Extraction of ultrashort DNA molecules from herbarium specimens.

Science.gov (United States)

Gutaker, Rafal M; Reiter, Ella; Furtwängler, Anja; Schuenemann, Verena J; Burbano, Hernán A

2017-02-01

DNA extracted from herbarium specimens is highly fragmented; therefore, it is crucial to use extraction protocols that retrieve short DNA molecules. Improvements in extraction and DNA library preparation protocols for animal remains have allowed efficient retrieval of molecules shorter than 50 bp. Here, we applied these improvements to DNA extraction protocols for herbarium specimens and evaluated extraction performance by shotgun sequencing, which allows an accurate estimation of the distribution of DNA fragment lengths. Extraction with N-phenacylthiazolium bromide (PTB) buffer decreased median fragment length by 35% when compared with cetyl-trimethyl ammonium bromide (CTAB); modifying the binding conditions of DNA to silica allowed for an additional decrease of 10%. We did not observe a further decrease in length for single-stranded DNA (ssDNA) versus double-stranded DNA (dsDNA) library preparation methods. Our protocol enables the retrieval of ultrashort molecules from herbarium specimens, which will help to unlock the genetic information stored in herbaria.

Characterization of sodium bentonites: effect of treatment with ammonium salt- free organic surfactant; Caracterizacao de bentonitas sodicas: efeito do tratamento com surfactante organico livre de sal de amonio

Energy Technology Data Exchange (ETDEWEB)

Morita, R. Y.; Barbosa, R. V.; Kloss, J.R., E-mail: julianaweber@utfpr.edu.br [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Dartamento de Quimica e Biologia

2015-07-15

Bentonite, which the main clay mineral is montmorillonite, are commercially attractive because of its abundance in nature. The clays can be modified by ion exchange reactions of ions contained in the interlayer region with cationic surfactants that include ammonium or phosphonium salts. The clays origin and the type of surfactants (modifiers) are the main factors in the alteration of physical and chemical properties of these materials. This study aims to characterize and compare the results of natural bentonite commercially available and the effect of treatments with quaternary ammonium salt and an organic compound free of ammonium salt. The FTIR and XRD results indicate the process of organophilization of clays after treatment with the surfactants. These treatments have altered the average particle size, suggesting the formation of agglomerates, which was showed in the SEM images. The results of surface area and particle size data indicated the presence of larger particles. Although the two surfactants have shown similarities in the investigated properties, the organoclays free of ammonium salt are more promising in terms of its use as well as for their preparation and solubility. (author)

Performance of Cationic Surfactant Modified Sepiolite and Bentonite in Lead Sorption from Aqueous Solutions

Directory of Open Access Journals (Sweden)

H.R. Rafiei

2014-12-01

Full Text Available The remediation of soils and water contaminated with heavy metals generate a great need to develop efficient adsorbents for these pollutants. This study reports the sorption of lead (Pb by bentonite (Bent, and sepiolite (Sep, that were modified with cetyltrimethyl ammonium (CTMA+ organic cations. The natural and surfactant modified clays (organo-clays were characterized with some instrumental techniques including XRF, XRD, FTIR and SEM. Sorption studies were performed in a batch system, and the effects of various experimental parameters including contact time and initial Pb concentration were evaluated upon the Pb sorption onto sorbents. Maximum sorption of Pb was found to be, 83.26, 71.36, 56.25 and 37 mg g-1 for Sep, CTMA-Sep, Bent and CTMA-Bent adsorbents, respectively. The Pb sorption data were fitted to both the Langmuir and Freundlich models. The Freundlich model represented the sorption process better than the Langmuir model. Lead sorption rate was found to be considerably slower for organo-clays than that for unmodified clays. Sorption kinetics was evaluated by pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models. The sorption processes of organo-clays followed intraparticle diffusion kinetics. The results showed that the cationic surfactant modified bentonite and sepiolite sorbed less Pb than the unmodified clays.

Influence of branched quaternary ammonium surfactant molecules as levelers for copper electroplating from acidic sulfate bath

International Nuclear Information System (INIS)

Wang, An-yin; Chen, Biao; Fang, Lei; Yu, Jian-jun; Wang, Li-min

2013-01-01

A family of branched quaternary ammonium surfactants (compounds 1a–1c) with different carbon chains were synthesized for levelers applied in copper electroplating. Their inhibitory actions on copper electroplating were characterized by cyclic voltammetry (CV). Compound 1b, as representative structure type, was tested by means of different electrochemical methods including CV, polarization curve and electrochemical impedance spectroscopy (EIS) with different concentrations. The interaction between compound 1b and copper surface was investigated using atomic force microscope (AFM) and X-ray photoelectron spectra (XPS). The results indicated that our newly synthesized compounds, particular 1b, were effective levelers used for copper electroplating. Compound 1b could adsorb on copper surface to form an adsorption layer. The adsorption behavior of compound 1b on copper surface indicated that compound 1b could inhibit the copper electrodeposition, which provided favorable conditions used as a leveler. Moreover, the addition of compound 1b could increase the cathodic polarization, which was attributed to the adsorption of compound 1b during copper electroplating process. In addition, various surface morphologies and crystalline orientation of the plated copper films caused by different concentrations of compound 1b were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD) respectively. Effects of compound 1b on refining the grain size and changing the preferential orientation of the plated copper films were exhibited

Synthesis, characterization, and photocatalytic properties of Ni12P5 hollow microspheres

Science.gov (United States)

Liu, Shuling; Han, Xiaoli; Zhang, Hongzhe; Liu, Hui

2017-05-01

Ni12P5 hollow microspheres were prepared by a simple mixed cetyltrimethyl ammonium bromide/sodium dodecyl sulfate surfactant-assisted hydrothermal route. The as-prepared Ni12P5 microstructures were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). It was interesting to find that cetyltrimethyl ammonium bromide/sodium dodecyl sulfate could form a micro-reactor by the mixed micelles in the aqueous solution, which served as a soft template for Ni12P5 hollow microspheres with a diameter of 2 6 μm. Moreover, the as-prepared Ni12P5 hollow microspheres exhibited a good photocatalytic degradation activity for some organic dyes (such as Rhodamine B, Methylene Blue, Pyronine B, and Safranine T), and the degradation ratio could achieve more than 80%.

Significant effect of surfactant micelles on pH dependent fluorescent off-on-off behavior of Salicylaldehyde-2,4-Dinitrophenylhydrazone

Energy Technology Data Exchange (ETDEWEB)

Goswami, Priyanka [Department of Chemistry, Gauhati University, Guwahati 781 014 (India); Das, Diganta K., E-mail: digkdas@yahoo.co [Department of Chemistry, Gauhati University, Guwahati 781 014 (India)

2011-04-15

The fluorescence response to pH of 2,4 dinitrophenolhydrazone in 1:1 CH{sub 3}OH:H{sub 2}O and micellar mediums-negatively charged sodium dodecylsulphate (SDS), positively charged cetyltrimethyl ammonium bromide (CTAB) and neutral Triton X-100 (TX-100), is reported. At pH 4.0 the fluorescence of the molecule can be switched 'on' by selecting CTAB as the solvent. At pH 6.0 if the medium is TX-100 the fluorescence is 'off', but remains 'on' for the other three solvents. At pH 8.0, fluorescence is 'on' in the solvents except CTAB. SDS and TX-100 switch the fluorescence 'on' at pH 13.0 but for the other two solvents the fluorescence is 'off'. - Research highlights: The fluorescence response to pH of Salicylaldehyde-2,4 Dinitrophenolhydrazone in 1:1 CH{sub 3}OH:H{sub 2}O and in positively charged cetyltrimethyl ammonium bromide (CTAB) micellar medium shows 'off-on-off' behavior. In negatively charged sodium dodecylsulphate (SDS) the response of fluorescence of Salicylaldehyde-2,4 Dinitrophenolhydrazone to pH is 'off-on-on' type while in neutral Triton X-100 it is 'off-on-1/2on' type. At a given pH, fluorescence of 2,4 dinitrophenolhydrazone can be made 'on' or 'off' by selecting an appropriate pH.

Surfactant mediated hydrothermal synthesis, characterization and luminescent properties of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} core shell nanorods

Energy Technology Data Exchange (ETDEWEB)

Khajuria, Heena; Ladol, Jigmet; Khajuria, Sonika; Shah, Mohd Syed; Sheikh, H.N., E-mail: hnsheikh@rediffmail.com

2016-08-15

Highlights: • Core shell nanorods were synthesised by surfactant assisted hydrothermal method. • Morphology of core shell nanorods resembles those of core nanorods indicating coating of shell on cores. • More uniform and non-aggregated core shell nanorods were prepared in presence of surfactants. • Surfactant assisted prepared core shell nanorods show intense emission as compared to uncoated core nanorods. - Abstract: Core shell GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} nanorods were synthesized via hydrothermal route in the presence of different surfactants [cetyltrimethyl ammonium bromide (CTAB) and Sodium dodecyl sulphate (SDS)]. The nanorods were characterized by powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and photoluminescence (PL) studies. The X-ray diffraction results indicate good crystallinity and effective doping in core and core shell nanorods. SEM and TEM micrographs show that all of the as prepared gadolinium phosphate products have rod like shape. The compositional analysis of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} core was done by EDS. The emission intensity of the GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} core shell increased significantly with respect to those of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} core nanorods. The effect of surfactant on the uniformity, thickness and luminescence of the core shell nanorods was investigated.

A Spectroscopic and Electrochemical Investigation of Interactions of Anticancer Uracil Derivatives with Cationic and Anionic Surfactants

International Nuclear Information System (INIS)

Zafar, F.; Shah, A.; Ahmad, Z.; Siddiq, M.; Ali, S.; Asad Muhammad Khan, A. M.; Rana, U. A.

2015-01-01

Interactions of 5-fluorouracil (5-FU), a commercially available anti-cancer drug and two other possibly anti-cancer actives, 2-thiouracil (2-TU) and 2,4-dithiouracil (DTU), with anionic sodium dodecyl sulphate (SDS) and cationic cetlytrimethyl ammonium bromide (CTAB) surfactants were studied using cyclic voltammetry and UV-Visible spectroscopic techniques. The results from both techniques asserted the formation of complex between the drugs and surfactants. In the pre-micellar concentrations, the binding was mainly due to the interactions between the surfactants monomers (electrostatic) and the drug molecules, while in the post-micellar region, drug was encapsulated within the micelle due to electrostatic as well as hydrophobic interactions. The UV-Visible spectroscopic data of the interaction between 5-fluorouracil and the surfactants exhibited an isobestic point which indicated the presence of equilibrium species in bulk and the micellar phase. Binding constant, partition coefficient between bulk and miceller phase, and the number of drug molecules incorporated per micelle were calculated. (author)

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.

Kinetic and thermodynamic studies on the adsorption of anionic surfactant on quaternary ammonium cationic cellulose.

Science.gov (United States)

Zhang, Yuanzhang; Shi, Wenjian; Zhou, Hualan; Fu, Xing; Chen, Xuan

2010-06-01

Removal of anionic surfactants from aqueous solutions by adsorption onto quaternary ammonium cationic cellulose (QACC) was investigated. The effects of solution acidity, initial concentration, adsorption time, and temperature on the adsorption of sodium dodecyl-benzene sulfonate (SDBS), sodium lauryl sulfate (SLS), and sodium dodecyl sulfonate (SDS) were studied. The kinetic experimental data fit well with the pseudo-second-order model; the rate constant of the adsorption increased with temperature. The values of apparent activation energy for the adsorption were calculated as ranging from 10.2 to 17.4 kJ/ mol. The adsorption isotherm can be described by the Langmuir isotherm. The values of thermodynamic parameters (deltaH0, deltaS0, and deltaG0) for the adsorption indicated that this process was spontaneous and endothermic. At 318 K, the saturated adsorption capacities of QACC for SDBS, SLS, and SDS were 1.75, 1.53, and 1.39 mmol/g, respectively. The adsorption process was mainly chemisorption and partially physisorption. The results show that QACC is effective for the removal of anionic surfactants.

Determination of trace quaternary ammonium surfactants in water by combining solid-phase extraction with surface-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Chen, Y C; Sun, M C

2001-01-01

This study demonstrates the feasibility of combining solid-phase extraction (SPE) with surface-assisted laser desorption/ionization (SALDI) mass spectrometry to determine trace quaternary ammonium surfactants in water. The trace surfactants in water were directly concentrated on the surface of activated carbon sorbent in SPE. The activated carbon sorbent was then mixed with the SALDI liquid for SALDI analysis. No SPE elution procedure was necessary. Experimental results indicate that the surfactants with longer chain alkyl groups exhibit higher sensitivities than those with shorter chain alkyl groups in SPE-SALDI analysis. The detection limit for hexadecyltrimethylammonium bromide is around 10 ppt in SPE-SALDI analysis by sampling 100 mL of aqueous solution, while that of tetradecyltrimethylammonium bromide is about 100 ppt. The detection limit for decyltrimethylammonium bromide and dodecyltrimethylammonium bromide is in the low-ppb range. Copyright 2001 John Wiley & Sons, Ltd.

Cytotoxicity Effects of Different Surfactant Molecules Conjugated to Carbon Nanotubes on Human Astrocytoma Cells

Science.gov (United States)

Dong, Lifeng; Witkowski, Colette M.; Craig, Michael M.; Greenwade, Molly M.; Joseph, Katherine L.

2009-12-01

Phase contrast and epifluorescence microscopy were utilized to monitor morphological changes in human astrocytoma cells during a time-course exposure to single-walled carbon nanotube (SWCNT) conjugates with different surfactants and to investigate sub-cellular distribution of the nanotube conjugates, respectively. Experimental results demonstrate that cytotoxicity of the nanotube/surfactant conjugates is related to the toxicity of surfactant molecules attached on the nanotube surfaces. Both sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) are toxic to cells. Exposure to CNT/SDS conjugates (0.5 mg/mL) for less than 5 min caused changes in cell morphology resulting in a distinctly spherical shape compared to untreated cells. In contrast, sodium cholate (SC) and CNT/SC did not affect cell morphology, proliferation, or growth. These data indicate that SC is an environmentally friendly surfactant for the purification and dispersion of SWCNTs. Epifluorescence microscopy analysis of CNT/DNA conjugates revealed distribution in the cytoplasm of cells and did not show adverse effects on cell morphology, proliferation, or viability during a 72-h incubation. These observations suggest that the SWCNTs could be used as non-viral vectors for diagnostic and therapeutic molecules across the blood-brain barrier to the brain and the central nervous system.

The Effect Of Organic Surfactants On The Properties Of Common Hygroscopic Particles: Effective Densities, Reactivity And Water Evaporation Of Surfactant Coated Particles

Science.gov (United States)

Cuadrarodriguez, L.; Zelenyuk, A.; Imre, D.; Ellison, B.

2006-12-01

Measurements of atmospheric aerosol compositions routinely show that organic compounds account for a very large fraction of the particle mass. The organic compounds that make up this aerosol mass represent a wide range of molecules with a variety of properties. Many of the particles are composed of hygroscopic salts like sulfates, nitrates and sea-salt internally mixed with organics. While the properties of the hygroscopic salts are known, the effect of the organic compounds on the microphysical and chemical properties which include CCN activity is not clear. .One particularly interesting class of internally mixed particles is composed of aqueous salts solutions that are coated with organic surfactants which are molecules with long aliphatic chain and a water soluble end. Because these molecules tend to coat the particles' surfaces, a monolayer might be sufficient to drastically alter their hygroscopic properties, their CCN activity, and reactivity. The aliphatic chains, being exposed to the oxidizing atmosphere are expected to be transformed through heterogeneous chemistry, yielding complex products with mixed properties. We will report the results from a series of observations on ammonium sulfate, sodium chloride and sea salt particles coated with three types of surfactant molecules: sodium lauryl sulfate, sodium oleate and laurtrimonium chloride. We have been able to measure the effective densities of internally mixed particles with a range of surfactant concentration that start below a monolayer and extend all the way to particles composed of pure surfactant. For many of the measurements the data reveal a rather complex picture that cannot be simply interpreted in terms of the known pure-compound densities. For unsaturated hydrocarbons we observed and quantified the effect of oxidation by ozone on particle size, effective density and individual particle mass spectral signatures. One of the more important properties of these surfactants is that they can form a

Comparing effectiveness of rhamnolipid biosurfactant with a quaternary ammonium salt surfactant for hydrate anti-agglomeration.

Science.gov (United States)

York, J Dalton; Firoozabadi, Abbas

2008-01-24

Natural gas is projected to be the premium fuel of the 21st century because of availability, as well as economical and environmental considerations. Natural gas is coproduced with water from the subsurface forming gas hydrates. Hydrate formation may result in shutdown of onshore and offshore operations. Industry practice has been usage of alcohols--which have undesirable environmental impacts--to affect bulk-phase properties and inhibit hydrate formation. An alternative to alcohols is changing the surface properties through usage of polymers and surfactants, effective at 0.5-3 wt % of coproduced water. One group of low-dosage hydrate inhibitors (LDHI) are kinetic inhibitors, which affect nucleation rate and growth. A second group of LDHI are anti-agglomerants, which prevent agglomeration of small hydrate crystallites. Despite great potential, reported work on hydrate anti-agglomeration is very limited. In this paper, our focus is on the use of two vastly different surfactants as anti-agglomerants. We use a model oil, water, and tetrahydrofuran as a hydrate-forming species. We examine the effectiveness of a quaternary ammonium salt (i.e., quat). Visual observation measurements show that a small concentration of the quat (0.01%) can prevent agglomeration. However, a quat is not a green chemical and therefore may be undesirable. We show that a rhamnolipid biosurfactant can be effective to a concentration of 0.05 wt %. One difference between the two surfactants is the stability of the water-in-oil emulsions created. The biosurfactant forms a less stable emulsion, which makes it very desirable for hydrate application.

Investigation of electrokinetic and electrorheological properties of polyindole prepared in the presence of a surfactant

Energy Technology Data Exchange (ETDEWEB)

Unal, H. Ibrahim, E-mail: hiunal@gazi.edu.tr [Gazi University, Chemistry Department, Smart Materials Research Lab., Ankara (Turkey); Sahan, Bekir; Erol, Ozlem [Gazi University, Chemistry Department, Smart Materials Research Lab., Ankara (Turkey)

2012-05-15

Highlights: Black-Right-Pointing-Pointer Aggregated morphology was determined for PIN, spherical and porous hollows and everniae form morphologies were recorded for SPIN. Black-Right-Pointing-Pointer The PIN/SO and SPIN/SO systems showed almost similar electrokinetic attitudes and a typical shear thinning non-Newtonian viscoelastic behavior, vibration damping capability at elevated frequencies, and enhanced storage moduli with increasing temperature. Black-Right-Pointing-Pointer Non-linear recoverable viscoelastic manner was revealed from the creep-recovery experiments under external electric field. - Abstract: In this study, synthesis of polyindole (PIN) was carried out without and with the presence of a sodium dodecyl sulfate (SDS) surfactant (SPIN), using FeCl{sub 3} as an oxidizing agent. The synthesized materials were subjected to various characterizations techniques namely: particle size, magnetic susceptibility, elemental analysis, density, conductivity, dielectric constant, FTIR, {sup 1}H NMR, TGA, XRD, and SEM. Characterization results revealed the successful preparation of the homopolymers of PIN and SPIN. Zeta ({zeta})-potentials of the samples were measured in aqueous and non-aqueous (silicone oil, SO) media. Electrokinetic properties of PIN and SPIN in aqueous media were determined by {zeta}-potential measurements in the presence of various electrolytes (NaCl, BaCl{sub 2}, AlCl{sub 3}, Na{sub 2}SO{sub 4}) and surfactants (cetyltrimethyl ammonium bromide, SDS, and Triton X-100). Besides, the effect of pH onto {zeta}-potentials of the materials was also examined. The suspensions prepared in SO were subjected to external electric field strength and their electrorheological (ER) properties were investigated. Then the effects of shear rate, frequency, and temperature onto ER activities of the suspensions were examined. Further, creep and creep-recovery tests were applied to the PIN/SO and SPIN/SO suspension systems and reversible non-linear viscoelastic

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

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.

Synthesis and characterization of silica mesoporous material produced by hydrothermal continues pH adjusting path way

Directory of Open Access Journals (Sweden)

A. Salemi Golezani

2016-08-01

Full Text Available Mesoporous silica molecular sieves MCM-41 were synthesized under hydrothermal conditions. For this purpose, a solution with a molar coefficient of water, cetyltri-methyl ammonium bromide surfactants as template and sodium silicate as the source of SiO2 are used. Phase formation, morphology and gas absorption properties were investigated by XRD and BET analysis, respectively. The results showed that silica mesoporous material has been successfully synthesized. A favorable special surface and porosity volume together with regular arrangement of nano metric-hexagonal porosities were obtained from this synthesis. Thickness of the wall and average diameter of the pores are 0.8 nm and 4 nm, respectively.

A study of mesoporous silica-encapsulated gold nanorods as enhanced light scattering probes for cancer cell imaging

Energy Technology Data Exchange (ETDEWEB)

Zhan Qiuqiang; Qian Jun; Li Xin; He Sailing, E-mail: qianjun@coer.zju.edu.cn [Centre for Optical and Electromagnetic Research, State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310058 (China)

2010-02-05

Mesoporous encapsulation of gold nanorods (GNRs) in a silica shell of controllable thickness (4.5-25.5 nm) was realized through a single-step coating method without any intermediary coating. The dependence of localized surface plasmon resonance (LSPR) extinction spectra of the coated GNRs on the thickness of the silica shell was investigated with both simulation and experiments, which agreed well with each other. It was found that cetyltrimethyl ammonium bromide (CTAB) molecules, which act as surfactants for the GNRs and dissociate in the solution, greatly affect the silica coating. Mesoporous silica-encapsulated GNRs were also shown to be highly biocompatible and stable in bio-environments. Based on LSPR enhanced scattering, mesoporous silica-encapsulated GNRs were utilized for dark field scattering imaging of cancer cells. Biomolecule-conjugated mesoporous silica-encapsulated GNRs were specifically taken up by cancer cells in vitro, justifying their use as effective optical probes for early cancer diagnosis. Mesoporous silica can also be modified with functional groups and conjugated with certain biomolecules for specific labeling on mammalian cells as well as carrying drugs or biomolecules into biological cells.

Layered Zinc Hydroxide Salts Intercalated with Anionic Surfactants and Adsolubilized with UV Absorbing Organic Molecules

OpenAIRE

Cursino,Ana C. T.; Rives,Vicente; Carlos,Luís D.; Rocha,João; Wypych,Fernando

2015-01-01

Two anionic surfactants, dodecylsulfate (DDS) and dodecylbenzenesulfonate (DBS), were intercalated into layered zinc hydroxide salts (LHS) using the direct alkaline co-precipitation method, and characterized by powder X-ray diffraction (PXRD), Fourier-transform infrared (FTIR) and thermogravimetric analysis/differential thermal analysis (TGA/DTA). Different UV-absorbing organic molecules, like salicylates, cinnamates and benzophenones, were adsolubilized in the LHS interlayer following two di...

Mixed micelles of polyethylene glycol (23) lauryl ether with ionic surfactants studied by proton 1D and 2D NMR.

Science.gov (United States)

Gao, Hong-Chang; Zhao, Sui; Mao, Shi-Zhen; Yuan, Han-Zhen; Yu, Jia-Yong; Shen, Lian-Fang; Du, You-Ru

2002-05-01

(1)H NMR chemical shift, spin-lattice relaxation time, spin-spin relaxation time, self-diffusion coefficient, and two-dimensional nuclear Overhauser enhancement (2D NOESY) measurements have been used to study the nonionic-ionic surfactant mixed micelles. Cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) were used as the ionic surfactants and polyethylene glycol (23) lauryl ether (Brij-35) as the nonionic surfactant. The two systems are both with varying molar ratios of CTAB/Brij-35 (C/B) and SDS/Brij-35 (S/B) ranging from 0.5 to 2, respectively, at a constant concentration of 6 mM for Brij-35 in aqueous solutions. Results give information about the relative arrangement of the surfactant molecules in the mixed micelles. In the former system, the trimethyl groups attached to the polar heads of the CTAB molecules are located between the first oxy-ethylene groups next to the hydrophobic chains of Brij-35 molecules. These oxy-ethylene groups gradually move outward from the hydrophobic core of the mixed micelle with an increase in C/B in the mixed solution. In contrast to the case of the CTAB/Triton X-100 system, the long flexible hydrophilic poly oxy-ethylene chains, which are in the exterior part of the mixed micelles, remain coiled, but looser, surrounding the hydrophobic core. There is almost no variation in conformation of the hydrophilic chains of Brij-35 molecules in the mixed micelles of the SDS/Brij-35 system as the S/B increases. The hydrophobic chains of both CTAB and SDS are co-aggregated with Brij-35, respectively, in their mixed micellar cores.

Synthesis and optimization of cholesterol-based diquaternary ammonium Gemini Surfactant (Chol-GS) as a new gene delivery vector.

Science.gov (United States)

Kim, Bieong-Kil; Doh, Kyung-Oh; Bae, Yun-Ui; Seu, Young-Bae

2011-01-01

Amongst a number of potential nonviral vectors, cationic liposomes have been actively researched, with both gemini surfactants and bola amphiphiles reported as being in possession of good structures in terms of cell viability and in vitro transfection. In this study, a cholesterol-based diquaternary ammonium gemini surfactant (Chol-GS) was synthesized and assessed as a novel nonviral gene vector. Chol-GS was synthesized from cholesterol by way of four reaction steps. The optimal efficiency was found to be at a weight ratio of 1:4 of lipid:DOPE (1,2-dioleoyl-L-alpha- glycero-3-phosphatidylethanolamine), and at a ratio of between 10:1~15:1 of liposome:DNA. The transfection efficiency was compared with commercial liposomes and with Lipofectamine, 1,2-dimyristyloxypropyl-3-dimethylhydroxyethylammonium bromide (DMRIE-C), and N-[1-(2,3-dioleoyloxy)propyl]- N,N,N-trimethylammonium chloride (DOTAP). The results indicate that the efficiency of Chol-GS is greater than that of all the tested commercial liposomes in COS7 and Huh7 cells, and higher than DOTAP and Lipofectamine in A549 cells. Confirmation of these findings was observed through the use of green fluorescent protein expression. Chol-GS exhibited a moderate level of cytotoxicity, at optimum concentrations for efficient transfection, indicating cell viability. Hence, the newly synthesized Chol-GS liposome has the potential of being an excellent nonviral vector for gene delivery.

Impact of model perfume molecules on the self-assembly of anionic surfactant sodium dodecyl 6-benzene sulfonate.

Science.gov (United States)

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

2013-03-12

The impact of two model perfumes with differing degrees of hydrophobicity/hydrophilicity, linalool (LL) and phenylethanol (PE), on the solution structure of anionic surfactant sodium dodecyl 6-benzene sulfonate, LAS-6, has been studied by small angle neutron scattering, SANS. For both types of perfume molecules, complex phase behavior is observed. The phase behavior depends upon the concentration, surfactant/perfume composition, and type of perfume. The more hydrophilic perfume PE promotes the formation of more highly curved structures. At relatively low surfactant concentrations, small globular micelles, L1, are formed. These become perfume droplets, L(sm), stabilized by the surfactant at much higher perfume solution compositions. At higher surfactant concentrations, the tendency of LAS-6 to form more planar structures is evident. The more hydrophobic linalool promotes the formation of more planar structures. Combined with the greater tendency of LAS-6 to form planar structures, this results in the planar structures dominating the phase behavior for the LAS-6/linalool mixtures. For the LAS-6/linalool mixture, the self-assembly is in the form of micelles only at the lowest surfactant and perfume concentrations. Over most of the concentration-composition space explored, the structures are predominantly lamellar, L(α), or vesicle, L(v), or in the form of a lamellar/micellar coexistence. At low and intermediate amounts of LL, a significantly different structure is observed, and the aggregates are in the form of small, relatively monodisperse vesicles (i.e., nanovesicles), L(sv).

Adsorption of quantum dots onto polymer and Gemini surfactant films: a quartz crystal microbalance study.

Science.gov (United States)

Alejo, T; Merchán, M D; Velázquez, M M

2014-08-26

We used quartz crystal microbalance with dissipation to study the mechanical properties, the kinetics of adsorption, and the amount of CdSe quantum dots (QDs) adsorbed onto a SiO2 sensor, referred as bare sensor, onto the sensor modified with a film of the polymer poly(maleic anhydride-alt-1-octadecene), PMAO, or with a film of the Gemini surfactant ethyl-bis(dimethyl octadecyl ammonium bromide), abbreviated as 18-2-18. Results showed that when the sensor is coated with polymer or surfactant molecules, the coverage increases compared with that obtained for the bare sensor. On the other hand, rheological properties and kinetics of adsorption of QDs are driven by QD nanoparticles. Thus, the QD films present elastic behavior, and the elasticity values are independent of the molecule used as coating and similar to the elasticity value obtained for QDs films on the bare sensor. The QD adsorption is a two-step mechanism in which the fastest process is attributed to the QD adsorption onto the solid substrate and the slowest one is ascribed to rearrangement movements of the nanoparticles adsorbed at the surface.

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.

Effect of fluid velocity, temperature, and concentration of non-ionic surfactants on drag reduction

International Nuclear Information System (INIS)

Cho, Sung-Hwan; Tae, Choon-Seob; Zaheeruddin, M.

2007-01-01

The drag reduction (DR) and heat transfer efficiency reduction (ER) of non-ionic surfactant as a function of fluid velocity, temperature, and surfactant concentration were investigated. Several types of new surfactants, which contain amine-oxide and betaine, were developed. An experimental apparatus consisting of two temperature controlled water storage tanks, pumps, test specimen pipe and the piping network, two flow meters, two pressure gauges, a heat exchanger, and data logging system was built. From the experimental results, it was concluded that existing alkyl ammonium surfactant (CTAC; cethyl trimethyl ammonium chloride) had DR of 0.6-0.8 at 1000-2000 ppm concentration with fluid temperature ranging between 50 and 60 o C. However, the DR was very low when the fluid temperature was 70-80 o C. The new amine oxide and betaine surfactant (SAOB; stearyl amine oxide + betaine) had lower DR at fluid temperatures ranging between 50 and 60 o C compared with CTAC. However, with fluid temperature ranging between 70 and 80 o C the DR was 0.6-0.8 when the concentration level was between 1000 and 2000 ppm

Hydrothermal Synthesis of Nanoclusters of ZnS Comprised on Nanowires

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Magnus Willander

2013-09-01

Full Text Available Cetyltrimethyl ammonium bromide cationic (CTAB surfactant was used as template for the synthesis of nanoclusters of ZnS composed of nanowires, by hydrothermal method. The structural and morphological studies were performed by using X-ray diffraction (XRD, scanning electron microscopy (SEM and high resolution transmission electron microscopy (HRTEM techniques. The synthesized ZnS nanoclusters are composed of nanowires and high yield on the substrate was observed. The ZnS nanocrystalline consists of hexagonal phase and polycrystalline in nature. The chemical composition of ZnS nanoclusters composed of nanowires was studied by X-ray photo electron microscopy (XPS. This investigation has shown that the ZnS nanoclusters are composed of Zn and S atoms.

Hydrothermal Synthesis of Nanoclusters of ZnS Comprised on Nanowires.

Science.gov (United States)

Ibupoto, Zafar Hussain; Khun, Kimleang; Liu, Xianjie; Willander, Magnus

2013-09-09

Cetyltrimethyl ammonium bromide cationic (CTAB) surfactant was used as template for the synthesis of nanoclusters of ZnS composed of nanowires, by hydrothermal method. The structural and morphological studies were performed by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) techniques. The synthesized ZnS nanoclusters are composed of nanowires and high yield on the substrate was observed. The ZnS nanocrystalline consists of hexagonal phase and polycrystalline in nature. The chemical composition of ZnS nanoclusters composed of nanowires was studied by X-ray photo electron microscopy (XPS). This investigation has shown that the ZnS nanoclusters are composed of Zn and S atoms.

Studies on the role of unsaturation in the fatty acid surfactant molecule on the thermal conductivity of magnetite nanofluids.

Science.gov (United States)

Lenin, Ramanujam; Joy, Pattayil Alias

2017-11-15

To study the role of unsaturation in the surfactant molecule on the thermal conductivity of magnetite nanofluids, four different fatty acid (stearic, oleic, linoleic, and linolenic acids with different degree of unsaturation) coated magnetite nanoparticles of comparable size are prepared and dispersed in toluene. It is found that the nanofluid with the saturated fatty acid coated nanoparticles show larger viscosity than the fluid with the unsaturated fatty acid coated particles at all concentrations. Thermal conductivity studies show enhancement only above a critical concentration for all fluids. The critical concentration for thermal conductivity enhancement varies with the surfactant, possibly due to the difference in the degree of aggregation of the nanoparticles in the fluid, because of the difference in the conformation of the surfactant molecules on the nanoparticle's surface. The experimental thermal conductivity follows the Maxwell model at higher concentrations. From the overall studies, it is observed that the thermal conductivity of the fluids with aggregated or assembled nanoparticles shows slightly larger enhancement than that of the fluids with isolated particles. However, in the presence of a magnetic field, the fluids with isolated nanoparticles showed relatively larger enhancement, possibly due to the easy response of the isolated magnetite nanoparticles to the applied field. Copyright © 2017 Elsevier Inc. All rights reserved.

Solubilisation of a host molecule in a surfactant film: thermodynamic and structural approach in the case of lindane

International Nuclear Information System (INIS)

Testard, Fabienne

1996-01-01

In this research thesis, the author aimed at understanding the main aspects of solubilisation in the specific case of a pesticide, the lindane, which is a hydrophobic molecule, poorly soluble in water. She first proposes a review of some existing models of solubilisation, and presents the only existing predictive model for the prediction of solubilisation in water-ionic surfactant binary systems. She addresses these systems and tries to characterise disruptions induced by the presence of the solute for lindane-saturated solutions (study of phase diagrams, of structure for different surfactant concentrations and different temperatures). Then she focuses on a part of the ternary diagram which allows micro emulsions to be reached at the point of spontaneous null curvature. She reports the study (by neutron and X ray scattering at small angles) of structural information on the surfactant film in different aggregates of ternary solutions in presence of solute. She finally proposes a more chemical approach to solubilisation [fr

Preparation of Polyacrylonitrile-Kapok Hollow Microtubes Decorated with Cu Nanoparticles

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Agcaoili Apollo

2015-01-01

Full Text Available A novel copper (Cu nanoparticle carrier was fabricated using kapok natural microtubes as a substrate. Cu nanoparticles were grown on a thin polymer film on the surface of the kapok fibers. The polymer film was deposited on the surface of the microtube using a surfactant-assisted polymerization of acrylonitrile monomers. Cetyltrimethyl ammonium bromide (CTAB was used surfactant. The contact angle decreased from 120.5 to 0 after polyacrylonitrile coating (PAN, which suggests improved hydrophilicity of the kapok fibers. Addition of 1.5 mL acrylonitrile and 0.020 – 0.035 g CTAB yielded evenly coated kapok fibers. Cu nanoparticles, with diameters of 82-186 nm, were formed on the surface of the composite by reducing 0.16 M copper sulphate (CuSO4 with hydrazine (N2H4 at 70°C. EDX reveals that more Cu nanoparticles formed on the surface of PAN-kapok composites with 0.035g CTAB due to thicker PAN coating.

Precursor Mediated Synthesis of Nanostructured Silicas: From Precursor-Surfactant Ion Pairs to Structured Materials.

Science.gov (United States)

Hesemann, Peter; Nguyen, Thy Phung; Hankari, Samir El

2014-04-11

The synthesis of nanostructured anionic-surfactant-templated mesoporous silica (AMS) recently appeared as a new strategy for the formation of nanostructured silica based materials. This method is based on the use of anionic surfactants together with a co-structure-directing agent (CSDA), mostly a silylated ammonium precursor. The presence of this CSDA is necessary in order to create ionic interactions between template and silica forming phases and to ensure sufficient affinity between the two phases. This synthetic strategy was for the first time applied in view of the synthesis of surface functionalized silica bearing ammonium groups and was then extended on the formation of materials functionalized with anionic carboxylate and bifunctional amine-carboxylate groups. In the field of silica hybrid materials, the "anionic templating" strategy has recently been applied for the synthesis of silica hybrid materials from cationic precursors. Starting from di- or oligosilylated imidazolium and ammonium precursors, only template directed hydrolysis-polycondensation reactions involving complementary anionic surfactants allowed accessing structured ionosilica hybrid materials. The mechanistic particularity of this approach resides in the formation of precursor-surfactant ion pairs in the hydrolysis-polycondensation mixture. This review gives a systematic overview over the various types of materials accessed from this cooperative ionic templating approach and highlights the high potential of this original strategy for the formation of nanostructured silica based materials which appears as a complementary strategy to conventional soft templating approaches.

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.

Determination of quaternary ammonium compounds by potentiometric titration with an ionic surfactant electrode: single-laboratory validation.

Science.gov (United States)

Price, Randi; Wan, Ping

2010-01-01

A potentiometric titration for determining the quaternary ammonium compounds (QAC) commonly found in antimicrobial products was validated by a single laboratory. Traditionally, QACs were determined by using a biphasic (chloroform and water) manual titration procedure. Because of safety considerations regarding chloroform, as well as the subjectivity of color indicator-based manual titration determinations, an automatic potentiometric titration procedure was tested with quaternary nitrogen product formulations. By using the Metrohm Titrando system coupled with an ionic surfactant electrode and an Ag/AgCl reference electrode, titrations were performed with various QAC-containing formulation products/matrixes; a standard sodium lauryl sulfate solution was used as the titrant. Results for the products tested are sufficiently reproducible and accurate for the purpose of regulatory product enforcement. The robustness of the method was measured by varying pH levels, as well as by comparing buffered versus unbuffered titration systems. A quantitation range of 1-1000 ppm quaternary nitrogen was established. Eight commercially available antimicrobial products covering a variety of matrixes were assayed; the results obtained were comparable to those obtained by the manual titration method. Recoveries of 94 to 104% were obtained for spiked samples.

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.

Mixed system of ionic liquid and non-ionic surfactants in aqueous media: Surface and thermodynamic properties

International Nuclear Information System (INIS)

Bhatt, Darshak; Maheria, Kalpana; Parikh, Jigisha

2014-01-01

Highlights: • Interaction of ionic liquid and ethylene oxide based non-ionic surfactants in aqueous media. • Evaluation of various surface properties and thermodynamic parameters. • Micellar growth ensues from exothermic to endothermic with increase in temperature. • Micelle formation is enthalpy driven at low temperature and entropy driven at higher temperature. • The micellization power and adsorption proficiency decreased at high IL concentrations. - Abstract: The mixed system of ionic liquid (IL) tetraethyl ammonium tetrafluoroborate [TEA(BF 4 )] and numerous ethylene oxide based non-ionic surfactants in aqueous media were studied using surface tension, viscosity and dynamic light scattering (DLS) measurements. Various surface properties like critical micelle concentration (cmc), maximum surface excess concentration (Γ max ), minimum surface area per surfactant molecule (A min ), surface tension at the cmc (γ cmc ), adsorption efficiency (pC 20 ), and effectiveness of surface tension reduction (π cmc ) as well as thermodynamic parameters of micellization have been determined. DLS and viscosity measurements revealed that the micellar growth was attributed to the bridged solvophilicity of the POE chain in surfactants at elevated temperatures. In most of the cases, the progression ensues from exothermic to endothermic with increase in temperature of the mixed system. Thermodynamic parameter indicates that the micelle formation process is enthalpy driven at low temperature and entropy driven at higher temperature

Preparation of one-dimensional nickel nanowires by self-assembly process

International Nuclear Information System (INIS)

Wang Dapeng; Sun Dongbai; Yu Hongying; Qiu Zhigang; Meng Huimin

2009-01-01

Self-assembly nickel nanowires were prepared by soft template method in ethylene glycol solutions. The structure and micro-morphology of the products were analyzed using X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). The results showed that the products were pure nickel powders with face-centered cubic (fcc) structure. A growth model was presented to explain the growth mechanism. The effects of pH value, surfactant, reaction temperature and reaction time on the synthesis of nickel nanowires were discussed. When pH > 11.5, the reaction temperature was between 80 deg. C and 90 deg. C, and the concentration of cetyltrimethyl ammonium bromide (CTAB) was higher than 7.0 x 10 -3 , zigzag nickel nanowires with slenderness ratio about 20 could be synthesized

Precursor Mediated Synthesis of Nanostructured Silicas: From Precursor-Surfactant Ion Pairs to Structured Materials

Directory of Open Access Journals (Sweden)

Peter Hesemann

2014-04-01

Full Text Available The synthesis of nanostructured anionic-surfactant-templated mesoporous silica (AMS recently appeared as a new strategy for the formation of nanostructured silica based materials. This method is based on the use of anionic surfactants together with a co-structure-directing agent (CSDA, mostly a silylated ammonium precursor. The presence of this CSDA is necessary in order to create ionic interactions between template and silica forming phases and to ensure sufficient affinity between the two phases. This synthetic strategy was for the first time applied in view of the synthesis of surface functionalized silica bearing ammonium groups and was then extended on the formation of materials functionalized with anionic carboxylate and bifunctional amine-carboxylate groups. In the field of silica hybrid materials, the “anionic templating” strategy has recently been applied for the synthesis of silica hybrid materials from cationic precursors. Starting from di- or oligosilylated imidazolium and ammonium precursors, only template directed hydrolysis-polycondensation reactions involving complementary anionic surfactants allowed accessing structured ionosilica hybrid materials. The mechanistic particularity of this approach resides in the formation of precursor-surfactant ion pairs in the hydrolysis-polycondensation mixture. This review gives a systematic overview over the various types of materials accessed from this cooperative ionic templating approach and highlights the high potential of this original strategy for the formation of nanostructured silica based materials which appears as a complementary strategy to conventional soft templating approaches.

Photocatalytic degradation of hexadecyl trimethyl ammonium chloride C/sub 19/H/sub 42/NCl

International Nuclear Information System (INIS)

Hassan, M.U.; Anwar, J.; Saif, M.J.

2008-01-01

Surfactants in the environment are a prerequisite for the sustainable development of human health and ecosystems. Surfactants are important in daily life in households as well as in industrial cleansing processes. It is important to have a detailed knowledge about their lifetime in the environment, their biodegradability in wastewater treatment plants and in natural waters, and their ecotoxicity. Most of the issues on environmental acceptability focus on the effects on the environment associated with the use and disposal of these surfactants. These effects are taken into account by a risk assessment. The first step in a risk assessment is an estimate of the concentrations of surf act ants in the environmental compartment of interest, such as wastewater treatment plant effluents, surface waters, sediments, and soils. This estimate is generated either by actual measurement or by prediction via modelling. The measured or predicted concentrations are then compared to the concentrations of surfactant known to be toxic to organisms living in these environmental compartments. There are many situations where industry is producing both heavy metals ions and organic pollutants, Successful treatment of effluents of this type to achieve legislative compliance will depend on whether the heavy metals effect the process of degradation of the organic species and whether the presence of organic molecules hinder the process of removal of heavy metals. Degradation of cationic surfactant was studied with a photolytic cell system. Compressed air was used as oxidant and the temperature was maintained at 25-30 degree C. Effect of UV source, hydrogen peroxide (H/sub 2/O/sub 2/) and titanium (TiO/sub 2/) on Hexadecyl trimethyl ammonium Chloride C/sub 19/H/sub 42/NCl were recorded. HPLC and IR were used to analyse to study the rate of degradation of C/sub 19/H/sub 42/NCl. (author)

Mineralization of surfactants by the microbiota of submerged plant detritus.

Science.gov (United States)

Federle, T W; Ventullo, R M

1990-02-01

In wetlands and canopied bodies of water, plant detritus is an important source of carbon and energy. Detrital materials possess a large surface area for sorption of dissolved organics and are colonized by a large and diverse microbiota. To examine the biodegradation of surfactants by these microorganisms, submerged oak leaves were obtained from a laundromat wastewater pond, its overflow, and a pristine control pond. Leaves were cut into disks and incubated in sterile water amended with 50 mug of C-labeled linear alkylbenzene sulfonate (LAS), linear alcohol ethoxylate, stearyltrimethyl ammonium chloride, distearyldimethyl ammonium chloride, benzoic acid, or mixed amino acids per liter. Sorption of the test compounds to the detritus and evolution of CO(2) were followed with time. All of the compounds sorbed to the detritus to various degrees, with LAS and stearyltrimethyl ammonium chloride the most sorptive and benzoic acid the least. All compounds were mineralized without a lag. With leaves from the laundromat wastewater pond, half-lives were 12.6 days for LAS, 8.4 days for linear alcohol ethoxylate, 14.2 days for stearyltrimethyl ammonium chloride, 1.0 days for benzoic acid, and 2.7 days for mixed amino acids. Mineralization of LAS and linear alcohol ethoxylate by control pond leaves was slower and exhibited an S-shaped rather than a typical first-order pattern. This study shows that detritus represents a significant site of surfactant removal in detritus-rich systems.

Mineralization of surfactants by the microbiota of submerged plant detritus

International Nuclear Information System (INIS)

Federle, T.W.; Ventullo, R.M.

1990-01-01

In wetlands and canopied bodies of water, plant detritus is an important source of carbon and energy. Detrital materials possess a large surface area for sorption of dissolved organics and are colonized by a large and diverse microbiota. To examine the biodegradation of surfactants by these microorganisms, submerged oak leaves were obtained from a laundromat wastewater pond, its overflow, and a pristine control pond. Leaves were cut into disks and incubated in sterile water amended with 50 μg of 14 C-labeled linear alkylbenzene sulfonate (LAS), linear alcohol ethoxylate, stearyltrimethyl ammonium chloride, distearyldimethyl ammonium chloride, benzoic acid, or mixed amino acids per liter. Sorption of the test compounds to the detritus and evolution of 14 CO 2 were followed with time. All of the compounds sorbed to the detritus to various degrees, with LAS and stearyltrimethyl ammonium chloride the most sorptive and benzoic acid the least. All compounds were mineralized without a lag. With leaves from the laundromat wastewater pond, half-lives were 12.6 days for LAS, 8.4 days for linear alcohol ethoxylate, 14.2 days for stearyltrimethyl ammonium chloride, 1.0 days for benzoic acid, and 2.7 days for mixed amino acids. Mineralization of LAS and linear alcohol ethoxylate by control pond leaves was slower and exhibited an S-shaped rather than a typical first-order pattern. This study shows that detritus represents a significant site of surfactant removal in detritus-rich systems

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...

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

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.

Structural characterization and antimicrobial properties of silver nanoparticles prepared by inverse microemulsion method.

Science.gov (United States)

Wani, Irshad A; Khatoon, Sarvari; Ganguly, Aparna; Ahmed, Jahangeer; Ahmad, Tokeer; Manzoor, Nikhat

2013-01-01

Silver nanoparticles have been synthesized in the inverse microemulsions formed using three different surfactants viz., cetyl-trimethyl ammonium bromide (CTAB), Tergitol and Triton X-100. We have done a systematic study of the effect of the surfactants on the particle size and properties of the silver nanoparticles. Microscopic studies show the formation of spheres, cubes and discs shaped silver nanostructures with the size in the range from 8 to 40 nm. Surface plasmon resonance (SPR) peak was observed around 400 nm and 500 nm. In addition to SPR some extra peaks have also been observed due to the formation of silver metal clusters. The surface area increases from 3.45 to 15.06 m(2)/g with decreasing the size of silver nanoparticles (40-8 nm). To investigate the antimicrobial activity of silver nanoparticles, the nanoparticles were tested against the yeast, Candida albicans and the bacterium, E. coli. The results suggest very good antimicrobial activity of the silver nanoparticles against the test microbes. The mode of action of the antimicrobial activity was also proposed. Copyright © 2012 Elsevier B.V. All rights reserved.

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.

Entropy of adsorption of mixed surfactants from solutions onto the air/water interface

Science.gov (United States)

Chen, L.-W.; Chen, J.-H.; Zhou, N.-F.

1995-01-01

The partial molar entropy change for mixed surfactant molecules adsorbed from solution at the air/water interface has been investigated by surface thermodynamics based upon the experimental surface tension isotherms at various temperatures. Results for different surfactant mixtures of sodium dodecyl sulfate and sodium tetradecyl sulfate, decylpyridinium chloride and sodium alkylsulfonates have shown that the partial molar entropy changes for adsorption of the mixed surfactants were generally negative and decreased with increasing adsorption to a minimum near the maximum adsorption and then increased abruptly. The entropy decrease can be explained by the adsorption-orientation of surfactant molecules in the adsorbed monolayer and the abrupt entropy increase at the maximum adsorption is possible due to the strong repulsion between the adsorbed molecules.

Facile synthesis of ammonium vanadate nanofibers by using reflux in aqueous V{sub 2}O{sub 5} solution with ammonium persulfate

Energy Technology Data Exchange (ETDEWEB)

Lee, Se Hun [Department of Convergence Nanoscience, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Koo, Jun Mo [Department of Organic and Nano Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Oh, Seong Geun, E-mail: seongoh@hanyang.ac.kr [Department of Chemical Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Im, Seung Soon, E-mail: imss007@hanyang.ac.kr [Department of Convergence Nanoscience, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Department of Organic and Nano Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

2017-06-15

Ammonium vanadate nanofibers were synthesized by simple reflux method in aqueous V{sub 2}O{sub 5} solution with ammonium persulfate without relying on surfactants, catalysts, harmful solvents and autoclave. The degree of intercalation by cationic ammonium ions into the crystal structure of vanadium oxide along with its change in chemical composition were analyzed by thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR). The morphological changes toward nanofiber structure, having diameter of 20–30 nm and a few μm length, were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influences of synthetic conditions, such as reaction time and concentration of sulfate (SO{sub 4}{sup 2-}), on the crystal structures and morphologies of the resulting products have investigated. As a result, the ammonium vanadate nanofiber was formed in a short reaction time through a simple reflux method and yielded comparable electrical conductivity 1.47 × 10{sup -2} S/cm. - Highlights: • Ammonium vanadate nanofiber (AVFr) was prepared by simple reflux method. • AVFr yielded comparable electrical conductivity 1.47 × 10{sup -2} S/cm. • The electrical conductivity was improved by the increased amount of ammonium ion. • Sulfate ions (SO{sub 4}{sup 2-}) play a crucial role in controlling the morphology of nanofiber.

Dyes adsorption blue vegetable and blue watercolor by natural zeolites modified with surfactants

International Nuclear Information System (INIS)

Jardon S, C. C.; Olguin G, M. T.; Diaz N, M. C.

2009-01-01

In this work was carried out the dyes removal blue vegetable and blue watercolor of aqueous solutions, to 20 C, at different times and using a zeolite mineral of Parral (Chihuahua, Mexico) modified with hexadecyl trimethyl ammonium bromide or dodecyl trimethyl ammonium bromide. The zeolite was characterized before and after of its adaptation with NaCl and later with HDTMABr and DTMABr. For the materials characterization were used the scanning electron microscopy of high vacuum; elementary microanalysis by X-ray spectroscopy of dispersed energy and X-ray diffraction techniques. It was found that the surfactant type absorbed in the zeolite material influences on the adsorption process of the blue dye. Likewise, the chemical structure between the vegetable blue dye and the blue watercolor, determines the efficiency of the color removal of the water, by the zeolites modified with the surfactants. (Author)

Adsorption of naphthalene and ozone on atmospheric air/ice interfaces coated with surfactants: a molecular simulation study.

Science.gov (United States)

Liyana-Arachchi, Thilanga P; Valsaraj, Kalliat T; Hung, Francisco R

2012-03-15

The adsorption of gas-phase naphthalene and ozone molecules onto air/ice interfaces coated with different surfactant species (1-octanol, 1-hexadecanol, or 1-octanal) was investigated using classical molecular dynamics (MD) simulations. Naphthalene and ozone exhibit a strong preference to be adsorbed at the surfactant-coated air/ice interfaces, as opposed to either being dissolved into the bulk of the quasi-liquid layer (QLL) or being incorporated into the ice crystals. The QLL becomes thinner when the air/ice interface is coated with surfactant molecules. The adsorption of both naphthalene and ozone onto surfactant-coated air/ice interfaces is enhanced when compared to bare air/ice interface. Both naphthalene and ozone tend to stay dissolved in the surfactant layer and close to the QLL, rather than adsorbing on top of the surfactant molecules and close to the air region of our systems. Surfactants prefer to orient at a tilted angle with respect to the air/ice interface; the angular distribution and the most preferred angle vary depending on the hydrophilic end group, the length of the hydrophobic tail, and the surfactant concentration at the air/ice interface. Naphthalene prefers to have a flat orientation on the surfactant coated air/ice interface, except at high concentrations of 1-hexadecanol at the air/ice interface; the angular distribution of naphthalene depends on the specific surfactant and its concentration at the air/ice interface. The dynamics of naphthalene molecules at the surfactant-coated air/ice interface slow down as compared to those observed at bare air/ice interfaces. The presence of surfactants does not seem to affect the self-association of naphthalene molecules at the air/ice interface, at least for the specific surfactants and the range of concentrations considered in this study.

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.

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.

Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite

Energy Technology Data Exchange (ETDEWEB)

Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik, E-mail: niknizam@fbb.utm.my

2016-02-01

The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550 °C, 5 h) and this material has excellent performance as an antibacterial agent after silver ions loading. - Highlights: • Thermal treatment was used to regenerate surfactant modified zeolite. • The regenerated NaY zeolite formed was added with different silver loadings. • Regenerated AgY zeolite was tested for antibacterial activity on E. coli and S. aureus. • The antibacterial activity increased with increased of the amount of silver loadings. • The zeolite structure did not change with thermal and modification

Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite

International Nuclear Information System (INIS)

Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik

2016-01-01

The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550 °C, 5 h) and this material has excellent performance as an antibacterial agent after silver ions loading. - Highlights: • Thermal treatment was used to regenerate surfactant modified zeolite. • The regenerated NaY zeolite formed was added with different silver loadings. • Regenerated AgY zeolite was tested for antibacterial activity on E. coli and S. aureus. • The antibacterial activity increased with increased of the amount of silver loadings. • The zeolite structure did not change with thermal and modification

Conformational transition of κ-casein in micellar environment: Insight from the tryptophan fluorescence

Science.gov (United States)

Mishra, Smruti; Meher, Geetanjali; Chakraborty, Hirak

2017-11-01

Intrinsically disordered proteins (IDPs) are under intense analysis due to their structural flexibility and importance in biological functions. Minuscule modulation in the microenvironment induces significant conformational changes in IDPs, and these non-native conformations of the IDPs often induce aggregation and cause cell death. Changes in the membrane composition often change the microenvironment, which promote conformational change and aggregation of IDPs. κ-Casein, an important milk protein, belongs to the class of IDPs containing net negative charges. In this present work, we have studied the interaction of κ-casein with cetyltrimethyl ammonium bromide (CTAB), a positively charged surfactant, utilizing various steady state fluorescence, time-resolved fluorescence and circular dichroism spectroscopy. Our results clearly indicate that κ-casein undergoes at least two conformational transitions in presence of various concentrations of CTAB. The intrinsically disordered κ-casein assumes a partially folded conformation at lower concentration of CTAB, which adopts an unstructured conformation at higher concentration of CTAB. The partially folded conformation of κ-casein at a lower CTAB concentration might be induced by the favorable electrostatic interaction between the positively charged surfactant headgroup and net negative charges of the protein, whereas surfactant nature of CTAB is being pronounced at higher concentration of CTAB.

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

Adsorption of different amphiphilic molecules onto polystyrene latices.

Science.gov (United States)

Jódar-Reyes, A B; Ortega-Vinuesa, J L; Martín-Rodríguez, A

2005-02-15

In order to know the influence of the surface characteristics and the chain properties on the adsorption of amphiphilic molecules onto polystyrene latex, a set of experiments to study the adsorption of ionic surfactants, nonionic surfactants and an amphiphilic synthetic peptide on different latex dispersions was performed. The adsorbed amount versus the equilibrium surfactant concentration was determined. The main adsorption mechanism was the hydrophobic attraction between the nonpolar tail of the molecule and the hydrophobic regions of the latex surface. This attraction overcame the electrostatic repulsion between chains and latex surface with identical charge sign. However, the electrostatic interactions chain-surface and chain-chain also played a role. General patterns for the adsorption of ionic chains on charged latex surfaces could be established. Regarding the shape, the isotherms presented different plateaus corresponding to electrostatic effects and conformational changes. The surfactant size also affects the adsorption results: the higher the hydrophilic moiety in the surfactant molecule the lower the adsorbed amount.

Determination of N-acetylcysteine via its effect on the aggregation of gold nanoparticles

International Nuclear Information System (INIS)

Sierra-Rodero, M.; Fernandez-Romero, J.M.; Gomez-Hens, A.

2011-01-01

The effect of thiol compounds on the kinetics of the aggregation of gold nanoparticles in the presence of the cationic surfactant cetyltrimethyl ammonium bromide has been studied. It was applied to the determination of N-acetylcysteine using the stopped-flow mixing technique along with light scattering detection. The signal obtained was measured after about 5 s, and gave the analytical information for a calibration graph in the concentration range from 2.9 to 60 μmol L -1 of N-acetylcysteine, and a detection limit of 0.87 μmol L- 1. The effect of other thiols on the system is also described. The relative standard deviation ranges between 0.6% and 3.5%. The method was applied to the determination of N-acetylcysteine in several pharmaceutical samples with recoveries that range from 97.7% to 101.1% (author)

CTAB assisted synthesis of tungsten oxide nanoplates as an efficient low temperature NOX sensor

Science.gov (United States)

Mehta, Swati S.; Tamboli, Mohaseen S.; Mulla, Imtiaz S.; Suryavanshi, Sharad S.

2018-02-01

Tungsten oxide nanoplates with porous morphology were effectively prepared by acidification using CTAB (HexadeCetyltrimethyl ammonium bromide) as a surfactant. For characterization, the synthesized materials were subjected to X-Ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), UV-Visible spectroscopy (UV-Vis) and surface area (BET) measurements. The morphology and size of the particles were controlled by solution acidity. The BET results confirmed that the materials are well crystallized and mesoporous in nature. The nanocrystalline powder was used to prepare thick films by screen printing on alumina substrate for the investigation of gas sensing properties. The gas response measurements revealed that the samples acidified using 10 M H2SO4 exhibits highest response of 91% towards NOX at optimum temperature of 200 °C for 100 ppm, and it also exhibits 35% response at room temperature.

Surfactant assisted synthesis of aluminum doped SrFe{sub 10}Al{sub 2}O{sub 19} hexagonal ferrite

Energy Technology Data Exchange (ETDEWEB)

Neupane, D., E-mail: dneupane@memphis.edu; Wang, L.; Mishra, S. R. [Department of Physics, The University of Memphis, Memphis, Tennessee 38152 (United States); Poudyal, N.; Liu, J. P. [Department of Physics, The University of Texas, Arlington, Texas 76019 (United States)

2015-05-07

M-type aluminum doped SrFe{sub 10}Al{sub 2}O{sub 19} were synthesized via co-precipitation method using cetyltrimethyl ammonium bromide (CTAB) as a surfactant. The effects of CTAB content (x = 0, 1, 3, and 9 wt. %) on the formation, structure, morphology, magnetic, and dielectric properties of the SrFe{sub 10}Al{sub 2}O{sub 19} nanoparticles were investigated. X-ray diffraction results show elimination of α-Fe{sub 2}O{sub 3} phase from samples prepared using CTAB. Morphological changes including grain and crystallite size was noticed with the increase in the CTAB content. With the increase in CTAB, powder particles grew in hexagonal plates. A linear increase in saturation magnetization, Ms, with CTAB content was observed from 56.5 emu/g at 0% CTAB to 66.4 emu/g at 9% CTAB. This is a net increase of 17.5% in Ms. The coercivity (Hc ∼ 5700 Oe) of sample reached maximum at 1% CTAB and reduced with further CTAB content reaching to a minimum value of 4488 Oe at 9% CTAB. A slight increase in Curie temperature (735 K) was also observed for samples synthesized using CTAB as compared to that of sample prepared in the absence of CTAB (729 K). Samples synthesized with CTAB show higher dielectric constants as compared to samples prepared without CTAB, while dielectric constant for all samples show decrease in value with the increase in frequency. These results imply that CTAB may act as a crystallization master, controlling the nucleation and growth of SrFe{sub 10}Al{sub 2}O{sub 19} crystal. The study delineates the scope of improving magnetic properties of ferrites without substitution of metal ions.

Turbulence and Cavitation Suppression by Quaternary Ammonium Salt Additives.

Science.gov (United States)

Naseri, Homa; Trickett, Kieran; Mitroglou, Nicholas; Karathanassis, Ioannis; Koukouvinis, Phoevos; Gavaises, Manolis; Barbour, Robert; Diamond, Dale; Rogers, Sarah E; Santini, Maurizio; Wang, Jin

2018-05-16

We identify the physical mechanism through which newly developed quaternary ammonium salt (QAS) deposit control additives (DCAs) affect the rheological properties of cavitating turbulent flows, resulting in an increase in the volumetric efficiency of clean injectors fuelled with diesel or biodiesel fuels. Quaternary ammonium surfactants with appropriate counterions can be very effective in reducing the turbulent drag in aqueous solutions, however, less is known about the effect of such surfactants in oil-based solvents or in cavitating flow conditions. Small-angle neutron scattering (SANS) investigations show that in traditional DCA fuel compositions only reverse spherical micelles form, whereas reverse cylindrical micelles are detected by blending the fuel with the QAS additive. Moreover, experiments utilising X-ray micro computed tomography (micro-CT) in nozzle replicas, quantify that in cavitation regions the liquid fraction is increased in the presence of the QAS additive. Furthermore, high-flux X-ray phase contrast imaging (XPCI) measurements identify a flow stabilization effect in the region of vortex cavitation by the QAS additive. The effect of the formation of cylindrical micelles is reproduced with computational fluid dynamics (CFD) simulations by including viscoelastic characteristics for the flow. It is demonstrated that viscoelasticity can reduce turbulence and suppress cavitation, and subsequently increase the injector's volumetric efficiency.

Polarization-dependent NEXAFS study of adsorption of long-chain surfactants on mechanically milled iron powder

Energy Technology Data Exchange (ETDEWEB)

Syugaev, A.V., E-mail: syual@mail.ru; Maratkanova, A.N.

2014-08-15

Highlights: • Plate-like particles modified with surfactant molecules were obtained under high-energy ball milling. • Adsorption layers were studied with polarization-dependent NEXAFS spectroscopy. • For the first time, arrangement of surfactants molecules on the powdered metal surface has been determined. • Tails of surfactant molecules (C-F/C-H) are shown to be oriented perpendicular to the particle surface. • Arrangement of carboxylate groups on the particle surfaces is discussed. - Abstract: In this work we have demonstrated the possibility of using the polarization-dependent NEXAFS spectra to study the structure of organic layers at the surface of powdered materials with plate-like shaped particles. The polarization dependence of the NEXAFS spectra may be easily obtained by just changing the angle between the X-ray beam direction and the substrate onto which the powder particles are set. For the first time, we have carried out a detailed study of the surfactant layers (n-perfluorononanoic and stearic acid), which are formed at the surface of iron plate-like particles under mechanical milling of iron powder with an addition of corresponding surfactants. The surfactant molecules are predominantly oriented perpendicular to the surface of the mechanically milled particles. Such orientation is similar to the arrangement of the molecules in the layers formed under equilibrium conditions, e.g. deposition from solutions. The changes in the chemical environment occurring in the molecule tails (defluorination or dehydrogenation) under mechanochemical treatment, do not result in a significant change in the molecular orientation and disordering of the adsorbed layer.

Effects of pyrithiones and surfactants on zinc and enzyme levels in rabbits.

Science.gov (United States)

Spiker, R C; Ciuchta, H P

1980-04-01

The effects of zinc pyrithione (ZnPT) and sodium pyrithione (NaPT), including the influence of various vehicles, upon whole blood and plasma zinc levels and serum alkaline phosphatase (SAP) have been investigated in rabbits following dermal and/or iv administration. Two such vehicles, ammonium lauryl sulfate (ALS) and triethanolamine lauryl sulfate, affected zinc homeostasis differently than the pyrithiones, in that, unlike the pyrithiones, no whole blood changes were observed, although there were delayed and sustained declines in plasma zinc and SAP values. These changes were most likely related to the skin irritation caused by the surfactants. In contrast, NaPT-dimethyl sulfoxide (DMSO) dermal and iv exposures produced rapid decreases in plasma zinc followed by quick recovery, coupled with smaller and unsustained declines in SAP. Large increases in whole blood zinc were also observed in both cases, as well as in a ZnPT-DMSO iv exposure. DMSO itself had no effects on the measured parameters. Experiments involving combinations of the pyrithiones and ALS demonstrated effects on zinc homeostasis that were attributable to both substances, i.e. large increases in whole blood zinc (PT effect), quick drops in plasma zinc (PT effect) and slowly recovering plasma zinc and SAP values (surfactant effect). The chelating nature of the PT molecule may have been responsible for some of the observed changes in zinc distribution.

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.

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

Photochemical key steps in the synthesis of surfactants from furfural-derived intermediates.

Science.gov (United States)

Gassama, Abdoulaye; Ernenwein, Cédric; Hoffmann, Norbert

2009-01-01

Furfural is oxidized to 2[5H]-furanone by using hydrogen peroxide or to 5-hydroxy-2[5H]-furanone by using photo-oxygenation. An amine function is introduced by photochemically induced radical addition of tertiairy amines, some of which carry an n-alkyl side chain as hydrophobic moiety. These amines are produced from fatty aldehydes and cyclic secondary amines. The resulting adducts are transformed into amphoteric surfactants possessing an ammonium and a carboxylate function. Amphoteric (pK(N) and isoelectric point) and surfactant properties such as the critical micelle concentration and the adsorption efficiency are determined.

A high-yield, one-step synthesis of surfactant-free gold nanostars and numerical study for single-molecule SERS application

Energy Technology Data Exchange (ETDEWEB)

Chatterjee, S.; Ringane, A. B.; Arya, A.; Das, G. M.; Dantham, V. R., E-mail: dantham@iitp.ac.in; Laha, R. [Indian Institute of Technology Patna, Department of Physics (India); Hussian, S. [Indian Institute of Technology Patna, Department of Chemistry (India)

2016-08-15

We report a high-yield synthesis of star-shaped gold nanostructures in one step, using a new surfactant-free wet chemistry method. Compared to the existing reports, these nanostars were found to have longer and sharper spikes anchored uniformly on the surface of the spherical core, allowing at least a few hot spots irrespective of the incident light polarization. The average experimental values of core radius and spike length were found to be 88.5 and 72 nm, respectively. Using these values in numerical simulations, the local electric field enhancement (η) and localized surface plasmon resonance (LSPR) spectrum were obtained. Moreover, the single-molecule surface-enhanced Raman scattering (SERS) enhancement factor was found to vary from 10{sup 10} to 10{sup 13} depending on the excitation wavelengths. Our theoretical calculations suggest that these nanostructures can be used to fabricate efficient SERS-based biosensors for the detection of single molecules in real time and for predicting structural information of single molecules.

Quartz crystal microbalance sensor using ionophore for ammonium ion detection.

Science.gov (United States)

Kosaki, Yasuhiro; Takano, Kosuke; Citterio, Daniel; Suzuki, Koji; Shiratori, Seimei

2012-01-01

Ionophore-based quartz crystal microbalance (QCM) ammonium ion sensors with a detection limit for ammonium ion concentrations as low as 2.2 microM were fabricated. Ionophores are molecules, which selectively bind a particular ion. In this study, one of the known ionophores for ammonium, nonactin, was used to detect ammonium ions for environmental in-situ monitoring of aquarium water for the first time. To fabricate the sensing films, poly(vinyl chloride) was used as the matrix for the immobilization of nonactin. Furthermore, the anionic additive, tetrakis (4-chlorophenyl) borate potassium salt and the plasticizer dioctyl sebacate were used to enhance the sensor properties. The sensor allowed detecting ammonium ions not only in static solution, but also in flowing water. The sensor showed a nearly linear response with the increase of the ammonium ion concentration. The QCM resonance frequency increased with the increase of ammonium ion concentration, suggesting a decreasing weight of the sensing film. The detailed response mechanism could not be verified yet. However, from the results obtained when using a different plasticizer, nitrophenyl octyl ether, it is considered that this effect is caused by the release of water molecules. Consequently, the newly fabricated sensor detects ammonium ions by discharge of water. It shows high selectivity over potassium and sodium ions. We conclude that the newly fabricated sensor can be applied for detecting ammonium ions in aquarium water, since it allows measuring low ammonium ion concentrations. This sensor will be usable for water quality monitoring and controlling.

Equilibrium of adsorption of mixed milk protein/surfactant solutions at the water/air interface.

Science.gov (United States)

Kotsmar, C; Grigoriev, D O; Xu, F; Aksenenko, E V; Fainerman, V B; Leser, M E; Miller, R

2008-12-16

Ellipsometry and surface profile analysis tensiometry were used to study and compare the adsorption behavior of beta-lactoglobulin (BLG)/C10DMPO, beta-casein (BCS)/C10DMPO and BCS/C12DMPO mixtures at the air/solution interface. The adsorption from protein/surfactant mixed solutions is of competitive nature. The obtained adsorption isotherms suggest a gradual replacement of the protein molecules at the interface with increasing surfactant concentration for all studied mixed systems. The thickness, refractive index, and the adsorbed amount of the respective adsorption layers, determined by ellipsometry, decrease monotonically and reach values close to those for a surface covered only by surfactant molecules, indicating the absence of proteins from a certain surfactant concentration on. These results correlate with the surface tension data. A continuous increase of adsorption layer thickness was observed up to this concentration, caused by the desorption of segments of the protein and transforming the thin surface layer into a rather diffuse and thick one. Replacement and structural changes of the protein molecules are discussed in terms of protein structure and surface activity of surfactant molecules. Theoretical models derived recently were used for the quantitative description of the equilibrium state of the mixed surface layers.

Surfactant induced complex formation and their effects on the interfacial properties of seawater.

Science.gov (United States)

Guzmán, Eduardo; Santini, Eva; Benedetti, Alessandro; Ravera, Francesca; Ferrari, Michele; Liggieri, Libero

2014-11-01

The effect of a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB), on the interfacial properties of seawater has been studied by dynamic and equilibrium surface tension and by dilational rheology essays. Important modifications of the surface tension and dilational rheology response have been observed already at the very low CTAB concentrations, where the effects due to the high ionic strength are negligible. The comparison with the effects of CTAB in different seawater models, or in natural seawater fractions, points out the establishment of strong interactions between the surfactant molecules and the lipophilic fraction of organic material dispersed/dissolved in seawater, affecting the interfacial activity of the molecules. Considering the biochemical richness of seawater, these results can be explained assuming interaction mechanisms and adsorption schemes similar to those speculated for protein and other macromolecules in the presence of surfactants, which in fact show similar features. Thus already at the low concentrations the surfactant molecules form highly surface-active complexes with part of the organic fraction of seawater. At the larger surfactant concentrations these complexes compete for adsorption with an excess of free CTAB molecules which, according to the thermodynamic conditions, are most favoured to occupy the liquid interface. The results of this study underline the important role of the sea organic content in enhancing the surface-activity of surfactants, which is relevant for a deeper understand of the direct and indirect effects of these types of pollutants on the physico-chemical environment in the sea coastal areas and develop mitigation strategies. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

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.

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.

A simplified treatment of surfactant effects on cloud drop activation

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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.

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.

Quaternary ammonium compounds – New occupational hazards

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Agnieszka Lipińska-Ojrzanowska

2014-10-01

Full Text Available Quaternary ammonium compounds (QACs, quats belong to organic ionic chemical agents which display unique properties of both surfactants and disinfectants. Their wide distribution in the work environment and also in private households brings about new occupational hazards. This paper reviews reports about the health effects of QACs. QACs could play a role of sensitizers and irritants to the skin and mucous membranes. It is suspected that particular QACs can display an immunologic crossreactivity between each other and with other chemical compounds containing ammonium ion, such as muscle relaxants widely used in anesthesia. They may promote the development of airway allergy, however, the background mechanisms are still unclear and need to be further investigated. Until now, a few cases of occupational asthma induced by QACs have been described and their involvement in contact dermatitis has been documented. The possibility of anaphylaxis due to QACs cannot be excluded as well. Med Pr 2014;65(5:675–682

Synthesis of magnetic core-shell structure Fe3O4@MCM-41 nanoparticle by vesicles in aqueous solutions☆

Institute of Scientific and Technical Information of China (English)

Weiming Song; Xuesong Liu; Ying Yang; Xuejia Han; Qigang Deng

2015-01-01

In this study, magnetic core–shel structure Fe3O4@MCM-41 nanoparticles were synthesized with vesicles as soft templates. In the preparation, FeCl2 and tetraethy orthosilicate (TEOS) were selected as Fe processor and Si pre-cursor, respectively. Stable vesicles first formed in 0.03 mol·L−1 1:2 mixture of anionic surfactant sodium dode-cyl sulfate and cationic surfactant cetyltrimethyl ammonium bromide. Then, TEOS was added in the vesicle aqueous solution, leading to a highly dispersed solution. After high-temperature calcination, Fe3O4@MCM-41 nanoparticles were obtained. Their structure and morphology were characterized by Saturn Digisizer, transmis-sion electron microscope and vibrating sample magneto-meter. The results indicate that the vesicles are spherical and their size could be tuned between 20 and 50 nm. The average grain diameter of synthesize magnetic core–shel Fe3O4@MCM-41 particles is 100–150 nm and most of them are in el iptical shape. The dispersion of magnet-ic particles is very good and magnetization values are up to 33.44 emu·g−1, which are superior to that of other Fe3O4 materials reported.

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.

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

Synthesis and characterization of hexagonal nano-sized nickel selenide by simple hydrothermal method assisted by CTAB

Energy Technology Data Exchange (ETDEWEB)

Sobhani, Azam [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Davar, Fatemeh [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of)

2011-07-01

Nano-sized nickel selenide powders have been successfully synthesized via an improved hydrothermal route based on the reaction between NiCl{sub 2}.6H{sub 2}O, SeCl{sub 4} and hydrazine (N{sub 2}H{sub 4}.H{sub 2}O) in water, in present of cetyltrimethyl ammonium bromide (CTAB) as surfactant, at various conditions. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray energy dispersive spectroscopy analysis. Effects of temperature, reaction time and reductant agent on the morphology, the particle sizes and the phase of the final products have been investigated. It was found that the phase and morphology of the products could be greatly influenced by these parameters. The synthesis procedure is simple and uses less toxic reagents than the previously reported methods. Photoluminescence (PL) was used to study the optical properties of NiSe samples.

Temperature-dependent adsorption of surfactant molecules and associated crystallization kinetics of noncentrosymmetric Fe(IO{sub 3}){sub 3} nanorods in microemulsions

Energy Technology Data Exchange (ETDEWEB)

El-Kass, Moustafa [Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy Le Vieux Cedex (France); Ladj, Rachid [Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy Le Vieux Cedex (France); Université Lyon1, CNRS, UMR 5007, LAGEP, CPE, 43 bd 11 Novembre 1918, F-69622 Villeurbanne (France); Mugnier, Yannick, E-mail: Yannick.Mugnier@univ-savoie.fr [Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy Le Vieux Cedex (France); Le Dantec, Ronan [Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy Le Vieux Cedex (France); Hadji, Rachid [Institut Jean Lamour, UMR CNRS n°7198, Université de Lorraine, Nancy 1, BP 239, 54506 Vandoeuvre-lès-Nancy Cedex (France); Marty, Jean-Christophe [Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy Le Vieux Cedex (France); Rouxel, Didier [Institut Jean Lamour, UMR CNRS n°7198, Université de Lorraine, Nancy 1, BP 239, 54506 Vandoeuvre-lès-Nancy Cedex (France); Durand, Christiane [Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy Le Vieux Cedex (France); Fontvieille, Dominique [UMR CARRTEL (INRA/Université de Savoie), Laboratoire de Microbiologie Aquatique, BP 511, 74203 Thonon Cedex (France); Rogalska, Ewa [Structure et Réactivité des Systèmes Moléculaires Complexes, UMR 7565, Nancy Université, BP 70239, 54506 Vandoeuvre-lès-Nancy cedex (France); and others

2013-11-15

Graphical abstract: - Highlights: • Crystallization of Fe(IO{sub 3}){sub 3} in microemulsions probed by hyper-Rayleigh scattering. • A faster growth and a better shape control of nanorods are obtained at 80 °C. • Different persistent cell deformations are related to the crystallization kinetics. • A temperature-dependent adsorption of surfactants on nanorods is suggested. - Abstract: Aggregation-induced crystallization of iron iodate nanorods within organic–inorganic aggregates of primary amorphous precursors is probed by time-dependent hyper-Rayleigh scattering measurements in Triton X-100 based-microemulsions. In the context of a growing interest of noncentrosymmetric oxide nanomaterials in multi-photon bioimaging, we demonstrate by a combination of X-ray diffraction and electron microscopy that an increase in the synthesis of temperature results in faster crystallization kinetics and in a better shape-control of the final Fe(IO{sub 3}){sub 3} nanorods. For initial microemulsions of fixed composition, room-temperature synthesis leads to bundles of 1–3 μm long nanorods, whereas shorter individual nanorods are obtained when the temperature is increased. Results are interpreted in terms of kinetically unfavorable mesoscale transformations due to the strong binding interactions with Triton molecules. The interplay between the nanorod crystallization kinetics and their corresponding unit cell deformation, evidenced by lattice parameter refinements, is attributed to a temperature-dependent adsorption of surfactants molecules at the organic–inorganic interface.

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

Status of surfactants as penetration enhancers in transdermal drug delivery

Directory of Open Access Journals (Sweden)

Iti Som

2012-01-01

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

Engineered Multifunctional Fluorinated Film Based on Semicontinuous Emulsion Polymerization Using Polymerizable Quaternary Ammonium Emulsifiers

Directory of Open Access Journals (Sweden)

Hongzhu Liu

2018-01-01

Full Text Available Along with society’s progress, high-quality coatings are widely used. Although fluorinated polymers were successfully prepared by semicontinuous emulsion polymerization with surfactants, chlorotrifluoroethylene (CTFE, and acrylate monomers, the optimization collocation of surfactants still has room for improvement. The traditional emulsifiers are physically absorbed onto the surface of latex particles. The latex film generated by latex particles is unstable in water, which limits its application. Herein, a novel series of cationic quaternary ammonium polymerizable surfactant was selected because it can react with CTFE and acrylate monomers and can become a part of the polymers. We also studied the effects of emulsifier type on resultant emulsion properties. In addition, wonderful weatherability, water resistance, and antibacterial and antifouling of the multifunctional fluorinated films were observed, which would open up a bright future for coating industries.

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.

Influence of the chain length of surfactant in the modification of zeolites and clays. Removal of atrazine from water solutions.

Science.gov (United States)

Toledo-Jaldin, Helen Paola; Blanco-Flores, Alien; Sánchez-Mendieta, Víctor; Martín-Hernández, Osnieski

2017-08-30

Removal potentials of a surfactant modified zeolite (SMZ) and clay (SMC) for atrazine adsorption were evaluated. Materials were modified with hexadecyl trimethyl ammonium bromide (HDTMA-Br) and benzyl octadecyl dimethyl ammonium (BODA) chloride considering the critical micellar concentration (CMC) of each one (0.94 and 0.041 meq/L, respectively). The influence of the surfactant was analyzed in detail, particularly the formation of surfactant layers (complete or partial) connected with the length of the surfactant tail (16 and 18 methyl groups or number of carbons in the chain). Raw materials were characterized by XRD and Fourier transform infrared spectroscopy (FTIR), SMZ and SMC were analyzed by FTIR. Results obtained from kinetic adsorption experiments shown that equilibrium time is less for materials modified with HDTMA (8 h) than materials with BODA (10 and 12 h). Materials modified with the largest chain surfactant (BODA) showed more resistance to atrazine masse transference. The chemisorption was presented in the adsorption mechanisms of atrazine and adsorbent materials. Based on the results of adsorption isotherms Langmuir isotherms showed the better correlation coefficients value. The q max is greater for materials modified with BODA (0.9232 and 4.2448 mg/g) than for materials modified with HDTMA (0.6731 and 3.9121 mg/g). Therefore, SMZ and SMC modified with the largest chain surfactant has more affinity for the pesticide. The removal process at high concentration of atrazine depends of the partition process but at lower concentration, it occurs not only by this process but also by absorption process.

Circulating surfactant protein D is decreased in systemic lupus erythematosus

DEFF Research Database (Denmark)

Hoegh, Silje Vermedal; Voss, Anne; Sorensen, Grith Lykke

2009-01-01

Objective. Deficiencies of innate immune molecules like mannan binding lectin (MBL) have been implicated in the pathogenesis of systemic lupus erythematosus (SLE). Surfactant protein D (SP-D) and MBL belong to the same family of innate immune molecules - the collectins, which share important...

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)

Organophilization process of Brazilian bentonite for preparation of polymeric nanocomposites

International Nuclear Information System (INIS)

Oliveira, Carlos I.R. de; Rocha, Marisa C.G.; Ferreira, Joao L.A.N.G.

2015-01-01

Bentonite clay from the municipality of Cubati, PB, was used for the preparation of an organophilic clay. First, the clay was treated with sodium chloride to obtain the homo-ionic sodium clay. The organoclay was, then, obtained from the reaction of homo-ionic clay with the quaternary ammonium salt, cetyltrimethyl ammonium chloride. The natural clay and the modified clays were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The chemical analysis showed a decrease in the concentration of the majority of the metallic oxides when the bentonite was organophilizated. This result is characteristic of the metal cation exchange process by organic salt molecules. The X-ray diffraction confirmed the intercalation among the layers of the clay. The results obtained by FTIR showed the presence of the characteristic groups of the salt in the clay, thus confirming the obtaining of organophilic bentonite. (author)

Nanocomposite formation between alpha-glucosyl stevia and surfactant improves the dissolution profile of poorly water-soluble drug.

Science.gov (United States)

Uchiyama, Hiromasa; Tozuka, Yuichi; Nishikawa, Masahiro; Takeuchi, Hirofumi

2012-05-30

The formation of a hybrid-nanocomposite using α-glucosyl stevia (Stevia-G) and surfactant was explored to improve the dissolution of flurbiprofen (FP). As reported previously, the dissolution amount of FP was enhanced in the presence of Stevia-G, induced by the formation of an FP and Stevia-G-associated nanostructure. When a small amount of sodium dodecyl sulfate (SDS) was present with Stevia-G, the amount of dissolved FP was extremely enhanced. This dissolution-enhancement effect was also observed with the cationic surfactant of dodecyl trimethyl ammonium bromide, but not with the non-ionic surfactant of n-octyl-β-D-maltopyranoside. To investigate the dissolution-enhancement effect of Stevia-G/SDS mixture, the pyrene I(1)/I(3) ratio was plotted versus the Stevia-G concentration. The pyrene I(1)/I(3) ratio of Stevia-G/SDS mixture had a sigmoidal curve at lower Stevia-G concentrations compared to the Stevia-G solution alone. These results indicate that the Stevia-G/SDS mixture provides a hydrophobic core around pyrene molecules at lower Stevia-G concentrations, leading to nanocomposite formation between Stevia-G and SDS. The nanocomposite of Stevia-G/SDS showed no cytotoxicity to Caco-2 cells at a mixture of 0.1% SDS and 1% Stevia-G solution, whereas 0.1% SDS solution showed high toxicity. These results suggest that the nanocomposite formation of Stevia-G/SDS may be useful way to enhance the dissolution of poorly water-soluble drugs without special treatment. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of anionic surfactants during wastewater recycling process by ion pair chromatography with suppressed conductivity detection

Science.gov (United States)

Levine, L. H.; Judkins, J. E.; Garland, J. L.; Sager, J. C. (Principal Investigator)

2000-01-01

A direct approach utilizing ion pairing reversed-phase chromatography coupled with suppressed conductivity detection was developed to monitor biodegradation of anionic surfactants during wastewater recycling through hydroponic plant growth systems and fixed-film bioreactors. Samples of hydroponic nutrient solution and bioreactor effluent with high concentrations (up to 120 mS electrical conductance) of inorganic ions can be analyzed without pretreatment or interference. The presence of non-ionic surfactants did not significantly affect the analysis. Dynamic linear ranges for tested surfactants [Igepon TC-42, ammonium lauryl sulfate, sodium laureth sulfate and sodium alkyl (C10-C16) ether sulfate] were 2 to approximately 500, 1 to approximately 500, 2.5 to approximately 550 and 3.0 to approximately 630 microg/ml, respectively.

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.

Remote control of soft nano-objects by light using azobenzene containing surfactants

Science.gov (United States)

Santer, Svetlana

2018-01-01

We review recent progress in the field of light responsive soft nano-objects. These are systems the shape, size, surface area and surface energy of which can be easily changed by low-intensity external irradiation. Here we shall specifically focus on microgels, DNA molecules, polymer brushes and colloidal particles. One convenient way to render these objects photosensitive is to couple them via ionic and/or hydrophobic interactions with azobenzene containing surfactants in a non-covalent way. The advantage of this strategy is that these surfactants can make any type of charged object light responsive without the need for possibly complicated (and irreversible) chemical conjugation. In the following, we will exclusively discuss only photosensitive surfactant systems. These contain a charged head and a hydrophobic tail into which an azobenzene group is incorporated, which can undergo reversible photo-isomerization from a trans- to a cis-configuration under UV illumination. These kinds of photo-isomerizations occur on a picosecond timescale and are fully reversible. The two isomers in general possess different polarity, i.e. the trans-state is less polar with a dipole moment of usually close to 0 Debye, while the cis-isomer has a dipole moment up to 3 Debye or more, depending on additional phenyl ring substituents. As part of the hydrophobic tail of a surfactant molecule, the photo-isomerization also changes the hydrophobicity of the molecule as a whole and hence its solubility, surface energy, and strength of interaction with other substances. Being a molecular actuator, which converts optical energy in to mechanical work, the azobenzene group in the shape of surfactant molecule can be utilized in order to actuate matter on larger time and length scale. In this paper we show several interesting examples, where azobenzene containing surfactants play the role of a transducer mediating between different states of size, shape, surface energy and spatial arrangement of

Latex imaging by environmental STEM: application to the study of the surfactant outcome in hybrid alkyd/acrylate systems.

Science.gov (United States)

Faucheu, Jenny; Chazeau, Laurent; Gauthier, Catherine; Cavaillé, Jean-Yves; Goikoetxea, Monika; Minari, Roque; Asua, José M

2009-09-01

Among other uses, latexes are a successful alternative to solvent-borne binders for coatings. Efforts are made to produce hybrid nanostructured latexes containing an acrylic phase and an alkyd phase. However, after the film-forming process, the surfactant used to stabilize these latexes remains in the film, and its location can have a drastic effect on the application properties. Among the processing parameters, the alkyd hydrophobicity can strongly influence this location. This article aims at the imaging of these surfactant molecules in two hybrid latexes with different hydrophobicity level of the alkyd resin. A first part of this paper is dedicated to the understanding of the contrast provided by the surfactant in environmental STEM imaging of latexes. Then, the influence of surfactant-polymer affinity on the surfactant location after film-forming of those hybrid alkyd/acrylate latexes is studied by this technique. It is shown that in the hybrid latex with an alkyd shell (obtained with the most hydrophilic resin), the surfactant molecules tend to remain buried in the alkyd phase. Conversely, in the hybrid latex with an acrylate shell (in the case of the most hydrophobic resin), the surfactant molecules tend to gather into islands like in pure acrylate latex films.

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.

Comparative assessment of poly (D,L-lactide-co-glycolide ...

African Journals Online (AJOL)

... are modified by CTAB and chitosan. Modification with chitosan yields PLGA nanoparticles with higher DNA adsorption and transfection with lower cytotoxicity. Keywords: Chitosan, cetyltrimethyl ammonium bromide (CTAB), Nanoparticle, Poly (D,L-lactide-coglycolide) PLGA, Plasmid DNA adsorption, Gene therapy ...

Effect of various surfactants (cationic, anionic and non-ionic) on the growth of Aspergillus parasiticus (NRRL 2999) in relation to aflatoxin production.

Science.gov (United States)

Tanuja, Kosuri; Hemalatha, K; Karuna, Rupula; Sashidhar Rao, B

2010-08-01

The effect of surfactants (two cationic, one anionic and three non-ionic) at 0.001, 0.01, 0.1 and 1.0 % concentrations on aflatoxin production, ergosterol content and sugar consumption by Aspergillus parasiticus (NRRL 2999) in YES liquid culture medium is reported. At 0.01% concentration, the cationic surfactants, cetyl dimethyl ammonium bromide (CDAB) and dodecyl trimethyl ammonium bromide (DTAB), and the anionic surfactant, sodium dodecyl sulfate (SDS), completely inhibited spore germination, while DTAB also inhibited the production of ergosterol and toxin (p lauryl ether (Brij-35) and ethoxylated p-tert-octylphenol (Triton X-100) delayed the spore germination up to day 5 at all concentrations and inhibited toxin and ergosterol production at 0.001% concentration. The affect was found to be dose-dependent from 0.001% to 1%, for Triton X-100 only. Positive correlation between ergosterol content and toxin production in the presence of different surfactants at various time periods (3, 5, 7, 9 and 12 days) was found. Tween-20 was most effective in inhibiting toxin production on day 7, when aflatoxin production was found to be maximal in control group. Sugar consumption was directly proportional to the ergosterol content, showing a significant correlation with aflatoxin production.

Cooperative Effects of Zwitterionic-Ionic Surfactant Mixtures on the Interfacial Water Structure Revealed by Sum Frequency Generation Vibrational Spectroscopy.

Science.gov (United States)

Pan, Xuecong; Yang, Fangyuan; Chen, Shunli; Zhu, Xuefeng; Wang, Chuanyi

2018-05-08

Cooperative effects of a series of equimolar binary zwitterionic-ionic surfactant mixtures on the interfacial water structure at the air-water interfaces have been studied by sum frequency generation vibrational spectroscopy (SFG-VS). For zwitterionic surfactant palmityl sulfobetaine (SNC 16 ), anionic surfactant sodium hexadecyl sulfate (SHS), and cationic surfactant cetyltrimethylammonium bromide (CTAB) with the same length of alkyl chain, significantly enhanced ordering of interfacial water molecules was observed for the zwitterionic-anionic surfactant mixtures SNC 16 -SHS, indicating that SNC 16 interacts more strongly with SHS than with CTAB because of the strong headgroup-headgroup electrostatic attraction for SNC 16 -SHS. Meanwhile, the SFG amplitude ratio of methyl and methylene symmetric stretching modes was used to verify the stronger interaction between SNC 16 and SHS. The conformational order indicator increased from 0.64 for SNC 16 to 7.17 for SNC 16 -SHS but only 0.94 for SNC 16 -CTAB. In addition, another anionic surfactant sodium dodecyl sulfate (SDS) was introduced to study the influence of chain-chain interaction. Decreased SFG amplitude of interfacial water molecules for SNC 16 -SDS was observed. Therefore, both the headgroup-headgroup electrostatic interaction and chain-chain van der Waals attractive interaction of the surfactants play an important role in enhancing the ordering of interfacial water molecules. The results provided experimental and theoretical bases for practical applications of the surfactants.

X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry characterization of aging effects on the mineral fibers treated with aminopropylsilane and quaternary ammonium compounds

DEFF Research Database (Denmark)

Zafar, Ashar; Schjødt-Thomsen, Jan; Sodhi, R.

2012-01-01

(PCA) was applied to the time-of-flight secondary ion mass spectrometry spectra, and an increase in the intensities of APS characteristic peaks were observed after aging. The observed increase in the signals of APS originates from underlying silanized fibers after the removal of the surfactant......X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry were used to investigate the aging effects on the aminopropylsilane (APS) and quaternary ammonium surfactant-treated mineral fibers. APS-coated mineral fiber samples were treated with cationic surfactant...

Surfactant protein D is proatherogenic in mice

DEFF Research Database (Denmark)

Sørensen, G. L.; Madsen, J.; Kejling, K.

2006-01-01

Surfactant protein D (SP-D) is an important innate immune defense molecule that mediates clearance of pathogens and modulates the inflammatory response. Moreover, SP-D is involved in lipid homeostasis, and pulmonary accumulation of phospholipids has previously been observed in SP-D-deficient (Spd...

Influence of clay, surfactant and presence of dispersant in the non-aqueous fluids rheology

International Nuclear Information System (INIS)

Gomes, N.L.; Guedes, I.C.; Menezes, R.R.; Campos, L.F.A.; Ferreira, H.S.

2012-01-01

The bentonite clay used as a thickening agent in production of non-aqueous fluids and can not be used without a prior treatment to their organic surfaces become hydrophobic. These treated clays are called organoclays, and are usually obtained by adding, in aqueous solution, a quaternary ammonium salt. This work makes a detailed study of the variables involved in the dispersion of the bentonite clays in organophilization process, as well, the type of clay, type of surfactant and the presence of dispersant. It was observed this study that the process variables involved in the dispersion of the clays and organophilization, observed through characterization, have low influence on the peaks related to interplanar basal distance caused by the incorporation of the surfactant and bentonite clays been influential the type of clay and surfactant and the presence of sodium as dispersant agent, on the rheological properties. (author)

Ammonium (E-3-(4-hydroxy-3-methoxyphenylprop-2-enoate monohydrate

Directory of Open Access Journals (Sweden)

Li-Cai Zhu

2010-11-01

Full Text Available In structure of the title compound ammonium ferulate monohydrate, NH4+·C10H9O4−·H2O, O—H...O and N—H...O hydrogen bonds link the ammonium cations, ferulate anions and water molecules into a three-dimensional array. The ferulate anion is approximately planar, with a maximum deviation of 0.307 (2 Å.

Comparative Effects of MMT Clay Modified with Two Different Cationic Surfactants on the Thermal and Rheological Properties of Polypropylene Nanocomposites

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Meshal Al-Samhan

2017-01-01

Full Text Available Polypropylene montmorillonite (MMT nanocomposites were prepared by melt blending using two different organoclays modified with imidazolium and alkylammonium surfactants. The imidazolium and ammonium modified organoclays were characterized by the FTIR and SEM analysis. The effect of organic clay (MMT on the physical properties of polypropylene was evaluated, thermal and rheological properties with different filler weight percentage. Differential scanning calorimetric results showed that imidazolium modified clay (IMMT exhibits low melting temperature compared to the ammonium modified clay (AMMT. The crystallinity analysis showed that crystallization improved in all nanocomposites irrespective of surface modification; the thermogravimetric analysis showed that the imidazolium modified polymer composites are more thermally stable than conventional ammonium modified composites. The Transmission Electron Microscopy (TEM analyses indicated that the PP-IMMT composites displayed exfoliated morphologies compared with the intercalated structure in PP-AMMT, and the rheological analysis at 180°C showed an enhancement in the viscoelastic properties as the clay concentration increases. The melt viscosity, crossover modulus, and relaxation times were comparable for both the surface modified composites with two different cations. The imidazolium based surfactant was found to be an effective organic modification for MMT to prepare thermally stable PP/MMT nanocomposites.

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.

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.)

Structure of DNA-Cationic Surfactant Complexes at Hydrophobically Modified and Hydrophilic Silica Surfaces as Revealed by Neutron Reflectometry

DEFF Research Database (Denmark)

Cardenas Gomez, Marite; Wacklin, Hanna; Campbell, Richard A.

2011-01-01

with dodecyltrimethylammonium bromide (DTAB) and hexadecyltrimethylammonium bromide (CTAB) on hydrophobic surfaces, where we show that DNA molecules are located on top of a self-assembled surfactant monolayer, with the thickness of the DNA layer and the surfactant DNA ratio determined by the surface coverage of the underlying...... interfacial structures, a higher concentration in relation to its cmc is required for the more soluble DTAB surfactant with a shorter alkyl chain than for CTAB. Our results suggest that the DNA Molecules Will spontaneously form a relatively dense, thin layer on top of a surfactant monolayer (hydrophobic...... surface) or a layer of admicelles (hydrophilic surface) as long as the surface concentration of surfactant is great enough to ensure a high interfacial-charge density. These findings have implications for bioanalytical and nanotechnology applications, which require the deposition of DNA layers with well...

Oxidative Pressure Leaching of Silver from Flotation Concentrates with Ammonium Thiocyanate Solution

Science.gov (United States)

Yang, Sheng-Hai; Yang, Jian-Guang; Liu, Wei; Chen, Geng-Tao; Tang, Mo-Tang; Qiu, Guan-Zhou

2010-02-01

The thermodynamics and technologies of the selective pressure leaching of silver from flotation concentrates were investigated in an ammonium thiocyanate medium. Thermodynamic analyses, which include silver solubility in NH4SCN solution and Eh-pH diagrams of the Me-MeS-NH4SCN-H2O system at 25 °C, were discussed. The effects of several factors, such as temperature, leaching time, oxidant, pH value, flotation concentrates concentration, surfactant concentration, and so on, on the extraction percentages of silver and zinc were investigated. The following optimal leaching conditions were obtained: NH4SCN concentration 1.5 M, lignin concentration 0.5 g/L, Fe3+ concentration 2 g/L, flotation concentrates addition 200 g/L, and oxygen pressure 1.2 MPa at 130 °C for 3 hours. Under these optimum conditions, the average extraction percentage of silver exceeded 94 pct, whereas the average extraction percentage of zinc was less than 3 pct. Only 7 pct of ammonium thiocyanate was consumed after 4 cycles, which indicated that ammonium thiocyanate hardly was oxidized under these oxidative pressure leaching conditions.

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.

Thermodynamics on the micellization of various pure and mixed surfactants: Effects of head- and tail-groups

International Nuclear Information System (INIS)

Lee, Nam-Min; Lee, Byung-Hwan

2016-01-01

Highlights: • The values of critical micelle concentration of various pure and mixed surfactants are measured. • Thermodynamic parameters’ values are calculated to analyze the effects of head- and tail-groups on the micellization. • All the thermodynamic parameters’ values are decreasing with the increase of temperature. • The thermodynamic parameters’ values are depending severely on the chain length of alkyl group. - Abstract: The values of critical micelle concentration (CMC) for the micellization of various pure and mixed surfactants are determined by the UV–Vis spectrophotometric method. And the effects of temperature on the CMC values have been measured and thermodynamic parameters’ values are calculated to analyse the effects of head- and tail-groups on the micellization of surfactant molecules. The results show that the values of ΔG"o are negative and those of ΔS"o are positive for the micellization of all the surfactants within the measured temperature range. But the values of ΔH"o are positive or negative, depending on the kinds of surfactants. All these thermodynamic parameters’ values are decreasing together with the increase of temperature for all the surfactants. And these thermodynamic parameters’ values are depending severely on the chain length of alkyl group also as much as on the head-groups of surfactant molecules.

Biocompatible Amphiphilic Hydrogel-Solid Dimer Particles as Colloidal Surfactants.

Science.gov (United States)

Chen, Dong; Amstad, Esther; Zhao, Chun-Xia; Cai, Liheng; Fan, Jing; Chen, Qiushui; Hai, Mingtan; Koehler, Stephan; Zhang, Huidan; Liang, Fuxin; Yang, Zhenzhong; Weitz, David A

2017-12-26

Emulsions of two immiscible liquids can slowly coalesce over time when stabilized by surfactant molecules. Pickering emulsions stabilized by colloidal particles can be much more stable. Here, we fabricate biocompatible amphiphilic dimer particles using a hydrogel, a strongly hydrophilic material, and achieve large contrast in the wetting properties of the two bulbs, resulting in enhanced stabilization of emulsions. We generate monodisperse single emulsions of alginate and shellac solution in oil using a flow-focusing microfluidics device. Shellac precipitates from water and forms a solid bulb at the periphery of the droplet when the emulsion is exposed to acid. Molecular interactions result in amphiphilic dimer particles that consist of two joined bulbs: one hydrogel bulb of alginate in water and the other hydrophobic bulb of shellac. Alginate in the hydrogel compartment can be cross-linked using calcium cations to obtain stable particles. Analogous to surfactant molecules at the interface, the resultant amphiphilic particles stand at the water/oil interface with the hydrogel bulb submerged in water and the hydrophobic bulb in oil and are thus able to stabilize both water-in-oil and oil-in-water emulsions, making these amphiphilic hydrogel-solid particles ideal colloidal surfactants for various applications.

[Effect of 60Co gamma-irradiation on dilute aqueous solutions of surfactants].

Science.gov (United States)

Sawai, T; Shimokowa, T; Miki, Y; Oseko, K; Sawai, T

1978-01-01

Present work deals with the effects of gamma irradiation from 60Co gamma-ray source upon aqueous solutions of three kinds of surfactants. When dilute aqueous solutions of sodium dodecyl sulfate (SDS, anionic), cethyl trimethyl ammonium chloride (CTAC, cationic), and polyoxyethylene lauryl ether (POE, non-ionic) were irradiated with gamma-rays at a room remperature, the residual concentration, products, surface tension, and forming power were examined by colorimetric method, IR spectrophotometric method, gaschromatography, Ross-Miles method, and Traube's stalagnometer etc.. These surfactants were decomposed by the irradiation and thus the surface tension increased and the forming power, on the contrary, decreased with dose. Radiation chemical yields (G-value) of the degradation were about 1 for the solutions of SDS and CTAC, and about 0.3 for the POE solution. From the experimental results, it was found that following chemical reactions seem to occur followed by the radiolysis of water; a) bond cleavage of ester for SDS, of CN for CTAC, and of oxyethylene for POE, b) hydrogen abstraction from the surfactants, c) production of CO bond in the presence of dissolved oxygen.

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.

The adsorption of alkyl-dimethyl-benzyl-ammonium chloride onto cotton nonwoven hydroentangled substrates at the solid-liquid interface is minimized by additive chemistries

Science.gov (United States)

Quaternary ammonium compounds, commonly referred to as quats, are cationic surfactants widely used as the active biocide ingredient for disposable disinfecting wipes. The cationic nature of quats results in a strong ionic interaction and adsorption onto wipes materials that have an anionic surface ...

Evaluation of the mechanism of skin enhancing surfactants on the biomembrane of shed snake skin.

Science.gov (United States)

Wonglertnirant, Nanthida; Ngawhirunpat, Tanasait; Kumpugdee-Vollrath, Mont

2012-01-01

The aim of the present work was to investigate the effects of different surfactants at various concentrations as a skin penetration enhancer through the biomembrane of the shed skin of Naja kaouthia. Additionally, the enhancer mechanism(s) of each class of surfactants were evaluated using physical characterization techniques, such as scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and small and wide angle X-ray scattering (SWAXS). Our results showed that skin permeability increased with increasing concentrations of surfactants and the degree of increase was higher for the model hydrophilic permeant, deuterium dioxide (D(2)O), than the lipophilic permeant, ketoprofen (KP). Ionic surfactants, sodium lauryl sulfate (SLS) and cetyl trimethyl ammonium bromide (CTAB), demonstrated higher enhancement ability than the polyoxyethylene (20) sorbitan mono-oleate (Tween 80) non-ionic surfactant, which was consistent with the results from physical characterization studies. Increasing amounts of permeated drug resulted in an increase in membrane interactions. From our observations, it can be assumed that SLS and CTAB can be localized inside the biomembrane and thereby enhance drug permeation mainly through interactions with intercellular lipids in the stratum corneum (SC) and the creation of a perturbed microenvironment among lipid alkyl chains and polar head groups.

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)

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 60Co gamma-ray irradiation on dilute aqueous solutions of surfactants

International Nuclear Information System (INIS)

Sawai, Teruko; Shimokawa, Toshinari; Miki, Yasushi; Oseko, Koichi; Sawai, Takeshi

1978-01-01

Present work deals with the effects of gamma irradiation from 60 Co γ-ray source upon aqueous solutions of three kinds of surfactants. When dilute aqueous solutions of sodium dodecyl sulfate (SDS, anionic), cethyl trimethyl ammonium chloride (CTAC, cationic), and polyoxyethylene lauryl ether (POE, non-ionic) were irradiated with γ-rays at a room temperature, the residual concentration, products, surface tension, and forming power were examined by colorimetric method, IR spectrophotometric method, gaschromatography, Ross-Miles method, and Traube's stalagmometer etc. These surfactants were decomposed by the irradiation and thus the surface tension increased and the forming power, on the contrary, decreased with dose. Radiation chemical yields (G-value) of the degradation were about 1 for the solutions of SDS and CTAC, and about 0.3 for the POE solution. From the experimental results, it was found that following chemical reactions seem to occur followed by the radiolysis of water: a) bond cleavage of ester for SDS, of CN for CTAC, and of oxyethylene for POE, b) hydrogen abstraction from the surfactants, c) production of CO bond in the presence of dissolved oxygen. (auth.)

The determination of the irritancy potential of surfactants using various methods of assessment.

Science.gov (United States)

Ciuchta, H P; Dodd, K T

1978-01-01

Several animal irritancy test methods whose criteria include sensory response, pain/discomfort or tissue damage were evaluated as to their ability to assess relative irritancy potential of the following surfactants: sodium lauryl polyether (12) sulfate (SLES), Miranol C2M (MC2M), Miranol MHT (MMHT), sodium coco methyl tauride (SCMT), triethanolamine lauryl sulfate (TEALS), ammonium lauryl sulfate (ALS) and sodium lauryl sulfate (SLS). Data from the mouse upper respiratory tract and mouse writhing tests indicated that SLES, MC2M and MMHT were the least irritating and SLS, ALS and TEALS were the most irritating. The blepharospasm test did not lend itself to this type of evaluation because sequential instillation of the surfactants produced eye anesthesia. Data from the Draize eye test indicated that SLES was the least irritating while MC2M was slightly more irritating. All other surfactants were equally irritating. The Draize skin test results showed that SLES again was the least irritating at all concentrations tested and that SLS and ALS along with TEALS and SCMT were the most irritating.

Green synthesis and characterization of cuprous oxide nanoparticles in presence of a bio-surfactant

Science.gov (United States)

Behera, M.; Giri, G.

2014-12-01

Herein, we report a facile green synthesis of Cu2O nanoparticles (NPs) using copper sulfate as precursor salt and hydrazine hydrate as reducing agent in presence of bio-surfactant (i.e. leaves extract of arka — a perennial shrub) at 60 to 70 °C in an aqueous medium. A broad band centered at 460 nm in absorption spectrum reveals the formation of surfactant stabilized Cu2O NPs. X-ray diffraction pattern of the surfactant stabilized NPs suggests the formation of only Cu2O phase in assistance of a bio-surfactant with the crystallite size of ˜8 nm. A negative zeta potential of -12 mV at 8.0 pH in surfactant stabilized Cu2O NPs hints non-bonding electron transfer from O-atom of saponin to the surface of NP. Red-shift in the vibrational band (Cu-O stretching) of Cu2O from 637 cm-1 to 640 cm-1 in presence of bio-surfactant suggests an interfacial interaction between NPs and O-atoms of -OH groups of saponin present in the plant (i.e. Calotropis gigantean) extract. From X-ray photoelectron spectroscopy spectra, a decrease in binding energy of both 2p3/2 and 2p1/2 bands in Cu2O with saponin molecules as compared to bulk Cu atom reveals a charge transfer interaction between NP and saponin surfactant molecules. Transmission electron microscopy images show crystalline nature of Cu2O NPs with an fcc lattice.

The Effect of a Rapid Heating Rate, Mechanical Vibration and Surfactant Chemistry on the Structure–Property Relationships of Epoxy/Clay Nanocomposites

Directory of Open Access Journals (Sweden)

Kevin Magniez

2013-08-01

Full Text Available The role of processing conditions and intercalant chemistry in montmorillonite clays on the dispersion, morphology and mechanical properties of two epoxy/clay nanocomposite systems was investigated in this paper. This work highlights the importance of employing complementary techniques (X-ray diffraction, small angle X-ray scattering, optical microscopy and transmission electron microscopy to correlate nanomorphology to macroscale properties. Materials were prepared using an out of autoclave manufacturing process equipped to generate rapid heating rates and mechanical vibration. The results suggested that the quaternary ammonium surfactant on C30B clay reacted with the epoxy during cure, while the primary ammonium surfactant (I.30E catalysed the polymerisation reaction. These effects led to important differences in nanocomposite clay morphologies. The use of mechanical vibration at 4 Hz prior to matrix gelation was found to facilitate clay dispersion and to reduce the area fraction of I.30E clay agglomerates in addition to increasing flexural strength by over 40%.

The Effect of a Rapid Heating Rate, Mechanical Vibration and Surfactant Chemistry on the Structure–Property Relationships of Epoxy/Clay Nanocomposites

Science.gov (United States)

Nuhiji, Betime; Attard, Darren; Thorogood, Gordon; Hanley, Tracey; Magniez, Kevin; Bungur, Jenny; Fox, Bronwyn

2013-01-01

The role of processing conditions and intercalant chemistry in montmorillonite clays on the dispersion, morphology and mechanical properties of two epoxy/clay nanocomposite systems was investigated in this paper. This work highlights the importance of employing complementary techniques (X-ray diffraction, small angle X-ray scattering, optical microscopy and transmission electron microscopy) to correlate nanomorphology to macroscale properties. Materials were prepared using an out of autoclave manufacturing process equipped to generate rapid heating rates and mechanical vibration. The results suggested that the quaternary ammonium surfactant on C30B clay reacted with the epoxy during cure, while the primary ammonium surfactant (I.30E) catalysed the polymerisation reaction. These effects led to important differences in nanocomposite clay morphologies. The use of mechanical vibration at 4 Hz prior to matrix gelation was found to facilitate clay dispersion and to reduce the area fraction of I.30E clay agglomerates in addition to increasing flexural strength by over 40%. PMID:28811457

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.

Rheological Properties of Hydrophobically Associative Copolymers Prepared in a Mixed Micellar Method Based on Methacryloxyethyl-dimethyl Cetyl Ammonium Chloride as Surfmer

Directory of Open Access Journals (Sweden)

Rui Liu

2014-01-01

Full Text Available A novel cationic surfmer, methacryloxyethyl-dimethyl cetyl ammonium chloride (DMDCC, is synthesized. The micellar properties, including critical micelle concentration and aggregation number, of DMDCC-SDS mixed micelle system are studied using conductivity measurement and a steady-state fluorescence technique. A series of water-soluble associative copolymers with acrylamide and DMDCC are prepared using the mixed micellar polymerization. Compared to conventional micellar polymerization, this new method could not only reasonably adjust the length of the hydrophobic microblock, that is, NH, but also sharply reduce the amount of surfactant. Their rheological properties related to hydrophobic microblock and stickers are studied by the combination of steady flow and linear viscoelasticity experiments. The results indicate that both the hydrophobic content and, especially the length of the hydrophobic microblock are the dominating factors effecting the intermolecular hydrophobic association. The presence of salt influences the dynamics of copolymers, resulting in the variation of solution characters. Viscosity measurement indicates that mixed micelles between the copolymer chain and SDS molecules serving as junction bridges for transitional network remarkably enhance the viscosity. Moreover, the microscopic structures of copolymers at different experimental conditions are conducted by ESEM. This method gives us an insight into the preparation of hydrophobically associative water-soluble copolymers by cationic surfmer-anionic surfactant mixed micellar polymerization with good performance.

Exfoliation of clays in poly(dimethylsiloxane) rubber using an unexpected couple: a silicone surfactant and water.

Science.gov (United States)

Labruyère, Céline; Monteverde, Fabien; Alexandre, Michaël; Dubois, Philippe

2009-04-01

Poly(dimethylsiloxane) (PDMS)/montmorillonite (MMT) composites have been prepared using a newly synthesized omega-ammonium functionalized poly(dimethylsiloxane) compatibilizer coupled with a dispersion technique in water. The organoclay containing the new siloxane surfactant was characterized by TGA and XRD. For the first time, a nanoscopic dispersion of MMT nanoplatelets in the PDMS composite cured by hydrosilylation and a good compatibility between clay layers and matrix were obtained. The beneficial effect of both the surfactant and the water onto clay nanoplatelet dispersion was evaluated by different microscopy techniques and by measuring different properties such as the viscosity of the uncured PDMS/MMT nanodispersions, and the swelling rate and Young's modulus of the cured PDMS/MMT nanocomposites.

Surfactant-free microemulsion electrokinetic chromatography (SF-MEEKC) with UV and MS detection - a novel approach for the separation and ESI-MS detection of neutral compounds.

Science.gov (United States)

Mohorič, Urška; Beutner, Andrea; Krickl, Sebastian; Touraud, Didier; Kunz, Werner; Matysik, Frank-Michael

2016-12-01

Microemulsion electrokinetic chromatography (MEEKC) is a powerful tool to separate neutral species based on differences in their hydrophobic and hydrophilic properties. However, as a major drawback the conventionally used SDS based microemulsions are not compatible with electrospray ionization mass spectrometry (ESI-MS). In this work, a surfactant-free microemulsion (SFME) consisting of water, ethanol, and 1-octanol is used for surfactant-free microemulsion electrokinetic chromatography (SF-MEEKC). Ammonium acetate was added to the SFME enabling electrophoretic separations. The stability of SFMEs containing ammonium acetate was investigated using small-angle X-ray scattering and dynamic light scattering. A method for the separation of a model system of hydrophobic and hydrophilic neutral vitamins, namely the vitamins B 2 and D 3 , and the cationic vitamin B 1 was developed using UV/VIS detection. The influence of the ammonium acetate concentration on the separation performance was studied in detail. The method was characterized concerning reproducibility of migration times and peak areas and concerning the linearity of the calibration data. Furthermore, SF-MEEKC was coupled to ESI-MS investigating the compatibility between SFMEs and the ESI process. The signal intensities of ESI-MS measurements of the model analytes were comparable for SFMEs and aqueous systems. Finally, the vitamin D 3 content of a drug treating vitamin D 3 deficiency was determined by SF-MEEKC coupled to ESI-MS using 25-hydroxycholecalciferol as an internal standard. Graphical abstract The concept of surfactant-free microemulsion electrokinetic chromatography coupled to electrospray ionization mass spectrometry.

Single charging events on colloidal particles in a nonpolar liquid with surfactant

Science.gov (United States)

Schreuer, Caspar; Vandewiele, Stijn; Brans, Toon; Strubbe, Filip; Neyts, Kristiaan; Beunis, Filip

2018-01-01

Electrical charging of colloidal particles in nonpolar liquids due to surfactant additives is investigated intensively, motivated by its importance in a variety of applications. Most methods rely on average electrophoretic mobility measurements of many particles, which provide only indirect information on the charging mechanism. In the present work, we present a method that allows us to obtain direct information on the charging mechanism, by measuring the charge fluctuations on individual particles with a precision higher than the elementary charge using optical trapping electrophoresis. We demonstrate the capabilities of the method by studying the influence of added surfactant OLOA 11000 on the charging of single colloidal PMMA particles in dodecane. The particle charge and the frequency of charging events are investigated both below and above the critical micelle concentration (CMC) and with or without applying a DC offset voltage. It is found that at least two separate charging mechanisms are present below the critical micelle concentration. One mechanism is a process where the particle is stripped from negatively charged ionic molecules. An increase in the charging frequency with increased surfactant concentration suggests a second mechanism that involves single surfactant molecules. Above the CMC, neutral inverse micelles can also be involved in the charging process.

Surfactant loss control in chemical flooding: Spectroscopic and calorimetric study of adsorption and precipitation on reservoir minerals. Annual report, September 30, 1992--September 30, 1993

Energy Technology Data Exchange (ETDEWEB)

Somasundaran, P.

1994-07-01

The aim of this research project is to investigate mechanisms underlying adsorption and surface precipitation of flooding surfactants on reservoir minerals. Effects of surfactant structure, surfactant combinations, various inorganic and polymeric species, and solids mineralogy will be determined. A multi-pronged approach consisting of micro & nano spectroscopy, microcalorimetry, electrokinetics, surface tension and wettability; is used in this study. The results obtained should help in controlling surfactant loss in chemical flooding and in developing optimum structures and conditions for efficient chemical flooding processes. During the first year of this three year contract, adsorption of single surfactants and select surfactant mixtures was studied at the solid-liquid and gas-liquid interfaces. Surfactants studied include alkyl xylene sulfonates, polyethoxylated alkyl phenols, octaethylene glycol mono n-decyl ether, and tetradecyl trimethyl ammonium chloride. Adsorption of surfactant mixtures of varying composition was also investigated. The microstructure of the adsorbed layer was characterized using fluorescence spectroscopy. Changes interfacial properties such as wettability, electrokinetics and stability of reservoir minerals were correlated with the amount of reagent adsorbed. Strong effects of the structure of the surfactant and position of functional groups were revealed.

Spontaneous vesicle phase formation by pseudogemini surfactants in aqueous solutions.

Science.gov (United States)

Sun, Nan; Shi, Lijuan; Lu, Fei; Xie, Shuting; Zheng, Liqiang

2014-08-14

The phase behavior of a kind of pseudogemini surfactant in aqueous solutions, formed by the mixture of sodium dodecyl benzene sulfonate (SDBS) and butane-1,4-bis (methylimidazolium bromide) ([mim-C4-mim]Br2) or butane-1,4-bis(methylpyrrolidinium bromide) ([mpy-C4-mpy]Br2) in a molar ratio of 2 : 1, is reported in the present work. When [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 is mixed with SDBS in aqueous solutions, one cationic [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 molecule "bridges" two SDBS molecules by noncovalent interactions (e.g. electrostatic, π-π stacking, and σ-π interactions), behaving like a pseudogemini surfactant. Vesicles can be formed by this kind of pseudogemini surfactant, determined by freeze-fracture transmission electron microscopy (FF-TEM) or cryogenic-transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS). The mixed system of sodium dodecyl sulfate (SDS) with [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 was also constructed, and only micelles were observed. We infer that a pseudogemini surfactant is formed under the synergic effect of electrostatic, π-π stacking, and σ-π interactions in the SDBS/[mim-C4-mim]Br2/H2O system, while electrostatic attraction and hydrophobic interactions may provide the directional force for vesicle formation in the SDBS/[mpy-C4-mpy]Br2/H2O system.

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.

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)

Adsorption of β-casein-surfactant mixed layers at the air-water interface evaluated by interfacial rheology.

Science.gov (United States)

Maestro, Armando; Kotsmar, Csaba; Javadi, Aliyar; Miller, Reinhard; Ortega, Francisco; Rubio, Ramón G

2012-04-26

This work presents a detailed study of the dilational viscoelastic moduli of the adsorption layers of the milk protein β-casein (BCS) and a surfactant at the liquid/air interface, over a broad frequency range. Two complementary techniques have been used: a drop profile tensiometry technique and an excited capillary wave method, ECW. Two different surfactants were studied: the nonionic dodecyldimethylphosphine oxide (C12DMPO) and the cationic dodecyltrimethylammonium bromide (DoTAB). The interfacial dilational elasticity and viscosity are very sensitive to the composition of protein-surfactant mixed adsorption layers at the air/water interface. Two different dynamic processes have been observed for the two systems studied, whose characteristic frequencies are close to 0.01 and 100 Hz. In both systems, the surface elasticity was found to show a maximum when plotted versus the surfactant concentration. However, at frequencies above 50 Hz the surface elasticity of BCS + C12DMPO is higher than the one of the aqueous BCS solution over most of the surfactant concentration range, whereas for the BCS + DoTAB it is smaller for high surfactant concentrations and higher at low concentrations. The BCS-surfactant interaction modifies the BCS random coil structure via electrostatic and/or hydrophobic interactions, leading to a competitive adsorption of the BCS-surfactant complexes with the free, unbound surfactant molecules. Increasing the surfactant concentration decreases the adsorbed proteins. However, the BCS molecules are rather strongly bound to the interface due to their large adsorption energy. The results have been fitted to the model proposed by C. Kotsmar et al. ( J. Phys. Chem. B 2009 , 113 , 103 ). Even though the model describes well the concentration dependence of the limiting elasticity, it does not properly describe its frequency dependence.

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.

Effect of protein-surfactant interactions on aggregation of β-lactoglobulin.

Science.gov (United States)

Hansted, Jon G; Wejse, Peter L; Bertelsen, Hans; Otzen, Daniel E

2011-05-01

The milk protein β-lactoglobulin (βLG) dominates the properties of whey aggregates in food products. Here we use spectroscopic and calorimetric techniques to elucidate how anionic, cationic and non-ionic surfactants interact with bovine βLG and modulate its heat-induced aggregation. Alkyl trimethyl ammonium chlorides (xTAC) strongly promote aggregation, while sodium alkyl sulfates (SxS) and alkyl maltopyranosides (xM) reduce aggregation. Sodium dodecyl sulfate (SDS) binds to non-aggregated βLG in several steps, but reduction of aggregation was associated with the first binding step, which occurs far below the critical micelle concentration. In contrast, micellar concentrations of xMs are required to reduce aggregation. The ranking order for reduction of aggregation (normalized to their tendency to self-associate) was C10-C12>C8>C14 for SxS and C8>C10>C12>C14>C16 for xM. xTAC promote aggregation in the same ranking order as xM reduce it. We conclude that SxS reduce aggregation by stabilizing the protein's ligand-bound state (the melting temperature t(m) increases by up to 10°C) and altering its charge potential. xM monomers also stabilize the protein's ligand-bound state (increasing t(m) up to 6°C) but in the absence of charged head groups this is not sufficient by itself to prevent aggregation. Although micelles of both anionic and non-ionic surfactants destabilize βLG, they also solubilize unfolded protein monomers, leaving them unavailable for protein-protein association and thus inhibiting aggregation. Cationic surfactants promote aggregation by a combination of destabilization and charge neutralization. The food compatible surfactant sodium dodecanoate also inhibited aggregation well below the cmc, suggesting that surfactants may be a practical way to modulate whey protein properties. Copyright © 2011 Elsevier B.V. All rights reserved.

Constraint and flow: Poiseuille shear response of a surfactant ...

Indian Academy of Sciences (India)

Abstract. To minimize their free energy in aqueous solution, surfactant molecules self-assemble to form some basic morphologies – globular micelles, highly extended thead- like micelles and membrane bilayers – which themselves order to display a rich variety of mesophase symmetries and properties. In membrane ...

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.

Synthesis of Au and Au/Cu alloy nanoparticles on multiwalled carbon nanotubes by using microwave irradiation

International Nuclear Information System (INIS)

Rangari, Vijaya K.; Dey, Sanchita; Jeelani, Shaik

2010-01-01

Gold nanoparticles and gold-copper alloy nanoparticles were synthesized by reduction of chloroauric acid (HAuCl_4.xH_2O) and co-reduction of chloroauric acid (HAuCl_4.xH_2O) and Copper(II) acetate [(CH_3COO)_2Cu.H_2O] by ethylene glycol through microwave irradiation technique. In this reaction ethylene glycol used as a solvent and also reducing agent. The cetyltrimethyl ammonium bromide (CTAB) used as surfactant. Au nanoparticles and Au-Cu nanoparticles on the surface of multiwalled carbon nanotube also produced by using same procedure. The XRD analysis confirmed the formation of Au and Au-Cu alloy nanoparticles on multiwalled carbon nanotubes(CNTs). The morphology and size of the particles were examined by the transmission electron microscopy. The EDS analysis on individual particles confirmed that the presence of two metals in a particle in case of alloy nanoparticle. The results presented here show that a variety of well defined metal and metal alloy nanoparticles can be produced by using the microwave polyol process with in a short period of time. (author)

Simultaneous quantification of poly-dispersed anionic, amphoteric and nonionic surfactants in simulated wastewater samples using C18 high-performance liquid chromatography-quadrupole ion-trap mass spectrometry

Science.gov (United States)

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

2005-01-01

This paper describes the development of a guantitative method for direct and simultaneous determination of three frequently encountered surfactants, amphoteric (cocoamphoacetate, CAA), anionic (sodium laureth sulfate, SLES), and nonionic (alcohol ethoxylate, AE) using a reversed-phase C18 HPLC coupled with an ESI ion-trap mass spectrometer (MS). Chemical composition, ionization characteristics and fragmentation pathways of the surfactants are presented. Positive ESI was effective for all three surfactants in agueous methanol buffered with ammonium acetate. The method enables rapid determinations in small sample volumes containing inorganic salts (up to 3.5 g L(-1)) and multiple classes of surfactants with high specificity by applying surfactant specific tandem mass spectrometric strategies. It has dynamic linear ranges of 2-60, 1.5-40, 0.8-56 mg L(-1) with R2 egual or greater than 0.999, 0.98 and 0.999 (10 microL injection) for CAA, SLES, and AE, respectively.

Dynamics of Surfactant Clustering at Interfaces and Its Influence on the Interfacial Tension: Atomistic Simulation of a Sodium Hexadecane-Benzene Sulfonate-Tetradecane-Water System.

Science.gov (United States)

Paredes, Ricardo; Fariñas-Sánchez, Ana Isabel; Medina-Rodrı Guez, Bryan; Samaniego, Samantha; Aray, Yosslen; Álvarez, Luis Javier

2018-03-06

The process of equilibration of the tetradecane-water interface in the presence of sodium hexadecane-benzene sulfonate is studied using intensive atomistic molecular dynamics simulations. Starting as an initial point with all of the surfactants at the interface, it is obtained that the equilibration time of the interface (several microseconds) is orders of magnitude higher than previously reported simulated times. There is strong evidence that this slow equilibration process is due to the aggregation of surfactants molecules on the interface. To determine this fact, temporal evolution of interfacial tension and interfacial formation energy are studied and their temporal variations are correlated with cluster formation. To study cluster evolution, the mean cluster size and the probability that a molecule of surfactant chosen at random is free are obtained as a function of time. Cluster size distribution is estimated, and it is observed that some of the molecules remain free, whereas the rest agglomerate. Additionally, the temporal evolution of the interfacial thickness and the structure of the surfactant molecules on the interface are studied. It is observed how this structure depends on whether the molecules agglomerate or not.

Dyes adsorption blue vegetable and blue watercolor by natural zeolites modified with surfactants;Adsorcion de colorantes azul vegetal y azul acuarela por zeolitas naturales modificadas con surfactantes

Energy Technology Data Exchange (ETDEWEB)

Jardon S, C. C.; Olguin G, M. T. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Diaz N, M. C., E-mail: teresa.olguin@inin.gob.m [Instituto Tecnologico de Toluca, Av. Instituto Tecnologico s/n, Ex-Rancho la Virgen, 52140 Metepec, Estado de Mexico (Mexico)

2009-07-01

In this work was carried out the dyes removal blue vegetable and blue watercolor of aqueous solutions, to 20 C, at different times and using a zeolite mineral of Parral (Chihuahua, Mexico) modified with hexadecyl trimethyl ammonium bromide or dodecyl trimethyl ammonium bromide. The zeolite was characterized before and after of its adaptation with NaCl and later with HDTMABr and DTMABr. For the materials characterization were used the scanning electron microscopy of high vacuum; elementary microanalysis by X-ray spectroscopy of dispersed energy and X-ray diffraction techniques. It was found that the surfactant type absorbed in the zeolite material influences on the adsorption process of the blue dye. Likewise, the chemical structure between the vegetable blue dye and the blue watercolor, determines the efficiency of the color removal of the water, by the zeolites modified with the surfactants. (Author)

Interactions between fluorinated cationic guar gum and surfactants in the dilute and semi-dilute solutions.

Science.gov (United States)

Wang, Chen; Li, Xiaorui; Li, Peizhi; Niu, Yuhua

2014-01-01

The interactions between the fluorinated cationic guar gum (FCGG) and ionic surfactants including cetyl trimethyl ammonium bromide (CTAB) and sodium lauryl sulfate (SDS) were studied by light scattering, fluorescence spectroscopy, UV-spectrophotometer, (19)F NMR and dynamic rheometer, respectively. The FCGG is prepared with cationic guar gum, isophorone diisocyanate and 2,2,3,4,4,4-hexafluoro-1-butanol. The results show that, with the addition of the surfactants, the stretching degree of the FCGG chains is increased in the FCGG/CTAB solutions, while the dramatical shrinking of FCGG chain, the phase separation and the re-stretched macromolecules appear successively because of the electricity neutralization reaction in the FCGG/SDS system. The mixed hydrophobic domains in all solutions will be reinforced and then dismantled. The solution elasticity shows up the maximum value accordingly. The surfactants can be embedded in the micro-domains and then hinder the fluorinated segmental motions. The interactions between FCGG and SDS are much stronger than those between FCGG and CTAB. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

Synthesis of Zn/Co/Fe-layered double hydroxide nanowires with controllable morphology in a water-in-oil microemulsion

Energy Technology Data Exchange (ETDEWEB)

Wu Hongyu; Jiao Qingze [School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing, 100081 (China); Zhao Yun, E-mail: zhaoyun@bit.edu.cn [School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing, 100081 (China); Huang Silu; Li Xuefei; Liu Hongbo; Zhou Mingji [School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing, 100081 (China)

2010-02-15

The Zn/Co/Fe-layered double hydroxide nanowires were synthesized via a reverse microemulsion method by using cetyltrimethyl ammonium bromide (CTAB) /n-hexane/n-hexanol/water as Soft-Template. ZnSO{sub 4}, CoSO{sub 4}, Fe{sub 2}(SO{sub 4}){sub 3} and urea were used as raw materials. The influence of reaction temperature, time, urea concentration and Cn (molar ratio of cetyltrimethyl ammonium bromide to water) on the structure and morphology of Zn/Co/Fe-layered double hydroxides was investigated. The samples were characterized using Transmission Electron Microscopy (TEM), Inductively Coupled Plasma (ICP), X-ray Diffraction (XRD) and Infrared Absorption Spectrum (IR). The results indicate that higher temperature is beneficial to the formation of layered double hydroxides, but particles apart from nanowires could be produced if temperature is up to 120 deg. C. By varying the temperature, reaction time, urea concentration and Cn, we got the optimum conditions of synthesizing uniform Zn/Co/Fe-layered double hydroxide nanowires: 100 deg. C, more than 12 h, Cn: 30-33, urea concentration: 0.3 M.

Theoretical modeling of cationic surfactant aggregation at the silica/aqueous solution interface: Effects of pH and ionic strength

NARCIS (Netherlands)

Drach, M.; Andrzejewska, A.; Narkiewicz-Michalek, J.; Rudzinski, W.; Koopal, L.K.

2002-01-01

A theory of ionic surfactant aggregation on oppositely charged surfaces is presented. In the proposed model the adsorbed phase is considered as a mixture of singly dispersed surfactant molecules, monolayered and bilayered aggregates of various sizes and the ions of simple electrolyte added to the

Ceria nanocubic-ultrasonication assisted dispersive liquid-liquid microextraction coupled with matrix assisted laser desorption/ionization mass spectrometry for pathogenic bacteria analysis.

Science.gov (United States)

Abdelhamid, Hani Nasser; Bhaisare, Mukesh L; Wu, Hui-Fen

2014-03-01

A new ceria (CeO2) nanocubic modified surfactant is used as the basis of a novel nano-based microextraction technique for highly sensitive detection of pathogenic bacteria (Pseudomonas aeruginosa and Staphylococcus aureus). The technique uses ultrasound enhanced surfactant-assisted dispersive liquid-liquid microextraction (UESA-DLLME) with and without ceria (CeO2) followed by matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). In order to achieve high separation efficiency, we investigated the influential parameters, including extraction time of ultrasonication, type and volume of the extraction solvent and surfactant. Among various surfactants, the cationic surfactants can selectively offer better extraction efficiency on bacteria analysis than that of the anionic surfactants due to the negative charges of bacteria cell membranes. Extractions of the bacteria lysate from aqueous samples via UESA-DLLME-MALDI-MS were successfully achieved by using cetyltrimethyl ammonium bromide (CTAB, 10.0 µL, 1.0×10(-3) M) as surfactants in chlorobenzene (10.0 µL) and chloroform (10.0 µL) as the optimal extracting solvent for P. aeruginosa and S. aureus, respectively. Ceria nanocubic was synthesized, and functionalized with CTAB (CeO2@CTAB) and then characterized using transmission electron microscopy (TEM) and optical spectroscopy (UV and FTIR). CeO2@CTAB demonstrates high extraction efficiency, improve peaks ionization, and enhance resolution. The prime reasons for these improvements are due to the large surface area of nanoparticles, and its absorption that coincides with the wavelength of MALDI laser (337 nm, N2 laser). CeO2@CTAB-based microextraction offers lowest detectable concentrations tenfold lower than that of without nanoceria. The present approach has been successfully applied to detect pathogenic bacteria at low concentrations of 10(4)-10(5) cfu/mL (without ceria) and at 10(3)-10(4) cfu/mL (with ceria) from bacteria suspensions. Finally, the

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

Solid-phase extraction sorbent consisting of alkyltrimethylammonium surfactants immobilized onto strong cation-exchange polystyrene resin.

Science.gov (United States)

Reid, Kendra R; Kennedy, Lonnie J; Crick, Eric W; Conte, Eric D

2002-10-25

Presented is a solid-phase extraction sorbent material composed of cationic alkyltrimethylammonium surfactants attached to a strong cation-exchange resin via ion-exchange. The original hydrophilic cation-exchange resin is made hydrophobic by covering the surface with alkyl chains from the hydrophobic portion of the surfactant. The sorbent material now has a better ability to extract hydrophobic molecules from aqueous samples. The entire stationary phase (alkyltrimethylammonium surfactant) is removed along with the analyte during the elution step. The elution step requires a mild elution solvent consisting of 0.25 M Mg2+ in a 50% 2-propanol solution. The main advantage of using a removable stationary phase is that traditionally utilized toxic elution solvents such as methylene chloride, which are necessary to efficiently release strongly hydrophobic species from SPE stationary phases, may now be avoided. Also, the final extract is directly compatible with reversed-phase liquid chromatography. The performance of this procedure is presented using pyrene as a test molecule.

Analysis of polyethoxylated surfactants in microemulsion-oil-water systems III. Fractionation and partitioning of polyethoxylated alcohol surfactants

International Nuclear Information System (INIS)

Marquez, N.; Bravo, B.; Ysambertt, F.; Chavez, G.; Subero, N.; Salager, J.L.

2002-01-01

Oligomer distribution of polyethoxylated alcohol and polyethoxylated nonylphenol surfactants is studied by normal and reverse-phase high performance liquid chromatography (HPLC). A RP8 column is able to efficiently separate these surfactants according to their alkyl chain (lipophilic) group, while silica and amino columns separate them according to their polyether chain length (hydrophilic group). Polyethoxylated alcohol and polyethoxylated nonylphenol oligomers selectively partition between the microemulsion-oil-water phases of a Winsor III system. Partitioning of these oligomers was analyzed by HPLC with RI detection. The logarithm of the partition coefficient between the water and oil linearly increases with the number of ethylene oxide groups per molecule of oligomer. For a same ethoxylation degree, the partition coefficient of a polyethoxylated tridecanol is found to be higher than the one of the corresponding nonylphenol specie. On the other hand, a polyethoxylated nonylphenol exhibits a higher solubilization than the matching polyethoxylated alcohol

PLUNC: a multifunctional surfactant of the airways

OpenAIRE

Bartlett, Jennifer; Gakhar, Lokesh; Penterman, Jon; Singh, Pradeep; Mallampalli, Rama K.; Porter, Edith; McCray, Paul B.

2011-01-01

PLUNC (palate, lung and nasal epithelium clone) protein is an abundant secretory product of epithelia throughout the mammalian conducting airways. Despite its homology with the innate immune defence molecules BPI (bactericidal/permeability-increasing protein) and LBP (lipopolysaccharide-binding protein), it has been difficult to define the functions of PLUNC. Based on its marked hydrophobicity and expression pattern, we hypothesized that PLUNC is an airway surfactant. We found that purified r...

Genetic diversity among natural populations of Ottelia acuminata ...

African Journals Online (AJOL)

PRECIOUS

2009-11-16

Nov 16, 2009 ... A total number of 120 O. acuminate accessions were analyzed, by amplification of their DNAs with 15 ... mortar and pestle. The powder was transferred to a 25 ml sterile. Falcon tube with 10 ml of CTAB buffer. The extraction buffer con- sisted of 2% (w/v) CTAB (cetyltrimethyl ammonium bromide,. Sigma), 1.5 ...

Preparatory of X zeolite (faujasite) with surfactant hexa decyl trimethyl ammonium bromide (HMDTA) for adsorption of organic compounds

International Nuclear Information System (INIS)

Gonzalez R, V.

2003-01-01

The water represents one of the most valuable natural resources for the alive beings, since it is the essential component of the alive matter. Also, it is fundamental part of our planet, since is an indispensable element for the integral development of the same one. The demographic growth, the human being's activities and the industrial growth, he/she brings as consequence an increase in the use of the water and the generation of residual waters that successively contaminate the hydrological basins, becoming an environmental problem urgent. The contamination of the water with compound such as phenol and benzene, it is a problem that it requires the search of solutions, since it is of compound not very biodegradable, able to accumulate through the food chains and very toxic to the alive beings that they enter in contact with them (Tolgyessy, 1993). In the human beings it can take place damages in liver and kidney, the Agency of Protection to the Atmosphere of the United States (EPA) it considers that the exhibition for benzene is related with the leukemia, it is also considered as a carcinogen substance. Of the methods that are used for the treatment of polluted waters, it highlights the use of adsorber and one of them is the zeolites, since they are broadly used in those separation processes. The zeolites is crystalline aluminosilicates, they are characterized for to have a big superficial area and for their great capacity of exchange cationic, due to it the process of adsorption depends on these two characteristics, since to the modified being superficially for surfactants cationic it originates an enriched layer of carbon organic, which has the capacity to remove pollutants of the water. The present work outlines as objective to carry out the superficial modification of zeolite X using hexa decyl trimethyl ammonium bromide (HMDTA-Br) to different concentrations, with the purpose of making it useful in the removal of pollutants organic, present in watery solution

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.

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.

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 loss control in chemical flooding spectroscopic and calorimetric study of adsorption and precipitation on reservoir minerals. Annual report, September 30, 1993--September 30, 1994

Energy Technology Data Exchange (ETDEWEB)

Somasundaran, P.

1995-06-01

The aim of this project is to elucidate the mechanisms underlying adsorption and surface precipitation of flooding surfactants on reservoir minerals. Effect of surfactant structure, surfactant combinations, other inorganic and polymeric species is being studied. A multi-pronged approach consisting of micro and nano spectroscopy, microcalorimetry, electrokinetics, surface tension and wettability is used to achieve the goals. The results of this study should help in controlling surfactant loss in chemical flooding and also in developing optimum structures and conditions for efficient chemical flooding processes. During the second year of this three year contract, adsorption/desorption of single surfactants and select surfactant mixtures on alumina and silica was studied. Surfactants studied include the anionic sodium dodecyl sulfate (SDS), cationic tetradecyl trimethyl ammonium chloride (TTAC), nonionic pentadecylethoxylated nonyl phenol (NP-15) and the nonionic octaethylene glycol n-dodecyl ether (C{sub 12}EO{sub 8}) of varying hydrocarbon chain length. The microstructure of the adsorbed layer in terms of micropolarity and aggregation numbers was probed using fluorescence spectroscopy. Changes of microstructure upon dilution (desorption) were also studied. Presence of the nonionic surfactant in the mixed aggregate led to shielding of the charge of the ionic surfactant which in-turn promoted aggregation but reduced electrostatic attraction between the charged surfactant and the mineral surface. Strong consequences of surfactant interactions in solution upon adsorption as well as correlations between monomer concentrations in mixtures and adsorption were revealed.

Surfactant loss control in chemical flooding spectroscopic and calorimetric study of adsorption and precipitation on reservoir minerals. Annual report, September 30, 1992--September 30 1995

Energy Technology Data Exchange (ETDEWEB)

Casteel, J. [Bartlesville Project Office, OK (United States)

1996-07-01

The aim of this research project was to investigate mechanisms governing adsorption and surface precipitation of flooding surfactants on reservoir minerals. Effects of surfactant structure, surfactant combinations, various inorganic and polymeric species, and solids mineralogy have been determined. A multi-pronged approach consisting of micro & nano spectroscopy, electrokinetics, surface tension and wettability is used in this study. The results obtained should help in controlling surfactant loss in chemical flooding and in developing optimum structures and conditions for efficient chemical flooding processes. During the three years contract period, adsorption of single surfactants and select surfactant mixtures was studied at the solid-liquid and gas-liquid interfaces. Alkyl xylene sulfonates, polyethoxylated alkyl phenols, octaethylene glycol mono n-decyl ether, and tetradecyl trimethyl ammonium chloride were the surfactants studied. Adsorption of surfactant mixtures of varying composition was also investigated. The microstructure of the adsorbed layer was characterized using fluorescence spectroscopy. Changes in interfacial properties such as wettability, electrokinetics and stability of reservoir minerals were correlated with the amounts of reagent adsorbed. Strong effects of the structure of the surfactant and position of functional groups were revealed. Changes of microstructure upon dilution (desorption) were also studied. Presence of the nonionic surfactants in mixed aggregate leads to shielding of the charge of ionic surfactants which in turn promotes aggregation but reduced electrostatic attraction between the charged surfactant and the mineral surface. Strong consequences of surfactant interactions in solution on adsorption as well as correlations between monomer concentration in mixtures and adsorption were revealed.

Surfactant-induced skin irritation and skin repair. Evaluation of the acute human irritation model by noninvasive techniques.

Science.gov (United States)

Wilhelm, K P; Freitag, G; Wolff, H H

1994-06-01

Although the induction of irritant dermatitis by surfactants has been extensively studied in recent years, our understanding of the repair phase of irritant dermatitis is limited. We investigated qualitative and quantitative differences in surfactant-induced irritant skin reactions from short-term exposure to three structurally different surfactants. Sodium lauryl sulfate (SLS), dodecyl trimethyl ammonium bromide (DTAB), and potassium soap were the model irritants. Surfactant solutions (0.5%) were applied for 24 hours to the volar aspect of the forearm of 11 volunteers. Irritant reactions were assessed until complete healing was indicated by visual assessment and by various aspects of skin function, that is, transepidermal water loss (TEWL), erythema (skin color reflectance), and stratum that is, transepidermal water loss (TEWL), erythema (skin color reflectance), and stratum corneum hydration (electrical capacitance). SLS and DTAB induced similar degrees of erythema, whereas SLS induced significantly higher TEWL increase. Although both erythema and TEWL were highest 1 hour after exposure to surfactants, skin dryness was a symptom with delayed onset, justifying the long observation period in this study. Minimum hydration values were measured as late as 7 days after surfactant exposure. Dryness was significantly more pronounced in areas exposed to SLS than in areas exposed to DTAB. Complete repair of the irritant reaction induced by either SLS or DTAB was achieved 17 days after surfactant exposure. Stratum corneum hydration was the last feature to return to baseline values. Potassium soap did not significantly influence any skin function. We emphasize the importance of extended periods needed before a patient with irritant contact dermatitis can be reexposed to irritant substances. The evaluation of the irritation potential of diverse surfactants depended significantly on the feature (erythema vs hydration and TEWL) measured.

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

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

Respiratory and Systemic Effects of LASSBio596 Plus Surfactant in Experimental Acute Respiratory Distress Syndrome

Directory of Open Access Journals (Sweden)

Johnatas Dutra Silva

2016-02-01

Full Text Available Background/Aims: Exogenous surfactant has been proposed as adjunctive therapy for acute respiratory distress syndrome (ARDS, but it is inactivated by different factors present in the alveolar space. We hypothesized that co-administration of LASSBio596, a molecule with significant anti-inflammatory properties, and exogenous surfactant could reduce lung inflammation, thus enabling the surfactant to reduce edema and improve lung function, in experimental ARDS. Methods: ARDS was induced by cecal ligation and puncture surgery in BALB/c mice. A sham-operated group was used as control (CTRL. After surgery (6 hours, CTRL and ARDS animals were assigned to receive: (1 sterile saline solution; (2 LASSBio596; (3 exogenous surfactant or (4 LASSBio596 plus exogenous surfactant (n = 22/group. Results: Regardless of exogenous surfactant administration, LASSBio596 improved survival rate and reduced collagen fiber content, total number of cells and neutrophils in PLF and blood, cell apoptosis, protein content in BALF, and urea and creatinine levels. LASSBio596 plus surfactant yielded all of the aforementioned beneficial effects, as well as increased BALF lipid content and reduced surface tension. Conclusion: LASSBio596 exhibited major anti-inflammatory and anti-fibrogenic effects in experimental sepsis-induced ARDS. Its association with surfactant may provide further advantages, potentially by reducing surface tension.

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.

[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.

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.

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

Directory of Open Access Journals (Sweden)

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.

Energy-mediated versus ammonium-regulated gene expression in the obligate ammonia-oxidizing bacterium, Nitrosococcus oceani

Directory of Open Access Journals (Sweden)

Lisa Y Stein

2013-09-01

Full Text Available Ammonia serves as the source of energy and reductant and as a signaling molecule that regulates gene expression in obligate ammonia-oxidizing chemolithotrophic microorganisms. The gammaproteobacterium, Nitrosococcus oceani, was the first obligate ammonia-oxidizer isolated from seawater and is one of the model systems for ammonia chemolithotrophy. We compared global transcriptional responses to ammonium and the catabolic intermediate, hydroxylamine, in ammonium-starved and non-starved cultures of N. oceani to discriminate transcriptional effects of ammonium from a change in overall energy and redox status upon catabolite availability. The most highly expressed genes from ammonium- or hydroxylamine-treated relative to starved cells are implicated in catabolic electron flow, carbon fixation, nitrogen assimilation, ribosome structure and stress tolerance. Catabolic inventory-encoding genes, including electron flow-terminating Complexes IV, FoF1 ATPase, transporters, and transcriptional regulators were among the most highly expressed genes in cells exposed only to ammonium relative to starved cells, although the differences compared to steady-state transcript levels were less pronounced. Reduction in steady-state mRNA levels from hydroxylamine-treated relative to starved-cells were less than five-fold. In contrast, several transcripts from ammonium-treated relative to starved cells were significantly less abundant including those for forward Complex I and a gene cluster of cytochrome c encoding proteins. Identified uneven steady-state transcript levels of co-expressed clustered genes support previously reported differential regulation at the levels of transcription and transcript stability. Our results differentiated between rapid regulation of core genes upon a change in cellular redox status versus those responsive to ammonium as a signaling molecule in N. oceani, both confirming and extending our knowledge of metabolic modules involved in ammonia

Molecular dynamics of surfactant protein C

DEFF Research Database (Denmark)

Ramírez, Eunice; Santana, Alberto; Cruz, Anthony

2006-01-01

Surfactant protein C (SP-C) is a membrane-associated protein essential for normal respiration. It has been found that the alpha-helix form of SP-C can undergo, under certain conditions, a transformation from an alpha-helix to a beta-strand conformation that closely resembles amyloid fibrils, which...... are possible contributors to the pathogenesis of pulmonary alveolar proteinosis. Molecular dynamics simulations using the NAMD2 package were performed for systems containing from one to seven SP-C molecules to study their behavior in water. The results of our simulations show that unfolding of the protein...

Host-Guest Interaction between Corona[n]arene and Bisquaternary Ammonium Derivatives for Fabricating Supra-Amphiphile.

Science.gov (United States)

Zeng, Lingda; Guo, Qing-Hui; Feng, Yuanning; Xu, Jiang-Fei; Wei, Yuhan; Li, Zhibo; Wang, Mei-Xiang; Zhang, Xi

2017-06-13

The interactions between a host, water-soluble corona[n]arene (S6-CAP), and a series of guests, bisquaternary ammonium derivatives (CnDAs), in water, were investigated. The host and guest can form 1:1 host-guest complex. Their binding constants decrease as the alkyl length of CnDAs increases, which can be tunable ranging from 10 3 to 10 6 M -1 . The binding processes are mainly entropy-driven, while the enthalpy changes also play an important role in enhancing the host-guest interactions. In addition, a supra-amphiphile was fabricated with S6-CAP and a normal surfactant bearing bisquaternary ammonium (C4R). The S6-CAP·C4R complex forms micellar aggregates in water, and the system possesses better assembling activity and dilution stability than its building block C4R. This study enriches the families of supra-amphiphiles with a new architecture, and employing such a supra-amphiphile in biofunctional materials is highly anticipated.

Study of conformation and dynamic of surfactant molecules in graphite oxide via NMR

Energy Technology Data Exchange (ETDEWEB)

Ai, X.Q. [Jiangsu Second Normal University, College of Physics and Electronic Engineering, Nanjing (China); Ma, L.G. [Nanjing Xiaozhuang University, School of Electronic Engineering, Nanjing (China)

2016-08-15

The conformation and dynamic of surfactant in graphite oxide (GO) was investigated by solid-state {sup 13}C magic-angle-spinning NMR and {sup 1}H-{sup 13}C cross-polarization/magic-angle-spinning NMR spectra. The conformation ordering of the alkyl chains in the confined system shows strong dependence on its orientation. While the alkyl chains parallel to the GO layer in lateral monolayer arrangement are in gauche conformation in addition to a small amount of all-trans conformation, those with orientation radiating away from the GO in paraffin bilayer arrangement is in all-trans conformation in addition to some gauche conformation even though high-order diffraction peaks appears. NMR results suggest that the least mobile segment is located at the GO-surfactant interface corresponding to the N-methylene group. Further from it, the mobility of the alkyl chain increases. The terminal methyl and N-methyl carbon groups have the highest mobile. The chains in all-trans conformational state are characterized as more rigid than chains with gauche conformation; each segment of the confined alkyl chains with the lateral monolayer arrangement exhibits less mobility as compared to that with the paraffin bilayer arrangement. (orig.)

Hydration Structure of the Quaternary Ammonium Cations

KAUST Repository

Babiaczyk, Wojtek Iwo

2010-11-25

Two indicators of the hydropathicity of small solutes are introduced and tested by molecular dynamics simulations. These indicators are defined as probabilities of the orientation of water molecules\\' dipoles and hydrogen bond vectors, conditional on a generalized distance from the solute suitable for arbitrarily shaped molecules. Using conditional probabilities, it is possible to distinguish features of the distributions in close proximity of the solute. These regions contain the most significant information on the hydration structure but cannot be adequately represented by using, as is usually done, joint distance-angle probability densities. Our calculations show that using our indicators a relative hydropathicity scale for the interesting test set of the quaternary ammonium cations can be roughly determined. © 2010 American Chemical Society.

Elastic properties of surfactant monolayers at liquid-liquid interfaces: A molecular dynamics study

DEFF Research Database (Denmark)

Laradji, Mohamed; Mouritsen, Ole G.

2000-01-01

Using a simple molecular model based on the Lennard-Jones potential, we systematically study the elastic properties of liquid-liquid interfaces containing surfactant molecules by means of extensive and large-scale molecular dynamics simulations. The main elastic constants of the interface, corres...

Preparation of Nano Activated γ-Alumina ( with Surfactant and Surface Characterization

Directory of Open Access Journals (Sweden)

Enas Sameer AL-Khawaja

2016-09-01

Full Text Available This paper deals with the preparation of Alumina by sol-gel technique through the hydrolysis of aluminum ion mixed with the glucose as a surfactant and converting it to gel by ammonium hydroxide in aqueous media. The resulting sol composed of particle is draying to become a transparent gel. The freshly prepared gel is heated at 700°C for 2hrs to obtain alumina ( particles. The obtained particles are found to be γ-alumina particles with high porosity, Their characteristics are determined by LPSA, XRD, SEM, TEM and BET techniques. The results show that the particles are pure alumina, nano-sized=20nm, spherical shape, high surface area=210 /gm.

Exciplex emission from amphiphilic polysilanes bearing ammonium moieties

International Nuclear Information System (INIS)

Yamaki, T.; Nakashiba, Y.; Asai, K.; Ishigure, K.; Shibata, H.

1997-01-01

We were the first to observe two emission bands in the visible region for some kinds of ammonium-type amphiphilic polysilanes both in solutions and in thin films. One, a broad emission band at 400-500 nm not due to a σ * →σ transition, was observed only for methylphenylsilane-based polymer solutions. The appearance of this low-energy emission is reasonably explained by considering the intramolecular exciplex formation between a Si-conjugated main chain and an ammonium site in the same monomer unit. The other, an emission band at the longer wavelength (around 560 nm), was found in the solvent-cast films where each molecule is randomly located, in addition to that observed for the solutions. This emission, which was not observed for the oriented LB films, is considered to originate from an intermolecular interaction. (orig.)

Treating ammonium-rich wastewater with sludge from water treatment plant to produce ammonium alum

Directory of Open Access Journals (Sweden)

Wen-Po Cheng

2016-03-01

Full Text Available This study applies a process to treat ammonium-rich wastewater using alum-generated sludge form water purification plant, and gain economic benefit by producing ammonium alum (Al(NH4(SO42·12H2O. The factors affecting production of ammonium alum include molar ratio of ammonium to aluminum concentration, sulfuric acid concentration, mixing speed, mixing time, standing time, and temperature. According to the equation for the ammonium removal reaction, the theoretical quantity of ammonium alum was calculated based on initial and final concentrations of ammonium. Then, the weight of ammonium alum crystal was divided by the theoretical weight to derive the recovery ratio. The optimum sludge and sulfuric acid dosage to treat about 17 g L−1 ammonium wastewater are 300 g L−1 and 100 mL L−1, respectively. The optimal dosage for wastewater is molar ratio of ammonium to aluminum of about 1 due to the aluminum dissolving in acidified wastewater. The ammonium removal efficiency is roughly 70% and the maximum recovery ratio for ammonium alum is 93% when the wastewater is mixed for 10 min at the mixing velocity gradient of 100 s−1. Ammonium alum production or ammonium removal can be enhanced by controlling the reaction at low temperatures.

Specific ion effects on the properties of cationic Gemini surfactant monolayers

International Nuclear Information System (INIS)

Alejo, T.; Merchan, M.D.; Velazquez, M.M.

2011-01-01

The effects of some anions of the Hofmeister series and different divalent cations of alkaline earth metals on the properties of Langmuir monolayers of the cationic Gemini surfactant ethyl-bis (dimethyl octadecylammonium bromide) have been investigated. Surface pressure and potential isotherms at the air-water interface were obtained on aqueous subphases containing sodium salts with several anions of the Hofmeister series (Cl - , NO 3 - , Br - , I - , ClO 4 - , and SCN - ). The influence of the investigated anions on the monolayer properties can be ordered according to the Hofmeister series with a change in the order between bromide and nitrate anions. On the other hand, for a given anion, the cation of the salt also influences the surface properties of the Langmuir films. The monolayers can be transferred onto mica by the Langmuir-Blodgett technique and then the Langmuir-Blodgett films were characterized by atomic force microscopy (AFM). The AFM images show that the molecules become more closely packed and nearly vertical to the surface when anions screen the electric charge of the surfactant molecules.

Specific ion effects on the properties of cationic Gemini surfactant monolayers

Energy Technology Data Exchange (ETDEWEB)

Alejo, T.; Merchan, M.D.; Velazquez, M.M., E-mail: mvsal@usal.es

2011-06-01

The effects of some anions of the Hofmeister series and different divalent cations of alkaline earth metals on the properties of Langmuir monolayers of the cationic Gemini surfactant ethyl-bis (dimethyl octadecylammonium bromide) have been investigated. Surface pressure and potential isotherms at the air-water interface were obtained on aqueous subphases containing sodium salts with several anions of the Hofmeister series (Cl{sup -}, NO{sub 3}{sup -}, Br{sup -}, I{sup -}, ClO{sub 4}{sup -}, and SCN{sup -}). The influence of the investigated anions on the monolayer properties can be ordered according to the Hofmeister series with a change in the order between bromide and nitrate anions. On the other hand, for a given anion, the cation of the salt also influences the surface properties of the Langmuir films. The monolayers can be transferred onto mica by the Langmuir-Blodgett technique and then the Langmuir-Blodgett films were characterized by atomic force microscopy (AFM). The AFM images show that the molecules become more closely packed and nearly vertical to the surface when anions screen the electric charge of the surfactant molecules.

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.)

Influence of ammonium nitrate on kinetics and mechanism of thermal decomposition of ammonium polyuranates

International Nuclear Information System (INIS)

Karelin, A.I.; Lobas, O.P.; Zhiganov, A.N.; Vasil'ev, K.F.; Zhiganova, A.A.

1988-01-01

The influence of ammonium nitrate on the mechanism and kinetics of dehydration and thermal decomposition of ammonium polyuranates was studied. An appreciable influence of the nitrate ion content in the samples of ammonium polyuranates on the development of thermal stability has been noted. The kinetic parameters of the thermal decomposition of ammonium polyuranates have been evaluated. A mechanism of the dehydration and thermal decomposition of ammonium polyuranates in the presence of ammonium nitrate has been proposed. It was shown that increase in the content of ammonium nitrate in the precipitate of ammonium polyuranates leads to a decrease in the specific surface of uranoso-uranic oxide

Solubility of ammonium metavanadate in ammonium carbonate and sodium bicarbonate solutions at 25 deg C

International Nuclear Information System (INIS)

Fedorov, P.I.; Andreev, V.K.; Slotvinskij-Sidak, N.P.

1978-01-01

Solubility at 25 deg C has been studied in the system ammonium metavanadate - sodium bicarbonate - water which is a stable section of the corresponding quaternary mutual system. In the eutonic point the content of ammonium metavanadate is 4.95% and of sodium bicarbonate 12.1%. The crystallization branch of ammonium metavanadate has been studied in the system ammonium metavanadate - ammonium carbonate - water at 25 deg C. Metavanadate solubility attains minimum (0.14%) at ammonium carbonate concentration 2.6%. Three sections have been studied of the quaternary system ammonium - metavanadate - ammonium carbonate - sodium bicarbonate-water at 25 deg C in the crystallization region of ammonium metavanadate at a ratio of sodium bicarbonate to ammonium carbonate 3:1, 1:1, and 1:3. A region of minimum solubility of ammonium metavanadate has been detected (0.1%)

Human salivary agglutinin binds to lung surfactant protein-D and is identical with scavenger receptor protein gp-340

DEFF Research Database (Denmark)

Ligtenberg, T J; Bikker, F J; Groenink, J

2001-01-01

bound in a similar way to Streptococcus mutans and surfactant protein-D. Histochemically, the distribution of gp-340 in the submandibular salivary glands was identical with the agglutinin distribution, as shown in a previous paper [Takano, Bogert, Malamud, Lally and Hand (1991) Anat. Rec. 230, 307......-318]. We conclude that agglutinin is identical with gp-340, and that this molecule interacts with S. mutans and surfactant protein-D....

Effects of the conjugation of whey proteins with gellan polysaccharides on surfactant-induced competitive displacement from the air-water interface.

Science.gov (United States)

Cai, B; Ikeda, S

2016-08-01

Whey proteins can be used to stabilize foams and emulsions against coalescence because of their ability to form viscoelastic films at the interface that resist film rupture on collision between colloidal particles. However, whey proteins are competitively displaced from the interface if small-molecule surfactants are added, leading to destabilization of the entire system. This is because surfactants are more effective in molecular packing at the interface, and they lower interfacial tension to a greater degree than whey proteins do, but their interfacial films are poor in viscoelasticity. We hypothesized that whey proteins would become more resistant to surfactant-induced competitive displacement if they were conjugated with network-forming polysaccharides. The protein moiety of the conjugate would be expected to enable its adsorption to the interface, and the polysaccharide moiety would be expected to form self-assembled networks, strengthening the interfacial film as a whole. In this study, whey proteins were conjugated with gellan polysaccharides using the Maillard reaction. Atomic force microscopy images of interfacial films formed by the whey protein-gellan conjugate at the air-water interface and transferred onto mica sheets using the Langmuir-Blodgett method revealed that gellan did form self-assembled networks at the interface and that interfacial films also contained a large number of unconjugated whey protein molecules. Following the addition of a small-molecule surfactant (Tween 20) to the sub-phase, surface pressure increased, indicating spontaneous adsorption of surfactants to the interface. Atomic force microscopy images showed decreases in interfacial area coverage by whey proteins as surface pressure increased. At a given surface pressure, the interfacial area coverage by whey protein-gellan conjugates was greater than coverage by unconjugated whey proteins, confirming that whey proteins became more resistant to surfactant-induced displacement after

Elevated ammonium levels

DEFF Research Database (Denmark)

Søgaard, Rikke; Novak, Ivana; MacAulay, Nanna

2012-01-01

was not enhanced. The ammonium-induced stimulation of EAAT3 increased with increasing extracellular pH, suggesting that the gaseous form NH(3) mediates the effect. An ammonium-induced intracellular alkalinization was excluded as the cause of the enhanced EAAT3 activity because 1) ammonium acidified the oocyte...

Influence of nonionic surfactants on the potentiometric response of hydrogen ion-selective polymeric membrane electrodes.

Science.gov (United States)

Espadas-Torre, C; Bakker, E; Barker, S; Meyerhoff, M E

1996-05-01

The influence of poly(ethylene oxide)-based nonionic surfactants (i.e., Triton X-100 and Brij 35) in the sample phase on the response properties of hydrogen ion-selective polymeric membrane electrodes containing mobile (lipophilic amines) or covalently bound (aminated-poly-(vinyl chloride)) hydrogen ion carriers is reported. In the presence of these nonionic surfactants, membrane electrode response toward interfering cation activity (e.g., Na+) in the sample phase is increased substantially and the pH measuring range shortened. The degree of cation interference for pH measurements is shown to correlate with the basicity of the hydrogen ion carrier doped within the membrane phase. The observed deterioration in selectivity arises from the partitioning of the surfactant into the membrane and concomitant extraction of metal cations by the surfactants in the organic phase. The effect of nonionic surfactants on pH electrodes prepared with aminated-PVC membranes is shown to be more complex, with additional large shifts in EMF values apparently arising from multidentate interactions between the surfactant molecules and the polymeric amine in the membrane, leading to a change in the apparent pKa values for the amine sites. The effects induced by nonionic surfactants on the EMF response function of hydrogen ion-selective polymeric membrane electrodes are modeled, and experimental results are shown to correlate well with theoretical predictions.

Adsorption Of Surfactants At the Water-Oil Interface By Short-Time Diffusion

Science.gov (United States)

Cortes-Estrada, Aldo; Ibarra-Bracamontes, Laura; Aguilar-Corona, Alicia; Viramontes-Gamboa, Gonzalo

2017-11-01

Surface tension is an important parameter for different industrial processes. The addition of surfactants can modify the interfacial tension between two fluids. As the surfactant molecules reach and are adsorbed at a fluid interface, the surface tension or interfacial tension is reduced until the interface is saturated. Dynamic Interfacial tension measurements were carried out using an optical tensiometer by the Pendant Drop technique at a room temperature of 25 °C for a period of 250 sec. A drop of surfactant solution was deposited and allowed to diffuse into a water-oil interface, and then the adsorption rate at the interface was calculated. Sodium Dodecyl Sulfate (SDS) was used as the surfactant, hexane and dodecane were tested as the oil phase. A linear decay in the interfacial tension was observed for the lower initial concentrations of the order of 0.0001 to 0.01 mM, and an exponential decay was observed for initial concentrations of the order of 0.1 to 1 mM. This study was supported by the Mexican Council of Science and Technology (CONACyT) and by the Scientific Research Coordination of the University of Michoacan in Mexico.

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

Science.gov (United States)

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

2011-09-20

The adsorption of the surface-active protein hydrophobin, HFBII, and the competitive adsorption of HFBII with the cationic, anionic, and nonionic surfactants hexadecyltrimethylammonium bromide, CTAB, sodium dodecyl sulfate, SDS, and hexaethylene monododecyl ether, C(12)E(6), has been studied using neutron reflectivity, NR. HFBII adsorbs strongly at the air-water interface to form a dense monolayer ∼30 Å thick, with a mean area per molecule of ∼400 Å(2) and a volume fraction of ∼0.7, for concentrations greater than 0.01 g/L, and the adsorption is independent of the solution pH. In competition with the conventional surfactants CTAB, SDS, and C(12)E(6) at pH 7, the HFBII adsorption totally dominates the surface for surfactant concentrations less than the critical micellar concentration, cmc. Above the cmc of the conventional surfactants, HFBII is displaced by the surfactant (CTAB, SDS, or C(12)E(6)). For C(12)E(6) this displacement is only partial, and some HFBII remains at the surface for concentrations greater than the C(12)E(6) cmc. At low pH (pH 3) the patterns of adsorption for HFBII/SDS and HFBII/C(12)E(6) are different. At concentrations just below the surfactant cmc there is now mixed HFBII/surfactant adsorption for both SDS and C(12)E(6). For the HFBII/SDS mixture the structure of the adsorbed layer is more complex in the region immediately below the SDS cmc, resulting from the HFBII/SDS complex formation at the interface. © 2011 American Chemical Society

Male reproductive system parameters in a two-generation reproduction study of ammonium perfluorooctanoate in rats and human relevance.

Science.gov (United States)

York, Raymond G; Kennedy, Gerald L; Olsen, Geary W; Butenhoff, John L

2010-04-30

Ammonium perfluorooctanoate (ammonium PFOA) is an industrial surfactant that has been used primarily as a processing aid in the manufacture of fluoropolymers. The environmental and metabolic stability of PFOA together with its presence in human blood and long elimination half-life have led to extensive toxicological studies in laboratory animals. Two recent publications based on observations from the Danish general population have reported: (1) a negative association between serum concentrations of PFOA in young adult males and their sperm counts and (2) a positive association among women with time to pregnancy. A two-generation reproduction study in rats was previously published (2004) in which no effects on functional reproduction were observed at doses up to 30mg ammonium PFOA/kg body weight. The article contained the simple statement: "In males, fertility was normal as were all sperm parameters". In order to place the recent human epidemiological data in perspective, herein we provide the detailed male reproductive parameters from that study, including sperm quality and testicular histopathology. Sperm parameters in rats from the two-generation study in all ammonium PFOA treatment groups were unaffected by treatment with ammonium PFOA. These observations reflected the normal fertility observations in these males. No evidence of altered testicular and sperm structure and function was observed in ammonium PFOA-treated rats whose mean group serum PFOA concentrations ranged up to approximately 50,000ng/mL. Given that median serum PFOA in the Danish cohorts was approximately 5ng/mL, it seems unlikely that concentrations observed in the general population, including those recently reported in Danish general population, could be associated causally with a real decrement in sperm number and quality.

Using Iron-Manganese Co-Oxide Filter Film to Remove Ammonium from Surface Water.

Science.gov (United States)

Zhang, Ruifeng; Huang, Tinglin; Wen, Gang; Chen, Yongpan; Cao, Xin; Zhang, Beibei

2017-07-19

An iron-manganese co-oxide filter film (MeO x ) has been proven to be a good catalyst for the chemical catalytic oxidation of ammonium in groundwater. Compared with groundwater, surface water is generally used more widely and has characteristics that make ammonium removal more difficult. In this study, MeO x was used to remove ammonium from surface water. It indicated that the average ammonium removal efficiency of MeO x was greater than 90%, even though the water quality changed dramatically and the water temperature was reduced to about 6-8 °C. Then, through inactivating microorganisms, it showed that the removal capability of MeO x included both biological (accounted for about 41.05%) and chemical catalytic oxidation and chemical catalytic oxidation (accounted for about 58.95%). The investigation of the characterizations suggested that MeO x was formed by abiotic ways and the main elements on the surface of MeO x were distributed homogenously. The analysis of the catalytic oxidation process indicated that ammonia nitrogen may interact with MeO x as both ammonia molecules and ammonium ions and the active species of O₂ were possibly • O and O₂ - .

Investigation of ammonium nitrate effect on kinetics and mechanism of thermal decomposition of ammonium polyuranates

International Nuclear Information System (INIS)

Karelin, A.I.; Lobas, O.P.; Zhiganov, A.N.; Vasil'ev, K.F.; Zhiganova, A.A.

1987-01-01

A study was made on ammonium nitrate effect on the mechanism and kinetics of dehydration and thermal decomposition of ammonium polyuranates. Sufficient effect of nitrate ion content in ammonium polyuranate samples on their thermal stability was noted. Kinetic parameters of thermal decomposition of ammonium polyuranates were evaluated. Mechanism of dehydration and thermal decomposition of ammonium polyuranates in the presence of ammonium nitrate was suggested. It was shown that increase of ammonium nitrate content in ammonium polyuranate precipitate resulted to reduction of the specific surface of prepared uranium mixed oxide

The photodegradation of trichloroethylene with or without the NAPL by UV irradiation in surfactant solutions

Energy Technology Data Exchange (ETDEWEB)

Jia Juncai [Department of Civil and Structural Engineering, Research Centre for Urban Environmental Technology and Management, Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Chu, W. [Department of Civil and Structural Engineering, Research Centre for Urban Environmental Technology and Management, Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)], E-mail: cewchu@polyu.edu.hk

2009-01-15

The photodegradation of trichloroethene (TCE) with or without nonaqueous phase liquids (NAPL) by ultraviolet irradiation in surfactant solutions was examined in this study. The photodecay of TCE was studied at monochromatic 254 nm UV lamps. The effects of the type of surfactants, initial surfactant concentrations, pH levels and NAPL concentrations were examined to explore the photodecay of TCE. All the photodegradation of TCE followed pseudo-first-order decay kinetics at various conditions. It was found that Brij 35 overdose and higher initial pH levels may retard or inhibit the photodecay of TCE, mainly due to protons, intermediate generation and change of surfactant structure in the processes. The optimal condition for TCE photodecay was suggested based on the analysis of kinetics data, from which the reaction mechanism of TCE in the presence of NAPL form was also studied. In general, the reactions of TCE in micellar solution and NAPL pool can be considered as independent pathways due to the low molecule diffusion between the two phases.

The photodegradation of trichloroethylene with or without the NAPL by UV irradiation in surfactant solutions

International Nuclear Information System (INIS)

Jia Juncai; Chu, W.

2009-01-01

The photodegradation of trichloroethene (TCE) with or without nonaqueous phase liquids (NAPL) by ultraviolet irradiation in surfactant solutions was examined in this study. The photodecay of TCE was studied at monochromatic 254 nm UV lamps. The effects of the type of surfactants, initial surfactant concentrations, pH levels and NAPL concentrations were examined to explore the photodecay of TCE. All the photodegradation of TCE followed pseudo-first-order decay kinetics at various conditions. It was found that Brij 35 overdose and higher initial pH levels may retard or inhibit the photodecay of TCE, mainly due to protons, intermediate generation and change of surfactant structure in the processes. The optimal condition for TCE photodecay was suggested based on the analysis of kinetics data, from which the reaction mechanism of TCE in the presence of NAPL form was also studied. In general, the reactions of TCE in micellar solution and NAPL pool can be considered as independent pathways due to the low molecule diffusion between the two phases

Desorption of hydrocarbon chains by association with ionic and nonionic surfactants under flow as a mechanism for enhanced oil recovery.

Science.gov (United States)

Terrón-Mejía, Ketzasmin A; López-Rendón, Roberto; Goicochea, Armando Gama

2017-08-29

The need to extract oil from wells where it is embedded on the surfaces of rocks has led to the development of new and improved enhanced oil recovery techniques. One of those is the injection of surfactants with water vapor, which promotes desorption of oil that can then be extracted using pumps, as the surfactants encapsulate the oil in foams. However, the mechanisms that lead to the optimal desorption of oil and the best type of surfactants to carry out desorption are not well known yet, which warrants the need to carry out basic research on this topic. In this work, we report non equilibrium dissipative particle dynamics simulations of model surfactants and oil molecules adsorbed on surfaces, with the purpose of studying the efficiency of the surfactants to desorb hydrocarbon chains, that are found adsorbed over flat surfaces. The model surfactants studied correspond to nonionic and cationic surfactants, and the hydrocarbon desorption is studied as a function of surfactant concentration under increasing Poiseuille flow. We obtain various hydrocarbon desorption isotherms for every model of surfactant proposed, under flow. Nonionic surfactants are found to be the most effective to desorb oil and the mechanisms that lead to this phenomenon are presented and discussed.

Stable perovskite solar cells by surface modification with surfactant molecules

Energy Technology Data Exchange (ETDEWEB)

Holanda, Matheus Serra de; Nogueira, Ana Flavia, E-mail: mholandabsb@outlook.com [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Quimica

2016-07-01

Full text: Surface modification on organic-inorganic perovskite films using dodecylammonium chloride was done to improve the stability of the material over the air moisture, which is considered extremely harmful to these materials and complicates their application on solar cell technology. Perovskite CH{sub 3}NH{sub 3}PbI{sub 3} was prepared by single step method using a solution containing PbI{sub 2} and CH{sub 3}NH{sub 3}I on DMF:DMSO (2:1) on a concentration of 0.88 mol L{sup -1}. The film was deposited over a planar film of TiO{sub 2}, previously deposited over FTO glass, by using spin-casting method. 25 μL of the solution was spread over the substrate which was turned at 4000 RPM for 45 s. In the last 10 s, 800 μL of monochlorobenzene was dropped. The film was submitted to a thermal treatment so the conversion of the perovskite could be completed. After the thermal treatment, the modifier was spin coated over the perovskite film from 5 and 10 mg mL{sup -1} solutions of the dodecylammonium chloride in chloroform. The perovskite films were characterized by SEM, XRD and UV-Vis spectroscopy. SEM images have shown that the modifiers agglomerate and they cover the perovskite film, forming a protection layer. XRD and UV-Vis carried out after the film preparation, 7 and 15 days after the deposition. The first results show that the protection layer is able to avoid degradation of the perovskite film. Photovoltaic devices were prepared by depositing Spiro-OMeTAD as HTM layer and gold as electrode. It was observed that the increase on the thickness of the surfactant layer causes a decrease on the short-circuit current density (JSC), which is expected since is starts to act like an insulating layer. This effect is also the cause of the reduction of the fill factor (FF). More experiments need to be carried out to improve the solar cells devices, but the present data has shown the potential of the method developed, which uses easy access surfactants and a simple

Stable perovskite solar cells by surface modification with surfactant molecules

International Nuclear Information System (INIS)

Holanda, Matheus Serra de; Nogueira, Ana Flavia

2016-01-01

Full text: Surface modification on organic-inorganic perovskite films using dodecylammonium chloride was done to improve the stability of the material over the air moisture, which is considered extremely harmful to these materials and complicates their application on solar cell technology. Perovskite CH 3 NH 3 PbI 3 was prepared by single step method using a solution containing PbI 2 and CH 3 NH 3 I on DMF:DMSO (2:1) on a concentration of 0.88 mol L -1 . The film was deposited over a planar film of TiO 2 , previously deposited over FTO glass, by using spin-casting method. 25 μL of the solution was spread over the substrate which was turned at 4000 RPM for 45 s. In the last 10 s, 800 μL of monochlorobenzene was dropped. The film was submitted to a thermal treatment so the conversion of the perovskite could be completed. After the thermal treatment, the modifier was spin coated over the perovskite film from 5 and 10 mg mL -1 solutions of the dodecylammonium chloride in chloroform. The perovskite films were characterized by SEM, XRD and UV-Vis spectroscopy. SEM images have shown that the modifiers agglomerate and they cover the perovskite film, forming a protection layer. XRD and UV-Vis carried out after the film preparation, 7 and 15 days after the deposition. The first results show that the protection layer is able to avoid degradation of the perovskite film. Photovoltaic devices were prepared by depositing Spiro-OMeTAD as HTM layer and gold as electrode. It was observed that the increase on the thickness of the surfactant layer causes a decrease on the short-circuit current density (JSC), which is expected since is starts to act like an insulating layer. This effect is also the cause of the reduction of the fill factor (FF). More experiments need to be carried out to improve the solar cells devices, but the present data has shown the potential of the method developed, which uses easy access surfactants and a simple preparation method to improve the stability of

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

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.

Adsorption studies of a water soluble dye, Reactive Red MF-3B, using sonication-surfactant-modified attapulgite clay

International Nuclear Information System (INIS)

Huang Jianhua; Liu Yuanfa; Jin Qingzhe; Wang Xingguo; Yang Jun

2007-01-01

The removal of water-soluble Reactive Red MF-3B from aqueous media by sonication-surfactant-modified attapulgite clay was studied in a batch system. The surfactant used was octodecyl trimethyl ammonium chloride (OTMAC). Adsorbent characterizations were investigated using X-ray diffraction, infrared spectroscopy, and surface area analysis. The effects of pH, contact time, initial solute concentration, adsorbent dose, and temperature on the adsorption of Reactive Red MF-3B onto modified clay were investigated. On the basis of kinetic studies, specific rate constants involved in the processes were calculated and second-order adsorption kinetics was observed in the case. Film diffusion was found to be the rate-limiting step. Reactive Red MF-3B adsorption was found to increase with increase temperature. The Reactive Red MF-3B equilibrium adsorption data were fitted to Freundlich and Langmuir isotherm models, the former being found to provide the better fit of the experimental data. Thermodynamic parameters were calculated. From the results it can be concluded that the surfactant-modified clay could be a good adsorbent for treating Reactive Red MF-3B-contaminated waters

Adsorption of hydroxamate siderophores and EDTA on goethite in the presence of the surfactant sodium dodecyl sulfate

Directory of Open Access Journals (Sweden)

Xu Jide

2009-06-01

Full Text Available Abstract Siderophore-promoted iron acquisition by microorganisms usually occurs in the presence of other organic molecules, including biosurfactants. We have investigated the influence of the anionic surfactant sodium dodecyl sulfate (SDS on the adsorption of the siderophores DFOB (cationic and DFOD (neutral and the ligand EDTA (anionic onto goethite (α-FeOOH at pH 6. We also studied the adsorption of the corresponding 1:1 Fe(III-ligand complexes, which are products of the dissolution process. Adsorption of the two free siderophores increased in a similar fashion with increasing SDS concentration, despite their difference in molecule charge. In contrast, SDS had little effect on the adsorption of EDTA. Adsorption of the Fe-DFOB and Fe-DFOD complexes also increased with increasing SDS concentrations, while adsorption of Fe-EDTA decreased. Our results suggest that hydrophobic interactions between adsorbed surfactants and siderophores are more important than electrostatic interactions. However, for strongly hydrophilic molecules, such as EDTA and its iron complex, the influence of SDS on their adsorption seems to depend on their tendency to form inner-sphere or outer-sphere surface complexes. Our results demonstrate that surfactants have a strong influence on the adsorption of siderophores to Fe oxides, which has important implications for siderophore-promoted dissolution of iron oxides and biological iron acquisition.

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.

Pulmonary haptoglobin (pHp) is part of the surfactant system in the human lung.

Science.gov (United States)

Abdullah, Mahdi; Goldmann, Torsten

2012-11-20

Since the existence of pHp was demonstrated, it has been shown that this molecule and its receptor CD163 are regulated by different stimuli. Furthermore, a comparably fast secretion of pHp was described as well as the immuno-stimulatory effects. The intention of this study was to elucidate the role of pHp in the human lungs further. Here we show, by means of confocal microscopy and immune-electron-microscopy, a clear co-localization of pHp with surfactant protein-B in lamellar bodies of alveolar epithelial cells type II. These results are underlined by immunohistochemical stainings in differently fixed human lung tissues, which show pHp in vesicular and released form. The images of the released form resemble the intended position of surfactant in the human alveolus. pHp is secreted by Alveolar epithelial cells type II as previously shown. Moreover, pHp is co-localized with Surfactant protein-B. We conclude that the presented data shows that pHp is a native part of the surfactant system in the human lung. http://www.diagnosticpathology.diagnomx.eu/vs/2563584738239912.

Ammonium nitrate explosion hazards

Directory of Open Access Journals (Sweden)

Negovanović Milanka

2015-01-01

Full Text Available Ammonium nitrate (AN primarily is used as a fertilizer but it is also very important compound in the production of industrial explosives. The application of ammonium nitrate in the production of industrial explosives was related with the early era of Nobel dynamite and widely increased with the appearance of blasting agents such as ANFO and Slurry, in the middle of the last Century. Throughout the world millions of tons of ammonium nitrate are produced annually and handled without incident. Although ammonium nitrate generally is used safely, accidental explosions involving AN have high impact resulting in loss of lives and destruction of property. The paper presents the basic properties of ammonium nitrate as well as hazards in handling of ammonium nitrate in order to prevent accidents. Several accidents with explosions of ammonium nitrate resulted in catastrophic consequences are listed in the paper as examples of non-compliance with prescribed procedures.

The role of surfactant protein D in chemotherapy-induced gastrointestinal toxicity in mice

DEFF Research Database (Denmark)

Leicht von Huth, Sebastian; Rathe, Mathias; Sørensen, Grith Lykke

Surfactant protein D (SP-D) is a host defense molecule produced by epithelial cells. SP-D is known for its role in pulmonary innate immunology, but is present in mucosa throughout the body. SP-D has been shown to be regulated in the gastrointestinal (GI-) mucosa of chemotherapy-treated piglets...

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)

Acidity Constants Determination of Triazine Dye Derivative in the presence of some Surfactants by Multiwavelength Spectrophotometric and Spectrofluorimetric

Directory of Open Access Journals (Sweden)

Ali Yeganeh Faal

2014-03-01

Full Text Available In this work, acidity constants protonated form of 4.4'-bis astilbene-2,2'-disulfonic-disodium salts (TRIAZ have been determined spectrophotometrically and spectrofluorimetrically at 25◦C and ionic strength of 0.1M KNO3. A program based on MCR-ALS applied for determination of acidity constants. The results show that the peak values of dye are influenced by the presence of anionic, cationic, and nonionic surfactants. The effects of sodium dodecyl sulfate (SDS, Triton X-100 (TX-100 and cetyl trimethyl ammonium bromide (CTAB as a surface-active agent on the acidic and basic forms, and the spectral properties of dye were studied. Also, we determined the critical micelle concentration (CMC for these surfactants by spectrophotometric and spectrofluorimetric triazine dye probes. In addition, by using of evolving factor analysis (EFA and multivariate curve resolution alternative least squares (MCR-ALS methods, acidity constants were acquired.

Bio surfactants production in bioreactor assisted with membrane process; Producao de biossurfactantes em biorreator assistido por processos com membranas

Energy Technology Data Exchange (ETDEWEB)

Kronemberger, Frederico de Araujo; Borges, Cristiano Piacsek [Universidade Federal do Rio de Janeiro (UFRJ). COPPE. Programa de Engenharia Quimica, RJ (Brazil)], e-mails: frederico@peq.coppe.ufrj.br, cristiano@peq.coppe.ufrj.br, s.noblat@csn.com.br; Freire, Denise Maria Guimaraes [Universidade Federal do Rio de Janeiro (UFRJ). Instituto de Quimica. Departamento de Bioquimica, RJ (Brazil)], e-mail: freire@iq.ufrj.br

2010-04-15

Chemically synthesized surfactants are widely used in the pharmaceutical, food and oil industries. However, they may eventually be replaced by bio surfactants, which are biodegradable and produced from renewable substrates, the surface active molecules produced by micro-organisms. Currently bio surfactants use is limited to some specific applications as they are not economically competitive. The fermentation technology needs to be improved to expand the production scale and lower costs. The most studied bio surfactants are produced by aerobic microorganisms. The main difficulty of this fermentation process is the excess foam caused by injecting air into the vessel. To overcome this problem, a membrane contactor can be used for the non-dispersive transfer of oxygen from the gas to liquid phase. The main objective of this study was to produce rhamno lipidic type bio surfactants from a strain of Pseudomonas aeruginosa (PA1), isolated from oil wells. This production used a hollow-fiber membrane contactor to oxygenate the culture medium. The study results indicate this bio surfactant is economically viable in large scale production. (author)

Crystallization characteristics of ammonium uranyl carbonate (AUC) in ammonium carbonate solutions

International Nuclear Information System (INIS)

Kim, T.J.; Jeong, K.C.; Park, J.H.; Chang, I.S.; Choi, C.S.

1994-01-01

Ammonium carbonate solutions with an excessive amount of NH 3 were produced in a commercial AUC (ammonium uranyl carbonate) conversion plant. In this study the AUC crystals, precipitated with uranyl nitrate and ammonium carbonate solutions prepared in the laboratory, were characterized to determine the feasibility of recycling ammonium carbonate solution. The AUC crystals were easily agglomerated with the increasing concentration of CO 3 2- and mole ratio of NH 4 + /CO 3 2- in ammonium carbonate solution. Effects of a mixing system for the solution in the AUC crystallizer and the feed location of the solution onthe agglomeration of AUC crystals were also studied along with the effects of agglomerated AUC powders on UO 2 powders. Finally, the feasibility of manufacturing UO 2 fuel with a sintered pellet density of 10.52 g/cm 3 , using the AUC powders generated in this experiment, was demonstrated. (orig.)

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

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

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

Science.gov (United States)

Mendenhall, Jonathan D.

Surfactants are chemically-heterogeneous molecules possessing hydrophilic (head) and hydrophobic (tail) moieties. This dual nature of surfactants leads to interesting phase behavior in aqueous solution as a function of surfactant concentration, including: (i) formation of surfactant monolayers at surfaces and interfaces, and (ii) self-assembly into finite aggregates (micelles) in the bulk solution beyond the critical micelle concentration (cmc). This concentration-dependent phase behavior induces changes in solution properties. For example, the surface activity of surfactants can decrease the surface tension, and self-assembly in bulk solution can lead to changes in viscosity, equivalent conductivity, solubilization capacity, and other bulk properties. These effects make surfactants quite attractive and unique for use in product formulations, where they are utilized as detergents, dispersants, emulsifiers, solubilizers, surface and interfacial tension modifiers, and in other contexts. The specific chemical structure of the surfactant head and tail is essential in determining the overall performance properties of a surfactant in aqueous media. The surfactant tail drives the self-assembly process through the hydrophobic effect, while the surfactant head imparts a certain extent of solubility to the surfactant in aqueous solution through preferential interactions with the hydrogen-bonding network of water. The interplay between these two effects gives rise to the particular phase diagram of a surfactant, including the specific cmc at which micelles begin to form. In addition to serving as a quantitative indicator of micelle formation, the cmc represents a limit to surface monolayer formation, and hence to surface and interfacial tension reduction, because surfactant adsorption at interfaces remains approximately constant beyond the cmc. In addition, the cmc represents the onset of changes in bulk solution properties. This Thesis is concerned with the prediction of cmc

Communication: Salt-induced water orientation at a surface of non-ionic surfactant in relation to a mechanism of Hofmeister effect

Energy Technology Data Exchange (ETDEWEB)

Hishida, Mafumi; Kaneko, Yohei; Okuno, Masanari; Yamamura, Yasuhisa; Ishibashi, Taka-aki; Saito, Kazuya, E-mail: kazuya@chem.tsukuba.ac.jp [Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571 (Japan)

2015-05-07

The behavior of water molecules at the surface of nonionic surfactant (monomyristolein) and effects of monovalent ions on the behavior are investigated using the heterodyne-detected vibrational sum frequency generation spectroscopy. It is found that water molecules at the surface are oriented with their hydrogen atoms pointing to the bulk, and that the degree of orientation depends on the anion strongly but weakly on the cation. With measured surface potentials in those saline solutions, it is concluded that the heterogeneous distribution of anions and cations in combination with the nonionic surfactant causes the water orientation. This heterogeneous distribution well explains the contrasting order of anions and cations with respect to the ion size in the Hofmeister series.

Communication: Salt-induced water orientation at a surface of non-ionic surfactant in relation to a mechanism of Hofmeister effect

International Nuclear Information System (INIS)

Hishida, Mafumi; Kaneko, Yohei; Okuno, Masanari; Yamamura, Yasuhisa; Ishibashi, Taka-aki; Saito, Kazuya

2015-01-01

The behavior of water molecules at the surface of nonionic surfactant (monomyristolein) and effects of monovalent ions on the behavior are investigated using the heterodyne-detected vibrational sum frequency generation spectroscopy. It is found that water molecules at the surface are oriented with their hydrogen atoms pointing to the bulk, and that the degree of orientation depends on the anion strongly but weakly on the cation. With measured surface potentials in those saline solutions, it is concluded that the heterogeneous distribution of anions and cations in combination with the nonionic surfactant causes the water orientation. This heterogeneous distribution well explains the contrasting order of anions and cations with respect to the ion size in the Hofmeister series

Dynamic strength of the interaction between lung surfactant protein D (SP-D) and saccharide ligands

DEFF Research Database (Denmark)

Thormann, Esben; Dreyer, Jakob K; Simonsen, Adam C

2007-01-01

In order to investigate the dynamic strength of the interaction between lung surfactant protein D (SP-D) and different sugars, maltose, mannose, glucose, and galactose, we have used an atomic force microscope to monitor the interaction on a single molecule scale. The experiment is performed...

Surfactant-assisted carbon doping in ZnO nanowires using Poly Ethylene Glycol (PEG)

Energy Technology Data Exchange (ETDEWEB)

Amanullah, Malik; Javed, Qurat-ul-Ain, E-mail: Quratulain@sns.nust.edu.pk; Rizwan, Syed

2016-09-01

Zinc Oxide (ZnO) provides unique properties owing to its wide bandgap, large resistivity range and possibility to tune the physical properties. The surfactant assisted carbon doping was made possible due to the lowering of surface energy. The ZnO and carbon doped ZnO (C-ZnO) nanowires fabricated by hydrothermal process, Poly Ethylene Glycol (PEG) is used as surfactant in hydrothermal synthesis followed by post growth annealing treatment at 600 °C–700 °C. At 5%–10% of diluted PEG carbon is doped in ZnO. The crystallinity, structural morphology and elemental composition analysis for ZnO and C-ZnO nanowires were carried out using X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques respectively. Carbon doping in ZnO nanowires in the presence of different percentage of surfactant is explained by calculating the change in surface energy with respect to change in PEG molecule concentration. It was found that the surface energy per molecule modulates from 3.92 × 10{sup −8} J/m{sup 2} to 8.16 × 10{sup −7} J/m{sup 2} in the PEG concentration range between 5% and 10%. Our results provides a new theoretical calculations, implemented on real system, to observe the details of PEG-assisted Carbon doping in II-VI semiconductor nanowires. - Highlights: • ZnO and C-ZnO was synthesized by PEG assisted post growth annealing process. • At 5% and 10% of PEG successful synthesis of C-ZnO was found. • XRD, SEM and EDX characterizations confirm the successful synthesis of ZnO and C-ZnO. • Change in surface energy with respect to PEG molecule concentration was calculated.

Nanoscopic surfactant behavior of the porin MspA in aqueous media

Directory of Open Access Journals (Sweden)

Ayomi S. Perera

2013-04-01

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

Microfluidic processing of concentrated surfactant mixtures: online SAXS, microscopy and rheology.

Science.gov (United States)

Martin, Hazel P; Brooks, Nicholas J; Seddon, John M; Luckham, Paul F; Terrill, Nick J; Kowalski, Adam J; Cabral, João T

2016-02-14

We investigate the effect of microfluidic flow on the microstructure and dynamics of a model surfactant mixture, combining synchrotron Small Angle X-ray Scattering (SAXS), microscopy and rheology. A system comprising a single-chain cationic surfactant, hexadecyl trimethyl ammonium chloride (C16TAC), a short-chain alcohol (1-pentanol) and water was selected for the study due to its flow responsiveness and industrial relevance. Model flow fields, including sequential contraction-expansion (extensional) and rotational flows, were investigated and the fluid response in terms of the lamellar d-spacing, orientation and birefringence was monitored in situ, as well as the recovery processes after cessation of flow. Extensional flows are found to result in considerable d-spacing increase (from approx 59 Å to 65 Å). However, under continuous flow, swelling decreases with increasing flow velocity, eventually approaching the equilibrium values at velocities ≃2 cm s(-1). Through individual constrictions we observe the alignment of lamellae along the flow velocity, accompanied by increasing birefringence, followed by an orientation flip whereby lamellae exit perpendicularly to the flow direction. The resulting microstructures are mapped quantitatively onto the flow field in 2D with 200 μm spatial resolution. Rotational flows alone do not result in appreciable changes in lamellar spacing and flow type and magnitude evidently impact the fluid microstructure under flow, as well as upon relaxation. The findings are correlated with rheological properties measured ex situ to provide a mechanistic understanding of the effect of flow imposed by tubular processing units in the phase behavior and performance of a model surfactant system with ubiquitous applications in personal care and coating industries.

Estimating the contribution of surfactant replacement therapy to the alveolar pool: an in vivo study based on 13 C natural abundance in rabbits.

Science.gov (United States)

Giambelluca, Sonia; Ricci, Francesca; Simonato, Manuela; Correani, Alessio; Casiraghi, Costanza; Storti, Matteo; Cogo, Paola; Salomone, Fabrizio; Carnielli, Virgilio Paolo

2018-04-06

Variation of the isotopic abundance of selected nutrients and molecules have been used for pharmacological and kinetics studies under the premise that the administered molecule has a different isotopic enrichment from the isotopic background of the recipient subject. The aim of this study is to test the feasibility of assessing the contribution of exogenous surfactant phospholipids to the endogenous alveolar pool in vivo after exogenous surfactant replacement therapy in rabbits. The study consisted in measuring the consistency of 13 C/ 12 C ratio of disaturated-phosphatidylcholine palmitate (DSPC-PA) in 7 lots of poractant alfa, produced over a year, and among bronchoalveolar lavages of 20 rabbits fed with a standard chow. A pilot study was performed in a rabbit model of lavage-induced surfactant deficiency: 7 control rabbits and 4 treated with exogenous surfactant. The contribution of exogenous surfactant to the alveolar pool was assessed after intra-tracheal administration of 200 mg/kg of poractant alfa. The 13 C content of DSPC-PA was measured by Isotope Ratio Mass Spectrometry. The mean DSPC-PA 13 C/ 12 C ratio of the 7 lots of poractant alfa was -18.8 ‰ with a SD of 0.1 ‰ [Range: -18.9 ‰; -18.6 ‰]. The mean 13 C/ 12 C ratio of surfactant DSPC recovered from the lung lavage of 20 rabbits was -28.8±1.2 ‰ [Range: -31.7 ‰; -25.7 ‰]. The contribution of exogenous surfactant to the total alveolar surfactant could be calculated in the treated rabbits and it ranged from 83.9 to 89.6 %. This pilot study describes a novel method to measure the contribution of the exogenous surfactant to the alveolar pool. This method is based on the natural variation of 13 C and therefore it does not require the use of chemically synthetized tracers. This method could be useful in human research and especially in surfactant replacement studies in preterm infants. This article is protected by copyright. All rights reserved.

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

Micellar Surfactant Association in the Presence of a Glucoside-based Amphiphile Detected via High-Throughput Small Angle X-ray Scattering

Energy Technology Data Exchange (ETDEWEB)

Stanic, Vesna [Brazilian Synchrotron Light Source, Campinas (Brazil); Broadbent, Charlotte [Columbia Univ., New York, NY (United States). Engineering Dept.; DiMasi, Elaine [Brookhaven National Lab. (BNL), Upton, NY (United States). Photon Sciences Division; Galleguillos, Ramiro [Lubrizol Advanced Materials, Cleveland, OH (United States); Woodward, Valerie [Lubrizol Advanced Materials, Cleveland, OH (United States)

2016-11-14

The interactions of mixtures of anionic and amphoteric surfactants with sugar amphiphiles were studied via high throughput small angle x-ray scattering (SAXS). The sugar amphiphile was composed of Caprate, Caprylate, and Oleate mixed ester of methyl glucoside, MeGCCO. Optimal surfactant interactions are sought which have desirable physical properties, which must be identified in a cost effective manner that can access the large phase space of possible molecular combinations. X-ray scattering patterns obtained via high throughput SAXS can probe a combinatorial sample space and reveal the incorporation of MeGCCO into the micelles and the molecular associations between surfactant molecules. Such data make it possible to efficiently assess the effects of the new amphiphiles in the formulation. A specific finding of this study is that formulations containing comparatively monodisperse and homogeneous surfactant mixtures can be reliably tuned by addition of NaCl, which swells the surfactant micelles with a monotonic dependence on salt concentration. In contrast, the presence of multiple different surfactants destroys clear correlations with NaCl concentration, even in otherwise similar series of formulations.

Surfactant -- Where Are We in 2003?

Directory of Open Access Journals (Sweden)

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.

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

Science.gov (United States)

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

2014-10-01

In this contribution, we provide an accurate characterization at the α-pinene/water interface of two commercial polyoxytheylene glycerol ester surfactants which differ in the number of ethylene oxide (EO) groups, comprising a systematic analysis of interfacial pressure isotherms, dynamic curves, interfacial rheology and emulsifying properties. Polyoxyethylene glycerol esters derived from cocoa oil are non-ionic surfactants obtained from a renewable source which fulfill the environmental and toxicological requirements to be used as eco-friendly emulsifying agents. α-Pinene is a renewable biosolvent completely insoluble in water, which could find numerous applications. Interfacial rheology and equilibrium interfacial pressure data fitted a rigorous reorientation model that assumes that the surfactant molecules, when adsorbed at the interface, can acquire two orientations. The surfactant with the highest number of EO groups (Levenol C201) turned out to be more surface active at the α-pinene/water interface. In addition, the surfactant with the lowest number of EO groups (Levenol H&B) is solubilized into the adjacent oil phase. Slightly concentrated α-pinene emulsions were obtained using both surfactants. Nevertheless, more stable α-pinene emulsions with smaller droplet sizes and lower polidispersity were obtained when Levenol C201 was used as emulsifier instead of Levenol H&B. The systematic characterization presented in this work provides important new findings on the interfacial and emulsifying properties of polyoxytheylene glycerol ester surfactants, which can be applied in the rational development of new biocompatible products. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of surfactants on the deformation of single droplet in shear flow studied by dissipative particle dynamics

Science.gov (United States)

Zhang, Yuzhou; Xu, Junbo; He, Xianfeng

2018-07-01

The behaviour of a single droplet in shear flow is a fundamental problem in immiscible liquid-liquid multiphase fluid systems. In this article, the deformation and inclination angle of single droplet covered with surfactants in shear flow at moderate Reynolds number, when both the inertial effects and interfacial tension are the key governing factors, were simulated by dissipative particle dynamics (DPD). Weber number We was adopted to indicate the force state of the droplet and a linear relationship between the deformation parameter D and We was found when Reynolds number Re is about 1-10, which is similar to the relation of D and Capillary number Ca when Re ≪ 1. When the surfactant concentration is lower than the critical micelle concentration (CMC), the distribution of surfactants, the droplet inclination angle θ and the droplet deformation parameter D were investigated at different surfactant density at interface ds and shear rate ?. When the droplet size is close to the characteristic size of surfactant molecules, phase interfaces of water in oil (W/O) and oil in water (O/W) systems have different microstructures, which result in differences in the surfactant distribution, the droplet inclination angle and deformation of the two systems.

Surfactant adsorption study in sandstone for enhanced oil recovery; Estudo da adsorcao de tensoativos em arenitos para recuperacao avancada de petroleo

Energy Technology Data Exchange (ETDEWEB)

Curbelo, Fabiola D.S.; Santanna, Vanessa C.; Barros Neto, Eduardo L. de; Dutra Junior, Tarcilio V.; Dantas Neto, Afonso A. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Dept. de Engenharia Quimica; Garnica, Alfredo I.C. [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Dept. de Tecnologia Quimica e de Alimentos; Lucena Neto, Marciano [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Dantas, Tereza N.C. [Faculdade Natalense para o Desenvolvimento do RN (FARN), Natal, RN (Brazil)

2004-07-01

Adsorption of surfactants from aqueous solutions in porous media is very important in Enhanced Oil Recovery (EOR) of oil reservoirs because surfactant loss due to adsorption on the reservoir rocks weakens the effectiveness of the injected chemical slug in reducing oil-water tension (IFT) and makes the process uneconomical. In this paper, two nonionic surfactants, such as alkyl phenol polyoxyethylene, with different ethoxylation degrees were studied, ENP95 and ENP150. The results of flow experiments of surfactant solutions in porous media showed that adsorption was higher for ENP95 because it has smaller ethoxylation degree than ENP150. This occurs what with increasing length of the head group, the molecules become more hydrophilic and, in associated structures, the steric hindrance between the head groups increases. Generally speaking, adsorption appears to be a cooperative process involving lateral interaction between surfactant and weak interaction with the solid surface. (author)

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.

Crystallisation of mixtures of ammonium nitrate, ammonium sulphate and soot

NARCIS (Netherlands)

Dougle, P.G.; Veefkind, J.P.; Brink, H.M. ten

1998-01-01

Crystallisation of laboratory aerosols of ammonium nitrate and of internal mixtures of this salt with ammonium sulphate were investigated using humidity controlled nephelometry. The aerosol was produced via nebulizing of solutions and then dried to 25% RH, which is a realistic minimum value for

Ultrafast dynamics of solvation and charge transfer in a DNA-based biomaterial.

Science.gov (United States)

Choudhury, Susobhan; Batabyal, Subrata; Mondol, Tanumoy; Sao, Dilip; Lemmens, Peter; Pal, Samir Kumar

2014-05-01

Charge migration along DNA molecules is a key factor for DNA-based devices in optoelectronics and biotechnology. The association of a significant amount of water molecules in DNA-based materials for the intactness of the DNA structure and their dynamic role in the charge-transfer (CT) dynamics is less documented in contemporary literature. In the present study, we have used a genomic DNA-cetyltrimethyl ammonium chloride (CTMA) complex, a technological important biomaterial, and Hoechest 33258 (H258), a well-known DNA minor groove binder, as fluorogenic probe for the dynamic solvation studies. The CT dynamics of CdSe/ZnS quantum dots (QDs; 5.2 nm) embedded in the as-prepared and swollen biomaterial have also been studied and correlated with that of the timescale of solvation. We have extended our studies on the temperature-dependent CT dynamics of QDs in a nanoenvironment of an anionic, sodium bis(2-ethylhexyl)sulfosuccinate reverse micelle (AOT RMs), whereby the number of water molecules and their dynamics can be tuned in a controlled manner. A direct correlation of the dynamics of solvation and that of the CT in the nanoenvironments clearly suggests that the hydration barrier within the Arrhenius framework essentially dictates the charge-transfer dynamics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Science.gov (United States)

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

2014-11-18

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

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.

Directory of Open Access Journals (Sweden)

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.

Thermodynamic solution properties of pefloxacin mesylate and its interactions with organized assemblies of anionic surfactant, sodium dodecyl sulphate

International Nuclear Information System (INIS)

Usman, Muhammad; Rashid, Muhammad Abid; Mansha, Asim; Siddiq, Mohammad

2013-01-01

Graphical abstract: - Highlights: • Free energy of adsorption is more negative than free energy of micellization. • Micellization becomes more spontaneous at high temperature. • There is strong interaction between PFM and SDS. - Abstract: This manuscript reports the physicochemical behavior of antibiotic amphiphilic drug pefloxacin mesylate (PFM) and its interaction with anionic surfactant, sodium dodecyl sulfate (SDS). The data of surface tension and electrical conductivity are helpful to detect the CMC as well as to calculate surface parameters, i.e. surface pressure, π, surface excess concentration, Γ, area per molecule of drug and standard Gibbs free energy of adsorption, ΔG ads and thermodynamic parameters like standard free energy of micellization, ΔG m , standard enthalpy of micellization, ΔH m and standard entropy of micellization, ΔS m . The interaction of this drug with anionic surfactant, sodium dodecyl sulfate (SDS) was studied by electrical conductivity and UV/visible spectroscopy. This enabled us to compute the values of partition coefficient (K x ), free energy of partition, ΔG p , binding constant, K b , free energy of binding, ΔG b , number of drug molecules per micelle, n, and thermodynamic parameters of drug–surfactant interaction

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

Surfactant-induced skin irritation and skin repair: evaluation of a cumulative human irritation model by noninvasive techniques.

Science.gov (United States)

Wilhelm, K P; Freitag, G; Wolff, H H

1994-12-01

Although surfactant-induced acute irritant dermatitis has been extensively studied, our understanding about the induction and repair of the clinically more relevant chronic form is limited. Our purpose was to investigate qualitative and quantitative differences in surfactant-induced irritant skin reactions from cumulative exposure to structurally unrelated surfactants and to compare the maximal irritant responses from this model with corresponding reactions noted in a previously reported acute irritation model. Sodium lauryl sulfate (SLS), dodecyl trimethyl ammonium bromide (DTAB), and potassium soap were the model irritants. Surfactant solutions (7.5%) were applied for 20 minutes daily (for 8 consecutive days excluding the weekend) to the volar aspect of the forearm of 11 volunteers. Irritant reactions were repeatedly assessed until complete healing was indicated by visual assessment and by measurements of transepidermal water loss (TEWL), erythema (skin color reflectance), and stratum corneum hydration (electrical capacitance). Maximum irritant responses were compared with corresponding reactions from an acute irritation model. TEWL was increased by SLS and DTAB to the same extent, but erythema was significantly higher in DTAB-treated skin. Skin dryness, as demonstrated by decreased capacitance values and increased scores for scaling and fissuring, was significantly more pronounced than in an acute irritation model for SLS and DTAB, although no difference was detected between the two surfactants. Potassium soap led to a slight increase in TEWL, whereas the remaining features were not significantly changed. This chronic irritation model appears to represent the clinical situation of irritant contact dermatitis with pronounced skin dryness more closely than the acute irritation model. The present study confirms that an extended time is needed for complete healing of irritant skin reactions. We also demonstrated that the evaluation of the irritation potential of

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

49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.

Science.gov (United States)

2010-10-01

... nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 Transportation Other... requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers. (a) Except as... Captain of the Port (COTP). (1) Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more than...

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.

Surfactant-dependent macrophage response to polypyrrole-based coatings electrodeposited on Ti6Al7Nb alloy

Energy Technology Data Exchange (ETDEWEB)

Mindroiu, Mihaela [University Polytechnica of Bucharest, Faculty of Applied Chemistry and Materials Science, 1-7 Polizu, 011061, Bucharest (Romania); Ion, Raluca [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095, Bucharest (Romania); Pirvu, Cristian [University Polytechnica of Bucharest, Faculty of Applied Chemistry and Materials Science, 1-7 Polizu, 011061, Bucharest (Romania); Cimpean, Anisoara, E-mail: anisoara.cimpean@bio.unibuc.ro [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095, Bucharest (Romania)

2013-08-01

In this study, polypyrrole (PPy) films were successfully synthesized on Ti6Al7Nb alloy by potentiostatic polymerization in the presence of poly(sodium 4-styrenesulfonate) (NaPSS), t-octylphenoxy polyethoxyethanol (Triton X-100) and N-dodecyl-β-D-maltoside (DM) surfactants. Atomic force microscopy (AFM) analysis of the PPy/surfactant composite films revealed a granular structure characterized by a lower surface roughness than un-modified PPy films. The results demonstrated that addition of surfactants, namely Triton X-100 and DM, can improve electrochemical film stability and corrosion resistance. Further, Triton X-100 enhanced the adhesive strength of PPy films to the substrate. The surfactant type also showed a great influence on the surface wettability, the highest hydrophilic character being observed in the case of PPy/PSS film. Few studies have been devoted to the elucidation of inflammatory cell response to PPy-based materials. Therefore, RAW 264.7 macrophages were cultured on PPy-surfactant films to determine whether they elicit a differential cell behavior in terms of cell adhesion, proliferation, cellular morphology and cytokine secretion. Our results highlight the dependence of macrophage response on the surfactants used in the pyrrole polymerization process and suggest that the immune response to biomaterials coated with PPy films might be controlled by the choice of surfactant molecules. Highlights: • We electrodeposited polypyrrole films on Ti6Al7Nb alloy using three surfactants. • Differences in electrostability and wettability of polypyrrole films were found. • Triton X increased and NaPSS decreased the adhesion of polypyrrole films to Ti6Al7Nb. • Cytoskeletal architecture and macrophage activation were affected by surfactants. • The hydrophilic PPy/PSS coating elicited the lowest inflammatory response.

Surfactant-dependent macrophage response to polypyrrole-based coatings electrodeposited on Ti6Al7Nb alloy

International Nuclear Information System (INIS)

Mindroiu, Mihaela; Ion, Raluca; Pirvu, Cristian; Cimpean, Anisoara

2013-01-01

In this study, polypyrrole (PPy) films were successfully synthesized on Ti6Al7Nb alloy by potentiostatic polymerization in the presence of poly(sodium 4-styrenesulfonate) (NaPSS), t-octylphenoxy polyethoxyethanol (Triton X-100) and N-dodecyl-β-D-maltoside (DM) surfactants. Atomic force microscopy (AFM) analysis of the PPy/surfactant composite films revealed a granular structure characterized by a lower surface roughness than un-modified PPy films. The results demonstrated that addition of surfactants, namely Triton X-100 and DM, can improve electrochemical film stability and corrosion resistance. Further, Triton X-100 enhanced the adhesive strength of PPy films to the substrate. The surfactant type also showed a great influence on the surface wettability, the highest hydrophilic character being observed in the case of PPy/PSS film. Few studies have been devoted to the elucidation of inflammatory cell response to PPy-based materials. Therefore, RAW 264.7 macrophages were cultured on PPy-surfactant films to determine whether they elicit a differential cell behavior in terms of cell adhesion, proliferation, cellular morphology and cytokine secretion. Our results highlight the dependence of macrophage response on the surfactants used in the pyrrole polymerization process and suggest that the immune response to biomaterials coated with PPy films might be controlled by the choice of surfactant molecules. Highlights: • We electrodeposited polypyrrole films on Ti6Al7Nb alloy using three surfactants. • Differences in electrostability and wettability of polypyrrole films were found. • Triton X increased and NaPSS decreased the adhesion of polypyrrole films to Ti6Al7Nb. • Cytoskeletal architecture and macrophage activation were affected by surfactants. • The hydrophilic PPy/PSS coating elicited the lowest inflammatory response

A solid phase extraction-ion chromatography with conductivity detection procedure for determining cationic surfactants in surface water samples.

Science.gov (United States)

Olkowska, Ewa; Polkowska, Żaneta; Namieśnik, Jacek

2013-11-15

A new analytical procedure for the simultaneous determination of individual cationic surfactants (alkyl benzyl dimethyl ammonium chlorides) in surface water samples has been developed. We describe this methodology for the first time: it involves the application of solid phase extraction (SPE-for sample preparation) coupled with ion chromatography-conductivity detection (IC-CD-for the final determination). Mean recoveries of analytes between 79% and 93%, and overall method quantification limits in the range from 0.0018 to 0.038 μg/mL for surface water and CRM samples were achieved. The methodology was applied to the determination of individual alkyl benzyl quaternary ammonium compounds in environmental samples (reservoir water) and enables their presence in such types of waters to be confirmed. In addition, it is a simpler, less time-consuming, labour-intensive, avoiding use of toxic chloroform and significantly less expensive methodology than previously described approaches (liquid-liquid extraction coupled with liquid chromatography-mass spectrometry). Copyright © 2013 Elsevier B.V. All rights reserved.

The role of charge in the surfactant-assisted stabilization of the natural product curcumin.

Science.gov (United States)

Wang, Zifan; Leung, Mandy H M; Kee, Tak W; English, Douglas S

2010-04-20

Colloidal solutions of surfactants that form micelles or vesicles are useful for solubilizing and stabilizing hydrophobic molecules that are otherwise sparingly soluble in aqueous solutions. In this paper we investigate the use of micelles and vesicles prepared from ionic surfactants for solubilizing and stabilizing curcumin, a medicinal natural product that undergoes alkaline hydrolysis in water. We identify spectroscopic signatures to evaluate curcumin partitioning and deprotonation in surfactant mixtures containing micelles or vesicles. These spectroscopic signatures allow us to monitor the interaction of curcumin with charged surfactants over a wide range of pH values. Titration data are presented to show the pH dependence of curcumin interactions with negatively and positively charged micelles and vesicles. In solutions of cationic micelles or positively charged vesicles, strong interaction between the Cur(-1) phenoxide ion and the positively charged surfactants results in a change in the acidity of the phenolic hydrogen and a lowering of the apparent lowest pK(a) value for curcumin. In the microenvironments formed by anionic micelles or negatively charged bilayers, our data indicates that curcumin partitions as the Cur(0) species, which is stabilized by interactions with the respective surfactant aggregates, and this leads to an increase in the apparent pK(a) values. Our results may explain some of the discrepancies within the literature with respect to reported pK(a) values and the acidity of the enolic versus phenolic protons. Hydrolysis rates, quantum yields, and molar absorption coefficients are reported for curcumin in a variety of solutions.

Microbiological Production of Surfactant from Agricultural Residuals for IOR Application

Energy Technology Data Exchange (ETDEWEB)

Bala, Greg Alan; Bruhn, Debby Fox; Fox, Sandra Lynn; Noah, Karl Scott; Thompson, David Neal

2002-04-01

Utilization of surfactants for improved oil recovery (IOR) is an accepted technique with high potential. However, technology application is frequently limited by cost. Biosurfactants (surface-active molecules produced by microorganisms) are not widely utilized in the petroleum industry due to high production costs associated with use of expensive substrates and inefficient product recovery methods. The economics of biosurfactant production could be significantly impacted through use of media optimization and application of inexpensive carbon substrates such as agricultural process residuals. Utilization of biosurfactants produced from agricultural residuals may 1) result in an economic advantage for surfactant production and technology application, and 2) convert a substantial agricultural waste stream to a value-added product for IOR. A biosurfactant with high potential for use is surfactin, a lipopeptide biosurfactant, produced by Bacillus subtilis. Reported here is the production and potential IOR utilization of surfactin produced by Bacillus subtilis (American Type Culture Collection (ATCC) 21332) from starch-based media. Production of surfactants from microbiological growth media based on simple sugars, chemically pure starch medium, simulated liquid and solid potato-process effluent media, a commercially prepared potato starch in mineral salts, and process effluent from a potato processor is discussed. Additionally, the effect of chemical and physical pretreatments on starchy feedstocks is discussed.

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

Directory of Open Access Journals (Sweden)

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

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

Influence of alkyl chain length and temperature on thermophysical properties of ammonium-based ionic liquids with molecular solvent.

Science.gov (United States)

Kavitha, T; Attri, Pankaj; Venkatesu, Pannuru; Devi, R S Rama; Hofman, T

2012-04-19

Mixing of ionic liquids (ILs) with molecular solvent can expand the range of structural properties and the scope of molecular interactions between the molecules of the solvents. Exploiting of these phenomena essentially require a basic fundamental understanding of mixing behavior of ILs with molecular solvents. In this context, a series of protic ILs possessing tetra-alkyl ammonium cation [R(4)N](+) with commonly used anion hydroxide [OH](-) were synthesized and characterized by temperature dependent thermophysical properties. The ILs [R(4)N](+)[OH](-) are varying only in the length of alkyl chain (R is methyl, ethyl, propyl, or butyl) of tetra-alkyl ammonium on the cationic part. The ILs used for the present study included tetramethyl ammonium hydroxide [(CH(3))(4)N](+)[OH](-) (TMAH), tetraethyl ammonium hydroxide [(C(2)H(5))(4)N](+)[OH](-) (TEAH), tetrapropyl ammonium hydroxide [(C(3)H(7))(4)N](+)[OH](-) (TPAH) and tetrabutyl ammonium hydroxide [(C(4)H(9))(4)N](+)[OH](-) (TBAH). The alkyl chain length effect has been analyzed by precise measurements such as densities (ρ), ultrasonic sound velocity (u), and viscosity (η) of these ILs with polar solvent, N-methyl-2-pyrrolidone (NMP), over the full composition range as a function of temperature. The excess molar volume (V(E)), the deviation in isentropic compressibility (Δκ(s)) and deviation in viscosity (Δη) were predicted using these properties as a function of the concentration of ILs. Redlich-Kister polynomial was used to correlate the results. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and NMP molecules. Later, the hydrogen bonding features between ILs and NMP were also analyzed using a molecular modeling program with the help of HyperChem 7.

Strong cooperative effect of oppositely charged surfactant mixtures on their adsorption and packing at the air-water interface and interfacial water structure.

Science.gov (United States)

Nguyen, Khoi T; Nguyen, Tuan D; Nguyen, Anh V

2014-06-24

Remarkable adsorption enhancement and packing of dilute mixtures of water-soluble oppositely-charged surfactants, sodium dodecyl sulfate (SDS) and dodecyl amine hydrochloride (DAH), at the air-water interface were observed by using sum frequency generation spectroscopy and tensiometry. The interfacial water structure was also observed to be significantly influenced by the SDS-DAH mixtures, differently from the synergy of the single surfactants. Most strikingly, the obtained spectroscopic evidence suggests that the interfacial hydrophobic alkyl chains of the binary mixtures assemble differently from those of single surfactants. This study highlights the significance of the cooperative interaction between the headgroups of oppositely charged binary surfactant systems and subsequently provides some insightful observations about the molecular structure of the air-aqueous interfacial water molecules and, more importantly, about the packing nature of the surfactant hydrophobic chains of dilute SDS-DAH mixtures of concentration below 1% of the CMC.

Waterproofing Materials for Ammonium Nitrate

OpenAIRE

R.S. Damse

2004-01-01

This study explores the possibility of overcoming the problem of hygroscopicity of ammonium nitrate by coating the particles with selected waterproofing materials. Gravimetric analysis ofthe samples of ammonium nitrate coated with eight different waterproofing materials, vis-a-vis, uncoated ammonium nitrate, were conducted at different relative humidity and exposuretime. The results indicate that mineral jelly is the promising waterproofing material for ammonium nitrate among the materials te...

49 CFR 176.410 - Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures.

Science.gov (United States)

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. 176.410 Section 176.410 Transportation Other Regulations Relating to... nitrate and ammonium nitrate mixtures. (a) This section prescribes requirements to be observed with...

Ammonium-induced inhibition of ammonium-starved Nitrosomonas europaea cells in soil and sand slurries

NARCIS (Netherlands)

Gerards, S.; Duyts, H.; Laanbroek, H.J.

1998-01-01

Ammonia-oxidising bacteria are poor competitors for limiting amounts of ammonium. Hence, starvation for ammonium seems to be the regular condition for these bacteria in natural environments. Long-term survival in the absence of ammonium will be dependent on the ability to maintain large population

Extracting Aggregation Free Energies of Mixed Clusters from Simulations of Small Systems: Application to Ionic Surfactant Micelles.

Science.gov (United States)

Zhang, X; Patel, L A; Beckwith, O; Schneider, R; Weeden, C J; Kindt, J T

2017-11-14

Micelle cluster distributions from molecular dynamics simulations of a solvent-free coarse-grained model of sodium octyl sulfate (SOS) were analyzed using an improved method to extract equilibrium association constants from small-system simulations containing one or two micelle clusters at equilibrium with free surfactants and counterions. The statistical-thermodynamic and mathematical foundations of this partition-enabled analysis of cluster histograms (PEACH) approach are presented. A dramatic reduction in computational time for analysis was achieved through a strategy similar to the selector variable method to circumvent the need for exhaustive enumeration of the possible partitions of surfactants and counterions into clusters. Using statistics from a set of small-system (up to 60 SOS molecules) simulations as input, equilibrium association constants for micelle clusters were obtained as a function of both number of surfactants and number of associated counterions through a global fitting procedure. The resulting free energies were able to accurately predict micelle size and charge distributions in a large (560 molecule) system. The evolution of micelle size and charge with SOS concentration as predicted by the PEACH-derived free energies and by a phenomenological four-parameter model fit, along with the sensitivity of these predictions to variations in cluster definitions, are analyzed and discussed.

Kinetic study of the hydrolysis of 1-(4-nitrophenyl)-3-methyltriazene in aqueous solution and in the presence of surfactants.

Science.gov (United States)

Ebert, C; Lassiani, L; Linda, P; Lovrecich, M; Nisi, C; Rubessa, F

1984-12-01

The hydrolysis of 1-(4-nitrophenyl)-3-methyltriazene in aqueous solution has been studied over a pH range of 3-14. The effect of the anionic and cationic surfactants (sodium lauryl sulfate and hexadecyltrimethylammonium bromide) on the rate of hydrolysis was investigated. The quaternary ammonium bromide causes a rate decrease at all pH values studied, while sodium lauryl sulfate enhances the acid-catalyzed hydrolysis and decreases the observed rate constants in the pH-independent region. The results are discussed in terms of the current theory of micellar effects.

Catalysis of the Oligomerization of O-Phospho-Serine, Aspartic Acid, or Glutamic Acid by Cationic Micelles

Science.gov (United States)

Bohler, Christof; Hill, Aubrey R., Jr.; Orgel, Leslie E.

1996-01-01

Treatment of relatively concentrated aqueous solutions of 0-phospho-serine (50 mM), aspartic acid (100 mM) or glutamic acid (100 mM) with carbonyldiimidazole leads to the formation of an activated intermediate that oligomerizes efficiently. When the concentration of amino acid is reduced tenfold, few long oligomers can be detected. Positively-charged cetyltrimethyl ammonium bromide micelles concentrate the negatively-charged activated intermediates of the amino acids at their surfaces and catalyze efficient oligomerization even from dilute solutions.

Short-range interactions between surfactants, silica species and EDTA⁴- salt during self-assembly of siliceous mesoporous molecular sieve: a UV Raman study.

Science.gov (United States)

Song, Jiayin; Liu, Liping; Li, Peng; Xiong, Guang

2012-11-01

The effects of surfactants, counterions and additive salts on the formation of siliceous mesoporous molecular sieves during self-assembly process were investigated by UV Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. The surfactant molecules experience the rearrangement after adding the silica species and adjusting the pH value. The obvious change of the Raman bands related to the surfactants supports a cooperative interaction between surfactant and inorganic species during self-assembly process. The addition of EDTANa(4) to the system induces the interaction between the COO(-) groups of EDTA(4-) and silanol groups of silica and a strong interaction between the EDTA(4-) and the N(+)(CH(3))(3) groups of the surfactant. The above interactions may be the main reason for the salt effect. The new information from the change of the chemical bonds allows for a further analysis to the interactions of different salts between surfactants and silica species at molecular level. Copyright © 2012 Elsevier B.V. All rights reserved.

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.

Acidic Pretreatment of Wheat Straw in Decanol for the Production of Surfactant, Lignin and Glucose

Directory of Open Access Journals (Sweden)

Boris Estrine

2011-12-01

Full Text Available Wheat straw is an abundant residue of agriculture which is increasingly being considered as feedstock for the production of fuels, energy and chemicals. The acidic decanol-based pre-treatment of wheat straw has been investigated in this work. Wheat straw hemicellulose has been efficiently converted during a single step operation into decyl pentoside surfactants and the remaining material has been preserved keeping all its promises as potential feedstock for fuels or value added platform chemicals such as hydroxymethylfurfural (HMF. The enzymatic digestibility of the cellulose contained in the straw residue has been evaluated and the lignin prepared from the material characterized. Wheat-based surfactants thus obtained have exhibited superior surface properties compared to fossil-based polyethoxylates decyl alcohol or alkyl oligoglucosides, some of which are largely used surfactants. In view of the growing importance of renewable resource-based molecules in the chemical industry, this approach may open a new avenue for the conversion of wheat straw into various chemicals.

Catalytic reduction of organic dyes at gold nanoparticles impregnated silica materials: influence of functional groups and surfactants

International Nuclear Information System (INIS)

Azad, Uday Pratap; Ganesan, Vellaichamy; Pal, Manas

2011-01-01

Gold nanoparticles (Au NPs) in three different silica based sol–gel matrixes with and without surfactants are prepared. They are characterized by UV–vis absorbance and transmission electron microscopic (TEM) studies. The size and shape of Au NPs varied with the organo-functional group present in the sol–gel matrix. In the presence of mercaptopropyl functionalized organo-silica, large sized (200–280 nm) spherical Au NPs are formed whereas in the presence of aminopropyl functionalized organo-silica small sized (5–15 nm) Au NPs are formed inside the tube like organo-silica. Further, it is found that Au NPs act as efficient catalyst for the reduction of organic dyes. The catalytic rate constant is evaluated from the decrease in absorbance of the dye molecules. Presence of cationic or anionic surfactants greatly influences the catalytic reaction. The other factors like hydrophobicity of the organic dyes, complex formation of the dyes with anionic surfactants, repulsion between dyes and cationic surfactant, adsorption of dyes on the Au NPs also play important role on the reaction rate.

Catalytic reduction of organic dyes at gold nanoparticles impregnated silica materials: influence of functional groups and surfactants

Energy Technology Data Exchange (ETDEWEB)

Azad, Uday Pratap; Ganesan, Vellaichamy, E-mail: velganesh@yahoo.com; Pal, Manas [Banaras Hindu University, Department of Chemistry, Faculty of Science (India)

2011-09-15

Gold nanoparticles (Au NPs) in three different silica based sol-gel matrixes with and without surfactants are prepared. They are characterized by UV-vis absorbance and transmission electron microscopic (TEM) studies. The size and shape of Au NPs varied with the organo-functional group present in the sol-gel matrix. In the presence of mercaptopropyl functionalized organo-silica, large sized (200-280 nm) spherical Au NPs are formed whereas in the presence of aminopropyl functionalized organo-silica small sized (5-15 nm) Au NPs are formed inside the tube like organo-silica. Further, it is found that Au NPs act as efficient catalyst for the reduction of organic dyes. The catalytic rate constant is evaluated from the decrease in absorbance of the dye molecules. Presence of cationic or anionic surfactants greatly influences the catalytic reaction. The other factors like hydrophobicity of the organic dyes, complex formation of the dyes with anionic surfactants, repulsion between dyes and cationic surfactant, adsorption of dyes on the Au NPs also play important role on the reaction rate.

Quantitative detection of RO2 radicals and other products from cyclohexene ozonolysis with ammonium-CI3-TOF and acetate-CI-API-TOF

Science.gov (United States)

Hansel, A.; Scholz, W.; Mentler, B.; Fischer, L.; Berndt, T.

2017-12-01

The performance of the novel ammonium-CI3-TOF utilizing NH4+ adduct ion chemistry to measure quantitatively first generation oxidized product molecules (OMs) as well as highly oxidized organic molecules (HOMs) was investigated for the first time. The gas-phase ozonolysis of cyclohexene served as a test system in order to evaluate the capability of the detection systems. Experiments have been carried out in the TROPOS free-jet flow system at close to atmospheric conditions. Product ion signals were simultaneously observed by the ammonium-CI3-TOF and the acetate-CI-API-TOF. Both instruments are in remarkable good agreement within a factor of two for HOMs. For OMs not containing an OOH group the acetate technique can considerably underestimate OM concentrations by 2-3 orders of magnitude. First steps of cyclohexene ozonolysis generate ten different (m/z product peaks) main products comprising 92% of observed OMs. The remaining 8% are distributed over several (m/z peaks) minor products that can be attributed to HOMs, predominately to highly oxidized RO2 radicals. Summing up, observed ammonium-CI3-TOF products yield 4.9 x 109 molecules cm-³ in excellent agreement with the amount of reacted cyclohexene of 5.0 x 109 molecules cm-³ for reactant concentrations of [O3] = 2.25 x 1012 molecules cm-³ and [cyclohexene] = 2.0 x 1012 molecules cm-³ and a reaction time of 7.9 s. NH4+ adduct ion chemistry based CIMS techniques offer a unique opportunity for complete detection of the whole product distribution, and consequently, for a much better understanding of atmospheric oxidation processes.

Surfactant screening of diesel-contaminated soil

International Nuclear Information System (INIS)

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

1992-01-01

At one installation in California, approximately 60,000 gal of No. 2 diesel fuel leaked into the subsurface environment, resulting in contamination at depths from 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. This paper summarizes a surfactant screening/surfactant flooding research program in which 22 surfactants were screened for their effectiveness in mobilizing the organics from the contaminated soil prior to bioremediation. Anionic surfactants resulted in the greatest degree of diesel mobilization. The most promising surfactants will be employed on contaminated soil samples obtained from the site

A sensitive fluorescent probe for the polar solvation dynamics at protein-surfactant interfaces.

Science.gov (United States)

Singh, Priya; Choudhury, Susobhan; Singha, Subhankar; Jun, Yongwoong; Chakraborty, Sandipan; Sengupta, Jhimli; Das, Ranjan; Ahn, Kyo-Han; Pal, Samir Kumar

2017-05-17

Relaxation dynamics at the surface of biologically important macromolecules is important taking into account their functionality in molecular recognition. Over the years it has been shown that the solvation dynamics of a fluorescent probe at biomolecular surfaces and interfaces account for the relaxation dynamics of polar residues and associated water molecules. However, the sensitivity of the dynamics depends largely on the localization and exposure of the probe. For noncovalent fluorescent probes, localization at the region of interest in addition to surface exposure is an added challenge compared to the covalently attached probes at the biological interfaces. Here we have used a synthesized donor-acceptor type dipolar fluorophore, 6-acetyl-(2-((4-hydroxycyclohexyl)(methyl)amino)naphthalene) (ACYMAN), for the investigation of the solvation dynamics of a model protein-surfactant interface. A significant structural rearrangement of a model histone protein (H1) upon interaction with anionic surfactant sodium dodecyl sulphate (SDS) as revealed from the circular dichroism (CD) studies is nicely corroborated in the solvation dynamics of the probe at the interface. The polarization gated fluorescence anisotropy of the probe compared to that at the SDS micellar surface clearly reveals the localization of the probe at the protein-surfactant interface. We have also compared the sensitivity of ACYMAN with other solvation probes including coumarin 500 (C500) and 4-(dicyanomethylene)-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran (DCM). In comparison to ACYMAN, both C500 and DCM fail to probe the interfacial solvation dynamics of a model protein-surfactant interface. While C500 is found to be delocalized from the protein-surfactant interface, DCM becomes destabilized upon the formation of the interface (protein-surfactant complex). The timescales obtained from this novel probe have also been compared with other femtosecond resolved studies and molecular dynamics simulations.

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

Structure formation in binary mixtures of surfactants: vesicle opening-up to bicelles and octopus-like micelles

Science.gov (United States)

Noguchi, Hiroshi

Micelle formation in binary mixtures of surfactants is studied using a coarse-grained molecular simulation. When a vesicle composed of lipid and detergent types of molecules is ruptured, a disk-shaped micelle, the bicelle, is typically formed. It is found that cup-shaped vesicles and bicelles connected with worm-like micelles are also formed depending on the surfactant ratio and critical micelle concentration. The obtained octopus shape of micelles agree with those observed in the cryo-TEM images reported in [S. Jain and F. S. Bates, Macromol. 37, 1511 (2004).]. Two types of connection structures between the worm-like micelles and the bicelles are revealed.

Nuclear magnetic resonance studies of conformations and molecular interactions in lyotropic mesophases - Applications to solubilization problems

International Nuclear Information System (INIS)

Caniparoli, Jean-Philippe

1988-01-01

After having determined the structural properties of smectic liquid crystals made from double chain surfactants/water binary systems, residual anisotropic interactions and relaxation times measurements were used to investigate the molecular ordering. Phosphorus, deuterium and nitrogen NMR of the surfactant molecules evidenced their high degree of order and the strong anisotropy of their motions. Quantitative results depended on the surfactant polar head -phosphate or ammonium-, while they displayed little variations with the hydrocarbon tail size. The marked dependence of the order and dynamics of small solutes in a lamellar phase on their hydrophilic or hydrophobic behaviour was shown using the same methods. By means of para-magnetically induced relaxation, it was proved that the non-polar solute benzene is located in the organic domain of the liquid crystalline matrix. (author) [fr

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.

Ammonium diamminesilver(I bis(5-chloro-2-hydroxybenzenesulfonate trihydrate

Directory of Open Access Journals (Sweden)

Zhao-Peng Deng

2012-02-01

Full Text Available The reaction of silver nitrate with 5-chloro-2-hydroxybenzenesulfonic acid in the presence of ammonia yielded the title salt, (NH4[Ag(NH32](C6H4ClO4S2·3H2O. The AgI ion shows linear coordination [N—Ag—N = 175.2 (1 °]. The ammonium and diamminesilver cations, the benzenesulfonate anion and the lattice water molecules interact through an intricate network of N—H...O and O—H...O hydrogen bonds to form a three-dimensional network.

Friction mediated by redox-active supramolecular connector molecules.

Science.gov (United States)

Bozna, B L; Blass, J; Albrecht, M; Hausen, F; Wenz, G; Bennewitz, R

2015-10-06

We report on a friction study at the nanometer scale using atomic force microscopy under electrochemical control. Friction arises from the interaction between two surfaces functionalized with cyclodextrin molecules. The interaction is mediated by connector molecules with (ferrocenylmethyl)ammonium end groups forming supramolecular complexes with the cyclodextrin molecules. With ferrocene connector molecules in solution, the friction increases by a factor of up to 12 compared to control experiments without connector molecules. The electrochemical oxidation of ferrocene to ferrocenium causes a decrease in friction owing to the lower stability of ferrocenium-cyclodextrin complex. Upon switching between oxidative and reduction potentials, a change in friction by a factor of 1.2-1.8 is observed. Isothermal titration calorimetry reveals fast dissociation and rebinding kinetics and thus an equilibrium regime for the friction experiments.

Properties of ammonium ion-water clusters: analyses of structure evolution, noncovalent interactions, and temperature and humidity effects.

Science.gov (United States)

Pei, Shi-Tu; Jiang, Shuai; Liu, Yi-Rong; Huang, Teng; Xu, Kang-Ming; Wen, Hui; Zhu, Yu-Peng; Huang, Wei

2015-03-26

Although ammonium ion-water clusters are abundant in the biosphere, some information regarding these clusters, such as their growth route, the influence of temperature and humidity, and the concentrations of various hydrated clusters, is lacking. In this study, theoretical calculations are performed on ammonium ion-water clusters. These theoretical calculations are focused on determining the following characteristics: (1) the pattern of cluster growth; (2) the percentages of clusters of the same size at different temperatures and humidities; (3) the distributions of different isomers for the same size clusters at different temperatures; (4) the relative strengths of the noncovalent interactions for clusters of different sizes. The results suggest that the dipole moment may be very significant for the ammonium ion-water system, and some new stable isomers were found. The nucleation of ammonium ions and water molecules is favorable at low temperatures; thus, the clusters observed at high altitudes might not be present at low altitudes. High humidity can contribute to the formation of large ammonium ion-water clusters, whereas the formation of small clusters may be favorable under low-humidity conditions. The potential energy surfaces (PES) of these different sized clusters are complicated and differ according to the distribution of isomers at different temperatures. Some similar structures are observed between NH4(+)(H2O)n and M(H2O)n (where M represents an alkali metal ion or water molecule); when n = 8, the clusters begin to form the closed-cage geometry. As the cluster size increases, these interactions become progressively weaker. The successive binding energy at the DF-MP2-F12/VDZ-F12 level is better than that at the PW91PW91/6-311++G(3df, 3pd) level and is consistent with the experimentally determined values.

Effects of Aromatic Ammoniums on Methyl Ammonium Lead Iodide Hybrid Perovskite Materials

Directory of Open Access Journals (Sweden)

Jianli Yang

2017-01-01

Full Text Available The introduction of bulky ammoniums into methyl ammonium lead iodide hybrid perovskites (MAPbI3 has emerged as a promising strategy to improve the properties of these materials. In the present work, we studied the effects of several aromatic ammoniums onto the structural, electronic, and optical properties of MAPbI3. Although powder XRD data suggest that the bulky cations are not involved in the bulk phase of the MAPbI3, a surprisingly large effect of the bulky cations onto the photoluminescence properties was observed.

Novel Ammonium Metal Borohydrides

DEFF Research Database (Denmark)

Grinderslev, Jakob; Jepsen, Lars Haahr; Cerny, Radovan

, it cannot store hydrogen reversibly. Recently, the first ammonium metal borohydride, NH4Ca(BH4)3 was published, which may be considered as substitution of K+ by NH4+ in KCa(BH4)3, due to the similar sizes of NH4+ and K+[1]. This compound successfully stabilizes NH4BH4. In the present work, a series of novel...... halide-free ammonium metal borohydrides is presented, which have the chemical compositions (NH4)xM(BH4)n+x. The ammonium metal borohydrides are synthesized by cryomilling of NH4BH4 – M(BH4)n (M = Li, Na, K, Mg, Sr, Y, Mn, La, Gd) in different ratios. A new range of ammonium metal borohydrides is formed......, and the crystal structures and thermal decompositions are investigated. Mixtures of NH4BH4 - NaBH4 do not react, while solid solutions, K1-x(NH4)xBH4, are formed for NH4BH4 - KBH4. For the other composites, novel ammonium metal borohydrides are formed. Several of these structures have been solved from high...

Surfactant-controlled etching of ion track nanopores and its practical applications in membrane technology

International Nuclear Information System (INIS)

Apel, P.Yu.; Blonskaya, I.V.; Dmitriev, S.N.; Mamonova, T.I.; Orelovitch, O.L.; Sartowska, B.; Yamauchi, Yu.

2008-01-01

The effect of surfactants on chemical development of ion tracks in polymers has been studied. It has been shown that surface-active agents added to an alkaline etching solution adsorb on the polymer surface at the pore entrances. This reduces the etch rate, which leads to the formation of pores tapered toward the surface. Self-assembly of surfactant molecules at the pore entrance creates a barrier for their penetration into the etched-out nanopores, whereas hydroxide ions diffuse freely. Due to this, the internal pore volume grows faster than the pore surface diameter. The ability to control pore shape is demonstrated with the fabrication of profiled nano- and micropores in polyethylene terephthalate, polycarbonate. Some earlier published data on small track-etched pores in polycarbonate (in particular, the pore diameter vs. etching time curves measured conductometrically) have been revised in light of the above findings. Adding surfactants to chemical etchants makes it possible to optimize the structure of track membranes, thus improving their retention and permeation properties. Asymmetric membranes with thin skin retention layers have been produced and their performance studied

Surfactant-promoted Prussian Blue-modified carbon electrodes: enhancement of electro-deposition step, stabilization, electrochemical properties and application to lactate microbiosensors for the neurosciences.

Science.gov (United States)

Salazar, P; Martín, M; O'Neill, R D; Roche, R; González-Mora, J L

2012-04-01

We report here for the first time a comparison of the beneficial effects of different cationic surfactants - cetyl trimethyl ammonium bromide (CTAB), benzethonium chloride (BZT) and cetylpyridinium chloride (CPC) - for the electrochemical synthesis of Prussian Blue (PB) films, using cyclic voltammetry (CV), on screen-printed carbon electrodes (SPCEs). Their electrochemical properties were investigated, paying special attention to parameters such as the amount of PB deposited, film thickness, charge transfer rate, permeability, reversibility, stability and sensitivity to hydrogen peroxide detection. All surfactant-enhanced PB-modified SPCEs displayed a significant improvement in their electrochemical properties compared with PB-modified SPCEs formed in the absence of surfactants. Surfactant-modified electrodes displayed a consistently higher PB surface concentration value of 2.1±0.4×10(-8) mol cm(-2) (mean±SD, n=3) indicating that PB deposition efficiency was improved 2-3 fold. K(+) and Na(+) permeability properties of the films were also studied, as were kinetic parameters, such as the surface electron transfer rate constant (k(s)) and the transfer coefficient (α). The hydrogen peroxide sensitivity of surfactant-modified PB films generated by 10 electro-deposition CV cycles gave values of 0.63 A M(-1) cm(-2), which is higher than those reported previously for SPCEs by other authors. Finally, the first lactate microbiosensor described in the literature based on BZT-modified PB-coated carbon fiber electrodes is presented. Its very small cross-section (~10 μm diameter) makes it particularly suitable for neuroscience studies in vivo. Copyright © 2011 Elsevier B.V. All rights reserved.

21 CFR 184.1138 - Ammonium chloride.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ammonium chloride. 184.1138 Section 184.1138 Food... Specific Substances Affirmed as GRAS § 184.1138 Ammonium chloride. (a) Ammonium chloride (NH4Cl, CAS Reg. No. 12125-02-9) is produced by the reaction of sodium chloride and an ammonium salt in solution. The...

Synthesis and characterization of zeolite material from coal ashes modified by surfactant; Sintese e caracterizacao de material zeolitico de cinzas de carvao modificado por surfactante

Energy Technology Data Exchange (ETDEWEB)

Fungaro, D.A., E-mail: dfungaro@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (CQMA/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente; Borrely, S.I. [Instituto de Pesquisas Energeticas e Nucleares (CTR/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Tecnologia das Radiacoes

2010-07-01

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)

Surfactant-free fabrication of fullerene C{sub 60} nanotubules under shear

Energy Technology Data Exchange (ETDEWEB)

Vimalanathan, Kasturi; Raston, Colin L. [Flinders Centre for NanoScale Science Technology (CNST) Chemical and Physical Sciences, Flinders University, Adelaide (Australia); Shrestha, Rekha Goswami [International Centre for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki (Japan); Zhang, Zhi; Zou, Jin [Materials Engineering and Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, QLD (Australia); Nakayama, Tomonobu [International Centre for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki (Japan)

2017-07-10

A method for controlling the self-assembly of fullerene C{sub 60} molecules into nanotubules in the fcc phase, devoid of entrapped solvent, has been established in a thin film microfluidic device. The micron length C{sub 60} nanotubules, with individual hollow diameters of 100 to 400 nm, are formed under continuous flow processing during high shear micromixing of water and a toluene solution of the fullerene, in the absence of surfactant, and without the need for further down-stream processing. TEM revealed pores on the surface of the nanotubes, and the isolated material has a much higher response to small molecule sensing than that for analogous material formed using multistep batch processing. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Nanocrystalline transition metal oxides as catalysts in the thermal decomposition of ammonium perchlorate

Energy Technology Data Exchange (ETDEWEB)

Kapoor, Inder Pal Singh; Srivastava, Pratibha; Singh, Gurdip [Department of Chemistry, DDU Gorakhpur University, Gorakhpur (India)

2009-08-15

Nanocrystalline transition metal oxides (NTMOs) have been successfully prepared by three different methods: novel quick precipitation method (Cr{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}); surfactant mediated method (CuO), and reduction of metal complexes with hydrazine as reducing agent (Mn{sub 2}O{sub 3}). The nano particles have been characterized by X-ray diffraction (XRD) which shows an average particle diameter of 35-54 nm. Their catalytic activity was measured in the thermal decomposition of ammonium perchlorate (AP). AP decomposition undergoes a two step process where the addition of metal oxide nanocrystals led to a shifting of the high temperature decomposition peak toward lower temperature. The kinetics of the thermal decomposition of AP and catalyzed AP has also been evaluated using model fitting and isoconversional method. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Adsorption properties of biologically active derivatives of quaternary ammonium surfactants and their mixtures at aqueous/air interface. I. Equilibrium surface tension, surfactant aggregation and wettability.

Science.gov (United States)

Rojewska, Monika; Biadasz, Andrzej; Kotkowiak, Michał; Olejnik, Anna; Rychlik, Joanna; Dudkowiak, Alina; Prochaska, Krystyna

2013-10-01

The adsorption properties of surfactant mixtures containing two types of quaternary derivatives of lysosomotropic substances: alkyl N,N-dimethylalaninates methobromides and alkyl N,N-dimethylglycinates methobromides were studied. Quantitative and qualitative description of the adsorption process was carried out on the basis of experimentally obtained equilibrium surface tension isotherms. The results indicated that most of the systems studied revealed synergistic effect both in adsorption and wetting properties. In vitro studies on human cancer cells were undertaken and the data obtained showed that the mixtures suppressed the cancer cells' proliferation more effectively than individual components. Results of preliminary research on the interaction of catanionic mixtures with phospholipids suggested a possibility of a strong penetration of cell membranes by the mixtures investigated. Copyright © 2013 Elsevier B.V. All rights reserved.

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.

Surfactant-assisted sol gel preparation of high-surface area mesoporous TiO2 nanocrystalline Li-ion battery anodes

International Nuclear Information System (INIS)

Casino, S.; Di Lupo, F.; Francia, C.; Tuel, A.; Bodoardo, S.; Gerbaldi, C.

2014-01-01

Highlights: • Mesoporous TiO 2 nanocrystalline lithium battery anodes with tunable morphology. • Simple sol–gel technique using different cationic surfactants is adopted. • Textural/morphological characteristics define the electrochemical behaviour. • TiO 2 anatase using C16TAB exhibits stable performance after 200 cycles. • It shows promising prospects as high-voltage safe Li-ion battery anode. - Abstract: We here investigate the physico-chemical/morphological characteristics and cycling behaviour of several kinds of nanocrystalline TiO 2 Li-ion battery anodes selectively prepared through a simple sol–gel strategy based on a low-cost titanium oxysulfate precursor, by mediation of different cationic surfactants having different features (e.g., chain lengths, counter ion, etc.): i.e., cetyl-trimethylammonium bromide (CTAB), cetyl-trimethylammonium chloride (CTAC), benzalkonium chloride (BC) or octadecyl-trimethyl ammonium bromide (C 18 TAB). X-ray diffraction profiles reveal single phase anatase having good correspondence with the reference pattern when using short chain CTAB, while in the other cases the presence of chloride and/or an increased chain length affect the purity of the samples. FESEM analysis reveal nanosized particles forming cauliflower-like aggregates. TiO 2 materials demonstrate mesoporous characteristics and large specific surface area ranging from 250 to 30 m 2 g −1 . Remarkably stable electrode performance are achieved by appropriately selecting the cationic surfactant and the surfactant/precursor ratio. Detailed analysis is provided on the effect of the reaction conditions upon the formation of mesoporous crystalline titania enlightening new directions for the development of high performing lithium storage electrodes by a simple and low cost sol–gel strategy

Novel Ammonium Metal Borohydrides

DEFF Research Database (Denmark)

Grinderslev, Jakob; Jepsen, Lars Haahr; Cerny, Radovan

Ammonium borohydride, NH4BH4, has a very high gravimetric (ρm = 24.5 wt% H2) and volumetric (157.3 g·H2/L) hydrogen content and releases 18.4 wt% H2 below 170 °C. However, NH4BH4 is metastable at RT and ambient pressure, with a half-life of ~6 h. The decomposition is strongly exothermic; therefore......, it cannot store hydrogen reversibly. Recently, the first ammonium metal borohydride, NH4Ca(BH4)3 was published, which may be considered as substitution of K+ by NH4+ in KCa(BH4)3, due to the similar sizes of NH4+ and K+[1]. This compound successfully stabilizes NH4BH4. In the present work, a series of novel...... halide-free ammonium metal borohydrides is presented, which have the chemical compositions (NH4)xM(BH4)n+x. The ammonium metal borohydrides are synthesized by cryomilling of NH4BH4 – M(BH4)n (M = Li, Na, K, Mg, Sr, Y, Mn, La, Gd) in different ratios. A new range of ammonium metal borohydrides is formed...

Reactivity of polyester aliphatic amine surfactants as corrosion inhibitors for carbon steel in formation water (deep well water)

International Nuclear Information System (INIS)

Alsabagh, A.M.; Migahed, M.A.; Awad, Hayam S.

2006-01-01

Effect of different concentrations, 40-200 ppm, of various polyester aliphatic amine surfactants on inhibition of the corrosion of carbon steel in the formation water (deep well water) was investigated. These surfactants exhibit different levels of inhibition particularly at high concentration (200 ppm). Inhibition efficiencies in the range 86-96% were determined by weight loss method. Comparable results were obtained from electrochemical measurements using Tafel extrapolation and polarisation resistance methods. It was shown that all the investigated surfactants act primarily as anodic inhibitors; however, they also affect the rate and mechanism of the cathodic reaction. These compounds function via adsorption on reactive sites on the corroding surface reducing the corrosion rate of the metal. It was revealed that the adsorption of these surfactants obey Langmuir adsorption isotherm. The inhibition effectiveness increases with the length of the aliphatic hydrocarbon chain, being a maximum in the presence of surfactant IV (∼96% efficiency). The corrosion inhibition feature of this compound is attributed to the presence of a long hydrocarbon chain that ensures large surface coverage as well as the presence of multiple active centers for adsorption. Scanning electron microscopy, SEM, has been applied to identify the surface morphology of carbon steel alloy in the absence and presence of the inhibitor molecules

Reactivity of polyester aliphatic amine surfactants as corrosion inhibitors for carbon steel in formation water (deep well water)

Energy Technology Data Exchange (ETDEWEB)

Alsabagh, A.M. [Department of Petroleum Applications, Egyptian Petroleum Research Institute (EPRI), Ahmed El-Zomor Street 1, Nasr City, Cairo 11727 (Egypt); Migahed, M.A. [Department of Petroleum Applications, Egyptian Petroleum Research Institute (EPRI), Ahmed El-Zomor Street 1, Nasr City, Cairo 11727 (Egypt)]. E-mail: mohamedatiyya707@hotmail.com; Awad, Hayam S. [Chemistry Department, Faculty of Girls for Science, Art and Education, Ain Shams University, Asmaa Fahmi Street, Helliopolis, Cairo (Egypt)

2006-04-15

Effect of different concentrations, 40-200 ppm, of various polyester aliphatic amine surfactants on inhibition of the corrosion of carbon steel in the formation water (deep well water) was investigated. These surfactants exhibit different levels of inhibition particularly at high concentration (200 ppm). Inhibition efficiencies in the range 86-96% were determined by weight loss method. Comparable results were obtained from electrochemical measurements using Tafel extrapolation and polarisation resistance methods. It was shown that all the investigated surfactants act primarily as anodic inhibitors; however, they also affect the rate and mechanism of the cathodic reaction. These compounds function via adsorption on reactive sites on the corroding surface reducing the corrosion rate of the metal. It was revealed that the adsorption of these surfactants obey Langmuir adsorption isotherm. The inhibition effectiveness increases with the length of the aliphatic hydrocarbon chain, being a maximum in the presence of surfactant IV ({approx}96% efficiency). The corrosion inhibition feature of this compound is attributed to the presence of a long hydrocarbon chain that ensures large surface coverage as well as the presence of multiple active centers for adsorption. Scanning electron microscopy, SEM, has been applied to identify the surface morphology of carbon steel alloy in the absence and presence of the inhibitor molecules.

Gemini Surfactants Based on Bis-Imidazolium Alkoxy Derivatives as Effective Agents for Delivery of Nucleic Acids: A Structural and Spectroscopic Study.

Directory of Open Access Journals (Sweden)

Zuzanna Pietralik

Full Text Available The success rate of gene therapy depends on the efficient transfection of genetic material into cells. The golden mean between harmlessness and high effectiveness can be provided by synthetic lipid-like molecules that are similar to the components of biological membranes. Cationic gemini surfactants are one such moiety and because of their favourable physicochemical properties (double positive electric charge, reduced toxicity, low values of critical micelle concentration, they show great potential as delivery system components for genetic material in gene therapy. The aim of this study was to investigate the process of the complexation of cationic gemini surfactants with nucleic acids: double-stranded DNA of different sizes (21 bp, ~185 bp, ~20 kbp and siRNA (21 bp. The tested series of dicationic surfactants consists of bis-imidazolium quaternary salts with varying lengths of hydrophobic side chains (m = 5, 6, 7, 8, 9, 11, 12, 14, 16. On the basis of the data obtained by circular dichroism spectroscopy and electrophoresis, we concluded that the studied gemini surfactants with long side chains effectively bind nucleic acids at low concentrations, which leads to the formation of stable lipoplexes. Images obtained by atomic force microscopy also confirmed the formation of vesicular structures, i.e., complexes between DNA and surfactants. The cytotoxicity of selected surfactants was also tested on HeLa cells. The surfactant toxicity significantly depends on surfactant geometry (the length of hydrophobic chain.

Biodegradation of surfactant bearing wastes

International Nuclear Information System (INIS)

Chitra, S.; Chandran, S.; Sasidhar, P.; Lal, K.B.; Amalraj, R.V.

1991-01-01

In nuclear industry, during decontamination of protective wears and contaminated materials, detergents are employed to bring down the level of radioactive contamination within safe limits. However, the surfactant present in these wastes interferes in the chemical treatment process, reducing the decontamination factor. Biodegradation is an efficient and ecologically safe method for surfactant removal. A surfactant degrading culture was isolated and inoculated separately into simulated effluents containing 1% yeast extract and 5-100 ppm sodium lauryl sulphate (SLS) and 1% yeast extract and 5-100 ppm of commercial detergent respectively. The growth of the bacterial culture and the degradation characteristics of the surfactant in the above effluents were monitored under both dynamic and static conditions. (author). 6 refs., 6 figs., 1 tab

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.

Structure and performance of cationic assembly dispersed in amphoteric surfactants solution as a shampoo for hair damaged by coloring.

Science.gov (United States)

Nagahara, Yasuo; Nishida, Yuichi; Isoda, Masanori; Yamagata, Yoshifumi; Nishikawa, Naoki; Takada, Koji

2007-01-01

In recent years, hair coloring gains popularity as a trend of consumer's hair care. This coloring frequently damages hair. In response to this, a new shampoo-base was developed for repairing hair damaged by coloring. The new shampoo-base was prepared by dispersing cationic assembly in a solution of amphoteric surfactants. The mixture of behenyl trimethyl ammonium chloride (C22TAC) and behenyl alcohol (C22OH) was applied as the cationic assembly, which are dispersed in amido propyl betaine laurate (LPB) solution. LPB, which behaves as an amphoteric surfactant, was used as the wash-base. It was verified from the results on the measurements of DSC, calorimeter polarization, cryo-SEM and X-ray diffraction that the cationic assembly has a crystalline structure in the LPB solution. The new shampoo-base was highly efficient to change the color-damaged hair from hydrophilic to hydrophobic. The friction level of the hair washed with the new shampoo-base recovered to the same state as that of healthy hair. The exfoliation of cuticle was reduced after washing with the new shampoo-base.

Facile synthesis of mesostructured ZSM-5 zeolite with enhanced mass transport and catalytic performances

Energy Technology Data Exchange (ETDEWEB)

Li, Chao; Ren, Yanqun [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510641 (China); Gou, Jinsheng [College Material Science and Technology, Beijing Forestry University, Key Laboratory of Wooden Material Science and Application, Ministry of Education, 35 Tsinghua East Road, Haidian District, Beijing 100083 (China); Liu, Baoyu [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510641 (China); Xi, Hongxia, E-mail: cehxxi@scut.edu.cn [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510641 (China)

2017-01-15

Highlights: • A mesostructured MFI zeolite was synthesized via dual-functional surfactant approach. • Mass transport was investigated by applying zero length column technique. • The catalyst exhibited excellent catalytic activity and long lifetime. • Gaussian DFT was employed to study the role of surfactant in crystallization process. - Abstract: A mesostructured ZSM-5 zeolite with multilamellar structure was successfully synthesized by employing a tetra-headgroup rigid bolaform quaternary ammonium surfactant. It was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms, amines temperature programmed desorption (amines-TPD), and computer simulation. These results indicated that the dual-functional amphiphilic surfactants play a critical role for directing the multilamellar structure with high mesoporosity. The mass transport and catalytic performances of the zeolite were investigated by zero length column (ZLC) technique and aldol condensation reactions to evaluate the structure-property relationship. These results clearly indicated that the mass transport of selected molecules in hierarchical zeolite can be accelerated by introducing mesoporous structure with mesostructure with reduced diffusion length and an overall enhanced resistance against deactivation in reactions involving large molecules. Furthermore, the dual-functional surfactant approach of making hierarchical zeolite with MFI nanosheets framework would open up new opportunities for design and synthesis of hierarchical zeolites with controllable mesoporous structures.

Facile synthesis of mesostructured ZSM-5 zeolite with enhanced mass transport and catalytic performances

International Nuclear Information System (INIS)

Li, Chao; Ren, Yanqun; Gou, Jinsheng; Liu, Baoyu; Xi, Hongxia

2017-01-01

Highlights: • A mesostructured MFI zeolite was synthesized via dual-functional surfactant approach. • Mass transport was investigated by applying zero length column technique. • The catalyst exhibited excellent catalytic activity and long lifetime. • Gaussian DFT was employed to study the role of surfactant in crystallization process. - Abstract: A mesostructured ZSM-5 zeolite with multilamellar structure was successfully synthesized by employing a tetra-headgroup rigid bolaform quaternary ammonium surfactant. It was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms, amines temperature programmed desorption (amines-TPD), and computer simulation. These results indicated that the dual-functional amphiphilic surfactants play a critical role for directing the multilamellar structure with high mesoporosity. The mass transport and catalytic performances of the zeolite were investigated by zero length column (ZLC) technique and aldol condensation reactions to evaluate the structure-property relationship. These results clearly indicated that the mass transport of selected molecules in hierarchical zeolite can be accelerated by introducing mesoporous structure with mesostructure with reduced diffusion length and an overall enhanced resistance against deactivation in reactions involving large molecules. Furthermore, the dual-functional surfactant approach of making hierarchical zeolite with MFI nanosheets framework would open up new opportunities for design and synthesis of hierarchical zeolites with controllable mesoporous structures.

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.

Surfactant screening of diesel-contaminated soil

International Nuclear Information System (INIS)

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

1991-01-01

At one installation, approximately 60,000 gal 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 the research program in which 21 surfactants were screened for possible use to mobilize the organics from the contaminated soil prior to bioremediation. Anionic surfactants resulted in the greatest degree of diesel mobilization. The most promising surfactants will be employed on actual contaminated soil samples obtained from the site

Determination of selected quaternary ammonium compounds by liquid chromatography with mass spectrometry. Part II. Application to sediment and sludge samples in Austria

International Nuclear Information System (INIS)

Martinez-Carballo, Elena; Gonzalez-Barreiro, Carmen; Sitka, Andrea; Kreuzinger, Norbert; Scharf, Sigrid; Gans, Oliver

2007-01-01

Soxhlet extraction and high-performance liquid chromatography (HPLC) coupled to tandem mass spectrometry detection (MS/MS) was used for the determination of selected quaternary ammonium compounds (QACs) in solid samples. The method was applied for the determination of alkyl benzyl, dialkyl and trialkyl quaternary ammonium compounds in sediment and sludge samples in Austria. The overall method quantification limits range from 0.6 to 3 μg/kg for sediments and from 2 to 5 μg/kg for sewage sludges. Mean recoveries between 67% and 95% are achieved. In general sediments were especially contaminated by C12 chain benzalkonium chloride (BAC-C12) as well as by the long C-chain dialkyldimethylammonium chloride (DDAC-C18) with a maximum concentration of 3.6 mg/kg and 2.1 mg/kg, respectively. Maxima of 27 mg/kg for DDAC-C10, 25 mg/kg for BAC-C12 and 23 mg/kg for BAC-C14 were determined for sludge samples. The sums of the 12 selected target compounds range from 22 mg/kg to 103 mg/kg in the sludge samples. - The presence of quaternary ammonium surfactants in sediment and sludge samples is reported for the first time in Austria

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

Directory of Open Access Journals (Sweden)

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.

Physico-chemical study of new functionalized surfactants having thermo sensitive de-mixing behaviour: use in extraction of uranyl nitrate

International Nuclear Information System (INIS)

Prevost, S.

2006-04-01

New thermo-sensitive functionalized surfactants with metal-chelating properties have been developed and their physical-chemistry studied. They associate a polyethoxylated nonionic surfactant (CiEj) block and a amino-acid residue as a chelating group. Functionalization preserves both properties of the thermo-sensitive surfactant moiety and the chelating group, a diamide closed to uranyl ionophore.The complexing group participates to the polar head group of the surfactant, increasing the area per molecule. As a result, functionalized surfactants form spherical micelles when diluted in water, and the concentrated part of their phase diagrams exhibits structures having higher curvatures than the nonionic precursor CiEj. The structure of the uranyl - diamide complex has been elucidated by NMR and ESI-MS and is of the type UO 2 (NO 3 ) 2 .L; the associated complexation constant, which is very low, has been evaluated by 1 H NMR.A nitrate salt, LiNO 3 , is added at high concentration to improve complexation. The effect of this salt has been analyzed, and was found to be rather similar to the effect on classical CiEj. When uranyl nitrate complexation occurs, the cloud point decreases dramatically, together with the reduction of the area per head group at micelle/solution interface. This effect can be minimized by using a nonionic precursor having a larger polar head group. The functionalized surfactants have been tested in the cloud point extraction of uranyl nitrate, and have proved their efficiency. Those results demonstrate the viability of the functionalized surfactants design, with a covalent link between a thermo-sensitive surfactant block and a chelating group. (author)

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

Thermal stability and hot-stage Raman spectroscopic study of Ca-montmorillonite modified with different surfactants: A comparative study

International Nuclear Information System (INIS)

Sun, Zhiming; Park, Yuri; Zheng, Shuilin; Ayoko, Godwin A.; Frost, Ray L.

2013-01-01

Highlights: • A typical Ca-montmorillonite was modified with three surfactants through ion exchange. • The organoclays were characterized by XRD, TG and hot stage Raman. • The structural geometry and thermal properties of organoclays were analyzed. • The prepared organoclays show potential prospects in the environmental remediation. - Abstract: Three long chain cationic surfactants were intercalated into Ca-montmorillonite through ion exchange and the obtained organoclays were characterized by X-ray diffraction (XRD), high resolution thermogravimetric analysis (TG) and Raman spectroscopy. The intercalation of surfactants not only changes the surface properties of clay from hydrophilic to hydrophobic but also greatly increases the basal spacing of the interlayers based on XRD analysis. The thermal stability of organoclays intercalated with three surfactants (TTAB, DTAB and CTAB) and the different arrangements of the surfactant molecules intercalated into Ca-montmorillonite were determined by TG-DTG analysis. A Raman spectroscopic study on the Ca-montmorillonite modified by three surfactants prepared at different concentrations provided the detailed conformational ordering of different intercalated long-chain surfactants under different conditions. The wavenumber of the antisymmetric stretching mode is more sensitive than that of the symmetric stretching mode to the mobility of the tail of the amine chain. At room temperature, the conformational ordering is more easily affected by the packing density in the lateral model. With the increase of the temperature, the positions of both the antisymmetric and symmetric stretching bands shift to higher wavenumbers, which indicates a decrease of conformational ordering. This study offers new insights into the structure and properties of Ca-montmorillonite modified with different long chain surfactants. Moreover, the experimental results confirm the potential applications of organic Ca-montmorillonites for the removal

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.

Ammonium generation during SRAT cycle

International Nuclear Information System (INIS)

Hsu, C.W.

1992-01-01

During the IDMS noble-metal demonstration runs ammonium nitrate deposition was found in the vessel vent system of the feed preparation area. In the bench-scale experiments of studying the hydrogen generation during the sludge treatment cycle, ammonium ion production was also monitored. It was found that: During a simulation of the DWPF Cold Chemical Runs SRAT cycle no detectable amount of ammonium ions was generated when treating a non-noble-metal containing sludge simulant according to the nitric acid flowsheet. Ammonium ions were generated during the SRAT-SME cycle when treating the noble-metal containing sludge with either formic acid or nitric acid/late-washing PHA. This is due to the reaction between formic acid and nitrate catalyzed by the noble metals in the sludge simulant. Ammonium ion production closely followed the hydrogen evolution from the catalytic decomposition of formic acid. This report summarizes the results of the production of ammonia during the SRAT cycle

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.

Experimental and QSAR study on the surface activities of alkyl imidazoline surfactants

Science.gov (United States)

Kong, Xiangjun; Qian, Chengduo; Fan, Weiyu; Liang, Zupei

2018-03-01

15 alkyl imidazoline surfactants with different structures were synthesized and their critical micelle concentration (CMC) and surface tension under the CMC (σcmc) in aqueous solution were measured at 298 K. 54 kinds of molecular structure descriptors were selected as independent variables and the quantitative structure-activity relationship (QSAR) between surface activities of alkyl imidazoline and molecular structure were built through the genetic function approximation (GFA) method. Experimental results showed that the maximum surface excess of alkyl imidazoline molecules at the gas-liquid interface increased and the area occupied by each surfactant molecule and the free energies of micellization ΔGm decreased with increasing carbon number (NC) of the hydrophobic chain or decreasing hydrophilicity of counterions, which resulted in a CMC and σcmc decrease, while the log CMC and NC had a linear relationship and a negative correlation. The GFA-QSAR model, which was generated by a training set composed of 13 kinds of alkyl imidazoline though GFA method regression analysis, was highly correlated with predicted values and experimental values of the CMC. The correlation coefficient R was 0.9991, which means high prediction accuracy. The prediction error of 2 kinds of alkyl imidazoline CMCs in the Validation Set that quantitatively analyzed the influence of the alkyl imidazoline molecular structure on the CMC was less than 4%.

Rhamnolipids--next generation surfactants?

Science.gov (United States)

Müller, Markus Michael; Kügler, Johannes H; Henkel, Marius; Gerlitzki, Melanie; Hörmann, Barbara; Pöhnlein, Martin; Syldatk, Christoph; Hausmann, Rudolf

2012-12-31

The demand for bio-based processes and materials in the petrochemical industry has significantly increased during the last decade because of the expected running out of petroleum. This trend can be ascribed to three main causes: (1) the increased use of renewable resources for chemical synthesis of already established product classes, (2) the replacement of chemical synthesis of already established product classes by new biotechnological processes based on renewable resources, and (3) the biotechnological production of new molecules with new features or better performances than already established comparable chemically synthesized products. All three approaches are currently being pursued for surfactant production. Biosurfactants are a very promising and interesting substance class because they are based on renewable resources, sustainable, and biologically degradable. Alkyl polyglycosides are chemically synthesized biosurfactants established on the surfactant market. The first microbiological biosurfactants on the market were sophorolipids. Of all currently known biosurfactants, rhamnolipids have the highest potential for becoming the next generation of biosurfactants introduced on the market. Although the metabolic pathways and genetic regulation of biosynthesis are known qualitatively, the quantitative understanding relevant for bioreactor cultivation is still missing. Additionally, high product titers have been exclusively described with vegetable oil as sole carbon source in combination with Pseudomonas aeruginosa strains. Competitive productivity is still out of reach for heterologous hosts or non-pathogenic natural producer strains. Thus, on the one hand there is a need to gain a deeper understanding of the regulation of rhamnolipid production on process and cellular level during bioreactor cultivations. On the other hand, there is a need for metabolizable renewable substrates, which do not compete with food and feed. A sustainable bioeconomy approach should

Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite.

Science.gov (United States)

Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik

2016-02-01

The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550°C, 5h) and this material has excellent performance as an antibacterial agent after silver ions loading. Copyright © 2015 Elsevier B.V. All rights reserved.

Surfactant-assisted sol gel preparation of high-surface area mesoporous TiO{sub 2} nanocrystalline Li-ion battery anodes

Energy Technology Data Exchange (ETDEWEB)

Casino, S. [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Di Lupo, F., E-mail: francesca.dilupo@polito.it [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Francia, C. [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Tuel, A. [IRCELYON, Institut de Recherches sur la Catalyse et l’environnement de Lyon, UMR 5256, CNRS-Université de Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France); Bodoardo, S. [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Gerbaldi, C., E-mail: claudio.gerbaldi@polito.it [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy)

2014-05-01

Highlights: • Mesoporous TiO{sub 2} nanocrystalline lithium battery anodes with tunable morphology. • Simple sol–gel technique using different cationic surfactants is adopted. • Textural/morphological characteristics define the electrochemical behaviour. • TiO{sub 2} anatase using C16TAB exhibits stable performance after 200 cycles. • It shows promising prospects as high-voltage safe Li-ion battery anode. - Abstract: We here investigate the physico-chemical/morphological characteristics and cycling behaviour of several kinds of nanocrystalline TiO{sub 2} Li-ion battery anodes selectively prepared through a simple sol–gel strategy based on a low-cost titanium oxysulfate precursor, by mediation of different cationic surfactants having different features (e.g., chain lengths, counter ion, etc.): i.e., cetyl-trimethylammonium bromide (CTAB), cetyl-trimethylammonium chloride (CTAC), benzalkonium chloride (BC) or octadecyl-trimethyl ammonium bromide (C{sub 18}TAB). X-ray diffraction profiles reveal single phase anatase having good correspondence with the reference pattern when using short chain CTAB, while in the other cases the presence of chloride and/or an increased chain length affect the purity of the samples. FESEM analysis reveal nanosized particles forming cauliflower-like aggregates. TiO{sub 2} materials demonstrate mesoporous characteristics and large specific surface area ranging from 250 to 30 m{sup 2} g{sup −1}. Remarkably stable electrode performance are achieved by appropriately selecting the cationic surfactant and the surfactant/precursor ratio. Detailed analysis is provided on the effect of the reaction conditions upon the formation of mesoporous crystalline titania enlightening new directions for the development of high performing lithium storage electrodes by a simple and low cost sol–gel strategy.

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 ...

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.

Evidence of ammonium ion-exchange properties of natural bentonite and application to ammonium detection.

Science.gov (United States)

Zazoua, A; Kazane, I; Khedimallah, N; Dernane, C; Errachid, A; Jaffrezic-Renault, N

2013-12-01

Ammonium exchange with hybrid PVC-bentonite (mineral montmorillonite clay) thin film was revealed using FTIR spectroscopy, EDX, cyclic voltammetry and electrochemical impedance spectroscopy. The effect of ammonium exchange on the charge transfer resistance of PVC-bentonite hybrid thin film was attributed to a modification of the intersheet distance and hydration of bentonite crystals. The obtained impedimetric ammonium sensor shows a linear range of detection from 10(-4)M to 1M and a detection limit around 10(-6)M. © 2013.

Solid-State Synthesis and Structure of the Enigmatic Ammonium Octaborate: (NH4)2[B7O9(OH)5]·3/4B(OH)3·5/4H2O.

Science.gov (United States)

Neiner, Doinita; Sevryugina, Yulia V; Schubert, David M

2016-09-06

The compound known since the 19th century as ammonium octaborate was structurally characterized revealing the ammonium salt of the ribbon isomer of the heptaborate anion, [B7O9(OH)5](2-), with boric acid and water molecules. Of composition (NH4)2B7.75O12.63·4.88H2O, it approximates the classical ammonium octaborate composition (NH4)2B8O13·6H2O and has the structural formula {(NH4)2[B7O9(OH)5]}4·3B(OH)3·5H2O. It spontaneously forms at room temperature in solid-state mixtures of ammonium tetraborate and ammonium pentaborate. It crystallizes in the monoclinic space group P21/c with a = 11.4137(2) Å, b = 11.8877(2) Å, c = 23.4459(3) Å, β = 90.092(1)°, V = 3181.19(8) Å(3), and Z = 2 and contains well-ordered ammonium cations and [B7O9(OH)5](2-) anions and disordered B(OH)3 and H2O molecules linked by extensive H bonding. Expeditious solid-state formation of the heptaborate anion under ambient conditions has important implications for development of practical syntheses of industrially useful borates.

Simultaneous determination of naphthol isomers at poly(3-methylthiophene)-nano-Au modified electrode with the enhancement of surfactant

Energy Technology Data Exchange (ETDEWEB)

Li, Linlin [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Shandong Institute for Product Quality Inspection, Jinan 250100 (China); Liu, Enli; Wang, Xiaolin; Chen, Jia [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Zhang, Xiaoli, E-mail: zhangxl@sdu.edu.cn [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

2015-08-01

A polymer film incorporated gold nanoparticle modified electrode was fabricated. The fabricated process involved eletrodeposition of gold nanoparticles and electropolymerization of the 3-methylthiophene (abbreviated 3MT) onto the glassy carbon electrode (GCE). The resulting electrode (P3MT-nano-Au/GCE) was characterized by scanning electron microscopy (SEM), and a simultaneous determination of naphthol isomers at P3MT-nano-Au/GCE was studied using semi-derivative voltammetry. Because of the synergistic effect of gold nanoparticles and poly(3MT), the sensitivity and distinguishability in the simultaneous determination of naphthol isomers were greatly increased. Besides, a further increase in the detecting sensitivity of naphthol isomers could be obtained in the presence of surfactant, cetyl trimethyl ammonium bromide (CTAB). Also, the role of different kinds of surfactants was texted and the action mechanism was discussed in detail. Under the optimal conditions, the linear calibration ranges of the determination of naphthols were 7.0 × 10{sup −7} to 1.5 × 10{sup −4} mol/L for 1-naphthol and 1.0 × 10{sup −6} to 1.5 × 10{sup −4} mol/L for 2-naphthol with detection limits of 1.0 × 10{sup −7} and 3.0 × 10{sup −7} mol/L (S/N = 3), respectively. - Highlights: • Nano-Au-polymer film was fabricated by eletrodeposition and electropolymerization. • Naphthol isomers were detected simultaneously. • Surfactant improved the sensitivity and selectivity.

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

Pilarization TiO2 onto De-oiled spent bleaching clay using Rarasaponin as surfactant

Science.gov (United States)

Hindryawati, N.; Daniel; Erwin; Fadillah, N. D.

2018-03-01

Synthesis and characterization TiO2 pillared deoiled spent bleaching clay (DSBC) with rarasaponin as surfactant had been done. Activation DSBC have been done with H2SO4 1N, followed by pillarization with TiO2 using rarasaponin as surfactant. Characterization has done with Fourier transform infrared spectroscopy showed the rarasaponin as surfactant was successfully carried out in DSBC with the presence of absorption peak C=O stretching group in a sharp 1720.50 cm-1 wavelength range. As well as the C-CH2 stretching uptake peak is represented on wave number 1462.04 cm-1 and 1033,85 cm-1 for aromatic functional group C=C stretching. After pillared by TiO2, the XRD pattern on DSBC showed new peak appears on 2θ = 27,4460° 36,0850° and 55,3216° and the mineral contain on DSBC is rectorite with dioctahedral mica layer and dioctahedral smectite with ratio 2:1. This molecule have formula Na.Al4(Si, Al)8.O20.(OH)4. H2O. Crystallinty of pillared clay showed 72,5014 % after calcination and there is some Ti suspected on the layer based on SEM.

Development of a surfactant liquid membrane extraction process for the cleansing of industrial aqueous effluents containing metallic cation traces

International Nuclear Information System (INIS)

Rapaumbya Akaye, Guy-Roland

1994-01-01

The purpose of this work was to develop a process of surfactant liquid membrane extraction to purify industrial waste solution containing Cu(II), Fe(III), and Zn(II) (about 0,1 g/L). The extractant is the ammonium salt of Cyanex 306 and Aliquat 336. The first part of this work deals with the study of the liquid-liquid extraction of the metals. The efficiency of the extractant has been shown for the extraction of each metal alone and for Cu(II) and Zn(II) in the case of a mixture of the three metals. During this study we have observed that Fe(III) is reduced to Fe(II) (which is not extracted by the salt of Cyanex 301) in presence of Cu(II) and the quaternary ammonium salt (Aliquat 336). The optimisation of the experimental conditions for the discontinuous surfactant liquid membrane process led us to choose the following composition of the emulsion: 1,5 % of Cyanex 301 salt, 2,5 % of ECA 4360, dodecan. The internal phase is an aqueous solution containing 3,5 mol/L of NaOH and 0,5 mol/L tri-ethanolamin The residual concentration of Cu(II) and Zn(II) in the external phase is very low. In the case of iron, only 60 % are extracted because of the reduction phenomenon (10 % in liquid-liquid extraction). The realisation of the continuous process in pulsed column, after optimisation of hydrodynamics conditions, leads to similar results. In stationary conditions, we obtain a raffinate containing less than 0,5 mg/L of Cu(II) and Zn(II) and 36 mg/L of iron. The internal phase contains about 2 g/L of Cu(II) an Zn(II). We tried and minimize the reduction of Fe(III) in surfactant liquid membrane process. Less than 16 % of iron cannot be reduced. This leads to a purification of only 84 % In the basis of these results, processes of purification have been proposed for effluents of various composition. They enable to purify the effluent and besides to concentrate the pollutants about twenty times. (author) [fr

Novel epoxy-benzoxazine water-based emulsions with reactive benzoxazine surfactants for coatings

Directory of Open Access Journals (Sweden)

M. Krajnc

2014-08-01

Full Text Available Novel epoxy-benzoxazine emulsions designed for water-based coatings were prepared and investigated. Bisphenol A-based epoxy resins with molar weights of 340, 377 and 1750 g/mol along with epoxidized soybean oil were emulsified using mono- and bi-functional benzoxazine surfactants, which are able to react with epoxy resins at their cure temperature. The structure of synthesized surfactants carrying one or two polyether chains was confirmed using Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance and differential scanning calorimetry. Stability of emulsions was verified by particle diameters measurements. Coatings, made directly from emulsions, were dried and cured at elevated temperature using 3,3'-dimetoxybenzidine as curing agent to ensure a highly cross-linked structure of thermosetting films. Curing process, thermal properties and hardness of cured films were investigated. It was found that benzoxazine molecules were well incorporated into the epoxy network upon curing, which ensures no void structure of cured copolymer and enhanced coating properties.

Optimalisation of magnesium ammonium phosphate precipitation and its applicability to the removal of ammonium.

Science.gov (United States)

Demeestere, K; Smet, E; Van Langenhove, H; Galbacs, Z

2001-12-01

Among the physico-chemical abatement technologies, mainly acid scrubbers have been used to control NH3-emission. The disadvantage of this technique is that it yields waste water, highly concentrated in ammonia. In this report, the applicability of the magnesium ammonium phosphate (MAP) process to regenerate the liquid phase, produced by scrubbing NH3-loaded waste gases, was investigated. In the MAP process, ammonium is precipitated as magnesium ammonium phosphate, which can be used as a slow release fertilizer. The influence of a number of parameters, e.g. pH, kinetics, molar ratio NH(+)4/Mg2+/PO(3-)4 on the efficiency of the formation of MAP and on the ammonium removal efficiency was investigated. In this way, optimal conditions were determined for the precipitation reaction. Next to this, interference caused by other precipitation reactions was studied. At aqueous NH(+)4-concentrations of about 600 mg l(-1), ammonium removal efficiencies of 97% could be obtained at a molar ratio NH(+)4/Mg2+/PO(3-)4 of 1/1.5/1.5. To obtain this result, the pH was continuously adjusted to a value of 9 during the reaction. According to this study, it is obvious that the MAP-precipitation technology offers opportunities for ammonium removal from scrubbing liquids. The practical applicability of the MAP-process in waste gas treatment systems, however, should be the subject for further investigations.

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.

Glufosinate ammonium selection of transformed Arabidopsis.

Science.gov (United States)

Weigel, Detlef; Glazebrook, Jane

2006-12-01

INTRODUCTIONOne of the most commonly used markers for the selection of transgenic Arabidopsis is resistance to glufosinate ammonium, an herbicide that is sold under a variety of trade names including Basta and Finale. Resistance to glufosinate ammonium is conferred by the bacterial bialophos resistance gene (BAR) encoding the enzyme phosphinotricin acetyl transferase (PAT). This protocol describes the use of glufosinate ammonium to select transformed Arabidopsis plants. The major advantage of glufosinate ammonium selection is that it can be performed on plants growing in soil and does not require the use of sterile techniques.

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 ...

Nighttime oxidation of surfactants at the air-water interface: effects of chain length, head group and saturation

Science.gov (United States)

Sebastiani, Federica; Campbell, Richard A.; Rastogi, Kunal; Pfrang, Christian

2018-03-01

Reactions of the key atmospheric nighttime oxidant NO3 with organic monolayers at the air-water interface are used as proxies for the ageing of organic-coated aqueous aerosols. The surfactant molecules chosen for this study are oleic acid (OA), palmitoleic acid (POA), methyl oleate (MO) and stearic acid (SA) to investigate the effects of chain length, head group and degree of unsaturation on the reaction kinetics and products formed. Fully and partially deuterated surfactants were studied using neutron reflectometry (NR) to determine the reaction kinetics of organic monolayers with NO3 at the air-water interface for the first time. Kinetic modelling allowed us to determine the rate coefficients for the oxidation of OA, POA and MO monolayers to be (2.8±0.7) × 10-8, (2.4±0.5) × 10-8and (3.3±0.6) × 10-8 cm2 molecule-1 s-1 for fitted initial desorption lifetimes of NO3 at the closely packed organic monolayers, τd, NO3, 1, of 8.1±4.0, 16±4.0 and 8.1±3.0 ns, respectively. The approximately doubled desorption lifetime found in the best fit for POA compared to OA and MO is consistent with a more accessible double bond associated with the shorter alkyl chain of POA facilitating initial NO3 attack at the double bond in a closely packed monolayer. The corresponding uptake coefficients for OA, POA and MO were found to be (2.1±0.5) × 10-3, (1.7±0.3) × 10-3 and (2.1±0.4) × 10-3, respectively. For the much slower NO3-initiated oxidation of the saturated surfactant SA we estimated a loss rate of approximately (5±1) × 10-12 cm2 molecule-1 s-1, which we consider to be an upper limit for the reactive loss, and estimated an uptake coefficient of ca. (5±1) × 10-7. Our investigations demonstrate that NO3 will contribute substantially to the processing of unsaturated surfactants at the air-water interface during nighttime given its reactivity is ca. 2 orders of magnitude higher than that of O3. Furthermore, the relative contributions of NO3 and O3 to the oxidative

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

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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.

A study on the interaction of horse heart cytochrome c with some conventional and ionic liquid surfactants probed by ultraviolet-visible and fluorescence spectroscopic techniques

Science.gov (United States)

Mondal, Satyajit; Das, Bijan

2018-06-01

The interactions of a protein cytochrome c with some selected conventional and ionic liquid surfactants have been investigated at pH 7.4 using ultraviolet-visible and fluorescence spectroscopic techniques. We used four conventional surfactants - cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DTAB), sodium N-dodecanoylsarcosinate (SDDS), and N-decanoyl-N-methylglucamine (Mega 10), and a surface active ionic liquid 1-hexadecyl-3-methylimidazolium chloride (C16MeImCl). All the investigated surfactants were found to induce an unfolding of the protein cytochrome c. In presence of CTAB, SDDS and C16MeImCl, the heme iron atom was found to loose methionine from its axial position. Differential binding of the surfactant monomers and their micelles to the protein molecules was inferred. The ionic surfactants were found to be more effective than the nonionic one in unfolding the investigated protein. However, the extent of binding of CTAB/C16MeImCl to cytochrome c reaches a plateau past the critical micellization concentration (cmc) of the surfactant. For each of the cytochrome c-DTAB, cytochrome c-SDDS and cytochrome c-Mega 10 system, although there exists an inflection in the surfactant-binding, saturation point could not be detected. It has been demonstrated from the ultraviolet-visible spectral studies that the oxidation state of iron in cytochrome c does not change when the protein binds with the investigated surfactants.

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)

Mercury Concentration Reduction In Waste Water By Using Liquid Surfactant Membrane Technique

International Nuclear Information System (INIS)

Prayitno; Sardjono, Joko

2000-01-01

The objective of this research is ti know effectiveness of liquid surfactant membrane in diminishing mercury found in waste water. This process can be regarded as transferring process of solved mercury from the external phase functioning as a moving phase to continue to the membrane internal one. The existence of the convection rotation results in the change of the surface pressure on the whole interface parts, so the solved mercury disperses on every interface part. Because of this rotation, the solved mercury will fulfil every space with particles from dispersion phase in accordance with its volume. Therefore, the change of the surface pressure on the whole interface parts can be kept stable to adsorb mercury. The mercury adsorbed in the internal phase moves to dispersed particles through molecule diffusion process. The liquid surfactant membrane technique in which the membrane phase is realized into emulsion contains os kerosene as solvent, sorbitan monoleat (span-80) 5 % (v/v) as surfactant, threbuthyl phosphate (TBP) 10 % (v/v) as extractant, and solved mercury as the internal phase. All of those things are mixed and stirred with 8000 rpm speed for 20 minutes. After the stability of emulsion is formed, the solved mercury is extracted by applying extraction process. The effective condition required to achieve mercury ion recovery utilizing this technique is obtained through extraction and re-extraction process. This process was conducted in 30 minutes with membrane and mercury in scale 1 : 1 on 100 ppm concentration. The results of the processes was 99,6 % efficiency. This high efficiency shows that the liquid surfactant membrane technique is very effective to reduce waste water contamined by mercury

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

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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.

Probing the surface of aqueous surfactant-perfume mixed solutions during perfume evaporation

OpenAIRE

Penfold, J; Thomas, RK; Bradbury, R; Tucker, I; Petkov, JT; Jones, CW; Webster, JRP

2017-01-01

The rate of release or evaporation of perfume molecules from surfaces is a key factor in determining the impact of the perfume in a range of applications relating to home and personal care products. For mixtures of the anionic surfactant sodium dodecylsulfate and the model perfume linalool the rate of change of adsorption with time due to forced air flow over a fixed headspace was evaluated using neutron reflectivity over a period of up to ∼250 min. The measurements were made in the limit of ...

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....

A research on shape-controllable synthesis of Ag3PO4/AgBr and its degradation of ciprofloxacin.

Science.gov (United States)

Chen, Jingran; Yang, Xingyu; Zhu, Chenyu; Xie, Xin; Lin, Cuiping; Zhao, Yalei; Yan, Qishe

2018-03-01

Antibiotic ciprofloxacin is one of the commonly used broad spectrum fluoroquinolone human and veterinary drugs. Because of the overuse of human beings, the presence of ciprofloxacin has been detected in a variety of environmental matrices. To solve this problem, a facile, environmentally-friendly Ag 3 PO 4 /AgBr composite photocatalyst was synthesized by a simple precipitation method at room temperature in the presence of cetyltrimethyl ammonium bromide (CTAB). CTAB was served as surfactant and the source of bromide ions. The as-prepared Ag 3 PO 4 /AgBr microspheres were characterized by means of powder X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-visible diffuse reflectance spectroscopy (UV-vis DRS). The results revealed that the Ag 3 PO 4 /AgBr sample (synthesized with CTAB, 0.8 g) exhibited the highest photocatalytic activity to the photodegradation rate of 96.36%. Moreover, mechanism detection experiment indicated that h + was the major active species in the degradation process. So the enhanced photocatalytic activity of Ag 3 PO 4 /AgBr composites is attributed to its excellent separation of photogenerated electron-hole pairs through Ag 3 PO 4 /AgBr heterojunction. Also, Ag 3 PO 4 /AgBr heterojunction has a lower band gap compared to pure Ag 3 PO 4 and pure AgBr, so higher efficiency of light harvesting is equipped.

Deleted in Malignant Brain Tumors 1 (DMBT1 is present in hyaline membranes and modulates surface tension of surfactant

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Griese Matthias

2007-10-01

Full Text Available Abstract Background Deleted in Malignant Brain Tumors 1 (DMBT1 is a secreted scavenger receptor cysteine-rich protein that binds various bacteria and is thought to participate in innate pulmonary host defense. We hypothesized that pulmonary DMBT1 could contribute to respiratory distress syndrome in neonates by modulating surfactant function. Methods DMBT1 expression was studied by immunohistochemistry and mRNA in situ hybridization in post-mortem lungs of preterm and full-term neonates with pulmonary hyaline membranes. The effect of human recombinant DMBT1 on the function of bovine and porcine surfactant was measured by a capillary surfactometer. DMBT1-levels in tracheal aspirates of ventilated preterm and term infants were determined by ELISA. Results Pulmonary DMBT1 was localized in hyaline membranes during respiratory distress syndrome. In vitro addition of human recombinant DMBT1 to the surfactants increased surface tension in a dose-dependent manner. The DMBT1-mediated effect was reverted by the addition of calcium depending on the surfactant preparation. Conclusion Our data showed pulmonary DMBT1 expression in hyaline membranes during respiratory distress syndrome and demonstrated that DMBT1 increases lung surface tension in vitro. This raises the possibility that DMBT1 could antagonize surfactant supplementation in respiratory distress syndrome and could represent a candidate target molecule for therapeutic intervention in neonatal lung disease.

Multi-technique approach on the interaction between sugar-based surfactant n-dodecyl β-D-maltoside and bovine serum albumin

Energy Technology Data Exchange (ETDEWEB)

Ali, Mohd Sajid, E-mail: smsajidali@gmail.com; Al-Lohedan, Hamad A.

2016-01-15

A multi-technique approach which comprises various basic and advanced techniques, such as surface tensiometry, synchronous, intrinsic and extrinsic fluorescence, far and near-UV circular dichroism (CD), dynamic light scattering (DLS), Fourier transform infra-red (FTIR) and UV–visible spectrophotometries was applied to understand the interaction between biocompatible sugar-based surfactant n-dodecyl β-D-maltoside (C{sub 12}G{sub 2}) and bovine serum albumin (BSA). Formation of complex between surfactant and protein was initially confirmed by surface tension and UV absorption spectroscopy. The presence of BSA shifted the critical micelle concentration of the surfactant at higher concentration and in a similar way the UV spectrum of the BSA was altered by addition of small amount of surfactant. The interfacial properties of the complex such as π{sub cmc} (the surface pressure at the cmc), Γ{sub max} (the maximum surface excess) and A{sub min} (the minimum surface area per molecule) were also calculated. Addition of surfactant causes the quenching of BSA fluorescence and a large blue-shift at both excitation wavelengths (280 and 295 nm) owing to the hydrophobic interaction between surfactant and protein. The quenching took place via static mechanism. Extrinsic fluorescence of 1-anilino-8-naphthalene sulfonate (ANS) increased as a result of the unfolding of the protein. The secondary and tertiary structure of BSA also influenced as revealed by the collective information obtained by far-UV CD, near-UV CD and FTIR spectroscopies. The increase in the size of the complex as a results of the partial unfolding was also confirmed by DLS measurements as well as resonance Rayleigh scattering (RRS). - Highlights: • In the presence of BSA cmc of sugar surfactant n-dodecyl β-D-maltoside increased due to the binding of BSA with surfactant. • The binding of the surfactant leads to the partial unfolding of BSA. • The conformation of BSA predominately remains the α-helical.

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...

Metal ion extractant in microemulsions: where solvent extraction and surfactant science meet

International Nuclear Information System (INIS)

Bauer, C.

2011-01-01

The presented work describes the supramolecular structure of mixtures of a hydrophilic surfactant n-octyl-beta-glucoside (C8G1), and the hydrophobic metal ion extractant tributylphosphate (TBP) in n-dodecane/water as well as in the presence of salts. In the first part, basic solvent extraction system, composed of water, oil and extractant, will be introduced. The focus, however, lies on the extraction of multivalent metal ions from the aqueous phase. During this extraction process and in the following thermodynamic equilibrium, aggregation and phase transition in supramolecular assemblies occur, which are already described in literature. Notably, these reports rest on individual studies and specific conclusions, while a general concept is still missing. We therefore suggest the use of generalized phase diagrams to present the physico-chemical behaviour of (amphiphilic) extractant systems. These phase diagrams facilitated the development of a thermodynamic model based on molecular geometry and packing of the extractant molecules in the oil phase. As a result, we are now in the position to predict size and water content of extractant aggregates and, thus, verify the experimental results by calculation.Consequently, the second part presents a systematic study of the aqueous and organic phase of water/C8G1 and water/oil/TBP mixtures. The focus lies on understanding the interaction between metal ions and both amphiphilic molecules by means of small angle x-ray scattering (SAXS), dynamic light scattering (DLS) and UV-Vis spectroscopy. We confirmed the assumption that extraction of metal ions is driven by TBP, while C8G1 remains passive. In the third and last part, microemulsions of C8G1, TBP, water (and salt) and n-dodecane are characterized by small angle neutron scattering (SANS), and chemical analytics (Karl Fischer, total organic carbon, ICP-OES,...). The co-surfactant behaviour of TBP was highlighted by comparison to the classical n-alcohol (4≤n≤8) co-surfactants

Splash Dynamics of Falling Surfactant-Laden Droplets

Science.gov (United States)

Sulaiman, Nur; Buitrago, Lewis; Pereyra, Eduardo

2017-11-01

Splashing dynamics is a common issue in oil and gas separation technology. In this study, droplet impact of various surfactant concentrations onto solid and liquid surfaces is studied experimentally using a high-speed imaging analysis. Although this area has been widely studied in the past, there is still not a good understanding of the role of surfactant over droplet impact and characterization of resulting splash dynamics. The experiments are conducted using tap water laden with anionic surfactant. The effects of system parameters on a single droplet impingement such as surfactant concentration (no surfactant, below, at and above critical micelle concentration), parent drop diameter (2-5mm), impact velocity and type of impact surface (thin and deep pool) are investigated. Image analysis technique is shown to be an effective technique for identification of coalescence to splashing transition. In addition, daughter droplets size distributions are analyzed qualitatively in the events of splashing. As expected, it is observed that the formation of secondary droplets is affected by the surfactant concentration. A summary of findings will be discussed.

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.

Organometallics and quaternary ammonium salts affect calcium ion desorption from lecithin liposome membranes

International Nuclear Information System (INIS)

Kral, T.E.; Kuczera, J.; Przestalski, S.

2001-01-01

The objective of the present work was to compare the effects of groups of tin and lead organometallic compounds and their mixtures with amphiphilic quaternary ammonium salts (QAS) on the process of calcium ion desorption from lecithin liposome membranes, as dependent on the properties of the hydrophilic and hydrophobic parts of QAS. In the investigations the method of radioactive labels was applied. Synergism and antagonism in the action of both groups of compounds were found. The effectiveness of the cooperation depended more on chain length of QAS compounds than on the size and polarity of their hydrophobic parts. The most effective of all compounds studied was a the mixture of benzyldimethylammonium chloride in a mixture with tripropyltin. Since the rate of calcium desorption proved to be a good measure of efficacy of biologically active surfactants, it seems that the conclusions reached in this paper may be useful for choosing compounds which are able to decontaminate the environment polluted with heavy metals. (orig.)

Producing ammonium chloride from coal or shale

Energy Technology Data Exchange (ETDEWEB)

Christenson, O L

1921-02-25

Process of producing ammonium chloride consists of mixing the substance to be treated with a chloride of an alkali or alkaline earth metal, free silica, water and free hydrochloric acid, heating the mixture until ammonium chloride distills off and collecting the ammonium chloride.

Distribution coefficients of purine alkaloids in water-ammonium sulfate-alkyl acetate-dialkyl phthalate systems

Science.gov (United States)

Korenman, Ya. I.; Krivosheeva, O. A.; Mokshina, N. Ya.

2012-12-01

The distribution of purine alkaloids (caffeine, theobromine, theophylline) was studied in the systems: alkyl acetates-dialkyl phtalate-salting-out agent (ammonium sulfate). The quantitative characteristics of the extraction-distribution coefficients ( D) and the degree of extraction ( R, %) are calculated. The relationships between the distribution coefficients of alkaloids and the length of the hydrocarbon radical in the molecule of alkyl acetate (dialkyl phtalate) are determined. The possibility of predicting the distribution coefficients is demonstrated.

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.

Formation of low charge state ions of synthetic polymers using quaternary ammonium compounds.

Science.gov (United States)

Nasioudis, Andreas; Joyce, William F; van Velde, Jan W; Heeren, Ron M A; van den Brink, Oscar F

2010-07-01

Factors such as high polymer dispersity and variation in elemental composition (of copolymers) often complicate the electrospray ionization mass spectrometry (ESI-MS) analysis of synthetic polymers with high molar mass. In the experiments described in this study, quaternary ammonium compounds were observed to facilitate the production of low charge state pseudomolecular ions when added to the spray solution for ESI-MS. This approach was then used for the ESI time-of-flight mass spectrometry (TOF-MS) analysis of synthetic polymers. Hexadecyltrimethylammonium chloride permitted the successful analysis of poly(ethylene glycol) of 2-40 kDa, poly(propylene glycol) and poly(tetramethylene glycol) oligomers. Increasing the quaternary ammonium compounds' concentration results in the production of low charge state pseudomolecular ions. A comparison of structurally different quaternary ammonium compounds showed that the best performance is expected from large molecules with specific charge localization, which leaves the charge available for interactions. The applicability of the method for the MS analysis of other polymeric systems was also studied. In the case of poly(tetramethylene glycol), the method not only shifted the distributions to higher m/z values but also allowed the detection of high molecular weight material that was not observed without addition of the modifier to the spray solution.

Radiolysis of simple quaternary ammonium salt components of Amberlite resin

International Nuclear Information System (INIS)

Dhiman, Surajdevprakash B.; LaVerne, Jay A.

2013-01-01

The radiation chemical yields of gaseous products, H 2 and CH 4 , in the radiolysis of dry methylammonium chloride, dimethylammonium chloride, trimethylammonium chloride, tetramethylammonium chloride and benzyl trimethylammonium chloride by γ-rays and 5 MeV helium ions have been investigated. Some of these amines are the different components of the quaternary ammonium resin Amberlite, which is a strongly basic anion exchange resin based on a polystyrene divinylbenzene copolymer. Molecular hydrogen yields with γ-radiolysis range from a high of 4.43 molecules per 100 eV for trimethylammonium chloride to 0.07 and 0.05 molecules per 100 eV for tetramethylammonium chloride and benzyl trimethylammonium chloride, respectively. Yields of methane gas are generally negligible except for trimethylammonium chloride and tetramethylammonium chloride, 0.26 and 0.02 molecules per 100 eV, respectively. Isotopic labeling studies suggest that the first step in H 2 production is the breakage of the N-H bond followed by abstraction of H · atom from the methyl groups. EPR analysis shows the formation of both N and C centered radicals. A comparison is made between the radiolysis of Amberlite and its various components

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.

Ammonium nitrate-potassium nitrate system

Energy Technology Data Exchange (ETDEWEB)

Cady, H.H.

1981-01-01

A portion of the binary phase diagram for the system ammonium nitrate-potassium nitrate has been determined from -55/sup 0/C to 185/sup 0/C. Results are presented for the ammonium-nitrate-rich end of the system up to 30 wt% potassium nitrate.

A study on the interaction of horse heart cytochrome c with some conventional and ionic liquid surfactants probed by ultraviolet-visible and fluorescence spectroscopic techniques.

Science.gov (United States)

Mondal, Satyajit; Das, Bijan

2018-06-05

The interactions of a protein cytochrome c with some selected conventional and ionic liquid surfactants have been investigated at pH7.4 using ultraviolet-visible and fluorescence spectroscopic techniques. We used four conventional surfactants - cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DTAB), sodium N-dodecanoylsarcosinate (SDDS), and N-decanoyl-N-methylglucamine (Mega 10), and a surface active ionic liquid 1-hexadecyl-3-methylimidazolium chloride (C 16 MeImCl). All the investigated surfactants were found to induce an unfolding of the protein cytochrome c. In presence of CTAB, SDDS and C 16 MeImCl, the heme iron atom was found to loose methionine from its axial position. Differential binding of the surfactant monomers and their micelles to the protein molecules was inferred. The ionic surfactants were found to be more effective than the nonionic one in unfolding the investigated protein. However, the extent of binding of CTAB/C 16 MeImCl to cytochrome c reaches a plateau past the critical micellization concentration (cmc) of the surfactant. For each of the cytochrome c-DTAB, cytochrome c-SDDS and cytochrome c-Mega 10 system, although there exists an inflection in the surfactant-binding, saturation point could not be detected. It has been demonstrated from the ultraviolet-visible spectral studies that the oxidation state of iron in cytochrome c does not change when the protein binds with the investigated surfactants. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

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)

A novel approach to particle track etching: surfactant enhanced control of pore morphology

International Nuclear Information System (INIS)

Apel', P.Yu.; Dmitriev, S.N.; Vutsadakis, V.A.; Root, D.

2000-01-01

Based on the understanding of the mechanism behind a long observed but thus far unexplained effect, a new method to control the geometry of nano- and micropores is described. Surfactant molecules added to an etching solution used for etching out ion tracks, create a steric-hindrance effect which is responsible for the formation of 'bottleneck' or 'cigar-like' pores. Filtration membranes thus obtained exhibit significantly improved flow rates without deterioration in the retention properties. New applications are made possible with these new pore geometries

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.

Maillard Conjugation of Sodium Alginate to Whey Protein for Enhanced Resistance to Surfactant-Induced Competitive Displacement from Air-Water Interfaces.

Science.gov (United States)

Cai, Bingqing; Saito, Anna; Ikeda, Shinya

2018-01-24

Whey protein adsorbed to an interface forms a viscoelastic interfacial film but is displaced competitively from the interface by a small-molecule surfactant added afterward. The present study evaluated the impact of the covalent conjugation of high- or low-molecular-weight sodium alginate (HA or LA) to whey protein isolate (WPI) via the Maillard reaction on the ability of whey protein to resist surfactant-induced competitive displacement from the air-water interface. Surfactant added after the pre-adsorption of conjugate to the interface increased surface pressure. At a given surface pressure, the WPI-LA conjugate showed a significantly higher interfacial area coverage and lower interfacial film thickness compared to those of the WPI-HA conjugate or unconjugated WPI. The addition of LA to the aqueous phase had little effect on the interfacial area and thickness of pre-adsorbed WPI. These results suggest the importance of the molecular weight of the polysaccharide moiety in determining interfacial properties of whey protein-alginate conjugates.

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.

A vacuum ultraviolet photoionization study on the thermal decomposition of ammonium perchlorate

Science.gov (United States)

Góbi, Sándor; Zhao, Long; Xu, Bo; Ablikim, Utuq; Ahmed, Musahid; Kaiser, Ralf I.

2018-01-01

Pyrolysis products of ammonium perchlorate (NH4ClO4) at 483 K were monitored on line and in situ via single photon photoionization reflectron time-of-flight spectrometry (PI-ReTOF-MS) in the photon energy range of 9.00-17.50 eV. The photoionization efficiency curves (PIE) of the subliming product molecules were collected and allowed for detection of three class of products containing chlorine, nitrogen, and oxygen including atoms and free radicals. These results suggest a new insight into possible low-temperature decomposition pathways of NH4ClO4.

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.

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

Synthesis of Some New Quaternary Ammonium Compounds Evaluation of their Surface properties and Solubilization Activity

International Nuclear Information System (INIS)

Ismail, D.A.; Mohamed, A.S.; Mohamed, M.Z.

2004-01-01

Four cationic surfactants were prepared by condensing fatty acid methyl diethanolamine derivatives (C 6 , C I0 , C I2 , C I8 ) with stoichiometric amounts of trimethyl chlorosilane. The surface properties and parameters were investigated to find the relationship between the structure of the hydrophobic portion of such compounds and their efficiency toward solubilization. The properties studied included surface excess concentration (Γ m ax), critical micelle concentration (cmc). free energy of micellization (ΔG ο m ic) and adsorption (ΔG ο a ds) in addition to the surface tension (γ c mc) at cmc and effectiveness (Π c mc). The values of Γ m ax, ΔG ο mic and ΔG ο a ds were found to increase with increasing number of chain length. while cmc and minimum surface area occupied by one molecule (A m in) were decreased. Solubilization effect of these surfactants on paraffin oil as a non polar solubilizate and biodegradability were studied

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

Spectrophotometric studies of marine surfactants in the southern Baltic Sea

Directory of Open Access Journals (Sweden)

Violetta Drozdowska

2015-04-01

Full Text Available It is well known that surfactants in the southern Baltic Sea constitute the organic matter from riverine waters discharges as well as the secondary degradation products of marine phytoplankton excretion. They reach the surface microlayer by the upwellings and turbulent motions of water and in the membranes of the vesicles as well as from the atmosphere. To assess concentration and spatial distribution of marine surfactants in the southern Baltic Sea, the steady-state spectrophotometric and spectrofluorometric measurements of water samples taken from a surface film and a depth of 0.5 m were carried out. Water samples were collected during windless days of the cruise of r/v ‘Oceania’ in November 2012, from the open and the coastal waters having regard to the vicinity of the Vistula and Łeba mouths. In the present paper, fractions of dissolved organic matter having chromophores (CDOM or fluorophores (FDOM are recognized through their specific spectroscopic behavior, i.e., steady-state absorption, fluorescence excitation and fluorescence spectra. The steady-state spectroscopic measurements revealed the CDOM and FDOM molecules characteristic to both the land and marine origin. Moreover, the concentration and spatial distribution of marine surfactants significantly depend on the distance from the river mouth. Finally, higher values of absorbance and fluorescence intensity observed in a surface film in comparison to these values in a depth of 0.5 m clearly suggest the higher concentration of organic matter in a marine film. On the other hand, our results revealed that a surface microlayer is composed of the same CDOM and FDOM as bulk water.

Characterization and quantitative analysis of surfactants in textile wastewater by liquid chromatography/quadrupole-time-of-flight mass spectrometry.

Science.gov (United States)

González, Susana; Petrović, Mira; Radetic, Maja; Jovancic, Petar; Ilic, Vesna; Barceló, Damià

2008-05-01

A method based on the application of ultra-performance liquid chromatography (UPLC) coupled to hybrid quadrupole-time-of-flight mass spectrometry (QqTOF-MS) with an electrospray (ESI) interface has been developed for the screening and confirmation of several anionic and non-ionic surfactants: linear alkylbenzenesulfonates (LAS), alkylsulfate (AS), alkylethersulfate (AES), dihexyl sulfosuccinate (DHSS), alcohol ethoxylates (AEOs), coconut diethanolamide (CDEA), nonylphenol ethoxylates (NPEOs), and their degradation products (nonylphenol carboxylate (NPEC), octylphenol carboxylate (OPEC), 4-nonylphenol (NP), 4-octylphenol (OP) and NPEO sulfate (NPEO-SO4). The developed methodology permits reliable quantification combined with a high accuracy confirmation based on the accurate mass of the (de)protonated molecules in the TOFMS mode. For further confirmation of the identity of the detected compounds the QqTOF mode was used. Accurate masses of product ions obtained by performing collision-induced dissociation (CID) of the (de)protonated molecules of parent compounds were matched with the ions obtained for a standard solution. The method was applied for the quantitative analysis and high accuracy confirmation of surfactants in complex mixtures in effluents from the textile industry. Positive identification of the target compounds was based on accurate mass measurement of the base peak, at least one product ion and the LC retention time of the analyte compared with that of a standard. The most frequently surfactants found in these textile effluents were NPEO and NPEO-SO4 in concentrations ranging from 0.93 to 5.68 mg/L for NPEO and 0.06 to 4.30 mg/L for NPEO-SO4. AEOs were also identified.

Study of process variables on organophilization of Cubati-PB bentonite clays with ionic surfactants

International Nuclear Information System (INIS)

Silva, C.D. da; Lima, R.C.O.; Costa, J.M.R.; Silva, E.I.A.; Neves, G.A.; Ferreira, H.C.

2012-01-01

The organophilic clays used as agent in the composition dispersed in petroleum drilling fluids, play important roles during drilling. This work aims at the development of several varieties of smectites Cubati-PB for use in drilling fluids for oil with the use of ionic surfactants. We used the following materials: natural bentonite clay Cinza Superior and Verde Superior, from the district of Cubati-PB and ionic quaternary ammonium salt: Praepagen WB®, with 45% active matter. The organoclays were characterized by the laser diffraction, chemical composition by x-ray, differential thermal analysis, thermal gravimetric analysis and x-ray diffraction. Globally found that clays have diffraction and thermal behavior typical of bentonite clay. The results showed showed that the clay used has the potential for application in the process of organophilic and, with respect the process variables has been observed that they do not alter the process organophilization. (author)

Start-up of simultaneous removal of ammonium and sulfate from an anaerobic ammonium oxidation (anammox) process in an anaerobic up-flow bioreactor

Energy Technology Data Exchange (ETDEWEB)

Yang Zhiquan [College of Environmental Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510006 (China); Zhou Shaoqi, E-mail: fesqzhou@scut.edu.cn [College of Environmental Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510006 (China); State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangzhou, Guangdong 510640 (China); Sun Yanbo [College of Environmental Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510006 (China)

2009-09-30

A laboratory testing of simultaneous removal of ammonium and sulfate (SRAS) was studied from an anammox process in an anaerobic bioreactor filled with granular activated carbon. Two different phases of experiment were investigated to start up the SRAS process, and final batch tests were performed to analyze the SRAS process. The experiment included an anammox process and an SRAS process. During the anammox process, the highest removal efficiency of ammonium and nitrite was up to 97 and 98%, respectively. After 160 days in the stationary phase of anammox process, the ratio of ammonium to nitrite consumption was approximately 1:1.15, which is much higher than 1:1.32 in the traditional anammox process. The extra electron acceptor, such as sulfate, was thought to react with ammonium by bacteria. Synthetic wastewater containing ammonium chlorine and sodium sulfate was used as the feed for the bioreactor in the second phase of experiment. During the SRAS process, the influent concentrations of ammonium and sulfate were controlled to be 50-60 and 210-240 mg L{sup -1} respectively. After start-up and acclimatization of this process for 60 days, the average effluent concentrations of ammonium and sulfate were 30 and 160 mg L{sup -1}, respectively. The simultaneous ammonium and sulfate removal was detected in the reactor. In order to further validate the biochemical interaction between ammonium and sulfate, batch tests was carried out. Abiotic tests were carried out to demonstrate that the pure chemical action between ammonium and sulfate without microorganism was not possible. Biotic assays with different ammonium and sulfate concentrations were further investigated that high concentrations of ammonium and sulfate could promote simultaneous removal of ammonium and sulfate. And elemental sulfur and nitrogen gas as the products measured in the SRAS process helped to demonstrate the occurrence of new interaction between nitrogen and sulfur. The new process of SRAS in the

Start-up of simultaneous removal of ammonium and sulfate from an anaerobic ammonium oxidation (anammox) process in an anaerobic up-flow bioreactor

International Nuclear Information System (INIS)

Yang Zhiquan; Zhou Shaoqi; Sun Yanbo

2009-01-01

A laboratory testing of simultaneous removal of ammonium and sulfate (SRAS) was studied from an anammox process in an anaerobic bioreactor filled with granular activated carbon. Two different phases of experiment were investigated to start up the SRAS process, and final batch tests were performed to analyze the SRAS process. The experiment included an anammox process and an SRAS process. During the anammox process, the highest removal efficiency of ammonium and nitrite was up to 97 and 98%, respectively. After 160 days in the stationary phase of anammox process, the ratio of ammonium to nitrite consumption was approximately 1:1.15, which is much higher than 1:1.32 in the traditional anammox process. The extra electron acceptor, such as sulfate, was thought to react with ammonium by bacteria. Synthetic wastewater containing ammonium chlorine and sodium sulfate was used as the feed for the bioreactor in the second phase of experiment. During the SRAS process, the influent concentrations of ammonium and sulfate were controlled to be 50-60 and 210-240 mg L -1 respectively. After start-up and acclimatization of this process for 60 days, the average effluent concentrations of ammonium and sulfate were 30 and 160 mg L -1 , respectively. The simultaneous ammonium and sulfate removal was detected in the reactor. In order to further validate the biochemical interaction between ammonium and sulfate, batch tests was carried out. Abiotic tests were carried out to demonstrate that the pure chemical action between ammonium and sulfate without microorganism was not possible. Biotic assays with different ammonium and sulfate concentrations were further investigated that high concentrations of ammonium and sulfate could promote simultaneous removal of ammonium and sulfate. And elemental sulfur and nitrogen gas as the products measured in the SRAS process helped to demonstrate the occurrence of new interaction between nitrogen and sulfur. The new process of SRAS in the inorganic

Molecular organization and dynamics of micellar phase of polyelectrolyte-surfactant complexes: ESR spin probe study

Science.gov (United States)

Wasserman, A. M.; Kasaikin, V. A.; Zakharova, Yu. A.; Aliev, I. I.; Baranovsky, V. Yu.; Doseva, V.; Yasina, L. L.

2002-04-01

Molecular dynamics and organization of the micellar phase of complexes of linear polyelectrolytes with ionogenic and non-ionogenic surfactants was studied by the ESR spin probe method. Complexes of polyacrylic acid (PAA) and sodium polystyrenesulfonate (PSS) with alkyltrimethylammonium bromides (ATAB), as well as complexes of poly- N, N'-dimethyldiallylammonium chloride (PDACL) with sodium dodecylsulfate (SDS) were studied. The micellar phase of such complexes is highly organized molecular system, molecular ordering of which near the polymeric chain is much higher than in the 'center' of the micelle, it depends on the polymer-detergent interaction, flexibility of polymeric chain and length of carbonic part of the detergent molecule. Complexes of polymethacrylic acid (PMAA) with non-ionic detergent (dodecyl-substituted polyethyleneglycol), show that the local mobility of surfactant in such complexes is significantly lower than in 'free' micelles and depends on the number of micellar particles participating in formation of complexes.

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.

Enhanced transdermal bioavailability of testosterone propionate via surfactant-modified ethosomes

Directory of Open Access Journals (Sweden)

Meng S

2013-08-01

Full Text Available Shu Meng,1 Zaixing Chen,2 Liqun Yang,1 Wei Zhang,1 Danhua Liu,1 Jing Guo,1 Yanmin Guan,1 Jianxin Li11Liaoning Research Institute of Family Planning, Shenyang, Liaoning Province, People's Republic of China; 2School of Pharmacy, China Medical University, Shenyang, Liaoning Province, People's Republic of ChinaAbstract: The current investigation aimed to evaluate the transdermal potential of novel testosterone propionate (TP ethosomes and liposomes prepared by surfactant modification. The effect of hexadecyl trimethyl ammonium bromide and cremophor EL-35 on the particle size and zeta potential of the prepared vesicles was investigated. The entrapment efficiency and stability, as well as in vitro and in vivo skin permeation, were studied with the various techniques, such as differential scanning calorimetry, confocal laser scanning microscopy, transmission electron microscopy, dynamic light scattering, and so on. The results indicated that the ethosomes were defined as spherical, unilamellar structures with low polydispersity (0.100 ± 0.015 and nanometric size (156.5 ± 3.5 nm. The entrapment efficiency of TP in ethosomal and liposomal carriers was 92.7% ± 3.7% and 64.7% ± 2.1%, respectively. The stability profile of the prepared TP ethosomal system assessed for 120 days revealed very low aggregation and very low growth in vesicular size. TP ethosomes also provided an enhanced transdermal flux of 37.85 ± 2.8 µg/cm2/hour and a decreased lag time of 0.18 hours across mouse skin. The skin permeation efficiency of the TP ethosomes as further assessed by confocal laser scanning microscopy revealed enhanced permeation of rhodamine red-loaded formulations to the deeper layers of the skin (260 µm than that of the liposomal formation (120 µm.Keywords: testosterone propionate, surfactant-modified ethosomes, liposomes, confocal laser scanning microscopy

Assessment of primary eye and skin irritants by in vitro cytotoxicity and phototoxicity models: an in vitro approach of new arginine-based surfactant-induced irritation

International Nuclear Information System (INIS)

Benavides, T.; Mitjans, M.; Martinez, V.; Clapes, P.; Infante, M.R.; Clothier, R.H.; Vinardell, M.P.

2004-01-01

Extensive efforts have been made, recently, to find surfactants with lower irritation potential than those presently commercially available, for use in pharmaceutical and cosmetic preparations. Cytotoxic and phototoxic effects of a novel family of dicationic arginine-diglyceride surfactant compounds, 1,2-diacyl,3-O-(L-arginyl)-rac-glycerol with alkyl chain lengths in the range from 8 to 14 carbon atoms, were compared to three commercial surfactants. The end-points used to assess toxicity were the red blood cell lysis assay and uptake of the vital dye neutral red 24 h after dosing (NRU), respectively. Two immortalized cell lines, murine fibroblast cell line, 3T3, and one human keratinocyte cell line, HaCaT, were used as in vitro models to predict the potential phototoxicity which could result in irritation, determined by resazurin reduction to resorufin and neutral red uptake (NRU). All tested surfactants had cytotoxicity effects as demonstrated by and decrease of NR uptake, which showed a clear concentration-response relationship. Concentrations resulting in 50% inhibition of NR uptake (IC 50 ) range from 1 μmol l -1 (hexadecyl trimethyl ammonium bromide) to 565 μmol l -1 (12,12-L-arginine). Erythrocyte haemolysis also showed a clear concentration-response relationship, the 50% of haemolysis ranged from 37 μmol l -1 (10,10-L-arginine) to 151 μmol l -1 (sodium lauryl sulphate). Phototoxicity was performed with 12,12-L-acetyl-arginine, the most stable chemical structure. The validated 3T3 NRU photoxicity assay was used and revealed a phototoxic potential

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

Directory of Open Access Journals (Sweden)

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

Directory of Open Access Journals (Sweden)

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.

Sources et marché du sulfate d'ammonium Sources of and Market for Ammonium Sulfate

Directory of Open Access Journals (Sweden)

Loussouarn C.

2006-11-01

Full Text Available Engrais azoté le plus utilisé dans le monde jusqu'en 1970, le sulfate d'ammonium ne représente plus aujourd'hui que 4 % de la fertilisation azotée. Avec une teneur en azote de 21 % seulement, il a été peu à peu remplacé comme engrais universel par des produits plus concentrés, notamment l'urée et le nitrate d'ammonium. Obtenu pour plus de 40 % comme sous-produit dans la synthèse de monomères comme le caprolactame, l'acrylonitrile ou le méthacrylate de méthyle, et pour près de 10 % dans le traitement des gaz de cokerie, sa production dépend largement des développements du marché des fibres synthétiques, et, dans une moindre mesure, de la sidérurgie et de la métallurgie. Dans les pays développés, où la production est essentiellement fatale, le volume du marché est et sera plus fonction de la disponibilité du sulfate d'ammonium que de la demande ou de facteurs de marché; sa consommation ne résidera plus que dans des applications spécifiques pour lesquelles il sera bien adapté. Par contre, l'intérêt croissant pour compenser le déficit en soufre de certains sols, et les qualités agronomiques propres du sulfate d'ammonium laissent entrevoir la possibilité d'un essor de son utilisation dans certaines régions en voie de développernent. Ammonium sulfate was the most worldwide nitrogenous fertilizer used up to 1970. Today, it makes up only 4% of nitrogenous fertilization. With a nitrogen content of only 21%, it has gradually been replaced as a universal fertilizer by more concentrated products, particularly urea and ammonium nitrate. More than 40% of the ammonium sulfate is obtained as a by-product from the synthesis of monomers such as caprolactam, acrylonitrile or methyl methacrylate, and nearly 10% from coking gas processing. Its production depends extensively on the development of the market for synthetic fibers and, to a lesser extent, on the steel and metallurgical industries. In the industrialized countries

Insertion of liquid crystal molecules into hydrocarbon monolayers

Energy Technology Data Exchange (ETDEWEB)

Popov, Piotr, E-mail: ppopov@kent.edu; Mann, Elizabeth K. [Department of Physics, Kent State University, Kent, Ohio 44242 (United States); Lacks, Daniel J. [Department of Chemical Engineering, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Jákli, Antal [Liquid Crystal Institute, Kent State University, Kent, Ohio 44242-0001 (United States)

2014-08-07

Atomistic molecular dynamics simulations were carried out to investigate the molecular mechanisms of vertical surface alignment of liquid crystals. We study the insertion of nCB (4-Cyano-4{sup ′}-n-biphenyl) molecules with n = 0,…,6 into a bent-core liquid crystal monolayer that was recently found to provide good vertical alignment for liquid crystals. The results suggest a complex-free energy landscape for the liquid crystal within the layer. The preferred insertion direction of the nCB molecules (core or tail first) varies with n, which can be explained by entropic considerations. The role of the dipole moments was found to be negligible. As vertical alignment is the leading form of present day liquid crystal displays (LCD), these results will help guide improvement of the LCD technology, as well as lend insight into the more general problem of insertion of biological and other molecules into lipid and surfactant layers.

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.

Development of technology for ammonium nitrate dissociation process

International Nuclear Information System (INIS)

Zakharkin, B.S.; Varykhanov, V.P.; Kucherenko, V.S.; Solov'yeva, L.N.; Revyakin, V.V.

2000-01-01

Ammonia and ammonium carbonate are frequently used as reagents in fuel production and processing of liquid radioactive wastes. In particular, liquid radioactive wastes that contain ammonium nitrate are generated during operations of metal precipitation. In closed vessels at elevated temperature, for example in evaporators or deposits in tubing, ammonium nitrate may explode due to generation of gaseous nitrogen oxides [2]. In this connection, steps have to be taken to rule out conditions that result in explosion. To do that, ammonium nitrate should be removed even prior to the initial stage of its formation. This report gives results of development of a method of dissociating ammonium nitrate

CISM Course on Fluid Mechanics of Surfactant and Polymer Solutions

CERN Document Server

Ivanov, Ivan

2004-01-01

Colloidal systems and dispersions are of great importance in oil recovery, waist water treatment, coating, food and beverage industry, pharmaceutical industry, medicine, environmental protection etc. Colloidal systems and dispersions are always multi-component and multiphase systems. In these systems at least one dimension is in a range of colloidal forces action: colloidal dispersions/emulsions are examples of three dimensional colloidal systems, while thin liquid films are examples of one dimensional colloidal systems. The contribution presented in this issue deals with flow, distribution and redistribution, coating and deposition of surfactant and polymer molecules in colloidal systems. The book presents reviews of recent advances and trends by well-know scientists and engineers in this area.

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...

Production, characterization, and immobilization of partially purified surfactant-detergent and alkali-thermostable protease from newly isolated Aeromonas caviae.

Science.gov (United States)

Datta, Sumitra; Menon, Gopalakrishnan; Varughese, Bincy

2017-04-21

Proteolytic Aeromonas caviae P-1-1 growing at wide-ranging pH (7.0-11.0) and moderate salinity (0-5% NaCl) was isolated from cattle shed of Thanjavur, India. It produced lipase, gelatinase, and polyhydroxybutyrate. Different culture conditions, incubation time, carbon and nitrogen sources, vitamins, amino acids, surfactants, and metal ions for optimal growth and protease production of P-1-1 were examined. Maximum protease (0.128 U/mL) production was achieved with 1% fructose, 1% yeast extract, 0.1% ammonium sulfate, 3% NaCl, 0.1% CaCl 2  · 2H 2 O, 1% glycine, 0.1% vitamin E, and 0.1% Tween-40 at pH 8.0 after 42 hr of incubation at 37°C. It was active over broad range of pH (7.0-12.0), temperature (15-100°C), and salinity (0-9% NaCl) with optima at pH 10.0, 55°C, and 3% NaCl. It retained 65 and 48% activities at pH 12.0 and 100°C, respectively. Partially purified protease was highly stable (100%) within pH range 7.0-12.0 and salinities of 0-5% NaCl for 48 hr. Cu 2+ , Mn 2+ , Co 2+ , and Ca 2+ did not inhibit its activity. Its stability at extreme pHs, temperatures, and in the presence of surfactants and commercial detergents suggests its possible application in laundry detergents. Partially purified protease was immobilized and reused. This is the first report of alkali-thermotolerant, surfactant-detergent-stable partially purified extracellular protease from A. caviae.

One-step synthesis, wettability and foaming properties of high-performance non-ionic hydro-fluorocarbon hybrid surfactants

Science.gov (United States)

Peng, Ying-ying; Lu, Feng; Tong, Qing-Xiao

2018-03-01

In this work, a series of non-ionic hydro-fluorocarbon hybrid surfactants (C9F19CONH(CH2)3N(CmH2m+1)2, abbreviated as C9F19AM (m = 1), C9F19AE (m = 2) and C9F19AB (m = 4) were easily synthesized by one-step reaction and characterized by 1HNMR, 19FNMR and MS spectroscopy. Unlike conventional non-ionic surfactants (most hydrophilic units consisted of hydroxy or ether groups), their hydrophilic groups were composed of amide group, an eco-friendly unit. The surface activity, wettability, thermal stability and foaming performance were investigated. The results showed that the C9F19AE (C9F19CONH(CH2)3N[CH2CH3]2) had superior surface and interface activities, which could reduce the surface tension of water down to 15.37 mN/m and the interfacial tension (cyclohexane/water/surfactants) to 5.8 mN/m with a low cmc (critical micelle concentration) of 0.12 mmol/L. Through the calculation of Amin (the minimum area occupied per-surfactant molecule), we speculated this higher surface activity was related to the compatibility between hydrocarbon and fluorocarbon chains. When used as wetting and foaming agents, the C9F19AE also outperformed great advantages over conventional non-ionic fluorocarbon and hydrocarbon surfactants, which could decrease the contact angle of water on PTFE plate from 107.7° to 3.6°, and increase the foam integrated value F to 536 500 ± 3066.5 mL s. Moreover, the decomposition temperature (Td) of C9F19AE could reach up to 173 °C. This work demonstrates a valuable strategy to develop a kind of high-efficiency foaming agent via facile synthesis.

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.

Controlling the capture and release of DNA with a dual-responsive cationic surfactant.

Science.gov (United States)

Xu, Lu; Feng, Lei; Hao, Jingcheng; Dong, Shuli

2015-04-29

A dual-responsive cationic surfactant, 4-ethoxy-4'-(trimethyl- aminoethoxy) azobenzene trichloromonobromoferrate (azoTAFe), which contains both a light-responsive moiety azobenzene and a paramagnetic counterion, [FeCl3Br](-), was designed and synthesized. Not only does this cationic surfactant abundantly utilize inexhaustible and clean sources, i.e., light and magnetic field, but it also serves as a powerful dual-switch molecule for effectively controlling the capture and release of DNA. Our results could provide potential applications in gene therapy for creating smart and versatile machines to control the transport and delivery of DNA more intelligently and robustly. It was proved that the light switch can independently realize a reversible DNA compaction. The introduction of a magnetic switch can significantly enhance the compaction efficiency, help compact DNA with a lower dosage and achieve a magnetic field-based targeted transport of DNA. In addition, the light switch can make up the irreversibility of magnetic switch. This kind of self-complementation makes the cationic azoTAFe be useful as a potential tool that can be applied to the field of gene therapy and nanomedicine.

Surfactant protein D is proatherogenic in mice

DEFF Research Database (Denmark)

Sorensen, Grith L; Madsen, Jens; Kejling, Karin

2006-01-01

Surfactant protein D (SP-D) is an important innate immune defense molecule that mediates clearance of pathogens and modulates the inflammatory response. Moreover, SP-D is involved in lipid homeostasis, and pulmonary accumulation of phospholipids has previously been observed in SP-D-deficient (Spd......-/-) mice. Atherogenesis involves both inflammation and lipid deposition, and we investigated the role of SP-D in the development of atherosclerosis. SP-D synthesis was localized to vascular endothelial cells. Atherosclerotic lesion areas were 5.6-fold smaller in the aortic roots in Spd-/- mice compared...... with wild-type C57BL/6N mice on an atherogenic diet. HDL cholesterol (HDL-C) was significantly elevated in Spd-/- mice. Treatment of Spd-/- mice with a recombinant fragment of human SP-D resulted in decreases of HDL-C (21%) as well as total cholesterol (26%), and LDL cholesterol (28%). Plasma TNF...

Spectrometric determination of ammonium-nitrogen with quinol in ...

African Journals Online (AJOL)

Quinol is proposed as a reagent for the spectrometric determination of ammonium-nitrogen (NH4+-N) in aqueous medium. Quinol forms a pink complex with ammonium salt in aqueous medium. Hydrogen peroxide is needed for colour accentuation. The quinol/ammonium charge transfer complex has absorption maximum ...

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.

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.

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

Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

International Nuclear Information System (INIS)

Voisin, David

2002-01-01

Oppositely charged surfactant and polyelectrolyte are present in hair shampoos and conditioners, together with particles (e.g. anti-dandruff agents for scalp) and droplets (e.g. silicone oil for the hair). These are normally formulated at high surfactant concentrations, beyond the flocculation region for the polyelectrolyte concentration used. However, on dilution with water, during application, flocs are formed which carry the particles and droplets to the scalp and hair. The addition of an anionic surfactant to an aqueous solution of cationic polyelectrolyte, at a given concentration, can lead to the formation of polyelectrolyte-surfactant 'particles', in which the surfactant 'binds' to the polyelectrolyte. This occurs from the critical association concentration (CAC), up to the surfactant concentration corresponding to maximum binding. Within this range of surfactant concentrations, the surfactant bound to the polyelectrolyte is thought to associate to form what might be termed 'internal micelles'. Each polyelectrolyte-surfactant particle in the region of the CAC, and just beyond, contains many polyelectrolyte chains, held together essentially by micelle bridges. These particles, however, remain net positively charged, and therefore stable. At the other end of the binding range of the surfactant, so many internal micelles are present that the polymer-surfactant particles are now net negatively charged. Indeed binding stops since no further micelles can be accommodated. Again, the particles are stable. However, there exists a range of surfactant concentrations, lying within the range referred to above, where the net charge is reduced sufficiently that the polymer-surfactant particles will flocculate to form much larger structures. The onset of this second range might be termed the 'critical flocculation concentration' (CFC), and the end, the 'critical stabilisation concentration' (CSC). In this work, the CFC and the CSC have been determined for mixtures of

Synthesis and characterization of zeolite from coal ashes modified by cationic surfactant; Sintese e caracterizacao de zeolita de cinzas de carvao modificada por surfactante cationico

Energy Technology Data Exchange (ETDEWEB)

Fungaro, D.A.; Borrely, S.I., E-mail: dfungaro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2012-01-15

Zeolite synthesized from coal fly ash was modified with different concentrations (2 and 20 mmol.L{sup -1}) of hexadecyltrimethylammonium bromide (HDTMA-Br). The Non-Modified Zeolite (NMZ) and Surfactant-Modified Zeolites (SMZ) were characterized by X-ray fluorescence spectrometry, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, thermogravimetric analysis, among others. The SMS presented negative charge probably due to the formation of a partial bilayer of HDTMA on exchangeable active sites on the external surface of NMZ. A decrease in surface area was observed for SMZ as compared to NMZ indicating zeolite surface coverage with HDTMA-Br molecules. The crystalline nature of the zeolite remained intact after adsorption of surfactant and heating for drying. FTIR analysis indicated that there were no significant changes in the structure of the zeolite after adsorption of surfactant. (author)

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

Influence of the Surfactant Nature on the Occurrence of Self-Assembly between Rubber Particles and Thermally Reduced Graphite Oxide during the Preparation of Natural Rubber Nanocomposites

Directory of Open Access Journals (Sweden)

Héctor Aguilar-Bolados

2015-01-01

Full Text Available The natural rubber (NR latex consists of polymer particles charged negatively due to the adsorbed phospholipids and proteins molecules. The addition of stable aqueous suspension of thermally reduced graphite oxide (TRGO stabilized by ionic surfactants to NR latex can favor the occurrence of interaction between the stabilized TRGO and NR particles. Herein, the use of two surfactants of different nature, namely, sodium dodecyl sulfate (SDS and dodecyltrimethylammonium bromide (DTAB, for the preparation of (TRGO/NR nanocomposites, is reported. Zeta potential and particle size measurements indicated that the use of DTAB as cationic surfactant results in the flocculation of NR particles and promoted the formation of ion-pair interactions between TRGO and the proteins and/or phospholipids present on the NR surface. This indicates that the use of DTAB can promote a self-assembly phenomenon between TRGO with adsorbed DTAB molecules and NR particles. The occurrence of self-assembly phenomenon allows obtaining homogenous dispersion of TRGO particles in the polymer matrix. The TRGO/NR nanocomposites prepared by the use of DTAB exhibited superior mechanical properties and excellent electrical conductivities reaching values of stress at 500% strain of 3.02 MPa and 10−4 S/cm, respectively.

Linking surfactant protein SP-D and IL-13

DEFF Research Database (Denmark)

Qaseem, Asif S; Sonar, Sanchaita; Mahajan, Lakshna

2012-01-01

of allergen-IgE interaction, histamine release by sensitised mast cells, downregulation of specific IgE production, suppression of pulmonary and peripheral eosinophilia, inhibition of mechanisms that cause airway remodelling, and induction of apoptosis in sensitised eosinophils. SP-D can also shift helper T......Surfactant protein D (SP-D) is an innate immune molecule that plays a protective role against lung infection, allergy, asthma and inflammation. In vivo experiments with murine models have shown that SP-D can protect against allergic challenge via a range of mechanisms including inhibition...... cell polarisation following in vivo allergenic challenge, from pathogenic Th2 to a protective Th1 cytokine response. Interestingly, SP-D gene deficient (-/-) mice show an IL-13 over-expressing phenotype. IL-13 has been shown to be involved in the development of asthma. Transgenic mice over...

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.

Synthetic high-charge organomica: effect of the layer charge and alkyl chain length on the structure of the adsorbed surfactants.

Science.gov (United States)

Pazos, M Carolina; Castro, Miguel A; Orta, M Mar; Pavón, Esperanza; Valencia Rios, Jesús S; Alba, María D

2012-05-15

A family of organomicas was synthesized using synthetic swelling micas with high layer charge (Na(n)Si(8-n)Al(n)Mg(6)F(4)O(20)·XH(2)O, where n = 2, 3, and 4) exchanged with dodecylammonium and octadecylammonium cations. The molecular arrangement of the surfactant was elucidated on the basis on XRD patterns and DTA. The ordering conformation of the surfactant molecules into the interlayer space of micas was investigated by (13)C, (27)Al, and (29)Si MAS NMR. The arrangement of alkylammonium ions in these high-charge synthetic micas depends on the combined effects of the layer charge of the mica and the chain length of the cation. In the organomicas with dodecylammonium, a transition from a parallel layer to a bilayer-paraffin arrangement is observed when the layer charge of the mica increases. However, when octadecylammonium is the interlayer cation, the molecular arrangement of the surfactant was found to follow the bilayer-paraffin model for all values of layer charge. The amount of ordered conformation all-trans is directly proportional of layer charge.

Enhanced solubilization of curcumin in mixed surfactant vesicles.

Science.gov (United States)

Kumar, Arun; Kaur, Gurpreet; Kansal, S K; Chaudhary, Ganga Ram; Mehta, S K

2016-05-15

Self-assemblies of equimolar double and single chain mixed ionic surfactants, with increasing numbers of carbon atoms of double chain surfactant, were analyzed on the basis of fluorescence and conductivity results. Attempts were also made to enhance the solubilization of curcumin in aqueous equimolar mixed surfactant systems. Mixed surfactant assembly was successful in retarding the degradation of curcumin in alkaline media (only 25-28 40% degraded in 10h at pH 13). Fluorescence spectroscopy and fluorescence quenching methods were employed to predict the binding position and mechanism of curcumin with self-assemblies. Results indicate that the interactions take place according to both dynamic and static quenching mechanisms and curcumin was distributed in a palisade layer of mixed aggregates. Antioxidant activity (using DPPH radical) and biocompatibility (using calf-thymus DNA) of curcumin-loaded mixed surfactant formulations were also evaluated. The prepared systems improved the stability, solubility and antioxidant activity of curcumin and additionally are biocompatible. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ion-selective solid-phase electrode sensitive to ammonium ions

International Nuclear Information System (INIS)

Vlasov, Yu.G.; Milonova, M.S.; Antonov, P.P.; Bychkov, E.A.; Ehfa, A.Ya.

1983-01-01

Ammonium phosphomolybdate is investigated for the purpose of using it as membrane material of ammonium-selective solid-phase electrodes. Estimation of proton mobility and ion conductivity of ammonium phosphomolybdate is performed

In vitro disintegration of goat brain cystatin fibrils using conventional and gemini surfactants: Putative therapeutic intervention in amyloidoses.

Science.gov (United States)

Bhat, Waseem Feeroze; Bhat, Imtiyaz Ahmad; Bhat, Sheraz Ahmad; Bano, Bilqees

2016-12-01

Many protein misfolding diseases in mammalian system are characterised by the accumulation of protein aggregates in amyloid fibrillar forms. Several therapeutic approaches include reduction in the production of the amyloidogenic form of proteins, increase in the clearance rate of misfolded or aggregated proteins, and direct inhibition of the self-assembly process have been explained. One of the possible remedial treatments for such disorders may be to identify molecules which are capable of either preventing formation of fibrils or disintegrating the formed fibrils. In this work, we have studied the effect of conventional surfactants; sodium dodecylsulphate (SDS), cetyl trimethylammonium bromide (CTAB) and dicationic gemini (16-4-16) surfactant on the disintegration of the goat brain cystatin (GBC) fibrils above their critical micelle concentrations (CMC) using ThT fluorescence, CD, TEM, Congo red and turbidity approaches. The results obtained are significant and showing the best disintegrating potency on GBC fibrils with gemini surfactant. The outcome from this work will aid in the development and/or design of potential inhibitory agents against amyloid deposits associated with amyloid diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

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+ ...

Atmospheric behaviour of ammonia and ammonium

NARCIS (Netherlands)

Asman, W.A.H.

1987-01-01

1.4.1 Scope of this thesis

A few models for ammonia and ammonium exist. Russell et al. (1983) made a multi-layer Lagrangian transport model describing the transport and formation of ammonium nitrate aerosol for California. They did not take reactions of ammonia and sulphuric acid

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.

Electrolytic treatment of liquid waste containing ammonium nitrate

International Nuclear Information System (INIS)

Komori, R.; Ogawa, N.; Ohtsuka, K.; Ohuchi, J.

1981-01-01

A study was made on the safe decomposition of ammonium nitrate, which is the main component of α-liquid waste from plutonium fuel facilities, by means of electrolytic reduction and thermal decomposition. In the first stage, ammonium nitrate is reduced to ammonium nitrite by electrolytic reduction using an electrolyser with a cation exchange membrane as a diaphragm. In the second stage, ammonium nitrite is decomposed to N 2 and H 2 O. The alkaline region and a low temperature are preferable for electrolytic reduction and the acidic region and high temperature for thermal decomposition. A basis was established for an ammonium nitrate treatment system in aqueous solution through the operation of a bench-scale unit, and the operating data obtained was applied to the basic design of a 10-m 3 /a facility. (author)

Decomposition of ammonium nitrate in homogeneous and catalytic denitration

International Nuclear Information System (INIS)

Anan'ev, A. V.; Tananaev, I. G.; Shilov, V. P.

2005-01-01

Ammonium nitrate is one of potentially explosive by-products of spent fuel reprocessing. Decomposition of ammonium nitrate in the HNO 3 -HCOOH system was studied in the presence or absence of Pt/SiO 2 catalyst. It was found that decomposition of ammonium nitrate is due to homogeneous noncatalytic oxidation of ammonium ion with nitrous acid generated in the HNO 3 -HCOOH system during denitration. The platinum catalyst initiates the reaction of HNO 3 with HCOOH to form HNO 2 . The regular trends were revealed and the optimal conditions of decomposition of ammonium nitrate in nitric acid solutions were found [ru

Optimization of nutritional requirements and ammonium feeding ...

African Journals Online (AJOL)

tounukarin

2011-09-07

Sep 7, 2011 ... Statistical experiment design and data analysis were used to ... Ammonium control strategies in fed-batch fermentation showed that when ammonium concentration ... environments, combined with the real-time process para-.

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.

Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

Energy Technology Data Exchange (ETDEWEB)

Voisin, David

2002-07-01

Oppositely charged surfactant and polyelectrolyte are present in hair shampoos and conditioners, together with particles (e.g. anti-dandruff agents for scalp) and droplets (e.g. silicone oil for the hair). These are normally formulated at high surfactant concentrations, beyond the flocculation region for the polyelectrolyte concentration used. However, on dilution with water, during application, flocs are formed which carry the particles and droplets to the scalp and hair. The addition of an anionic surfactant to an aqueous solution of cationic polyelectrolyte, at a given concentration, can lead to the formation of polyelectrolyte-surfactant 'particles', in which the surfactant 'binds' to the polyelectrolyte. This occurs from the critical association concentration (CAC), up to the surfactant concentration corresponding to maximum binding. Within this range of surfactant concentrations, the surfactant bound to the polyelectrolyte is thought to associate to form what might be termed 'internal micelles'. Each polyelectrolyte-surfactant particle in the region of the CAC, and just beyond, contains many polyelectrolyte chains, held together essentially by micelle bridges. These particles, however, remain net positively charged, and therefore stable. At the other end of the binding range of the surfactant, so many internal micelles are present that the polymer-surfactant particles are now net negatively charged. Indeed binding stops since no further micelles can be accommodated. Again, the particles are stable. However, there exists a range of surfactant concentrations, lying within the range referred to above, where the net charge is reduced sufficiently that the polymer-surfactant particles will flocculate to form much larger structures. The onset of this second range might be termed the 'critical flocculation concentration' (CFC), and the end, the 'critical stabilisation concentration' (CSC). In this work, the CFC and