after film rupture, two counter-rotating vortices appeared at the bottom of the drop which then travelled to the upper part. The propagation rates, as well as the intensities of the vortices decreased at high surfactant concentrations. At early stages, the kinetic energy was mainly distributed near the bottom part of the droplet, while at later stages it was distributed near the upper part of the droplet. Programme Grant MEMPHIS, Chinese Scholarship Council (CSC).

Interactions of structurally modified surfactants with reservoir minerals: Calorimetric, spectroscopic and electrokinetic study

Energy Technology Data Exchange (ETDEWEB)

Somasundaran, P.; Sivakumar, A.; Xu, Q.

1991-03-01

The objective of this project is to elucidate mechanisms of adsorption of structurally modified surfactants on reservoir minerals and to develop a full understanding of the effect of the surfactant structure on the nature of the adsorbed layers at the molecular level. An additional aim is to study the adsorption of surfactant mixtures on simple well-characterized minerals and on complex minerals representing real conditions. The practical goal of these studies is the identification of the optimum surfactant structures and their combinations for micellar flooding. In this work, the experiments on adsorption were focussed on the position of sulfonate and methyl groups on the aromatic ring of alkyl xylene sulfonates. A multi-pronged approach consisting of calorimetry, electrokinetics, wettability and spectroscopy is planned to elucidate the adsorption mechanism of surfactants and their mixtures on minerals such as alumina and kaolinite. 32 refs., 15 figs., 7 tabs.

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

NARCIS (Netherlands)

Bos, M.A.; Vliet, T. van

2001-01-01

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.

Vacuolar ATPase regulates surfactant secretion in rat alveolar type II cells by modulating lamellar body calcium.

Directory of Open Access Journals (Sweden)

Narendranath Reddy Chintagari

2010-02-01

Full Text Available Lung surfactant reduces surface tension and maintains the stability of alveoli. How surfactant is released from alveolar epithelial type II cells is not fully understood. Vacuolar ATPase (V-ATPase is the enzyme responsible for pumping H(+ into lamellar bodies and is required for the processing of surfactant proteins and the packaging of surfactant lipids. However, its role in lung surfactant secretion is unknown. Proteomic analysis revealed that vacuolar ATPase (V-ATPase dominated the alveolar type II cell lipid raft proteome. Western blotting confirmed the association of V-ATPase a1 and B1/2 subunits with lipid rafts and their enrichment in lamellar bodies. The dissipation of lamellar body pH gradient by Bafilomycin A1 (Baf A1, an inhibitor of V-ATPase, increased surfactant secretion. Baf A1-stimulated secretion was blocked by the intracellular Ca(2+ chelator, BAPTA-AM, the protein kinase C (PKC inhibitor, staurosporine, and the Ca(2+/calmodulin-dependent protein kinase II (CaMKII, KN-62. Baf A1 induced Ca(2+ release from isolated lamellar bodies. Thapsigargin reduced the Baf A1-induced secretion, indicating cross-talk between lamellar body and endoplasmic reticulum Ca(2+ pools. Stimulation of type II cells with surfactant secretagogues dissipated the pH gradient across lamellar bodies and disassembled the V-ATPase complex, indicating the physiological relevance of the V-ATPase-mediated surfactant secretion. Finally, silencing of V-ATPase a1 and B2 subunits decreased stimulated surfactant secretion, indicating that these subunits were crucial for surfactant secretion. We conclude that V-ATPase regulates surfactant secretion via an increased Ca(2+ mobilization from lamellar bodies and endoplasmic reticulum, and the activation of PKC and CaMKII. Our finding revealed a previously unrealized role of V-ATPase in surfactant secretion.

Nanofiltration: ion exchange system for effective surfactant removal from water solutions

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I. Kowalska

2014-12-01

Full Text Available A system combining nanofiltration and ion exchange for highly effective separation of anionic surfactant from water solutions was proposed. The subjects of the study were nanofiltration polyethersulfone membranes and ion-exchange resins differing in type and structure. The quality of the treated solution was affected by numerous parameters, such as quality of the feed solution, membrane cut-off, resin type, dose and the solution contact time with the resin. A properly designed purification system made it possible to reduce the concentration of anionic surfactant below 1 mg L-1 from feed solutions containing surfactant in concentrations above the CMC value.

Derecruitment Test and Surfactant Therapy in Patients with Acute Lung Injury

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Alexey A. Smetkin

2012-01-01

Full Text Available Introduction. A recruitment maneuver (RM may improve gas exchange in acute lung injury (ALI. The aim of our study was to assess the predictive value of a derecruitment test in relation to RM and to evaluate the efficacy of RM combined with surfactant instillation in patients with ALI. Materials and Methods. Thirteen adult mechanically ventilated patients with ALI were enrolled into a prospective pilot study. The patients received protective ventilation and underwent RM followed by a derecruitment test. After a repeat RM, bovine surfactant (surfactant group, n=6 or vehicle only (conventional therapy group, n=7 was instilled endobronchially. We registered respiratory and hemodynamic parameters, including extravascular lung water index (EVLWI. Results. The derecruitment test decreased the oxygenation in 62% of the patients. We found no significant correlation between the responses to the RM and to the derecruitment tests. The baseline EVLWI correlated with changes in SpO2 following the derecruitment test. The surfactant did not affect gas exchange and lung mechanics but increased EVLWI at 24 and 32 hrs. Conclusions. Our study demonstrated no predictive value of the derecruitment test regarding the effects of RM. Surfactant instillation was not superior to conventional therapy and might even promote pulmonary edema in ALI.

BINDING OF IONIC SURFACTANTS ON OPPOSITELY CHARGED POLYELECTROLYTES OBSERVED BY FLUORESCENCE METHODS

Institute of Scientific and Technical Information of China (English)

Zhen Tong; Chao-yang Wang; Bi-ye Ren; Xin-xing Liu; Fang Zeng

2003-01-01

Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observed with fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB),dodecyltrimethylammonium chloride (DTAC), and nonionic surfactant octaethylene glycol monododecyl ether (C12E8) were allowed to bind on anionic poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and its pyrene and/or naphthalene labeled copolymers. The relative excimer emission intensity IE/IM of a cationic probe 1-pyrenemethylamine hydrochloride were chosen to monitor the binding process and the conformation change of surfactant-bound polyelectrolytes. The 1:1aggregation of polyelectrolyte-CTAB with respect to the charge was found as long as the CTAB concentration was slightly higher than its critical aggregation concentration (CAC). The intermolecular NRET indicated that the CTAB-bound polyelectrolytes aggregated together through the hydrophobic interaction between the CTAB tails. However, neither 1:1polyelectrolyte-DTAC aggregation nor intermolecular aggregation of DTAC-bound polyelectrolyte was observed owing to its weaker hydrophobicity of 12 carbon atoms in the tail, which is shorter than that of CTAB. As known from the fluorescence results, nonionic surfactant C12E8 did not bind on the anionic polyelectrolytes, but the presence of PAMPS promoted the micelle formation for C12E8 at the CAC slightly below its critical micelle concentration (CMC). The solid complex of dansyl labeled AMPS copolymer-surfactant exhibited a decrease in local polarity with increasing charge density of the polyelectrolyte or with alkane tail length of the surfactant. SAXS suggested a lamella structure for the AMPS copolymersurfactant solid complexes with a long period of 3.87 nm for CTAB and 3.04 nm for DTAC, respectively.

Modification of shape oscillations of an attached bubble by surfactants

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Tihon J.

2013-04-01

Full Text Available Surface-active agents (surfactants, e.g. washing agents strongly modifies properties of gas-liquid interface. We have carried out extensive experiments, in which we study effect of surfactants on the shape oscillations of a bubble, which is attached at a tip of a capillary. In the experiments, shape oscillations of a bubble are invoked by a motion of a capillary, to which the bubble is injected. Decaying oscillations are recorded and their frequency and damping are evaluated. By changing the excitation frequency, three lowest oscillation modes are studied. Experiments were repeated in aqueous solution of several surfactants (terpineol, SDS, CTAB, Triton X-100, Triton X-45 at various concentrations. Generally, these features are observed: Initially a surfactant addition leads to an increase of the oscillation frequency (though surface tension is decreasing; this effect can be attributed to the increasing interfacial elasticity. The decay time of oscillation is strongly decreasing, as a consequence of energy dissipation linked with Marangoni stresses. At a certain critical concentration, frequency decreases abruptly and the decay time passes by a minimum. With further addition of surfactant, frequency decreases, and the decay time slightly lengthens. Above critical micelle concentration, all these parameters stabilize. Interestingly, the critical concentration, at which frequency drop occurs, depends on mode order. This clearly shows that the frequency drop and minimum decay time are not a consequence of some abrupt change of interfacial properties, but are a consequence of some phenomena, which still need to be explained.

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

DEFF Research Database (Denmark)

Boutrup Stephansen, Karen; García-Díaz, María; Jessen, Flemming

2016-01-01

, and drug delivery. In the present study, we present a systematic investigation of how surfactants and proteins, as physiologically relevant components, interact with insulin-loaded fish sarcoplasmic protein (FSP) electrospun fibers (FSP-Ins fibers) in solution and thereby affect fiber properties...... such as accessible surface hydrophilicity, physical stability, and release characteristics of an encapsulated drug. Interactions between insulin-loaded protein fibers and five anionic surfactants (sodium taurocholate, sodium taurodeoxycholate, sodium glycocholate, sodium glycodeoxycholate, and sodium dodecyl sulfate......), a cationic surfactant (benzalkonium chloride), and a neutral surfactant (Triton X-100) were studied. The anionic surfactants increased the insulin release in a concentration-dependent manner, whereas the neutral surfactant had no significant effect on the release. Interestingly, only minute amounts...

Effects of Surfactants on the Rate of Chemical Reactions

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B. Samiey

2014-01-01

Full Text Available Surfactants are self-assembled compounds that depend on their structure and electric charge can interact as monomer or micelle with other compounds (substrates. These interactions which may catalyze or inhibit the reaction rates are studied with pseudophase, cooperativity, and stoichiometric (classical models. In this review, we discuss applying these models to study surfactant-substrate interactions and their effects on Diels-Alder, redox, photochemical, decomposition, enzymatic, isomerization, ligand exchange, radical, and nucleophilic reactions.

Use of surfactants to control island size and density

Science.gov (United States)

Merrell, Jason; Liu, Feng; Stringfellow, Gerald B.

2017-08-15

Methods of controlling island size and density on an OMVPE growth film may comprise adding a surfactant at a critical concentration level, allowing a growth phase for a first period of time, and ending the growth phase when desired island size and density are achieved. For example, the island size and density of an OMVPE grown InGaN thin film may be controlled by adding an antimony surfactant at a critical concentration level.

Micro-scale displacement of NAPL by surfactant and microemulsion in heterogeneous porous media

Science.gov (United States)

Javanbakht, Gina; Arshadi, Maziar; Qin, Tianzhu; Goual, Lamia

2017-07-01

Industrial processes such as remediation of oil-contaminated aquifers and enhanced oil recovery (EOR) often utilize chemical additives to increase the removal of non-aqueous phase liquids (NAPLs) from subsurface formations. Although the majority of crude oils are classified as LNAPLs, they often contain heavy molecules (DNAPLs) such as asphaltenes that tend to adsorb on minerals and alter their wettability. Effective additives are therefore those that can reduce the threshold capillary pressure, thus mobilizing LNAPL inside pore spaces and solubilizing DNAPL from rock surfaces. Nonionic surfactants in brine have often been injected to oil or contaminated aquifer formations in order to enhance NAPL displacement through IFT reduction. Recent studies revealed that surfactant-based microemulsions have a higher tendency to alter the wettability of surfaces, compared to surfactants alone, leading to more effective NAPL removal. However, the impact of these additives on pore-scale displacement mechanisms and multi-phase fluid occupancy in porous media is, to date, still unclear. In this study, x-ray microtomography experiments were performed to investigate the impact of surfactants and microemulsions on the mobilization and solubilization of NAPL in heterogeneous rocks. Saturation profiles indicated that an incremental NAPL removal was attained by addition of microemulsion to brine, compared with surfactant. Residual cluster size distributions revealed that microemulsions could break up large clusters into smaller disconnected ones, improving their mobilization in the rock. In-situ contact angle measurements showed that microemulsions could reverse the wettability of rough contaminated surfaces to a higher extent than surfactants. Unlike surfactant alone, the surfactant-solvent blend in the carrier fluid of microemulsions was able to penetrate rough grain surfaces, particularly those of dolomite cement, and desorb asphaltenes in the form of small-emulsified NAPL droplets