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Sample records for surfactant concentrations dsc

  1. Effects of Concentration and Conformation of Surfactants on Phase Separation of Surfactant-Water-Oil Systems

    Institute of Scientific and Technical Information of China (English)

    袁银权; 邹宪武; 刘昊阳

    2004-01-01

    The effects of surfactants on the phase separation of surfactant-water-oil systems have been investigated by using discontinuous molecular dynamic simulations. The phase separation speed and equilibrium configuration are dependent on the surfactant concentration and conformation. The equilibrium concentration of surfactants at the interface remains constant. With the increasing surfactant concentration, the equilibrium configuration crosses over from the disperse phase to the bicontinuous one. The crossover concentration is estimated. The conformation of the surfactant has little effect on the equilibrium concentration of surfactants at the interface,while it affects the equilibrium configuration after phase separation.

  2. Influence of surfactant concentration on nanohydroxyapatite growth

    Indian Academy of Sciences (India)

    D Gopi; J Indira; S Nithiya; L Kavitha; U Kamachi Mudali; K Kanimozhi

    2013-10-01

    Nanohydroxyapatite particles with different morphologies were synthesized through a microwave coupled hydrothermal method using CTAB as a template. A successful synthesis of nanosized HAP spheres, rods and fibres is achieved through this method by controlling the concentration of the surfactant. The concentration of the surfactant was tuned in such a way that the desired HAP nanostructures were obtained. The resultant powders were sintered at 900 °C in order to obtain phase pure HAP particles. The results obtained by Fourier transform infrared spectroscopy (FT–IR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques have substantiated the formation of nanosized HAP spheres and fibres.

  3. Factors influencing the crystallisation of highly concentrated water-in-oil emulsions: A DSC study

    Directory of Open Access Journals (Sweden)

    Irina Masalova

    2012-03-01

    Full Text Available Highly concentrated emulsions are used in a variety of applications, including the cosmetics, food and liquid explosives industries. The stability of these highly concentrated water-in-oil emulsions was studied by differential scanning calorimetry. Crystallisation of the emulsions was initiated by exposing the emulsions to a low temperature. The effects of surfactant type, electrolyte concentration and electrolyte composition in the aqueous phase on emulsion crystallisation temperature were studied. Surfactant type affected the emulsion crystallisation temperature in the following order: PIBSA-MEA=PIBSA-UREA < PIBSA-MEA/SMO < PIBSA-IMIDE < SMO. These results are in the same sequence as results obtained for the stability of these emulsions in aging studies, that is, PIBSA-MEA was the most stable with age and SMO was the least. The effect of the surfactant type on emulsion crystallisation can probably be attributed to the differing strengths of the surfactant–electrolyte interactions, which result in different molecular packing geometry and differing mobility of the surfactant lipophilic portion at the interface. These results enhance our understanding of the factors that affect the stability of explosive emulsions.

  4. High Oxygen Concentrations Adversely Affect the Performance of Pulmonary Surfactant.

    Science.gov (United States)

    Smallwood, Craig D; Boloori-Zadeh, Parnian; Silva, Maricris R; Gouldstone, Andrew

    2017-08-01

    Although effective in the neonatal population, exogenous pulmonary surfactant has not demonstrated a benefit in pediatric and adult subjects with hypoxic lung injury despite a sound physiologic rationale. Importantly, neonatal surfactant replacement therapy is administered in conjunction with low fractional FIO2 while pediatric/adult therapy is administered with high FIO2 . We suspected a connection between FIO2 and surfactant performance. Therefore, we sought to assess a possible mechanism by which the activity of pulmonary surfactant is adversely affected by direct oxygen exposure in in vitro experiments. The mechanical performance of pulmonary surfactant was evaluated using 2 methods. First, Langmuir-Wilhelmy balance was utilized to study the reduction in surface area (δA) of surfactant to achieve a low bound value of surface tension after repeated compression and expansion cycles. Second, dynamic light scattering was utilized to measure the size of pulmonary surfactant particles in aqueous suspension. For both experiments, comparisons were made between surfactant exposed to 21% and 100% oxygen. The δA of surfactant was 21.1 ± 2.0% and 35.8 ± 2.0% during exposure to 21% and 100% oxygen, respectively (P = .02). Furthermore, dynamic light-scattering experiments revealed a micelle diameter of 336.0 ± 12.5 μm and 280.2 ± 11.0 μm in 21% and 100% oxygen, respectively (P < .001), corresponding to a ∼16% decrease in micelle diameter following exposure to 100% oxygen. The characteristics of pulmonary surfactant were adversely affected by short-term exposure to oxygen. Specifically, surface tension studies revealed that short-term exposure of surfactant film to high concentrations of oxygen expedited the frangibility of pulmonary surfactant, as shown with the δA. This suggests that reductions in pulmonary compliance and associated adverse effects could begin to take effect in a very short period of time. If these findings can be demonstrated in vivo, a role for

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

    National Research Council Canada - National Science Library

    Hassan, A K

    2015-01-01

    ...°. Applying the simple linear regression least squares method statistical analysis to the temperature-conductivity obtained data determines the effective surfactants blend concentration required...

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

    Science.gov (United States)

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

    2010-12-01

    The stability against coalescence of O/W emulsions in the presence of both surfactants and colloidal particles was investigated. In particular the effect of the surfactant type and concentration in these emulsifier mixtures on the O/W emulsions' stability was studied. Two types of surfactants were selected; those that have the ability to stabilise O/W emulsions on their own (O/W surfactants) and those that cannot (W/O surfactants). Tween 60 and Sodium Caseinate were selected as the O/W surfactants and lecithin as the W/O surfactant. Oil-in-water emulsions prepared with both particles and any of the three surfactants were stable against coalescence but, depending on the type of surfactant, the behaviour of the systems was found to depend on surfactant concentration. The droplet sizes of emulsions stabilised by mixed emulsifier systems containing low concentrations of O/W surfactants (Tween 60 or Sodium Caseinate) were smaller than those solely stabilised by either the surfactant or particles alone. At intermediate O/W surfactants concentrations, the droplet sizes of the emulsions increased. Further increases in the O/W surfactants' concentration, resulted in the complete removal of particles from the interface with the system now behaving as a surfactant-only stabilised emulsion. The behaviour of emulsions stabilised by emulsifier mixtures containing W/O surfactants was not dependent on the concentration of surfactant: no removal of particles was observed. Copyright © 2010 Elsevier Inc. All rights reserved.

  7. Influence of water concentrations on the phase transformation of a model surfactant/co-surfactant/water system

    Science.gov (United States)

    Lunkad, Raju; Srivastava, Arpita; Debnath, Ananya

    2017-02-01

    The influence of water concentrations on phase transformations of a surfactant/co-surfactant/water system is investigated by using all atom molecular dynamics simulations. At higher water concentrations, where surfactant (behenyl trimethyl ammonium chloride, BTMAC) to co-surfactant (stearyl alcohol, SA) ratio is fixed, BTMAC and SA self-assemble into spherical micelles, which transform into strongly interdigitated one dimensional rippled lamellar phases upon decreasing water concentrations. Fragmentation or fusions of spherical micelles of different sizes are evident from the radial distribution functions at different temperatures. However, at lower water concentrations rippled lamellar phase transforms into an LβI phase upon heating. Our simulations reveal that the concentrations of water can influence available space around the head groups which couple with critical thickness to accommodate the packing fraction required for respective phases. This directs towards obtaining a controlling factor to design desired phases important for industrial and medical applications in the future.

  8. Effects of pH and buffer concentration on the thermal stability of etanercept using DSC and DLS.

    Science.gov (United States)

    Kim, Nam Ah; An, In Bok; Lim, Dae Gon; Lim, Jun Yeul; Lee, Sang Yeol; Shim, Woo Sun; Kang, Nae-Gyu; Jeong, Seong Hoon

    2014-01-01

    The protein size, electrical interaction, and conformational stability of etanercept (marketed as Enbrel®) were examined by thermodynamic and light scattering methods with changing pH and buffer concentration. As pH of etanercept increased from pH 6.6 to 8.6, electrical repulsion in the solution increased, inducing a decrease in protein size. However, the size changed less in high buffer concentration and irreversible aggregation issues were not observed; in contrast, aggregates of about 1000 nm were observed in low buffer concentration at the pH range. Three significant unfolding transitions (Tm) were observed by differential scanning calorimetry (DSC). Unlikely to Tm1, Tm2 and Tm3 were increased as the pH increased. Higher Tm at high buffer concentration was observed, indicating increased conformational stability. The apparent activation energy of unfolding was further investigated since continuous increase of Tm2 and Tm3 was not sufficient to determine optimal conditions. A higher energy barrier was calculated at Tm2 than at Tm3. In addition, the energy barriers were the highest at pH from 7.4 to 7.8 where higher Tm1 was also observed. Therefore, the conformational stability of protein solution significantly changed with pH dependent steric repulsion of neighboring protein molecules. An optimized pH range was obtained that satisfied the stability of all three domains. Electrostatic circumstances and structural interactions resulted in irreversible aggregation at low buffer concentrations and were suppressed by increasing the concentration. Therefore, increased buffer concentration is recommended during protein formulation development, even in the earlier stages of investigation, to avoid protein instability issues.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jin Danyue; Jiang Xia [State Environmental Protect Key Laboratory of Lake Eutrophication Control, Research Center of Lake Environment, Chinese Research Academy of Environmental Science, No. 8 Dayangfang, An Wai Bei Yuan, Beijing 100012 (China)]. E-mail: jiangxia@craes.org.cn; Jing Xin [State Environmental Protect Agency of China (China); Ou Ziqing [Institute of Applied Ecology, Chinese Academy of Science, Shenyang 110016 (China)

    2007-06-01

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

  10. An Unusual Variation of Surface Tension with Concentration of.Mixed Cationic-anionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    肖进新; 暴艳霞

    2001-01-01

    There are two platforms in the surface tension vs. concentration curve (γ-lgC curve) of cationic-anionic surfactant mixtures. The first platform is the same as that of common surfactant solution, and the cross point is the CMC. After the CMC, the mixtures form precipitate. At higher concentration, the mixtures form homogeneous sloution.When the mixtures form homogeneous solution at high concentration. surface tension increases with concentration, the becomes constant.So the γ-lgC curve exhibits the second platform. The surface tension at the second platform increases by increasing molar ratio of two surfactants and polar group size of surfactants, and decreases with adding inorganic salts.

  11. Surfactant softening of plant leaf cuticle model wax--a Differential Scanning Calorimetry (DSC) and Quartz Crystal Microbalance with Dissipation (QCM-D) study.

    Science.gov (United States)

    Fagerström, Anton; Kocherbitov, Vitaly; Westbye, Peter; Bergström, Karin; Arnebrant, Thomas; Engblom, Johan

    2014-07-15

    The aim was to quantify the softening effect that two surfactants (C10EO7 and C8G1.6) have on a plant leaf cuticle model wax. Effects on the thermotropic phase behavior and fluidity of the wax (C22H45OH/C32H66/H2O) were determined. The model wax is crystalline at ambient conditions, yet it is clearly softened by the surfactants. Both surfactants decreased the transition temperatures in the wax and the G″/G' ratio of the wax film increased in irreversible steps following surfactant exposure. C10EO7 has a stronger fluidizing effect than C8G1.6 due to stronger interaction with the hydrophobic waxes. Intracuticular waxes (IW) comprise both crystalline and amorphous domains and it has previously been proposed that the fluidizing effects of surfactants are due to interactions with the amorphous parts. New data suggests that this may be a simplification. Surfactants may also absorb in crevices between crystalline domains. This causes an irreversible effect and a softer cuticle wax.

  12. A DSC investigation on the influence of gemini surfactant stereochemistry on the organization of lipoplexes and on their interaction with model membranes.

    Science.gov (United States)

    Aleandri, S; Bonicelli, M G; Giansanti, L; Giuliani, C; Ierino, M; Mancini, G; Martino, A; Scipioni, A

    2012-12-01

    Previous investigations showed that the extent of DNA condensation and the efficiency in the transfection of liposomes formulated with 1,2-dimyristoyl-sn-glycero-phosphocholine and cationic stereomeric gemini surfactants depend heavily on the stereochemistry of the gemini. The influence of the stereochemistry on the interaction of lipoplexes with zwitterionic and anionic cell membrane models was investigated by differential scanning calorimetry to rationalize their different biological behavior. Further, the thermotropic behavior of the corresponding liposomes and of the spontaneous self-assemblies of gemini surfactants in the presence and in the absence of DNA was evaluated to correlate the physicochemical properties of lipoplexes and the stereochemistry of the cationic component. The obtained results show that the stereochemistry of the gemini surfactant controls lipoplexes organization and their mode and kinetic of interaction with different cell membrane models.

  13. The binding and insertion of imidazolium-based ionic surfactants into lipid bilayers: the effects of the surfactant size and salt concentration.

    Science.gov (United States)

    Lee, Hwankyu; Jeon, Tae-Joon

    2015-02-28

    Imidazolium-based ionic surfactants with hydrocarbon tails of different sizes were simulated with lipid bilayers at different salt concentrations. Starting with the random position of ionic surfactants outside the bilayer, surfactants with long tails mostly insert into the bilayer, while those with short tails show the insertion of fewer surfactant molecules, indicating the effect of the tail length. In particular, surfactants with a tail of two or four hydrocarbons insert and reversibly detach from the bilayer, while the inserted longer surfactants cannot be reversibly detached because of the strong hydrophobic interaction with lipid tails, in quantitative agreement with experiments. Longer surfactants insert more deeply and irreversibly into the bilayer and thus increase lateral diffusivities of the bilayer, indicating that longer surfactants more significantly disorder lipid bilayers, which also agrees with experiments regarding the effect of the tail length of ionic surfactants on membrane permeability and toxicity. Addition of NaCl ions weakens the electrostatic interactions between headgroups of surfactants and lipids, leading to the binding of fewer surfactants into the bilayer. In particular, our simulation findings indicate that insertion of ionic surfactants can be initiated by either the hydrophobic interaction between tails of surfactants and lipids or the electrostatic binding between imidazolium heads and lipid heads, and the strength of hydrophobic and electrostatic interactions depends on the tail length of surfactants.

  14. 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.

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

    Science.gov (United States)

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

    2017-03-01

    The present study was designed to provide information regarding the effect of the molecular structure of amphoteric amine-oxide-based surfactants and the initial surfactant concentration on their ultimate biodegradation. Moreover, given this parameter's pH-dependence, the effect of pH was also investigated. Three amine-oxide-based surfactants with structural differences in their hydrophobic alkyl chain were tested: Lauramine oxide (AO-R12), Myristamine oxide (AO-R14) and Cocamidopropylamine oxide (AO-Cocoamido). We studied the ultimate biodegradation using the Modified OECD Screening Test at initial surfactant concentrations ranged from 5 to 75 mg L(-1) and at pH levels from 5 to 7.4. The results demonstrate that at pH 7.4, amine-oxide-based surfactants are readily biodegradable. In this study, we concluded that ω-oxidation can be assumed to be the main biodegradation pathway of amine-oxides and that differences in the biodegradability between them can be explained by the presence of an amide group in the alkyl chain of AO-Cocoamido; the CN fission of the amide group slows down their mineralization process. In addition, the increase in the concentration of the surfactant from 5 to 75 mg L(-1) resulted in an increase in the final biodegradation of AO-R12 and AO-R14. However, in the case of AO-Cocoamido, a clear relationship between the concentration and biodegradation cannot be stated. Conversely, the biodegradability of AO-R12 and AO-R14 was considerably lower in an acid condition than at a pH of 7.4, whereas AO-Cocoamido reached similar percentages in acid conditions and at a neutral pH. However, microorganisms required more time to acclimate.

  16. Dependence of the solubility of atmospheric oxygen in weakly alkaline aqueous solutions on surfactant concentration

    Science.gov (United States)

    Chistyakova, G. V.; Koksharov, S. A.; Vladimirova, T. V.

    2012-11-01

    The solubility of atmospheric oxygen in solutions of surfactants of different natures at 293 K and pH 8 is determined by gas chromatography. It is found that additives of nonionic surfactants decrease the oxygen content in the solution in the premicellar region and increase its solubility in the micellar region. It is shown that, for anionic surfactants, a decrease in the solubility of O2 is observed over the entire concentration range.

  17. Effect of low concentrations of synthetic surfactants on polycyclic aromatic hydrocarbons (PAH) biodegradation

    OpenAIRE

    A. C. Rodrigues; Nogueira, R; Melo, L. F.; A. G. Brito

    2013-01-01

    The present study is focused on the effect of synthetic surfactants, at low concentration, on the kinetics of polycyclic aromatic hydrocarbons (PAH) biodegradation by Pseudomonas putida ATCC 17514 and addresses the specific issue of the effect of the surfactant on bacterial adhesion to PAH, which is believed to be an important mechanism for the uptake of hydrophobic compounds. For that purpose, three surfactants were tested, namely, the nonionic Tween 20, the anionic sodium dodecyl sulphate (...

  18. (NLC-Effect of Surfactant Concentration on the Formulation Properties

    Directory of Open Access Journals (Sweden)

    Akram Pezeshki

    2014-12-01

    Conclusion: This study suggests that surfactant significantly influences the final product properties. Our findings may pave the way of researchers to focus on fortifying the beverages with various lipophilic nutraceuticals.

  19. The Effect of Surfactant on Synthesis of ZSM-5 in a Super-Concentrated System

    Institute of Scientific and Technical Information of China (English)

    Li Haiyan; Qin Lihong; Gao Guangbo; Sun Famin

    2016-01-01

    ZSM-5 zeolite was synthesized in a super-concentrated system using different kinds of surfactants. The ZSM-5 samples were characterized by XRD, SEM, FT-IR and BET techniques. The surfactant could change the properties of ZSM-5 zeolite, including the crystallinity, the crystal grain size, the surface area, the pore volume and the Si/Al mole ratio.

  20. 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)

  1. Thermodynamically consistent description of the hydrodynamics of free surfaces covered by insoluble surfactants of high concentration

    OpenAIRE

    Thiele, Uwe; Archer, Andrew J.; Plapp, Mathis

    2012-01-01

    In this paper we propose several models that describe the dynamics of liquid films which are covered by a high concentration layer of insoluble surfactant. First, we briefly review the 'classical' hydrodynamic form of the coupled evolution equations for the film height and surfactant concentration that are well established for small concentrations. Then we re-formulate the basic model as a gradient dynamics based on an underlying free energy functional that accounts for wettability and capill...

  2. Effect of concentration on surfactant micelle shapes--A molecular dynamics study

    Institute of Scientific and Technical Information of China (English)

    GAO Jian; GE Wei; LI Jinghai

    2005-01-01

    Many aspects of the behavior of surfactants have not been well understood due to the coupling of many different mechanisms. Computer simulation is, therefore, attractive in the sense that it can explore the effect of different mechanisms separately. In this paper, the shapes, structures and sizes of sodium dodecylbenzenesulfonate (SDBS) micelles under different concentrations in an oil/water mixture were studied via molecular dynamics (MD) simulations using a simplified atomistic model which basically maintains the hydrophile and lipophile properties of the surfactant molecules. Above the critical micellar concentration (cmc), surfactant molecules aggregate spontaneously to form a wide variety of assemblies, from spherical to rodlike, wormlike and bilayer micelles. Changes in their ratios of the principle moments of inertia (g1/g3, g2/g3) indicated the transition of micelle shapes at different concentrations. The aggregation number of micelle is found to have a power-law dependence on surfactant concentration.

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

    Science.gov (United States)

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

  4. Surfactants and Sterols Concentrations in the Surface Microlayer of the Estuarine Areas of Selangor River, Malaysia

    Science.gov (United States)

    Latif, M. T.; Alsalahi, M. A.; Ali, M. M.; Dominick, D.; Khan, M. F.; Wahid, N. B. A.; Mustaffa, N. I. H.

    2016-02-01

    This study aims to determine the concentration of surfactant and sterols as biomarkers in the surface microlayer (SML) in estuarine areas of the Selangor River, Malaysia. SML samples were collected during different seasons using a rotation drum method. The compositions of surfactants were determined as methylene blue active substances (MBAS) and disulphine blue active substances (DBAS) as anionic and cationic surfactants respectively. The concentration of sterols was determined using a gas chromatography equipped with a flame ionization detector (GC-FID). The results show that the concentrations of surfactants around the estuarine area were dominated by anionic surfactants (MBAS) with average concentrations of 0.39 µmol L-1. .The concentrations of total sterols in the SML ranged from 107.06 to 505.55 ng L-1. The surfactants and total sterol concentrations were found to be higher in the wet season compare to dry season. Cholesterol was found to be the most abundant sterols component in the SML of the Selangor River. The diagnostic ratios of sterols show the influence of natural sources and waste on the contribution of sterols in the SML. Further analysis, using principal component analysis (PCA), showed distinct inputs of sterols derived from human activity (40.58%), terrigenous and plant inputs (22.59%) as well as phytoplankton and marine inputs (17.35%).

  5. Thermodynamically consistent description of the hydrodynamics of free surfaces covered by insoluble surfactants of high concentration

    CERN Document Server

    Thiele, Uwe; Plapp, Mathis

    2012-01-01

    In this paper we propose several models that describe the dynamics of liquid films which are covered by a high concentration layer of insoluble surfactant. First, we briefly review the 'classical' hydrodynamic form of the coupled evolution equations for the film height and surfactant concentration that are well established for small concentrations. Then we re-formulate the basic model as a gradient dynamics based on an underlying free energy functional that accounts for wettability and capillarity. Based on this re-formulation in the framework of nonequilibrium thermodynamics, we propose extensions of the basic hydrodynamic model that account for (i) nonlinear equations of state, (ii) surfactant-dependent wettability, (iii) surfactant phase transitions, and (iv) substrate-mediated condensation. In passing, we discuss important differences to most of the models found in the literature.

  6. Separating excess surfactant from silver and gold nanoparticles in micellar concentrates by means of nonaqueous electrophoresis

    Science.gov (United States)

    Bulavchenko, A. I.; Demidova, M. G.; Popovetskiy, P. S.; Podlipskaya, T. Yu.; Plyusnin, P. E.

    2017-08-01

    It is shown by physicochemical means (IR Fourier spectroscopy, CHN-analysis with preliminary sorption of surfactant on SiO2) that the content of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in an electrophoretic concentrate remains unchanged during the electrophoretic concentration of silver and gold nanoparticles. Diluting the concentrate and carrying out the second stage of electrophoresis reduces the concentration of surfactant from 0.25 to 0.015 M while maintaining the mass concentration of nanoparticles. Nanoparticles in organosols before and after electrophoresis are characterized by means of photon correlation spectroscopy, phase analysis light scattering, and spectrophotometry. Conducting films on glass substrates are obtained from concentrates with a different contents of surfactant via water-alcohol treatment and thermolysis.

  7. Research on the Influence of the Type of Surfactant and Concentrator in Aqueous Dispersion of Pigments.

    Science.gov (United States)

    Makarewicz, Edwin; Michalik, Agnieszka

    2014-01-01

    This work reports tests performed to evaluate the stability of aqueous dispersions of inorganic oxide pigments with different specific surface areas, with the use of anionic and non-ionic surfactants and concentrators. Color mixtures of oxide compounds of blue, green, olive and brown with the unit cell spinel structure were used as pigments. The sodium salt of sulfosuccinic acid monoester, oxyethylenated nonylphenol and ethoxylated derivatives of lauryl alcohol, fatty alcohol and fatty amine were used as surfactants. The concentrators used were: poly(vinyl alcohol), the sodium salt of carboxymethyl cellulose as well as a water-based polyurethane oligomer. The highest dispersion efficiency was found for dispersed systems in which surfactant and concentrator were incorporated in the formula. The one containing the sodium salt of carboxymethyl cellulose or polyurethane oligomer with ethoxylated saturated fatty alcohol or fatty amine was found to be the most efficient. It was discovered that a higher dispersion efficiency corresponds to pigments with larger specific surface. The efficiency is also found to improve when the concentrator is an acrylic polymer or copolymer made up of two acrylic species. In this case, the concentrator interaction with the surfactant is more effective if the value of its boundary viscosity number is higher. This observation confirms the existence of interactions between macro-chains of the concentrator and surfactant molecules forming micelles with the pigment particles.

  8. Competitive solubilization of phenol by cationic surfactant micelles in the range of low additive and surfactant concentrations.

    Science.gov (United States)

    Chaghi, Radhouane; de Ménorval, Louis-Charles; Charnay, Clarence; Derrien, Gaëlle; Zajac, Jerzy

    2009-05-01

    Competitive interactions of phenol (PhOH) with micellar aggregates of hexadecyltrimethylammonium bromide (HTAB) against 1-butanol (BuOH) in aqueous solutions at surfactant concentrations close to the critical micelle concentration (CMC), BuOH concentration of 0.5 mmol kg(-1), and phenol contents of 1, 5, or 10 mmol kg(-1) have been investigated at 303 K by means of (1)H NMR spectroscopy, titration calorimetry, and solution conductimetry. The solubilization loci for phenol were deduced from the composition-dependence of the (1)H chemical shifts assigned to various protons in the surfactant and additive units. Since in pure HTAB solutions phenol is already in competition with Br(-), addition of 1 mmol kg(-1) NaBr to the system weakens the phenol competitiveness. The presence of butanol in the HTAB micelles causes phenol to penetrate deeper toward the hydrophobic micelle core. For higher phenol contents, the butanol molecules are constrained to remain in the bulk solution and are progressively replaced within the HTAB micelles by the aromatic units. The competitive character of phenol solubilization against butanol is well supported by changes in the thermodynamic parameters of HTAB micellization in the presence of both of the additives.

  9. Microwave corneosurfametry and the short-duration dansyl chloride extraction test for rating concentrated irritant surfactants.

    Science.gov (United States)

    Goffin, V; Piérard, G E

    2001-01-01

    There are ethical concerns to conduct in vivo tests in the animal and human to provide evidence that cosmetics and other topical products are safe. To compare two methods, namely the short-duration dansyl chloride extraction test and the microwave corneosurfametry bioassay, to test the irritation potential of concentrated surfactant systems. Five surfactants and water were tested using the in vivo test and the bioassay. A significant linear correlation was found between data yielded by the two procedures. The short-duration dansyl chloride extraction test and the microwave corneosurfametry bioassay provide similar information. The latter has the advantage of being safe.

  10. The effect of surfactant and solid phase concentration on drug aggregates in model aerosol propellent suspensions.

    Science.gov (United States)

    Bower, C; Washington, C; Purewal, T S

    1996-04-01

    The effect of increasing solid phase concentration on the morphology and flocculation rate of model aerosol suspensions has been investigated. Suspensions of micronized salbutamol sulphate and lactose in trichlorotrifluoroethane (P113) were studied under conditions of increasing shear stress. By use of image analysis techniques, measurement of aggregate size, fractal dimension and rate of aggregation was performed. The effect of the surfactant sorbitan monooleate on morphology and flocculation rate was also studied. Increased solid phase concentration caused an increase in the rate of aggregation and average aggregate size at a given value of shear stress. Surfactant addition retarded the aggregation rate, and caused a shift from a diffusion-limited cluster aggregation to a reaction-limited cluster aggregation mechanism. The aggregate profiles showed a corresponding change from rugged and crenellated without surfactant, to increasingly smooth and Euclidian with increasing surfactant concentration. The morphological changes were characterized by a decrease in the average boundary fractal dimension which also correlated well with the corresponding reduction in aggregation rate.

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

    Science.gov (United States)

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

    2015-07-15

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

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

    Science.gov (United States)

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

    2009-08-04

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

  13. Effect of Surfactant Concentration in the Emulsions on the Process of Oleophilic Porous Structures Imbibition

    Directory of Open Access Journals (Sweden)

    Shtyka Olga S.

    2016-01-01

    Full Text Available The spontaneous imbibition has been a subject of the scientific interest being a background process for numerous industrial technologies and occurring in the natural environment. In literature the experimental and theoretical results regarding this phenomenon describe a media imbibition with single-phase liquids and the relation between the process rate and media characteristics. The imbibition of oleophilic porous structures with two-phase liquids, only one phase of which was wetting, is an objective of the current publication. The main purpose is to estimate the influence of both surfactant fraction and the dispersed phase concentration on the mentioned process. The imbibition rate was investigated during model experiments with stabilized oil-in-water emulsions having the dispersed phase concentrations of 10 vol%, 30 vol% and 50 vol%. The prepared emulsions differed with fraction of the added surfactant, i.e. 1 vol%, 2 vol% and 5 vol%. The obtained results allowed to conclude that at the him≥0.02 m, the dispersed phase concentration and viscosity decreased versus height. However, the raise of the surfactant fraction caused the increase of mass and height of the imbibed emulsions in porous medium. Moreover, this provided increasing of viscosity and a change of emulsions behaviour as a liquid.

  14. Formation at low surfactant concentrations and characterization of mesoporous MCM-41

    Institute of Scientific and Technical Information of China (English)

    陈晓银; 丁国忠; 陈海鹰; 李全芝

    1997-01-01

    At low concentrations of cetyltrimethylammonium bromide,all silica-based mesoporous materials with hexagonal phase have been synthesized via interactions between self-assembled surfactant molecule aggregates and aniomc silicate polymers.The resulting materials are characterized by XRD,FT-IR,solid state 29Si MAS NMR,thermal analysis and N2 adsorption-desorption measurements.After soluble ions are removed,the interactors between surfactant micelles and silicate polymers are reorganized and then form mesostructures 1 he hexagonal framework is sonsistent with amorphous silica gel.The structures of materials depend on the synthesis conditions Hydrothermal process improves the interactions between molecules and increases the degree of framework silicon atom polymerization The.surface area and the mesopore volume of the material prepared at 100℃ increase by 87% and 71 %,respectively,compared with those obtained at room temperature.

  15. Concentrations of surfactants and sterols in the surface microlayer of the estuarine areas of Selangor River, Malaysia

    Science.gov (United States)

    Alsalahi, Murad Ali; Talib Latif, Mohd; Mohd Ali, Masni; Dominick, Doreena; Firoz Khan, Md; Bahiyah Abd Wahid, Nurul; Ili Hamizah Mustaffa, Nur

    2016-04-01

    This study determined the concentration of surfactant and sterols as biomarkers in the surface microlayer (SML) in estuarine areas of the Selangor River, Malaysia. SML samples were collected during different seasons using a rotation drum method. The compositions of surfactants in SML were determined as methylene blue active substances (MBAS) and disulphine blue active substances (DBAS) as anionic and cationic surfactants respectively. The concentration of sterols was determined using a gas chromatography equipped with a flame ionisation detector (GC-FID). The results show that the concentrations of surfactants around the estuarine area were dominated by anionic surfactants (MBAS) with average concentrations of 0.39 μmol L-1. The concentrations of total sterols in the SML ranged from 107.06 to 505.55 ng L-1. The surfactants and total sterol concentrations were found to be higher in the wet season. Cholesterol was found to be the most abundant sterols component in the SML of the Selangor River. The diagnostic ratios of sterols show the influence of natural sources and waste on the contribution of sterols in the SML. Further analysis, using principal component analysis (PCA), showed distinct inputs of sterols derived from human activity (40.58%), terrigenous and plant inputs (22.59%) as well as phytoplankton and marine inputs (17.35%).

  16. Critical micelle concentration of surfactants in aqueous buffered and unbuffered systems

    Energy Technology Data Exchange (ETDEWEB)

    Fuguet, Elisabet [Departament de Quimica Analitica, Universitat de Barcelona, Facultat de Quimica, Marti i Franques 1-11, 08028 Barcelona (Spain); Rafols, Clara [Departament de Quimica Analitica, Universitat de Barcelona, Facultat de Quimica, Marti i Franques 1-11, 08028 Barcelona (Spain); Roses, Marti [Departament de Quimica Analitica, Universitat de Barcelona, Facultat de Quimica, Marti i Franques 1-11, 08028 Barcelona (Spain); Bosch, Elisabeth [Departament de Quimica Analitica, Universitat de Barcelona, Facultat de Quimica, Marti i Franques 1-11, 08028 Barcelona (Spain)]. E-mail: e.bosch@ub.edu

    2005-08-29

    Critical micelle concentration (CMC) of sodium dodecyl sulphate (SDS), lithium perfluorooctanesulfonate (LPFOS), hexadecyltrimethylammonium bromide (HTAB), tetradecyltrimethylammonium bromide (TTAB), and sodium cholate (SC), surfactants commonly used as pseudostationary phases in micellar electrokinetic chromatography (MEKC), have been determined by means of three different methods: MEKC, spectrophotometry, and conductometry. Determinations have been performed in water, and also in different concentrations of phosphate buffer at pH 7.0. CMC values ranging from 8.08 (water) to 1.99 (50 mM phosphate buffer) mM for SDS, from 7.16 (water) to 2,81 (30 mM phosphate buffer) mM for LPFOS, from 3.77 (water) to 1.93 (20 mM phosphate buffer) mM for TTAB, from 0.91 (water) to {approx}0.34 (20 mM phosphate buffer) for HTAB, and around 13 mM (20 mM phosphate buffer) for SC, are obtained. The effect of the electrolyte concentration on the CMC, as well as the linear relationship between the electrolyte counter-ion concentration and the CMC are discussed. This linear relationship provides an easy way for users to estimate the CMC of a MEKC system, at a given electrolyte concentration. A comparison between experimental methods, as well as a discussion about the suitability of a given method for the determination of the CMC for a given surfactant system is also provided.

  17. Rape phosphatide concentrate in the technologies of surfactants production by the Actinobacteria

    Directory of Open Access Journals (Sweden)

    N. Koretska

    2015-05-01

    Full Text Available Introduction. Due to the fact that the production of microbial surfactants is limited by the low yield of end products and high cost of processes, the actual task is to optimize and reduce the cost of the technology of biosurfactants synthesis. One of the solutions of this problem is to use the industrial wastes, including rape phosphatide concentrate (PC. Materials and methods. Hexadecane and rape phosphatide concentrate (2% were used as a carbon source in a nutrient medium for the cultivation of bacteria. Lipids were extracted from a cell mass and supernatant by the mixture of chloroform-methanol 2:1. The qualitative analysis of metabolites was performed by a thin layer chromatography. Results and discussion. The peculiarities of synthesis of biosurfactants by strains G. rubripertincta UCM Aс-122 and R. erythropolis Au-1 during the growth on the nutrient media with rape phosphatide concentrate as a carbon source was studied. Quantity of biomass was 9.4 – 10.1 g/l, exopoly mers –8.9-9.5 g/l and the content of cellbound trehalose lipids was 1.37 – 2.26 g/l; whereas the content of exogenous trehalose lipids –metabolites of R. erythropolis Au-1 was 2.95 g/l. It was found that the addition of trehalose lipids (0.01 g/l to the nutrient medium caused the increase of biomass on 14.6 –17.0 % and cell-bound lipids on 13.9 –15.5 %. Conclusions. Rape phosphatide concentrate is economically viable carbon source in the technologies of surfactant production by Actinobacteria. Its use promotes an increasing of exogenous surfactants strain R. erythropolisAu-1 in 3-fold compared with cultivation on nutrient medium with hexadecane. Trehalose lipids show a stimulating effect on growth and synthesis of biosurfactants by strains of G. rubripertincta UCM Ac-122 and R. erythropolisAu-1.

  18. Avaliação por SAXS e DSC das interações entre H2O e Renex-100

    Directory of Open Access Journals (Sweden)

    Daniella Dias Palombino de Campos

    2012-01-01

    Full Text Available The aggregation behavior of the non-ionic surfactant Renex-100 in aqueous solutions and mesophases was evaluated by SAXS in a wide range of concentrations, between 20 and 30 °C. Complementary, water interactions were defined by DSC curves around 0°C. SAXS showed that the system undergoes the following phase transitions, from diluted to concentrated aqueous solutions: 1 isotropic solution of Renex aggregates; 2 hexagonal mesophase; 3 lamellar mesophase; and 4 isotropic solution. DSC analysis indicated the presence of interfacial water above 70wt%, which agreed with the segregation of free water to form the structural mesophases observed by SAXS bellow this concentration.

  19. Oil Analysis by Fast DSC

    NARCIS (Netherlands)

    Wetten, I.A.; Herwaarden, A.W.; Splinter, R.; Ruth, van S.M.

    2014-01-01

    Thermal analysis of Olive and Sunflower Oil is done by Fast DSC to evaluate its potential to replace DSC for adulteration detection. DSC measurements take hours, Fast DSC minutes. Peak temperatures of the crystallisation peak in cooling for different Olive and Sunflower Oils are both comparable to D

  20. Oil Analysis by Fast DSC

    NARCIS (Netherlands)

    Wetten, I.A.; Herwaarden, A.W.; Splinter, R.; Ruth, van S.M.

    2014-01-01

    Thermal analysis of Olive and Sunflower Oil is done by Fast DSC to evaluate its potential to replace DSC for adulteration detection. DSC measurements take hours, Fast DSC minutes. Peak temperatures of the crystallisation peak in cooling for different Olive and Sunflower Oils are both comparable to

  1. Modeling of the Critical Micelle Concentration (CMC) of Nonionic Surfactants with an Extended Group-Contribution Method

    DEFF Research Database (Denmark)

    Mattei, Michele; Kontogeorgis, Georgios; Gani, Rafiqul

    2013-01-01

    A group-contribution (GC) property prediction model for estimating the critical micelle concentration (CMC) of nonionic surfactants in water at 25 °C is presented. The model is based on the Marrero and Gani GC method. A systematic analysis of the model performance against experimental data......; and carbohydrate derivate ethers, esters, and thiols. The model developed consists of linear group contributions, and the critical micelle concentration is estimated using the molecular structure of the nonionic surfactant alone. Compared to other models used for the prediction of the critical micelle...... is carried out using data for a wide range of nonionic surfactants covering a wide range of molecular structures. As a result of this procedure, new third order groups based on the characteristic structures of nonionic surfactants are defined and are included in the Marrero and Gani GC model. In this way...

  2. Physical stability of N,N-dimethyldecanamide/α-pinene-in-water emulsions as influenced by surfactant concentration.

    Science.gov (United States)

    Trujillo-Cayado, L A; Alfaro, M C; García, M C; Muñoz, J

    2017-01-01

    In recent years, interest in submicron emulsions has increased due to their high stability and potential applications in the encapsulation and release of active ingredients in many industrial fields, such as the food industry, pharmaceuticals or agrochemicals. Furthermore, the social demand for eco-friendly solutions to replace hazardous solvents in many dispersion formulations has steadily risen. In this study, the influence of surfactant concentration on the formation and physical stability of submicron oil-in-water emulsions using a high-pressure dual-channel homogenizer (microfluidizer) has been investigated. The formulation involved the use of a blend of two green solvents (N,N-dimethyldecanamide and α-pinene) as dispersed phase and a nonionic polyoxyethylene glycerol ester derived from coconut oil as emulsifier (Levenol(®) C-201), which enjoys a European eco-label. Therefore, these emulsions may find applications as matrices for agrochemicals. Physical stability and rheological properties of the emulsions studied showed an important dependence on the eco-friendly surfactant concentration. The lowest surfactant concentration (1wt%) yielded the onset of a creaming process after a short aging time and was not enough to avoid recoalescence during emulsification. On the other hand, the higher surfactant concentrations (4-5wt%) resulted in depletion flocculation, which in turn triggered emulsion destabilization by coalescence. The optimum physical stability was exhibited by emulsions containing intermediate surfactant concentrations (2-3wt%) since coalescence was hardly significant and the onset of a weak creaming destabilization process was substantially delayed.

  3. Determination of the Critical Micelle Concentration of Cationic Surfactants: An Undergraduate Experiment

    Science.gov (United States)

    Huang, Xirong; Yang, Jinghe; Zhang, Wenjuan; Zhang, Zhenyu; An, Zesheng

    1999-01-01

    A novel method based on the catalytic effect of micelles exerted by cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB), respectively, on the indicator reaction between H2O2 and bromopyrogallol red (BPR), a triphenylmethane dye, was developed for undergraduates to determine the critical micelle concentration (cmc) of CTAB and CPB. The indicator reaction was monitored by a fixed-time kinetic-spectrophotometric technique. Under the experimental conditions the cmc values of CTAB and CPB were (4.8 ± 0.3) x 10-4 mol/L and (4.5 ± 0.3) x 10-4mol/L, which were close to the literature values of 9.2 x 10-4 mol/L and 9.0 x 10-4 mol/L, respectively. Detailed discussion on the selection of experimental conditions was made to minimize the effect of electrolytes on the cmc's of surfactants and to maintain the high accuracy of the experimental data. As an undergraduate physicochemical laboratory experiment the present method had several attractive features. The procedure is simple and easy to perform, does not require special equipment, and does not need expensive or toxic reagents. In addition, it is a versatile method that can be applied to a wide variety of both anionic and cationic surfactants.

  4. Prediction on Critical Micelle Concentration of Nonionic Surfactants in Aqueous Solution: Quantitative Structure-Property Relationship Approach

    Institute of Scientific and Technical Information of China (English)

    王正武; 黄东阳; 宫素萍; 李干佐

    2003-01-01

    In order to predict the critical micelle concentration (cmc) of nonionic surfactants in aqueous solution, a quantitative structure-property relationship (QSPR) was found for 77 nonionic surfactants belonging to eight series. The best-regressed model contained four quantum-chemical descriptors, the heat of formation (△H), the molecular dipole moment (D), the energy of the lowest unoccupied molecular orbital (ELUMO) and the energy of the highest occupied molecular orbital (EHOMO) of the surfactant molecule; two constitutional descriptors, the molecular weight of surfactant (M) and the number of oxygen and nitrogen atoms (nON ) of the hydrophilic fragment of surfactant molecule; and one topological descriptor, the Kier & Hall index of zero order (KH0) of the hydrophobic fragment of the surfactant. The established general QSPR between Ig (cmc) and the descriptors produced a relevant coefficient of multiple determination: R2=0.986. When cross terms were considered, the corresponding best model contained five descriptors ELUMO, D,KH0, M and a cross term nON·KH0, Which also produced the same coefficient as the seven-parameter model.

  5. Effect of Temperature on the Critical Micelle Concentration and Micellization Thermodynamic of Nonionic Surfactants: Polyoxyethylene Sorbitan Fatty Acid Esters

    Directory of Open Access Journals (Sweden)

    Ehsan Mohajeri

    2012-01-01

    Full Text Available In this study, non-ionic surfactants, polyoxyethylene sorbitan fatty acid esters (polysorbate are chosen to examine the temperature effect on the CMC over a wide temperature range. The enthalpy and entropy of micelle formation are evaluated according to the phase separation model. The surface tension of solutions was determined by means of Du Nöuys ring. The CMC values were taken from the sharp breaks in the surface tension vs. logarithms of surfactant concentration plots. As the surfactants' chain length increases the CMC at a constant temperature decreases, which is directly related to the decrease of hydrophilicity of the molecules. For each surfactant, as the system temperature increases, the CMC initially decreases and then increases, owing to the smaller probability of hydrogen bond formation at higher temperatures. The onset of micellization tends to occur at higher concentrations as the temperature increases. To evaluate the enthalpy of micellization, the CMCs are first correlated by a polynomial equation. It is found that ∆Gºm decreases monotonically as the temperature increases over the whole temperature range. Both ∆Hºm and ∆Sºm appear to be decrease monotonically with an increase in temperature. The compensation temperature was found to be 42 ºC by linear regression over the whole temperature range and for all three surfactant systems together.

  6. Calix-arene silver nanoparticles interactions with surfactants are charge, size and critical micellar concentration dependent.

    Science.gov (United States)

    Tauran, Yannick; Brioude, Arnaud; Shahgaldian, Patrick; Cumbo, Alessandro; Kim, Beomjoon; Perret, Florent; Coleman, Anthony W; Montasser, Imed

    2012-10-04

    The interactions of silver nanoparticles capped by various calix[n]arenes bearing sulphonate groups at the para and/or phenolic faces with cationic, neutral and anionic surfactants have been studied. Changes in the plasmonic absorption show that only the calix[4]arene derivatives sulphonated at the para-position interact and then only with cationic surfactants. The interactions follow the CMC values of the surfactants either as simple molecules or mixed micelles.

  7. INDUCTION OF AGGREGATE FORMATION OF CATIONIC POLYSOAPS AND SURFACTANTS BY LOW CONCENTRATIONS OF ADDITIVES IN AQUEOUS-SOLUTION

    NARCIS (Netherlands)

    WANG, GJ; ENGBERTS, JBFN

    1994-01-01

    The induction of aggregate formation of cationic polysoaps ((CL)-Copol C1-12), cetyltrimethylammonium bromide (CTAB), n-dodecyltrimethylammonium bromide (DTAB), and n-dodecylmethyldiallylammonium bromide (DMDAAB) by low concentrations of Methyl Orange (10(-5)-10(-4) M) and anionic surfactants (conce

  8. Analyzing freely dissolved concentrations of cationic surfactant utilizing ion-exchange capability of polyacrylate coated solid-phase microextraction fibers

    NARCIS (Netherlands)

    Chen, Y.; Droge, S.T.J.; Hermens, J.L.M.

    2012-01-01

    A 7-μm polyacrylate (PA) coated fiber was successfully employed to determine freely dissolved concentrations of cationic surfactants by solid-phase microextraction (SPME) and utilizing the capability of the PA-coating to sorb organic cations via ion-exchange at carboxylic groups. Measured fiber-wate

  9. A novel, rapid and automated conductometric method to evaluate surfactant-cells interactions by means of critical micellar concentration analysis.

    Science.gov (United States)

    Tiecco, Matteo; Corte, Laura; Roscini, Luca; Colabella, Claudia; Germani, Raimondo; Cardinali, Gianluigi

    2014-07-25

    Conductometry is widely used to determine critical micellar concentration and micellar aggregates surface properties of amphiphiles. Current conductivity experiments of surfactant solutions are typically carried out by manual pipetting, yielding some tens reading points within a couple of hours. In order to study the properties of surfactant-cells interactions, each amphiphile must be tested in different conditions against several types of cells. This calls for complex experimental designs making the application of current methods seriously time consuming, especially because long experiments risk to determine alterations of cells, independently of the surfactant action. In this paper we present a novel, accurate and rapid automated procedure to obtain conductometric curves with several hundreds reading points within tens of minutes. The method was validated with surfactant solutions alone and in combination with Saccharomyces cerevisiae cells. An easy-to use R script, calculates conductometric parameters and their statistical significance with a graphic interface to visualize data and results. The validations showed that indeed the procedure works in the same manner with surfactant alone or in combination with cells, yielding around 1000 reading points within 20 min and with high accuracy, as determined by the regression analysis.

  10. Aggregation Kinetics and Transport of Single-Walled CarbonNanotubes at Low Surfactant Concentrations

    Science.gov (United States)

    Little is known about how low levels of surfactants can affect the colloidal stability of single-walled carbon nanotubes (SWNTs) and how surfactant-wrapping of SWNTs can impact ecological exposures in aqueous systems. In this study, SWNTs were suspended in water with sodium ...

  11. Fluorophotometric determination of critical micelle concentration (CMC) of ionic and non-ionic surfactants with carbon dots via Stokes shift.

    Science.gov (United States)

    Lavkush Bhaisare, Mukesh; Pandey, Sunil; Shahnawaz Khan, M; Talib, Abou; Wu, Hui-Fen

    2015-01-01

    A new and facile method for the determination of critical micelle concentration (CMC) of ionic and non-ionic surfactants is proposed in this article. Carbon dots exhibited substantial fluorescence and therefore enhanced the sensitivity of this evaluation. Understanding the formation of surfactant micelles is vital for the applications of biomedicine such as drug fabrication and smart molecular vehicles in delivering therapeutic dosage to various molecular sites. The fluorescence property of carbon dots was utilized for the first time to estimate the critical micelle concentration of surfactants. The central concept of the approach is based on the Stokes shift determination of a system composed of constant amount of carbon dots with varying concentrations of ionic and non-ionic surfactants. The synthesized carbon dots were characterized by FTIR, TEM, XRD, Raman, UV, and fluorescence spectroscope. The carbon dots were excited at 280 nm so as to obtain maximum emission for the Stokes shift measurement. The CMC value of cetyltrimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), Triton X-100, dodecyldimethyl(3-sulfopropyl)ammonium hydroxide (SB-12) evaluated by this approach was found to be 0.98, 7.3, 0.19, and 3.5mM, respectively. The signals of spectra were assigned and explained in terms of both electron transitions between specific molecular orbital and the interaction with solvent.

  12. Fibrinogen stability under surfactant interaction.

    Science.gov (United States)

    Hassan, Natalia; Barbosa, Leandro R S; Itri, Rosangela; Ruso, Juan M

    2011-10-01

    Differential scanning calorimetry (DSC), circular dichroism (CD), difference spectroscopy (UV-vis), Raman spectroscopy, and small-angle X-ray scattering (SAXS) measurements have been performed in the present work to provide a quantitatively comprehensive physicochemical description of the complexation between bovine fibrinogen and the sodium perfluorooctanoate, sodium octanoate, and sodium dodecanoate in glycine buffer (pH 8.5). It has been found that sodium octanoate and dodecanoate act as fibrinogen destabilizer. Meanwhile, sodium perfluorooctanoate acts as a structure stabilizer at low molar concentration and as a destabilizer at high molar concentration. Fibrinogen's secondary structure is affected by all three studied surfactants (decrease in α-helix and an increase in β-sheet content) to a different extent. DSC and UV-vis revealed the existence of intermediate states in the thermal unfolding process of fibrinogen. In addition, SAXS data analysis showed that pure fibrinogen adopts a paired-dimer structure in solution. Such a structure is unaltered by sodium octanoate and perfluoroctanoate. However, interaction of sodium dodecanoate with the fibrinogen affects the protein conformation leading to a complex formation. Taken together, all results evidence that both surfactant hydrophobicity and tail length mediate the fibrinogen stability upon interaction. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Evaluation of anionic surfactant concentrations in US effluents and probabilistic determination of their combined ecological risk in mixing zones.

    Science.gov (United States)

    McDonough, Kathleen; Casteel, Kenneth; Itrich, Nina; Menzies, Jennifer; Belanger, Scott; Wehmeyer, Kenneth; Federle, Thomas

    2016-12-01

    Alcohol sulfates (AS), alcohol ethoxysulfates (AES), linear alkyl benzenesulfonates (LAS) and methyl ester sulfonates (MES) are anionic surfactants that are widely used in household detergents and consumer products resulting in over 1 million tons being disposed of down the drain annually in the US. A monitoring campaign was conducted which collected grab effluent samples from 44 wastewater treatment plants (WWTPs) across the US to generate statistical distributions of effluent concentrations for anionic surfactants. The mean concentrations for AS, AES, LAS and MES were 5.03±4.5, 1.95±0.7, 15.3±19, and 0.35±0.13μg/L respectively. Since each of these surfactants consist of multiple homologues that differ in their toxicity, the concentration of each homologue measured in an effluent sample was converted into a toxic unit (TU) by normalizing to the predicted no effect concentration (PNEC) derived from high tier effects data (mesocosm studies). The statistical distributions of the combined TUs in the effluents were used in combination with distributions of dilution factors for WWTP mixing zones to conduct a US-wide probabilistic risk assessment for the aquatic environment for each of the surfactants. The 90th percentile level of TUs for AS, AES, LAS and MES in mixing zones were 1.89×10(-2), 2.73×10(-3), 2.72×10(-2), and 3.65×10(-5) under 7Q10 (lowest river flow occurring over a 7day period every 10years) low flow conditions. Because these surfactants have the same toxicological mode of action, the TUs were summed and the aquatic safety for anionic surfactants as a whole was assessed. At the 90th percentile level under the conservative 7Q10 low flow conditions the forecasted TUs were 4.21×10(-2) which indicates that there is a significant margin of safety for the class of anionic surfactants in US aquatic environments.

  14. Hexadecyltrimethylammonium bromide micellization in glycine, diglycine, and triglycine aqueous solutions as a function of surfactant concentration and temperatures

    Science.gov (United States)

    Ali, Anwar; Malik, Nisar Ahmad; Uzair, Sahar; Ali, Maroof; Ahmad, Mohammad Faiz

    2014-06-01

    Micellization behavior of hexadecyltrimethylammonium bromide (HTAB) was investigated conductometrically in aqueous solutions containing 0.02 mol kg-1glycine (Gly), diglycine (Gly-Gly), and triglycine (Gly-Gly-Gly) as a function of surfactant concentration at different temperatures. The critical micelle concentration (CMC) of HTAB exhibits a decreasing trend as the number of carbon atoms increases from Gly to Gly-Gly-Gly, favoring the micelle formation. The values of CMC and the degree of counterion dissociation of the micelles were utilized to evaluate the standard free energy for transferring the surfactant hydrophobic chain out of the solvent to the interior of the micelle, Δ G {HP/○}, free energy associated with the surface contributions, Δ G {S/○}, standard free energy, Δ G {m/○}, enthalpy, Δ H {m/○}, and entropy, Δ S {m/○} of micellization were also calculated. The results show that the micellization of HTAB in aqueous solutions as well as in aqueous Gly/Gly-Gly/Gly-Gly-Gly solutions is primarily governed by the entropy gain due to the transfer of the hydrophobic groups of the surfactant from the solvent to the interior part of the micelle. The CMC obtained by fluorometric method is in close agreement with those obtained conductometrically. Furthermore, decrease in the I 1/ I 3 ratio of pyrene fluorescence intensity suggests the solubilization of the additives by the surfactant micelles and that this solubilization increases as the hydrophobicity increases from Gly to Gly-Gly-Gly.

  15. Evaluating the accuracy of the colorimetric method of determing the concentration of nonionogenic surfactant, with use of thiocyanocobaltammonium

    Energy Technology Data Exchange (ETDEWEB)

    Safiullina, L.A.; Konyukhova, T.Z.; Shtangeyev, A.L.; Tarasova, N.I.

    1981-01-01

    An examination is made of the results of evaluating the accuracy of the colorimetric method of determining the concentration of nonionogenic surfactants (NPAV) and influence on the results of analysis of a number of factors (time from the beginning of making the analysis, method of extraction, admixtures of ions of iron, etc.). A technique is pinpointed for analysis, and sensitivity of the method is established for determining the NPAV with the use of TCCA.

  16. Cyclic voltammetric technique for the determination of the critical micelle concentration of surfactants, self-diffusion coefficient of micelles, and partition coefficient of an electrochemical probe

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, A.B.; Nair, B.U. (Central Leather Research Inst., Madras (India))

    1991-10-31

    Critical micelle concentrations (cmc) of cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC) surfactants in aqueous solution have been determined by using the cyclic voltammetric technique. (Co(en){sub 3})(ClO{sub 4}){sub 3} has been used as the redox-active electrochemical probe. The cmc values so obtained for the surfactants were found to be in good agreement with the literature values. The partition coefficient, K, of the electrochemical probe between water and surfactants in nonmicellar and micellar states was estimated using the peak current, i{sub p} and half-wave potential, E{sub 1/2} values. The self-diffusion coefficient, D{sub m}, interaction parameter, k{sub f}, and hydrodynamic radius of the micelles were also estimated. The results suggest that the probe is sensitive to the nature of surfactant as well as surfactant concentration.

  17. Analyzing freely dissolved concentrations of cationic surfactant utilizing ion-exchange capability of polyacrylate coated solid-phase microextraction fibers.

    Science.gov (United States)

    Chen, Yi; Droge, Steven T J; Hermens, Joop L M

    2012-08-24

    A 7-μm polyacrylate (PA) coated fiber was successfully employed to determine freely dissolved concentrations of cationic surfactants by solid-phase microextraction (SPME) and utilizing the capability of the PA-coating to sorb organic cations via ion-exchange at carboxylic groups. Measured fiber-water partitioning coefficients (K(fw)) were constant below a fiber loading of 2mmol per liter polyacrylate, allowing for simple and accurate analysis in a concentration range that is relevant from a risk assessment point of view. Ion-exchange was confirmed to be the main sorption mechanism because of a decreasing K(fw) with either higher CaCl(2) concentrations or lower pH, and maximum fiber uptake at the polyacrylate cation-exchange capacity (CEC, at 30mmol/L PA). Fiber-water sorption isotherms were established in various aqueous media in toxicological relevant concentrations. The developed SPME method has a high potential for application in ecotoxicological studies, as demonstrated in sorption studies with humic acid in different electrolyte solutions at aqueous concentrations down to the sub nM range. Cationic surfactant sorption affinities for humic acid also depend on medium composition but are orders of magnitude higher than to the PA fiber on a sorbent weight basis.

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

    Science.gov (United States)

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

    2016-04-01

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

  19. Discourse of the form and concentration of surfactants to ensure the sustainability foam-emulsive products

    Directory of Open Access Journals (Sweden)

    Oleg

    2015-05-01

    Full Text Available Introduction. Development of dry mixes for making spumy and emulsion products are topical, because nowadays there is a tendency to minimize the time spent on the process of cooking, which is achieved by the use of semi finished products high degree of readiness. Materials and methods. Foaming ability was determined by the method of multiplicity of the foam, the stability of unstable foam-by the half-life method of foam, highly resistant foam - as a ratio of the height of the column of foam after exposure for 24 hours. Results. Was determined the influence of sunflower oil on the foaming ability and half-life foam of systems «sodium caseinate-oil». It was found that getting systems with high index of foaming capacity and foam stability in the presence of oil in the system is impossible without the use of low molecular weight surfactants. Substantiated recommendations regarding the feasibility of using two surfactants in systems «sodium caseinate-surfactants-oil», which provide the necessary kinship surfaces air, fat and water phases. it has been found that the use of 2,5...3,5% mono-and diglycerides of fatty acid sand Lecithin’s 0.15...0.25% in the content of sodium caseinate about 0.5% allows to receive the stable foam-emulsive systems containing sunflower oil 7...8% and foaming ability about 640±1%. Conclusions. It is established that for ensuring high indicators foaming capacity and stability of foam-emulsive systems required the use of low-molecular surfactants. The research results, is recommended to use when developing technology of foam-emulsive products.

  20. Discourse of the form and concentration of surfactants to ensure the sustainability foam-emulsive products

    Directory of Open Access Journals (Sweden)

    O. Kotlyar

    2015-05-01

    Full Text Available Introduction. Development of dry mixes for making spumy and emulsion products are topical, because nowadays there is a tendency to minimize the time spent on the process of cooking, which is achieved by the use of semi finished products high degree of readiness. Materials and methods. Foaming ability was determined by the method of multiplicity of the foam, the stability of unstable foam-by the half-life method of foam, highly resistant foam - as a ratio of the height of the column of foam after exposure for 24 hours. Results. Was determined the influence of sunflower oil on the foaming ability and half-life foam of systems «sodium caseinate-oil». It was found that getting systems with high index of foaming capacity and foam stability in the presence of oil in the system is impossible without the use of low molecular weight surfactants. Substantiated recommendations regarding the feasibility of using two surfactants in systems «sodium caseinate-surfactants-oil», which provide the necessary kinship surfaces air, fat and water phases. it has been found that the use of 2,5...3,5% mono-and diglycerides of fatty acid sand Lecithin’s 0.15...0.25% in the content of sodium caseinate about 0.5% allows to receive the stable foam-emulsive systems containing sunflower oil 7...8% and foaming ability about 640±1%. Conclusions. It is established that for ensuring high indicators foaming capacity and stability of foam-emulsive systems required the use of low-molecular surfactants. The research results, is recommended to use when developing technology of foam-emulsive products. Introduction

  1. Edge-wave-driven durable variations in the thickness of the surfactant film and concentration of surface floats

    Energy Technology Data Exchange (ETDEWEB)

    Averbukh, Elena [Nizhny Novgorod State Technical University n.a. R.E. Alekseev, Minin St. 24, 603950 Nizhny Novgorod (Russian Federation); Kurkina, Oksana, E-mail: okurkina@hse.ru [Nizhny Novgorod State Technical University n.a. R.E. Alekseev, Minin St. 24, 603950 Nizhny Novgorod (Russian Federation); National Research University Higher School of Economics, 25/12 Bol' shaya Pecherskaya St., 603155 Nizhny Novgorod (Russian Federation); Kurkin, Andrey [Nizhny Novgorod State Technical University n.a. R.E. Alekseev, Minin St. 24, 603950 Nizhny Novgorod (Russian Federation); Soomere, Tarmo, E-mail: soomere@cs.ioc.ee [Institute of Cybernetics at Tallinn University of Technology, Akadeemia tee 21, 12618 Tallinn (Estonia); Estonian Academy of Sciences, Kohtu 6, 10130 Tallinn (Estonia)

    2014-01-03

    By employing a simple model for small-scale linear edge waves propagating along a homogeneous sloping beach, we demonstrate that certain combinations of linear wave components may lead to durable changes in the thickness of the surfactant film, equivalently, in the concentration of various substances (debris, litter) floating on the water surface. Such changes are caused by high-amplitude transient elevations that resemble rogue waves and occur during dispersive focusing of wave fields with a continuous spectrum. This process can be treated as an intrinsic mechanism of production of patches in the surface layer of an otherwise homogeneous coastal environment impacted by linear edge waves.

  2. Effect of surfactant concentration on characteristics of mesoporous bioactive glass prepared by evaporation induced self-assembly process

    Science.gov (United States)

    Shih, Chi-Chung; Chien, Chi-Sheng; Kung, Jung-Chang; Chen, Jian-Chih; Chang, Shy-Shin; Lu, Pei-Shan; Shih, Chi-Jen

    2013-01-01

    Mesoporous bioactive glasses were prepared by the evaporation-induced self-assembly method. The main objective of the present study is to determine the effect of surfactant concentration on the synthesis of SiO2-CaO-P2O5 mesoporous bioactive glasses; the characterization techniques used include X-ray diffraction, scanning electron microscopy and nitrogen adsorption and desorption isotherms. The results show that the specific surface area initially increased with increasing surfactant concentrations in the range of 2.1-9.1 wt% and significantly decreased from 328.7 to 204.0 m2/g in the concentration range of 9.1-12.5 wt%. For texture evaluation, the selected area electron diffraction patterns of the mesoporous bioactive glass precursor gels (9.1 wt% F127) calcined at different temperatures were analyzed; these patterns support the notion that some glassy structures in bioactive glasses become crystalline following heat treatment. The scanning electron microscopy images and X-ray diffraction patterns obtained agree with the inductively coupled plasma with atomic emission spectroscopy results as the mesoporous bioactive glasses can induce the formation of an apatite-like layer on their surface in SBF, even after short soaking periods.

  3. Synthesis and Characterization of Nanoporous Carbon Materials; The Effect of Surfactant Concentrations and Salts

    Directory of Open Access Journals (Sweden)

    Shokoofeh Geranmayeh

    2011-01-01

    Full Text Available Nanoporous carbon framework was synthesized using phenol and formaldehyde as carbon precursors and triblock copolymer (pluronic F127 as soft template via evaporation induced self-assembly. Hexagonal mesoporous carbon with specific surface area of 350 m2/g through optimizing the situation was obtained. The effects of different surfactant/phenol molar ratio and presence of salts on specific surface area, pore size and pore volume for all the prepared samples were studied by means of the Brunauer-Emmett-Teller (BET formalism, powder X-ray diffraction technique and FT-IR spectroscopy.

  4. Soil flushing of cresols contaminated soil: application of nonionic and ionic surfactants under different pH and concentrations.

    Science.gov (United States)

    Gitipour, Saeid; Narenjkar, Khadijeh; Sanati Farvash, Emad; Asghari, Hossein

    2014-01-01

    In this study, the viability of soil flushing on the removal of cresols (meta-, ortho-, and para-cresols) from contaminated soil has been investigated. High production and distribution of cresols in the environment indicate their potential for a widespread exposure to humans. The presence of these compounds in soil could cause a significant threat to environment, as they are toxic and refractory in nature. Cresols are persistent chemicals which are classified by the United State Environmental Protection Agency (U.S.EPA) as Group C, possible human carcinogens. Soil flushing is one of the soil remediation technologies which could by applied for treatment of hydrocarbon contaminated soil. Flushing of the contaminated soil samples was carried out by using sodium dodecyl sulfate (SDS) and Triton X-100 surfactant solutions at the concentrations of 0.1%, 0.2%, 0.3%, and 0.4% (W/W). Three acidic, neutral, and alkaline environments were utilized by adjusting pH of the washing solutions at 3, 7 and 12 to evaluate the effect of washing environment in removing cresols. The results of this research denote that the highest removal efficiencies of 79.6% and 83.51% were achieved for m-cresol and total o- and p-cresols, respectively, under the alkaline environment of pH12 at 0.4% (W/W) SDS concentration. Regarding performance of Triton X-100, the removal efficiencies of 80.26% and 80.14% for the above cresols were attained under similar conditions. Hence, illustrating the effectiveness of surfactants in soil flushing remediation of cresols contaminated soil.

  5. The effects of GH and hormone replacement therapy on serum concentrations of mannan-binding lectin, surfactant protein D and vitamin D binding protein in Turner syndrome

    DEFF Research Database (Denmark)

    Gravholt, Claus Højbjerg; Leth-Larsen, Rikke; Lauridsen, Anna Lis

    2004-01-01

    function. In the present study we examined whether GH or hormone replacement therapy (HRT) in Turner syndrome (TS) influence the serum concentrations of MBL and two other proteins partaking in the innate immune defence, surfactant protein D (SP-D) and vitamin D binding protein (DBP). DESIGN: Study 1...

  6. THE CONCENTRATION OF SURFACTANT PROTEIN-A IN AMNIOTIC FLUID DECREASES IN SPONTANEOUS HUMAN PARTURITION AT TERM

    Science.gov (United States)

    Chaiworapongsa, Tinnakorn; Hong, Joon-Seok; Hull, William M.; Kim, Chong Jai; Gomez, Ricardo; Mazor, Moshe; Romero, Roberto; Whitsett, Jeffrey A.

    2012-01-01

    OBJECTIVE The fetus is thought to play a central role in the onset of labor. Pulmonary surfactant protein (SP)-A, secreted by the maturing fetal lung, has been implicated in the mechanisms initiating parturition in mice. The present study was conducted to determine whether amniotic fluid concentrations of SP-A and SP-B change during human parturition. STUDY DESIGN Amniotic fluid SP-A and SP-B concentrations were measured with sensitive and specific ELISA in the following groups of pregnant women: 1) mid-trimester of pregnancy between 15th and 18th weeks of gestation (n=29); 2) term pregnancy not in labor (n=28); and 3) term pregnancy in spontaneous labor (n=26). Non-parametric statistics were used for analysis. RESULTS SP-A was detected in all amniotic fluid samples. SP-B was detected in 24.1% (7/29) of mid-trimester samples and in all samples at term. The median amniotic fluid concentration of SP-A and SP-B were significantly higher in women at term than in women in the mid-trimester (SP-A term no labor: median 5.6 μg/ml, range 2.2–15.2 μg/ml vs. mid-trimester: median 1.64 μg/ml, range 0.1–4.7 μg/ml; and SP-B term no labor: median 0.54 μg/ml, range 0.17–1.99 μg/ml vs. mid-trimester: median 0 μg/ml, range 0–0.35 μg/ml; both plabor was significantly lower than that in women at term not in labor (term in labor: median 2.7 μg/ml, range 1.2–10.1 μg/ml vs. term no labor: median 5.6 μg/ml, range 2.2–15.2 μg/ml; plabor and those not in labor (term in labor: median 0.47 μg/ml range 0.04–1.32 μg/ml vs. term no labor: median 0.54 μg/ml range 0.17–1.99 μg/ml; p=0.2). CONCLUSION The amniotic fluid concentration of surfactant protein-A decreases in spontaneous human parturition at term. PMID:18828058

  7. Adsorption of proteins at the solution/air interface influenced by added nonionic surfactants at very low concentrations for both components. 3. Dilational surface rheology.

    Science.gov (United States)

    Fainerman, V B; Aksenenko, E V; Lylyk, S V; Lotfi, M; Miller, R

    2015-03-05

    The influence of the addition of the nonionic surfactants C12DMPO, C14DMPO, C10OH, and C10EO5 at concentrations between 10(-5) and 10(-1) mmol/L to solutions of β-casein (BCS) and β-lactoglobulin (BLG) at a fixed concentration of 10(-5) mmol/L on the dilational surface rheology is studied. A maximum in the viscoelasticity modulus |E| occurs at very low surfactant concentrations (10(-4) to 10(-3) mmol/L) for mixtures of BCS with C12DMPO and C14DMPO and for mixtures of BLG with C10EO5, while for mixture of BCS with C10EO5 the value of |E| only slightly increased. The |E| values calculated with a recently developed model, which assumes changes in the interfacial molar area of the protein molecules due to the interaction with the surfactants, are in satisfactory agreement with experimental data. A linear dependence exists between the ratio of the maximum modulus for the mixture to the modulus of the single protein solution and the coefficient reflecting the influence of the surfactants on the adsorption activity of the protein.

  8. Facile method for fabrication of surfactant-free concentrated CeO2 sols

    Science.gov (United States)

    Shcherbakov, Alexander B.; Teplonogova, Maria A.; Ivanova, Olga S.; Shekunova, Taisiya O.; Ivonin, Ivan V.; Baranchikov, Alexander Ye; Ivanov, Vladimir K.

    2017-05-01

    We report a facile method for fabrication of highly concentrated electrostatically stabilized colloidal solutions containing ultra-small cerium (IV) oxide crystallites having a narrow size distribution (3-5 nm according to x-ray diffraction, and 10-30 nm according to dynamic light scattering). The proposed method comprises hydrothermal treatment of ceric ammonium nitrate aqueous solutions having concentrations over 0.2 M, in the temperature range of 80-100 °C, and the formation of nanoceria sediments, which can be easily peptized in both protic (water, isopropanol) and aprotic (DMF) media, forming stable and transparent CeO2 sols.

  9. Comparison between the interactions of the cationic surfactant DODAB with xanthan and galactomannan.

    Science.gov (United States)

    Kaminski, Gabriel A T; Sierakowski, Maria Rita; Pontarolo, Roberto; de Freitas, Rilton Alves

    2015-01-22

    The interactions of the cationic surfactant DODAB with anionic xanthan (XAN) and nonionic galactomannan (GMC) polysaccharides in solution were investigated using tensiometry, differential scanning microcalorimetry (μ-DSC), zeta potential and dynamic light scattering (DLS) techniques and by the calculated thermodynamic parameters of ΔG(ves)(0), ΔG(ads)(0), Γ(max) and a(min). The surfactant formed large unilamellar vesicles (LUV) that aggregated with both the polymers in solution. Increasing DODAB concentrations resulted in greater and greater DODAB-XAN aggregates, high turbidity and even precipitation, while DODAB-GMC aggregates remained equal sized, clear solution and no precipitation observed. Further addition of DODAB to XAN solution was able to resuspend the precipitates. The interactions with both polysaccharides resulted in a more spontaneous adsorption of the DODAB-polymer aggregates at the air/solution interface with lower surfactant population.

  10. Effect of surfactant/water ratio and reagents' concentration on size distribution of manganese carbonate nanoparticles synthesized by microemulsion mediated route

    Science.gov (United States)

    Granata, Giuseppe; Pagnanelli, Francesca; Nishio-Hamane, Daisuke; Sasaki, Takehiko

    2015-03-01

    In this work nanoparticles of manganese carbonate were produced by microemulsion-mediated route at room temperature, without any post-thermal treatment. All produced samples were characterized by XRD and by TEM and obtained images were analyzed in order to evaluate particle size distribution, mean size and polydispersity (variance). The influence of water-surfactant molar ratio and concentration of reagents were investigated in the range 5-7.5 and 0.25-1.0 M, respectively, according to factorial design. Significant effects on particle mean size and polydispersity were assessed by statistical analysis. Results showed that by increasing the water-surfactant molar ratio from 5 to 7.5, the average particle size increased from less than 10 nm to around 100 nm, and the standard deviation increased from less than 5 nm to 35 nm. Statistical analysis put in evidence that water-surfactant molar ratio has significant positive effect on both mean and variance of particle size. Concentration of reactants, in the investigated range, did not influence mean size of particles, while significant changes of variance were observed: passing from 0.25 to 1 M concentration, variances of particle size increased for w = 5 and for w = 6.25, while decreased for w = 7.5.

  11. Efficient control system for low-concentration inorganic gases from a process vent stream: application of surfactants in spray and packed columns.

    Science.gov (United States)

    Chein, Hungmin; Aggarwal, Shankar G; Wu, Hsin-Hsien

    2004-11-01

    Control of low-concentration pollutants from a semiconductor process vent stream using a wet-scrubbing technique is a challenging task to meet Taiwan environmental emission standards. An efficient wet-scrubber is designed on a pilot scale and tested to control low concentration acid and base waste-gas emission. The scrubber system consisted of two columns, i.e., a fine spray column [cutoff diameter (based on volume), Dv(50) = 15.63 microm; Sauter mean diameter (SMD) = 7.62 microm], which is especially efficient for NH3 removal as the pH of the spraying liquid is approximately 7 followed by a packed column with a scrubbing liquid pH approximately 9.0 mainly for acids removal. It is observed that use of the surfactants in low concentration about 10(-4) M and 10(-7) M in the spray liquid and in the scrubbing liquid, respectively, remarkably enhances the removal efficiency of the system. A traditional packed column (without the spray column and the surfactant) showed that the removal efficiencies of NH3, HF, and HCl for the inlet concentration range 0.2 to 3 ppm were (n = 5) 22.6+/-3.4%, 43.4+/-5.5%, and 40.4+/-7.4%, respectively. The overall efficiencies of the proposed system (the spray column and the packed column) in the presence of the surfactant in the spray liquid and in the scrubbing liquid forthese three species were found to increase significantly (n = 5) from 60.3+/-3.6 to 82.8+/-6.8%, 59.1+/-2.7 to 83.4+/-4.2%, and 56.2+/-7.3 to 81.0+/-6.7%, respectively. In this work, development of charge on the gas-liquid interface due to the surfactants has been measured and discussed. It is concluded that the presence of charge on the gas-liquid interface is the responsible factor for enhancement of the removal efficiency (mass-transfer in liquid phase). The effects of the type of surfactants, their chain length, concentration in liquid, etc. on the removal efficiency are discussed. Since the pilot tests were performed under the operating conditions similar to most of

  12. Design of Agglomerated Crystals of Ibuprofen During Crystallization: Influence of Surfactant

    Directory of Open Access Journals (Sweden)

    Maryam Maghsoodi

    2011-01-01

    Full Text Available Objective(sIbuprofen is a problematic drug in tableting, and dissolution due to its poor solubility, hydrophobicity, and tendency to stick to surface. Because of the bad compaction behavior ibuprofen has to be granulated usually before tableting. However, it would be more satisfactory to obtain directly during the crystallization step crystalline particles that can be directly compressed and quickly dissolved. Materials and Methods Crystallization of ibuprofen was carried out using the quasi emulsion solvent diffusion method in presence of surfactant (sodium lauryl sulfate (SLS, Tween 80. The particles were characterized by differential scanning calorimetry (DSC, powder X-ray diffraction (XRPD and were evaluated for particle size, flowability, drug release and tableting behavior. ResultsIbuprofen particles obtained in the presence of surfactants consisted of numerous plate- shaped crystals which had agglomerated together as near spherical shape. The obtained agglomerates exhibited significantly improved micromeritic properties as well as tableting behavior than untreated drug crystals. The agglomerates size and size distribution was largely controlled by surfactant concentration, but there was no significant influence found on the tableting properties. The dissolution tests showed that the agglomerates obtained in presence of SLS exhibited enhanced dissolution rate while the agglomerates made in the presence of Tween 80 had no significant impact on dissolution rate of ibuprofen in comparison to untreated sample. The XRPD and DSC results showed that during the agglomeration process, ibuprofen did not undergo any polymorphic changes.Conclusion The study highlights the influence of surfactants on crystallization process leading to modified performance.

  13. Detection of the critical micelle concentration of cationic and anionic surfactants based on aggregation-induced emission property of hexaphenylsilole derivatives

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    We report a fluorescence "turn-on" method to detect the critical micelle concentration (CMC) of surfactants. This method works well for both cationic and anionic surfactants. It employs an unprecedented mechanism (aggregation-induced emission, or AIE) to determine the CMC values, and the results are consistent with the data obtained by the classical techniques. In addition, this method renders the convenient detection of the CMC values. Any large and professional instruments are unnecessary, instead, a portable UV lamp and an ultrasonic generator are enough to carry out the detection in an ordinary laboratory. Considering that micelles are interesting entities and have found applications in many important fields such as emulsion polymerization, template of nanosized materials synthesis, controllable drug delivery and macromolecular self-assembling. Our experimental results may offer a facile, sensitive and promising method to detect the formation of micelles constructed by the new amphiphilic molecules and macromolecules.

  14. Detection of the critical micelle concentration of cationic and anionic surfactants based on aggregation-induced emission property of hexaphenylsilole derivatives

    Institute of Scientific and Technical Information of China (English)

    TANG Li; JIN JiaKe; ZHANG Shuang; MAO Yu; SUN JingZhi; YUAN WangZhang; ZHAO Hui; XU HaiPeng; QIN AnJun; TANG Ben Zhong

    2009-01-01

    We report a fluorescence "turn-on" method to detect the critical micelle concentration (CMC) of sur-factants. This method works well for both cationic and anionic surfactants. It employs an unprece-dented mechanism (aggregation-induced emission, or AIE) to determine the CMC values, and the re-suits are consistent with the data obtained by the classical techniques. In addition, this method renders the convenient detection of the CMC values. Any large and professional instruments are unnecessary, instead, a portable UV lamp and an ultrasonic generator are enough to carry out the detection in an ordinary laboratory. Considering that micelles are interesting entities and have found applications in many important fields such as emulsion polymerization, template of nanoeized materials synthesis, controllable drug delivery and macromolecular self-assembling. Our experimental results may offer a facile, sensitive and promising method to detect the formation of micelles constructed by the new amphiphilic molecules and macromolecules.

  15. DSC Study of Collagen in Disc Disease

    OpenAIRE

    S. Skrzyński; Sionkowska, A.; Marciniak, A.

    2009-01-01

    Differential scanning calorimetry (DSC) has been used to estimate the effect of disc disease on the collagen helix-coil transition and morphology for tissue extracted from patients during surgical operation. Forty discs were obtained from patients with degenerative disc disease undergoing surgery for low back pain. The patients were in the age between 20 and 70 years old. The specimens were kept wet during DSC experiment. The data allow the comparison between thermal stability of collagen ti...

  16. Performance Evaluation of DSC Windows for Buildings

    Directory of Open Access Journals (Sweden)

    Jun-Gu Kang

    2013-01-01

    Full Text Available Interest in BIPV systems with dye-sensitized solar cells (DSCs that can replace building windows has increased for zero energy buildings. Although DSCs have lower efficiency in terms of electricity generation than silicon solar cells, they allow light transmission and application of various colors; they also have low production costs, which make them especially suitable for BIPV systems. DSC research is interdisciplinary, involving electrical, chemical, material, and metal engineering. A considerable amount of research has been conducted on increasing the electrical efficiency of DSC and their modules. However, there has not been sufficient research on building applications of DSC systems. The aim of this study is to evaluate the optical performance and thermal performance of DSC windows in buildings. For this study, DSC experimental models with different thicknesses and dye colors were manufactured, and their optical properties, such as transmittance and reflectivity, were measured by a spectrometer. The thermal and optical characteristics of double-glazed windows with DSC were analyzed with a window performance analysis program, WINDOW 6.0.

  17. Surfactant recovery from water using foam fractionation

    Energy Technology Data Exchange (ETDEWEB)

    Tharapiwattananon, N.; Osuwan, S. [Chulalongkorn Univ., Bangkok (Thailand); Scamehorn, J.F. [Inst. of Oklahoma, Norman, OK (United States)] [and others

    1996-05-01

    The purpose of this study was to investigate the use of foam fractionation to recover surfactant from water. A simple continuous mode foam fractionation was used and three surfactants were studied (two anionic and one cationic). The effects of air flow rate, foam height, liquid height, liquid feed surfactant concentration, and sparger porosity were studied. This technique was shown to be effective in either surfactant recovery or the reduction of surfactant concentration in water to acceptable levels. As an example of the effectiveness of this technique, the cetylpyridinium chloride concentration in water can be reduced by 90% in one stage with a liquid residence time of 375 minutes. The surfactant concentration in the collapsed foam is 21.5 times the feed concentration. This cationic surfactant was easier to remove from water by foam fractionation than the anionic surfactants studied.

  18. Synthesis and Characterization of Zirconia Nanocrystallites by Cationic Surfactant and Anionic Surfactant

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Study on nanomaterials has attracted great interests in recent years. In this article,zirconia nanocrystallites of different structures have been successfully synthesized via hydrothermal methods with cationic surfactant (CTAB) and anionic surfactant (SDS), respectively. Differential Scanning Calorimeter (DSC-TG), X-ray Diffractometer (XRD), Transmission Electron Microscope (TEM), Ultraviolet-Visible (UV-vis) and N2 adsorption-desorption analyses are used for their structure characteristics. The results show that the cationic surfactant has a distinctive direction effect on the formation of zirconia nanocrystallites, while the anionic surfactant has a self-assembly synergistic effect on them. The sample synthesized with the cationic surfactant presents good dispersion with the main phase of tetragonal zirconia, and the average nanocryst al size is around 15nm after calcination at 500 ℃. While the sample synthesized with the anionic surfactant exhibits a worm-like mesoporous structure with pure tetragonal phase after calcination at 500 ℃ and with good thermal stability.

  19. Influence of surfactant concentration on counter-ion induced solubility of poly(pyridine-2,5-diyl)

    Institute of Scientific and Technical Information of China (English)

    IMIT Mokhtar; YAMAMOTO Takakazu; IMIN Patigul

    2005-01-01

    Protonating the pyridine rings of poly(pyridine-2,5-diyl) with dodecybenzenesulfonic acid and camphorsulphonic acid produces polymer materials which can be dissolved in chloroform (in contrast to the unprotonated polymer, which can only be dissolved in strong acids such as formic acid) and allows mixing the protonated polymers with other chloroform soluble conjugated polymers for use in electronic devices. The protonating behavior of poly(pyridine-2,5-diyl) with two kinds of surfactants is different in some levels. Dodecybenzenesulfonic acid has higher protonating ability than camphorsulphonic acid.

  20. Interactions of phenol with cationic micelles of hexadecyltrimethylammonium bromide studied by titration calorimetry, conductimetry, and 1H NMR in the range of low additive and surfactant concentrations.

    Science.gov (United States)

    Chaghi, Radhouane; de Ménorval, Louis-Charles; Charnay, Clarence; Derrien, Gaëlle; Zajac, Jerzy

    2008-10-01

    Interactions of phenol (PhOH) with micellar aggregates of hexadecyltrimethylammonium bromide (HTAB) in aqueous solutions at surfactant concentrations close to the CMC and phenol contents of 1, 5, or 10 mmol kg(-1) have been investigated at 303 K by means of titration calorimetry, solution conductimetry, and (1)H NMR spectroscopy. Estimates of the main thermodynamic parameters related to HTAB micellization were made for PhOH/HTAB/H(2)O systems based on the specific conductivity measurements and calorimetric determination of the cumulative enthalpy of dilution as functions of the surfactant concentration at a fixed additive content. The combined analysis of the results obtained in H(2)O solutions pointed to the preferential location of PhOH in the outer micelle parts by an enthalpy-driven mechanism. Additional PhOH molecules were located increasingly deeper within the micelle core. The (1)H NMR study of PhOH solubilization by 1.5 mmol kg(-1) HTAB solutions in D(2)O indicated that the two categories of the solubilization site became saturated with the solubilizate already at the lowest additive content. Dissimilar amounts of the solubilized material in H(2)O and D(2)O solutions were ascribed to the difference in the initial micelle structures formed in the two solvents, as inferred from calorimetry and (1)H NMR studies of the HTAB micellization in D(2)O and H(2)O.

  1. New surfactant phosphine ligands and platinum(II) metallosurfactants. Influence of metal coordination on the critical micelle concentration and aggregation properties.

    Science.gov (United States)

    Parera, Elisabet; Comelles, Francesc; Barnadas, Ramon; Suades, Joan

    2010-01-19

    We have prepared the first platinum(II) metallosurfactants from a new family of linear surfactant phosphines Ph(2)P(CH(2))(n)SO(3)Na {1 (n = 2), 2 (n = 6), and 3 (n = 10)}, which were synthesized by reaction between the halosulfonates X(CH(2))(n)SO(3)Na and sodium diphenylphosphide. The metallosurfactants cis-[PtCl(2)L(2)] (L = 1-3) were obtained after reaction between the phosphines and PtCl(2) in dimethylsulfoxide. All compounds were fully characterized by the usual methods {NMR ((1)H, (13)C, (31)P, (195)Pt), IR, MS-ESI and HRMS}. By exploring the surfactant properties of phosphines 1-3 and their respective platinum metallosurfactants cis-[PtCl(2)L(2)] (L = 1-3) through surface tension measurements, dynamic light scattering spectroscopy, and cryo-TEM microscopy, we were able to analyze the influence of the metal coordination on the critical micelle concentration (cmc) and the aggregation properties. The cmc values of platinum metallosurfactants were considerably lower than those obtained for the free phosphines 1-3. This behavior could be understood by an analogy between the structure of cis-[PtCl(2)L(2)] complexes and bolaform surfactants. The calculated values of area per molecule also showed different tendencies between 1-3 and cis-[PtCl(2)L(2)] complexes, which could be explained on the basis of the possible conformations of these compounds in the air-water interface. The study of aggregates by dynamic light scattering spectroscopy and cryo-TEM microscopy showed the formation of spherical disperse medium size vesicles in all cases. However, substantial differences were observed between the three free phosphines (the population of micellar aggregates increased with long chain length) and also between phosphines and their respective metallosurfactants.

  2. Determination of lead in water resources by flame atomic absorption spectrometry after pre-concentration with ammonium pyrrolidinedithiocarbamate immobilized on surfactant-coated alumina

    Directory of Open Access Journals (Sweden)

    SAYED MORTEZA TALEBI

    2007-06-01

    Full Text Available Arapid, simple, and sensitive procedure based on modified solid phase extraction was developed for the pre-concentration and determination of trace amount of lead in water resources. Lead was reacted with ammonium pyrrolidinedithiocarbamate (APDC to make a complex. The complex was then collected in a column packed with surfactant-coated alumina. The parameters affecting the collection efficiency and desorption rate of the lead complexes from the column were investigated and optimized. The collection efficiency of the lead complex on the adsorbent was excellent under the optimized conditions. The results obtained from the recovery test showed the capability and reliability of the method for the analysis of trace amounts of lead. The proposed pre-concentration procedure made it possible to apply conventional flame atomic absorption spectrometry (FAAS for the sensitive determination of trace amounts of lead in water resources.

  3. Differential scanning calorimetry (DSC) of semicrystalline polymers.

    Science.gov (United States)

    Schick, C

    2009-11-01

    Differential scanning calorimetry (DSC) is an effective analytical tool to characterize the physical properties of a polymer. DSC enables determination of melting, crystallization, and mesomorphic transition temperatures, and the corresponding enthalpy and entropy changes, and characterization of glass transition and other effects that show either changes in heat capacity or a latent heat. Calorimetry takes a special place among other methods. In addition to its simplicity and universality, the energy characteristics (heat capacity C(P) and its integral over temperature T--enthalpy H), measured via calorimetry, have a clear physical meaning even though sometimes interpretation may be difficult. With introduction of differential scanning calorimeters (DSC) in the early 1960s calorimetry became a standard tool in polymer science. The advantage of DSC compared with other calorimetric techniques lies in the broad dynamic range regarding heating and cooling rates, including isothermal and temperature-modulated operation. Today 12 orders of magnitude in scanning rate can be covered by combining different types of DSCs. Rates as low as 1 microK s(-1) are possible and at the other extreme heating and cooling at 1 MK s(-1) and higher is possible. The broad dynamic range is especially of interest for semicrystalline polymers because they are commonly far from equilibrium and phase transitions are strongly time (rate) dependent. Nevertheless, there are still several unsolved problems regarding calorimetry of polymers. I try to address a few of these, for example determination of baseline heat capacity, which is related to the problem of crystallinity determination by DSC, or the occurrence of multiple melting peaks. Possible solutions by using advanced calorimetric techniques, for example fast scanning and high frequency AC (temperature-modulated) calorimetry are discussed.

  4. Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants

    Directory of Open Access Journals (Sweden)

    Roza Bouchal

    2016-02-01

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

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

    Science.gov (United States)

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

    2016-02-06

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

  6. Morphology and photoluminescence of self-assembled CaWO4:Sm3+ microspheres: effect of pH and surfactant concentration

    Science.gov (United States)

    Ningombam, Goutam Singh; Nongmaithem, Rajmuhon Singh

    2017-03-01

    Self-assembled CaWO4:Sm3+ microspheres were prepared via surfactant (sodium dodecyl sulfate) mediated hydrothermal method. The effect of pH and the concentration of surfactant on the morphology and photoluminescence of the synthesized phosphors have been studied. Samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence spectroscopy. The microspheres were found to have an average size of 1-2 µm. They were mesoporous in nature and constituted of nanocrystals of about 10-30 nm dimension. The TEM images revealed the interlinking framework of the nano-sized constituents which consequently lead to the formation of mesoporous microspheres. The lowering of pH causes a slight reduction in the size of microspheres which could have been attributed to loss of OH from the nanoparticle surface and subsequent retardation in the adsorption of growing molecular CaWO4:Sm3+ units. Also, as pH increases, crystallinity decreases. The increase in amount of SDS reduced the crystallinity of the materials, destroyed the monodispersity of microspheres and lowered the luminescence output. It was found that lower pH and higher monodispersity of microspheres are quite favourable for high luminescence output.

  7. BINDING ISOTHERMS SURFACTANT-PROTEINS

    Directory of Open Access Journals (Sweden)

    Elena Irina Moater

    2011-12-01

    Full Text Available The interactions between surfactants and proteins shows some similarities with interactions between surfactants and polymers, but the hydrophobic amphoteric nature of proteins and their secondary and tertiary structure components make them different from conventional polymer systems. Many studies from the past about surfactant - proteins bonding used the dialysis techniques. Other techniques used to determine the binding isotherm, included ultrafiltration, ultracentrifugation, potentiometry, ion-selective electrode method and surface tension. High affinity isotherms which are typical of an anionic surfactant - protein bonding, exhibit an initial increase steep followed by a slow growth region and then a vertical growth above a certain concentration. This isotherm is typical of ionic surfactant to protein binding. Often the high affinity initial bond appears at very low concentrations of surfactant and therefore in some protein-surfactant systems, the exact shape of the isotherm in this region may be missing. The surfactant - protein binding is influenced by a number of variables such as the nature and chain length of surfactant, pH, ionic strength, temperature, nature of this protein and additives.

  8. Surfactant monitoring by foam generation

    Science.gov (United States)

    Mullen, Ken I.

    1997-01-01

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

  9. Evaluation of Clay and Fumed Silica Nanoparticles on Adsorption of Surfactant Polymer during Enhanced Oil Recovery

    National Research Council Canada - National Science Library

    Cheraghian, Goshtasp

    2017-01-01

    .... The effects of nano concentration on static adsorption of surfactant were investigated at variable condition polymer and surfactant concentration and nanoparticles are critical parameters influence...

  10. Surfactant analysis in oil-containing fluids

    Energy Technology Data Exchange (ETDEWEB)

    Gronsveld, J.; Faber, M.J. (Koninklijke Shell Exploratie en Produktie Laboratorium, Rijswijk (Netherlands))

    The total surfactant concentration in aqueous phase samples can be analysed with a potentiometric titration. In enhanced oil recovery research, however, the surfactant is produced not only in aqueous phase samples but also in oleic phase samples. The oleic constituents in the oliec phase samples interfere in the surfactant analysis and, therefore, the titration method has been adapted. (orig.).

  11. Surfactant adsorption to soil components and soils

    NARCIS (Netherlands)

    Ishiguro, Munehide; Koopal, Luuk K.

    2016-01-01

    Soils are complex and widely varying mixtures of organic matter and inorganic materials; adsorption of surfactants to soils is therefore related to the soil composition. We first discuss the properties of surfactants, including the critical micelle concentration (CMC) and surfactant adsorption on

  12. Interaction of nonionic surfactant AEO9 with ionic surfactants

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-guo; YIN Hong

    2005-01-01

    The interaction in two mixtures of a nonionic surfactant AEO9 (C12H25O(CH2CH2O)9H) and different ionic surfactants was investigated. The two mixtures were AEO9/sodium dodecyl sulfate (SDS) and AEO9/cetyltrimethylammonium bromide (CTAB) at molar fraction of AEO9, αAEO9 =0.5. The surface properties of the surfactants, critical micelle concentration (CMC),effectiveness of surface tension reduction (γCMC), maximum surface excess concentration (Гmax) and minimum area per molecule at the air/solution interface (Amin) were determined for both individual surfactants and their mixtures. The significant deviations from ideal behavior (attractive interactions) of the nonionic/ionic surfactant mixtures were determined. Mixtures of both AEO9/SDS and AEO9/CTAB exhibited synergism in surface tension reduction efficiency and mixed micelle formation, but neither exhibited synergism in surface tension reduction effectiveness.

  13. Effect of surfactants on surface activity and rheological properties of type I collagen at air/water interface.

    Science.gov (United States)

    Kezwoń, Aleksandra; Góral, Ilona; Frączyk, Tomasz; Wojciechowski, Kamil

    2016-12-01

    We describe the effect of three synthetic surfactants (anionic - sodium dodecyl sulfate (SDS), cationic - cetyltrimethylammonium bromide (CTAB) and nonionic - Triton X-100 (TX-100)) on surface properties of the type I calf skin collagen at the air/water interface in acidic solutions (pH 1.8). The protein concentration was fixed at 5×10(-6)molL(-1) and the surfactant concentration was varied in the range 5×10(-6)molL(-1)-1×10(-4)molL(-1), producing the protein/surfactant mixtures with molar ratios of 1:1, 1:2, 1:5, 1:10 and 1:20. An Axisymmetric Drop Shape Analysis (ADSA) method was used to determine the dynamic surface tension and surface dilatational moduli of the mixed adsorption layers. Two spectroscopic techniques: UV-vis spectroscopy and fluorimetry allowed us to determine the effect of the surfactants on the protein structure. The thermodynamic characteristic of the mixtures was studied using isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC). Modification of the collagen structure by SDS at low surfactant/protein ratios has a positive effect on the mixture's surface activity with only minor deterioration of the rheological properties of the adsorbed layers. The collagen/CTAB mixtures do not show that pronounced improvement in surface activity, while rheological properties are significantly deteriorated. The mixtures with non-ionic TX-100 do not show any synergistic effects in surface activity.

  14. Switchable Surfactants

    National Research Council Canada - National Science Library

    Yingxin Liu; Philip G. Jessop; Michael Cunningham; Charles A. Eckert; Charles L. Liotta

    2006-01-01

    .... We report that long-chain alkyl amidine compounds can be reversibly transformed into charged surfactants by exposure to an atmosphere of carbon dioxide, thereby stabilizing water/alkane emulsions...

  15. 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.

  16. Interaction of nonionic surfactant AEO9 with ionic surfactants*

    OpenAIRE

    2005-01-01

    The interaction in two mixtures of a nonionic surfactant AEO9 (C12H25O(CH2CH2O)9H) and different ionic surfactants was investigated. The two mixtures were AEO9/sodium dodecyl sulfate (SDS) and AEO9/cetyltrimethylammonium bromide (CTAB) at molar fraction of AEO9, α AEO9=0.5. The surface properties of the surfactants, critical micelle concentration (CMC), effectiveness of surface tension reduction (γ CMC), maximum surface excess concentration (Γ max) and minimum area per...

  17. Correlation between DNAPL distribution area and dissolved concentration in surfactant enhanced aquifer remediation effluent: a two-dimensional flow cell study

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Bin; Li, Huiying; Du, Xiaoming; Zhong, Lirong; Yang, Bin; Du, Ping; Gu, Qingbao; Li, Fasheng

    2016-02-01

    During the process of surfactant enhanced aquifer remediation (SEAR), free phase dense non-aqueous phase liquid (DNAPL) may be mobilized and spread. The understanding of the impact of DNAPL spreading on the SEAR remediation is not sufficient with its positive effect infrequently mentioned. To evaluate the correlation between DNAPL spreading and remediation efficiency, a two-dimensional sandbox apparatus was used to simulate the migration and dissolution process of 1,2-DCA (1,2-dichloroethane) DNAPL in SEAR. Distribution area of DNAPL in the sandbox was determined by digital image analysis and correlated with effluent DNAPL concentration. The results showed that the effluent DNAPL concentration has significant positive linear correlation with the DNAPL distribution area, indicating the mobilization of DNAPL could improve remediation efficiency by enlarging total NAPL-water interfacial area for mass transfer. Meanwhile, the vertical migration of 1,2-DCA was limited within the boundary of aquifer in all experiments, implying that by manipulating injection parameters in SEAR, optimal remediation efficiency can be reached while the risk of DNAPL vertical migration is minimized. This study provides a convenient visible and quantitative method for the optimization of parameters for SEAR project, and an approach of rapid predicting the extent of DNAPL contaminant distribution based on the dissolved DNAPL concentration in the extraction well.

  18. Correlation between DNAPL distribution area and dissolved concentration in surfactant enhanced aquifer remediation effluent: A two-dimensional flow cell study.

    Science.gov (United States)

    Wu, Bin; Li, Huiying; Du, Xiaoming; Zhong, Lirong; Yang, Bin; Du, Ping; Gu, Qingbao; Li, Fasheng

    2016-02-01

    During the process of surfactant enhanced aquifer remediation (SEAR), free phase dense non-aqueous phase liquid (DNAPL) may be mobilized and spread. The understanding of the impact of DNAPL spreading on the SEAR remediation is not sufficient with its positive effect infrequently mentioned. To evaluate the correlation between DNAPL spreading and remediation efficiency, a two-dimensional sandbox apparatus was used to simulate the migration and dissolution process of 1,2-DCA (1,2-dichloroethane) DNAPL in SEAR. Distribution area of DNAPL in the sandbox was determined by digital image analysis and correlated with effluent DNAPL concentration. The results showed that the effluent DNAPL concentration has significant positive linear correlation with the DNAPL distribution area, indicating the mobilization of DNAPL could improve remediation efficiency by enlarging total NAPL-water interfacial area for mass transfer. Meanwhile, the vertical migration of 1,2-DCA was limited within the boundary of aquifer in all experiments, implying that by manipulating injection parameters in SEAR, optimal remediation efficiency can be reached while the risk of DNAPL vertical migration is minimized. This study provides a convenient visible and quantitative method for the optimization of parameters for SEAR project, and an approach of rapid predicting the extent of DNAPL contaminant distribution based on the dissolved DNAPL concentration in the extraction well.

  19. Surfactant Removal Study for Nano-Scale SmCo5 Powder Prepared by High Energy Ball Milling (Postprint)

    Science.gov (United States)

    2014-04-01

    DD-MM-YY) 2. REPORT TYPE 3. DATES COVERED (From - To) April 2014 Interim 19 March 2014 – 31 March 2014 4. TITLE AND SUBTITLE SURFACTANT ...thickness of 300 nm were prepared by high energy ball milling using valeric acid as a surfactant . In order to remove the surfactant the as-milled...investigated. Partial (58%) and nearly complete (96%) surfactant removal was observed by DSC after treatments at 200°C and 400°C, respectively, without oxide

  20. Effects of Interactions Among Surfactants,Water and Oil on Equilibrium Configuration of Surfactant-Water-Oil Systems

    Institute of Scientific and Technical Information of China (English)

    YUAN Yin-quan; SUN Zhi-bo; XIE Yun; ZOU Xian-wu

    2004-01-01

    The distribution and configuration of surfactants at interface in surfactant-water-oil systems have been investigated using discontinuous molecular dynamic simulations. There exists a certain equilibrium concentration of surfactants at interface for the systems with certain interactions among surfactant, water and oil. The interface length and equilibrium morphology of the systems are dependent on the equilibrium concentration of surfactants at interface and the total amount of surfactants. The interaction strengths among surfactant, water and oil determine the equilibrium concentration of surfactants at interface. Three typical configurations of surfactants at interface have been observed: ① surfactant molecules are perpendicular to the interface and arranged closely; ② perpendicular to the interface and arranged at interval of two particles; ③ lie down in the interface partly.

  1. Apparent equilibration time required for surfactant-oil-water systems to emulsify into the morphology imposed by the formulation. Part 2: Effect of sec-butanol concentration and initial location.

    Science.gov (United States)

    Alvarez, Gabriela; Antón, Raquel; Marfisi, Shirley; Márquez, Laura; Salager, Jean-Louis

    2004-06-22

    Winsor type I equilibrated surfactant-oil-water (SOW) systems produce o/w emulsions upon stirring. However, if the surfactant is initially dissolved in the oil phase, the attained type after inmediate emulsification is usually w/o. If the SOW system is partially equilibrated, it could result in a normal o/w emulsion, as if it were fully equilibrated. The minimum contact time for that to happen, the so-called apparent equilibration time tAPE, was previously shown (Langmuir 2002, 18, 607) to strongly depend on formulation, surfactant molecular weight, and oil viscosity. The present report shows that it depends on alcohol concentration and location in the unequilibrated system.

  2. DSC Study of Collagen in Disc Disease

    Directory of Open Access Journals (Sweden)

    S. Skrzyński

    2009-01-01

    Full Text Available Differential scanning calorimetry (DSC has been used to estimate the effect of disc disease on the collagen helix-coil transition and morphology for tissue extracted from patients during surgical operation. Forty discs were obtained from patients with degenerative disc disease undergoing surgery for low back pain. The patients were in the age between 20 and 70 years old. The specimens were kept wet during DSC experiment. The data allow the comparison between thermal stability of collagen tissue from healthy patients and from patients suffering from disc disease. In the paper the comparison between thermal helix-coil transition for collagen fibers from patients suffering from disc disease and collagen fibers from healthy organisms has been discussed. The heating rate has an influence on the position on denaturation temperatures of collagen in disc tissues. Higher helix-coil transition temperature of collagen in degenerated disc suggests that additional intermolecular cross linking of collagen fibers occurs. Denaturation temperatures of collagen in degenerated male disc possess smaller values than in female ones. Disc disease induces changes in collagen structure and leads to formation of additional crosslinks between collagen fibers.

  3. Emulsion Polymerization of Etyl Acrylate: The Effect of Surfactant, Initiator Concentration and PolymerizationTechnique on Particle Size Distribution

    Directory of Open Access Journals (Sweden)

    Nitri Arinda

    2009-04-01

    Full Text Available Emulsion polymerization was conducted using ethyl acrylate monomer. Theeffect of sodium lauryl sulfate concentration, ammonium persulfate concentration, the various of polymerizationtechniques and feeding time to the conversion, particle size and its distribution were observed. The purpose of thisresearch is to obtain the optimum condition of ethyl acrylate homopolymer with particle size around 100 nm, to get theparticle size distribution monodisperse and to get solid content value of the experiment closed to its theoretical value.The optimum condition then could be applied in shell polymerization of core-shell polymers. The results of the researchshowed that semicontinuous technique obtained optimum sodium lauryl sulfate concentration at 20 CMC (criticalmicelle concentration and ammonium persulfate concentration is 3%. By using batch technique that the biggestparticle size is 123 nm with conversion 95.8% and monodisperse. The shorter of feeding time the more monomer ofethyl acrylate being polymerized, it is showed by the higher conversion up to 94.4% and the bigger particle size is107.9 nm.

  4. Interactions of Ovalbumin with Ionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    GUO Xia; YAN Hui; GUO Rong

    2008-01-01

    The interactions of ovalbumin (OVA) with one anionic surfactant,sodium dodecyl sulfate (SDS),and two cationic surfactants,dodecyl trimethylammonium bromide (DTAB) and cetyl trimethylammonium bromide (CTAB),in water have been studied through fluorescence and UV-Vis spectroscopies and transmission electronic microscopy,combined with the measurement of conductivity.OVA can increase the critical micelle concentrations (cmc) of SDS and CTAB but has little effect on that of DTAB.The interaction between surfactant monomer and OVA is greater than that between surfactant micelles and OVA.Moreover,SDS can make OVA unfolded while cationic surfactants cannot.

  5. Synthesis of novel quaternary ammonium surfactants containing adamantane

    Institute of Scientific and Technical Information of China (English)

    Jian Wei Guo; Xing Zhong; Hua Zhu; Li Juan Feng; Ying De Cui

    2012-01-01

    A series of novel quaternary ammonium surfactants containing adamantane were designed and synthesized from 1-adamantanecarboxylic acid.The structures of target surfactants were confirmed by 1H NMR,elements analysis and FTIR.Surface properties of these surfactants were investigated.Due to the lipophilicity of adamantane,the critical micelle concentration (CMC) and C20 values of the synthesized quaternary ammonium surfactants are lower than that of conventional quaternary ammonium surfactants.

  6. 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.

  7. Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

    CERN Document Server

    Voisin, D

    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 po...

  8. Anaerobic Biodegradation of Detergent Surfactants

    Directory of Open Access Journals (Sweden)

    Erich Jelen

    2009-03-01

    Full Text Available Detergent surfactantscan be found in wastewater in relevant concentrations. Most of them are known as ready degradable under aerobic conditions, as required by European legislation. Far fewer surfactants have been tested so far for biodegradability under anaerobic conditions. The natural environment is predominantly aerobic, but there are some environmental compartments such as river sediments, sub-surface soil layer and anaerobic sludge digesters of wastewater treatment plants which have strictly anaerobic conditions. This review gives an overview on anaerobic biodegradation processes, the methods for testing anaerobic biodegradability, and the anaerobic biodegradability of different detergent surfactant types (anionic, nonionic, cationic, amphoteric surfactants.

  9. Surfactant-soil interactions during surfactant-amended remediation of contaminated soils by hydrophobic organic compounds: a review.

    Science.gov (United States)

    Laha, Shonali; Tansel, Berrin; Ussawarujikulchai, Achara

    2009-01-01

    Surfactants are amphiphilic molecules that reduce aqueous surface tension and increase the solubility of hydrophobic organic compounds (HOCs). Surfactant-amended remediation of HOC-contaminated soils and aquifers has received significant attention as an effective treatment strategy - similar in concept to using soaps and detergents as washing agents to remove grease from soiled fabrics. The proposed mechanisms involved in surfactant-amended remediation include: lowering of interfacial tension, surfactant solubilization of HOCs, and the phase transfer of HOC from soil-sorbed to pseudo-aqueous phase. However, as with any proposed chemical countermeasures, there is a concern regarding the fate of the added surfactant. This review summarizes the current state of knowledge regarding nonionic micelle-forming surfactant sorption onto soil, and serves as an introduction to research on that topic. Surfactant sorption onto soil appears to increase with increasing surfactant concentration until the onset of micellization. Sorbed-phase surfactant may account for the majority of added surfactant in surfactant-amended remediation applications, and this may result in increased HOC partitioning onto soil until HOC solubilization by micellar phase surfactant successfully competes with increased HOC sorption on surfactant-modified soil. This review provides discussion of equilibrium partitioning theory to account for the distribution of HOCs between soil, aqueous phase, sorbed surfactant, and micellar surfactant phases, as well as recently developed models for surfactant sorption onto soil. HOC partitioning is characterized by apparent soil-water distribution coefficients in the presence of surfactant.

  10. Silicone antifoam performance enhancement by nonionic surfactants in potato medium.

    Science.gov (United States)

    Christiano, Steven P; Fey, Kenneth C

    2003-01-01

    The ability of a silicone antifoam to retard foaming in a liquor prepared from potatoes is enhanced by the addition of ethoxylated nonionic surfactants. The enhancement is non-linear for surfactant concentration, with all 12 surfactants tested possessing a concentration at which foam heights strongly diminish, referred to as the surfactant critical antifoaming concentration (SCAFC). SCAFCs vary between surfactants, with lower values indicating better mass efficiency of antifoaming enhancement. SCAFCs decrease with degree of ethoxylation and decrease with the hydrophilic-lipophilic balance for ethoxylated nonionic surfactants. Surfactant addition produces a mixed water-surface layer containing surfactant and surface-active components in the potato medium. Surface tension reduction does not correlate well with antifoam performance enhancement. A model is proposed where surfactant adsorption promotes desorption of surface-active potato medium components from the water surface. At the SCAFC, desorption is not complete, yet the rate of bubble rupture is sufficiently enhanced to provide excellent foam control.

  11. Investigation of the surfactant type and concentration effect on the retention factors of glutathione and its analogues by micellar electrokinetic chromatography.

    Science.gov (United States)

    Kazarjan, Jana; Mahlapuu, Riina; Hansen, Mats; Soomets, Ursel; Kaljurand, Mihkel; Vaher, Merike

    2015-10-01

    In the present study, a micellar electrokinetic chromatographic method was used to determine the retention factors of hydrophilic monomeric and homodimeric forms of glutathione analogues. Ionic-liquid-based surfactant, 1-tetradecyl-3-methylimidazolium chloride, as well as cetyltrimethylammonium bromide and phosphate buffer (pH 7.4) were employed in the experiments. Since the studied peptides possess a negative charge under physiological conditions, it is expected that the peptides interact with the oppositely charged 1-tetradecyl-3-methylimidazolium chloride and cetyltrimethylammonium bromide micelles via hydrophobically assisted electrostatic forces. The dependence of the retention factor on the micellar concentration of 1-tetradecyl-3-methylimidazolium chloride and cetyltrimethylammonium bromide is nonlinear and the obtained curves converge to a limiting value. The retention factor values of GSH analogues were in the range of 0.36-2.22 for glutathione analogues and -1.21 to 0.37 for glutathione when 1-tetradecyl-3-methylimidazolium chloride was used. When cetyltrimethylammonium bromide was employed, the retention factor values were in the range of 0.27-2.17 for glutathione analogues and -1.22 to 0.06 for glutathione. If sodium dodecyl sulfate was used, the retention factor values of glutathione analogues with carnosine moiety were in the range of -1.54 to 0.38.

  12. Surfactant Adsorption: A Revised Physical Chemistry Lab

    Science.gov (United States)

    Bresler, Marc R.; Hagen, John P.

    2008-01-01

    Many physical chemistry lab courses include an experiment in which students measure surface tension as a function of surfactant concentration. In the traditional experiment, the data are fit to the Gibbs isotherm to determine the molar area for the surfactant, and the critical micelle concentration is used to calculate the Gibbs energy of micelle…

  13. Preparation and Characterization of Polymeric Surfactants Based on Epoxidized Soybean Oil Grafted Hydroxyethyl Cellulose.

    Science.gov (United States)

    Huang, Xujuan; Liu, He; Shang, Shibin; Rao, Xiaoping; Song, Jie

    2015-10-21

    Epoxidized soybean oil (ESO) grafted hydroxyethyl cellulose (HEC) was prepared via ring-opening polymerization, in which the hydroxyl groups of HEC acted as initiators and the polymeric ESO were covalently bonded to the HEC. Hydrolysis of ESO-grafted HEC (ESO-HEC) was performed with sodium hydroxide, and the hydrolyzed ESO-HEC (H-ESO-HEC) products were characterized via Fourier transform infrared (FT-IR) and (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopies, high-temperature gel permeation chromatography (HT-GPC), and differential scanning calorimetry (DSC). The results indicated that ring-opening polymerization of ESO occurred with the hydroxyl groups of HEC as initiators. The molecular weights of the H-ESO-HEC products were varied by adjusting the mass ratio of HEC and ESO. Through neutralizing the carboxylic acid of H-ESO-HEC with sodium hydroxide, novel polymeric surfactants (H-ESO-HEC-Na) were obtained, and the effects of polymeric surfactants on the surface tension of water were investigated as a function of concentration of H-ESO-HEC-Na. The H-ESO-HEC-Na was effective at lowering the surface tension of water to 26.33 mN/m, and the critical micelle concentration (CMC) value decreased from 1.053 to 0.157 g/L with increases in molecular weights of the polymeric surfactants. Rheological measurements indicated that the H-ESO-HEC-Na solutions changed from pseudoplastic property to Newtonian with increasing shear rate.

  14. Surfactant-enhanced cellulose nanocrystal Pickering emulsions.

    Science.gov (United States)

    Hu, Zhen; Ballinger, Sarah; Pelton, Robert; Cranston, Emily D

    2015-02-01

    The effect of surfactants on the properties of Pickering emulsions stabilized by cellulose nanocrystals (CNCs) was investigated. Electrophoretic mobility, interfacial tension, confocal microscopy and three-phase contact angle measurements were used to elucidate the interactions between anionic CNCs and cationic alkyl ammonium surfactants didecyldimethylammonium bromide (DMAB) and cetyltrimethylammonium bromide (CTAB). Both surfactants were found to adsorb onto CNCs with concentration-dependent morphology. At low concentrations, individual surfactant molecules adsorbed with alkyl tails pointing outward leading to hydrophobic CNCs. At higher concentrations, above the surfactant's apparent critical micelle concentration, surfactant aggregate morphologies on CNCs were inferred and the hydrophobicity of CNCs decreased. DMAB, which has two alkyl tails, rendered the CNCs more hydrophobic than CTAB which has only a single alkyl tail, at all surfactant concentrations. The change in CNC wettability from surfactant adsorption was directly linked to emulsion properties; adding surfactant increased the emulsion stability, decreased the droplet size, and controlled the internal phase of CNC Pickering emulsions. More specifically, a double transitional phase inversion, from oil-in-water to water-in-oil and back to oil-in-water, was observed for emulsions with CNCs and increasing amounts of DMAB (the more hydrophobic surfactant). With CNCs and CTAB, no phase inversion was induced. This work represents the first report of CNC Pickering emulsions with surfactants as well as the first CNC Pickering emulsions that can be phase inverted. The ability to surface modify CNCs in situ and tailor emulsions by adding surfactants may extend the potential of CNCs to new liquid formulations and extruded/spray-dried materials.

  15. Using biologically soft surfactants for dust suppression

    Energy Technology Data Exchange (ETDEWEB)

    Tkachenko, N.G.; Kolodiichak, V.K.; Motrii, A.E.; Severin, V.D.

    1982-07-01

    This article discusses environmental aspects of using surfactants in coal mines for dust suppression. Surfactants for underground black coal mines in the USSR are divided into three classes: so-called soft surfactants with a decomposition period from 1 to 3 days, hard surfactants with decomposition exceeding a month and an intermediary group. The decomposition process is analyzed; the role played by fermentation is stressed. Environmental effects of surfactant decomposition are evaluated. Selected surfactants tested in Soviet laboratories are described. The results of experimental use of diethanolamide as a surfactant for water injection in coal seams are evaluated. Wetting time amounts to 1 s when a 0.2% concentration is used. When surfactant concentration in water is reduced to 0.05% wetting time does not change; when concentration decreases to 0.025% wetting time increases to 3 s. Surfactant efficiency is investigated under operational conditions in a Donbass mine. Specifications of the working face, mining system and air pollution caused by a shearer loader are discussed. When diethanolamide is used dust suppression efficiency ranges from 86.4 to 90.4%. During the tests diethanolamide concentration in water was 0.05%.

  16. Electrokinetic investigation of surfactant adsorption.

    Science.gov (United States)

    Bellmann, C; Synytska, A; Caspari, A; Drechsler, A; Grundke, K

    2007-05-15

    Fuerstenau [D.W. Fuerstenau, in: M.L. Hair (Ed.), Dekker, New York, 1971, p. 143] has already discussed the role of hydrocarbon chain of surfactants, the effect of alkyl chain length, chain structure and the pH of the solution on the adsorption process of surfactants. Later Kosmulski [M. Kosmulski, Chemical Properties of Material Surfaces, Surfactant Science Series, vol. 102, Dekker, New York, Basel, 2001] included the effect of surfactant concentration, equilibration time, temperature and electrolyte in his approaches. Certainly, the character of the head groups of the surfactant and the properties of the adsorbent surface are the basis for the adsorption process. Different surfactants and adsorbents cause different adsorption mechanisms described firstly by Rosen [M.J. Rosen, Surfactants and Interfacial Phenomena, second ed., Wiley, New York, 1989]. These adsorption mechanisms and their influencing factors were studied by electrokinetic investigations. Here only changes of the charges at the surfaces could be detected. To control the results of electrokinetic investigations they were compared with results from ellipsometric measurements. In the case of surfactant adsorption the chain length was vitally important. It could be shown by the adsorption of alkyl trimethyl ammonium bromides onto polymer films spin coated at wafer surfaces. The influence of the chain length depending on surface properties of the polymer film was studied. Streaming potential measurements were applied for these investigations. The obtained results enabled us to calculate the molar cohesive free energy per mol of CH2-group in the alkaline chain of the surfactant if all other specific adsorption effects were neglected.

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

    Science.gov (United States)

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

    2014-09-17

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

  18. 更加完美索尼DSC-TX9C/DSC-WX5C魅力出击

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    DSC-TX9C和DSC-WX5C分别为一代经典大热机型DSC-TXTC和DSC—WX1的后继产品。延续Exmor RCMOS影像传感器所带来的强大功能,在设计细节和功能应用上均有大幅提升。

  19. 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.

  20. DSC and universal bit-level combining for HARQ systems

    Directory of Open Access Journals (Sweden)

    Lv Tiejun

    2011-01-01

    Full Text Available Abstract This paper proposes a Dempster -Shafer theory based combining scheme for single-input single-output (SISO systems with hybrid automatic retransmission request (HARQ, referred to as DSC, in which two methods for soft information calculations are developed for equiprobable (EP and non-equiprobable (NEP sources, respectively. One is based on the distance from the received signal to the decision candidate set consisting of adjacent constellation points when the source bits are equiprobable, and the corresponding DSC is regarded as DSC-D. The other is based on the posterior probability of the transmitted signals when the priori probability for the NEP source bits is available, and the corresponding DSC is regarded as DSC-APP. For the diverse EP and NEP source cases, both DSCD and DSC-APP are superior to maximal ratio combining, the so-called optimal combining scheme for SISO systems. Moreover, the robustness of the proposed DSC is illustrated by the simulations performed in Rayleigh channel and AWGN channel, respectively. The results show that the proposed DSC is insensitive to and especially applicable to the fading channels. In addition, a DS detection-aided bit-level DS combining scheme is proposed for multiple-input multiple-output--HARQ systems. The bit-level DS combining is deduced to be a universal scheme, and the traditional log-likelihood-ratio combining is a special case when the likelihood probability is used as bit-level soft information.

  1. Development of a sublation system in atmospheric tank using sunflower oil surfactant to reduce oily water concentration; Desenvolvimento de um sistema de sublacao em tanque atmosferico utilizando tensoativo de oleo de girassol para reducao da concentracao de aguas oleosas

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Rodrigo F. de; Dantas, Iuri A.C.; Quintaes, Filipe de O.; Salazar, Andres O.; Barros Neto, Eduardo L. de [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2008-07-01

    In order to reduce the rate of oil in water, was developed a system capable to be inserted in a tank and make air bubbles move to top of the tank, where is a layer of oil, similar that occurs in flotation, but in this case is called sublation. This system is composed by drilled PVC pipes and connected in way of four identical squares, joined by a high pressure hose. A compressor located in a region near to the tank supplies air to the system through the hose, that is connected in the central point of the system. The preliminary results had shown that the concentration after the sublation, without the surfactants use, decrease of 70 ppm to 35 ppm. After the sublation using surfactants this concentration decrease of 70ppm to 24,8 ppm. The efficiency of the sublation process using surfactants made of vegetal oil - OGS - was proved by the experimental results. This process, beyond allowing a bigger reutilization of the water in the tests of the laboratory, makes possible the reduction of the rate of oil in water to permitted levels by CONAMA. (author)

  2. Development of a sublation system in atmospheric tank using sunflower oil surfactant to reduce oily water concentration; Desenvolvimento de um sistema de sublacao em tanque atmosferico utilizando tensoativo de oleo de girassol para reducao da concentracao de aguas oleosas

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Rodrigo F. de; Dantas, Iuri A.C.; Quintaes, Filipe de O.; Salazar, Andres O.; Barros Neto, Eduardo L. de [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2008-07-01

    In order to reduce the rate of oil in water, was developed a system capable to be inserted in a tank and make air bubbles move to top of the tank, where is a layer of oil, similar that occurs in flotation, but in this case is called sublation. This system is composed by drilled PVC pipes and connected in way of four identical squares, joined by a high pressure hose. A compressor located in a region near to the tank supplies air to the system through the hose, that is connected in the central point of the system. The preliminary results had shown that the concentration after the sublation, without the surfactants use, decrease of 70 ppm to 35 ppm. After the sublation using surfactants this concentration decrease of 70ppm to 24,8 ppm. The efficiency of the sublation process using surfactants made of vegetal oil - OGS - was proved by the experimental results. This process, beyond allowing a bigger reutilization of the water in the tests of the laboratory, makes possible the reduction of the rate of oil in water to permitted levels by CONAMA. (author)

  3. 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.

  4. A Review on Progress in QSPR Studies for Surfactants

    Directory of Open Access Journals (Sweden)

    Zhengwu Wang

    2010-03-01

    Full Text Available This paper presents a review on recent progress in quantitative structure-property relationship (QSPR studies of surfactants and applications of various molecular descriptors. QSPR studies on critical micelle concentration (cmc and surface tension (γ of surfactants are introduced. Studies on charge distribution in ionic surfactants by quantum chemical calculations and its effects on the structures and properties of the colloids of surfactants are also reviewed. The trends of QSPR studies on cloud point (for nonionic surfactants, biodegradation potential and some other properties of surfactants are evaluated .

  5. Freely dissolved concentrations of anionic surfactants in seawater solutions: optimization of the non-depletive solid-phase microextraction method and application to linear alkylbenzene sulfonates.

    NARCIS (Netherlands)

    Rico Rico, A.; Droge, S.T.J.; Widmer, D.; Hermens, J.L.M.

    2009-01-01

    A solid-phase microextraction method (SPME) has been optimized for the analysis of freely dissolved anionic surfactants, namely linear alkylbenzene sulfonates (LAS), in seawater. An effect of the thermal conditioning treatment on the polyacrylate fiber coating was demonstrated for both uptake kineti

  6. MICROBIAL SURFACTANTS. II. LIPOPEPTIDES

    Directory of Open Access Journals (Sweden)

    T. P. Pirog

    2014-04-01

    Full Text Available The classification and the chemical structure of the lipopeptides and their producers (bacteria of the genera Bacillus and Pseudomonas are given. The role of the lipopeptides in cells motility, biofilm formation, metal binding and xenobiotics degradation and their action on the cells of pro- and eukaryotes is summarized. The stages of the nonribosomal lipopeptides synthesis and the role of two-component (GacA/GacS, ComA/ComP and the quorum system regulation of this process are shown. The potential of lactic acid bacteria and marine microorganisms as alternative surfactants producers (glycolipids, lipopeptides, phospholipids and fatty acids, glycolipopeptides are discussed. Their productivity and advantages over traditional producers are given as well. The properties of surfactants synthesized by lactic acid bacteria (the reduction of the surface tension, the critical micelle concentration, the stability in a wide range of pH, the temperature, the biological activity are summarized. Surfactants of nonpathogenic probiotic bacteria could be used as effective antimicrobial agents and antiadhesive and marine producers which able to synthesize unique metabolites that are not produced by other microorganisms.

  7. Interaction of Fluorocarbon Containing Hydrophobically Modified Polyelectrolyte with Nonionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    GUO,Jin-Feng(郭金峰); ZHUANG,Dong-Qing(庄东青); ZHOU,Hui(周晖); ZHANG,Yun-Xiang(章云祥)

    2002-01-01

    The interaction of fluorocarbon containing hydrophobically modified polyelectrolyte (FMPAANa) with two kinds of nonionic surfactants (hydrogenated and fluorinated) in a semidilute (0.5 wt% ) aqueous solution had been studied by rheological measurements. Association behavior was found in both systems. The hydrophobic interaction of FMPAANa with fluorinated surfactant (FC171) is much stronger than that with hydrogenated surfactant (NP7.5) at low surfactant concentrations. The interaction is strengthened by surfactants being added for the density of active junctions increased. Whereas distinct phenomena for FC171 and NP7. 5 start to be found as the surfactants added over their respective certain concentration. The interaction of polyelectrolyte with fluorinated surfactant increases dramatical ly while that with hydrogenated surfactant decreases.

  8. Interactions of organic contaminants with mineral-adsorbed surfactants

    Science.gov (United States)

    Zhu, L.; Chen, B.; Tao, S.; Chiou, C.T.

    2003-01-01

    Sorption of organic contaminants (phenol, p-nitrophenol, and naphthalene) to natural solids (soils and bentonite) with and without myristylpyridinium bromide (MPB) cationic surfactant was studied to provide novel insight to interactions of contaminants with the mineral-adsorbed surfactant. Contaminant sorption coefficients with mineral-adsorbed surfactants, Kss, show a strong dependence on surfactant loading in the solid. At low surfactant levels, the Kss values increased with increasing sorbed surfactant mass, reached a maximum, and then decreased with increasing surfactant loading. The Kss values for contaminants were always higher than respective partition coefficients with surfactant micelles (Kmc) and natural organic matter (Koc). At examined MPB concentrations in water the three organic contaminants showed little solubility enhancement by MPB. At low sorbed-surfactant levels, the resulting mineral-adsorbed surfactant via the cation-exchange process appears to form a thin organic film, which effectively "adsorbs" the contaminants, resulting in very high Kss values. At high surfactant levels, the sorbed surfactant on minerals appears to form a bulklike medium that behaves essentially as a partition phase (rather than an adsorptive surface), with the resulting Kss being significantly decreased and less dependent on the MPB loading. The results provide a reference to the use of surfactants for remediation of contaminated soils/sediments or groundwater in engineered surfactant-enhanced washing.

  9. 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 (C4E1, C8E3 and C12E5) 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.

  10. A Review on Progress in QSPR Studies for Surfactants

    OpenAIRE

    Zhengwu Wang; Xiaoyi Zhang; Jiwei Hu

    2010-01-01

    This paper presents a review on recent progress in quantitative structure-property relationship (QSPR) studies of surfactants and applications of various molecular descriptors. QSPR studies on critical micelle concentration (cmc) and surface tension (γ) of surfactants are introduced. Studies on charge distribution in ionic surfactants by quantum chemical calculations and its effects on the structures and properties of the colloids of surfactants are also reviewed. The trends of QSPR studies o...

  11. 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.

  12. Differential Scanning Calorimetry (DSC) for planetary surface exploration

    Science.gov (United States)

    Gooding, James L.; Ming, Douglas W.

    1993-01-01

    Differential Scanning Calorimetry (DSC) is the quantitative measurement of the enthalpic response of a material to a systematic change in temperature. In practice, the heat flow into or outward from a sample is measured as the sample is heated or cooled at a carefully controlled rate. DSC superficially resembles, but is not the same as differential thermal analysis (DTA), which is the measurement of temperature differences between a sample and reference material as the pair is heated or cooled. The fundamental properties measured by DSC are enthalpies and temperatures of phase transitions and constant-pressure heat capacities. Depending on instrument design and the nature of the sample, high-quality DSC analyses can be obtained on only a few milligrams of solid materials. DSC requires direct contact with the sample and generally degrades, if not destroys, the sample as a consequence of heating. In laboratory applications, it is common to subject the gaseous effluent from the DSC to analysis by a separate evolved-gas analyzer (EGA).

  13. EXPERIMENTAL CHARACTERIZATION OF FLUOROCARBON-MODIFIED POLYACRYLAMIDE/SURFACTANT AQUEOUS SOLUTIONS

    Institute of Scientific and Technical Information of China (English)

    Huai-tian Bu; Zhen-zhong Yang; Yun-xiang Zhang

    2003-01-01

    The interaction between surfactants and fluorocarbon-modified polyacrylamide (FC-PAM) in aqueous solutions was evaluated by theological means and fluorescence spectroscopy and was found to be strong regardless of the surfactant's nature. Two representative surfactants, anionic sodium dodecyl sulfate (SDS) and nonionic Triton X-100, were used. The origin of the interaction and its dependence on the surfactant concentration were discussed.

  14. Thermally cleavable surfactants

    Science.gov (United States)

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

    2006-04-04

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

  15. Thermally cleavable surfactants

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-09-29

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

  16. Thermally cleavable surfactants

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-11-24

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

  17. Low-temperature phase behavior of fatty acid methyl esters by differential scanning calorimetry (DSC)

    Science.gov (United States)

    Fatty acid methyl ester (FAME) mixtures have many uses including biodiesel, lubricants, metal-working fluids, surfactants, polymers, coatings, green solvents and phase-change materials. The physical properties of a FAME mixture depends on the fatty acid concentration (FAC) profile. Some products hav...

  18. Hemolysis by surfactants--A review.

    Science.gov (United States)

    Manaargadoo-Catin, Magalie; Ali-Cherif, Anaïs; Pougnas, Jean-Luc; Perrin, Catherine

    2016-02-01

    An overview of the use of surfactants for erythrocyte lysis and their cell membrane action mechanisms is given. Erythrocyte membrane characteristics and its association with the cell cytoskeleton are presented in order to complete understanding of the erythrocyte membrane distortion. Cell homeostasis disturbances caused by surfactants might induce changes starting from shape modification to cell lysis. Two main mechanisms are hypothesized in literature which are osmotic lysis and lysis by solubilization even if the boundary between them is not clearly defined. Another specific mechanism based on the formation of membrane pores is suggested in the particular case of saponins. The lytic potency of a surfactant is related to its affinity for the membrane and the modification of the lipid membrane curvature. This is to be related to the surfactant shape defined by its hydrophobic and hydrophilic moieties but also by experimental conditions. As a consequence, prediction of the hemolytic potency of a given surfactant is challenging. Several studies are focused on the relation between surfactant erythrolytic potency and their physico-chemical parameters such as the critical micellar concentration (CMC), the hydrophile-lipophile balance (HLB), the surfactant membrane/water partition coefficient (K) or the packing parameter (P). The CMC is one of the most important factors considered even if a lytic activity cut-off effect points out that the only consideration of CMC not enough predictive. The relation K.CMC must be considered in addition to the CMC to predict the surfactant lytic capacity within the same family of non ionic surfactant. Those surfactant structure/lytic activity studies demonstrate the requirement to take into account a combination of physico-chemical parameters to understand and foresee surfactant lytic potency.

  19. DSC “peak temperature” versus “maximum slope temperature” in determining TSSD temperature

    Science.gov (United States)

    Khatamian, D.

    2010-10-01

    One of the concerns of the nuclear industry is the deleterious effect of hydrogen on the structural integrity of the reactor core components due to delayed hydride cracking (DHC). The DHC process occurs when hydrogen concentration exceeds the terminal solid solubility (TSS) in the component. Thus, the accurate knowledge of TSS is necessary to predict the lifetime of the components. Differential scanning calorimetry (DSC) is normally used to measure the hydrogen TSS in zirconium alloys. There is a measurable change in the amount of heat absorbed by the specimen when the hydrides dissolve. The hydride dissolution process does not exhibit a well-defined "sharp" change in the heat-flow signal at the transition temperature. A typical DSC heat-flow curve for hydride dissolution has three definite features; "peak temperature" (PT), "maximum slope temperature" (MST) and "completion temperature". The present investigation aims to identify the part of the heat-flow signal that closely corresponds to the TSS temperature for hydride dissolution ( TTSSD). Coupons were cut from a Zr-2.5Nb specimen, which had been previously hydrided using an electrolytic cell to create a surface hydride layer of ˜20 μm thick on all sides of the specimen. The coupons were then annealed isothermally at various temperatures to establish the TTSSD under equilibrium conditions. Subsequently the hydride layer was removed and the coupons were analyzed for TSSD temperature using DSC. The PT and MST for each DSC run were determined and compared to the annealing temperature of the coupon. The results show that the annealing temperature (the equilibrium TTSSD) is much closer to the DSC PT than any other feature of the heat-flow curve.

  20. A disjoining pressure model with effect of surfactant concentration in spreading of liquid drops%液滴铺展过程中受活性剂浓度影响的分离压模型研究

    Institute of Scientific and Technical Information of China (English)

    王松岭; 李春曦; 叶学民

    2011-01-01

    结合已有的实验结果,通过考虑活性剂特性和浓度对分子间引力和斥力的不同影响,建立了通用的分离压理论模型,并给出了自由能密度表达式.所建模型包含了活性剂浓度Γ、毛细力数C、指数(m,n),以及预置液膜厚度h∞等因素的影响,进一步完善了分离压模型的理论研究.%Combining with published experimental results, a general disjoining pressure model is established based on considering the different influence of surfactant concentration on intermolecular repulsive and attractive forces, and the expression of the free energy density is formulated in present paper. The present model includes the effects of surfactant concentration г, capillary number C, exponents index ( m, n) and prewetted film thickness h∞, and provides an improved theoretical model for exploring the disjoining pressure.

  1. Aggregation of sulfosuccinate surfactants in water

    Energy Technology Data Exchange (ETDEWEB)

    Magid, L.J.; Daus, K.A.; Butler, P.D.; Quincy, R.B.

    1983-12-22

    The aggregation of sodium di-n-alkyl sulfosuccinates in water (H/sub 2/O and D/sub 2/O at 45/sup 0/C) has been investigated. A self-consistent picture of the dependence of sodium ion binding on surfactant concentration is obtained from emf measurements, conductimetry, and small-angle neutron scattering (SANS) measurements. The concentration dependence of the micellar agregation number for the sulfosuccinates and related double-tailed surfactants depends markedly on surfactant solubility. A sphere-to-disk transition in micellar shape, which might have been expected as a precursor to formation of a lamellar mesophase, was not observed as the surfactant concentration was increased. 8 figures, 2 tables.

  2. Effect of surfactant concentration and interfacial slip on the flow past a viscous drop at low surface P\\'eclet number

    CERN Document Server

    Sekhar, G P Raja; Rohde, Christian

    2016-01-01

    The motion of a viscous drop is investigated when the interface is fully covered with a stagnant layer of surfactant in an arbitrary unsteady Stokes flow for the low surface P\\'eclet number limit. The effect of the interfacial slip coefficient on the behavior of the flow field is also considered. The hydrodynamic problem is solved by the solenoidal decomposition method and the drag force is computed in terms of Faxen's laws using a perturbation ansatz in powers of the surface P\\'eclet number. The analytical expressions for the migration velocity of the drop are also obtained in powers of the surface P\\'eclet number. Further instances corresponding to a given ambient flow as uniform flow, Couette flow, Poiseuille flow are analyzed. Moreover, it is observed that, a surfactant-induced cross-stream migration of the drop occur towards the centre-line in both Couette flow and Poiseuille flow cases. The variation of the drag force and migration velocity is computed for different parameters such as P\\'eclet number, M...

  3. Effect of milling on DSC thermogram of excipient adipic acid.

    Science.gov (United States)

    Ng, Wai Kiong; Kwek, Jin Wang; Yuen, Aaron; Tan, Chin Lee; Tan, Reginald

    2010-03-01

    The purpose of this research was to investigate why and how mechanical milling results in an unexpected shift in differential scanning calorimetry (DSC) measured fusion enthalpy (Delta(fus)H) and melting point (T(m)) of adipic acid, a pharmaceutical excipient. Hyper differential scanning calorimetry (hyper-DSC) was used to characterize adipic acid before and after ball-milling. An experimental study was conducted to evaluate previous postulations such as electrostatic charging using the Faraday cage method, crystallinity loss using powder X-ray diffraction (PXRD), thermal annealing using DSC, impurities removal using thermal gravimetric analysis (TGA) and Karl Fischer titration. DSC thermograms showed that after milling, the values of Delta(fus)H and T(m) were increased by approximately 9% and 5 K, respectively. Previous suggestions of increased electrostatic attraction, change in particle size distribution, and thermal annealing during measurements did not explain the differences. Instead, theoretical analysis and experimental findings suggested that the residual solvent (water) plays a key role. Water entrapped as inclusions inside adipic acid during solution crystallization was partially evaporated by localized heating at the cleaved surfaces during milling. The correlation between the removal of water and melting properties measured was shown via drying and crystallization experiments. These findings show that milling can reduce residual solvent content and causes a shift in DSC results.

  4. 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.

  5. Dimeric Surfactants: Promising Ingredients of Cosmetics and Toiletries

    Directory of Open Access Journals (Sweden)

    Naveen Kumar

    2013-11-01

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

  6. Rheological properties of ovalbumin hydrogels as affected by surfactants addition.

    Science.gov (United States)

    Hassan, Natalia; Messina, Paula V; Dodero, Veronica I; Ruso, Juan M

    2011-04-01

    The gel properties of ovalbumin mixtures with three different surfactants (sodium perfluorooctanoate, sodium octanoate and sodium dodecanoate) have been studied by rheological techniques. The gel elasticities were determined as a function of surfactant concentration and surfactant type. The fractal dimension of the formed structures was evaluated from plots of storage modulus against surfactant concentration. The role of electrostatic, hydrophobic and disulfide SS interactions in these systems has been demonstrated to be the predominant. The viscosity of these structures tends to increase with surfactant concentration, except for the fluorinated one. Unfolded ovalbumin molecules tend to form fibrillar structures that tend to increase with surfactant concentration, except for the fluorinated one. This fact has been related to the particular nature of this molecule.

  7. Physical properties of botanical surfactants.

    Science.gov (United States)

    Müller, Lillian Espíndola; Schiedeck, Gustavo

    2017-08-24

    Some vegetal species have saponins in their composition with great potential to be used as natural surfactants in organic crops. This work aims to evaluate some surfactants physical properties of Quillaja brasiliensis and Agave angustifolia, based on different methods of preparation and concentration. The vegetal samples were prepared by drying and grinding, frozen and after chopped or used fresh and chopped. The neutral bar soap was used as a positive control. The drying and grinding of samples were the preparation method that resulted in higher foam column height in both species but Q. brasiliensis was superior to A. angustifolia in all comparisons and foam index was 2756 and 1017 respectively. Critical micelle concentration of Q. brasiliensis was 0.39% with the superficial tension of 54.40mNm(-1) while neutral bar soap was 0.15% with 34.96mNm(-1). Aspects such as genetic characteristics of the species, environmental conditions, and analytical methods make it difficult to compare the results with other studies, but Q. brasiliensis powder has potential to be explored as a natural surfactant in organic farming. Not only the surfactants physical properties of botanical saponins should be taken into account but also its effect on insects and diseases control when decided using them. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Modeling of surfactant transport and adsorption in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Chung, F.T.H.

    1991-04-01

    When surfactant solution is flowing in a reservoir formation, surfactants will be diluted by flow dispersion, retained in dead-end pores, adsorbed on rock surfaces, or precipitated due to ion exchange. The loss of surfactant will be detrimental to the performance of gas foam. Information of surfactant concentration profiles in reservoir formations is essential for gas foaming technique development. The major objective of this research is to investigate with mathematical models the transport and dynamic adsorption of surfactants in porous media. The mathematical models have taken into account the convection, dispersion, capacitance, and adsorption effects on concentrations of surfactants. Numerical methods and computer programs have been developed which can be used to match experimental results and to determine the characterization parameters in the models. The models can be included in foam simulation programs to calculate surfactant concentration profiles in porous media. A flow experimental method was developed to measure the effluent surfactant concentration, which will be used to determine the model parameters. Commercial foaming agent Alipal CD-128 was used in this study. Equilibrium adsorption and surfactant precipitation have been tested. Tracer solutions with a nonadsorbing solute such as dextrose and sucrose were used to determine the dispersion parameters for the experimental sandpack; thus, the adsorption of the surfactant in the test sand can be identified with an adequate model. 49 refs., 21 figs.

  9. Fluorescence emission of pyrene in surfactant solutions.

    Science.gov (United States)

    Piñeiro, Lucas; Novo, Mercedes; Al-Soufi, Wajih

    2015-01-01

    The systematic description of the complex photophysical behaviour of pyrene in surfactant solutions in combination with a quantitative model for the surfactant concentrations reproduces with high accuracy the steady-state and the time resolved fluorescence intensity of pyrene in surfactant solutions near the cmc, both in the monomer and in the excimer emission bands. We present concise model equations that can be used for the analysis of the pyrene fluorescence intensity in order to estimate fundamental parameters of the pyrene-surfactant system, such as the binding equilibrium constant K of pyrene to a given surfactant micelle, the rate constant of excimer formation in micelles, and the equilibrium constant of pyrene-surfactant quenching. The values of the binding equilibrium constant K(TX100)=3300·10³ M⁻¹ and K(SDS)=190·10³ M⁻¹ for Triton X-100 (TX100) and SDS micelles, respectively, show that the partition of pyrene between bulk water and micelles cannot be ignored, even at relatively high surfactant concentrations above the cmc. We apply the model to the determination of the cmc from the pyrene fluorescence intensity, especially from the intensity ratio at two vibronic bands in the monomer emission or from the ratio of excimer to monomer emission intensity. We relate the finite width of the transition region below and above the cmc with the observed changes in the pyrene fluorescence in this region.

  10. An Investigation of CNT Cytotoxicity by Using Surfactants in Different Ratio

    Science.gov (United States)

    Kumar, Sandeep; Kumar, Neeraj; Thakur, Rajesh; Bhanjana, Gaurav; Dilbaghi, Neeraj

    2011-12-01

    This account reports a comparative analysis on dispersion of multiwalled and single walled carbon nanotubes with different surfactants like—Triton X-100, Tween 20, Tween 80, and sodium dodecyl sulfate (SDS). Dispersion of CNTs has been characterized by UV-Vis spectroscopy, electron microscopy and probe microscopy. An optimum CNT-to-surfactant ratio has been determined for each surfactant. Surfactant concentration in different ratio is found to deteriorate the quality of nanotube dispersion. Electron microscopy analysis of a high-surfactant sample concentration enables us to construct a plausible mechanism for increase or decrease in CNT dispersion at high surfactant concentration.

  11. DSC study of martensite transformation in TiPt alloys

    CSIR Research Space (South Africa)

    Chikosha, S

    2012-09-01

    Full Text Available .J. Witcomb, L.A. Cornish, Metall. & Mat. Trans. A , 2001, 32A:1881-86 K. Otsuka & X Ren, Prog. Mat. Scie., 2005, 50:511-75 Page 6 Experimental Procedure ? CSIR 2012 www.csir.co.za Ti-50at%Pt BE powder Hot Press SPS Cold...-Press & Sinter SEM/EDS & DSC Page 7 Spark Plasma Sintering 1200?C, 60 MPa ? Incomplete homogenisation of the bulk ? Pt-rich TiPt phase is formed, coexisting with other phases ? DSC shows two overlapping peaks instead of one, possible two-stage Ti...

  12. DSC Study on the Polyacrylonitrile Precursors for Carbon Fibers

    Institute of Scientific and Technical Information of China (English)

    Wangxi ZHANG; Musen LI

    2005-01-01

    Different polyacrylonitrile (PAN) precursor fibers that displayed various thermal properties were studied by using differential scanning calorimetry (DSC). Results showed that some commercial PAN precursor fibers displayed double separated peaks and these fibers were of high quality because of their process stability during their conversion to carbon fibers of high performance. Some fabrication processes, such as spinning, drawing, could not apparently change the DSC features of a PAN precursor fiber. It was concluded that the thermal properties of a PAN precursor fiber was mainly determined from its comonomer content type and compositions.

  13. Quantitative Structure-Property Relationship of the Critical Micelle Concentration of Different Classes of Surfactants%多种类表面活性剂临界胶束浓度定量构效关系

    Institute of Scientific and Technical Information of China (English)

    朱志臣; 王强; 贾青竹; 汤红梅; 马沛生

    2013-01-01

      表面活性剂的临界胶束浓度(CMC)是个非常重要的物质特性参数, CMC在研究表面活性剂的工业应用和生物利用方面发挥着关键作用.本工作提出了一个新的拓扑指数—扩展距离矩阵,建立了一个稳定的构效关系模型,并对175种表面活性剂的临界胶束浓度进行了计算预测.结果表明,基于新的拓扑指数建立的构效关系模型计算临界胶束浓度能给出稳定可靠的预测结果,其预测结果相关性系数R2(training set)=0.9295,平均相对偏差ARD(training set)=8.20%, R2(testing set)=0.9257, ARD(testing set)=6.76%.与文献中模型预测结果的对比表明,本工作在稳定性和可靠性上均有显著改善.%Critical micel e concentration (CMC) is one of the most useful parameters for the characterization of surfactants; thus, CMC plays an important role in the investigation of the surfactantsʹproperties for industrial applications and biological utilizations. The fol owing study presents a stable and accurate structure-property relationship model for the prediction of CMC for a diverse set of 175 surfactants using a new topological index, the extended distance matrix. Research indicates that the new model based on this topological index is very efficient and provides satisfactory results. The high-quality prediction model is evidenced by an R2 (square correlation coefficient) value of 0.9295 and an average relative difference (ARD) value of 8.20% for the training set, an R2 value of 0.9257 and an ARD value of 6.76% for the testing set. Comparison results with reference models demonstrate that this new method based on the topological index results in significant improvements, both in accuracy and stability for predicting CMC of surfactants.

  14. Effect of surfactant concentration in the electrolyte on the tribological properties of nickel-tungsten carbide composite coatings produced by pulse electro co-deposition

    Science.gov (United States)

    Kartal, Muhammet; Uysal, Mehmet; Gul, Harun; Alp, Ahmet; Akbulut, Hatem

    2015-11-01

    A nickel plating bath containing WC particles was used to obtain hard and wear-resistant particle reinforced Ni/WC MMCs on steel surfaces for anti-wear applications. Copper substrates were used for electro co-deposition of Ni matrix/WC with the particle size of nickel films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of the surfactant on the zeta potential, co-deposition and distribution of WC particles in the nickel matrix, as well as the tribological properties of composite coatings were also investigated. The tribological behaviors of the electrodeposited WC composite coatings sliding against M50 steel ball (Ø 10 mm) were examined on a CSM Instrument. All friction and wear tests were performed without lubrication at room temperature and in the ambient air (relative humidity 55-65%).

  15. Effect of gamma irradiation on thermophysical properties of plasticized starch and starch surfactant films

    Science.gov (United States)

    Cieśla, Krystyna; Watzeels, Nick; Rahier, Hubert

    2014-06-01

    In this work the influence of gamma irradiation on the thermomechanical properties of the films formed in potato starch-glycerol and potato starch-glycerol-surfactant systems were examined by Dynamic Mechanical Analysis, DMA, and Differential Scanning Calorimetry, DSC, and the results were correlated to the amount of the volatile fraction in the films.

  16. Molecular-thermodynamic theory of micellization of multicomponent surfactant mixtures: 2. pH-sensitive surfactants.

    Science.gov (United States)

    Goldsipe, Arthur; Blankschtein, Daniel

    2007-05-22

    In article 1 of this series, we developed a molecular-thermodynamic (MT) theory to model the micellization of mixtures containing an arbitrary number of conventional (pH-insensitive) surfactants. In this article, we extend the MT theory to model mixtures containing a pH-sensitive surfactant. The MT theory was validated by examining mixtures containing both a pH-sensitive surfactant and a conventional surfactant, which effectively behave like ternary surfactant mixtures. We first compared the predicted micellar titration data to experimental micellar titration data that we obtained for varying compositions of mixed micelles containing the pH-sensitive surfactant dodecyldimethylamine oxide (C12DAO) mixed with either a cationic surfactant (dodecyltrimethylammonium bromide, C12TAB), a nonionic surfactant (dodecyl octa(ethylene oxide), C12E8), or an anionic surfactant (sodium dodecyl sulfate, SDS) surfactant. The MT theory accurately modeled the titration behavior of C12DAO mixed with C12E8. However, C12DAO was observed to interact more favorably with SDS and with C12TAB than was predicted by the MT theory. We also compared predictions to data from the literature for mixtures of C12DAO and SDS. Although the pH values of solutions with no added acid were modeled with only qualitative accuracy, the MT theory resulted in quantitatively accurate predictions of solution pH for mixtures containing added acid. In addition, the predicted degree of counterion binding yielded a lower bound to the experimentally measured value. Finally, we predicted the critical micelle concentration (cmc) of solutions of two pH-sensitive surfactants, tetradecyldimethylamine oxide (C14DAO) and hexadecyldimethyl betaine (C16Bet), at varying solution pH and surfactant composition. However, at the pH values considered, the pH sensitivity of C16Bet could be neglected, and it was equivalently modeled as a zwitterionic surfactant. The cmc's predicted using the MT theory agreed well with the experimental

  17. A novel cloud point extraction approach using cationic surfactant for the separation and pre-concentration of chromium species in natural water prior to ICP-DRC-MS determination.

    Science.gov (United States)

    Meeravali, Noorbasha N; Jiang, Shiuh-Jen

    2009-11-15

    A novel cloud point phase separation of cationic surfactant, Aliquat-336 and capabilities of its reactive solubilizing sites for selective extraction of chromium species at ultra trace levels was examined in natural water. The phase separation behavior of Aliquat-336 is studied with various additives. The nonionic surfactant, Triton X-114 was found to induce the cloud point phase separation of Aliquat-336. The separation of anionic Cr(VI) was enabled by the formation of ion associate with quaternary ammonium head group of Aliquat-336 at pH 2, and the recovery of Cr(VI) and Cr(III) were 101.4+/-1.4% and 2.2+/-0.4%, respectively at 0.5-1 ng mL(-1), Total Cr was pre-concentrated as Cr-APDC species using the hydrophobic tail group at pH 6.5. The Cr(III) concentration was obtained by subtracting Cr(VI) from total Cr. The recovery of total Cr was 99.5+/-1.2%. Parameters affecting extraction were assessed. The procedure was applied to NIST 1643c and NIST 1643d waters, and the sum of individual species obtained was compared with the certified chromium values. The method was also applied to various natural waters with limits of detection and pre-concentration factor of 0.010 and 0.025 ng mL(-1); 10 and 10, respectively, for Cr(VI) and Cr(III)-APDC using ICP-MS operated in DRC mode.

  18. Foaming behaviour of polymer-surfactant solutions

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes-MartInez, Alfredo [Departamento de Investigacion en PolImeros y Materiales, Universidad de Sonora, Apartado Postal 130, 83000 Hermosillo, Sonora (Mexico); Maldonado, Amir [Departamento de Fisica, Universidad de Sonora, Apartado Postal 1626, 83000 Hermosillo, Sonora (Mexico)

    2007-06-20

    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.

  19. Nucleic acid-lipid membrane interactions studied by DSC.

    Science.gov (United States)

    Giatrellis, Sarantis; Nounesis, George

    2011-01-01

    The interactions of nucleic acids with lipid membranes are of great importance for biological mechanisms as well as for biotechnological applications in gene delivery and drug carriers. The optimization of liposomal vectors for clinical use is absolutely dependent upon the formation mechanisms, the morphology, and the molecular organization of the lipoplexes, that is, the complexes of lipid membranes with DNA. Differential scanning calorimetry (DSC) has emerged as an efficient and relatively easy-to-operate experimental technique that can straightforwardly provide data related to the thermodynamics and the kinetics of the DNA-lipid complexation and especially to the lipid organization and phase transitions within the membrane. In this review, we summarize DSC studies considering nucleic acid-membrane systems, accentuating DSC capabilities, and data analysis. Published work involving cationic, anionic, and zwitterionic lipids as well as lipid mixtures interacting with RNA and DNA of different sizes and conformations are included. It is shown that despite limitations, issues such as DNA- or RNA-induced phase separation and microdomain lipid segregation, liposomal aggregation and fusion, alterations of the lipid long-range molecular order, as well as membrane-induced structural changes of the nucleic acids can be efficiently treated by systematic high-sensitivity DSC studies.

  20. Nucleic acid-lipid membrane interactions studied by DSC

    Directory of Open Access Journals (Sweden)

    Sarantis Giatrellis

    2011-01-01

    Full Text Available The interactions of nucleic acids with lipid membranes are of great importance for biological mechanisms as well as for biotechnological applications in gene delivery and drug carriers. The optimization of liposomal vectors for clinical use is absolutely dependent upon the formation mechanisms, the morphology, and the molecular organization of the lipoplexes, that is, the complexes of lipid membranes with DNA. Differential scanning calorimetry (DSC has emerged as an efficient and relatively easy-to-operate experimental technique that can straightforwardly provide data related to the thermodynamics and the kinetics of the DNA-lipid complexation and especially to the lipid organization and phase transitions within the membrane. In this review, we summarize DSC studies considering nucleic acid-membrane systems, accentuating DSC capabilities, and data analysis. Published work involving cationic, anionic, and zwitterionic lipids as well as lipid mixtures interacting with RNA and DNA of different sizes and conformations are included. It is shown that despite limitations, issues such as DNA- or RNA-induced phase separation and microdomain lipid segregation, liposomal aggregation and fusion, alterations of the lipid long-range molecular order, as well as membrane-induced structural changes of the nucleic acids can be efficiently treated by systematic high-sensitivity DSC studies.

  1. Dynamic Study of Gemini Surfactant and Single-chain Surfactant at Air/Water Interface

    Institute of Scientific and Technical Information of China (English)

    Yi Jian CHEN; Gui Ying XU; Shi Ling YUAN; Hai Ying SUN

    2005-01-01

    Molecular dynamics (MD) simulation are used to study the properties of gemini surfactant of ethyl-α,ω-bis(dodecyldimethylammonium bromide) (C12C2C12) and dodecyltrimethylammonium bromide (DTAB) at the air/water interface, respectively. In the two systems,the surfactant concentrations are both 28 wt. %, and other conditions are also the same. After reaching the thermodynamic equilibrium, the concentration profiles, the radial distributions functions (RDF) and the mean squared displacement (MSD) are investigated. Theresults reveal that the surface activity of C12C2C12 suffactant is higher than DTAB surfactant.

  2. STRUCTURE AND MORPHOLOGY CHANGES OF HYDROBIOTITES MODIFIED BY CATIONIC SURFACTANTS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this study, X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) together with Scanning probe microscopy (SPM) were used to characterize the structure and morphology of the complexes, where the hydrobiotites (Xinjiang) were modified by single-chain surfactants octyltrimethylammonium bromide (OTMA) and octadecyltrimethylammonium bromide (ODTMA). XRD patterns showed that the structure of complexes was significantly influenced by the surfactant concentration and the alkyl chain length, because obvious changes took place in the basal spacing. Furthermore, according to the XRD results, several arrangements of surfactant molecules within the hydrobiotite interlayer space were deduced. The FTIR spectrum indicated that the surfactant contents in complexes dramatically increased with the alkyl chain length. The SPM micrographs demonstrated that the surfaces of complexes prepared at lower surfactant concentration were relatively flat compared with that prepared at higher concentration, while those with higher surfactant concentration had much steeper surface due to the alkyl chain length. It was concluded that structure and morphology of surfactant/hydrobiotite complexes depend not only on the surfactant concentration, but also strongly on the surfactant species.

  3. Investigation of Polymer-Surfactant and Polymer-Drug-Surfactant Miscibility for Solid Dispersion.

    Science.gov (United States)

    Gumaste, Suhas G; Gupta, Simerdeep Singh; Serajuddin, Abu T M

    2016-09-01

    In a solid dispersion (SD), the drug is generally dispersed either molecularly or in the amorphous state in polymeric carriers, and the addition of a surfactant is often important to ensure drug release from such a system. The objective of this investigation was to screen systematically polymer-surfactant and polymer-drug-surfactant miscibility by using the film casting method. Miscibility of the crystalline solid surfactant, poloxamer 188, with two commonly used amorphous polymeric carriers, Soluplus® and HPMCAS, was first studied. Then, polymer-drug-surfactant miscibility was determined using itraconazole as the model drug, and ternary phase diagrams were constructed. The casted films were examined by DSC, PXRD and polarized light microscopy for any crystallization or phase separation of surfactant, drug or both in freshly prepared films and after exposure to 40°C/75% RH for 7, 14, and 30 days. The miscibility of poloxamer 188 with Soluplus® was <10% w/w, while its miscibility with HPMCAS was at least 30% w/w. Although itraconazole by itself was miscible with Soluplus® up to 40% w/w, the presence of poloxamer drastically reduced its miscibility to <10%. In contrast, poloxamer 188 had minimal impact on HPMCAS-itraconazole miscibility. For example, the phase diagram showed amorphous miscibility of HPMCAS, itraconazole, and poloxamer 188 at 54, 23, and 23% w/w, respectively, even after exposure to 40°C/75% RH for 1 month. Thus, a relatively simple and practical method of screening miscibility of different components and ultimately physical stability of SD is provided. The results also identify the HPMCAS-poloxamer 188 mixture as an optimal surface-active carrier system for SD.

  4. Binding of alkylpyridinium chloride surfactants to sodium polystyrene sulfonate

    NARCIS (Netherlands)

    Ishiguro, M.; Koopal, L.K.

    2009-01-01

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

  5. 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.

  6. Anaerobic Biodegradation of Detergent Surfactants

    OpenAIRE

    Erich Jelen; Ute Merrettig-Bruns

    2009-01-01

    Detergent surfactantscan be found in wastewater in relevant concentrations. Most of them are known as ready degradable under aerobic conditions, as required by European legislation. Far fewer surfactants have been tested so far for biodegradability under anaerobic conditions. The natural environment is predominantly aerobic, but there are some environmental compartments such as river sediments, sub-surface soil layer and anaerobic sludge digesters of wastewater treatment plants which have str...

  7. 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.

  8. Air Stripping of Ammonia from High-concentration Ammonia Wastewater with Surfactant as Third Component%气流与第三方物质交互解吸高浓度氨氮废水的研究

    Institute of Scientific and Technical Information of China (English)

    龚凡杰; 王光华; 孙明东; 鲁云洲; 荣先萍; 刘铁军

    2012-01-01

    An experiment was conducted on a bench-scale packed tower used as an air stripper, with a kind of surfactant added as the third component, to remove ammonia from a stream of high-concentration ammonia waste water. Parameters, including pH, temperature, n( volume ratio of air to liquid )and ρ( dose of the surfactant added), were studied about their influences on stripping efficiency, and the result showed addition of the surfactant could increase ammonia removal efficiency by 2%. Eventually, the experiment led to the optimum condition for ammonia stripping in terms of temperature and pH, with the ammonia concentration after treatment as low as that needed for the consequent secondary biological treatment of wastewater.%利用填料塔作为吹脱解吸设备,结合表面活性剂增强传质的特点,选取表面活性剂作为第三方物质,以空气作为气流吹脱解吸废水中的高浓度氨氮.实验研究了废水温度T、pH值、气液比n、表面活性剂种类和投加量ρ等条件变化对氨氮解吸效率η的影响.结果表明:加入表面活性剂X后,氨氮脱除效率提高2%;影响解吸效率因素的主次顺序为pH>T>n>ρ;最佳操作条件为T=80℃、pH=11.0、ρ=15 mg/L、n=650∶1.在最佳的操作条件下,处理氨氮含量为2159.0 mg/L和3680.5 mg/L的废水时,解吸效率分别达到95.28%和94.69%,即废水最终的氨氮浓度为102.0 mg/L和195.5 mg/L,低于废水后续生化处理进水指标中对氨氮含量的要求.

  9. 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

  10. Branched alkyl alcohol propoxylated sulfate surfactants for improved oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.; Iglauer, S.; Shuler, P.; Tang, Y. [California Institute of Technology, Covina, CA (US). Power, Environmental and Energy Research (PEER) Center; Goddard, W.A. III [California Institute of Technology, Pasadena, CA (United States). Materials and Process Simulation Center

    2010-05-15

    This investigation considers branched alkyl alcohol propoxylated sulfate surfactants as candidates for chemical enhanced oil recovery (EOR) applications. Results show that these anionic surfactants may be preferred candidates for EOR as they can be effective at creating low interfacial tension (IFT) at dilute concentrations, without requiring an alkaline agent or cosurfactant. In addition, some of the formulations exhibit a low IFT at high salinity, and hence may be suitable for use in more saline reservoirs. Adsorption tests onto kaolinite clay indicate that the loss of these surfactants can be comparable to or greater than other types of anionic surfactants. Surfactant performance was evaluated in oil recovery core flood tests. Selected formulations recovered 35-50% waterflood residual oil even with dilute 0.2 wt% surfactant concentrations from Berea sandstone cores. (orig.)

  11. Gemini imidazolium surfactants: synthesis and their biophysiochemical study.

    Science.gov (United States)

    Kamboj, Raman; Singh, Sukhprit; Bhadani, Avinash; Kataria, Hardeep; Kaur, Gurcharan

    2012-08-21

    New gemini imidazolium surfactants 9-13 have been synthesized by a regioselective epoxy ring-opening reaction under solvent-free conditions. The surface properties of these new gemini surfactants were evaluated by surface tension and conductivity measurements. These surfactants have been found to have low critical micelle concentration (cmc) values as compared to other categories of gemini cationic surfactants and also showed the tendency to form premicellar aggregates in solution at sufficiently low concentration below their cmc values. The thermal degradation of these surfactants was determined by thermograviometry analysis (TGA). These new cationic surfactants have a good DNA binding capability as determined by agarose gel electrophoresis and ethidium bromide exclusion experiments. They have also been found to have low cytotoxicity by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on the C6 glioma cell line.

  12. Effects of silicon surfactant in rigid polyurethane foams

    Directory of Open Access Journals (Sweden)

    2008-03-01

    Full Text Available The rigid polyurethane foams (RPUFs have been fabricated from high functional crude 4,4’-di-phenylmethane diisocyanate (CMDI and polypropylene glycols (PPGs for a wide range of surfactant concentration with an environmently friendly blowing agent (HFC 365mfc. Cream time, gel time, and tack-free time increased with the addition of surfactant. Foam density decreased rapidly to a minimum at 0.5 pphp (part per hundred polyol surfactant due to the increased blowing efficiency with surfactant. Surface tension rapidly decreased to an asymptotic value at 2 pphp surfactant. In accordance with this, cell size decreased and closed cell content increased rapidly to constant values at low surfactant concentrations (<1 pphp. The decrease of cell size was accompanied by the decrease of thermal conductivity to give a linear relatiohship between the two implying that the series model of heat transfer is applicable.

  13. POLYMERIC SURFACTANT STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    P.M. Saville; J.W. White

    2001-01-01

    Polymeric surfactants are amongst the most widespread of all polymers. In nature, proteins and polysaccharides cause self organization as a result of this surfactancy; in industry, polymeric surfactants play key roles in the food, explosives and surface coatings sectors. The generation of useful nano- and micro-structures in films and emulsions as a result of polymer amphiphilicity and the application of mechanical stress is discussed. The use of X-ray and neutron small angle scattering and reflectivity to measure these structures and their dynamic properties will be described. New results on linear and dendritic polymer surfactants are presented.

  14. Dendrimer-surfactant interactions.

    Science.gov (United States)

    Cheng, Yiyun; Zhao, Libo; Li, Tianfu

    2014-04-28

    In this article, we reviewed the interactions between dendrimers and surfactants with particular focus on the interaction mechanisms and physicochemical properties of the yielding dendrimer-surfactant aggregates. In order to provide insight into the behavior of dendrimers in biological systems, the interactions of dendrimers with bio-surfactants such as phospholipids in bulk solutions, in solid-supported bilayers and at the interface of phases or solid-states were discussed. Applications of the dendrimer-surfactant aggregates as templates to guide the synthesis of nanoparticles and in drug or gene delivery were also mentioned.

  15. Competitive adsorption of surfactants and hydrophilic silica particles at the oil-water interface: interfacial tension and contact angle studies.

    Science.gov (United States)

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

    2012-07-01

    The effect of surfactants' type and concentration on the interfacial tension and contact angle in the presence of hydrophilic silica particles was investigated. Silica particles have been shown to have an antagonistic effect on interfacial tension and contact angle in the presence of both W/O and O/W surfactants. Silica particles, combined with W/O surfactant, have no effect on interfacial tension, which is only dictated by the surfactant concentration, while they strongly affect interfacial tension when combined with O/W surfactants. At low O/W surfactant, both particles and surfactant are adsorbed at the interface, modifying the interface structure. At higher concentration, interfacial tension is only dictated by the surfactant. By increasing the surfactant concentration, the contact angle that a drop of aqueous phase assumes on a glass substrate placed in oil media decreases or increases depending on whether the surfactant is of W/O or O/W type, respectively. This is due to the modification of the wettability of the glass by the oil or water induced by the surfactants. Regardless of the surfactant's type, the contact angle profile was dictated by both particles and surfactant at low surfactant concentration, whereas it is dictated by the surfactant only at high concentration.

  16. Application of experimental design in examination of the dissolution rate of carbamazepine from formulations: Characterization of the optimal formulation by DSC, TGA, FT-IR and PXRD analysis

    Directory of Open Access Journals (Sweden)

    Krstić Marko

    2015-01-01

    Full Text Available Poor solubility is one of the key reasons for the poor bioavailability of these drugs. This paper displays a formulation of a solid surfactant system with carbamazepine, in order to increase its dissolution rate. Solid state surfactant systems are formed by application of fractal experimental design. Poloxamer 237 and Poloxamer 338 were used as surfactants and Brij® 35 was used as the co-surfactant. The ratios of the excipients and carbamazepine were varied and their effects on the dissolution rate of carbamazepine were examined. Moreover, the effects of the addition of natural (diatomite and a synthetic adsorbent carrier (Neusiline UFL2 on the dissolution rate of carbamazepine were also tested. The prepared surfactant systems were characterized and the influence of the excipients on possible changes of the polymorphous form of carbamazepine examined by application of analytical techniques (DSC, TGA, FT-IR, PXRD. It was determined that an appropriate selection of the excipient type and ratio could provide a significant increase in the carbamazepine dissolution rate. By application of analytical techniques, it was found that that the employed excipients induce a transition of carbamazepine into the amorphous form and that the selected sample was stable for three months, when kept under ambient conditions. [Projekat Ministarstva nauke Republike Srbije, br. TR34007

  17. Surfactant Sector Needs Urgent Readjustment

    Institute of Scientific and Technical Information of China (English)

    Huang Hongzhou

    2007-01-01

    @@ Surfactant industrial system has been basically established After 50 years' development, China has already established a surfactant industrial system with a relatively complete product portfolio and can produce 4714 varieties of surfactants in cationic,anionic, nonionic and amphoteric categories.

  18. Performance of some surfactants as wetting agents

    Energy Technology Data Exchange (ETDEWEB)

    Shalaby, M.N.; El-Shanny, O.A.A. [Egyptian Petroleum Research Institute (EPRI), Cairo (Egypt). Evaluation and Analysis Dept.

    2005-12-01

    The wetting power of anionic surfactant: sodium dodecyl sulfate (SDS), and nonionic surfactants: polyoxyethelene(14)monolaurate [La(EO){sub 14}] and polyoxyethelene(14)monoeleate [OI(EO){sub 14}] has been studied to determine their performance as wetting agents. The study reveals that the nonionic compound with a long hydrophobic chain exhibits higher wettability than the shorter one when used at very low cocentrations (below CMC) and the reverse is shown with high concentrations (above CMC). the wetting power of the investigated surfactants increases as the CMC values increases. In case of the nonionic compounds and at surfactant concentrations equal their CMC values, OI(EO){sub 14} shows a higher wetting power than La(EO){sub 14} while is possesses a lower HLB value. The anionic surfactant shows an optimum wetting in comparison with the tested nonionic one. The wettability of all the investigated samples increases as the surface tension of their solutions increases to the allowed limit that can be reached in the presence of surfactant. (orig.)

  19. [Liposome phospholipid substitution and lung function in surfactant deprived rats].

    Science.gov (United States)

    Obladen, M

    1985-01-01

    In vivo activity of an artificial surfactant was studied in surfactant depleted rats. After tenfold alveolar lavage, PaO2, tidal volume, and compliance of the respiratory system fell to one third of initial value. Substitution of large unilamellar vesicles containing 90% Dipalmitoylphosphatidylcholine and 10% unsaturated phosphatidylglycerol largely restored oxygenation and lung mechanics in most animals. Complete normalization with weaning from the ventilator, however, was achieved neither with liposomes nor with natural surfactant concentrate.

  20. Thermogravimetric and DSC testing of poly(lactic acid) nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Mróz, Patrycja; Białas, Sylwia [Faculty of Process and Environmental Engineering, Technical University of Łódź, Wólczańska 15 Street, 90-924 Łódź (Poland); Mucha, Maria, E-mail: muchama@wipos.p.lodz.pl [Faculty of Process and Environmental Engineering, Technical University of Łódź, Wólczańska 15 Street, 90-924 Łódź (Poland); Kaczmarek, Halina [Nicolaus Copernicus University, Faculty of Chemistry, Gagarin 7 Street, 87-100 Toruń (Poland)

    2013-12-10

    Highlights: • The presence of nanoadditivities in PLA matrix improves thermal stability of PLA. • Shielding effect main reason for PLA thermal stability by nanofillers. • Thermal degradation suppression in UV-irradiated PLA by the removing of unstable compounds. - Abstract: Polymer nanocomposites based on poly(lactic acid), PLA, and two types of nanofillers: nanosilver and nanoclay were obtained by casting method. The thermal properties of PLA and nanocomposites have been studied by thermogravimetric analysis (TA) and differential scanning calorimetry (DSC). All samples have been UV-irradiated and the effect of photoprocess on their thermal stability has been estimated. It was found that nanoadditives and UV irradiation causes an increase of the activation energy of PLA thermal decomposition. DSC result supplies information on glass transition and crystallization/melting processes in PLA in the presence of nanosilver or nanoclay, also after exposure to UV.

  1. Some Remarks on the Degree of Crystallinity Measured on DSC

    Institute of Scientific and Technical Information of China (English)

    邱高; 唐志廉; 黄南薰

    2001-01-01

    A modified mathematical model based on the melting and recrystallization of an initial distribution of melting temperatures predicts the melting behavior of polymer in differential scanning calorimetry ( DSC ), taking into account of changes in heat of fusion with melting temperature of crystal and average heat capacity of sample. It has been used to analytically prove that the crystallinity measured on a DSC diagram could not be equal to the weight percentage of crystalline state in the initial specimen. The deviation of the measured crystallinity, as observed relevant to the melting and recrystallization processes, is caused by the changes of the heat of fusion with the melting temperature of crystals, as well as the difference of heat capacities of liquld and solid state polymer. Furthermore, upper and lower limits of the deviation have been discussed.

  2. Interactions of tamoxifen with distearoyl phosphatidylcholine multilamellar vesicles: FTIR and DSC studies.

    Science.gov (United States)

    Bilge, Duygu; Sahin, Ipek; Kazanci, Nadide; Severcan, Feride

    2014-09-15

    Interactions of a non-steroidal antiestrogen drug, tamoxifen (TAM), with distearoyl-sn-glycero-3-phosphatidylcholine (DSPC) multilamellar liposomes (MLVs) were investigated as a function of drug concentration (1-15 mol%) by using two noninvasive techniques, namely Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). FTIR spectroscopy results show that increasing TAM concentrations (except 1 mol%) increased the wavenumbers of the CH2 stretching modes, implying an disordering effect for DSPC MLVs both in the gel and liquid crystalline phases. The bandwidth values of the CH2 stretchings except for 1 mol% increased when TAM concentrations increased for DSPC liposomes, indicating an increase in the dynamics of liposomes. The CO stretching and PO2- antisymmetric double bond stretching bands were analyzed to study interactions of TAM with head groups of lipids. As the concentrations of TAM increased, dehydration occurred around these functional groups in the polar part of the lipids. The DSC studies on thermal properties of DSPC lipids indicate that TAM eliminated the pre transition, shifted the main phase transition to lower temperatures and broadened the phase transition curve of the liposomes.

  3. A novel compound DSC suppresses lipopolysaccharide-induced inflammatory responses by inhibition of Akt/NF-κB signalling in macrophages.

    Science.gov (United States)

    Liu, Xin-Hua; Pan, Li-Long; Jia, Yao-Ling; Wu, Dan; Xiong, Qing-Hui; Wang, Yang; Zhu, Yi-Zhun

    2013-05-15

    A novel compound [4-(2-acetoxy-3-((R)-3-(benzylthio)-1-methoxy-1-oxopropan-2-ylamino)-3-oxopropyl)-1,2-phenylene diacetate (DSC)], derived from Danshensu, exerted cytoprotective effects by anti-oxidative and anti-apoptotic activities in vitro. Herein, we reported the protective effects of DSC on lipopolysaccharide (LPS)-induced inflammatory responses in murine RAW264.7 macrophages and the underlying mechanisms. We showed that DSC concentration-dependently attenuated nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression with less cytotoxicity. Signal transduction studies indicated that DSC significantly inhibited LPS-induced phosphorylation of Akt, but not c-Jun N-terminal kinase 1/2, p38, or extracellular signal-regulated kinase 1/2. Meanwhile, LPS-induced nuclear translocation of nuclear factor-κB (NF-κB) p65 was decreased by DSC. Furthermore, a phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 significantly suppressed LPS-induced NF-κB p65 nuclear translocation, iNOS expression, and NO production, which was also mimicked by pretreatment with DSC. These results suggested that DSC attenuated LPS-induced inflammatory response in macrophages, at least in part, through suppression of PI3K/Akt signaling and NF-κB activation.

  4. Foaming and foam stability for mixed polymer-surfactant solutions: effects of surfactant type and polymer charge.

    Science.gov (United States)

    Petkova, R; Tcholakova, S; Denkov, N D

    2012-03-20

    Solutions of surfactant-polymer mixtures often exhibit different foaming properties, compared to the solutions of the individual components, due to the strong tendency for formation of polymer-surfactant complexes in the bulk and on the surface of the mixed solutions. A generally shared view in the literature is that electrostatic interactions govern the formation of these complexes, for example between anionic surfactants and cationic polymers. In this study we combine foam tests with model experiments to evaluate and explain the effect of several polymer-surfactant mixtures on the foaminess and foam stability of the respective solutions. Anionic, cationic, and nonionic surfactants (SDS, C(12)TAB, and C(12)EO(23)) were studied to clarify the role of surfactant charge. Highly hydrophilic cationic and nonionic polymers (polyvinylamine and polyvinylformamide, respectivey) were chosen to eliminate the (more trivial) effect of direct hydrophobic interactions between the surfactant tails and the hydrophobic regions on the polymer chains. Our experiments showed clearly that the presence of opposite charges is not a necessary condition for boosting the foaminess and foam stability in the surfactant-polymer mixtures studied. Clear foam boosting (synergistic) effects were observed in the mixtures of cationic surfactant and cationic polymer, cationic surfactant and nonionic polymer, and anionic surfactant and nonionic polymer. The mixtures of anionic surfactant and cationic polymer showed improved foam stability, however, the foaminess was strongly reduced, as compared to the surfactant solutions without polymer. No significant synergistic or antagonistic effects were observed for the mixture of nonionic surfactant (with low critical micelle concentration) and nonionic polymer. The results from the model experiments allowed us to explain the observed trends by the different adsorption dynamics and complex formation pattern in the systems studied.

  5. Effects of Surfactant on Solubility and Microbial Conversion of Steroid

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Enhancing the dispersion and dissolution of substrate particles in substrate/water suspension is a feasible way to improve steroid bioconversion. The aim of the present study is to investigate the effects of applying surfactant to microbial conversion system on the dispersion, solubilization and in turn bioconversion of steroid substrate. The model system is hydroxylation of substrate 16α-,17α-epoxy-4-pregnene-3,20-dine by microbial enzymes from Rhizopus nigricanl. The results show that the presence of substrate leads to an increase in critical micelle concentration (CMC) of surfactant PSE compared with the normal CMC of PSE in aqueous solution. The grinding time during substrate suspension preparation affects the substrate aqueous solubility differently with the varied surfactant concentrations while barely making any difference in substrate solubility in the absence of surfactant. The properly prolonged grinding time can make up for the loss in substrate solubility arising from the reduction in surfactant concentration. The surfactant complexes composed of surfactants PSE and MGE at appropriate ratios are screened out with orthodoxy experiment method, the interaction between PSE and MGE exerts the most prominent effects on substrate bioconversion, and the surfactant complexes show more beneficial effects on steroid bioconversion than the surfactant PSE used alone.

  6. Surfactant Based Enhanced Oil Recovery and Foam Mobility Control

    Energy Technology Data Exchange (ETDEWEB)

    George J. Hirasaki; Clarence A. Miller

    2006-09-09

    Surfactant flooding has the potential to significantly increase recovery over that of conventional waterflooding. The availability of a large number of surfactant structures makes it possible to conduct a systematic study of the relation between surfactant structure and its efficacy for oil recovery. A mixture of two surfactants was found to be particularly effective for application in carbonate formations at low temperature. The mixture is single phase for higher salinity or calcium concentrations than that for either surfactant used alone. This makes it possible to inject the surfactant slug with polymer close to optimal conditions and yet be single phase. A formulation has been designed for a particular field application. It uses partially hydrolyzed polyacrylamide for mobility control. The addition of an alkali such as sodium carbonate makes possible in situ generation of naphthenic soap and significant reduction of synthetic surfactant adsorption. The design of the process to maximize the region of ultra-low IFT takes advantage of the observation that the ratio of soap to synthetic surfactant is a parameter in the conditions for optimal salinity. Even for a fixed ratio of soap to surfactant, the range of salinity for low IFT was wider than that reported for surfactant systems in the literature. Low temperature, forced displacement experiments in dolomite and silica sandpacks demonstrate that greater than 95% recovery of the waterflood remaining oil is possible with 0.2% surfactant concentration, 0.5 PV surfactant slug, with no alcohol. Compositional simulation of the displacement process demonstrates the role of soap/surfactant ratio on passage of the profile through the ultralow IFT region, the importance of a wide salinity range of low IFT, and the importance of the viscosity of the surfactant slug. Mobility control is essential for surfactant EOR. Foam is evaluated to improve the sweep efficiency of surfactant injected into fractured reservoirs as well as a

  7. Evaluation of passive samplers with neutral or ion-exchange polymer coatings to determine freely dissolved concentrations of the basic surfactant lauryl diethanolamine: Measurements of acid dissociation constant and organic carbon-water sorption coefficient.

    Science.gov (United States)

    Wang, Fang; Chen, Yi; Hermens, Joop L M; Droge, Steven T J

    2013-11-08

    A passive sampler tool (solid-phase microextraction, SPME) was optimized to measure freely dissolved concentrations (Cw,free) of lauryl diethanolamine (C12-DEA). C12-DEA can be protonated and act as a cationic surfactant. From the pH-dependent sorption to neutral SPME coatings (polyacrylate and PDMS), a pKa of 8.7 was calculated, which differs more than two units from the value of 6.4 reported elsewhere. Polyacrylate coated SPME could not adequately sample largely protonated C12-DEA in humic acid solutions of pH 6. A new hydrophobic SPME coating with cation-exchange properties (C18/SCX) sorbed C12-DEA 100 fold stronger than polyacrylate, because it specifically sorbs protonated C12-DEA species. The C18/SCX-SPME fiber showed linear calibration isotherms in a concentration range of <1 nM-1 μM (well below the CMC). Using the C18/SCX-SPME fibers, linear sorption isotherms to Aldrich humic acid at pH 6 (ionic strength 0.015 M) were measured over a broad concentration range with a sorption coefficient of 10(5.3).

  8. SURFACTANTS IN LUBRICATION

    Science.gov (United States)

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

  9. 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. Re

  10. Determinação potenciométrica da concentração micelar crítica de surfactantes: uma nova aplicação metodológica no ensino de Química Potenciometric determination of the critical micellar concentration of the surfactants: a new methodological application in the Chemical learning

    Directory of Open Access Journals (Sweden)

    Ivanise Mª Rizzatti

    2009-01-01

    Full Text Available The participation of the students in the planning, execution and discussion of experimental results is important for the valuation of the role of them in the construction of the chemical knowledge implicited in the approach between education and research. This work relates either the construction of selective membrane electrodes for surfactants and its application in the potenciometric determination of the critical micellar concentration of the sodium dodecyl sulfate (SDS and dodecyltrimethylammonium bromide (DTAB surfactants. In adition it´s possible to discuss the potenciometric results in matching with the data valued for the tensiometric and condutimetric traditionally used in the physical-chemistry lessons.

  11. Phase diagrams of DNA-photosensitive surfactant complexes: effect of ionic strength and surfactant structure.

    Science.gov (United States)

    Zakrevskyy, Yuriy; Titov, Evgenii; Lomadze, Nino; Santer, Svetlana

    2014-10-28

    Realization of all-optically controlled and efficient DNA compaction is the major motivation in the study of interactions between DNA and photosensitive surfactants. In this article, using recently published approach of phase diagram construction [Y. Zakrevskyy, P. Cywinski, M. Cywinska, J. Paasche, N. Lomadze, O. Reich, H.-G. Löhmannsroben, and S. Santer, J. Chem. Phys. 140, 044907 (2014)], a strategy for substantial reduction of compaction agent concentration and simultaneous maintaining the light-induced decompaction efficiency is proposed. The role of ionic strength (NaCl concentration), as a very important environmental parameter, and surfactant structure (spacer length) on the changes of positions of phase transitions is investigated. Increase of ionic strength leads to increase of the surfactant concentration needed to compact DNA molecule. However, elongation of the spacer results to substantial reduction of this concentration. DNA compaction by surfactants with longer tails starts to take place in diluted solutions at charge ratios Z phase diagrams for different DNA-photosensitive surfactant systems allowed explanation and proposal of a strategy to overcome previously reported limitations of the light-induced decompaction for complexes with increasing surfactant hydrophobicity.

  12. Assessment of interactions between four proteins and benzothiazole derivatives by DSC and CD

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Natalia [Soft Matter and Molecular Biophysics Group, Department of Applied Physics, Faculty of Physics, Campus Vida, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Verdes, Pedro V., E-mail: pedro.vazquez@usc.e [Soft Matter and Molecular Biophysics Group, Department of Applied Physics, Faculty of Physics, Campus Vida, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Ruso, Juan M. [Soft Matter and Molecular Biophysics Group, Department of Applied Physics, Faculty of Physics, Campus Vida, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain)

    2011-03-15

    The thermal denaturation of ovalbumin, lysozyme, myoglobin and fibrinogen at different BTS concentrations have been investigated using differential scanning calorimetry (DSC) and circular dichroism (CD) spectroscopy. Thermodynamic parameters: melting temperatures (T{sub m}), calorimetric enthalpy ({Delta}H), van't Hoff enthalpy ({Delta}H{sub v}) were obtained for all the systems under study. Thermal denaturation of the four proteins was completely irreversible. Changes in the protein conformation due to the adsorption of BTS molecules have been monitored by using UV-CD spectra. Greater changes in {alpha}-helical contents correspond with the BTS higher concentrations. The lysozyme denaturation temperature increases at low concentrations BTS indicating that BTS acts as a structure stabilizer; meanwhile it acts as a destabilizer at higher concentrations in all the proteins studied. The major effect is observed in the case of myoglobin, the protein with the highest {alpha}-helical secondary structure (75%).

  13. Nanotube Dispersions Made With Charged Surfactant

    Science.gov (United States)

    Kuper, Cynthia; Kuzma, Mike

    2006-01-01

    Dispersions (including monodispersions) of nanotubes in water at relatively high concentrations have been formulated as prototypes of reagents for use in making fibers, films, and membranes based on single-walled carbon nanotubes (SWNTs). Other than water, the ingredients of a dispersion of this type include one or more charged surfactant(s) and carbon nanotubes derived from the HiPco(TradeMark) (or equivalent) process. Among reagents known to be made from HiPco(TradeMark)(or equivalent) SWNTs, these are the most concentrated and are expected to be usable in processing of bulk structures and materials. Test data indicate that small bundles of SWNTs and single SWNTs at concentrations up to 1.1 weight percent have been present in water plus surfactant. This development is expected to contribute to the growth of an industry based on applied carbon nanotechnology. There are expected to be commercial applications in aerospace, avionics, sporting goods, automotive products, biotechnology, and medicine.

  14. Pulmonary surfactant adsorption is increased by hyaluronan or polyethylene glycol.

    Science.gov (United States)

    Taeusch, H William; Dybbro, Eric; Lu, Karen W

    2008-04-01

    In acute lung injuries, inactivating agents may interfere with transfer (adsorption) of pulmonary surfactants to the interface between air and the aqueous layer that coats the interior of alveoli. Some ionic and nonionic polymers reduce surfactant inactivation in vitro and in vivo. In this study, we tested directly whether an ionic polymer, hyaluronan, or a nonionic polymer, polyethylene glycol, enhanced adsorption of a surfactant used clinically. We used three different methods of measuring adsorption in vitro: a modified pulsating bubble surfactometer; a King/Clements device; and a spreading trough. In addition we measured the effects of both polymers on surfactant turbidity, using this assay as a nonspecific index of aggregation. We found that both hyaluronan and polyethylene glycol significantly increased the rate and degree of surfactant material adsorbed to the surface in all three assays. Hyaluronan was effective in lower concentrations (20-fold) than polyethylene glycol and, unlike polyethylene glycol, hyaluronan did not increase apparent aggregation of surfactant. Surfactant adsorption in the presence of serum was also enhanced by both polymers regardless of whether hyaluronan or polyethylene glycol was included with serum in the subphase or added to the surfactant applied to the surface. Therefore, endogenous polymers in the alveolar subphase, or exogenous polymers added to surfactant used as therapy, may both be important for reducing inactivation of surfactant that occurs with various lung injuries.

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

    DEFF Research Database (Denmark)

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

    2005-01-01

    The rate of change of surface pressure, pi, in a Langmuir trough following the deposition of surfactant suspensions on subphases containing serum, with or without polymers, is used to model a likely cause of surfactant inactivation in vivo: inhibition of surfactant adsorption due to competitive...... adsorption of surface active serum proteins. Aqueous suspensions of native porcine surfactant, organic extracts of native surfactant, and the clinical surfactants Curosurf, Infasurf, and Survanta spread on buffered subphases increase the surface pressure, pi, to approximately 40 mN/m within 2 min....... The variation with concentration, temperature, and mode of spreading confirmed Brewster angle microscopy observations that subphase to surface adsorption of surfactant is the dominant form of surfactant transport to the interface. However (with the exception of native porcine surfactant), similar rapid...

  16. Flexible polyelectrolyte conformation in the presence of cationic and anionic surfactants

    Science.gov (United States)

    Passos, C. B.; Kuhn, P. S.; Diehl, A.

    2015-11-01

    In this work we have studied the conformation of flexible polyelectrolyte chains in the presence of cationic and anionic surfactant molecules. We developed a simple theoretical model for the formation of the polyelectrolyte-cationic surfactant complexes and mixed micelles formed by cationic and anionic surfactant molecules, in the framework of the Debye-Hückel-Bjerrum-Manning and Flory theories, with the hydrophobic interaction included explicitly as an effective short-ranged attraction between the surfactant hydrocarbon tails. This simple model allows us to calculate the extension of the polyelectrolyte-cationic surfactant complexes as a function of the anionic surfactant concentration, for different types of cationic and anionic surfactant molecules. A discrete conformational transition from a collapsed state to an elongated coil was found, for all surfactant chain lengths we have considered, in agreement with the experimental observations for the unfolding of ​DNA-cationic surfactant complexes.

  17. Effects of Surfactant Adsorption on Surficial Wettability of Nonwoven Fabrics

    Institute of Scientific and Technical Information of China (English)

    CAI Bing; TANG Bing; LI Rui-xia; WU Da-cheng

    2002-01-01

    All types of surfactants (cationic, anionic and nonionic)reported in this paper could enhance the surficiai wettability of polypropylene (PP) and polyethylene terephthalate (PET) nonwoven fabrics. However, the effects of cationic and nonionic surfactants were better.The longer the treatment time of surfactants on the nonwoven fabrics, the better the surficial wettability.The surficial rewetting time would no longer change above a certain treatment time. The rewettability of nonwoven fabrics could be evidently improved just when the concentration of surfactants was just above the CMC,except for sodium dodecylbenzene sulfonate (LAS). The finer the fibers and the looser the structures, the better the surficial rewettability of nonwoven fabrics.

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

    DEFF Research Database (Denmark)

    Boutrup Stephansen, Karen; García-Díaz, María; Jessen, Flemming

    2016-01-01

    ), a cationic surfactant (benzalkonium chloride), and a neutral surfactant (Triton X-100) were studied. The anionic surfactants increased the insulin release in a concentration-dependent manner, whereas the neutral surfactant had no significant effect on the release. Interestingly, only minute amounts...... of insulin were released from the fibers when benzalkonium chloride was present. The FSP-Ins fibers appeared dense after incubation with this cationic surfactant, whereas high fiber porosity was observed after incubation with anionic or neutral surfactants. Contact angle measurements and staining...

  19. 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.

  20. 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.

  1. Spinodal Decomposition in Mixtures Containing Surfactants

    Science.gov (United States)

    Melenekvitz, J.

    1998-03-01

    Spinodal decomposition in mixtures containing two immiscible liquids (A and B) plus surfactant was investigated using a recently developed (J. Melenkevitz and S. H. Javadpour, J. Chem. Phys., 107, 623 (1997).) 3-component Ginzburg-Landau model. The time dependent Ginzburg-Landau (TDGL) equations governing the evolution of structure were numerically integrated in 2-dimensions. We found the growth rate of the average domain size, R(t), decreased with increasing surfactant concentration over a wide range of relative amounts of A and B. This can be attributed to the surfactant accumulating at the growing interface between the immiscible liquids, which leads to a reduction in the surface tension. At late times, the growth rate was noticeably altered when thermal fluctuations were added to the numerical simulations. In this case, power law behavior was observed for R(t) at late times, R(t) ~ t^α, with the exponent α decreasing as the amount of surfactant increased. The dynamics at early times were determined by linearizing the TDGL equations about a uniformly mixed state. The growth rate at ealry times was found to be strongly dependent on the model parameters describing the surfactant miscibility in A and B and the surfactant strength. Comparison with recent measurements on SBR / PB mixtures with added PB-SBR diblock copolymer will also be presented.

  2. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2005-01-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Imbibition in an originally oil-wet 2D capillary is the fastest in the case of Alf-38 and slowest in the case of DTAB (among the surfactants studied). Force of adhesion studies and contact angle measurements show that greater wettability alteration is possible with these anionic surfactants than the cationic surfactant studied. The water imbibition rate does not increase monotonically with an increase in the surfactant concentration. A numerical model has been developed that fits the rate of imbibition. Plans for the next quarter include conducting simulation and imbibition studies.

  3. Self-healing Dynamics of Surfactant Coatings on Thin Viscous Films

    CERN Document Server

    Strickland, Stephen L; Sayanagi, M Richard; Conti, Cameron; Daniels, Karen E; Levy, Rachel

    2013-01-01

    We investigate the dynamics of an insoluble surfactant on the surface of a thin viscous fluid spreading inward to fill a surfactant-free region. During the initial stages of surfactant self-healing, Marangoni forces drive an axisymmetric ridge inward to coalesce into a growing central distension; this is unlike outward-spreading, in which the ridge decays. In later dynamics, the distension slowly decays and the surfactant concentration equilibrates. We present results from experiments in which we simultaneously measure the surfactant concentration (using fluorescently-tagged lipids) and the fluid height profile (via laser profilometry). We compare the results to simulations of a mathematical model using parameters from the experiments. For surfactant concentrations close to but below the critical monolayer concentration, we observe agreement between the height profiles in the numerical simulations and the experiment, but disagreement in the surfactant distribution. In experiments at lower concentrations, the ...

  4. 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

  5. Enrichment of surfactant from its aqueous solution using ultrasonic atomization.

    Science.gov (United States)

    Takaya, Haruko; Nii, Susumu; Kawaizumi, Fumio; Takahashi, Katsuroku

    2005-08-01

    Dilute aqueous solutions of dodecyl-benzenesulfonic acid sodium salt (DBS-Na) and polyoxyethylenenonylphenyl ethers (PONPEs) were ultrasonically atomized. The surfactants were concentrated in collected mist droplets. The enrichment ratio increased with decreasing surfactant concentration. Depending on the surfactant's molecular weight and affinity to water, different enrichment ratio was observed in the range of low feed concentrations. For anionic surfactant, DBS-Na, the enrichment ratio was significantly improved by KCl addition and a peak appeared on the plot of the ratio against KCl concentration. Addition of NaCl or CaCl2 . 2H2O to the surfactant solution also enhanced the enrichment ratio; however, the effect was relatively small. Such behaviors of the ratio were interpreted as enhanced interfacial adsorption of the surfactant and a lack of supply of surfactant monomers from liquid bulk because of slow breaking of surfactant micelles. Time required for collecting an amount of mist was also observed. Among the three salt systems, the time for KCl system was twice as long as others. This fact suggested that the formation of smaller droplets in KCl system.

  6. Coupled Transport of PAH and Surfactants in Natural Aquifer Material

    Science.gov (United States)

    Danzer, J.; Grathwohl, P.

    1998-03-01

    Surfactants in aqueous solution adsorb onto mineral surfaces and form micelles above the critical micelle concentration (CMC) due to their physico-chemical properties. Hydrophobic organic compounds such as polycyclic aromatic hydrocarbons (PAHs) have a high affinity for the adsorbed surfactant layers (monomers, hemimicelles and admicelles) and to the micelles in the mobile aqueous phase. The transport of PAHs is controlled by the concentration of the surfactant and the partition coefficients, of the PAHs between water and admicelles (adsolubilization: K adm) and water and micelles (solubilization: K mic), respectively. These partition coefficients were measured in laboratory batch and column experiments using phenanthrene as a chemical probe for the PAHs, a non-ionic surfactant (Terrasurf G50), natural aquifer sand (River Neckar Alluvium: RNA) and its petrographic subcomponents. The sorption of the surfactant can be described by a linear isotherm for concentrations below the CMC and a sorption maximum above the CMC, which both depend on the grain size and the surfactant accessible internal surface area of the particles. K adm was found to be higher than K mic. Both depend on the surfactant's properties, such as alkyl chain length, polar headgroup or ethoxylation. In column experiments an increasing retardation of phenanthrene was observed up to the CMC followed by a facilitated transport at surfactant concentration several times the CMC.

  7. Surfactants in the environment.

    Science.gov (United States)

    Ivanković, Tomislav; Hrenović, Jasna

    2010-03-01

    Surfactants are a diverse group of chemicals that are best known for their wide use in detergents and other cleaning products. After use, residual surfactants are discharged into sewage systems or directly into surface waters, and most of them end up dispersed in different environmental compartments such as soil, water or sediment. The toxic effects of surfactants on various aquatic organisms are well known. In general, surfactants are present in the environment at levels below toxicity and in Croatia below the national limit. Most surfactants are readily biodegradable and their amount is greatly reduced with secondary treatment in wastewater treatment plants. The highest concern is the release of untreated wastewater or wastewater that has undergone primary treatment alone. The discharge of wastewater polluted with massive quantities of surfactants could have serious effects on the ecosystem. Future studies of surfactant toxicities and biodegradation are necessary to withdraw highly toxic and non-biodegradable compounds from commercial use and replace them with more environmentally friendly ones.

  8. 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 th

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1992-03-01

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

  10. 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.

  11. A DSC STUDY OF PHOTOPOLYMERIZATION OF POLYESTERS CONTAINING CONJUGATED DIACETYLENES

    Institute of Scientific and Technical Information of China (English)

    Yao-wen Bai; Xiao-fang Chen; Dong Zhang; Xin-hua Wan; Qi-feng Zhou

    2000-01-01

    The photopolymerization of two kinds of prepolyesters containing conjugated diacetylene (PDA-6 and PDA-12)was investigated using DSC. By measuring the endothermic enthalpy of the prepolymers after different UV-irradiation times,the polymerizations were found to follow the first-order rate law which agreed with the results of other investigators using a different method. The endothermic enthalpy measurements of PDA-6 and PDA-12 before UV-irradiation precluded the possibility that the decrease of endothermic enthalpy was caused by thermal polymerization.

  12. Concentration of surfactant protein D, Clara cell protein CC-16 and IL-10 in bronchoalveolar lavage (BAL in patients with sarcoidosis, hypersensivity pneumonitis and idiopathic pulmonary fibrosis.

    Directory of Open Access Journals (Sweden)

    Wojciech Naumnik

    2009-12-01

    Full Text Available The process of interstitial inflammation, often chronic, goes fluently from alveolitis through granuloma formation to irreversible fibrosis and lung remodeling. Eventually, the loss of functional alveolar units leads to chronic respiratory failure. The pneumoproteins (e.g. SP-D, CC-16 are considered to be markers of interstitial inflammation. We measured BAL concentration of SP-D, CC-16 and IL-10 in patients with sarcoidosis (27, IPF (7 and HP (9. The level of each marker was determined by ELISA specific kit. We found the highest SP-D and CC-16 BAL concentration in patients with the III stage of sarcoidosis (96,67 ng/ml and 31,78 ng/ml, respectively. The lowest SP-D concentration was observed in patients with IPF (76,49 ng/ml, and the lowest CC-16 concentration in patients with HP (21,39 ng/ml. The differences were not statistically significant. In the group of the III stage of sarcoidosis higher SP-D levels were related to higher BAL cytosis and higher percentage of BAL neutrophils, just the opposite as in the IPF and HP group. In the III stage of sarcoidosis and HP, the lower SP-D levels, the lower FEV1 and VC values. The results show, that in acute interstitial inflammation with larger parenchyma engagement (III stage of sarcoidosis the levels of SP-D were higher then in chronic interstitial inflammation (IPF.

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

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Ahmadi

    2016-07-01

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

  14. Effects of a surfactant (FFD-6) on Scenedesmus morphology and growth under different nutrient conditions

    NARCIS (Netherlands)

    Lürling, M.F.L.L.W.

    2006-01-01

    Surfactants are man-made compounds that are meanwhile omnipresent in the environment, but environmental concentrations of surfactants are such that they are thought to have little risk for aquatic systems. The major anionic surfactants currently on the global market are linear alkylbenzene sulfonate

  15. Effects of a surfactant (FFD-6) on Scenedesmus morphology and growth under different nutrient conditions

    NARCIS (Netherlands)

    Lürling, M.F.L.L.W.

    2006-01-01

    Surfactants are man-made compounds that are meanwhile omnipresent in the environment, but environmental concentrations of surfactants are such that they are thought to have little risk for aquatic systems. The major anionic surfactants currently on the global market are linear alkylbenzene

  16. 索尼DSC-P200数码相机

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    作为面向普通家用的时尚主打机型,索尼DSC-P系列一直保持着相当高的市场份额,在DSC-P150把家用数码相机带到700万像素级后,索尼继续推出了DSC-P150的升级机型DSC-P200。

  17. Phase behavior of supercritical CO2 microemulsion with food-grade surfactant AOT

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yongsheng; AN Xueqin; SHEN Weiguo; ZHANG Yinghua

    2006-01-01

    Phase behavior of scCO2 microemulsion formed with food grade surfactant sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) was studied. Critical microemulsion concentration (cμc) was deduced from the dependence of pressure of cloud points on the concentration of surfactant AOT at constant temperature and water concentration. The results show that there are transition points on the cloud point curve in a very narrow range of concentration of surfactant AOT. The transition points were changed with the temperature and water concentration. These phenomena show that lower temperature is suitable to forming microemulsion droplet and the microemulsion with high water concentration is likely to absorb more surfactants to structure the interface.

  18. Metathesis depolymerizable surfactants

    Science.gov (United States)

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

    2008-04-15

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

  19. Surfactant recovery from water using foam fractionation: Effect of temperature and added salt

    Energy Technology Data Exchange (ETDEWEB)

    Kumpabooth, K.; Osuwan, S. [Chulalongkorn Univ., Bangkok (Thailand). Petroleum and Petrochemical Coll.; Scamehorn, J.F.; Harwell, J.H. [Univ. of Oklahoma, Norman, OK (United States). Inst. for Applied Surfactant Research

    1999-01-01

    The purpose of this study was to investigate the use of foam fractionation to recover surfactant present at low concentrations in aqueous streams. A simple continuous mode foam fractionation was used, and three surfactants were chosen for this study: sodium dodecyl sulfate, cetylpyridinium chloride, and sodium n-hexadecyl diphenyloxide disulfonate. In a previous study the effects of surfactant concentration, air flow rate, liquid- and vapor-phase heights, and sparger type were investigated for these surfactants. Here, the effects of temperature and added salt are studied. It is found that the foam flow rate and enrichment ratio increase whereas the foam wetness and the rate of surfactant recovery decrease with increasing temperature. Increasing the concentration of added salt decreases the CMC of the surfactants. The foam flow rate, foam wetness, and the rate of surfactant recovery increase, while the enrichment ratio decreases with increasing concentration of salt.

  20. Formation of surfactant-laden drops: comparison of experimental and numerical results

    Science.gov (United States)

    Kovalchuk, Nina; Kahouadji, Lyes; Simmons, Mark; Craster, Richard; Matar, Omar; Juric, Damir; Chergui, Jalel; Shin, Seungwon

    2016-11-01

    Drop formation is ubiquitous in many industrial processes, with surfactants being commonly used to stabilise drops. Thus, understanding the regularities of drop formation and accompanying processes, such as formation of satellite droplets in the presence of surfactant is of high importance. Here we present the results of a comparative experimental and numerical study on formation of surfactant-laden drops over a range of flow rates and surfactant concentrations. The precise parameters of the surface tension isotherm for surfactants used in the experimental study are implemented in the numerical code enabling quantitative comparison between the two approaches. It is shown that the effect of surfactant depends not only on concentration, but also on the value of critical micellar concentration (cmc). The transition to the regime where satellite droplets are no longer released was observed when the flow rate exceeded a threshold value depending on surfactant concentration and cmc value. EPSRC UK Programme Grant MEMPHIS (EP/K003976/1).

  1. Lipid Bilayers in the Gel Phase Become Saturated by Triton X-100 at Lower Surfactant Concentrations Than Those in the Fluid Phase

    Science.gov (United States)

    Ahyayauch, Hasna; Collado, M. Isabel; Alonso, Alicia; Goñi, Felix M.

    2012-01-01

    It has been repeatedly observed that lipid bilayers in the gel phase are solubilized by lower concentrations of Triton X-100, at least within certain temperature ranges, or other nonionic detergents than bilayers in the fluid phase. In a previous study, we showed that detergent partition coefficients into the lipid bilayer were the same for the gel and the fluid phases. In this contribution, turbidity, calorimetry, and 31P-NMR concur in showing that bilayers in the gel state (at least down to 13–20°C below the gel-fluid transition temperature) become saturated with detergent at lower detergent concentrations than those in the fluid state, irrespective of temperature. The different saturation may explain the observed differences in solubilization. PMID:22713566

  2. NUMERICAL SIMULATION AND FIELD IMPLEMENTATION OF SURFACTANT FLOODING

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on the features of surfactant flooding, a mathematical model for surfactant flooding is established. The adsorption-retention, convection diffusion of surfactant and influence of concentration change upon relative permeability curve are included in the model. The novel description of adsorption quantity of surfactant and relative permeability curve are presented, which enhance the coincidence between mathematical model and field practice, the relative errors of main development indexes are within 6%. The model is applied to the numerical research of the surfactant flooding in the untabulated beds of Xing1-3 surfactant flooding pilot site of No.4 Oil Production Company of Daqing Oilfield, the influences of surfactant concentration, injection quantity, slug combination mode upon the development effect and economic benefit are quantitatively analyzed, the injection scheme is optimized as follows: surfactant concentration is 0.5%, slug volume is 0.02 PV, slug combination mode is 2 slugs. After the implementation of scheme in oilfield, the cumulative increase of oil is 2186.0 t, up to nearly 30%.

  3. Analytic heuristics for a fast DSC-MRI

    Science.gov (United States)

    Virgulin, M.; Castellaro, M.; Marcuzzi, F.; Grisan, E.

    2014-03-01

    Hemodynamics of the human brain may be studied with Dynamic Susceptibility Contrast MRI (DSC-MRI) imaging. The sequence of volumes obtained exhibits a strong spatiotemporal correlation, that can be exploited to predict which measurements will bring mostly the new information contained in the next frames. In general, the sampling speed is an important issue in many applications of the MRI, so that the focus of many current researches is to study methods to reduce the number of measurement samples needed for each frame without degrading the image quality. For the DSC-MRI, the frequency under-sampling of single frame can be exploited to make more frequent space or time acquisitions, thus increasing the time resolution and allowing the analysis of fast dynamics not yet observed. Generally (and also for MRI), the recovery of sparse signals has been achieved by Compressed Sensing (CS) techniques, which are based on statistical properties rather than deterministic ones.. By studying analytically the compound Fourier+Wavelet transform, involved in the processes of reconstruction and sparsification of MR images, we propose a deterministic technique for a rapid-MRI, exploiting the relations between the wavelet sparse representation of the recovered and the frequency samples. We give results on real images and on artificial phantoms with added noise, showing the superiority of the methods both with respect to classical Iterative Hard Thresholding (IHT) and to Location Constraint Approximate Message Passing (LCAMP) reconstruction algorithms.

  4. Profiles in Leadership: Clifton J. Latiolais, MSc, DSc.

    Science.gov (United States)

    White, Sara; Godwin, Harold N; Weber, Robert J

    2013-09-01

    The Director's Forum series is designed to guide pharmacy leaders in establishing patient-centered services in hospitals and health systems. August 2013 marks the 50th anniversary of the publication of the Mirror to Hospital Pharmacy, which was a comprehensive study of pharmacy services in the United States. The late Clifton J. Latiolais, MS, DSc, served as the assistant program director for the study and was a co-author of the Mirror. The late Don E. Francke, MS, DSc, was the lead author of the Mirror and the principal investigator of the federally funded study that reviewed hospital pharmacy services across the United States. The next 2 articles in Director's Forum profile the leadership of Drs. Latiolais and Francke. This article highlights Dr. Latiolais ("Clif") by briefly reviewing his biography and key career accomplishments, describing his leadership philosophy, and translating that philosophy to today's health care challenges. Clif's influence on health system pharmacy serves as an example of effective leadership. This historical perspective on Clif's leadership, as seen through the eyes of those who knew him, provides directors of pharmacy a valuable leadership viewpoint as they develop strategies to enhance patient-centered pharmacy services.

  5. Study on biodegradation process of lignin by FTIR and DSC.

    Science.gov (United States)

    Liu, Yang; Hu, Tianjue; Wu, Zhengping; Zeng, Guangming; Huang, Danlian; Shen, Ying; He, Xiaoxiao; Lai, Mingyong; He, Yibin

    2014-12-01

    The biodegradation process of lignin by Penicillium simplicissimum was studied to reveal the lignin biodegradation mechanisms. The biodegradation products of lignin were detected using Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, different scanning calorimeter (DSC), and stereoscopic microscope. The analysis of FTIR spectrum showed the cleavage of various ether linkages (1,365 and 1,110 cm(-1)), oxidation, and demethylation (2,847 cm(-1)) by comparing the different peak values in the corresponding curve of each sample. Moreover, the differences (Tm and ΔHm values) between the DSC curves indirectly verified the FTIR analysis of biodegradation process. In addition, the effects of adding hydrogen peroxide (H2O2) to lignin biodegradation process were analyzed, which indicated that H2O2 could accelerate the secretion of the MnP and LiP and improve the enzymes activity. What is more, lignin peroxidase and manganese peroxidase catalyzed the lignin degradation effectively only when H2O2 was presented.

  6. Reticulation of Aqueous Polyurethane Systems Controlled by DSC Method

    Directory of Open Access Journals (Sweden)

    Jakov Stamenkovic

    2006-06-01

    Full Text Available The DSC method has been employed to monitor the kinetics of reticulation ofaqueous polyurethane systems without catalysts, and with the commercial catalyst of zirconium(CAT®XC-6212 and the highly selective manganese catalyst, the complex Mn(III-diacetylacetonemaleinate (MAM. Among the polyol components, the acrylic emulsions wereused for reticulation in this research, and as suitable reticulation agents the water emulsiblealiphatic polyisocyanates based on hexamethylendoisocyanate with the different contents ofNCO-groups were employed. On the basis of DSC analysis, applying the methods of Kissinger,Freeman-Carroll and Crane-Ellerstein the pseudo kinetic parameters of the reticulation reactionof aqueous systems were determined. The temperature of the examination ranged from 50oC to450oC with the heat rate of 0.5oC/min. The reduction of the activation energy and the increaseof the standard deviation indicate the catalytic action of the selective catalysts of zirconium andmanganese. The impact of the catalysts on the reduction of the activation energy is thestrongest when using the catalysts of manganese and applying all the three afore-said methods.The least aberrations among the stated methods in defining the kinetic parameters wereobtained by using the manganese catalyst.

  7. Phosphine oxide surfactants revisited.

    Science.gov (United States)

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

    2016-04-01

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

  8. 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.

  9. Modeling transport effects of perfluorinated and hydrocarbon surfactants in groundwater by using micellar liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Rashad N. [Department of Chemistry and Center for Integrative Toxicology, Michigan State University, East Lansing, MI 48824-1322 (United States); McGuffin, Victoria L. [Department of Chemistry and Center for Integrative Toxicology, Michigan State University, East Lansing, MI 48824-1322 (United States)], E-mail: jgshabus@aol.com

    2007-11-05

    The effects of hydrocarbon and perfluorinated surfactants, above their critical micelle concentration (CMC), on the transport of neutral environmental pollutants are compared. Reversed-phase micellar liquid chromatography is used to model the groundwater system. The octadecylsilica stationary phase serves to simulate soil particles containing organic matter, whereas the aqueous surfactant mobile phases serve to simulate groundwater containing a surfactant at varying concentrations. Sodium dodecyl sulfate and lithium perfluorooctane sulfonate are used as representatives of the hydrocarbon and perfluorinated surfactants, respectively. Benzene, mono- and perhalogenated benzenes, and polycyclic aromatic hydrocarbons are used as models for environmental pollutants. Transport effects were elucidated from the retention factor, k, and the equilibrium constant per micelle, K{sub eq}, of the model pollutants in the individual surfactants. Based on k values, the transport of the model pollutants increased in both surfactant solutions in comparison to pure water. As the concentration of the surfactants increased, the transport of the pollutants increased as well. Notably, the K{sub eq} values of the pollutants in the perfluorinated surfactant were at least an order of magnitude less than those in the hydrocarbon surfactant. Overall, these results suggest that the presence of a perfluorinated surfactant, above its CMC, increases the transport of pollutants in a groundwater system. However, the perfluorinated surfactant exhibits a lesser transport effect than the hydrocarbon surfactant.

  10. Rheology of cellulose nanofibrils in the presence of surfactants.

    Science.gov (United States)

    Quennouz, Nawal; Hashmi, Sara M; Choi, Hong Sung; Kim, Jin Woong; Osuji, Chinedum O

    2016-01-07

    Cellulose nanofibrils (CNFs) present unique opportunities for rheology modification in complex fluids. Here we systematically consider the effect of ionic and non-ionic surfactants on the rheology of dilute CNF suspensions. Neat suspensions are transparent yield-stress fluids which display strong shear thinning and power-law dependence of modulus on concentration, G' ∼ c(2.1). Surfactant addition below a critical mass concentration cc produces an increase in the gel modulus with retention of optical clarity. Larger than critical concentrations induce significant fibril aggregation leading to the loss of suspension stability and optical clarity, and to aggregate sedimentation. The critical concentration was the lowest for a cationic surfactant (DTAB), cc ≈ 0.08%, while suspension stability was retained for non-ionic surfactants (Pluronic F68, TX100) at concentrations up to 8%. The anionic surfactant SDS led to a loss of stability at cc ≈ 1.6% whereas suspension stability was not compromised by anionic SLES up to 8%. Dynamic light scattering data are consistent with a scenario in which gel formation is driven by micelle-nanofibril bridging mediated by associative interactions of ethoxylated surfactant headgroups with the cellulose fibrils. This may explain the strong difference between the properties of SDS and SLES-modified suspensions. These results have implications for the use of CNFs as a rheology modifier in surfactant-containing systems.

  11. Characterization and control of surfactant-mediated Norovirus interactions.

    Science.gov (United States)

    Mertens, Brittany S; Velev, Orlin D

    2015-11-28

    Understanding of the colloidal interactions of Norovirus particles in aqueous medium could provide insights on the origins of the notorious stability and infectivity of these widespread viral agents. We characterized the effects of solution pH and surfactant type and concentration on the aggregation, dispersion, and disassembly of Norovirus virus-like particles (VLPs) using dynamic light scattering, electrophoretic light scattering, and transmission electron microscopy. Owing to net negative surface charge of the VLPs at neutral pH, low concentrations of cationic surfactant tend to aggregate the VLPs, whereas low concentrations of anionic surfactant tend to disperse the particles. Increasing the concentration of these surfactants beyond their critical micelle concentration leads to virus capsid disassembly and breakdown of aggregates. Non-ionic surfactants, however, had little effect on virus interactions and likely stabilized them additionally in suspension. The data were interpreted on the basis of simple models for surfactant binding and re-charging of the virus capsid. We used zeta potential data to characterize virus surface charge and interpret the mechanisms behind these demonstrated surfactant-virus interactions. The fundamental understanding and control of these interactions will aid in practical formulations for virus inactivation and removal from contaminated surfaces.

  12. Perfluorinated Alcohols Induce Complex Coacervation in Mixed Surfactants.

    Science.gov (United States)

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

    2016-03-15

    Recently, we reported a unique and nearly ubiquitous phenomenon of inducing simple and complex coacervation in solutions of a broad variety of individual and mixed amphiphiles and over a wide range of concentrations and mole fractions. This paper describes a novel type of biphasic separation in aqueous solutions of mixed cationic-anionic (catanionic) surfactants induced by hexafluoroisopropanol (HFIP). The test cases included mixtures of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) (surfactants with different carbon chain lengths) as well as dodecyltrimethylammonium bromide (DTAB) with SDS (surfactants with the same carbon chain lengths). The CTAB-SDS-HFIP coacervate systems can be produced at many different mole ratios of surfactant, but DTAB-SDS-HFIP formed only coacervates at equimolar (1:1) mole ratios of DTAB and SDS. The phase-transition behavior of both systems was studied over a wide range of surfactant and HFIP concentrations at the stoichiometric (1:1) mole ratio of cationic/anionic surfactants. The chemical compositions of each of the two phases (aqueous-rich and coacervate phases) were studied with regard to the concentrations of HFIP, water, and individual surfactants. It is revealed that the surfactant-rich phase (coacervate phase) contains a large percentage of fluoroalcohol relative to the aqueous phase and is enriched in both surfactants but contains a small percentage of water. Surprisingly, the concentration of water in the coacervate phase increases as the total HFIP concentration is increased while the concentration of HFIP in the coacervate phase remains relatively constant, which means a larger amount of water associated with HFIP molecules is extracted into the coacervate phase, which results in the growth of the phase. The volume of the coacervate phase increases with an increase in surfactant concentration and total HFIP %. The coacervate phase is highly enriched in the two amphiphilic ions (DTA(+) and DS

  13. Overriding "doing wrong" and "not doing right": validation of the Dispositional Self-Control Scale (DSC).

    Science.gov (United States)

    Ein-Gar, Danit; Sagiv, Lilach

    2014-01-01

    We present the Dispositional Self-Control (DSC) Scale, which reflects individuals' tendency to override 2 types of temptations, termed doing wrong and not doing right. We report a series of 5 studies designed to test the reliability and validity of the scale. As hypothesized, high DSC predicts distant future orientation and low DSC predicts deviant behaviors such as aggression, alcohol misuse, and aberrant driving. DSC also predicts task performance among resource-depleted participants. Taken together, these findings suggest that the DSC Scale could be a useful tool toward further understanding the role of personality in overcoming self-control challenges.

  14. 自我增值这选:Sony DSC-F717

    Institute of Scientific and Technical Information of China (English)

    高飞

    2002-01-01

    近年的10月都是Sony推出旗舰级数码相机的日子,2000年的DSC-505v、2001年的DSC-F707,2002年有这部终极强化版的DSC-F717。改用回DSC-F505银色机身的F717,外形与DSC-F707无甚分别。不过,在机能上则作出了自我增值!

  15. Effects of alkyl polyglycoside, a nonionic surfactant, and forage-to-concentrate ratio on rumen fermentation, amino acid composition of rumen content, bacteria and plasma in goats.

    Science.gov (United States)

    Zeng, Bo; Tan, Zhiliang; Tang, Shaoxun; Han, Xuefeng; Tan, Chuanyan; Zhong, Rongzhen; Hea, Zhixiong; Arigbede, Oluwasanmi Moses

    2011-06-01

    In the present study, the effects of different forage-to-concentrate ratios (F:C) and an alkyl polyglycoside (APG) supplementation on parameters of rumen and blood metabolism were investigated in goats. A 2 x 2 factorial experiment was arranged within a 4 x 4 Latin square design (four 22-day periods), using four wether goats equipped with permanent ruminal cannulas. The experimental diets included two F:C levels (40:60 vs. 60:40), and two APG supplementation levels (None or 13 ml APG daily per animal). Rumen contents and blood samples were collected at the end of each period. Dietary F:C alteration affected plasma urea and influenced the proportions of leucine, histidine, arginine, glycine, proline, alanine, valine, phenylalanine, cysteine and tyrosine in rumen content, and the proportions of methionine, threonine and proline in solid-associated bacteria (SAB) significantly. Dietary APG decreased the proportions of valine and phenylalanine in rumen content, and the histidine content of liquid-associated bacteria. The interaction between dietary F:C and APG was significant for the proportions of glycine and alanine in rumen content, and the proportions of lysine and threonine in SAB. The proportion of lysine was greater, but the proportion of threonine was less in SAB for goats fed high F:C diet without APG supplementation. The proportions of plasma free amino acids and glucose concentration were not affected by experimental treatments. These results indicated that dietary APG addition affected the amino acid composition of the rumen content and ruminal bacteria, but this depended on the dietary F:C ratio. It is necessary to validate the effectiveness of dietary APG supplementation in further studies with more animals.

  16. Hydrogels of sodium alginate in cationic surfactants: Surfactant dependent modulation of encapsulation/release toward Ibuprofen.

    Science.gov (United States)

    Jabeen, Suraya; Chat, Oyais Ahmad; Maswal, Masrat; Ashraf, Uzma; Rather, Ghulam Mohammad; Dar, Aijaz Ahmad

    2015-11-20

    The interaction of cetyltrimethylammoium bromide (CTAB) and its gemini homologue (butanediyl-1,4-bis (dimethylcetylammonium bromide), 16-4-16 with biocompatible polymer sodium alginate (SA) has been investigated in aqueous medium. Addition of K2CO3 influences viscoelastic properties of surfactant impregnated SA via competition between electrostatic and hydrophobic interactions. Viscosity of these polymer-surfactant systems increases with increase in concentration of K2CO3, and a cryogel is formed at about 0.5M K2CO3 concentration. The thermal stability of gel (5% SA+0.5M K2CO3) decreases with increase in surfactant concentration, a minimum is observed with increase in 16-4-16 concentration. The impact of surfactant addition on the alginate structure vis-à-vis its drug loading capability and release thereof was studied using Ibuprofen (IBU) as the model drug. The hydrogel with 16-4-16 exhibits higher IBU encapsulation and faster release in comparison to the one containing CTAB. This higher encapsulation-cum-faster release capability has been related to micelle mediated solubilization and greater porosity of the hydrogel with gemini surfactant.

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

    Energy Technology Data Exchange (ETDEWEB)

    Batigoec, Cigdem [Department of Chemistry, Faculty of Sciences, Trakya University, 22030 Edirne (Turkey); Akbas, Halide, E-mail: hakbas34@yahoo.com [Department of Chemistry, Faculty of Sciences, Trakya University, 22030 Edirne (Turkey); Boz, Mesut [Department of Chemistry, Faculty of Sciences, Trakya University, 22030 Edirne (Turkey)

    2011-12-15

    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 {Delta}G{sub cp}{sup 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-{alpha}-{omega}-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{sub 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 ({Delta}G{sub cp}{sup 0}), the enthalpy ({Delta}H{sub cp}{sup 0}) and the entropy ({Delta}S{sub cp}{sup 0}) of the clouding phenomenon were found positive in all cases. The standard free energy ({Delta}G{sub cp}{sup 0}) increased with increasing hydrophobic alkyl chain for both gemini and conventional cationic

  18. Determination of the oxidative stability by DSC of vegetable oils from the Amazonian area.

    Science.gov (United States)

    Pardauil, Juliana J R; Souza, Luiz K C; Molfetta, Fábio A; Zamian, José R; Rocha Filho, Geraldo N; da Costa, C E F

    2011-05-01

    Differential scanning calorimetry (DSC) and a Rancimat method apparatus were applied to evaluate the oxidative stability of buriti pulp oil (Mauritia flexuosa Mart), rubber seed oil (Hevea brasiliensis), and passion fruit oil (Passiflora edulis). The Rancimat measurements taken for the oxidative induction times were performed under isothermal conditions at 100°C and in an air atmosphere. The DSC technique involved the oxidation of oil samples in an oxygen-flow DSC cell. The DSC cell temperature was set at five different isothermal temperatures: 100, 110, 120, 130 and 140°C. During the oxidation reaction, an increase in heat was observed as a sharp exothermic curve. The value T(0) represents the oxidative induction time, which is determined from the downward extrapolated DSC oxidative curve verses the time axis. These curves indicate a good correlation between the DSC T(0) and oxidative stability index (OSI) values. The DSC method is useful because it consumes less time and less sample.

  19. Multivariate statistical analysis treatment of DSC thermal properties for animal fat adulteration.

    Science.gov (United States)

    Dahimi, Omar; Rahim, Alina Abdul; Abdulkarim, S M; Hassan, Mohd Sukri; Hashari, Shazamawati B T Zam; Mashitoh, A Siti; Saadi, Sami

    2014-09-01

    The adulteration of edible fats is a kind of fraud that impairs the physical and chemical features of the original lipid materials. It has been detected in various food, pharmaceutical and cosmeceutical products. Differential scanning calorimetry (DSC) is the robust thermo-analytical machine that permits to fingerprint the primary crystallisation of triacylglycerols (TAGs) molecules and their transition behaviours. The aims of this study was to assess the cross-contamination caused by lard concentration of 0.5-5% in the mixture systems containing beef tallow (BT) and chicken fat (CF) separately. TAGs species of pure and adulterated lipids in relation to their crystallisation and melting parameters were studied using principal components analysis (PCA). The results showed that by using the heating profiles the discrimination of LD from BT and CF was very clear even at low dose of less than 1%. Same observation was depicted from the crystallisation profiles of BT adulterated by LD doses ranging from 0.1% to 1% and from 2% to 5%, respectively. Furthermore, CF adulterated with LD did not exhibit clear changes on its crystallisation profiles. Consequently, DSC coupled with PCA is one of the techniques that might use to monitor and differentiate the minimum adulteration levels caused by LD in different animal fats.

  20. Thermal stability of the DSC ruthenium dye C106 in robust electrolytes

    DEFF Research Database (Denmark)

    Lund, Torben; Phuong, Nguyen Tuyet; Pechy, Peter

    2014-01-01

    the dye from the TiO2 particles and analyzed its by HPLC coupled to UV/Vis and electro spray mass spectrometry. Samples prepared in the glove box gave the highest stability with a steady state photo anode surface concentration of 80% C106 intact and the remaining ∼20% being the N-butylbenzimidazole (NBB......We have investigated the thermal stability of the heteroleptic ruthenium complex C106 employed as a sensitizer in dye-sensitized solar cells. The C106 was adsorbed on TiO2 particles and exposed to 2 different iodide/triidode based redox electrolytes A and B at 80 °C for up to 1500 h in sealed glass...... of the degree of dye loading of the TiO2 particles and the ratio between the amount of dyed TiO2 particles and electrolyte volume. Assuming that this substitution is the predominant loss mechanism in a DSC during thermal stress, we estimate the reduction in the DSC efficiency after long term heat to be 12...

  1. 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.

  2. Removal of 226Ra and 228Ra from TENORM sludge waste using surfactants solutions.

    Science.gov (United States)

    Attallah, M F; Hamed, Mostafa M; El Afifi, E M; Aly, H F

    2015-01-01

    The feasibility of using surfactants as extracting agent for the removal of radium species from TENORM sludge produced from petroleum industry is evaluated. In this investigation cationic and nonionic surfactants were used as extracting agents for the removal of radium radionuclides from the sludge waste. Two surfactants namely cetyltrimethylammonium bromide (CTAB) and Triton X-100 (TX100) were investigated as the extracting agents. Different parameters affecting the removal of both (226)Ra and (228)Ra by the two surfactants as well as their admixture were studied by the batch technique. These parameters include effect of shaking time, surfactants concentration and temperature as well as the effect of surfactants admixture. It was found that, higher solution temperature improves the removal efficiency of radium species. Combined extraction of nonionic and cationic surfactants produces synergistic effect in removal both (226)Ra and (228)Ra, where the removals reached 84% and 80% for (226)Ra and (228)Ra, respectively, were obtained using surfactants admixture.

  3. Conformational and phase transitions in DNA--photosensitive surfactant solutions: Experiment and modeling.

    Science.gov (United States)

    Kasyanenko, N; Lysyakova, L; Ramazanov, R; Nesterenko, A; Yaroshevich, I; Titov, E; Alexeev, G; Lezov, A; Unksov, I

    2015-02-01

    DNA binding to trans- and cis-isomers of azobenzene containing cationic surfactant in 5 mM NaCl solution was investigated by the methods of dynamic light scattering (DLS), low-gradient viscometry (LGV), atomic force microscopy (AFM), circular dichroism (CD), gel electrophoresis (GE), flow birefringence (FB), UV-Vis spectrophotometry. Light-responsive conformational transitions of DNA in complex with photosensitive surfactant, changes in DNA optical anisotropy and persistent length, phase transition of DNA into nanoparticles induced by high surfactant concentration, as well as transformation of surfactant conformation under its binding to macromolecule were studied. Computer simulations of micelles formation for cis- and trans-isomers of azobenzene containing surfactant, as well as DNA-surfactant interaction, were carried out. Phase diagram for DNA-surfactant solutions was designed. The possibility to reverse the DNA packaging induced by surfactant binding with the dilution and light irradiation was shown.

  4. Surfactants in atmospheric aerosols and rainwater around lake ecosystem.

    Science.gov (United States)

    Razak, Intan Suraya; Latif, Mohd Talib; Jaafar, Shoffian Amin; Khan, Md Firoz; Mushrifah, Idris

    2015-04-01

    This study was conducted to determine the composition of surfactants in atmospheric aerosols and rainwater in the vicinity of Lake Chini, Malaysia. Samples of atmospheric aerosol and rainwater were collected between March and September 2011 using a high volume air sampler (HVAS) and glass bottles equipped with funnel. Colorimetric analysis was undertaken to determine the concentration of anionic surfactants as methylene blue active substances (MBAS) and cationic surfactants as disulphine blue active substances (DBAS). The water-soluble ionic compositions were determined using inductively coupled plasma mass spectrometry for cations (Na, K, Mg and Ca) and ion chromatography equipped with a conductivity detector for anions (F(-), Cl(-), NO3(-), and SO4(2-)) and the Nessler Method was used to obtain the NH4(+) concentrations. The source apportionment of MBAS and DBAS in atmospheric aerosols was identified using a combination of principal component analysis (PCA) and multiple linear regression (MLR). The results revealed that the concentrations of surfactants in atmospheric aerosols and rainwater were dominated by anionic surfactants as MBAS. The concentration of surfactants as MBAS and DBAS was dominated in fine mode compared to coarse mode aerosols. Using PCA/MLR analysis, two major sources of atmospheric surfactants to Lake Chini were identified as soil dust (75 to 93%) and biomass burning (2 to 22%).

  5. Surface tension method for determining binding constants for cyclodextrin inclusion complexes of ionic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Dharmawardana, U.R.; Christian, S.D.; Tucker, E.E.; Taylor, R.W.; Scamehorn, J.F. (Univ. of Oklahoma, Norman, OK (United States))

    1993-09-01

    A new method has been developed for determining binding constants of complexes of cyclodextrins with surface-active compounds, including water-soluble ionic surfactants. The technique requires measuring the change in surface tension caused by addition of a cyclodextrin (CD) to aqueous solutions of the surfactant; the experimental results lead directly to inferred values of the thermodynamic activity of the surfactant. Surface tension results are reported for three different surfactants sodium dodecyl sulfate (SDS), cetylpyridinium chloride (CPC), and cetyltrimethylammonium bromide (CTAB) in the presence and in the absence of added [beta]-CD. Data for CPC have been obtained at surfactant concentrations below and above the critical micelle concentration. Correlations between surface tension and surfactant activity are expressed by the Szyszkowski equation, which subsumes the Langmuir adsorption model and the Gibbs equation. It is observed that the surface tension increases monotonically as [beta]-cyclodextrin is added to ionic surfactant solutions. At concentrations of CD well in excess of the surfactant concentration, the surface tension approaches that of pure water, indicating that neither the surfactant-CD complexes nor CD itself are surface active. Binding constants are inferred from a model that incorporates the parameters of the Szyszkowski equation and mass action constants relating to the formation of micelles from monomers of the surfactant and the counterion. Evidence is given that two molecules of CD can complex the C-16 hydrocarbon chain of the cetyl surfactants. 30 refs., 5 figs., 1 tab.

  6. Effects of surfactants and salt on Henry's constant of n-hexane.

    Science.gov (United States)

    Yang, Chunping; Chen, Fayuan; Luo, Shenglian; Xie, Gengxin; Zeng, Guangming; Fan, Changzheng

    2010-03-15

    n-Hexane biological removal is intrinsically limited by its hydrophobic nature and low bioavailability. The addition of surfactants could enhance the transport of volatile organic compounds (VOCs) and change the gas-liquid equilibrium of VOCs. In this paper, the effects of four surfactants, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), tert-octylphenoxypoly-ethoxyethanol (Triton X-100), polyoxyethylene (20) sorbitan monooleate (Tween 80), and sodium nitrate on apparent Henry's constant of n-hexane in surfactant solutions were investigated. The apparent Henry's constants were significantly reduced when surfactants concentrations exceeded their critical micelle concentrations (cmc's). On a cmc basis, the anionic surfactant SDS was found to have the greatest effect on the apparent Henry's constant with CTAB succeeding, then followed by Triton X-100 and Tween 80. However, the apparent Henry's constant of n-hexane decreased even more rapidly when Triton X-100, a nonionic surfactant, was added than when the ionic surfactant of SDS or CTAB was applied under identical mass concentration and other conditions. These results suggest that Triton X-100 have the biggest solubilization of n-hexane among the four surfactants. Sodium nitrate slightly decreased the apparent Henry's constant of n-hexane in surfactant solutions, and could be considered as a cosolvent in the surfactant-(n-hexane) solution. In addition, the relationship between apparent Henry's constant and surfactant concentration was further developed.

  7. Syntheses of surfactants from oleochemical epoxides

    Directory of Open Access Journals (Sweden)

    Warwel Siegfried

    2001-01-01

    Full Text Available Sugar-based surfactants were obtained in good yields (up to 100% under mild conditions (70°C, methanol or mixtures of methanol and water by ring-opening of terminal epoxides with aminopolyols, derived from glucose. Reaction of N-methyl glucamine with epoxides from even-numbered C4-C18 alpha-olefins or from terminal unsaturated fatty acid methyl esters leads to linear products, while corresponding reactions with N-dodecyl glucamine or glucamine yield surfactants with different Y-structures. Products obtained by conversion of omega-epoxy fatty acid methyl esters were saponificated with NaOH or hydrolyzed enzymatically to sodium salts or free acids respectively, which are amphoteric surfactants. Studies of the surfactants at different pH-values demonstrate different surface active properties in aqueous solutions. Critical micelle concentrations (c.m.c. in a range between 2 and 500mg/l and surface tensions of 25-40mN/m were measured for several of the synthesized sugar-based surfactants. The ring-opening products are rather poor foamers, whereas some of the corresponding hydrobromides show good foaming properties.

  8. 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

  9. Surfactant studies for bench-scale operation

    Science.gov (United States)

    Hickey, Gregory S.; Sharma, Pramod K.

    1993-01-01

    A phase 2 study has been initiated to investigate surfactant-assisted coal liquefaction, with the objective of quantifying the enhancement in liquid yields and product quality. This report covers the second quarter of work. The major accomplishments were: completion of coal liquefaction autoclave reactor runs with Illinois number 6 coal at processing temperatures of 300, 325, and 350 C, and pressures of 1800 psig; analysis of the filter cake and the filtrate obtained from the treated slurry in each run; and correlation of the coal conversions and the liquid yield quality to the surfactant concentration. An increase in coal conversions and upgrading of the liquid product quality due to surfactant addition was observed for all runs.

  10. DSC analysis of irradiated proteins from Crotalus durissus terrificus

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Karina Corleto de; Silva, Monica Nascimento da; Goncalves, Karina de Oliveira; Spencer, Patrick Jack; Nascimento, Nanci do [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Full text: Snake bites are a serious public health problem, especially in subtropical countries. In Brazil, the serum, the only effective treatment in case of snake bites, is produced in horses which, despite the large size, have a reduced lifespan due to the high toxicity of the antigen. It is known that ionizing radiation effects - direct and indirect - can modify the molecular structure, affecting the biological properties of proteins. Ionizing radiation has been employed to attenuate the toxicity of snake venoms, aiming to generate an improved antigen with low toxicity. Two proteins, purified from Crotalus durissus terrificus (Cdt) venom were tested in this work: crotoxin and crotamine. Crotoxin, the main toxic compound of Cdt venom, is a heterodimeric protein composed of two subunits: crotapotin and phospholipase A2. Crotamine is a highly basic polypeptide (pI - 10.3), with myotoxic activity and molecular weight of 4882 Da. It is composed of 42 amino acids residues and reticulated by three disulfide bonds. This study aimed to investigate the effects of radiation on crotoxin and crotamine using Differential Scanning Calorimetry (DSC). After isolation of the toxins by chromatographic techniques, they were irradiated with 2.0 kGy from {sup 60}Co source. The thermodynamics analysis, carried out in a METTLER TOLEDO, DSC 822e calorimeter, showed that irradiation promoted changes of the calorimetric profile. These changes suggest that, although radiation induced structural modifications of the protein, denaturation was only partial, since transition states could still be detected, suggesting that some structural elements were still present after irradiation. Taken together, our data suggest that following irradiation, the molecules underwent conformational changes, and that the remaining structural elements displayed a lower enthalpy, clearly indicating that the previously described loss of toxicity of irradiated toxins can be mostly ascribed to structural changes

  11. Synthesis and properties of novel gemini surfactant with short spacer

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Cationic gemini surfactant dimethylene-1,2-bis(dodecyldiethylammonium bromide), referred to as C12C2C12(Et) was synthesized, and its surface property and aggregation behavior in aqueous solution were studied. The value of γat the critical micelle concentration (γcmc) is much smaller than that of the surfactant homologues with longer spacer. Spherical and elongated micelles were formed in the aqueous solution of this gemini surfactant,and the spherical micelles were absolutely dominant compared to the elongated micelles at our studied concentration quantitatively.

  12. Use of surfactants to control island size and density

    Energy Technology Data Exchange (ETDEWEB)

    Merrell, Jason; Liu, Feng; Stringfellow, Gerald B.

    2017-08-15

    Methods of controlling island size and density on an OMVPE growth film may comprise adding a surfactant at a critical concentration level, allowing a growth phase for a first period of time, and ending the growth phase when desired island size and density are achieved. For example, the island size and density of an OMVPE grown InGaN thin film may be controlled by adding an antimony surfactant at a critical concentration level.

  13. Use of a surfactant coacervate phase to extract trichloroethylene from water

    Energy Technology Data Exchange (ETDEWEB)

    Kimchuwanit, W.W.; Scamehorn, J.F.; Osuwan, S. [Univ. of Oklahoma, Norman, OK (United States)] [and others

    1996-10-01

    At temperatures above the cloud point, aqueous nonionic surfactant solutions can separate into two phases: a surfactant-rich coacervate phase and a surfactant-dilute phase. Since the coacervate phase can be a concentrated micellar solution, organic solute tends to concentrate in the coacervate due to solubilization. In this study, up to 90% of trichloroethylene was shown to be extracted into the coacervate phase in one stage. Increasing temperature, surfactant concentration, and added NaCl concentration all improved the fraction of TCE extracted.

  14. Surfactant-Amino Acid and Surfactant-Surfactant Interactions in Aqueous Medium: a Review.

    Science.gov (United States)

    Malik, Nisar Ahmad

    2015-08-01

    An overview of surfactant-amino acid interactions mainly in aqueous medium has been discussed. Main emphasis has been on the solution thermodynamics and solute-solvent interactions. Almost all available data on the topic has been presented in a lucid and simple way. Conventional surfactants have been discussed as amphiphiles forming micelles and amino acids as additives and their effect on the various physicochemical properties of these conventional surfactants. Surfactant-surfactant interactions in aqueous medium, various mixed surfactant models, are also highlighted to assess their interactions in aqueous medium. Finally, their applied part has been taken into consideration to interpret their possible uses.

  15. Surfactant Effects on Microemulsion-Based Nanoparticle Synthesis

    Directory of Open Access Journals (Sweden)

    Concha Tojo

    2010-12-01

    Full Text Available The effect of the surfactant on the size, polydispersity, type of size distribution and structure of nanoparticles synthesized in microemulsions has been studied by computer simulation. The model simulates the surfactant by means of two parameters: the intermicellar exchange parameter, kex, related to dimer life time, and film flexibility parameter, f, related to interdroplet channel size. One can conclude that an increase in surfactant flexibility leads to bigger and polydisperse nanoparticle sizes. In addition, at high concentrations, the same reaction gives rise to a unimodal distribution using a flexible surfactant, and a bimodal distribution using a rigid one. In relation to bimetallic nanoparticles, if the nanoparticle is composed of two metals with a moderate difference in reduction potentials, increasing the surfactant flexibility modifies the nanoparticle structure, giving rise to a transition from a nanoalloy (using a rigid film to a core-shell structure (using a flexible one.

  16. Surfactant aggregation and its application to drag reduction

    Energy Technology Data Exchange (ETDEWEB)

    Harwigsson, I.

    1995-09-01

    A number of different drag-reducing (DR) surfactants: nonionics, zwitterionics and ampholytics suitable for use in both cool and hot water solution are described. These surfactants have been tested under various conditions common in district energy distribution. The surfactants described are environmentally more acceptable than the organic salts of quaternary ammonium compounds which have so far dominated as DR surfactants. The micellar phase formed in water by the surfactant system cetylpyridinium chloride/sodium salicylate has been investigated with surfactant self-diffusion (NMR) measurements and cryo-transmission electron microscopy. Results from this study support the hypothesis that worm-like micellar systems form a network before the phase boundary, when the first liquid crystalline phase formed is a bicontinuous cubic phase. A series of surfactants similar to the one used in the DR experiments has been examined in dilute solutions. Critical micellar concentration and the size of these micelles are investigated as a function of the amphiphile concentration, the pH and salt concentration. Adsorption properties on silica of zwitterionic dodecyl-N,N-dimethylammonio alkanoates, with polymethylene interchange arms of different lengths, have been investigated with an in situ ellipsometry technique. The use of two-tone frequency modulation spectroscopy as a general method for the determination of water activity has been initiated. 173 refs, 6 figs

  17. Water solubility enhancements of pyrene by single and mixed surfactant solutions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Water solubility enhancements of pyrene by both single-surfactant and mixed-surfactant solutions were compared andevaluated. The solubility of pyrene in water was greatly enhanced by each of Triton X-100 (TX100), Triton X-405 (TX405), Brij 35 and SDS, in which the water solubility enhancements increased with increasing surfactant concentrations. The extent of solubility enhancements at surfactant concentrations below the CMC is the order of TX100 > Brij 35 > TX405 > SDS; the sequence at surfactantconcentrations above the CMC is TX100 > Brij 35 > SDS > TX405. Pyrene was solubilized synergistically by anionic-nonionic mixed surfactant solutions, especially at low surfactant concentrations. The synergistic power of the mixed surfactants is SDS-TX405 > SDS-Brij 35 > SDS-TX100. The synergism as noted is attributed to increasing Kmc and/or decreasing the CMC of the mixed surfactan solution. For SDS-TX405 and SDS-Brij 35 mixed surfactant solutions, an increase in Kmc is coupled with a decrease in the CMC; for SDS-TX100, only a decreased in the CMC value is noted. Mixed-surfactant solutions may improve the performance of the surfactant-enhanced remediation (SER) of soils by increasing the bioavailability and biodegradation of non-aqueous-phase organic pollutants and reducing the level of surfactant pollution and remediation expenses.

  18. Solubilization capacity of nonionic surfactant micelles exhibiting strong influence on export of intracellular pigments in Monascus fermentation

    Science.gov (United States)

    Kang, Biyu; Zhang, Xuehong; Wu, Zhenqiang; Qi, Hanshi; Wang, Zhilong

    2013-01-01

    Summary In this study, perstractive fermentation of intracellular Monascus pigments in nonionic surfactant micelle aqueous solution had been studied. The permeability of cell membrane modified by nonionic surfactant might have influence on the rate of export of intracellular pigments into its extracellular broth while nearly no effect on the final extracellular pigment concentration. However, the solubilization of pigments in nonionic surfactant micelles strongly affected the final extracellular pigment concentration. The solubilization capacity of micelles depended on the kind of nonionic surfactant, the super-molecule assembly structure of nonionic surfactant in an aqueous solution, and the nonionic surfactant concentration. Elimination of pigment degradation by export of intracellular Monascus pigments and solubilizing them into nonionic surfactant micelles was also confirmed experimentally. Thus, nonionic surfactant micelle aqueous solution is potential for replacement of organic solvent for perstractive fermentation of intracellular product. PMID:23425092

  19. Solubilization capacity of nonionic surfactant micelles exhibiting strong influence on export of intracellular pigments in Monascus fermentation.

    Science.gov (United States)

    Kang, Biyu; Zhang, Xuehong; Wu, Zhenqiang; Qi, Hanshi; Wang, Zhilong

    2013-09-01

    In this study, perstractive fermentation of intracellular Monascus pigments in nonionic surfactant micelle aqueous solution had been studied. The permeability of cell membrane modified by nonionic surfactant might have influence on the rate of export of intracellular pigments into its extracellular broth while nearly no effect on the final extracellular pigment concentration. However, the solubilization of pigments in nonionic surfactant micelles strongly affected the final extracellular pigment concentration. The solubilization capacity of micelles depended on the kind of nonionic surfactant, the super-molecule assembly structure of nonionic surfactant in an aqueous solution, and the nonionic surfactant concentration. Elimination of pigment degradation by export of intracellular Monascus pigments and solubilizing them into nonionic surfactant micelles was also confirmed experimentally. Thus, nonionic surfactant micelle aqueous solution is potential for replacement of organic solvent for perstractive fermentation of intracellular product.

  20. Study of surfactant-skin interactions by skin impedance measurements.

    Science.gov (United States)

    Lu, Guojin; Moore, David J

    2012-02-01

    The stratum corneum (SC) plays a very critical physiological role as skin barrier in regulating water loss through the skin and protects the body from a wide range of physical and chemical exogenous insults. Surfactant-containing formulations can induce skin damage and irritation owing to surfactant absorption and penetration. It is generally accepted that reduction in skin barrier properties occurs only after surfactants have penetrated/permeated into the skin barrier. To mitigate the harshness of surfactant-based cleansing products, penetration/permeation of surfactants should be reduced. Skin impedance measurements have been taken in vitro on porcine skin using vertical Franz diffusion cells to investigate the impact of surfactants, temperature and pH on skin barrier integrity. These skin impedance results demonstrate excellent correlation with other published methods for assessing skin damage and irritation from different surfactant chemistry, concentration, pH, time of exposure and temperature. This study demonstrates that skin impedance can be utilized as a routine approach to screen surfactant-containing formulations for their propensity to compromise the skin barrier and hence likely lead to skin irritation.

  1. DSC and conductivity studies on PVA based proton conducting gel electrolytes

    Indian Academy of Sciences (India)

    S L Agrawal; Arvind Awadhia

    2004-12-01

    An attempt has been made in the present work to prepare polyvinyl alcohol (PVA) based proton conducting gel electrolytes in ammonium thiocyanate (NH4SCN) solution and characterize them. DSC studies affirm the formation of gels along with the presence of partial complexes. The cole–cole plots exhibit maximum ionic conductivity (2.58 × 10-3 S cm-1) for gel samples containing 6 wt% of PVA. The conductivity of gel electrolytes exhibit liquid like nature at low polymer concentrations while the behaviour is seen to be affected by the formation of PVA–NH4SCN complexes upon increase in polymer content beyond 5 wt%. Temperature dependence of ionic conductivity exhibits VTF behaviour.

  2. Mechanisms for lowering of interfacial tension in alkali/acidic oil systems; Effect of added surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Rudin, J. Wasan, D.T. (Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical Engineering)

    1992-08-01

    This paper reports that experimental studies are conducted in order to determine the physicochemical mechanism responsible for lowering of interfacial tension in alkali, surfactant, and surfactant-enhanced alkali/acidic oil systems. A well-defined model oil is chosen to examine the influence of various surfactants and surfactant mixtures, such as oleic acid and its ionic counterpart, sodium dodecyl sulfate, petroleum sulfonate, and isobutanol, on equilibrium interfacial tension. With added surfactant alone, the interfacial tension goes through an ultralow minimum with increasing acid concentration. This proves for the first time that the un-ionized acid species plays a major role in affecting interfacial tension, and the ionized acid species.

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

    Directory of Open Access Journals (Sweden)

    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.

  4. STRUCTURAL CHARACTERIZATION OF POLYETHYLENES BY DSC ANALYSIS AFTER CRYSTALLIZATION SEGREGATION

    Institute of Scientific and Technical Information of China (English)

    Yu Ma; Mao Xu

    2000-01-01

    The molecular structure of polyethylene (PE) samples with various comonomers including propylene, 1-butene and 1-hexene was investigated by DSC and 13C-NMR techniques. The density of the samples varies from 0.948 g/cm3 to 0.917 g/cm3, and the molecular weight determined by the GPC method is in the range of 1~2 × 105. The branch point content of the samples was determined by 13C-NMR measurements and was found to be less than 20 per 1000 C atoms along the main chain. Crystallization segregation DSC technique (CSDSC) was used to characterize the branch point distribution or the segment length distribution of PEs. The crystallization segregation was performed in a successive annealing process at decreasing temperatures. The interval of two successive annealing temperatures was 6 K, and the time length of each annealing step was 2.5 h. The CSDSC results clearly indicate that all the PE samples used, including some metallocene PEs,more or less exhibit their non-uniformity in segment length distribution, and bimodal or multimodal CSDSC curves were usually observed. For quantitative characterization of the CSDSC curves and the segment length distribution two parameters,the average melting point, TmAV, and the root-mean-square deviation of melting temperature, (ATm2AV)1/2, were proposed.TmAV is corresponding to the average segment length due to branching and (ATm2AV)1/2 gives information about the width of the segment length distribution. Experimental results show that both the degree of average melting temperature depression and the width of the distribution seem to increase with increasing the branching content and are dependent on the type of comonomers. Very good reproducibility and additivity of the CSDSC method were evidenced experimentally. It was concluded that the CSDSC technique is a sensitive and convenient method for characterizing the segment length distribution of branched polyethylenes and will be of great interest in structure-property relationship

  5. Synthesis and characterization of pharmaceutical surfactant templated mesoporous silica: Its application to controlled delivery of duloxetine

    Energy Technology Data Exchange (ETDEWEB)

    Mani, Ganesh; Pushparaj, Hemalatha; Peng, Mei Mei; Muthiahpillai, Palanichamy [Department of Chemical Engineering, Hanseo University, Seosan-si 356 706 (Korea, Republic of); Udhumansha, Ubaidulla [Department of Chemical Engineering, Hanseo University, Seosan-si 356 706 (Korea, Republic of); Department of Pharmaceutics, C.L. Baid Metha College of Pharmacy, Chennai (India); Jang, Hyun Tae, E-mail: htjang@hanseo.ac.kr [Department of Chemical Engineering, Hanseo University, Seosan-si 356 706 (Korea, Republic of)

    2014-03-01

    Graphical abstract: - Highlights: • Usefulness of dual pharmaceutical surfactants in silica synthesis was evaluated. • Effects of concentration of secondary template (Tween-40) were studied. • Effects of fixed solvothermal condition on mesostructure formation were studied. • Duloxetine drug loading capability was studied. • Sustained release of duloxetine was evaluated. - Abstract: A new group of mesoporous silica nanoparticles (MSNs) were synthesized using combination pharmaceutical surfactants, Triton X-100 and Tween-40 as template and loaded with duloxetine hydrochloride (DX), for improving the sustained release of DX and patterns with high drug loading. Agglomerated spherical silica MSNs were synthesized by sol–gel and solvothermal methods. The calcined and drug loaded MSNs were characterized using X-ray diffraction (XRD), Braunner–Emmett–Teller (BET), thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), diffuse reflectance ultraviolet–visible (DRS-UV–vis) spectroscopy. MSNs with high surface area and pore volume were selected and studied for their DX loading and release. The selected MSNs can accommodate a maximum of 34% DX within it. About 90% was released at 200 h and hence, the synthesized MSNs were capable of engulfing DX and sustain its release. Further form the Ritger and Peppas, Higuchi model for mechanism drug release from all the MSN matrices follows anomalous transport or Non-Fickian diffusion with the ‘r’ and ‘n’ value 0.9 and 0.45 < n < 1, respectively. So, from this study it could be concluded that the MSNs synthesized using pharmaceutical templates were better choice of reservoir for the controlled delivery of drug which requires sustained release.

  6. Photosensitive surfactants: micellization and interaction with DNA.

    Science.gov (United States)

    Zakrevskyy, Yuriy; Roxlau, Julian; Brezesinski, Gerald; Lomadze, Nino; Santer, Svetlana

    2014-01-28

    Recently, photosensitive surfactants have re-attracted considerable attention. It has been shown that their association with oppositely charged biologically important polyelectrolytes, such as DNA or microgels, can be efficiently manipulated simply by light exposure. In this article, we investigate the self-assembly of photosensitive surfactants as well as their interactions with DNA by calorimetric and spectroscopic methods. Critical micelle concentration (CMC), standard micellization enthalpy, entropy, and Gibbs energy were determined in different conditions (ionic strengths and temperatures) for a series of cationic surfactants with an azobenzene group in their tail. It is shown, that aggregation forces of photosensitive units play an important role in the micellization giving the major contribution to the micellization enthalpy. The onset of the aggregation can be traced from shift of the absorption peak position in the UV-visible spectrum. Titration UV-visible spectroscopy is used as an alternative, simple, and sensitive approach to estimate CMC. The titration UV-visible spectroscopy was also employed to investigate interactions (CAC: critical aggregation concentration, precipitation, and colloidal stabilization) in the DNA-surfactant complex.

  7. Photosensitive surfactants: Micellization and interaction with DNA

    Science.gov (United States)

    Zakrevskyy, Yuriy; Roxlau, Julian; Brezesinski, Gerald; Lomadze, Nino; Santer, Svetlana

    2014-01-01

    Recently, photosensitive surfactants have re-attracted considerable attention. It has been shown that their association with oppositely charged biologically important polyelectrolytes, such as DNA or microgels, can be efficiently manipulated simply by light exposure. In this article, we investigate the self-assembly of photosensitive surfactants as well as their interactions with DNA by calorimetric and spectroscopic methods. Critical micelle concentration (CMC), standard micellization enthalpy, entropy, and Gibbs energy were determined in different conditions (ionic strengths and temperatures) for a series of cationic surfactants with an azobenzene group in their tail. It is shown, that aggregation forces of photosensitive units play an important role in the micellization giving the major contribution to the micellization enthalpy. The onset of the aggregation can be traced from shift of the absorption peak position in the UV-visible spectrum. Titration UV-visible spectroscopy is used as an alternative, simple, and sensitive approach to estimate CMC. The titration UV-visible spectroscopy was also employed to investigate interactions (CAC: critical aggregation concentration, precipitation, and colloidal stabilization) in the DNA-surfactant complex.

  8. Optimization and mechanism of surfactant accelerating leaching test

    Institute of Scientific and Technical Information of China (English)

    艾纯明; 吴爱祥; 王贻明; 侯春来

    2016-01-01

    To solve the problem of slow leaching speed of copper, surfactant was added into lixivium as leaching agent in the experiment. Based on physical chemistry and seepage flow mechanics, the leaching mechanics of surfactant was analyzed. The solution surface tension and surfactant adsorbing on the surface of ore have a significant impact on the surface wetting effect. With leaching rate for response, the study screened out three main factors by Plackett-Burman design method: the sulfuric acid concentration, surfactant concentration and temperature. Among these three factors, the surfactant concentration is the most important contributor to leaching rate. After obtaining the experiment center by the steepest ascent experiment, a continuous variable surface model was built by response surface methodology. By solving quadratic polynomial equation, optimal conditions for leaching were finally obtained as follows:the sulfuric acid concentration was 60 g/L, the surfactant concentration was 0.00914 mol/L, and the temperature was 45 °C. The leaching rate was 66.81%in the optimized leaching conditions, which was close to the predicted value, showing that regression result was good.

  9. Dynamic surface tension of surfactant TA: experiments and theory.

    Science.gov (United States)

    Otis, D R; Ingenito, E P; Kamm, R D; Johnson, M

    1994-12-01

    A bubble surfactometer was used to measure the surface tension of an aqueous suspension of surfactant TA as a function of bubble area over a range of cycling rates and surfactant bulk concentrations. Results of the surface tension-interfacial area loops exhibited a rich variety of phenomena, the character of which varied systematically with frequency and bulk concentration. A model was developed to interpret and explain these data and for use in describing the dynamics of surface layers under more general circumstances. Surfactant was modeled as a single component with surface tension taken to depend on only the interfacial surfactant concentration. Two distinct mechanisms were considered for the exchange of surfactant between the bulk phase and interface. The first is described by a simple kinetic relationship for adsorption and desorption that pertains only when the interfacial concentration is below its maximum equilibrium value. The second mechanism is "squeeze-out" by which surfactant molecules are expelled from an interface compressed past a maximum packing state. The model provided good agreement with experimental measurements for cycling rates from 1 to 100 cycles/min and for bulk concentrations between 0.0073 and 7.3 mg/ml.

  10. 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

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

    Science.gov (United States)

    Guan, Qian; Noblitt, Scott D; Henry, Charles S

    2012-01-01

    The use of mixtures of ionic and zwitterionic surfactants in poly(dimethylsiloxane) (PDMS) microchips is reported. The effect of surfactant concentration on electroosmotic flow (EOF) was studied for a single anionic surfactant (sodium dodecyl sulfate, SDS), a single zwitterionic surfactant (N-tetradecylammonium-N,N-dimethyl-3-ammonio-1-propanesulfonate, TDAPS), and a mixed SDS/TDAPS surfactant system. SDS increased the EOF as reported previously while TDAPS showed an initial increase in EOF followed by a reduction at higher concentrations. When TDAPS was added to a solution containing SDS, the EOF decreased in a concentration-dependent manner. The EOF for all three surfactant systems followed expected pH trends, with increasing EOF at higher pH. The mixed surfactant system allowed tuning of the EOF across a range of pH and concentration conditions. After establishing the EOF behavior, the adsorption/desorption kinetics were measured and showed a slower adsorption/desorption rate for TDAPS than SDS. Finally, the separation and electrochemical detection of model catecholamines in buffer and reduced glutathione in red blood cell lysate using the mixed surfactant system were explored. The mixed surfactant system provided shorter analysis times and/or improved resolution when compared to the single surfactant systems.

  12. Sizing up surfactant synthesis.

    Science.gov (United States)

    Han, SeungHye; Mallampalli, Rama K

    2014-08-01

    Phosphatidylcholine is generated through de novo synthesis and remodeling involving a lysophospholipid. In this issue of Cell Metabolism, research from the Shimizu lab (Harayama et al., 2014) demonstrates the highly selective enzymatic behavior of lysophospholipid acyltransferases. The authors present an enzymatic model for phosphatidylcholine molecular species diversification that impacts surfactant formation.

  13. Self-consistent-field analysis of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) surfactants: micellar structure, critical micellization concentration, critical micellization temperature, and cloud point

    NARCIS (Netherlands)

    Bruijn, de V.G.; Broeke, van den L.J.P.; Leermakers, F.A.M.; Keurentjes, J.T.F.

    2002-01-01

    The self-assembly of a series of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) surfactants into spherical micelles has been analyzed by a numerical self-consistent-field model. A united atom description is used in which three segment types are identified, that is,

  14. Self-consistent-field analysis of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) surfactants: micellar structure, critical micellization concentration, critical micellization temperature, and cloud point

    NARCIS (Netherlands)

    Bruijn, de V.G.; Broeke, van den L.J.P.; Leermakers, F.A.M.; Keurentjes, J.T.F.

    2002-01-01

    The self-assembly of a series of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) surfactants into spherical micelles has been analyzed by a numerical self-consistent-field model. A united atom description is used in which three segment types are identified, that is, CH2

  15. Use of watershed factors to predict consumer surfactant toxic units in the upper Trinity river, Texas

    DEFF Research Database (Denmark)

    Johnson, David; Sanderson, Hans; Atkinson, Sam

    2009-01-01

    for surfactant loading into the environment. The objective of this project was to determine whether surfactant concentrations, expressed as toxic units, in-stream water quality, and aquatic habitat in the upper Trinity River could be predicted based on easily accessible watershed characteristics. Surface water...... surfactant concentrations were determined, and total surfactant toxic units were calculated. GIS models of geospatial, anthropogenic factors (e.g., population density) and natural factors (e.g., soil organic matter) were collected and analyzed according to subwatersheds. Multiple regression analyses using......Surfactants are high production volume chemicals that are used in a wide assortment of "down-the-drain" consumer products. Wastewater treatment plants (WWTPs) generally remove 85 to more than 99% of all surfactants from influents, but residual concentrations are discharged into receiving waters via...

  16. DSC and TMA studies on freezing and thawing gelation of galactomannan polysaccharide

    Energy Technology Data Exchange (ETDEWEB)

    Iijima, Mika, E-mail: m-iijima@nagasaki-u.ac.jp [Faculty of Education, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521 (Japan); Hatakeyama, Tatsuko [Lignocell Research, 73-8 Yatsumata, Fukui 910-3558 (Japan); Hatakeyama, Hyoe [Department of Environment and Biotechnology, Faculty of Engineering, Fukui University of Technology, 3-6-1, Gakuen, Fukui 910-8505 (Japan)

    2012-03-20

    Research highlights: Black-Right-Pointing-Pointer Locust bean gum forms hydrogels by freezing and thawing. Black-Right-Pointing-Pointer Syneresis was observed when freezing and thawing cycle (n) increased. Black-Right-Pointing-Pointer Dynamic Young's modulus increased with increasing n. Black-Right-Pointing-Pointer Non-freezing water content restrained by hydrogels decreased with increasing n. Black-Right-Pointing-Pointer Strong gel with densely packed network structure formed with increasing n. - Abstract: Among various kinds of polysaccharides known to form hydrogels, locust bean gum (LBG) consisting of a mannose backbone and galactose side chains has unique characteristics, since LBG forms hydrogels by freezing and thawing. In this study, effect of thermal history on gelation was investigated by differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). Gel/sol ratio calculated by weighing method was found to be affected by sol concentration, freezing rate and the number of freezing and thawing cycle (n). Once LBG hydrogels are formed, they are thermally stable, although syneresis was observed when n increased. Dynamic Young's modulus (E Prime ) of hydrogels measured by TMA in water increased with increasing n and decreasing freezing rate. Non-freezing water calculated from DSC melting peak of ice in the gel decreased with increasing n and decreasing freezing rate. Morphological observation of freeze-dried gels was carried out by scanning electron microscopy (SEM). The above results indicate that weak hydrogel having large molecular network structure transformed into strong gel with densely packed network structure by increasing n and decreasing freezing rate.

  17. A novel biosensor method for surfactant determination based on acetylcholinesterase inhibition

    Science.gov (United States)

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

    2012-06-01

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

  18. Research on surfactant flooding in high temperature and high-salinity reservoir for enhanced oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Ming [Southwest Petroleum Univ., Chengdu, Sichuan (China). State Key Lab. of Oil and Gas Reservoir Geology and Exploitation; Southwest Petroleum Univ., Chengdu, Sichuan (China). School of Material Science and Engineering; Zhao, Jinzhou; Yang, Yan [Southwest Petroleum Univ., Chengdu, Sichuan (China). State Key Lab. of Oil and Gas Reservoir Geology and Exploitation; Wang, Xu [Southwest Petroleum Univ., Chengdu, Sichuan (China). School of Material Science and Engineering

    2013-05-15

    The aim of this work was to research the solution properties of a new surfactant flooding system for high temperature and high salinity reservoir, which include trimeric sulfonate surfactants 1,2,3-tri(2-oxypropyl sulfonation-3-alkylether-propoxyl) propanes (TTSS-n) and anion-nonionic surfactant NPSO [sodium nonyl phenol polyethyleneoxy ether sulfonate, (EO = 10)]. The critical micelle concentrations (CMCs) of five trimeric sulfonate surfactants were smaller than 400 mg L{sup -1}. Furthermore, their interfacial tensions (IFTs) could reach an ultralow value with Tazhong 4 oil at lower concentrations. Through optimized formulation, we found that TTSS-12 had better properties and was selected as the major component of the surfactant flooding system. We designed an optimal formulation of the surfactant flooding system with 1000 mg . L{sup -1} TTSS-12 and 1000 mg . L{sup -1} NPSO surfactant. The system with a very small surfactant concentration could reach ultralow IFT with Tazhong 4 crude oils at high temperature (110 C) and high concentration formation brine (112,228.8 mg/L TDS), which proved that the simpler component surfactant had better reservoir compatibility. NPSO could weaken the disadvantage of the surfactant TTSS-12 in oil/water interface. The stability of this surfactant flooding system was evaluated by aging time, static adsorption and chromatographic separation. All experiments showed that it still keeps ultralow IFT in high temperature and high salinity conditions. Coreflooding experimentation showed that average oil recovery reached 9.8 wt% by surfactant flooding, therefore, it is feasible to use as a surfactant flooding system for enhanced oil recovery (EOR). (orig.)

  19. Structural studies of lamellar surfactant systems under shear

    DEFF Research Database (Denmark)

    Mortensen, K.

    2001-01-01

    Recent experimental studies on concentrated surfactant systems are reviewed. Particular attention is focused on the transformation from planar lamellar sheets to multilamellar vesicles. It is discussed whether both of these states are thermodynamic stable, or if the MLV is an artifact of shear...... induced factors. Recent studies includes the dependence on shear, and dependence on salt and cosurfactants, and thereby related lamellar defects. The review include moreover the demonstration that polymeric amphiphiles dramatically enhance the quality of classical surfactants. (C) 2001 Elsevier Science...

  20. 微电解法预处理高浓度阴离子表面活性剂废水%Pretreatment of wastewater containing highly concentrated anionic surfactant by micro-electrolysis

    Institute of Scientific and Technical Information of China (English)

    文善雄; 梁宝锋; 徐静; 荣树茂

    2011-01-01

    考察了不同微电解方式对含高浓度阴离子表面活性剂(AS)废水的预处理效果,结果表明,在铁炭填料分别为F3(铁屑,规格3 mm×10 mm)、C3(活性炭,规格D 2 mm×3 mm),进水pH为3.5,停留时间为30 min的相同条件下,当m(F3):m(C3)=2:1时,二元微电解法对废水AS及COD的平均去除率分别为51.32%、48.9%;当m(F3):m(Cu):m(C3)=60:60:40时,三元微电解法对废水AS及COD的平均去除率分别为54.14%、49.0%.从处理效果和实际工程应用综合考虑,选用二元微电解法预处理该废水.%The pretreatment effect of the wastewater containing highly concentrated anionic surfactant (AS) by different micro-electrolysis modes has been investigated. The results show that under the same conditions: the mass ratio of F3 (iron,size 3 mmxlO mm) and C3 (activated carbon,size D 2 mmx3 mm) is 2:1, pH 3.5 and retention time 30 min,the average removing rates of AS and COD are 51.32% and 48.9% Respectively by binary micro-electrolysis. When the mass ratio of F3、Cu and C3 is 60:60=40,the average removing rates of AS and COD are 54.14% and 49.0% Respectively by ternary micro-electrolysis. Out of consideration for the treatment effectiveness and actual application, the binary micro-electrolysis should be selected for the pretreatment of such wastewater.

  1. Physical ageing studies of poly(ethylene terephthalate) using SANS and DSC

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, Andrew [Department of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT (United Kingdom); Gordon, Duncan [Department of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT (United Kingdom); King, Stephen [ISIS Spallation Neutron Source, Rutherford-Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom); Jenkins, Mike [Department of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT (United Kingdom)]. E-mail: M.J.Jenkins@bham.ac.uk

    2006-11-15

    The process of physical ageing in a blend of deuterated and hydrogenated poly(ethylene terephalate) has been investigated using a combination of differential scanning calorimetry (DSC) and small-angle neutron scattering (SANS). The development of an endothermic peak on the glass transition has been shown using DSC. Furthermore, the radius of gyration was found to decrease during physical ageing.

  2. 47 CFR 80.359 - Frequencies for digital selective calling (DSC).

    Science.gov (United States)

    2010-10-01

    ... this incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of this... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies for digital selective calling (DSC... for digital selective calling (DSC). (a) General purpose calling. The following table describes...

  3. 7 CFR 1710.114 - TIER, DSC, OTIER and ODSC requirements.

    Science.gov (United States)

    2010-01-01

    ... substantially in their entirety are in 7 CFR 1717.155. (4) If a distribution borrower has in service or under... 7 Agriculture 11 2010-01-01 2010-01-01 false TIER, DSC, OTIER and ODSC requirements. 1710.114... AND GUARANTEES Loan Purposes and Basic Policies § 1710.114 TIER, DSC, OTIER and ODSC requirements....

  4. 47 CFR 80.103 - Digital selective calling (DSC) operating procedures.

    Science.gov (United States)

    2010-10-01

    ... accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of this standard can be inspected at the Federal... 47 Telecommunication 5 2010-10-01 2010-10-01 false Digital selective calling (DSC) operating... Procedures-General § 80.103 Digital selective calling (DSC) operating procedures. (a) Operating...

  5. Gelatinisation kinetics of corn and chickpea starches using DSC, RVA, and dynamic rheometry

    Science.gov (United States)

    The gelatinisation kinetics (non-isothermal) of corn and chickpea starches at different heating rates were calculated using differential scanning calorimetry (DSC), rapid visco analyser (RVA), and oscillatory dynamic rheometry. The data obtained from the DSC thermogram and the RVA profiles were fitt...

  6. Studies on interfacial tension and contact angle of synthesized surfactant and polymeric from castor oil for enhanced oil recovery

    Science.gov (United States)

    Babu, Keshak; Pal, Nilanjan; Bera, Achinta; Saxena, V. K.; Mandal, Ajay

    2015-10-01

    New synthesized polymeric surfactants have immensely attracted the researchers for further development of chemical enhanced oil recovery method particularly in surfactant flooding. Contact angle and interfacial tension measurement tests are the effective ways to identify proper chemicals/surfactants for enhanced oil recovery by chemical/surfactant flooding. In the present study a new polymeric surfactant was synthesized from pre-synthesized sodium methyl ester sulfonate (surfactant) and acrylamide for application in chemical enhanced oil recovery. The synthesized surfactant and polymeric surfactant were used to measure interfacial tension between their aqueous phase and crude oil phase to investigate the efficiency of the surfactants in reduction of interfacial tension. The synthesized polymeric surfactant has also ability to control the mobility because of its viscous nature in aqueous solution. Contact angles of solid-crude oil-surfactant interface were also measured to study the effect of the synthesized surfactant and polymeric surfactant on wettability alteration mechanism. Synergistic effect was studied by using NaCl and synthesized surfactants on interfacial tension. Dynamic interfacial tensions of the surfactant and polymeric surfactant solutions with crude oil were measured at different NaCl concentrations. Interfacial tension was found to be lowered up to 10-2 to 10-3 mN/m which is effective for oil recovery. Measurement of contact angle indicates the wettability change of the quartz surface. Comparative studies on efficiencies of synthesized sodium methyl ester sulfonate surfactant and polymeric surfactant were also carried out with respect to interfacial tension reduction and contact angle change.

  7. 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.

  8. Comparative study of DSC-PWI and 3D-ASL in ischemic stroke patients.

    Science.gov (United States)

    Zhang, Shui-xia; Yao, Yi-hao; Zhang, Shun; Zhu, Wen-jie; Tang, Xiang-yu; Qin, Yuan-yuan; Zhao, Ling-yun; Liu, Cheng-xia; Zhu, Wen-zhen

    2015-12-01

    The purpose of this study was to quantitatively analyze the relationship between three dimensional arterial spin labeling (3D-ASL) and dynamic susceptibility contrast-enhanced perfusion weighted imaging (DSC-PWI) in ischemic stroke patients. Thirty patients with ischemic stroke were included in this study. All subjects underwent routine magnetic resonance imaging scanning, diffusion weighted imaging (DWI), magnetic resonance angiography (MRA), 3D-ASL and DSC-PWI on a 3.0T MR scanner. Regions of interest (ROIs) were drawn on the cerebral blood flow (CBF) maps (derived from ASL) and multi-parametric DSC perfusion maps, and then, the absolute and relative values of ASL-CBF, DSC-derived CBF, and DSC-derived mean transit time (MTT) were calculated. The relationships between ASL and DSC parameters were analyzed using Pearson's correlation analysis. Receiver operative characteristic (ROC) curves were performed to define the thresholds of relative value of ASL-CBF (rASL) that could best predict DSC-CBF reduction and MTT prolongation. Relative ASL better correlated with CBF and MTT in the anterior circulation with the Pearson correlation coefficients (R) values being 0.611 (P1.0 were 75.7%, 89.2% and 87.8% respectively. ASL-CBF map has better linear correlations with DSC-derived parameters (DSC-CBF and MTT) in anterior circulation in ischemic stroke patients. Additionally, when rASL is lower than 0.585, it could predict DSC-CBF decrease with moderate accuracy. If rASL values range from 0.585 to 0.952, we just speculate the prolonged MTT.

  9. Surfactant-laden drop jellyfish-breakup mode induced by the Marangoni effect

    Science.gov (United States)

    Zhao, Hui; Zhang, Wen-Bin; Xu, Jian-Liang; Li, Wei-Feng; Liu, Hai-Feng

    2017-03-01

    Drop breakup is a familiar event in both nature and technology. In this study, we find that the bag breakup mode can be replaced by a new breakup mode: jellyfish breakup, when the surfactant concentration of a surfactant-laden drop is high. This new breakup mode has a morphology resembling a jellyfish with many long tentacles. This is due to the inhomogeneous distribution of surfactant in the process of drop deformation and breakup. The thin film of liquid can remain stable as a result of the Marangoni effect. Finally, we propose that the dimensionless surfactant concentration can serve as a criterion for breakup mechanisms.

  10. MICROBIAL SURFACTANTS. I. GLYCOLIPIDS

    Directory of Open Access Journals (Sweden)

    Pirog T. Р.

    2014-02-01

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

  11. Surfactants at the Design Limit.

    Science.gov (United States)

    Czajka, Adam; Hazell, Gavin; Eastoe, Julian

    2015-08-04

    This article analyzes how the individual structural elements of surfactant molecules affect surface properties, in particular, the point of reference defined by the limiting surface tension at the aqueous cmc, γcmc. Particular emphasis is given to how the chemical nature and structure of the hydrophobic tails influence γcmc. By comparing the three different classes of surfactants, fluorocarbon, silicone, and hydrocarbon, a generalized surface packing index is introduced which is independent of the chemical nature of the surfactants. This parameter ϕcmc represents the volume fraction of surfactant chain fragments in a surface film at the aqueous cmc. It is shown that ϕcmc is a useful index for understanding the limiting surface tension of surfactants and can be useful for designing new superefficient surfactants.

  12. Study of the interactions between lysozyme and a fully-fluorinated surfactant in aqueous solution at different surfactant-protein ratios.

    Science.gov (United States)

    Ruso, Juan M; González-Pérez, Alfredo; Prieto, Gerardo; Sarmiento, Félix

    2003-11-01

    The interactions of a fluorinated surfactant, sodium perfluorooctanoate, with lysozyme, have been investigated by a combination of UV absorbance, electrical conductivity and dynamic light scattering to detect and to characterize the conformational transitions of lysozyme. By using difference spectroscopy, the transition was followed as a function of surfactant concentration, and the data were analyzed to obtain the Gibbs energy of the transition in water (DeltaGw(o)) and in a hydrophobic environment (DeltaGh(o)) for saturated protein-surfactant complexes. Electrical conductivity was used to determine the critical micelle concentration of the surfactant in the presence of different lysozyme concentration. From these results, the average number of surfactant monomer per protein molecule was calculated. Finally, dynamic light scattering show that only changes in the secondary structure of the protein can be observed.

  13. Reversibly enhanced aqueous solubilization of volatile organic compounds using a redox-reversible surfactant

    Institute of Scientific and Technical Information of China (English)

    Yingjie Li; Senlin Tian; Hong Mo; Ping Ning

    2011-01-01

    Surfactant-enhanced remediation (SER) is an effective method for the removal of volatile organic compounds (VOCs) from contaminated soils and groundwater.To reuse the surfactant the VOCs must be separated from the surfactant solutions.The water solubility of VOCs can be enhanced using reversible surfactants with a redox-acive group,(ferrocenylmethyl)dodecyldimethylammonium bromide (Fc12) and (ferrocenylmethyl)tetradecanedimethylammonium bromide (Fc14),above and below their critical micelle concentrations (CMC) under reducing (I+) and oxidative (I2+) conditions.The CMC values of Fc12 and Fc14 in I+ are 0.94 and 0.56 mmol/L and the solubilization of toluene by Fc12 and Fc14 in I+ for toluene is higher than the solubilization achieved with sodium dodecyl sulfate,cetyltrimethylammonium bromide and Trition X-114.The solubilization capacity of the ferrocenyl surfactants for each tested VOCs ranked as follows:ethylbenzene > toluene > benzene.The solubilities of VOCs by reversible surfactant in I+ were 30% higher than those in 12+ at comparable surfactant concentrations.The effects of Fc14 concentrations on VOCs removal efficiency were as follows:benzene > toluene > ethylbenzene.However,an improved removal efficiency was achieved at low ferrocenyl surfactant concentrations.Furthermore,the reversible surfactant could be recycled through chemical approaches to remove organic pollutants,which could significantly reduce the operating costs of SER technology.

  14. Vesicle formation and stability in the surfactant sodium 4-(1'-heptylnonyl) benzenesulfonate

    Energy Technology Data Exchange (ETDEWEB)

    Franses, E.I.; Talmon, Y.; Scriven, L.E.; Davis, H.T.; Miller, W.G.

    1982-04-01

    Surfactants composed of a hydrophilic moiety covalently attached to the end of a hydrocarbon chain (e.g., sodium dodecyl sulfate), spontaneously form micelles, equilibrium aggregates, in solution if the surfactant concentration exceeds a critical value called the CMC. Naturally occurring double-tail surfactants (e.g., phospholipids) are not known to form micelles. Over a considerable range in surfactant concentration, 2 phases coexist in equilibrium: a hydrated, multilamellar (smectic) surfactant phase and an aqueous phase saturated with surfactant. In this report the preparation of vesicles, their direct, unstained visualization by electron microscopy, and investigation of their stability and structure by turbidimetry, conductimetry, light microscopy, densitometry, scanning calorimetry, and nuclear magnetic resonance spectroscopy are discussed. Dispersed liquid crystal was studied by the same means. For comparison, parallel studies on bovine lecithin are presented. From the results, it is concluded that these vesicles may be stable for many months, but eventually revert to multilamellar liquid crystals.

  15. Adsorption of surfactants and polymers at interfaces

    Science.gov (United States)

    Rojas, Orlando Jose

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

  16. Novel fluorinated gemini surfactants with γ-butyrolactone segments.

    Science.gov (United States)

    Kawase, Tokuzo; Okada, Kazuyuki; Oida, Tatsuo

    2015-01-01

    In this work, novel γ-butyrolactone-type monomeric and dimeric (gemini) surfactants with a semifluoroalkyl group [Rf- (CH2)3-; Rf = C4F9, C6F13, C8F17] as the hydrophobic group were successfully synthesized. Dimethyl malonate was dimerized or connected using Br(CH2)sBr (s = 0, 1, 2, 3) to give tetraesters, and they were bis-allylated. Radical addition of fluoroalkyl using Rf-I and an initiator, i.e., 2,2'-azobisisobutyronitrile for C4F9 or di-t-butyl peroxide for C6F13 and C8F17, was perform at high temperature, with prolonged heating, to obtain bis(semifluoroalkyl)-dilactone diesters. These dilactone diesters were hydrolyzed using KOH/EtOH followed by decarboxylation in AcOH to afford γ-butyrolactonetype gemini surfactants. Common 1 + 1 semifluoroalkyl lactone surfactants were synthesized using the same method. Their surfactant properties [critical micelle concentration (CMC), γCMC, pC20, ΓCMC, and AG] were investigated by measuring the surface tension of the γ-hydroxybutyrate form prepared in aqueous tetrabutylammonium hydroxide solution. As expected, the CMC values of the gemini surfactants were more than one order of magnitude smaller than those of the corresponding 1 + 1 surfactants. Other properties also showed the excellent ability of the gemini structure to reduce the surface tension. These surfactants were easily and quantitatively recovered by acidification. The monomeric surfactant was recovered in the γ-hydroxybutyric acid form, and the gemini surfactant as a mixture of γ-butyrolactone and γ-hydroxybutyric acid forms.

  17. Adsorption of anionic and non-ionic surfactants on carbon nanotubes in water with dissipative particle dynamics simulation.

    Science.gov (United States)

    Vo, Minh D; Shiau, Benjamin; Harwell, Jeffrey H; Papavassiliou, Dimitrios V

    2016-05-28

    The morphology of surfactants physically adsorbed on the surface of carbon nanotubes (CNTs) has a significant impact on the dispersion of CNTs in the solution. The adsorption of the surfactants alfoterra 123-8s (AF) and tergitol 15-s-40 (TG) on CNTs was investigated with dissipative particle dynamics (DPD) simulations, as well as the behavior of the binary surfactant system with CNTs. Properties of surfactants (i.e., critical micelle concentration, aggregation number, shape and size of micelle, and diffusivity) in water were determined to validate the simulation model. Results indicated that the assembly of surfactants (AF and TG) on CNTs depends on the interaction of the surfactant tail and the CNT surface, where surfactants formed mainly hemimicellar structures. For surfactants in solution, most micelles had spherical shape. The particles formed by the CNT and the adsorbed surfactant became hydrophilic, due to the outward orientation of the head groups of the surfactants that formed monolayer adsorption. In the binary surfactant system, the presence of TG on the CNT surface provided a considerable hydrophilic steric effect, due to the EO groups of TG molecules. It was also seen that the adsorption of AF was more favorable than TG on the CNT surface. Diffusion coefficients for the surfactants in the bulk and surface diffusion on the CNT were calculated. These results are applicable, in a qualitative sense, to the more general case of adsorption of surfactants on the hydrophobic surface of cylindrically shaped nanoscale objects.

  18. Adsorption of anionic and non-ionic surfactants on carbon nanotubes in water with dissipative particle dynamics simulation

    Science.gov (United States)

    Vo, Minh D.; Shiau, Benjamin; Harwell, Jeffrey H.; Papavassiliou, Dimitrios V.

    2016-05-01

    The morphology of surfactants physically adsorbed on the surface of carbon nanotubes (CNTs) has a significant impact on the dispersion of CNTs in the solution. The adsorption of the surfactants alfoterra 123-8s (AF) and tergitol 15-s-40 (TG) on CNTs was investigated with dissipative particle dynamics (DPD) simulations, as well as the behavior of the binary surfactant system with CNTs. Properties of surfactants (i.e., critical micelle concentration, aggregation number, shape and size of micelle, and diffusivity) in water were determined to validate the simulation model. Results indicated that the assembly of surfactants (AF and TG) on CNTs depends on the interaction of the surfactant tail and the CNT surface, where surfactants formed mainly hemimicellar structures. For surfactants in solution, most micelles had spherical shape. The particles formed by the CNT and the adsorbed surfactant became hydrophilic, due to the outward orientation of the head groups of the surfactants that formed monolayer adsorption. In the binary surfactant system, the presence of TG on the CNT surface provided a considerable hydrophilic steric effect, due to the EO groups of TG molecules. It was also seen that the adsorption of AF was more favorable than TG on the CNT surface. Diffusion coefficients for the surfactants in the bulk and surface diffusion on the CNT were calculated. These results are applicable, in a qualitative sense, to the more general case of adsorption of surfactants on the hydrophobic surface of cylindrically shaped nanoscale objects.

  19. Polydiacetylene sensor interaction with food sanitizers and surfactants.

    Science.gov (United States)

    Zhang, Yueyuan; Northcutt, Julie; Hanks, Tim; Miller, Ian; Pennington, Bill; Jelinek, Raz; Han, Inyee; Dawson, Paul

    2017-04-15

    Polydiacetylene (PDA) vesicles are of interest as biosensors, particularly for pathogenic bacteria. As part of a food monitoring system, interaction with food sanitizers/surfactants was investigated. PDA vesicles were prepared by inkjet-printing, photopolymerized and characterized by dynamic light scattering (DLS) and UV/Vis spectroscopy. The optical response of PDA vesicles at various concentrations verses a fixed sanitizer/surfactant concentration was determined using a two variable factorial design. Sanitizer/surfactant response at various concentrations over time was also measured. Results indicated that only Vigilquat and TritonX-100 interacted with PDA vesicles giving visible colour change out of 8 sanitizers/surfactants tested. PDA vesicle concentration, sanitizer/surfactant concentration, and time all had a significant (P<0.0001) effect on colour change. As they are highly sensitive to the presence of Vigilquat and TritonX-100, PDA sensors could be used to detect chemical residues as well as for detection of various contaminants in the food industry.

  20. Experimental study on thermophoresis of colloids in aqueous surfactant solutions

    Science.gov (United States)

    Dong, Ruo-Yu; Zhou, Yi; Yang, Chun; Cao, Bing-Yang

    2015-12-01

    Thermophoresis refers to the motion of particles under a temperature gradient and it is one of the particle manipulation techniques. Regarding the thermophoresis of particles in liquid media, however, many open questions still remain, especially the role of the interfacial effect. This work reports on a systematic experimental investigation of surfactant effects, especially the induced interfacial effect, on the thermophoresis of colloids in aqueous solutions via a microfluidic approach. Two kinds of commonly used surfactants, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB), are selected and the results show that from relatively large concentrations, the two surfactants can greatly enhance the thermophilic mobilities. Specifically, it is found that the colloid-water interfaces modified with more polar end groups can potentially lead to a stronger thermophilic tendency. Due to the complex effects of surfactants, further theoretical model development is needed to quantitatively describe the dependence of thermophoresis on the interface characteristics.

  1. Thermodynamic investigations of nitroxoline sublimation by simultaneous DSC-FTIR method and isothermal TG analysis.

    Science.gov (United States)

    Gao, Gau-Yi; Lin, Shan-Yang

    2010-01-01

    To investigate the physicochemical characteristics, thermodynamics, possible sublimation process and kinetics of nitroxoline, differential scanning calorimetry (DSC), isothermal thermogravimetry (TG), and Fourier transform infrared (FTIR) microspectroscopy equipped with a micro hot-stage of DSC microscopy assembly (simultaneous DSC-FTIR method) were used. The DSC result indicates that nitroxoline exhibited a sharp endothermic peak at 182 degrees C with enthalpy of 103.1 J/g due to the melting point of nitroxoline. A sublimation behavior of nitroxoline was found from 129 degrees C by gradual weight loss in TG curve. However, the nonisothermal DSC-FTIR method reveals that the temperature at 95 degrees C was the onset temperature of nitroxoline sublimation. A significant difference between DSC-FTIR method and TG analysis suggests that the simultaneous DSC-FTIR method was more sensitive than that of the TG analysis to detect the beginning temperature of nitroxoline sublimation. The sublimation kinetics of nitroxoline determined by isothermal TG analysis evidenced that the zero-order kinetics was followed over the sublimation time. The sublimation enthalpy correction was also carried out by a group additivity approach for the estimation of heat capacity. The enthalpy of nitroxoline sublimation estimated was 86.14 KJ/mol at 298.15 K.

  2. Degradation of polycyclic aromatic hydrocarbons in the presence of synthetic surfactants.

    OpenAIRE

    Tiehm, A

    1994-01-01

    The biodegradation of polycyclic aromatic hydrocarbons (PAH) often is limited by low water solubility and dissolution rate. Nonionic surfactants and sodium dodecyl sulfate increased the concentration of PAH in the water phase because of solubilization. The degradation of PAH was inhibited by sodium dodecyl sulfate because this surfactant was preferred as a growth substrate. Growth of mixed cultures with phenanthrene and fluoranthene solubilized by a nonionic surfactant prior to inoculation wa...

  3. Effect of Dynamic Surface Tension on Droplet Formation of Surfactant Solution Injected from a Capillary Tube

    OpenAIRE

    山本, 剛宏; 加藤, 有樹; 山下, 敦史; Takehiro, YAMAMOTO; Yuki, Kato; Atsushi, Yamashita; 阪大院工; Osaka University

    2008-01-01

    Effects of dynamic surface tension on the droplet formation of surfactant solutions were studied. Aqueous solutions of CTAB at several surfactant concentrations were used as test fluids. A droplet formed when a surfactant solution was injected from a capillary tube was investigated and the relation between the droplet diameter and the injection velocity was measured. The diameter increased with increasing the velocity at relatively low velocities because the dynamic tension also increased. Ho...

  4. Capillary electrophoresis investigation on equilibrium between polymer-related and surfactant-related species in aqueous polymer-surfactant solutions.

    Science.gov (United States)

    Wu, Yefan; Chen, Miaomiao; Fang, Yun; Zhu, Meng

    2017-03-17

    It was inferred from aqueous solution behavior of nonionic polymers and anionic surfactants that the formation of charged polymer-bound surfactant micelle above critical aggregation concentration (cac) and the formation of free surfactant micelle beyond polymer saturation point (psp), but there was still a lack of direct experimental evidence for the considered equilibrium chemical species. Three modes of capillary electrophoresis are applied in this paper to study the complexation between nonionic polymers, polyvinylpyrrolidone (PVP) or polyethylene glycol (PEG), and sodium dodecylbenzenesulfonate (SDBS) by successfully distinguishing the imaginary charged polymer-bound SDBS micelle from nonionic polymer and SDBS molecule. Perhaps even more important, it is the action of SDBS as both a main surfactant and a UV probe that makes the free surfactant micelle emerged in electropherogram beyond psp, and thus makes it possible for the first time to provide the equilibrium relationship of the polymer-related and the surfactant-related species in the concentration regions divided into by cac and psp. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Selective Antimicrobial Activities and Action Mechanism of Micelles Self-Assembled by Cationic Oligomeric Surfactants.

    Science.gov (United States)

    Zhou, Chengcheng; Wang, Fengyan; Chen, Hui; Li, Meng; Qiao, Fulin; Liu, Zhang; Hou, Yanbo; Wu, Chunxian; Fan, Yaxun; Liu, Libing; Wang, Shu; Wang, Yilin

    2016-02-17

    This work reports that cationic micelles formed by cationic trimeric, tetrameric, and hexameric surfactants bearing amide moieties in spacers can efficiently kill Gram-negative E. coli with a very low minimum inhibitory concentration (1.70-0.93 μM), and do not cause obvious toxicity to mammalian cells at the concentrations used. With the increase of the oligomerization degree, the antibacterial activity of the oligomeric surfactants increases, i.e., hexameric surfactant > tetrameric surfactant > trimeric surfactant. Isothermal titration microcalorimetry, scanning electron microscopy, and zeta potential results reveal that the cationic micelles interact with the cell membrane of E. coli through two processes. First, the integrity of outer membrane of E. coli is disrupted by the electrostatic interaction of the cationic ammonium groups of the surfactants with anionic groups of E. coli, resulting in loss of the barrier function of the outer membrane. The inner membrane then is disintegrated by the hydrophobic interaction of the surfactant hydrocarbon chains with the hydrophobic domains of the inner membrane, leading to the cytoplast leakage. The formation of micelles of these cationic oligomeric surfactants at very low concentration enables more efficient interaction with bacterial cell membrane, which endows the oligomeric surfactants with high antibacterial activity.

  6. Computational modeling of unsteady surfactant-laden liquid plug propagation in neonatal airways

    Science.gov (United States)

    Olgac, Ufuk; Muradoglu, Metin

    2013-07-01

    Surfactant-free and surfactant-laden liquid plug propagation in neonatal airways in various generations representing the upper and lower airways are investigated computationally using a finite-difference/front-tracking method. Emphasis is placed on the unsteady surfactant-laden plug propagation as a model for Surfactant Replacement Therapy (SRT) and airway reopening. The numerical method is designed to solve the evolution equations of the interfacial and bulk surfactant concentrations coupled with the incompressible Navier-Stokes equations. Available experimental data for surfactant Survanta are used to relate surface tension coefficient to surfactant concentration at the interface. It is found that, for the surfactant-free case, the trailing film thickness is in good agreement with Taylor's law for plugs with plug length greater than the airway width. Mechanical stresses that could be injurious to epithelial cells such as pressure and shear stress and their gradients are maximized on the front and rear menisci with increasing magnitudes in the lower generations. These mechanical stresses, especially pressure and pressure gradient, are diminished with the introduction of surfactants. Surfactant is absorbed onto the trailing film and thickens it, eventually leading to either plug rupture or, if totally consumed prior to rupture, to steadily propagating plug. In the upper airways, initially small plugs rupture rapidly and plugs with comparable initial plug length with the airway width persist and propagate steadily. For a more effective SRT treatment, we recommend utilization of plugs with initial plug length greater than the airway width. Increasing surfactant strength or increasing the initially instilled surfactant concentration is found to be ineffective.

  7. Influência de alguns parâmetros experimentais nos resultados de análises calorimétricas diferenciais - DSC Influence of some experimental parameters on the results of differential scanning calorimetry - DSC.

    Directory of Open Access Journals (Sweden)

    Cláudia Bernal

    2002-09-01

    Full Text Available A series of experiments were performed in order to demonstrate to undergraduate students or users of the differential scanning calorimetry (DSC, that several factors can influence the qualitative and quantitative aspects of DSC results. Saccharin, an artificial sweetner, was used as a probe and its thermal behavior is also discussed on the basis of thermogravimetric (TG and DSC curves.

  8. 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...

  9. Surfactant adsorption kinetics in microfluidics

    Science.gov (United States)

    Riechers, Birte; Maes, Florine; Akoury, Elias; Semin, Benoît; Gruner, Philipp; Baret, Jean-Christophe

    2016-10-01

    Emulsions are metastable dispersions. Their lifetimes are directly related to the dynamics of surfactants. We design a microfluidic method to measure the kinetics of adsorption of surfactants to the droplet interface, a key process involved in foaming, emulsification, and droplet coarsening. The method is based on the pH decay in the droplet as a direct measurement of the adsorption of a carboxylic acid surfactant to the interface. From the kinetic measurement of the bulk equilibration of the pH, we fully determine the adsorption process of the surfactant. The small droplet size and the convection during the droplet flow ensure that the transport of surfactant through the bulk is not limiting the kinetics of adsorption. To validate our measurements, we show that the adsorption process determines the timescale required to stabilize droplets against coalescence, and we show that the interface should be covered at more than 90% to prevent coalescence. We therefore quantitatively link the process of adsorption/desorption, the stabilization of emulsions, and the kinetics of solute partitioning—here through ion exchange—unraveling the timescales governing these processes. Our method can be further generalized to other surfactants, including nonionic surfactants, by making use of fluorophore-surfactant interactions.

  10. Monsoon influences distribution of surfactants at different coastal areas into atmospheric aerosol

    Science.gov (United States)

    Shaharom, Suhana; Latif, Mohd Talib; Khan, Md Firoz

    2016-11-01

    Global climate change can be influenced by surfactants because of its characteristics due to reduce surface tension. The aim of this study was to determine the composition of surfactants in atmospheric aerosol. Fine aerosol sample diameter size (<1.5 µM) were collected using High Volume Air Sampler (HVAS) for 24 hrs with flow rate of 1.13m3min-1 at different coastal areas. Colorimetric method was undertaken to determine the concentrations of anionic surfactants as methylene blue active substances (MBAS) and cationic surfactants as dimethyl blue active substances (DBAS) using a UV spectrometer. The results indicated that the concentration of anionic surfactants was higher than concentration of cationic surfactants. Therefore, the concentrations of surfactants in Port Dickson was 103.97 pmolm-3 for MBAS and 62.57 pmolm-3 for DBAS and was higher than Bachok during southwest monsoon and meanwhile concentrations of surfactants was higher in Bachok 102.74 pmolm-3 for MBAS and DBAS 68.56 pmolm-3 during northeast monsoon.

  11. Anaerobic digestion of aircraft deicing fluid wastes: interactions and toxicity of corrosion inhibitors and surfactants.

    Science.gov (United States)

    Gruden, Cyndee L; Hernandez, Mark

    2002-01-01

    Corrosion inhibitors and surfactants are present in aircraft deicing fluids (ADFs) at significant concentrations (> 1% w/w). The purpose of this research was to study the interactions of a common nonionic surfactant with the commercially significant corrosion inhibitors used in modern ADF (4- and 5-methylbenzotriazole [MeBT]), and to determine the effects of their mixture on the conventional anaerobic digestion process. In mesophilic anaerobic microcosms codigesting wastewater solids, propylene glycol, and MeBT, increasing surfactant levels resulted in enhanced MeBT sorption on digester solids. As judged by anaerobic toxicity assays, responses from digesters containing surfactant concentrations below their critical micelle concentration (CMC) suggested that low nonionic surfactant concentrations could facilitate a reduction in the apparent toxicity of MeBT. In microcosms exposed to surfactant concentrations above their CMC, no increase in MeBT solubility was observed, and the anaerobic toxicity response corresponded to control systems not containing surfactant. Direct microscopic measurements of digesting biomass using fluorescent phylogenetic probes (fluorescent in situ hybridization) revealed that members of the domain Bacteria were more sensitive to MeBT in the presence of surfactant than were members of the domain Archaea.

  12. The Krafft temperature of surfactant solutions

    Directory of Open Access Journals (Sweden)

    Manojlović Jelena Ž.

    2012-01-01

    Full Text Available Our main motivation to revisit the solution properties of cetyltrimethylammonium bromide is related to the clear requirement for better control of the adsorption parameters to form uniform self-assembled monolayers on muscovite mica substrates. To readily monitor the temporal evolution of structural details in cetyltrimethylammonium bromide solutions, we realized a rather simple conductivity experiment. Conductivity measurements were carried out as a function of temperature, to look closer into the Krafft temperature behavior of this surfactant. We measured the electrical conductivity of different concentrations of aqueous cetyltrimethylammonium bromide solutions, below and above the critical micells concentration.

  13. Growth Mechanism of Gold Nanorods in Binary Surfactant System

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-06-15

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

  14. Surfactants enhance recovery of poorly soluble drugs during microdialysis sampling

    DEFF Research Database (Denmark)

    Koplin, Sebastian; Kumpugdee-Vollrath, Mont; Bauer-Brandl, Annette

    2017-01-01

    Aim of this project was to investigate the applicability of a recently developed in vitro microdialysis-sampling approach in connection with a dissolution-/permeation (D/P) system, especially the impact of surfactants within the perfusion fluid. The D/P-system is based on side-by-side chambers...... drug-dissolution (-release) and drug permeation. Furthermore, it should allow quantification of the unbound (free) drug concentration. In the first step, it was assessed, if the addition of the anionic surfactant sodium dodecyl sulphate (SDS) to the perfusate of the microdialysis system affects...... celecoxib, i.e. the fraction of drug, which is not associated with taurocholate surfactant micelles. In buffer, the measured concentrations matched the overall CXB concentrations. By the use of SDS-containing perfusates microdialysis sampling enabled reliable quantification of minute amounts of free CXB...

  15. Electrophoretic separations in poly(dimethylsiloxane) microchips using mixtures of ionic, nonionic and zwitterionic surfactants.

    Science.gov (United States)

    Guan, Qian; Noblitt, Scott D; Henry, Charles S

    2012-09-01

    The use of surfactant mixtures to affect both EOF and separation selectivity in electrophoresis with PDMS substrates is reported, and capacitively coupled contactless conductivity detection is introduced for EOF measurement on PDMS microchips. First, the EOF was measured for two nonionic surfactants (Tween 20 and Triton X-100), mixed ionic/nonionic surfactant systems (SDS/Tween 20 and SDS/Triton X-100), and finally for the first time, mixed zwitterionic/nonionic surfactant systems (TDAPS/Tween 20 and TDAPS/Triton X-100). EOF for the nonionic surfactants decreased with increasing surfactant concentration. The addition of SDS or TDAPS to a nonionic surfactant increased EOF. After establishing the EOF behavior, the separation of model catecholamines was explored to show the impact on separations. Similar analyte resolution with greater peak heights was achieved with mixed surfactant systems containing Tween 20 and TDAPS relative to the single surfactant system. Finally, the detection of catecholamine release from PC12 cells by stimulation with 80 mM K(+) was performed to demonstrate the usefulness of mixed surfactant systems to provide resolution of biological compounds in complex samples.

  16. Determination of melting point of vegetable oils and fats by differential scanning calorimetry (DSC technique.

    Directory of Open Access Journals (Sweden)

    Nassu, Renata Tieko

    1999-02-01

    Full Text Available Melting point of fats is used to characterize oils and fats and is related to their physical properties, such as hardness and thermal behaviour. The present work shows the utilization of DSC technique on the determination of melting point of fats. In a comparison with softening point (AOCS method Cc 3-25, DSC values were higher than those obtained by AOCS method. It has occurred due to the fact that values obtained by DSC technique were taken when the fat had melted completely. DSC was also useful for determining melting point of liquid oils, such as soybean and cottonseed ones.

    El punto de fusión de grasas es usado para caracterizar aceites y grasas, y está relacionado con sus propiedades físicas, tales como dureza y comportamiento térmico. El presente trabajo muestra la utilización de la técnica de Calorimetría Diferencial de Barrido (DSC en la determinación del punto de fusión de grasas. En comparación con el punto de ablandamiento (AOCS método Cc 3-25, los valores de DSC fueron más altos que los obtenidos por los métodos de AOCS. Esto ha ocurrido debido al hecho que los valores obtenidos por la técnica de DSC fueron tomados cuando la grasa había fundido completamente. DSC fue también útil para determinar puntos de fusión de aceites líquidos, tales como los de soya y algodón.

  17. Perfusion deconvolution in DSC-MRI with dispersion-compliant bases.

    Science.gov (United States)

    Pizzolato, Marco; Boutelier, Timothé; Deriche, Rachid

    2017-02-01

    Perfusion imaging of the brain via Dynamic Susceptibility Contrast MRI (DSC-MRI) allows tissue perfusion characterization by recovering the tissue impulse response function and scalar parameters such as the cerebral blood flow (CBF), blood volume (CBV), and mean transit time (MTT). However, the presence of bolus dispersion causes the data to reflect macrovascular properties, in addition to tissue perfusion. In this case, when performing deconvolution of the measured arterial and tissue concentration time-curves it is only possible to recover the effective, i.e. dispersed, response function and parameters. We introduce Dispersion-Compliant Bases (DCB) to represent the response function in the presence and absence of dispersion. We perform in silico and in vivo experiments, and show that DCB deconvolution outperforms oSVD and the state-of-the-art CPI+VTF techniques in the estimation of effective perfusion parameters, regardless of the presence and amount of dispersion. We also show that DCB deconvolution can be used as a pre-processing step to improve the estimation of dispersion-free parameters computed with CPI+VTF, which employs a model of the vascular transport function to characterize dispersion. Indeed, in silico results show a reduction of relative errors up to 50% for dispersion-free CBF and MTT. Moreover, the DCB method recovers effective response functions that comply with healthy and pathological scenarios, and offers the advantage of making no assumptions about the presence, amount, and nature of dispersion. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. The terminal solid solubility of hydrogen in Zircaloy-4 and Opt-ZIRLO with a DSC

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae-hoon; Kim, Yong-soo [Hanyang Univ., Seoul (Korea, Republic of); Kim, Ju-seong [Korea Atomic Energy Institute, Daejeon (Korea, Republic of)

    2014-10-15

    Due to low neutron absorption cross section, good mechanical properties at high temperature and proper corrosion resistance; zirconium-based materials have been used commonly for nuclear core structural components. When the hydrogen content in cladding exceeds the terminal solid solubility (TSS) of hydrogen, the brittle hydrides can be precipitated. The brittle hydrides can threaten the integrity of cladding such as hydride re-orientation or DHC in dry storage conditions as well as in reactor operating conditions. In addition, it is known that the terminal solid solubility of hydrogen in zirconium alloys for dissolution (TSSD) and precipitation (TSSP) has a significant hysteresis. Thus, the TSS of hydrogen in zirconium alloys is an important factor and accurate knowledge of the TSS is required for evaluation of cladding integrity. In this study, the TSSD and TSSP for Zircaloy-4 and Opt-ZIRLO were measured. The TSS of hydrogen in Zry-4 and Opt-ZIRLO was investigated with a DSC in this study. The hydrogen concentrations in zirconium alloys ranged 40-741 wppm. Both TSSD and TSSP were similar to literature TSS results. However, Opt-ZIRLO had a higher terminal solid solubility of hydrogen than Zry-4 at the same temperature for less than about 400 wppm. The activation energy of Zircaloy-4 was relatively high compared with references, while the activation energy of Opt-ZIRLO was relatively low. It was considered that the chemical composition affects the TSS.

  19. Interaction between cationic surfactant of 1-methyl-3-tetradecylimidazolium bromide and anionic polymer of sodium polystyrene sulfonate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qian [College of Chemistry and Chemical Engineering, Liaocheng University, Shandong Province, VIC 252059 (China); School of Chemistry and Chemical Engineering, Engineering Research Center for Fine Chemicals of Ministry of Education, Shanxi University, Shanxi Province, VIC 030006 (China); Kang, Wenpei [Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Shandong Province, VIC 250100 (China); Sun, Dezhi [College of Chemistry and Chemical Engineering, Liaocheng University, Shandong Province, VIC 252059 (China); Liu, Jie, E-mail: liujie@lcu.edu.cn [College of Chemistry and Chemical Engineering, Liaocheng University, Shandong Province, VIC 252059 (China); Wei, Xilian, E-mail: weixilian@126.com [College of Chemistry and Chemical Engineering, Liaocheng University, Shandong Province, VIC 252059 (China)

    2013-08-15

    The interaction between long-chain imidazolium ionic liquid (C{sub 14}mimBr) and anionic polyelectrolyte of sodium polystyrene sulfonate (NaPSS) has been studied using surface tension, isothermal titration microcalorimetry (ITC), dynamic light scatting (DLS) and conductance methods. The result shows that the surface tension plots have a pronounced hump in the surface tension at surfactant concentrations below the critical micelle concentration (cmc) of the surfactant. The cooperative adsorption of surfactant and polymer on the surface (PS{sub S}) and the formation of polymer/surfactant aggregate in bulk solution (PS{sub M}) provide a rational explanation about it. The formation of surfactant/polymer complexes is affected by the concentration of the surfactant or NaPSS, which is also ascertained by ITC and DLS measurements. Further, the thermodynamic parameters are derived from calorimetric titration and conductance curves, and the effects of polymer concentration and temperature on the parameters are evaluated in detail.

  20. Identification of the thermal transitions in potato starch at a low water content as studied by preparative DSC

    NARCIS (Netherlands)

    Steeneken, P.A.M.; Woortman, A.J.J.

    2009-01-01

    The aim of this work was to identify the transitions in the complex DSC profiles of potato starch at a low water content. Preparative DSC involves the thermal processing of samples in stainless steel DSC pans in a way that allows their subsequent structural characterization. The low temperature (LT)

  1. Identification of the thermal transitions in potato starch at a low water content as studied by preparative DSC

    NARCIS (Netherlands)

    Steeneken, P.A.M.; Woortman, A.J.J.

    2009-01-01

    The aim of this work was to identify the transitions in the complex DSC profiles of potato starch at a low water content. Preparative DSC involves the thermal processing of samples in stainless steel DSC pans in a way that allows their subsequent structural characterization. The low temperature

  2. Effect of curcumin on the binding of cationic, anionic and nonionic surfactants with myoglobin

    Science.gov (United States)

    Mondal, Satyajit; Ghosh, Soumen

    2017-04-01

    Interaction of a globular protein, myoglobin and different surfactants has been studied in the absence and presence of curcumin in phosphate buffer at pH = 7.4 by UV-VIS spectrophotometry, fluorimetry and fluorescence polarization anisotropy methods. Results show that heme environment of myoglobin is changed by cationic cetyltrimethylammonium bromide (CTAB) and sodium N-dodecanoyl sarcosinate (SDDS). In the presence of curcumin, CTAB cannot change the heme; but SDDS can make change. Nonionic surfactant N-decanoyl-N-methylglucamine (Mega 10) cannot change the heme environment. Protein is unfolded by the surfactant. Curcumin can prevent the unfolding of protein in the low concentration region of ionic surfactants such as CTAB and SDDS. In nonionic surfactant media, curcumin accelerates the denaturation process. Due to myoglobin-curcumin complex formation, rotational motion of curcumin decreases in surfactant media and so anisotropy increases.

  3. Evaluation of surfactants as solubilizing agents in microsomal metabolism reactions with lipophilic substrates.

    Science.gov (United States)

    Randall, Kathleen; Cheng, Shun Wen; Kotchevar, Anne Therese

    2011-10-01

    Solubilizing agents are routinely added when investigating the biotransformation of lipophilic substrates using hepatic microsomes. For highly lipophilic compounds, the concentration of solvent or surfactant necessary for dissolution can be detrimental to enzyme activity. This study evaluates the effect of 12 surfactants on microsomal metabolism and the ability of the same surfactants to improve the aqueous solubility of the pentabrominated diphenyl ether BDE-100, a lipophilic environmental contaminant previously found to be recalcitrant to in vitro metabolism. Of the surfactants investigated, Cremophor EL and Tween 80 displayed the best combination of increased BDE-100 solubility and minimal inhibition of microsomal metabolism. However, a comparison of the in vitro metabolism products of BDE-100 in the presence of the two surfactants revealed varying amounts of metabolites depending on the surfactant used.

  4. Solution behaviour of new cationic surfactants derived from Guerbet alcohols and their use in hair conditioners.

    Science.gov (United States)

    Yahagi, K; Hoshino, N; Hirota, H

    1991-10-01

    Summary The solution behaviour of new cationic surfactants, synthesized by using long-chain Guerbet alcohols, in water was investigated by a polarizing microscopic technique, differential scanning calorimetry, and electric conductivity measurements. These surfactants show the gel-liquid crystalline phase transition to be lower than 0 degrees C and form lamellar liquid crystals even in cold water and at low concentrations of surfactants. The sorption of cationic surfactants from aqueous solutions onto hair was determined as a function of temperature. The effect of adsorbed cationic surfactants on the critical surface tension and kinetic frictional coefficients of hair surface have been investigated. These surface characteristics of hair treated with quaternary ammonium compounds derived from Guerbet alcohols were found to be significantly improved. These results can be explained by the high ability of sorption onto hair. Hair rinses and conditioners having excellent ease of combing or brushing for wet and dry hair can be formulated by the application of these cationic surfactants.

  5. Effect of the surfactant on the availability of piroxicam as a poorly hydrosoluble drug from suppositories.

    Science.gov (United States)

    Dal Zorro, M; Franceschinis, E; Punchina, A; Realdon, N

    2012-01-01

    The use of surfactants in suppository formulations has been suggested to improve availability of poorly soluble drugs. In the present study, different kinds of surfactants have been investigated to clarify the influence on piroxicam release from suppositories formulated with both lipophilic and hydrophilic bases. Two hydrophilic glucose-derivate surfactants, and a polyoxylglyceride amphiphilic surfactant, all with high HLB values, were investigated for their use in improving drug availability. The two glucose derivate surfactants reduced drug availability from both lipophilic suppositories and hydrophilic formulations, according to longer disintegration times and drug micellization. The more complex surfactant, a lauroyl macrogolglyceride, showed an increase in piroxicam availability from lipophilic suppositories at the higher tested concentrations (15% and 20%). Otherwise, when used in hydrophilic formulations, it was less effective in promoting drug release and even reduced drug availability.

  6. EFFECT OF SURFACTANTS ON Ni-TiN NANOCOMPOSITE COATINGS PREPARED BY ULTRASONIC ELECTRODEPOSITION

    Institute of Scientific and Technical Information of China (English)

    XIA Fafeng; JIA Zhenyuan; WU Menghua; LI Zhi

    2008-01-01

    Ni-TiN nanocomposite coatings were prepared by ultrasonic electrodeposition, and the effects of the surfactants on the coatings were investigated and the microstructure and micro rigidity of the coatings were characterized. Samples were also submitted to corrosion tests in 3% NaCl solution. The results showed that the surfactants had great effects on Ni-TiN nanocomposite coatings. The composite coatings prepared by ultrasonic electrodeposition with the surfactants were better than that of the coatings prepared without surfactants. The favorable properties of Ni-TiN nanocomposite coatings were prepared with the mixing of the non-ion and positive ion surfactants. The concentration of the mixing was 80 mg/L, and the ratio of the non-ion and positive ion surfactants was 1: 2.

  7. Innovation in surfactant therapy II: surfactant administration by aerosolization.

    Science.gov (United States)

    Pillow, J Jane; Minocchieri, S

    2012-01-01

    Instilled bolus surfactant is the only approved surfactant treatment for neonatal respiratory distress syndrome. However, recent trends towards increased utilization of noninvasive respiratory support for preterm infants with surfactant deficiency have created a demand for a similarly noninvasive means of administering exogenous surfactant. Past approaches to surfactant nebulization met with varying success due to inefficient aerosol devices resulting in low intrapulmonary delivery doses of surfactant with variable clinical effectiveness. The recent development of vibrating membrane nebulizers, coupled with appropriate positioning of the interface device, indicates that efficient delivery of aerosolized surfactant is now a realistic goal in infants. Evidence of clinical effect despite low total administered dose in pilot studies, together with suggestions of enhanced homogeneity of pulmonary distribution indicate that this therapy may be applied in a cost-effective manner, with minimal patient handling and disruption. These studies need to be subjected to appropriately designed randomized controlled trials. Further work is also required to determine the optimum delivery route (mask, intranasal prong, nasopharyngeal or laryngeal), dosing amount and redosing interval.

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

    Science.gov (United States)

    Aloui, Fathi; Kchaou, Sonia; Sayadi, Sami

    2009-05-15

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

  9. Solubilization isotherms of aromatic solutes in surfactant aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Gadelle, F.; Koros, W.J.; Schechter, R.S. (Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering)

    1995-03-01

    Several factors affecting solubilization of aromatic solutes in surfactant micelles have been investigated. Solubilization isotherms of benzene, toluene, and chlorobenzene in various aqueous micellar solutions were determined using head space gas chromatography. Cationic surfactants such as cetylpyridinium chloride or cetyltrimethylammonium bromide present high solubilization capacities. Comparable anionic surfactants exhibit lower solubilization and a greater tendency to precipitate. It was observed that nonionic surfactants show high solubilization on a molar basis. Solubilization in mixed cationic-anionic micelles was also investigated. It also appears that the molecular size of the solute determines the extent of the solubilization. Finally, the shape of the different isotherms indicates that knowing the amount solubilized at saturation of the micellar solution is not sufficient to estimate solubilization at solute concentrations lower than the solute aqueous solubility. Solubilization of organics in surfactant micelles is of major importance in many applications. One new application is micellar-enhanced ultrafiltration. Another application of interest is the surfactant-enhanced aquifer remediation, a process in which a micellar aqueous solution is flushed into contaminated groundwaters to enhance recovery of pollutants by micellar solubilization.

  10. Recent advances and potential applications of modulated differential scanning calorimetry (mDSC) in drug development.

    Science.gov (United States)

    Knopp, Matthias Manne; Löbmann, Korbinian; Elder, David P; Rades, Thomas; Holm, René

    2016-05-25

    Differential scanning calorimetry (DSC) is frequently the thermal analysis technique of choice within preformulation and formulation sciences because of its ability to provide detailed information about both the physical and energetic properties of a substance and/or formulation. However, conventional DSC has shortcomings with respect to weak transitions and overlapping events, which could be solved by the use of the more sophisticated modulated DSC (mDSC). mDSC has multiple potential applications within the pharmaceutical field and the present review provides an up-to-date overview of these applications. It is aimed to serve as a broad introduction to newcomers, and also as a valuable reference for those already practising in the field. Complex mDSC was introduced more than two decades ago and has been an important tool for the quantification of amorphous materials and development of freeze-dried formulations. However, as discussed in the present review, a number of other potential applications could also be relevant for the pharmaceutical scientist.

  11. Applications of differential scanning calorimetry for thermal stability analysis of proteins: qualification of DSC.

    Science.gov (United States)

    Wen, Jie; Arthur, Kelly; Chemmalil, Letha; Muzammil, Salman; Gabrielson, John; Jiang, Yijia

    2012-03-01

    Differential scanning calorimetry (DSC) has been used to characterize protein thermal stability, overall conformation, and domain folding integrity by the biopharmaceutical industry. Recently, there have been increased requests from regulatory agencies for the qualification of characterization methods including DSC. Understanding the method precision can help determine what differences between samples are significant and also establish the acceptance criteria for comparability and other characterization studies. In this study, we identify the parameters for the qualification of DSC for thermal stability analysis of proteins. We use these parameters to assess the precision and sensitivity of DSC and demonstrate that DSC is suitable for protein thermal stability analysis for these purposes. Several molecules from different structural families were studied. The experiments and data analyses were performed by different analysts using different instruments at different sites. The results show that the (apparent) thermal transition midpoint (T(m)) values obtained for the same protein by same and different instruments and/or analysts are quite reproducible, and the profile similarity values obtained for the same protein from the same instrument are also high. DSC is an appropriate method for assessing protein thermal stability and conformational changes.

  12. Changes of multi-scale structure during mimicked DSC heating reveal the nature of starch gelatinization.

    Science.gov (United States)

    Wang, Shujun; Zhang, Xiu; Wang, Shuo; Copeland, Les

    2016-06-20

    A thorough understanding of starch gelatinization is extremely important for precise control of starch functional properties for food processing and human nutrition. Here we reveal the molecular mechanism of starch gelatinization by differential scanning calorimetry (DSC) in conjunction with a protocol using the rapid viscosity analyzer (RVA) to generate material for analysis under conditions that simulated the DSC heating profiles. The results from DSC, FTIR, Raman, X-ray diffraction and small angle X-ray scattering (SAXS) analyses all showed that residual structural order remained in starch that was heated to the DSC endotherm end temperature in starch:water mixtures of 0.5 to 4:1 (v/w). We conclude from this study that the DSC endotherm of starch at a water:starch ratio of 2 to 4 (v/w) does not represent complete starch gelatinization. The DSC endotherm of starch involves not only the water uptake and swelling of amorphous regions, but also the melting of starch crystallites.

  13. Changes of multi-scale structure during mimicked DSC heating reveal the nature of starch gelatinization

    Science.gov (United States)

    Wang, Shujun; Zhang, Xiu; Wang, Shuo; Copeland, Les

    2016-06-01

    A thorough understanding of starch gelatinization is extremely important for precise control of starch functional properties for food processing and human nutrition. Here we reveal the molecular mechanism of starch gelatinization by differential scanning calorimetry (DSC) in conjunction with a protocol using the rapid viscosity analyzer (RVA) to generate material for analysis under conditions that simulated the DSC heating profiles. The results from DSC, FTIR, Raman, X-ray diffraction and small angle X-ray scattering (SAXS) analyses all showed that residual structural order remained in starch that was heated to the DSC endotherm end temperature in starch:water mixtures of 0.5 to 4:1 (v/w). We conclude from this study that the DSC endotherm of starch at a water:starch ratio of 2 to 4 (v/w) does not represent complete starch gelatinization. The DSC endotherm of starch involves not only the water uptake and swelling of amorphous regions, but also the melting of starch crystallites.

  14. 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.

  15. How Chain Length and Charge Affect Surfactant Denaturation of Acyl Coenzyme A Binding Protein (ACBP)

    DEFF Research Database (Denmark)

    Andersen, Kell Kleiner; Otzen, Daniel

    2009-01-01

    Using intrinsic tryptophan fluorescence, equilibria and kinetics of unfolding of acyl coenzyme A binding protein (ACBP) have been investigated in sodium alkyl sulfate surfactants of different chain length (8-16 carbon atoms) and with different proportions of the nonionic surfactant dodecyl...... maltoside (DDM). The aim has been to determine how surfactant chain length and micellar charge affect the denaturation mechanism. ACBP denatures in two steps irrespective of surfactant chain length, but with increasing chain length, the potency of the denaturant rises more rapidly than the critical micelle...... constants increases linearly with denaturant concentration below the cmc but declines at higher concentrations. Both shortening chain length and decreasing micellar charge reduce the overall kinetics of unfolding and makes the dependence of unfolding rate constants on surfactant concentration more complex...

  16. Molecular dynamics simulations of phase separation in the presence of surfactants

    DEFF Research Database (Denmark)

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

    1994-01-01

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

  17. Partition and water/oil adsorption of some surfactants.

    Science.gov (United States)

    Tadmouri, Rawad; Zedde, Chantal; Routaboul, Corinne; Micheau, Jean-Claude; Pimienta, Véronique

    2008-10-02

    Adsorption isotherms have been determined at the water/oil interface for five biphasic systems involving surfactants (non-ionic and ionic) present in both phases at partition equilibrium. The systems studied were polyoxyethylene(23)lauryl ether (Brij35) in water/hexane and four ionic surfactants, hexadecyltrimethylammonium bromide (CTAB), and a series of three tetraalkylammonium dodecylsulfate (TEADS, TPADS, and TBADS) in water/CH 2Cl 2. Interfacial tension measurements performed at the water/air and water/oil interfaces provided all the necessary information for the determination of the adsorption parameters by taking partition into account. These measurements also allowed the comparison of the adsorption properties at both interfaces which showed an increase of the adsorption equilibrium constant and a decrease of the maximum surface concentration at the water/oil interface compared to water/air. The values of the critical aggregation concentration showed, in all cases, that only the surfactant dissolved in the aqueous phase contribute to the decrease of the water/oil interfacial tension. In the case of the four ionic surfactants, the critical aggregation concentration obtained in biphasic conditions were lowered because of the formation of mixed surfactant-CH 2Cl 2 aggregates.

  18. INFLUENCE OF CULTIVATION CONDITIONS ON ANTIMICROBIAL PROPERTIES OF Nocardia vaccinii ІMV B-7405 SURFACTANTS

    Directory of Open Access Journals (Sweden)

    Т. P.

    2016-02-01

    Full Text Available The aim of the work was investigation of antimicrobial effect of Nocardia vaccinii ІMV B-7405 surfactants, synthesized in various culture conditions, against phytopathogenic bacteria of genera Pseudomonas, Xanthomonas, and Pectobacterium. The antimicrobial properties of surfactant were determined in suspension culture by Koch method and also by index of the minimum inhibitory concentration. Surfactants were extracted from supernatant of cultural liquid using mixture of chloroform and methanol (2: 1. It has been established that antimicrobial properties of surfactants depend on the nature of the carbon source in the medium (refined vegetable oil, as well as waste oil after frying potatoes and meat, glycerol, the duration of the cultivation (5 and 7 days, the degree of purification of the surfactants (the supernatant of cultural liquid, purified surfactants solution and the test culture type. The highest antimicrobial activity was exhibited by purified surfactants solutions synthesized by microorganisms on the waste oil after potato frying (decreased survival of pathogenic bacteria by 50–95%, and surfactants formed within 7 days of strain B-7405 ІMV cultivation on all test substrates (minimum inhibitory concentration 7–40 µg/mL, which is several times lower than the surfactant, synthesized for 5 days. These data are promising for the development of ecologically friendly biopreparations for the regulation of the number of phytopathogenic bacteria.

  19. Pyrene removal from contaminated soil using electrokinetic process combined with surfactant

    Directory of Open Access Journals (Sweden)

    Seyed Enayat Hashemi

    2015-07-01

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

  20. A conductometric investigation of hydroxypropylmethyl cellulose/sodium dodecyl sulfate/nonionic surfactant systems

    Directory of Open Access Journals (Sweden)

    Petrović Lidija B.

    2014-01-01

    Full Text Available Surfactant mixtures are very often used in various cosmetic and pharmaceutical products because they commonly act in synergism and provide more favorable properties than the single surfactants. At the same time, the 9 presence of polymers in mixtures of surfactants may lead to molecular interactions thereby affecting product stability and activity. For these reasons it is very important to determine the surfactant interactions influence on 1micellization and mixed micellization, as well as polymer-surfactants mixed micelles interactions. In this work we examined self-aggregation of nonionic surfactants, polysorbate 20 (Tween 20, polyoxyethylene octylphenyl ether (Triton X100 and polyoxyethylene-polyoxypropylene block copolymer (Pluronic F68 with ionic surfactant, sodium dodecylsulfate, in aqueous solution at 40ºC using conductometric titration method. It was found that concentration region for mixed micelle formation depends on nonionic surfactant characteristics and its concentration. Formation of surfactants mixed micelles in the presence of nonionic polymer, hydroxypropylmethyl cellulose, and their binding to polymer hydrophobic sites, were investigated too. Analysis of obtained results points to different kinds of interactions in investigated systems, which are crucial for their application. [Projekat Ministarstva nauke Republike Srbije, br. III 46010

  1. The glass transition process in humid biopolymers. DSC study

    Energy Technology Data Exchange (ETDEWEB)

    Grunina, N A; Belopolskaya, T V; Tsereteli, G I [V.A. Fock Research Institute for Physics of Saint-Petersburg State University, 198504, Petrodvorets (Russian Federation)

    2006-05-15

    Thermal properties of native and denatured biopolymers with quite different chemical and steric structure (globular and fibrillar proteins, DNA, starches) were studied by means of differential scanning calorimetry in a wide range of temperatures and concentrations of water. It was shown that both native and denatured humid biopolymers are glassy systems. The glass transition temperature of these systems strongly depends on percentage of water, with water being simultaneously an intrinsic element of systems' ordered structure and a plasticizer of its amorphous state. On the base of the absolute values of heat capacities for biopolymer-water systems as a whole, heat capacities for biopolymers themselves were calculated as functions on water concentration at fixed temperatures. The S-shaped change of heat capacity observed on diagrams of state both for native and denatured biopolymers is the manifestation of biopolymers' passing through the vitrification region, as it occurs for denatured samples at heating.

  2. Effect of Spacers on CMCs and Micelle-forming Enthalpies of Gemini Surfactants by Titration Microcalorimetry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The critical micelle concentrations (CMC) and the micelle-forming enthalpies (D Hmic) of gemini surfactants were first measured by the precise titration microcalorimetry. The results showed that D Hmic values are negative, and there is an exothermal minimum between s=4 and s=6. Furthermore, the CMCs of the surfactants are in good agreement with literature values.

  3. Thin Film Equations with Soluble Surfactant and Gravity: Modeling and Stability of Steady States

    CERN Document Server

    Escher, Joachim; Laurençot, Philippe; Walker, Christoph

    2010-01-01

    A thin film on a horizontal solid substrate and coated with a soluble surfactant is considered. The governing degenerate parabolic equations for the film height and the surfactant concentrations on the surface and in the bulk are derived using a lubrication approximation when gravity is taken into account. It is shown that the steady states are asymptotically stable.

  4. Classification of calorimetric titration plots for alkyltrimethylammonium and alkylpyridinium cationic surfactants in aqueous solutions

    NARCIS (Netherlands)

    Bijma, K; Engberts, J.B.F.N.; Blandamer, M.J; Cullis, P.M.; Last, P.M.; Irlam, K.D.; Soldi, L.G.

    1997-01-01

    Calorimetric titration plots for deaggregation of micelles formed by alkylpyridinium and alkyltrimethylammonium surfactants are classified into three types, A, B and C, depending on the shape of the plot of the enthalpy of dilution as a function of surfactant concentration. For Type A plots the reco

  5. Classification of calorimetric titration plots for alkyltrimethylammonium and alkylpyridinium cationic surfactants in aqueous solutions

    NARCIS (Netherlands)

    Bijma, K; Engberts, J.B.F.N.; Blandamer, M.J; Cullis, P.M.; Last, P.M.; Irlam, K.D.; Soldi, L.G.

    1997-01-01

    Calorimetric titration plots for deaggregation of micelles formed by alkylpyridinium and alkyltrimethylammonium surfactants are classified into three types, A, B and C, depending on the shape of the plot of the enthalpy of dilution as a function of surfactant concentration. For Type A plots the

  6. Structure of the SDS/1-dodecanol surfactant mixture on a graphite surface: a computer simulation study.

    Science.gov (United States)

    Domínguez, Hector

    2010-05-15

    Molecular dynamics simulations of mixtures of sodium dodecyl sulfate (SDS) and 1-dodecanol molecules on a graphite surface were carried out at low and high concentration to investigate the formation of aggregates on the solid plate. The simulations showed that at low concentration the surfactants were well adsorbed on the surface by forming layers structures or a hemicylinder aggregate for a slightly higher surfactant concentration whereas at the highest concentration the surfactants formed monolayer-like structures localized away from the graphite surface with a water bin between the monolayer and the graphite plate. Therefore, we obtained different arrays of those observed in recent simulations of pure SDS adsorbed on graphite at the same concentration reported in the literature. The unexpected water layer between the 1-dodecanol and the graphite surface, at the highest concentration, was explained in terms of the Hamaker constants. The present results suggest that the formation of aggregates on solid surfaces is a combined effect not only of the surfactant-surfactant and the surfactant-wall interactions but also of the surfactant concentration.

  7. Water repellency induced by pulmonary surfactants.

    Science.gov (United States)

    Hills, B A

    1982-04-01

    1. Pure cotton fabric was partially carboxylated to produce a tough, porous, hydrophilic sub-phase to stimulate the epithelial membrane of the alveolar wall from a permeability standpoint. 2. Two of the predominant pulmonary surfactants, dipalmitoyl lecithin (DPL) and dipalmitoyl phosphatidylethanolamine (DPPE), were found to inhibit wetting of this synthetic membrane and of human cutaneous epithelium as manifest by a large contact angle. 3. When treated with DPL at physiological concentrations, the porous synthetic membrane was found to support a head of saline well in excess of systolic pulmonary artery pressure with no penetration and could do so for periods well in excess of 1 hr; untreated control samples allowed almost immediate fluid filtration. 4. Filtration could be initiated in the DPL-treated membranes by wetting the reverse side, confirming that the threshold pressure for fluid penetration was afforded by capillarity and, hence, by water repellency induced by the surfactant. 5. Water repellency induced by the amphoteric surfactants occurring naturally in the lung is discussed as a possible factor contributing to the pressure threshold to be exceeded for alveolar oedema to form. 6. Evidence is reviewed and several advantages discussed for the implied concept of an essentially dry lining to the alveolus with a discontinuous liquid layer largely confined to convex corners which could slowly resolve any oedema by surface forces.

  8. Therapeutic surfactant-stripped frozen micelles

    Science.gov (United States)

    Zhang, Yumiao; Song, Wentao; Geng, Jumin; Chitgupi, Upendra; Unsal, Hande; Federizon, Jasmin; Rzayev, Javid; Sukumaran, Dinesh K.; Alexandridis, Paschalis; Lovell, Jonathan F.

    2016-05-01

    Injectable hydrophobic drugs are typically dissolved in surfactants and non-aqueous solvents which can induce negative side-effects. Alternatives like `top-down' fine milling of excipient-free injectable drug suspensions are not yet clinically viable and `bottom-up' self-assembled delivery systems usually substitute one solubilizing excipient for another, bringing new issues to consider. Here, we show that Pluronic (Poloxamer) block copolymers are amenable to low-temperature processing to strip away all free and loosely bound surfactant, leaving behind concentrated, kinetically frozen drug micelles containing minimal solubilizing excipient. This approach was validated for phylloquinone, cyclosporine, testosterone undecanoate, cabazitaxel and seven other bioactive molecules, achieving sizes between 45 and 160 nm and drug to solubilizer molar ratios 2-3 orders of magnitude higher than current formulations. Hypertonic saline or co-loaded cargo was found to prevent aggregation in some cases. Use of surfactant-stripped micelles avoided potential risks associated with other injectable formulations. Mechanistic insights are elucidated and therapeutic dose responses are demonstrated.

  9. 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.

  10. Vapour-liquid equilibrium relationship between toluene and mixed surfactants.

    Science.gov (United States)

    Tian, Senlin; Li, Yingjie; Mo, Hong; Ning, Ping

    2012-01-01

    Micellar partitioning of volatile organic compounds (VOCs) in surfactant solutions and its effects on vapour-liquid equilibrium is fundamental to the overall design and implementation ofsurfactant-enhanced remediation. Knowledge of the vapour-liquid equilibrium partitioning coefficients for VOCs, especially in contaminated soils and groundwater in which they exist, is required. Headspace experiments were performed to quantify the effect of three mixed surfactants, cetyltrimethyl ammonium bromide (CTMAB) with tetrabutylammonium bromide (TBAB), sodium dodecyl sulphate (SDS) with Triton X-405 (TX405), and CTMAB with Triton X-100 (TX100), on the apparent Henry's constants (Hc) of toluene at temperatures ranging from 25 degrees C to 40 degrees C. The Hc values were significantly reduced in the presence of all three mixed surfactants at concentrations above their critical micelle concentrations (CMC). Mixed micellar partitioning, showing effects on the vapour-liquid equilibrium of toluene, was primarily responsible for the significant reduction of Hc in their mixed systems. The mixed surfactants CTMAB-TX100 had the greatest effect on Hc above the CMC, followed by SDS-TX405, then CTMAB-TBAB. Mixed systems of CTMAB-TX100 decreased Hc at concentrations significantly lower than the SDS-TX405 and CTMAB-TBAB concentrations, because of to the lower CMC of CTMAB-TX100. Vapour-liquid equilibrium data were also tested against the model (Hc = H/(1 + K(X - CMC)) that described the partitioning of VOCs in vapour-water-micelle phases. The correlation of Hc with mixed surfactant concentrations (X) and CMC can be utilized as an effective tool to predict the Hc by mixed surfactants.

  11. Surfactant enhanced volumetric sweep efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Harwell, J.H.; Scamehorn, J.F.

    1989-10-01

    Surfactant-enhanced waterflooding is a novel EOR method aimed to improve the volumetric sweep efficiencies in reservoirs. The technique depends upon the ability to induce phase changes in surfactant solutions by mixing with surfactants of opposite charge or with salts of appropriate type. One surfactant or salt solution is injected into the reservoir. It is followed later by injection of another surfactant or salt solution. The sequence of injections is arranged so that the two solutions do not mix until they are into the permeable regions well away from the well bore. When they mix at this point, by design they form a precipitate or gel-like coacervate phase, plugging this permeable region, forcing flow through less permeable regions of the reservoir, improving sweep efficiency. The selectivity of the plugging process is demonstrated by achieving permeability reductions in the high permeable regions of Berea sandstone cores. Strategies were set to obtain a better control over the plug placement and the stability of plugs. A numerical simulator has been developed to investigate the potential increases in oil production of model systems. Furthermore, the hardness tolerance of anionic surfactant solutions is shown to be enhanced by addition of monovalent electrolyte or nonionic surfactants. 34 refs., 32 figs., 8 tabs.

  12. Solubilization of pentanol by cationic surfactants and binary mixtures of cationic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, M.E.

    1993-12-31

    The research reported here has included studies of the solubilization of pentanol in hexadecylpyridinium chloride (CPC), trimethyletetradecylammonium chloride (C{sub 14}Cl), benzyldimethyltetradecylammonium chloride (C{sub 14}BzCl), benzyldimethylhexadecylpyridinium chloride (C{sub 16}BzCl), hexadecyltrimethylammonium bromide (CTAB), and binary mixtures of CPC + C{sub 16}BzCl and C{sub 14}Cl + C{sub 14}BzCl. Rather than using calorimetric methods, this project will employ headspace chromatography to measure solubilization of pentanol over a wide range of solute concentrations. While not yielding as much thermodynamic data as calorimetry, headspace chromatography is a more direct measure of the extent of solubilization. Using headspace chromatography, is a more direct measure of the extent of solubilization. Using headspace chromatography, this study will seek to determine whether strongly synergistic mixture ratios exist in the case of binary cationic surfactant systems. There are two equilibria in the pentanol-water-surfactant system: (1) The pentanol solubilized in micelles is in equilibrium with the monomeric pentanol in solution, and (2) the monomeric pentanol is in equilibrium with the pentanol in the vapor above the solution. To establish the link between the two equilibria, a sample of the vapor above pure liquid pentanol must be collected, in order to find the activity of pentanol in solution. Also, a calibration curve for various concentrations of pentanol in solution. From this type of data it is possible to infer both the concentration of pentanol solubilized in micelles and the concentrations of pentanol in the ``bulk`` solution outside the micelles. The method is equally applicable to systems containing a single surfactant as well as mixtures of surfactants.

  13. DSC study of denaturation of β-lactoglobulin B

    Institute of Scientific and Technical Information of China (English)

    王邦宁; 谈夫

    1995-01-01

    The denaturation of bovine β-lactoglobulin B (β-Lg B) has been studied in phosphate solutions with various concentrations of GuHCl with differential scanning calorimetry The experiments demonstrated that the presence of GuHCl made the β-Lg B undergo both cold denaturation and heat denaturation under the condition of a high concentration of the protein. The enthalpy changes of both kinds of denaturation exhibit opposite signs. Both the cold denaturation and the renaturation of the protein are reproducible, but its heat denaturation is irreversible. The cooperation among monomer molecules of the protein is involved in its heat denaturation The heat denaturation of the protein can be represented by the thermodynamic model Nc D→F. The activation energy of heat denaturation is 285 kJ/mol, which imples that the depression of temperature and enthalpy of heat denaturation of the P-Lg B does not result from decreasing considerably the activation energy by GuHCl As for the cold denaturation of the protein, es

  14. Nano-DTA and nano-DSC with cantilever-type calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Nakabeppu, Osamu, E-mail: onakabep@meiji.ac.jp [Meiji University, School of Science and Technology, Department of Mechanical Engineering, Higashimita 1-1-1, Tama-ku, Kawasaki 214-8571 (Japan); Deno, Kohei [Tokyo Institute of Technology, Graduate School of Science and Engineering, Department of Mechanical Sciences and Engineering (Japan)

    2016-08-10

    Highlights: • Nanocalorimetry with original cantilever type calorimeters. • The calorimeters showed the enthalpy resolution of 200 nJ level. • Nano-DTA of a binary alloy captured a probabilistic peak after solidification. • Power compensation DSC of a microgram level sample was demonstrated. • The DSC and DTA behavior were explained with a lumped model. - Abstract: Differential thermal analysis (DTA) and differential scanning calorimetry (DSC) of the minute samples in the range of microgram to nanogram were studied using original cantilever-type calorimeters. The micro-fabricated calorimeter with a heater and thermal sensors was able to perform a fast temperature scan at above 1000 K/s and a high-resolution heat measurement. The DTA of minuscule metal samples demonstrated some advances such as the thermal analysis of a 20 ng level indium and observation of a strange phase transition of a binary alloy. The power compensation type DSC using a thermal feedback system was also performed. Thermal information of a microgram level sample was observed as splitting into the DSC and DTA signals because of a mismatch between the sample and the calorimeter. Although there remains some room for improvement in terms of the heat flow detection, the behavior of the compensation system in the DSC was theoretically understood through a lumped model. Those experiments also produced some findings, such as a fin effect with sample loading, a measurable weight range, a calibration of the calorimeter and a product design concept. The development of the nano-DTA and nano-DSC will enable breakthroughs for the fast calorimetry of the microscopic size samples.

  15. Evaluation of integrated Raman-DSC technology in early pharmaceutical development: characterization of polymorphic systems.

    Science.gov (United States)

    Huang, Jun; Dali, Manisha

    2013-12-01

    Differential Scanning Calorimetry and Raman spectroscopy are both powerful tools used heavily in pharmaceutical development. For many studies such as polymorph characterization these two techniques are complimentary and provide data on different yet important aspects of material properties when combined together. In this work we describe an integrated Raman-DSC technology that simultaneously generates both DSC thermogram and Raman spectra of the pharmaceutical material being studied. The integrated system consists of a DSC with a Raman fiber optic probe inserted right on top of the sample furnace. The technology integrates synchronized Raman acquisition into DSC scan, enabling collection of molecular and structural information coupled with observation of thermal events. We first establish the technology by optimizing the instrumental set-up that offers relatively high-quality results for simultaneous DSC and Raman data collection. We then demonstrate the application of the technology by studying the polymorphs of d-mannitol, a common pharmaceutical excipient and BMS-A, an investigational drug candidate that exhibits multiple coexisting polymorphs. In both cases, the Raman-DSC technology was able to provide valuable information on the process of phase change and polymorph identification. Although similar information may be obtained by using various characterization techniques together, the integrated Raman-DSC indicated special advantages for industrial development such as high efficiency, material sparing and comprehensive data analysis. Moreover the technology provides an alternative to better correlate real-time phase behavior to molecular understanding. The technology thus has the potential to be used for Process Analytical Technology (PAT) purpose.

  16. Endoplasmic Reticulum Exit of Golgi-resident Defective for SREBP Cleavage (Dsc) E3 Ligase Complex Requires Its Activity.

    Science.gov (United States)

    Raychaudhuri, Sumana; Espenshade, Peter J

    2015-06-01

    Layers of quality control ensure proper protein folding and complex formation prior to exit from the endoplasmic reticulum. The fission yeast Dsc E3 ligase is a Golgi-localized complex required for sterol regulatory element-binding protein (SREBP) transcription factor activation that shows architectural similarity to endoplasmic reticulum-associated degradation E3 ligases. The Dsc E3 ligase consists of five integral membrane proteins (Dsc1-Dsc5) and functionally interacts with the conserved AAA-ATPase Cdc48. Utilizing an in vitro ubiquitination assay, we demonstrated that Dsc1 has ubiquitin E3 ligase activity that requires the E2 ubiquitin-conjugating enzyme Ubc4. Mutations that specifically block Dsc1-Ubc4 interaction prevent SREBP cleavage, indicating that SREBP activation requires Dsc E3 ligase activity. Surprisingly, Golgi localization of the Dsc E3 ligase complex also requires Dsc1 E3 ligase activity. Analysis of Dsc E3 ligase complex formation, glycosylation, and localization indicated that Dsc1 E3 ligase activity is specifically required for endoplasmic reticulum exit of the complex. These results define enzyme activity-dependent sorting as an autoregulatory mechanism for protein trafficking.

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

    Science.gov (United States)

    Vinceković, Marko; Curlin, Marija; Jurašin, Darija

    2014-08-27

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

  18. Self Assembly of Biogenic Surfactants at Mineral Surfaces and Their Effect on Biological Iron Acquisition

    Science.gov (United States)

    Kraemer, S. M.

    2005-12-01

    Microorganisms exude biogenic surfactants to modify the physical and chemical properties of mineral-water interfaces. Surfactants with negatively charged hydrophilic head groups interact strongly with oppositely charged mineral surfaces such as iron or aluminum oxides. Surfactant self assembly at mineral surfaces can result in the formation of admicelles that have a significant effect on the surface charge and hydrophobicity. These effects are exploited by microorganisms to facilitate attachment to mineral surfaces. Similarly, plants exude surfactants into the rhizosphere and change the surface tension and flow of soil water. Other surface active compounds that are typically found in soils and surface waters are humic substances and fatty acids that are produced by degradation of biomass. In general, surface active compounds are ubiquitous in natural systems. In this study we investigated how surfactants influence bio-mineral interactions using the example of siderophore promoted iron acquisition. Siderophore promoted iron acquisition involves the adsorption of a biogenic iron specific ligand (i.e. the siderophore) to iron oxides and the subsequent siderophore promoted iron oxide dissolution. The hypothesis of this project is that the modification of the iron oxide surface charge and hydrophobicity by adsorbed surfactants will have an important effect on siderophore adsorption and dissolution kinetics. We approached this subject by investigating the adsorption of a natural surfactant (rhamnolipids: RhL) and the synthetic surfactant (sodium dodecyl sulfate: SDS) on goethite (α-FeOOH, a common pedogenic iron oxide) and observing the effect of surfactant self assembly on the properties of the mineral water interface. We observed fast adsorption kinetics at pH 3 and slow adsorption at pH 6. The adsorbed surfactants reversed the surface potential of goethite (as evidenced by electrophoretic mobility measurements) at soluble surfactant concentrations below 10 μM (SDS

  19. Surfactants in the gut fluids of Porcellio scaber (Isopoda: Oniscidea), and their interactions with phenolics.

    Science.gov (United States)

    Zimmer, M

    1997-10-01

    Fluids from the gut lumen of Porcellio scaber showed significantly reduced surface tension compared to a buffer solution. Tests with several dilutions indicated that the concentration of the surface active substances (surfactants) was about 80-fold higher than the 'critical micelle concentration'. Phenolics, e.g. gallotannins, when ingested in the diet increased the surface tension of the gut fluid, indicating reduced concentrations of free surfactants. The significance of gut surfactants in P. scaber, their role in digestive processes, and their interaction with tannins in this saprophagous soil arthropod are discussed.

  20. Arbitrary Lagrangian-Eulerian method for computation of impinging droplet with soluble surfactants and dynamic contact angle

    CERN Document Server

    Ganesan, Sashikumaar

    2014-01-01

    An arbitrary Lagrangian--Eulerian (ALE) finite element scheme for computations of soluble surfactant droplet impingement on a horizontal surface is presented. The numerical scheme solves the time-dependent Navier--Stokes equations for the fluid flow, scalar convection-diffusion equation for the surfactant transport in the bulk phase, and simultaneously, surface evolution equations for the surfactants on the free surface and on the liquid-solid interface. The effects of surfactants on the flow dynamics are included into the model through the surfactant-dependent surface tension and dynamic contact angle. In particular, the dynamic contact angle of the droplet is defined as a function of surfactants using the nonlinear equation of state for surface tension. Further, the surface forces are included in the model using the Boussinesq-Scriven law that allows to incorporate the Marangoni effects without evaluating the gradients of surfactant concentration on the free surface. In addition to a mesh convergence study ...

  1. Determination of microplastic polyethylene (PE) and polypropylene (PP) in environmental samples using thermal analysis (TGA-DSC).

    Science.gov (United States)

    Majewsky, Marius; Bitter, Hajo; Eiche, Elisabeth; Horn, Harald

    2016-10-15

    Microplastics are increasingly detected in the environment and the consequences on water resources and ecosystems are not clear to date. The present study provides a cost-effective and straightforward method to determine the mass concentrations of polymer types using thermal analysis. Characteristic endothermic phase transition temperatures were determined for seven plastic polymer types using TGA-DSC. Based on that, extracts from wastewater samples were analyzed. Results showed that among the studied polymers, only PE and PP could be clearly identified, while the phase transition signals of the other polymers largely overlap each other. Subsequently, calibration curves were run for PE and PP for qualitative measurements. 240 and 1540mg/m(3) of solid material (12µm to 1mm) was extracted from two wastewater effluent samples of a municipal WWTP of which 34% (81mg/m(3)) and 17% (257mg/m(3)) could be assigned to PE, while PP was not detected in any of the samples. The presented application of TGA-DSC provides a complementary or alternative method to FT-IR analyses for the determination of PE and PP in environmental samples.

  2. The effects of urea and n-propanol on collagen denaturation: using DSC, circular dicroism and viscosity

    Energy Technology Data Exchange (ETDEWEB)

    Usha, R.; Ramasami, T

    2004-01-30

    The effect of urea and n-propanol on circular dichroism (CD) and viscosity of purified type1 collagen solution at various temperatures and differential scanning calorimetry (DSC) of rat-tail tendon (RTT) collagen fibre have been studied. CD reveals a spectrum with a positive peak at around 220 nm and a negative peak at 200 nm characteristics of collagen triple helix. The molar ellipticity decreases as the concentration of urea increases up to particular concentration (collagen solution treated with 265 {mu}M of urea) and after that it increases (collagen solution treated with 500 {mu}M of urea). There is a linear decrease in molar ellipticity as the concentration of n-propanol increases. Denaturation temperature of urea and n-propanol treated with purified collagen solution has been studied using viscosity method. Additives such as urea and n-propanol decrease the thermal stability of collagen triple helix in solution and in RTT collagen fibre. Thermal helix to coil transition of urea and n-propanol treated collagen depends on the degree of hydration and the concentration of these additives. Thermodynamic parameters such as the peak temperature, enthalpy of activation, and energy of activation for collagen-gelatin transition for native, urea and n-propanol treated RTT collagen fibre has been calculated using DSC. The change in the thermodynamic parameters has been observed for native, urea and n-propanol treated RTT collagen fibres. The experimental results show that the change in the water structure, dehydration and desolvation induced by different additives such as urea and n-propanol on RTT may vary with the type of denaturation.

  3. Surfactant Enhanced Electroremediation of Phenanthrene

    Institute of Scientific and Technical Information of China (English)

    佘鹏; 杨建刚; 等

    2003-01-01

    Removal of hydrophobic organic contaminants(HOCs) form soil of low permeability by electroremediation was investigated by using phenanthrene and kaolinite as a model system.Tween 80 was added into the purging solution in order to enhance the solubility of phenanthrene.The effects of pH on the adsorption of phenanthrene and Tween 80 on kaolinite and the magnitude of ζ-potential of kaolinite were examined,respectively.The effects of electric field strength indicated by electric current on the electroremediation behavior,including the pH of purging solution,the conductivity,phenanthrene concentration and flow rate of effluent,were experimentally investigated,repectively,In case of an electric field of 25mA applied for 72 hours,over 90% of phenanthrene was removed from 424g(dry mass)of kaolinite at an energy consumption of 0.148kW.h.The experimental results described in present study show that the addition of surfactant into purging solution greatly enhances the removel of HOCs by electroremediation.

  4. 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

  5. Biodegradability and toxicity of sulphonate-based surfactants in aerobic and anaerobic aquatic environments.

    Science.gov (United States)

    García, M T; Campos, E; Marsal, A; Ribosa, I

    2009-02-01

    Four types of commonly used sulphonate-based surfactants (alkane sulphonates, alpha-olefin sulphonates, sulphosuccinates and methyl ester sulphonates) were tested for their aerobic and anaerobic biodegradability as well as for their toxicity to Daphnia magna and Photobacterium phosphoreum to assess the effect of the surfactant structure on those properties. Aerobic biodegradation was evaluated by means of the CO2 headspace test and anaerobic biodegradation was assessed by a method based on the ECETOC test. All the surfactants tested were readily biodegraded under aerobic conditions. No clear effect of the surfactant structures on the toxicity to the aquatic organisms tested was found. The most significant differences in the surfactants studied were observed in their behaviour under anaerobic conditions. Alkane sulphonates, alpha-olefin sulphonates and methyl ester sulphonates were not mineralized in lab anaerobic digesters despite the fact that the last one showed a certain degree of primary degradation. Nevertheless, these surfactants did not significantly inhibit methanogenic activity at concentrations up to 15 g surfactant/kg dry sludge, a concentration that is much higher than the expected concentrations of these surfactants in real anaerobic digesters. Sulphosuccinates showed a high level of primary biodegradation in anaerobic conditions. However, linear alkyl sulphosuccinates were completely mineralized whereas branched alkyl sulphosuccinates achieved percentages of ultimate biodegradation < or =50%.

  6. 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

    2017-03-03

    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.

  7. 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 metabol

  8. Comparative study by TG and DSC Of membranes polyamide66/bentonite clay nanocomposite; Estudo comparativo por TG e DSC de membranas de nanocompositos poliamida66/argila bentonitica

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, K.M. de; Kojuch, L.R.; Araujo, E.M.; Lira, H.L., E-mail: keilamm@ig.com.b [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Lima, F. [Universidade Estadual da Paraiba (UEPB), Campina Grande, PB (Brazil). Dept. de Quimica

    2010-07-01

    In this study, it was obtained membranes of nanocomposites polyamide66 with 3 and 5% bentonite clay consists of silicates in layers from the interior of Paraiba. The clay was treated with a quaternary ammonium salt in order to make it organophilic. The membranes were prepared by phase inversion technique from the nanocomposites in solution. The clays were characterized by X-ray diffraction (XRD) and thermogravimetry (TG). Also the membranes were characterized by differential scanning calorimetry (DSC) and TG. The XRD and TG confirmed the presence of salt in the clay and thermal stability of the treated clay. For DSC, it was observed that there was no change in melting temperature of the membranes of nanocomposites compared to membrane pure polyamide66. By TG, it was found that the decomposition of the membranes of polyamide66 with treated clay were higher compared with the untreated clay. (author)

  9. Electrochemical Oscillations Induced by Surfactants

    Institute of Scientific and Technical Information of China (English)

    翟俊红; 贺占博

    2003-01-01

    A new type of electrochemical oscillation induced by surfactant was observed in experiments. The electrochemical system is a Daniell cell with a copper rod in CuSO4 aqueous and an aluminum rod in Al(NO3)3 aqueous as electrodes. The surfactants are CTAB, TX-100, SLS. The addition of trace surfactant solution by a micro-syringe made the original monotonously changing electrochemical system produce obvious periodic phenomena. At the mean time, the copper ion selective electrode and Hg2SO4 reference electrode were used to monitor the copper electrode reaction and determine its rate constant k of first order reaction. According to the experimental results of electrode reaction kinetics, the possible mechanism was found to be the polarization induced from the directional adsorption of trace surfactant on the electrode surface. That is the electrochemical oscillations.

  10. Emulsification at the Liquid/Liquid Interface: Effects of Potential, Electrolytes and Surfactants.

    Science.gov (United States)

    Chowdhury, Mehrin; Kataky, Ritu

    2016-01-04

    Emulsification of oils at liquid/liquid interfaces is of fundamental importance across a range of applications, including detergency. Adsorption and partitioning of the anionic surface active ions at the interface between two immiscible solutions is known to cause predictable chaos at the transfer potential region of the surfactant. In this work, the phenomenon that leads to the chaotic behaviour shown by sodium dodecylbenzene sulfonate (SDBS) at the water/1,2-dichloroethane interface is applied to commercial surfactants and aqueous/glyceryl trioleate interface. Electrochemical methods, electrocapillary curves, optical microscopy and conductivity measurements demonstrated that at 1.5 mm of SDBS, surfactants are adsorbed at the interface and assemble into micelles, leading to interfacial instability. As the concentration of the anionic surfactant was enhanced to 8 and 13.4 mm, the Marangoni effect and the interfacial emulsification became more prominent. The chaotic behaviour was found to be dependent on the surfactant concentration and the electrolytes present.

  11. Stratum corneum lipid removal by surfactants: relation to in vivo irritation.

    Science.gov (United States)

    Froebe, C L; Simion, F A; Rhein, L D; Cagan, R H; Kligman, A

    1990-01-01

    The relationship between the in vivo irritation potential of sodium lauryl sulfate (SLS) and linear alkyl benzene sulfonate (LAS) and the ability of these two surfactants to remove lipid from the stratum corneum (SC) in vitro were investigated. Either surfactant removes detectable levels of lipids only above its critical micelle concentration (CMC). At high concentrations the surfactants removed only very small amounts of cholesterol, free fatty acid, the esters of those materials, and possibly squalene. SLS and LAS have been shown, below the CMC, to bind to and irritate the SC. Thus, clinical irritation provoked by SLS or LAS is unlikely to be directly linked with extraction of SC lipid. The milder forms of irritation--dryness, tightness, roughness--may involve both surfactant binding to and denaturation of keratin as well as disruption of lipid. Our findings challenge earlier assumptions that surfactants' degreasing of the SC is involved in the induction of erythema.

  12. The Effects of Periodic Wall Stretch on Surfactant and Liquid Transport

    Science.gov (United States)

    Bull, Joseph; Halpern, David; Grotberg, James

    1999-11-01

    The cycle-mean transport of soluble surfactant and airway surface liquid is examined using a mathematical model of Marangoni flows which accounts for airway branching and for time-periodic radial and axial airway stretch. The transport of surfactant and liquid is fundamental to surfactant replacement therapy as well as liquid and surfactant clearance from healthy lungs. The majority of surfactant and liquid transport occurs in the cycle-mean spreading which follows the very brief initial transient spreading phase. We consider either delivery of surfactants into the lung, by setting the proximal boundary condition to a higher concentration compared to the distal boundary condition, or removal from the lung by switching these end conditions. Starting with a steady-state, non-cycled, non-uniform, surfactant distribution we find that transport of surfactant into the lung is enhanced for larger strain amplitudes and frequency, though frequency is less important. For surfactant clearance from the lung we find, as in the case of delivery, that larger strain amplitude enhances transport. But, cycling frequency has the opposite effect with larger frequencies leading to reduced transport. Liquid clearance is enhanced by larger strain amplitudes and slower frequencies. This work supported by NIH grant HL-41126 and NSF grant CTS-9412523.

  13. Solubilization and degradation of perchloroethylene (PCE) in cationic and nonionic surfactant solutions

    Institute of Scientific and Technical Information of China (English)

    Sivaram Harendra; Cumaraswamy Vipulanandan

    2011-01-01

    Solubilization of perchloroethylene (PCE) in a nonionic (Triton X-100) and a cationic (cetyltrimethylammonium bromide (CTAB)) surfactant solutions and the degradation of surfactant solubilized PCE using fine to nanosize Fe and bi-metallic Fe-Ni particles were investigated.Micelle partition coefficients (Km) and molar solubility ratio (MSR) for PCE in 10 g/L of surfactant solutions have been quantified and the solubility of PCE (100 mg/L in water) in the surfactant solutions increased by about ten fold.Of the two surfactants studied,Triton X-100 solubilized the higher amount of PCE per gram of surfactant.To degrade solubilized PCE,both iron and bimetallic Fe-Ni particles were used in continuously stirred batch reactors.The iron and bi-metallic particles were synthesized using the solution method and the particles were characterized using the SEM,EDS,TEM and XRD.The PCE solubilized up to 500 mg/L in both surfactant solutions were totally degraded at various rates by 200 g/L of bi-metallic Fe-Ni particles in less than 20 hr,which is the highest concentration of PCE degraded in the shortest time compared to data in the literature.The degradations of PCE solubilized in surfactant solutions were represented by nonlinear kinetic relationships which depended on the type of surfactant used for solubilizing the PCE.

  14. Fast-Scan DSC and its role in pharmaceutical physical form characterisation and selection.

    Science.gov (United States)

    Ford, James L; Mann, Timothy E

    2012-04-01

    Conventional rate Differential Scanning Calorimetry (DSC) has been used for many years as a tool in the analysis of pharmaceutical materials. In recent years an extension of the technique to include fast heating and cooling rates has become more prevalent. Broadly termed Fast-Scan DSC, this review examines the current applications of this technique to the characterisation and selection of pharmaceutical materials. Its increasing use encompasses the characterisation of amorphousness in crystalline materials, the characterisation of polymorphs and polymorphic transitions, the solubility of drugs in polymers, and characterisation of dosage forms. Notwithstanding the advantages of analytical speed in analytical turnover, the review emphasises the advantages of Fast-Scan DSC in its sensitivity which allows the separation of overlapping thermal events, the reduction it provides in degradation during the scanning process and its role in determining solubility in waxy and polymeric based systems. A comparison of the uses of Fast-Scan DSC to modulated DSC techniques and localised thermal analysis is also given.

  15. DSC: software tool for simulation-based design of control strategies applied to wastewater treatment plants.

    Science.gov (United States)

    Ruano, M V; Ribes, J; Seco, A; Ferrer, J

    2011-01-01

    This paper presents a computer tool called DSC (Simulation based Controllers Design) that enables an easy design of control systems and strategies applied to wastewater treatment plants. Although the control systems are developed and evaluated by simulation, this tool aims to facilitate the direct implementation of the designed control system to the PC of the full-scale WWTP (wastewater treatment plants). The designed control system can be programmed in a dedicated control application and can be connected to either the simulation software or the SCADA of the plant. To this end, the developed DSC incorporates an OPC server (OLE for process control) which facilitates an open-standard communication protocol for different industrial process applications. The potential capabilities of the DSC tool are illustrated through the example of a full-scale application. An aeration control system applied to a nutrient removing WWTP was designed, tuned and evaluated with the DSC tool before its implementation in the full scale plant. The control parameters obtained by simulation were suitable for the full scale plant with only few modifications to improve the control performance. With the DSC tool, the control systems performance can be easily evaluated by simulation. Once developed and tuned by simulation, the control systems can be directly applied to the full-scale WWTP.

  16. Yeast SREBP cleavage activation requires the Golgi Dsc E3 ligase complex.

    Science.gov (United States)

    Stewart, Emerson V; Nwosu, Christine C; Tong, Zongtian; Roguev, Assen; Cummins, Timothy D; Kim, Dong-Uk; Hayles, Jacqueline; Park, Han-Oh; Hoe, Kwang-Lae; Powell, David W; Krogan, Nevan J; Espenshade, Peter J

    2011-04-22

    Mammalian lipid homeostasis requires proteolytic activation of membrane-bound sterol regulatory element binding protein (SREBP) transcription factors through sequential action of the Golgi Site-1 and Site-2 proteases. Here we report that while SREBP function is conserved in fungi, fission yeast employs a different mechanism for SREBP cleavage. Using genetics and biochemistry, we identified four genes defective for SREBP cleavage, dsc1-4, encoding components of a transmembrane Golgi E3 ligase complex with structural homology to the Hrd1 E3 ligase complex involved in endoplasmic reticulum-associated degradation. The Dsc complex binds SREBP and cleavage requires components of the ubiquitin-proteasome pathway: the E2-conjugating enzyme Ubc4, the Dsc1 RING E3 ligase, and the proteasome. dsc mutants display conserved aggravating genetic interactions with components of the multivesicular body pathway in fission yeast and budding yeast, which lacks SREBP. Together, these data suggest that the Golgi Dsc E3 ligase complex functions in a post-ER pathway for protein degradation.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-09-26

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-11-01

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

  19. Mechanistic study of wettability alteration of oil-wet sandstone surface using different surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Bao-feng, E-mail: hbf370283@163.com; Wang, Ye-fei; Huang, Yong

    2015-03-01

    Graphical abstract: Zeta potential of oil-wet quartz powder treated with different surfactants at different concentrations. - Highlights: • Mechanisms of wettability alteration during surfactant flooding were studied. • Different analytical instruments were used to study sandstone wettability alteration. • Surfactants’ structure plays a great role in wettability alteration of solid surface. • CTAB irreversibly desorbs carboxylic acid from solid surface by ionic interaction. • Cationic surfactant is more effective in wettability alteration of sandstone surface. - Abstract: Different analytical methods including Fourier transform infrared (FTIR), atomic force microscopy (AFM), zeta potential measurements, contact angle measurements and spontaneous imbibition tests were utilized to make clear the mechanism for wettability alteration of oil-wet sandstone surface using different surfactants. Results show that among three types of surfactants including cationic surfactants, anionic surfactants and nonionic surfactants, the cationic surfactant CTAB demonstrates the best effect on the wettability alteration of oil-wet sandstone surface. The positively charged head groups of CTAB molecules and carboxylic acid groups from crude oil could interact to form ion pairs, which could be desorbed from the solid surface and solubilized into the micelle formed by CTAB. Thus, the water-wetness of the solid surface is improved. Nonionic surfactant TX-100 could be adsorbed on oil-wet sandstone surface through hydrogen bonds and hydrophobic interaction to alter the wettability of oil-wet solid surface. The wettability alteration of oil-wet sandstone surface using the anionic surfactant POE(1) is caused by hydrophobic interaction. Due to the electrostatic repulsion between the anionic surfactant and the negatively charged surface, POE(1) shows less effect on the wettability alteration of oil-wet sandstone surface.

  20. 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.

  1. 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.

  2. Development of novel sustained release matrix pellets of betahistine dihydrochloride: effect of lipophilic surfactants and co-surfactants.

    Science.gov (United States)

    Shamma, Rehab Nabil; Basalious, Emad B; Shoukri, Raguia

    2012-01-01

    Sustained release matrix pellets of the freely water soluble drug, betahistine dihydrochloride (BH), were prepared using freeze pelletization technique. Different waxes and lipids (cetyl alcohol, beeswax, glyceryl tripalmitate (GTP) and glyceryl tristearate) were evaluated for the preparation of matrix pellets. A D-optimal design was employed for the optimization and to explore the effect of drug loading (X(1)), concentration of lipophilic surfactant (X(2)), concentration of co-surfactant (X(3)) and wax type (X(4)) on the release extent of the drug from matrix pellets. The entrapment efficiency (Y(1)), pellet diameter (Y(2)), and the percentage drug released at given times were selected as dependent variables. Results revealed a significant impact of all independent variables on drug release from the formulated pellets. The lipophilic surfactant significantly increased both the entrapment efficiency and the in vitro drug release and significantly decreased the pellet size. The optimized BH-loaded pellets were composed of 19.95% drug loading, 9.95% Span(®) 80 (surfactant), 0.25% Capmul(®) (co-surfactant) using glyceryl tripalmitate as a matrix former. The release profiles of the drug from hard gelatin capsule containing optimized pellets equivalent to 32 mg BH was similar to that of target release model for once-daily administration based on similarity factor. It could be concluded that a promising once-daily capsule containing sustained release pellets of BH was successfully designed.

  3. Size separation of analytes using monomeric surfactants

    Science.gov (United States)

    Yeung, Edward S.; Wei, Wei

    2005-04-12

    A sieving medium for use in the separation of analytes in a sample containing at least one such analyte comprises a monomeric non-ionic surfactant of the of the general formula, B-A, wherein A is a hydrophilic moiety and B is a hydrophobic moiety, present in a solvent at a concentration forming a self-assembled micelle configuration under selected conditions and having an aggregation number providing an equivalent weight capable of effecting the size separation of the sample solution so as to resolve a target analyte(s) in a solution containing the same, the size separation taking place in a chromatography or electrophoresis separation system.

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

    OpenAIRE

    2012-01-01

    PURPOSE: Exogenous surfactant is not very effective in adults with ARDS, since surfactant does not reach atelectatic alveoli. Perfluorocarbons (PFC) can recruit atelectatic areas but do not replace impaired endogenous surfactant. A surfactant-PFC-mixture could combine benefits of both therapies. The aim of the proof-of-principal-study was to produce a PFC-in-surfactant emulsion (Persurf) and to test in surfactant depleted Wistar rats whether Persurf achieves I.) a more homogenous pulmonary di...

  5. Estimation of hydrogen bondings in coal utilizing FTir and differential scanning calorimetry (DSC); FTir to DSC wo mochiita sekitannai suiso ketsugo no teiryoteki hyoka no kokoromi

    Energy Technology Data Exchange (ETDEWEB)

    Mae, K.; Miura, K. [Kyoto University, Kyoto (Japan). Faculty of Engineering

    1996-10-28

    With an objective to know coal condensation structure which has influence on coal conversion reaction, an attempt was made on quantitative evaluation of hydrogen bonding in coal. Using as test samples the VDC made from Taiheiyo coal swollen by tetralin and vacuum-dried, and its pyrolyzed char, DSC measurement and Fourier transform infrared spectroscopy (FT) were performed. An FT spectrum comparison revealed that the VDC swollen at 220{degree}C has the hydrogen bonding relaxed partly from the original coal. However, since the change is in a huge coal molecular structure restraining space, it has stopped at relaxation of the bonding energy without causing separation as far as free radicals. On the other hand, the DSC curve shows that the VDC has slower endothermic velocity than the original coal. In other words, the difference in heat absorption amounts in both materials is equivalent to the difference of enthalpy ({Delta} H) of both materials, which corresponds to the relaxation of the hydrogen bonding. Therefore, the {Delta} H was related to wavenumber shift of the FT spectra (which corresponds to change in the hydrogen bonding condition). By using this relationship, a method for evaluating hydrogen bonding distribution was proposed from an O-H contracting vibration change that can be measured by using the FT spectra and a thermal change that can be measured by using the DSC. 3 refs., 7 figs.

  6. [Study on the Effects of Ginsenoside Rb1 on DPPC Bilayers by Using Thermo-Raman Spectrum and DSC].

    Science.gov (United States)

    Hui, Ge; Liu, Wei; Zhang, Jing-zhou; Zhou, Tie-li; Wang, Si-ming; Zhao, Yu; Zhao, Bing

    2015-08-01

    The research on the interactions between Ginsenosides and biomembranes plays a crucial role in thorough understanding the pharmacological activity and biologyical effect of Chinese medicine Panax ginseng. With the bilayer structure, DPPC often serves as an simulation model of the cell membrane to study the role of drug molecules and cell membranes. Ginsenoside Rb1, one of the most important components of Panaxginseng, playing the significant roles of pharmacological effects and biological properties. Raman and differential scanning calorimetry (DSC) are respectively a powerful tool for discussing the molecular interaction, and a kind of general technology by which researching the bilayer monomer structures and its interactions with drug molecules. However, rarely research reports on the interactions between drug molecules and biomembranes by means of both technologies above. In this paper, the influence of ginsenoside monomer Rb1 on DPPC membrane bilayers was investigated by thermo-Raman and DSC. In Raman spectra, the changes of DPPC molecule have been observed before and after interacted with ginsenoside Rb1, the data analysis indicates three aspects: the O-C-C-N+ polar head group skeleton, C-C stretching vibration area, and the C-H bond stretching vibrarion in terminated methyl group of alkyl chains. The results showed that ginsenoside Rb1 molecule with certain concentration has not changed the gauche conformation of the polar head backbone group in DPPC bilayers, the order of the internal molecular chain and the lateral chain-chain packing have been decreased as the temperature increased, the lateral disposed disorder has been increased. The changes of some thermodynamic constants obtained by DSC experiment such as phase transition temperature (Tm), the temperature at which the transition is half completed (ΔT1/2), and the transition enthalpy normalized per mol of DPPC (AH) have been showed further results of the thermo Raman experiments, with increasing the

  7. Dielectrophoresis of a surfactant-laden viscous drop

    Science.gov (United States)

    Mandal, Shubhadeep; Bandopadhyay, Aditya; Chakraborty, Suman

    2016-06-01

    The dielectrophoresis of a surfactant-laden viscous drop in the presence of non-uniform DC electric field is investigated analytically and numerically. Considering the presence of bulk-insoluble surfactants at the drop interface, we first perform asymptotic solution for both low and high surface Péclet numbers, where the surface Péclet number signifies the strength of surface convection of surfactants as compared to the diffusion at the drop interface. Neglecting fluid inertia and interfacial charge convection effects, we obtain explicit expression for dielectrophoretic drop velocity for low and high Péclet numbers by assuming small deviation of drop shape from sphericity and small deviation of surfactant concentration from the equilibrium uniform distribution. We then depict a numerical solution, assuming spherical drop, for arbitrary values of Péclet number. Our analyses demonstrate that the asymptotic solution shows excellent agreement with the numerical solution in the limiting conditions of low and high Péclet numbers. The present analysis shows that the flow-induced redistribution of the surfactants at the drop interface generates Marangoni stress, owing to the influence of the surfactant distribution on the local interfacial tension, at the drop interface and significantly alters the drop velocity at steady state. For a perfectly conducting/dielectric drop suspended in perfectly dielectric medium, Marangoni stress always retards the dielectrophoretic velocity of the drop as compared with a surfactant-free drop. For a leaky dielectric drop suspended in another leaky dielectric medium, in the low Péclet number limit, depending on the electrical conductivity and permittivity of both the liquids, the Marangoni stress may aid or retard the dielectrophoretic velocity of the drop. The Marangoni stress also has the ability to move the drop in the opposite direction as compared with a surfactant-free drop. This non-intuitive reverse motion of the drop is

  8. Effect of a commercial alcohol ethoxylate surfactant (C11-15E7) on biodegradation of phenanthrene in a saline water medium by Neptunomonas naphthovorans.

    Science.gov (United States)

    Li, Jing-Liang; Bai, Renbi

    2005-02-01

    Biodegradation of poorly soluble polycyclic aromatic hydrocarbons (PAHs) has been a challenge in bioremediation. In recent years, surfactant-enhanced bioremediation of PAH contaminants has attracted great attention in research. In this study, biodegradation of phenanthrene as a model PAHs solubilized in saline micellar solutions of a biodegradable commercial alcohol ethoxylate nonionic surfactant was investigated. The critical micelle concentration (CMC) of the surfactant and its solubilization capacity for phenanthrene were examined in an artificial saline water medium, and a type of marine bacteria, Neptunomonas naphthovorans, was studied for the biodegradation of phenanthrene solubilized in the surfactant micellar solutions of the saline medium. It is found that the solubility of phenanthrene in the surfactant micellar solutions increased linearly with the surfactant concentrations, but, at a fixed phenanthrene concentration, the biodegradability of phenanthrene in the micellar solutions decreased with the increase of the surfactant concentrations. This was attributed to the reduced bioavailability of phenanthrene, due to its increased solubilization extent in the micellar phase and possibly lowered mass transfer rate from the micellar phase into the aqueous phase or into the bacterial cells. In addition, an inhibitory effect of the surfactant on the bacterial growth at high surfactant concentrations may also play a role. It is concluded that the surfactant largely enhanced the solubilization of phenanthrene in the saline water medium, but excess existence of the surfactant in the medium should be minimized or avoided for the biodegradation of phenanthrene by Neptunomonas naphthovorans.

  9. Effect of surfactant hydrophile-lipophile balance (HLB) value on mineral oxide charging in apolar media.

    Science.gov (United States)

    Gacek, Matthew Michael; Berg, John C

    2015-07-01

    The current work examines the role of surfactant hydrophile-lipophile balance (HLB) on the ability for surfactant reverse micelles to impart charge to particles dispersed in an apolar medium, a study motivated by a number of applications that seek to maximize particle charge in such systems. Previous investigations have shown that relative acid-base properties of the particles and surfactants, as well as surfactant concentration and trace water content, all play a major role in the particle charge obtained. However, the ability of a surfactant to stabilize charge in reverse micelles is also an important aspect of creating charge on a particle surface. It has been previously shown that surfactant HLB value is an important parameter in assessing the size of the polar core of the reverse micelles, thereby impacting the total charge that is generated in the bulk solution as determined by conductivity. In the current study, this theory is extended to investigate the impact on particle charging. To accomplish this, the electrophoretic mobility is determined for a series of mineral oxides dispersed in Isopar-L with either Span 20, Span 80, or Span 85. These three surfactants all have the same head group chemistry, but their HLB value ranges from 1.8 to 8.6. It is found that the maximum observed particle electrophoretic mobility does scale directly with the HLB of the accompanying surfactant. This indicates that there is a direct correlation between a surfactant's ability to stabilize charge and its ability to impart charge to a particle. However, the largest HLB surfactant, Span 20, also exhibited a large amount of charge screening or neutralization at larger surfactant concentrations. This highlights the competition between particle charging and micelle-micelle charging that remains one of the largest obstacles to maximizing particle charge in apolar systems.

  10. Evaporation of Sessile Droplets Laden with Particles and Insoluble Surfactants.

    Science.gov (United States)

    Karapetsas, George; Chandra Sahu, Kirti; Matar, Omar K

    2016-07-12

    We consider the flow dynamics of a thin evaporating droplet in the presence of an insoluble surfactant and noninteracting particles in the bulk. On the basis of lubrication theory, we derive a set of evolution equations for the film height, the interfacial surfactant, and bulk particle concentrations, taking into account the dependence of liquid viscosity on the local particle concentration. An important ingredient of our model is that it takes into account the fact that the surfactant adsorbed at the interface hinders evaporation. We perform a parametric study to investigate how the presence of surfactants affects the evaporation process as well as the flow dynamics with and without the presence of particles in the bulk. Our numerical calculations show that the droplet lifetime is affected significantly by the balance between the ability of the surfactant to enhance spreading, suppressing the effect of thermal Marangoni stresses-induced motion, and to hinder the evaporation flux through the reduction of the effective interfacial area of evaporation, which tend to accelerate and decelerate the evaporation process, respectively. For particle-laden droplets and in the case of dilute solutions, the droplet lifetime is found to be weakly dependent on the initial particle concentration. We also show that the particle deposition patterns are influenced strongly by the direct effect of the surfactant on the evaporative flux; in certain cases, the "coffee-stain" effect is enhanced significantly. A discussion of the delicate interplay between the effects of capillary pressure and solutal and thermal Marangoni stresses, which drive the liquid flow inside of the evaporating droplet giving rise to the observed results, is provided herein.

  11. Evaporation of droplets of surfactant solutions.

    Science.gov (United States)

    Semenov, Sergey; Trybala, Anna; Agogo, Hezekiah; Kovalchuk, Nina; Ortega, Francisco; Rubio, Ramón G; Starov, Víctor M; Velarde, Manuel G

    2013-08-13

    The simultaneous spreading and evaporation of droplets of aqueous trisiloxane (superspreader) solutions onto a hydrophobic substrate has been studied both experimentally, using a video-microscopy technique, and theoretically. The experiments have been carried out over a wide range of surfactant concentration, temperature, and relative humidity. Similar to pure liquids, four different stages have been observed: the initial one corresponds to spreading until the contact angle, θ, reaches the value of the static advancing contact angle, θad. Duration of this stage is rather short, and the evaporation during this stage can be neglected. The evaporation is essential during the next three stages. The next stage after the spreading, which is referred to herein as the first stage, takes place at constant perimeter and ends when θ reaches the static receding contact angle, θr. During the next, second stage, the perimeter decreases at constant contact angle θ = θr for surfactant concentration above the critical wetting concentration (CWC). The static receding contact angle decreases during the second stage for concentrations below CWC because the concentration increases due to the evaporation. During the final stage both the perimeter and the contact angle decrease. In what follows, we consider only the longest stages I and II. The developed theory predicts universal curves for the contact angle dependency on time during the first stage, and for the droplet perimeter on time during the second stage. A very good agreement between theory and experimental data has been found for the first stage of evaporation, and for the second stage for concentrations above CWC; however, some deviations were found for concentrations below CWC.

  12. Evaluation of the modified nanoclay effect on the vulcanization of SBR through rheometric curve and DSC;Avaliacao do efeito de nanoargila modificada na vulcanizacao de SBR atraves da curva reometrica e DSC

    Energy Technology Data Exchange (ETDEWEB)

    Forte, Maria Madalena C.; Brito, Karin J.S., E-mail: mmcforte@ufrgs.b [Universidade Federal do Rio Grande do Sul (PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica; Gheller Junior, Jordao [SENAI, Sao Leopoldo, RS (Brazil). Centro Tecnologico de Polimeros

    2009-07-01

    Rubber nanocomposites with nanoclays organically modified by quaternary ammonium salts may have the curing features modified significantly, since the salts may act on the rubber cure system. The aim of this work is to evaluate the influences of an organically modified montmorillonite (OMMT) on the curing reaction of an SBR (styrene butadiene rubber) with sulfur. The SBR/OMMT nanocomposites were prepared by co-coagulating SBR latex and Cloisite{sup R} 20A aqueous suspension at different nanoclay concentrations. The OMMT effect on the sulfur curing reaction was evaluated by the rheometric curve using a rheometer type RPA (Rubber Process Analyzer) and the heat of vulcanization (DELTAH{sub v}) using Differential Scanning Calorimetry (DSC). The evaluation of the clay nanolayers dispersion in the SBR matrix was accomplished by x-ray diffraction (XRD) analysis. (author)

  13. The Determination of Anionic Surfactants in Natural and Waste Waters.

    Science.gov (United States)

    Crisp, P. T.; And Others

    1983-01-01

    Background information, procedures, and results of an experiment suitable for measuring subpart per million concentrations of anionic surfactants in natural waters and waste effluents are provided. The experiment required only a spectrophotometer or filter photometer and has been successfully performed by students in an undergraduate environmental…

  14. The Determination of Anionic Surfactants in Natural and Waste Waters.

    Science.gov (United States)

    Crisp, P. T.; And Others

    1983-01-01

    Background information, procedures, and results of an experiment suitable for measuring subpart per million concentrations of anionic surfactants in natural waters and waste effluents are provided. The experiment required only a spectrophotometer or filter photometer and has been successfully performed by students in an undergraduate environmental…

  15. Phase behavior and shear alignment in SWNT-surfactant dispersions.

    Science.gov (United States)

    Nativ-Roth, Einat; Yerushalmi-Rozen, Rachel; Regev, Oren

    2008-09-01

    The effect of single-walled carbon nanotubes (SWNT) on the phase behavior of the cationic surfactant cetyltrimethylammonium bromide (CTAB) in aqueous solutions is investigated at room temperature. Small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM) are used for characterization of bulk dispersions and nanometrically thin films. Additional carbonaceous additives (fullerenes, multi-walled carbon nanotubes, and carbon black) serve as reference systems. It is found that dispersions of carbonaceous additive (excluding fullerenes) at intermediate surfactant concentrations (below the liquid-crystalline region of the native surfactant) induce demixing and macroscopic phase separation in otherwise homogeneous solutions of CTAB. Two coexisting liquid phases of similar CTAB concentrations are observed, with the carbonaceous species residing within the lower phase. At high CTAB concentrations (liquid-crystal region) the SWNTs are found to incorporate into the ordered lyotropic liquid-crystalline phase while preserving the native d-spacing. Investigation of nanometrically thin films at intermediate surfactant concentrations under external shear reveals shear-induced structure (SIS) in the presence of minute amounts of SWNTs. The effect is found to be exclusive to SWNT and does not occur in dispersions of other carbonaceous additives.

  16. 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

  17. Marangoni Effects of a Drop in an Extensional Flow: The Role of Surfactant Physical Chemistry

    Science.gov (United States)

    Stebe, Kathleen J.; Balasubramaniam, R. (Technical Monitor)

    2002-01-01

    While the changes in stresses caused by surfactant adsorption on non-deforming interfaces have been fairly well established, prior to this work, there were few studies addressing how surfactants alter stresses on strongly deforming interfaces. We chose the model problem of a drop in a uniaxial extensional flow to study these stress conditions To model surfactant effects at fluid interfaces, a proper description of the dependence of the surface tension on surface concentration, the surface equation of state, is required. We have adopted a surface equation of state that accounts for the maximum coverage limit; that is, because surfactants have a finite cross sectional area, there is an upper bound to the amount of surfactant that can adsorb in a monolayer. The surface tension reduces strongly only when this maximum coverage is approached. Since the Marangoni stresses go as the derivative of the surface equation of state times the surface concentration gradient, the non-linear equation of state determines both the effect of surfactants in the normal stress jump, (which is balanced by the product of the mean curvature of the interface times the surface tension), and the tangential stress jump, which is balanced by Marangoni stresses. First, the effects of surface coverage and intermolecular interactions among surfactants which drive aggregation of surfactants in the interface were studied. (see Pawar and Stebe, Physics of Fluids).

  18. Desorption of two organophosphorous pesticides from soil with wastewater and surfactant solutions.

    Science.gov (United States)

    Hernández-Soriano, M C; Mingorance, M D; Peña, A

    2012-03-01

    A batch test was used to evaluate the extent of desorption of diazinon and dimethoate, preadsorbed on a calcareous agricultural soil, representative of the Mediterranean area. Urban wastewater from a secondary treatment and seven surfactant solutions, at concentrations ranging from 0.75 mg L(-1) to 10 gL(-1), were used. The surfactants assayed were cationic (hexadecyl trimethyl ammonium bromide (HD)), anionic (sodium dodecyl sulfate (SDS), Aerosol 22 (A22) and Biopower (BP)), and nonionic (Tween 80 (TW), Triton X 100 (TX) and Glucopon 600 (G600)). Desorption of dimethoate was either not affected or only slightly by the nonionic and anionic surfactants tested, while desorption of diazinon from the soil was only enhanced by A22, BP and TW. This desorption increase correlated significantly with the surfactant concentration of the solution used for desorption and with the concurrent increase in the supernatant of the dissolved organic carbon, in particular that originating from the surfactant. This parameter did not vary with the use of SDS, G600 and TX. The cationic surfactant HD was retained on the soil surface, as confirmed by an increase in soil organic carbon, resulting in a fall in desorption rate for both pesticides. Comparing treatment by wastewater with control water, there was no difference in desorption rate for either pesticide. Mixed TW/anionic surfactant solutions either did not modify or slightly increased desorption of both pesticides in comparison with individual surfactant solutions.

  19. Surfactant and metal ion effects on the mechanical properties of alginate hydrogels.

    Science.gov (United States)

    Kaygusuz, Hakan; Evingür, Gülşen Akın; Pekcan, Önder; von Klitzing, Regine; Erim, F Bedia

    2016-11-01

    This paper addresses the controlled variation of the mechanical properties of alginate gel beads by changing the alginate concentration or by adding different surfactants or cross-linking cations. Alginate beads containing nonionic Brij 35 or anionic sodium dodecyl sulfate (SDS) surfactants were prepared with two different types of cations (Ca(2+), Ba(2+)) as crosslinkers. Compression measurements were performed to investigate the effect of the surfactant and cation types and their concentrations on the Young's modulus of alginate beads. The Young's modulus was determined by using Hertz theory. For all types of alginate gel beads the Young's modulus showed an increasing value for increasing alginate contents. Addition of the anionic surfactant SDS increases the Young's modulus of the alginate beads while the addition of non-ionic surfactant Brij 35 leads to a decrease in Young's modulus. This opposite behavior is related to the contrary effect of both surfactants on the charge of the alginate beads. When Ba(2+) ions were used as crosslinker cation, the Young's modulus of the beads with the surfactant SDS was found to be approximately two times higher than the modulus of beads with the surfactant Brij 35. An ion specific effect was found for the crosslinking ability of divalent cations.

  20. Enhancing plant-microbe associated bioremediation of phenanthrene and pyrene contaminated soil by SDBS-Tween 80 mixed surfactants.

    Science.gov (United States)

    Ni, Hewei; Zhou, Wenjun; Zhu, Lizhong

    2014-05-01

    The use of surfactants to enhance plant-microbe associated dissipation in soils contaminated with polycyclic aromatic hydrocarbons (PAHs) is a promising bioremediation technology. This comparative study was conducted on the effects of plant-microbe treatment on the removal of phenanthrene and pyrene from contaminated soil, in the presence of low concentration single anionic, nonionic and anionic-nonionic mixed surfactants. Sodium dodecyl benzene sulfonate (SDBS) and Tween 80 were chosen as representative anionic and nonionic surfactants, respectively. We found that mixed surfactants with concentrations less than 150 mg/kg were more effective in promoting plant-microbe associated bioremediation than the same amount of single surfactants. Only about (m/m) of mixed surfactants was needed to remove the same amount of phenanthrene and pyrene from either the planted or unplanted soils, when compared to Tween 80. Mixed surfactants (Tween 80. These results may be explained by the lower sorption loss and reduced interfacial tension of mixed surfactants relative to Tween 80, which enhanced the bioavailability of PAHs in soil and the microbial degradation efficiency. The higher remediation efficiency of low dosage SDBS-Tween 80 mixed surfactants thus advanced the technology of surfactant-enhanced plant-microbe associated bioremediation.

  1. Novel Piperazine-based Gemini and Bola Surfactants

    Institute of Scientific and Technical Information of China (English)

    Qing Shan ZHANG; Hui Miao ZHANG; Bing Nan GUO

    2006-01-01

    A series of piperazine-based Gemini and Bola surfactants were synthesized. Gemini 1and 5 have well surface activities. Their critical micelle concentrations (cmc) is 6.47×10-4 mol/L and 1.17×10-3 mol/L, respectively. Bola surfactants 2 and compound 3, possessing better water solubility, have lower surface activities. Calculation, carried out by MM2 energy minimization,showed that compound with more hydrophobic chains in a spacer of limited length is difficult to be synthesized.

  2. 更胜一筹:Sony DSC-H20

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Sony DSC-H20是H10的后续版本,相比之下新款相机的像素值提高至1010万像素,具备720P、1280×720、30fps高画质录像能力.搭载3英寸、23万像素LCD屏幕。DSC-H20支持双重防抖功能,相机采用10倍光学变焦镜头.

  3. One-step Real-time Food Quality Analysis by Simultaneous DSC-FTIR Microspectroscopy.

    Science.gov (United States)

    Lin, Shan-Yang; Lin, Chih-Cheng

    2016-01-01

    This review discusses an analytical technique that combines differential scanning calorimetry and Fourier-transform infrared (DSC-FTIR) microspectroscopy, which simulates the accelerated stability test and detects decomposition products simultaneously in real time. We show that the DSC-FTIR technique is a fast, simple and powerful analytical tool with applications in food sciences. This technique has been applied successfully to the simultaneous investigation of: encapsulated squid oil stability; the dehydration and intramolecular condensation of sweetener (aspartame); the dehydration, rehydration and solidification of trehalose; and online monitoring of the Maillard reaction for glucose (Glc)/asparagine (Asn) in the solid state. This technique delivers rapid and appropriate interpretations with food science applications.

  4. Surfactant-enhanced desorption and biodegradation of polycyclic aromatic hydrocarbons in contaminated soil.

    Science.gov (United States)

    Zhu, Hongbo; Aitken, Michael D

    2010-10-01

    We evaluated two nonionic surfactants, one hydrophobic (Brij 30) and one hydrophilic (C(12)E(8)), for their ability to enhance the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil after it had been treated in an aerobic bioreactor. The effects of each surfactant were evaluated at doses corresponding to equilibrium aqueous-phase concentrations well above the surfactant's critical micelle concentration (CMC), slightly above the CMC, and below the CMC. The concentrations of all 3- and 4-ring PAHs were significantly lower in the soil amended with Brij 30 at the two lower doses compared to controls, whereas removal of only the 3-ring PAHs was significantly enhanced at the highest Brij 30 dose. In contrast, C(12)E(8) did not enhance PAH removal at any dose. In the absence of surfactant, PAH desorbed from the soil over an 18 day period. Brij 30 addition at the lowest dose significantly increased the desorption of most PAHs, whereas the addition of C(12)E(8) at the lowest dose actually decreased the desorption of all PAHs. These findings suggest that the effects of the two surfactants on PAH biodegradation could be explained by their effects on PAH bioavailability. Overall, this study demonstrates that the properties of the surfactant and its dose relative to the corresponding aqueous-phase concentration are important factors in designing systems for surfactant-enhanced bioremediation of PAH-contaminated soils in which PAH bioavailability is limited.

  5. Effect of nonionic surfactant on wetting behavior of an evaporating drop under a reduced pressure environment.

    Science.gov (United States)

    Sefiane, Khellil

    2004-04-15

    The evaporation of sessile drops at reduced pressure is investigated. The evaporation of water droplets on aluminum and PTFE surfaces at reduced pressure was compared. It was found that water droplets on an aluminum surface exhibit a 'depinning jump' at subatmospheric pressures. This is when a pinned droplet suddenly depins, with an increase in contact angle and a simultaneous decrease in the base width. The evaporation of sessile water droplets with a nonionic surfactant (Triton X-100) added to an aluminum surface was then studied. The initial contact angle exhibited a minimum at 0.001 wt% Triton X-100. A maximum in the evaporation rate was also observed at the same concentration. Droplets with low surfactant concentrations are found to exhibit the 'depinning jump.' It is thought that the local concentration of the surfactant causes a gradient of surface tension. The balance at the contact angle is dictated by complex phenomena, including surfactant diffusion and adsorption processes at interfaces. Due to the strong evaporation near the triple line, an accumulation of the surfactant will lead to a surface tension gradient along the interface. The gradient of surface tension will influence the wetting behavior (Marangoni effect). At low surfactant concentrations the contact line depins under the strong effect of surface tension gradient that develops spontaneously over the droplet interface due to surfactant accumulation near the triple line. The maximum evaporation rate corresponds to a minimum contact angle for a pinned droplet.

  6. Study for optical manipulation of a surfactant-covered droplet using lattice Boltzmann method.

    Science.gov (United States)

    Choi, Se Bin; Kondaraju, Sasidhar; Sang Lee, Joon

    2014-03-01

    In this study, we simulated deformation and surfactant distribution on the interface of a surfactant-covered droplet using optical tweezers as an external source. Two optical forces attracted a single droplet from the center to both sides. This resulted in an elliptical shape deformation. The droplet deformation was characterized as the change of the magnitudes of surface tension and optical force. In this process, a non-linear relationship among deformation, surface tension, and optical forces was observed. The change in the local surfactant concentration resulting from the application of optical forces was also analyzed and compared with the concentration of surfactants subjected to an extensional flow. Under the optical force influence, the surfactant molecules were concentrated at the droplet equator, which is totally opposite to the surfactants behavior under extensional flow, where the molecules were concentrated at the poles. Lastly, the quasi-equilibrium surfactant distribution was obtained by combining the effects of the optical forces with the extensional flow. All simulations were executed by the lattice Boltzmann method which is a powerful tool for solving micro-scale problems.

  7. Surfactant for pediatric acute lung injury.

    Science.gov (United States)

    Willson, Douglas F; Chess, Patricia R; Notter, Robert H

    2008-06-01

    This article reviews exogenous surfactant therapy and its use in mitigating acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) in infants, children, and adults. Biophysical and animal research documenting surfactant dysfunction in ALI/ARDS is described, and the scientific rationale for treatment with exogenous surfactant is discussed. Major emphasis is placed on reviewing clinical studies of surfactant therapy in pediatric and adult patients who have ALI/ARDS. Particular advantages from surfactant therapy in direct pulmonary forms of these syndromes are described. Also discussed are additional factors affecting the efficacy of exogenous surfactants in ALI/ARDS.

  8. Preparation and evaluation of some amide ether carboxylate surfactants

    Directory of Open Access Journals (Sweden)

    M.M.A. El-Sukkary

    2012-06-01

    Full Text Available A homologous series of new mild surfactants, namely: Alkyl amide ether carboxylates surfactants (AEC RCO–NHCH2CH2O (CH2CH2O6CH2COONa, were synthesized by esterification, amidation, ethoxylation and carboxymethylation reaction steps of fatty acids (Lauric, Myristic, palmitic, stearic, oleic or linoleic. The chemical structures of the prepared compounds were confirmed using different spectroscopic techniques, FTIR spectroscopy, mass spectra and HNMR. The surface properties including surface and interfacial tensions, foaming height, emulsification power, calcium ion stability, stability to hydrolysis and critical micelle concentration (cmc were determined. The study of their surface properties showed their stability in hard water and in acidic and alkaline media. These compounds have high calcium ion stability. The low foaming power could have an application in the dyeing auxiliary industry. The lower values of the interfacial tension values indicate the ability of using these surfactants in several applications as corrosion inhibitors and biocides. The data revealed various advantages and potentials as a main surfactant as well as co- surfactants.

  9. Controlling block copolymer phase behavior using ionic surfactant

    Science.gov (United States)

    Ray, D.; Aswal, V. K.

    2016-05-01

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

  10. Anomalous diffusion and stress relaxation in surfactant micelles

    Science.gov (United States)

    Dhakal, Subas; Sureshkumar, Radhakrishna

    2017-07-01

    We investigate the mechanisms of anomalous diffusion in cationic surfactant micelles using molecular dynamics simulations in the presence of explicit salt and solvent-mediated interactions. Simulations show that when the counterion density increases, saddle-shaped branched interfaces manifest. In experiments, branched structures exhibit lower viscosity as compared to linear and wormlike micelles. This has long been attributed to stress relaxation arising from the sliding motion of branches along the main chain. Our simulations reveal a mechanism of branch motion resulting from an enhanced counterion condensation at the branched interfaces and provide quantitative evidence of stress relaxation facilitated by branched sliding. Furthermore, depending on the surfactant and salt concentrations, which in turn determine the microstructure, we observe normal, subdiffusive, and superdiffusive motions of surfactants. Specifically, superdiffusive behavior is associated with branch sliding, breakage and recombination of micelle fragments, as well as constraint release in entangled systems.

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

    Directory of Open Access Journals (Sweden)

    Naved Azum

    2016-11-01

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

  12. Determination of alkylbenzenesulfonate surfactants in groundwater using macroreticular resins and carbon-13 nuclear magnetic resonance spectrometry

    Science.gov (United States)

    Thurman, E.M.; Willoughby, T.; Barber, L.B.; Thorn, K.A.

    1987-01-01

    Alkylbenzenesulfonate surfactants were determined in groundwater at concentrations as low as 0.3 mg/L. The method uses XAD-8 resin for concentration, followed by elution with methanol, separation of anionic and nonionic surfactants by anion exchange, quantitation by titration, and identification by 13C nuclear magnetic resonance spectrometry. Laboratory standards and field samples containing straight-chain and branched-chain alkylbenzenesulfonates, sodium dodecyl sulfate, and alkylbenzene ethoxylates were studied. The XAD-8 extraction of surfactants from groundwater was completed in the field, which simplified sample preservation and reduced the cost of transporting samples.

  13. Small angle neutron scattering studies on the interaction of cationic surfactants with bovine serum albumin

    Indian Academy of Sciences (India)

    Nuzhat Gull; S Chodankar; V K Aswal; Kabir-Ud-Din

    2008-11-01

    The structure of the protein–surfactant complex of bovine serum albumin (BSA) and cationic surfactants has been studied by small angle neutron scattering. At low concentrations, the CTAB monomers are observed to bind to the protein leading to an increase in its size. On the other hand at high concentrations, surfactant molecules aggregate along the unfolded polypeptide chain of the protein resulting in the formation of a fractal structure representing a necklace model of micelle-like clusters randomly distributed along the polypeptide chain. The fractal dimension as well as the size and number of micelles attached to the complex have been determined.

  14. Influence of nonionic surfactant on the solubilization and biodegradation of phenanthrene

    Institute of Scientific and Technical Information of China (English)

    YANG Jian-gang; LIU Xiang; LONG Tao; YU Gang; PENG She; ZHENG Liu

    2003-01-01

    Phenanthrene was solubilized in two different nonionic surfactants, Tween80 and Triton X-100. The bioavailability of phenanthrene to the bacteria isolated from the petroleum contaminated soils was studied based on the rotary flasks experiments. The results showed that the concentration of nonionic surfactants above the critical micelle concentration(CMC) can increase the solubility of phenanthrene in water and were innoxious to the phenanthrene-degrading bacteria; phenanthrene solubilized in the micelles of Tween80 was bioavailable and biodegradable. The research demonstrated the potential of surfactant-enhanced bioremediation of soils contaminated by hydrophobic organic compounds( HOCs).

  15. Nanofiltration: ion exchange system for effective surfactant removal from water solutions

    Directory of Open Access Journals (Sweden)

    I. Kowalska

    2014-12-01

    Full Text Available A system combining nanofiltration and ion exchange for highly effective separation of anionic surfactant from water solutions was proposed. The subjects of the study were nanofiltration polyethersulfone membranes and ion-exchange resins differing in type and structure. The quality of the treated solution was affected by numerous parameters, such as quality of the feed solution, membrane cut-off, resin type, dose and the solution contact time with the resin. A properly designed purification system made it possible to reduce the concentration of anionic surfactant below 1 mg L-1 from feed solutions containing surfactant in concentrations above the CMC value.

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

    Science.gov (United States)

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

    2015-05-15

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

  17. Surfactant and nonlinear drop dynamics in microgravity

    Science.gov (United States)

    Jankovsky, Joseph Charles

    2000-11-01

    Large amplitude drop dynamics in microgravity were conducted during the second United States Microgravity Laboratory mission carried onboard the Space Shuttle Columbia (20 October-5 November 1995). Centimeter- sized drops were statically deformed by acoustic radiation pressure and released to oscillate freely about a spherical equilibrium. Initial aspect ratios of up to 2.0 were achieved. Experiments using pure water and varying aqueous concentrations of Triton-X 100 and bovine serum albumin (BSA) were performed. The axisymmetric drop shape oscillations were fit using the degenerate spherical shape modes. The frequency and decay values of the fundamental quadrupole and fourth order shape mode were analyzed. Several large amplitude nonlinear oscillation dynamics were observed. Shape entrainment of the higher modes by the fundamental quadrupole mode occurred. Amplitude- dependent effects were observed. The nonlinear frequency shift, where the oscillation frequency is found to decrease with larger amplitudes, was largely unaffected by the presence of surfactants. The percentage of time spent in the prolate shape over one oscillation cycle was found to increase with oscillation amplitude. This prolate shape bias was also unaffected by the addition of surfactants. These amplitude-dependent effects indicate that the nonlinearities are a function of the bulk properties and not the surface properties. BSA was found to greatly enhance the surface viscoelastic properties by increasing the total damping of the oscillation, while Triton had only a small influence on damping. The surface concentration of BSA was found to be diffusion-controlled over the time of the experiments, while the Triton diffusion rate was very rapid. Using the experimental frequency and decay values, the suface viscoelastic properties of surface dilatational viscosity ( ks ) and surface shear viscosity ( ms ) were found for varying surfactant concentrations using the transcendental equation of Lu

  18. Model study of enhanced oil recovery by flooding with aqueous surfactant solution and comparison with theory.

    Science.gov (United States)

    Fletcher, Paul D I; Savory, Luke D; Woods, Freya; Clarke, Andrew; Howe, Andrew M

    2015-03-17

    With the aim of elucidating the details of enhanced oil recovery by surfactant solution flooding, we have determined the detailed behavior of model systems consisting of a packed column of calcium carbonate particles as the porous rock, n-decane as the trapped oil, and aqueous solutions of the anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT). The AOT concentration was varied from zero to above the critical aggregation concentration (cac). The salt content of the aqueous solutions was varied to give systems of widely different, post-cac oil-water interfacial tensions. The systems were characterized in detail by measuring the permeability behavior of the packed columns, the adsorption isotherms of AOT from the water to the oil-water interface and to the water-calcium carbonate interface, and oil-water-calcium carbonate contact angles. Measurements of the percent oil recovery by pumping surfactant solutions into calcium carbonate-packed columns initially filled with oil were analyzed in terms of the characterization results. We show that the measured contact angles as a function of AOT concentration are in reasonable agreement with those calculated from values of the surface energy of the calcium carbonate-air surface plus the measured adsorption isotherms. Surfactant adsorption onto the calcium carbonate-water interface causes depletion of its aqueous-phase concentration, and we derive equations which enable the concentration of nonadsorbed surfactant within the packed column to be estimated from measured parameters. The percent oil recovery as a function of the surfactant concentration is determined solely by the oil-water-calcium carbonate contact angle for nonadsorbed surfactant concentrations less than the cac. For surfactant concentrations greater than the cac, additional oil removal occurs by a combination of solubilization and emulsification plus oil mobilization due to the low oil-water interfacial tension and a pumping pressure increase.

  19. Viscoelasticity Enhancement of Surfactant Solutions Depends on Molecular Conformation: Influence of Surfactant Headgroup Structure and Its Counterion.

    Science.gov (United States)

    Lutz-Bueno, Viviane; Pasquino, Rossana; Liebi, Marianne; Kohlbrecher, Joachim; Fischer, Peter

    2016-05-03

    During the anisotropic growth from globular to wormlike micelles, the basic interactions among distinct parts of the surfactant monomer, its counterion, and additives are fundamental to tune molecular self-assembly. We investigate the addition of sodium salicylate (NaSal) to hexadecyltrimethylammonium chloride and bromide (CTAC and CTAB), 1-hexadecylpyridinium chloride and bromide (CPyCl and CPyBr), and benzyldimethylhexadecylammonium chloride (BDMC), which have the same hydrophobic tail. Their potential to enhance viscoelasticity by anisotropic micellar growth upon salt addition was compared in terms of (i) the influence of the headgroup structure, and (ii) the influence of surfactant counterion type. Employing proton nuclear magnetic resonance ((1)H NMR), we focused on the molecular conformation of surfactant monomers in the core and polar shell regions of the micelles and their interactions with increasing concentration of NaSal. The viscoelastic response was investigated by rotational and oscillatory rheology. We show that micellar growth rates can be tuned by varying the flexibility and size of the surfactant headgroup as well as the dissociation degree of the surfactant counterion, which directly influences the strength of headgroup-counterion pairing. As a consequence, the morphological transitions depend directly on charge neutralization by electrostatic screening. For example, the amount of salt necessary to start the rodlike-to-wormlike micelle growth depends directly on the number of dissociated counterions in the polar shell.

  20. Spontaneous surface self-assembly in protein-surfactant mixtures: interactions between hydrophobin and ethoxylated polysorbate surfactants.

    Science.gov (United States)

    Tucker, Ian M; Petkov, Jordan T; Penfold, Jeffrey; Thomas, Robert K; Li, Peixun; Cox, Andrew R; Hedges, Nick; Webster, John R P

    2014-05-01

    The synergistic interactions between certain ethoxylated polysorbate nonionic surfactants and the protein hydrophobin result in spontaneous self-assembly at the air-water interface to form layered surface structures. The surface structures are characterized using neutron reflectivity. The formation of the layered surface structures is promoted by the hydrophobic interaction between the polysorbate alkyl chain and the hydrophobic patch on the surface of the globular hydrophobin and the interaction between the ethoxylated sorbitan headgroup and hydrophilic regions of the protein. The range of the ethoxylated polysorbate concentrations over which the surface ordering occurs is a maximum for the more hydrophobic surfactant polyoxyethylene(8) sorbitan monostearate. The structures at the air-water interface are accompanied by a profound change in the wetting properties of the solution on hydrophobic substrates. In the absence of the polysorbate surfactant, hydrophobin wets a hydrophobic surface, whereas the hydrophobin/ethoxylated polysorbate mixtures where multilayer formation occurs result in a significant dewetting of hydrophobic surfaces. The spontaneous surface self-assembly for hydrophobin/ethoxylated polysorbate surfactant mixtures and the changes in surface wetting properties provide a different insight into protein-surfactant interactions and potential for manipulating surface and interfacial properties and protein surface behavior.

  1. Photocatalytic Degradation of Diethyl Phthalate with Surfactant Addition

    Institute of Scientific and Technical Information of China (English)

    ZHANG Tianyong; HU Juan; ZHANG Youlan; LI Bin; FEI Xuening

    2006-01-01

    This paper studies the adsorption of diethyl phthalate (DEP,an environmental hormone) on the surface of nanoscale TiO2, effects of pH value of solutions, initial concentrations of DEP and additive surfactant on photocatalytic degradation and dynamics of DEP. Under ultra violet illumination, the interaction between DEP and surfactants including DBS (sodium dodecylbenzenesulfonate), CTAB (cetyltrimethylammonium bromide), and OP-10 (nonylphenol polyoxyethylene ether)was exploited from the perspective of degradation speed calculated by the data of high pressure liquid chromatography (HPLC) and UV-Vis spectra, respectively. Photocatalytic degradation of DEP followed pseudo first-order reaction kinetics. DEP as substrate degraded fast when its initial concentration was 130 mg/L. TiO2 had certain adsorption ability of DEP. TiO2 could adsorb the most DEP at the approximately neutral pH of 6.91. Degradation of DEP was not affected obviously by ad ditives OP-10 and JBS. Degradation rate of DEP was not enhanced greatly in the presence of surfactants, but degradation of DBS was sped up. Degradation rate of DEP was depressed in the presence of additive CTAB. The more CTAB was added, the less DEP was degraded. Degradation rate of CTAB became slow with the increase of initial CTAB concentration. The possible adsorption models among TiO2, DEP and surfactants were given.

  2. Evaluation and application of surfactants synthesized from asphalt components

    Directory of Open Access Journals (Sweden)

    E.R. Souaya

    2012-06-01

    Full Text Available The synthesis, characterization, surface activity and applications of nonionic surfactants derived from the asphalt components (maltenes M are presented. These compounds were synthesized by the sulfonation of (maltene, then the prepared maltene sulfonic acid (MS was reacted with hexadecylamine giving maltene sulfonamide product (A which undergoes an alkali-catalyzed ethoxylation at (135–150 °C. Several surfactants (M-10 to M-40 were formed with different ethylene oxide units (from 10 up to 40 and were characterized by molecular weight determinations, elemental analyses and FTIR analysis. Surface tension, as a function of concentration of the surfactants in the aqueous media, was measured at 25 °C. From these measurements, the critical micelle concentration (CMC, the maximum surface excess concentration (Гmax, Minimum area per molecule (Amin, effectiveness of surface reduction (ПCMC and the efficiency (pC20 were calculated. The prepared surfactants were applied as emulsifying agents for making asphalt emulsions. Storage stability, (Saybolt Furol viscosity, settlement (water content difference %, coating ability and water resistance were measured. The results indicated that M-20 (maltene sulfonamide ethoxylated with 20 units of ethylene oxides gives a maximum stability.

  3. Alkali/Surfactant/Polymer Flooding in the Daqing Oilfield Class II Reservoirs Using Associating Polymer

    Directory of Open Access Journals (Sweden)

    Ru-Sen Feng

    2013-01-01

    Full Text Available Hydrophobically modified associating polyacrylamide (HAPAM has good compatibility with the Daqing heavy alkylbenzene sulfonate surfactant. The HAPAM alkali/surfactant/polymer (ASP system can generate ultralow interfacial tension in a wide range of alkali/surfactant concentrations and maintain stable viscosity and interfacial tension for 120 days. The HAPAM ASP system has good injectivity for the Daqing class II reservoirs (100–300 × 10−3 μm2 and can improve oil recovery by more than 25% on top of water flooding. In the presence of both the alkali and the surfactant, the surfactant interacts with the associating groups of the polymer to form more micelles, which can significantly enhance the viscosity of the ASP system. Compared with using HPAM (Mw = 2.5 MDa, using HAPAM can reduce the polymer use by more than 40%.

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

    Directory of Open Access Journals (Sweden)

    Naeem Kashif

    2012-01-01

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

  5. Characterisation of gas hydrates formation and dissociation using high pressure DSC

    Energy Technology Data Exchange (ETDEWEB)

    Le Parlouer, P. [Thermal Consulting, Caluire (France); Etherington, G. [Setaram Inc., Pennsauken, NJ (United States)

    2008-07-01

    This paper provided details of an innovative methodology that used a high pressure micro-scale differential scanning calorimetry (DSC) method to characterize the thermodynamic properties and kinetics of gas hydrate formation. The calorimeter was based on a symmetrical heat flux design that used a Peltier cooling and heating principle. No refrigerating fluids were required. The method described phase transitions in relation to time, temperature and pressure. The DSC method was designed for use with gas hydrates trapped in marine sediments; hydrate formation in drilling muds and annulars during offshore oil and gas extraction; the storage and transportation of natural gas; and gas hydrate formation and dissociation for cold storage and transportation. Tests demonstrated that the DSC accurately predicted the formation of gas hydrates under high pressure conditions. Experimental studies were conducted to investigate salt solutions under methane pressure; and hydrate dissociation in a sodium chloride (NaC1) and ethyleneglycol solution. Data obtained comparing the method with classical PVT techniques showed that the MicroDSC technique was less time-consuming and required smaller sample volumes. It was concluded that the method is suitable for use with various types of fluids. 13 refs., 7 figs.

  6. Recent advances and potential applications of modulated differential scanning calorimetry (mDSC) in drug development

    DEFF Research Database (Denmark)

    Knopp, Matthias Manne; Löbmann, Korbinian; Elder, David P.

    2016-01-01

    of these applications. It is aimed to serve as a broad introduction to newcomers, and also as a valuable reference for those already practising in the field. Complex mDSC was introduced more than two decades ago and has been an important tool for the quantification of amorphous materials and development of freeze...

  7. DSC and NMR Study on the Inclusion Complex of Lappaconitine with β—Cyclodextrin

    Institute of Scientific and Technical Information of China (English)

    KaiJunLIAO; XiaoHuaYAN; 等

    2002-01-01

    The inclusion complex of lappaconitine(Lap) with β-cyclodextrin (β-CD) has been studied by the differential scanning calorimetry (DSC) and 1H-NMR,2D-NMR spectroscopy. The structure of the complex has been deduced.

  8. DSC and NMR Study on the Inclusion Complex of Lappaconitine with β-Cyclodextrin

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The inclusion complex of lappaconitine (Lap) with β-cyclodextrin (β-CD) has been studied by the differential scanning calorimetry (DSC) and 1H-NMR, 2D-NMR spectroscopy.The structure of the complex has been deduced.``

  9. Multispectral image compression based on DSC combined with CCSDS-IDC.

    Science.gov (United States)

    Li, Jin; Xing, Fei; Sun, Ting; You, Zheng

    2014-01-01

    Remote sensing multispectral image compression encoder requires low complexity, high robust, and high performance because it usually works on the satellite where the resources, such as power, memory, and processing capacity, are limited. For multispectral images, the compression algorithms based on 3D transform (like 3D DWT, 3D DCT) are too complex to be implemented in space mission. In this paper, we proposed a compression algorithm based on distributed source coding (DSC) combined with image data compression (IDC) approach recommended by CCSDS for multispectral images, which has low complexity, high robust, and high performance. First, each band is sparsely represented by DWT to obtain wavelet coefficients. Then, the wavelet coefficients are encoded by bit plane encoder (BPE). Finally, the BPE is merged to the DSC strategy of Slepian-Wolf (SW) based on QC-LDPC by deep coupling way to remove the residual redundancy between the adjacent bands. A series of multispectral images is used to test our algorithm. Experimental results show that the proposed DSC combined with the CCSDS-IDC (DSC-CCSDS)-based algorithm has better compression performance than the traditional compression approaches.

  10. Brain Metastases from Different Primary Carcinomas: an Evaluation of DSC MRI Measurements.

    Science.gov (United States)

    Zhang, H; Zhang, G; Oudkerk, M

    2012-03-01

    This study evaluated the roles of different dynamic susceptibility contrast magnetic imaging (DSC MRI) measurements in discriminating between brain metastases derived from four common primary carcinomas. Thirty-seven patients with brain metastases were enrolled. Relative cerebral blood volume (rCBV), cerebral blood flow (rCBF) and relative mean transit time (rMTT) in both tumor and peritumoral edema were measured. Metastases were grouped by their primary tumor (lung, gastrointestinal, breast and renal cell carcinoma). DSC MRI measurements were compared between groups. Mean rCBV, rCBF, rMTT in tumor and peritumoral edema of all brain metastases (n=37) were 2.79 ± 1.73, 2.56 ± 2.11, 1.21 ± 0.48 and 1.05 ± 0.53, 0.86 ± 0.40, 1.99 ± 0.41, respectively. The tumoral rCBV (5.26 ± 1.89) and rCBF (5.32 ± 3.28) of renal metastases were greater than those of the other three metastases (P0.05). Evaluating various DSC MRI measurements can provide complementary hemodynamic information on brain metastases. The tumoral rCBV, rCBF and likely rMTT can help discriminate between brain metastases originating from different primary carcinomas. The peritumoral DSC MRI measurements had limited value in discriminating between brain metastases.

  11. Rheological and DSC Studies on the Interaction between κ-Carrageenan and Cellulose Nanocrystals (CNC)

    Institute of Scientific and Technical Information of China (English)

    Rui GUO; En Yong DING

    2006-01-01

    Rheometer and differential scanning calorimetry (DSC) have been used to probe the mechanism of gelation in gels formed by mixture of κ-carrageenan and cellulose nanocrystals (CNC). The results indicated that an association occurred between CNC chains and aggregated κ-carrageenan helices.

  12. Thermal analysis on parchments I: DSC and TGA combined approach for heat damage assessment

    DEFF Research Database (Denmark)

    Fessas, D.; Signorelli, M.; Schiraldi, A.;

    2006-01-01

    Ancient, new and artificially aged parchments were investigated with both differential scanning calorimetry (DSC) and thermogravimetry (TGA). Criteria to define a quantitative ranking of the damage experienced by the bulk collagen of historical parchments were assessed. A damage-related correlati...

  13. Determining the main thermodynamic parameters of caffeine melting by means of DSC

    Science.gov (United States)

    Agafonova, E. V.; Moshchenskii, Yu. V.; Tkachenko, M. L.

    2012-06-01

    The temperature and enthalpy of the melting of caffeine, which are 235.5 ± 0.1°C and 19.6 ± 0.2 kJ/mol, respectively, are determined by DSC. The melting entropy and the cryoscopic constant of caffeine are calculated.

  14. Thermal analysis on parchments I: DSC and TGA combined approach for heat damage assessment

    DEFF Research Database (Denmark)

    Fessas, D.; Signorelli, M.; Schiraldi, A.

    2006-01-01

    Ancient, new and artificially aged parchments were investigated with both differential scanning calorimetry (DSC) and thermogravimetry (TGA). Criteria to define a quantitative ranking of the damage experienced by the bulk collagen of historical parchments were assessed. A damage-related correlati...

  15. Rapid examination of the kinetic process of intramolecular lactamization of gabapentin using DSC-FTIR

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, C.-H. [Lab. Pharm. Biopharm., Department of Biotechnology, Yuanpei University, Hsin Chu, Taiwan (China); Lin, S.-Y. [Lab. Pharm. Biopharm., Department of Biotechnology, Yuanpei University, Hsin Chu, Taiwan (China)], E-mail: sylin@mail.ypu.edu.tw

    2009-03-20

    The thermal stability and thermodynamics of gabapentin (GBP) in the solid state were investigated by DSC and TG techniques, and FTIR microspectroscopy. The detailed intramolecular lactamization process of GBP to form gabapentin-lactam (GBP-L) was also determined by thermal FTIR microspectroscopy. GBP exhibited a DSC endothermic peak at 169 deg. C. The weight loss in TG curve of GBP suggested that the evaporation process of water liberated via intramolecular lactamization was simultaneously combined with the evaporation process of GBP-L having a DSC endothermic peak at 91 deg. C. A thermal FTIR microspectroscopy clearly evidenced the IR spectra at 3350 cm{sup -1} for water liberated and at 1701 cm{sup -1} for lactam structure formed due to the lactam formation of GBP. This study indicates that the activation energy for combined processes of intramolecular lactamization of GBP and evaporation of GBP-L was about 114.3 {+-} 23.3 kJ/mol, but for the evaporation of GBP-L alone was 76.2 {+-} 1.5 kJ/mol. A powerful simultaneous DSC-FTIR combined technique was easily used to quickly examine the detailed kinetic processes of intramolecular cyclization of GPB and evaporation of GBP-L in the solid state.

  16. DSC of human hair: a tool for claim support or incorrect data analysis?

    Science.gov (United States)

    Popescu, C; Gummer, C

    2016-10-01

    Differential scanning calorimetry (DSC) data are increasingly used to substantiate product claims of hair repair. Decreasing peak temperatures may indicate structural changes and chemical damage. Increasing the DSC, wet peak temperature is, therefore, often considered as proof of hair repair. A detailed understanding of the technique and hair structure indicates that this may not be a sound approach. Surveying the rich literature on the use of dynamic thermal analysis (DTA) and differential scanning calorimetry (DSC) for the analyses of human hair and the effect of cosmetic treatments, we underline some of the problems of hair structure and data interpretation. To overcome some of the difficulties of data interpretation, we advise that DSC acquired data should be supported by other techniques when used for claim substantiation. In this way, one can provide meaningful interpretation of the hair science and robust data for product claims support. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  17. 触,爱 SONY DSC-T2索尼数码相机

    Institute of Scientific and Technical Information of China (English)

    邢瑜

    2007-01-01

    索尼DSC-T2数码相机是DSC-T1的升级产品.与DSC-T1相比.要小巧秀气了许多.在没有打开镜头的时候,很多人都会误以为它是一个播放器或是小首饰盒之类的物件,无意中DSC-T2迷惑了众人的眼睛。

  18. Evaluation of therapeutic pulmonary surfactants by thin liquid film methods.

    Science.gov (United States)

    Todorov, Roumen; Exerowa, Dotchi; Platikanov, Dimo; Bianco, Federico; Razzetti, Roberta

    2015-08-01

    An example of the application of the Black Foam Film (BFF) Method and the Wetting Film Method, using the Microinterferomertric and the Pressure Balance Techniques, for characterization interfacial properties of the animal derived therapeutic pulmonary surfactant preparations (TSP), is presented. BFF thickness, probability of black film formation, and disjoining pressure for foam films from TSP aqueous solutions are measured as well as the wetting properties of TSP solutions on solid surfaces with different hydrophobicity have been studied. Interfacial characteristics such as minimal surfactant concentration to obtain black film (critical concentration) and concentration at which a black film is 100% obtained (threshold concentration) are determined. An evaluation of the four widely used TSP – Curosurf, Infasurf, Survanta, and Alveofact – by these methods has been carried out. Thus the methods of the thin liquid films are useful tools for studying the interfacial properties of TSP solutions, as well as for their improvement.

  19. Anomalous thickness variation of the foam films stabilized by weak non-ionic surfactants.

    Science.gov (United States)

    Qu, Xuan; Wang, Liguang; Karakashev, Stoyan I; Nguyen, Anh V

    2009-09-15

    The constant thickness (H) of metastable free films of various non-ionic surfactant solutions was measured at surfactant concentrations less than the critical micelle concentrations or solubility limits with fixed 5x10(-5) M sodium chloride (NaCl) serving as the background electrolyte. The surfactants include n-pentanol, n-octanol, methyl isobutyl carbinol (MIBC), polypropylene glycol (PPG-400), tetraethylene glycol monooctyl ether (C(8)E(4)), and tetraethylene glycol monodecyl ether (C(10)E(4)). H was interferometrically measured. For each surfactant in this study, the H-versus-surfactant-concentration curve finds a peak at a concentration around 5x10(-6)-1x10(-5) M and a valley at a higher concentration. The measured H values were compared to those predicted from the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, which considers solely the contribution from electrostatic double-layer repulsion with van der Waals attraction being neglected in the present work. In determining the double-layer repulsion, the ionic strength was determined from the electrolytic conductivity measurement of the film-forming solutions and the surface potential was estimated from the zeta-potential measurement of air bubbles. It was found that the DLVO theory failed to explain the thickness variance with surfactant concentration, implying that additional non-DLVO attractive forces might be required to explain the experimental results. Finally, the possible origins of these attractive forces were discussed.

  20. 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.

  1. Rheological characterization of polysaccharide-surfactant matrices for cosmetic O/W emulsions.

    Science.gov (United States)

    Bais, D; Trevisan, A; Lapasin, R; Partal, P; Gallegos, C

    2005-10-15

    Rheometrical techniques can be profitably used for polysaccharide matrices in order to evaluate their suitability for the preparation of stable cosmetic O/W emulsions. In particular, the rheological properties of aqueous scleroglucan systems were investigated under continuous and oscillatory shear conditions in a polymer concentration range (0.2-1.2% w/w) embracing the sol/gel transition. The effects due to the addition of two different surfactants (up to 10% w/w) were examined at constant polymer concentration (0.4% w/w). The selected additives are a nonionic polymeric siliconic surfactant (dimethicone copolyol) and a cationic surfactant (tetradecyltrimethylammonium bromide), respectively. Polysaccharide-surfactant interactions leading to complex formation were detected also through rheology. The combined action of both nonionic and cationic surfactants in the polymer solution was examined at two different surfactant concentration levels (5 and 10% w/w), demonstrating the beneficial effects produced on the mechanical properties of the polymer matrix by the coexistence of both surfactants. Such beneficial effects are confirmed by the stability and rheology shown by the emulsions prepared. In this way, the results point out the good agreement between the rheology of the continuous phase and the final characteristics of the emulsion obtained.

  2. Diester-containing Zwitterionic Gemini Surfactants with Different Spacer and Its Impact on Micellization Properties and Viscosity of Aqueous Micellar Solution.

    Science.gov (United States)

    Patil, Sachin Vasant; Patil, Sanyukta Arun; Pratap, Amit Prabhakar

    2016-09-01

    A series of diester containing zwitterionic gemini surfactants, N,N-dimethyl-N-alkyl-2-[[hydroxy (alkoxy) phosphinyl]oxy]-alkylammonium designated as C8(-)-S-Cn(+), S = 2 and 3, n = 12, 14 and 16, were synthesized and characterized by instrumental techniques namely FT-IR, (1)H NMR, (13)C NMR, (31)P NMR and Mass spectral studies. These new gemini surfactants further investigated for their various surfactant properties. The critical micelle concentration (cmc) and the effectiveness of surface tension reduction (Πcmc) were determined as a function of surfactant concentration by means of surface tension measurement. Micellization and viscosity properties were investigated by surface tension, electrical conductivity, dye micellization and rheology techniques. The findings of the aqueous surfactant system obtained were impacted by polarity, size and the nature of zwitterions as the surface. The thermodynamic and viscosity properties of these surfactants found to be based on the structures of gemini surfactants.

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

    Directory of Open Access Journals (Sweden)

    Braun Armin

    2009-09-01

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

  4. Utilizing surfactants to control the sorption, desorption, and biodegradation of phenanthrene in soil-water system.

    Science.gov (United States)

    Jin, Haiwei; Zhou, Wenjun; Zhu, Lizhong

    2013-07-01

    An integrative technology including the surfactant enhanced sorption and subsequent desorption and biodegradation of phenanthrene in the soil-water system was introduced and tested. For slightly contaminated agricultural soils, cationic-nonionic mixed surfactant-enhanced sorption of organic contaminants onto soils could reduce their transfer to plants, therefore safe-guarding agricultural production. After planting, residual surfactants combined with added nonionic surfactant could also promote the desorption and biodegradation of residual phenanthrene, thus providing a cost-effective pollution remediation technology. Our results showed that the cationic-nonionic mixed surfactants dodecylpyridinium bromide (DDPB) and Triton X-100 (TX100) significantly enhanced soil retention of phenanthrene. The maximum sorption coefficient Kd of phenanthrene for contaminated soils treated by mixed surfactants was about 24.5 times that of soils without surfactant (Kd) and higher than the combined effects of DDPB and TX100 individually, which was about 16.7 and 1.5 times Kd, respectively. On the other hand, TX100 could effectively remove phenanthrene from contaminated soils treated by mixed surfactants, improving the bioavailability of organic pollutants. The desorption rates of phenanthrene from these treated soils were greater than 85% with TX100 concentration above 2000 mg/L and approached 100% with increasing TX100 concentration. The biodegradation rates of phenanthrene in the presence of surfactants reached over 95% in 30 days. The mixed surfactants promoted the biodegradation of phenanthrene to some extent in 10-22 days, and had no obvious impact on phenanthrene biodegradation at the end of the experiment. Results obtained from this study provide some insight for the production of safe agricultural products and a remediation scheme for soils slightly contaminated with organic pollutants.

  5. Complex Formation Between Polyelectrolytes and Ionic Surfactants

    OpenAIRE

    1998-01-01

    The interaction between polyelectrolyte and ionic surfactant is of great importance in different areas of chemistry and biology. In this paper we present a theory of polyelectrolyte ionic-surfactant solutions. The new theory successfully explains the cooperative transition observed experimentally, in which the condensed counterions are replaced by ionic-surfactants. The transition is found to occur at surfactant densities much lower than those for a similar transition in non-ionic polymer-sur...

  6. Use of amine oxide surfactants for chemical flooding EOR (enhanced oil recovery)

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, D.K.

    1989-11-01

    The use of amine oxides with and without alcohols as cosolvents, and in combination with other surfactants as mixed micellar formulations for enhanced oil recovery by surfactant flooding was investigated. Amine oxides are a salt-tolerant class of surfactants that produce low interfacial tension and can develop viscosity without the addition of polymers. These salt-tolerant formulations generate three-phase regions with hydrocarbons over a broad salinity range, develop moderate solubilization, and produce low interfacial tensions, however oil recovery from amine oxide-alcohol phase behavior optimized formulations was directly dependent upon the quantity of surfactant injected. The large pore volume and high concentration of surfactant required prohibits their economic use as the primary surfactant in chemical flooding EOR. Dimethylalkylamine oxides are useful as cosurfactants and viscosifiers in formulations with other surfactants for chemical flooding EOR but the use of ethoxylated and propoxylated amine oxides should be avoided due to the decomposition of these amine oxides under reservoir conditions. Phase behavior, phase inversion temperatures, and viscosity scans have been correlated with surfactant structures to provide a guide for amine oxide applications in chemical flooding. 36 refs., 5 figs., 6 tabs.

  7. Non-ionic surfactants do not consistently improve the enzymatic hydrolysis of pure cellulose.

    Science.gov (United States)

    Zhou, Yan; Chen, Hongmei; Qi, Feng; Zhao, Xuebing; Liu, Dehua

    2015-04-01

    Non-ionic surfactants have been frequently reported to improve the enzymatic hydrolysis of pretreated lignocellulosic biomass and pure cellulose. However, how the hydrolysis condition, substrate structure and cellulase formulation affect the beneficial action of surfactants has not been well elucidated. In this work, it was found that the enzymatic hydrolysis of pure cellulose was not consistently improved by surfactants. Contrarily, high surfactant concentration, e.g. 5 g/L, which greatly improved the hydrolysis of dilute acid pretreated substrates, actually showed notable inhibition to pure cellulose conversion in the late phase of hydrolysis. Under an optimal hydrolysis condition, the improvement by surfactant was limited, but under harsh conditions surfactant indeed could enhance cellulose conversion. It was proposed that non-ionic surfactants could interact with substrates and cellulases to impact the adsorption behaviors of cellulases. Therefore, the beneficial action of surfactants on pure cellulose hydrolysis is influenced by hydrolysis condition, cellulose structural features and cellulase formulation. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    Jardak, K; Drogui, P; Daghrir, R

    2016-02-01

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

  9. Mobilization of arsenic from contaminated sediment by anionic and nonionic surfactants.

    Science.gov (United States)

    Liang, Chuan; Peng, Xianjia

    2017-06-01

    The increasing manufacture of surfactants and their wide application in industry, agriculture and household detergents have resulted in large amounts of surfactant residuals being discharged into water and distributed into sediment. Surfactants have the potential to enhance arsenic mobility, leading to risks to the environment and even human beings. In this study, batch and column experiments were conducted to investigate arsenic mobilization from contaminated sediment by the commercial anionic surfactants sodium dodecylbenzenesulfonate (SDBS), sodium dodecyl sulfate (SDS), sodium laureth sulfate (AES) and nonionic surfactants phenyl-polyethylene glycol (Triton X-100) and polyethylene glycol sorbitan monooleate (Tween-80). The ability of surfactants to mobilize arsenic followed the order AES>SDBS>SDS≈Triton X-100>Tween 80. Arsenic mobilization by AES and Triton X-100 increased greatly with the increase of surfactant concentration and pH, while arsenic release by SDBS, SDS and Tween-80 slightly increased. The divalent ion Ca(2+) caused greater reduction of arsenic mobilization than Na(+). Sequential extraction experiments showed that the main fraction of arsenic mobilized was the specifically adsorbed fraction. Solid phase extraction showed that arsenate (As(V)) was the main species mobilized by surfactants, accounting for 65.05%-77.68% of the total mobilized arsenic. The mobilization of arsenic was positively correlated with the mobilization of iron species. The main fraction of mobilized arsenic was the dissolved fraction, accounting for 70% of total mobilized arsenic. Copyright © 2016. Published by Elsevier B.V.

  10. Effects of imidazolium-based ionic surfactants on the size and dynamics of phosphatidylcholine bilayers with saturated and unsaturated chains.

    Science.gov (United States)

    Lee, Hwankyu

    2015-07-01

    Imidazolium-based ionic surfactants of different sizes were simulated with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers. Regardless of the phospholipid type, larger surfactants at higher concentrations more significantly insert into the bilayer and increase the bilayer-surface size, in agreement with experiments and previous simulations. Insertion of surfactants only slightly decreases the bilayer thickness, as also observed in experiments. Although the surfactant insertion and its effect on the bilayer size and thickness are similar in different types of bilayers, the volume fractions of surfactants in the bilayer are higher for DMPC bilayers than for POPC and DOPC bilayers. In particular, ionic surfactants with four hydrocarbons yield their volume fractions of 4.6% and 8.7%, respectively, in POPC and DMPC bilayers, in quantitative agreement with experimental values of ∼5% and ∼10%. Also, the inserted surfactants increase the lateral diffusivity of the bilayer, which depends on the bilayer type. These findings indicate that although the surfactant insertion does not depend on the bilayer type, the effects of surfactants on the volume fraction and bilayer dynamics occur more significantly in the DMPC bilayer because of the smaller area per lipid and shorter saturated tails, which helps explain the experimental observations regarding different volume fractions of surfactants in POPC and DMPC bilayers.

  11. 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.

  12. Simulations of impinging droplets with surfactant-dependent dynamic contact angle

    Science.gov (United States)

    Ganesan, Sashikumaar

    2015-11-01

    An arbitrary Lagrangian-Eulerian (ALE) finite element scheme for computations of soluble surfactant droplet impingement on a horizontal surface is presented. The numerical scheme solves the time-dependent Navier-Stokes equations for the fluid flow, scalar convection-diffusion equation for the surfactant transport in the bulk phase, and simultaneously, surface evolution equations for the surfactants on the free surface and on the liquid-solid interface. The effects of surfactants on the flow dynamics are included into the model through the surface tension and surfactant-dependent dynamic contact angle. In particular, the dynamic contact angle (θd) of the droplet is defined as a function of the surfactant concentration at the contact line and the equilibrium contact angle (θe0) of the clean surface using the nonlinear equation of state for surface tension. Further, the surface forces are included into the model as surface divergence of the surface stress tensor that allows to incorporate the Marangoni effects without calculating the surface gradient of the surfactant concentration on the free surface. In addition to a mesh convergence study and validation of the numerical results with experiments, the effects of adsorption and desorption surfactant coefficients on the flow dynamics in wetting, partially wetting and non-wetting droplets are studied in detail. It is observed that the effects of surfactants are more in wetting droplets than in the non-wetting droplets. Further, the presence of surfactants at the contact line reduces the equilibrium contact angle further when θe0 is less than 90°, and increases it further when θe0 is greater than 90°. Nevertheless, the presence of surfactants has no effect on the contact angle when θe0 = 90 °. The numerical study clearly demonstrates that the surfactant-dependent contact angle has to be considered, in addition to the Marangoni effect, in order to study the flow dynamics and the equilibrium states of surfactant

  13. Semi-quantitative determination of cationic surfactants in aqueous solutions using gold nanoparticles as reporter probes.

    Science.gov (United States)

    Kuong, Chi-Lap; Chen, Wei-Yu; Chen, Yu-Chie

    2007-03-01

    Concentrations of cationic surfactants in aqueous solutions have been estimated on the basis of changes in the color of gold nanoparticles, used as reporter probes. We have shown that the colors of gold nanoparticles with anionic protective groups on their surfaces shift from red to indigo/purple and then back to red in a range of cationic surfactant solutions in which concentrations vary from very low to above the theoretical CMCs. The color changes occur near the theoretical CMCs, presumably because the presence of surfactant micelles in the solution prevents the gold nanoparticles from aggregating. We have used gold nanoparticles as reporter probes to determine the concentrations of cationic surfactants in products such as hair conditioners, which often contain large amounts of alkyltrimethylammonium halides. Although this approach can only provide an estimate, it can be performed simply by addition of a given amount of gold nanoparticles to a series of diluted solutions, without the need for instruments or labor-intensive procedures.

  14. 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 cati

  15. Distinct roles of the DmNav and DSC1 channels in the action of DDT and pyrethroids.

    Science.gov (United States)

    Rinkevich, Frank D; Du, Yuzhe; Tolinski, Josh; Ueda, Atsushi; Wu, Chun-Fang; Zhorov, Boris S; Dong, Ke

    2015-03-01

    Voltage-gated sodium channels (Nav channels) are critical for electrical signaling in the nervous system and are the primary targets of the insecticides DDT and pyrethroids. In Drosophila melanogaster, besides the canonical Nav channel, Para (also called DmNav), there is a sodium channel-like cation channel called DSC1 (Drosophila sodium channel 1). Temperature-sensitive paralytic mutations in DmNav (para(ts)) confer resistance to DDT and pyrethroids, whereas DSC1 knockout flies exhibit enhanced sensitivity to pyrethroids. To further define the roles and interaction of DmNav and DSC1 channels in DDT and pyrethroid neurotoxicology, we generated a DmNav/DSC1 double mutant line by introducing a para(ts1) allele (carrying the I265N mutation) into a DSC1 knockout line. We confirmed that the I265N mutation reduced the sensitivity to two pyrethroids, permethrin and deltamethrin of a DmNav variant expressed in Xenopus oocytes. Computer modeling predicts that the I265N mutation confers pyrethroid resistance by allosterically altering the second pyrethroid receptor site on the DmNav channel. Furthermore, we found that I265N-mediated pyrethroid resistance in para(ts1) mutant flies was almost completely abolished in para(ts1);DSC1(-/-) double mutant flies. Unexpectedly, however, the DSC1 knockout flies were less sensitive to DDT, compared to the control flies (w(1118A)), and the para(ts1);DSC1(-/-) double mutant flies were even more resistant to DDT compared to the DSC1 knockout or para(ts1) mutant. Our findings revealed distinct roles of the DmNav and DSC1 channels in the neurotoxicology of DDT vs. pyrethroids and implicate the exciting possibility of using DSC1 channel blockers or modifiers in the management of pyrethroid resistance.

  16. Characterizing crystal disorder of trospium chloride: a comprehensive,(13) C CP/MAS NMR, DSC, FTIR, and XRPD study.

    Science.gov (United States)

    Urbanova, Martina; Sturcova, Adriana; Brus, Jiri; Benes, Hynek; Skorepova, Eliska; Kratochvil, Bohumil; Cejka, Jan; Sedenkova, Ivana; Kobera, Libor; Policianova, Olivia; Sturc, Antonin

    2013-04-01

    Analysis of C cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and X-ray powder diffraction data of trospium chloride (TCl) products crystallized from different mixtures of water-ethanol [φ(EtOH) = 0.5-1.0] at various temperatures (0°C, 20°C) and initial concentrations (saturated solution, 30%-50% excess of solvent) revealed extensive structural variability of TCl. Although (13) C CP/MAS NMR spectra indicated broad variety of structural phases arising from molecular disorder, temperature-modulated DSC identified presence of two distinct components in the products. FTIR spectra revealed alterations in the hydrogen bonding network (ionic hydrogen bond formation), whereas the X-ray diffraction reflected unchanged unit cell parameters. These results were explained by a two-component character of TCl products in which a dominant polymorphic form is accompanied by partly separated nanocrystalline domains of a secondary phase that does not provide clear Bragg reflections. These phases slightly differ in the degree of molecular disorder, in the quality of crystal lattice and hydrogen bonding network. It is also demonstrated that, for the quality control of such complex products, (13) C CP/MAS NMR spectroscopy combined with factor analysis (FA) can satisfactorily be used for categorizing the individual samples: FA of (13) C CP/MAS NMR spectra found clear relationships between the extent of molecular disorder and crystallization conditions. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:1235-1248, 2013.

  17. Cationic surfactants derived from lysine: effects of their structure and charge type on antimicrobial and hemolytic activities.

    Science.gov (United States)

    Colomer, A; Pinazo, A; Manresa, M A; Vinardell, M P; Mitjans, M; Infante, M R; Pérez, L

    2011-02-24

    Three different sets of cationic surfactants from lysine have been synthesized. The first group consists of three monocatenary surfactants with one lysine as the cationic polar head with one cationic charge. The second consists of three monocatenary surfactants with two amino acids as cationic polar head with two positive charges. Finally, four gemini surfactants were synthesized in which the spacer chain and the number and type of cationic charges have been regulated. The micellization process, antimicrobial activity, and hemolytic activity were evaluated. The critical micelle concentration was dependent only on the hydrophobic character of the molecules. Nevertheless, the antimicrobial and hemolytic activities were related to the structure of the compounds as well as the type of cationic charges. The most active surfactants against the bacteria were those with a cationic charge on the trimethylated amino group, whereas all of these surfactants showed low hemolytic character.

  18. Degradation of Surfactants in Hydroponic Wheat Root Zones

    Science.gov (United States)

    Monje, Oscar; McCoy, Lashelle; Flanagan, Aisling

    Hygiene water recycling in recirculating hydroponic systems can be enhanced by plant roots by providing a substrate and root exudates for bacterial growth. However, reduced plant growth can occur during batch mode additions of high concentrations of surfactant. An analog hygiene water stream containing surfactants (Steol CS330, Mirataine CB) was added to a hydroponically-grown wheat plant root zone. The plants were grown at 700 mol mol-1 CO2, a photosynthetic photon flux of 300 mol m-2 s-1, and a planting density of 380 plants m-2. Volumetric oxygen mass transfer coefficients were determined using the fermentative/dynamic outgassing method to maintain adequate oxygen mass transfer rates in the root zone. This analysis suggested an optimal flow rate of the hydroponic solution of 5 L min-1. The hydroponic system was inoculated with biofilm from a bioreactor and rates of surfactant degradation were measured daily based on reduction in chemical oxygen demand (COD). The COD decreased from 400 to 100 mg L-1 after 2 days following batch addition of the analog hygiene water to the hydroponic system. Measurements of dissolved oxygen concentration and solution temperature suggest that the root zone was provided adequate aeration to meet both oxygen demands from plant and microbial respiration during the degradation of the surfactant. Results from this study show that hydroponic systems can be used to enhance rates of hygiene water processing.

  19. REMOVAL OF ORGANIC CHEMICALS FROM WASTEWATER BY SURFACTANT SEPARATION

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    2002-01-01

    This research presents a novel hybrid process for removing organic chemicals from contaminated water. The process uses surfactant to carry out two unit operations (1) Extraction; (2) Foam flotation. In the first step, surfactant is used to extract most of the amounts of organic contaminants in the stream. In the second step, foam flotation is used to further reduce organic contaminants and recover surfactant from the stream. The process combines the advantages of extraction and foam flotation, which allows the process not only to handle a wide range of organic contaminants, but also to effectively treat a wide range of the concentration of organic contaminants in the stream and reduce it to a very low level. Surfactant regeneration can be done by conventional methods. This process is simple and low cost. The wastes are recoverable. The objective of this research is to develop an environmentally innocuous process for the wastewater or reclaimed water treatment with the ability to handle a wide range of organic contaminants, also to effectively treat a wide range of the concentration of organic contaminants in contaminated water and reduce it to a very low level, finally, provides simpler, less energy cost and economically-practical process design. Another purpose is to promote the environmental concern in minority students and encourage minority students to become more involved in environmental engineering research.

  20. A study of polymer-surfactant interactions by neutron reflectivity

    CERN Document Server

    Warren, N

    1999-01-01

    surfactants and their relative levels of interaction with the polymer. The surface behaviour of these systems was observed to be in many ways more remarkable than that of the bulk solution. In the high total surfactant concentration range, once all polymer molecules were associated with bound micelles, the extent of adsorption at the air-liquid interface was found to be dominated largely, as might be expected, by the solution monomer concentrations of the two surfactants. Prior to this, however, adsorption was dominated by the presence of a very surface active polymer-SDS complex which gave rise to enhanced SDS adsorption and low surface tensions compared with those found in polymer-free systems. The origin of this effect, being the stabilisation of the adsorbed SDS monolayer due to a reduction in the inter-headgroup repulsions through screening, by the charged polymer segments, suggests that this may be a characteristic feature of systems continuing a polyelectrolyte and an oppositely charged surfactant. In ...

  1. Effect of anionic-nonionic mixed surfactant on ryegrass uptake of phenanthrene and pyrene from water

    Institute of Scientific and Technical Information of China (English)

    SUN Lu; ZHU LiZhong

    2009-01-01

    The effect of anionic-nonionic mixed surfactant (SDBS-TX100) on the uptake of phenanthrene and pyrene by ryegrass in a hydroponic system was studied, and the influence factors including the com-positions and concentrations of mixed surfactants and the compounds properties were also discussed. The results showed that SDBS-TX100 mixtures with certain compositions and concentrations could enhance the uptake of phenanthrene and pyrene by ryegrass, which could be attributed to the im-proved uptake capacity of ryegrass roots for phenanthrene and pyrene. SDBS-TX100 can enhance the uptake of phenanthrene and pyrene by ryegrass in a wider range of surfactant concentrations (0-0.8 mmol/L) in comparison with corresponding single surfactants, and the maximal contents of phenan-threne and pyrene in ryegrass roots were obtained with the concentrations of SDBS-TX100 around the corresponding critical micelle concentrations. The uptake of phenanthrene and pyrene by ryegrass increased with the increasing mole fraction of SDBS in mixed surfactant solutions, and SDBS-TX100 mixture with a mole ratio of SDBS to TX100 at 9:1 had the greatest capacity in enhancing the uptake of phenanthrene and pyrene, at which the corresponding maximal concentrations of phenanthrene and pyrene in ryegrass roots were 216 and 8.16 times those without surfactants, respectively. Results from this study indicate that the anionic-nonionic mixed surfactants (SDBS-TX100) would be a preferred selection for the application of surfactant-enhanced phytoremediation technology to contaminated soils.

  2. Structure and Dynamics of Nonionic Surfactant Aggregates in Layered Materials.

    Science.gov (United States)

    Guégan, Régis; Veron, Emmanuel; Le Forestier, Lydie; Ogawa, Makoto; Cadars, Sylvian

    2017-09-26

    The aggregation of surfactants on solid surfaces as they are adsorbed from solution is the basis of numerous technological applications such as colloidal stabilization, ore flotation, and floor cleaning. The understanding of both the structure and the dynamics of surfactant aggregates applies to the development of alternative ways of preparing hybrid layered materials. For this purpose, we study the adsorption of the triethylene glycol mono n-decyl ether (C10E3) nonionic surfactant onto a synthetic montmorillonite (Mt), an aluminosilicate clay mineral for organoclay preparation with important applications in materials sciences, catalysis, wastewater treatment, or as drug delivery. The aggregation mechanisms follow those observed in an analogous natural Mt, with the condensation of C10E3 in a bilayer arrangement once the surfactant self-assembles in a lamellar phase beyond the critical micelle concentration, underlining the importance of the surfactant state in solution. Solid-state (1)H nuclear magnetic resonance (NMR) at fast magic-angle spinning (MAS) and high magnetic field combined with(1)H-(13)C correlation experiments and different types of (13)C NMR experiments selectively probes mobile or rigid moieties of C10E3 in three different aggregate organizations: (i) a lateral monolayer, (ii) a lateral bilayer, and (iii) a normal bilayer. High-resolution (1)H{(27)Al} CP-(1)H-(1)H spin diffusion experiments shed light on the proximities and dynamics of the different fragments and fractions of the intercalated surfactant molecules with respect to the Mt surface. (23)Na and (1)H NMR measurements combined with complementary NMR data, at both molecular and nanometer scales, precisely pointed out the location of the C10E3 ethylene oxide hydrophilic group in close contact with the Mt surface interacting through ion-dipole or van der Waals interactions.

  3. Use of Viscosity to Probe the Interaction of Anionic Surfactants with a Coagulant Protein from Moringa oleifera Seeds

    Directory of Open Access Journals (Sweden)

    Raymond Maikokera

    2009-01-01

    Full Text Available The intrinsic viscosity of the coagulant protein was evaluated from the flow times of the protein solutions through a capillary viscometer, and the results suggested the coagulant protein to be globular. The interactions of the coagulant protein with anionic surfactant sodium dodecyl sulphate (SDS and sodium dodecyl benzene sulfonate (SDBS were also investigated by capillary viscometry. We conclude that there is strong protein-surfactant interaction at very low surfactant concentrations, and the behavior of the anionic surfactants in solutions containing coagulant protein is very similar. The viscometry results of protein-SDS system are compared with surface tension, fluorescence, and circular dichroism reported earlier. Combining the results of the four studies, the four approaches seem to confirm the same picture of the coagulant protein-SDS interaction. All the physical quantities when studied as function of surfactant concentration for 0.05% (w/v protein solution either exhibited a maximum or minimum at a critical SDS concentration.

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

    Science.gov (United States)

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

    2004-05-20

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

  5. Interaction of bovine serum albumin with N-acyl amino acid based anionic surfactants: Effect of head-group hydrophobicity.

    Science.gov (United States)

    Ghosh, Subhajit; Dey, Joykrishna

    2015-11-15

    The function of a protein depends upon its structure and surfactant molecules are known to alter protein structure. For this reason protein-surfactant interaction is important in biological, pharmaceutical, and cosmetic industries. In the present work, interactions of a series of anionic surfactants having the same hydrocarbon chain length, but different amino acid head group, such as l-alanine, l-valine, l-leucine, and l-phenylalanine with the transport protein, bovine serum albumin (BSA), were studied at low surfactant concentrations using fluorescence and circular dichroism (CD) spectroscopy, and isothermal titration calorimetry (ITC). The results of fluorescence measurements suggest that the surfactant molecules bind simultaneously to the drug binding site I and II of the protein subdomain IIA and IIIA, respectively. The fluorescence as well as CD spectra suggest that the conformation of BSA goes to a more structured state upon surfactant binding at low concentrations. The binding constants of the surfactants were determined by the use of fluorescence as well as ITC measurements and were compared with that of the corresponding glycine-derived surfactant. The binding constant values clearly indicate a significant head-group effect on the BSA-surfactant interaction and the interaction is mainly hydrophobic in nature.

  6. Heat-regulated foaming in surfactant solutions

    Energy Technology Data Exchange (ETDEWEB)

    Pletnev, M.Y.; Eremina, L.D.; Vlasenko, I.G.

    1984-01-01

    This article examines the mechanism of the foam-inhibiting action resulting from the use of propylene oxide derivatives in solutions both of anionic and of nonionic surfactants. The objective is the creation of a detergent composition with heat-regulated foaming, which would foam well at 30-50/sup 0/ and poorly at 80-90/sup 0/, which is the usual temperature of washing machines. It is demonstrated that foaming can be regulated by the variation of the cloud points of solutions with the aid of additions of polypropylene glycols and their alkyl derivatives or block copolymers in solutions of surfactants. Foaming and foam stability decrease sharply above the cloud points of the solutions due to the foam-inhibiting action of the coacervate phase on the coexisting foam-forming solution. The foam inhibition of polypropylene glycols increases and becomes apparent at lower concentrations with the increase of the average molecular weight of the hydrophobic blocks, the increase of their relative content (in block copolymers with oxyethylene groups), and upon the introduction of alkyl groups.

  7. Investigations into surfactant/gas hydrate relationship

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Rudy; Zhang, Guochang; Dearman, Jennifer; Woods, Charles [Swalm School of Chemical Engineering, Mississippi State University, Mississippi State, MS 39762 (United States)

    2007-03-15

    Gas hydrates have unique physical properties portending useful industrial applications of gas storage, gas separation, or water desalination. When gas hydrates were found in the early 1990s to occur naturally and abundantly in seafloors, three other primary interests and concerns emerged: potential new energy source, climate threat from their greenhouse gases, and seafloor instabilities. This paper presents research showing how anionic synthetic surfactants helped develop an industrial gas hydrate storage process for natural gas and how naturally-occurring in-situ anionic biosurfactants influence the formation and placement of gas hydrates in ocean sediments. The catalytic effects, mechanisms, and surface specificities imparted by synthetic surfactants in the gas storage process and imparted by biosurfactants in porous media are discussed. The Bacillus subtilis bacterium that is indigenous to gas hydrate mounds in the Gulf of Mexico was cultured in the laboratory. Its biosurfactant was separated and found to catalyze gas hydrates in porous media. The experiments indicate that seafloor-biosurfactants can be produced rapidly in-situ to achieve threshold concentrations whereby hydrates are promoted. The biosurfactants accumulate and promote hydrate formation on specific mineral surfaces such as sodium montmorillonite. (author)

  8. Comparison of several ethanol productions using xylanase, inorganic salts, surfactant

    Science.gov (United States)

    Wu, Yan; Lu, Jie; Yang, Rui-feng; Song, Wen-jing; Li, Hai-ming; Wang, Hai-song; Zhou, Jing-hui

    2017-03-01

    Liquid hot water (LHW) pretreatment is an effective and environmentally friendly method to produce bioethanol with lignocellulosic materials. Corn stover was pretreated with liquid hot water (LHW) and then subjected to semi-simultaneous saccharification and fermentation (S-SSF) to obtain high ethanol concentration and yield. The present study aimed to confirm the effect of several additives on the fermentation digestibility of unwashed WIS of corn stover pretreated with LHW. So we also investigated the process, such as enzyme addition, inorganic salts, surfactant and different loading Triton. Results show that high ethanol concentration is necessary to add xylanase in the stage of saccharification. The ethanol concentration increased mainly with magnesium ion on fermentation. Comparing with Tween 80, Span 80 and Polyethylene glycol, Triton is the best surfactant. In contrast to using xylanase and Triton respectively, optimization can make up the lack of stamina and improve effect of single inorganic salts.

  9. Novel Pyridinium Surfactants with Unsaturated Alkyl Chains : Aggregation Behavior and Interactions with Methyl Orange in Aqueous Solution

    NARCIS (Netherlands)

    Kuiper, Johanna M.; Buwalda, Rixt T.; Hulst, Ron; Engberts, Jan B.F.N.

    2001-01-01

    This paper presents the synthesis and a study of the aggregation behavior of 4-undecyl-1-methyl- and 4-undecenyl-1-methylpyridinium iodide surfactants. The effect of the position of the double bond in the alkyl chain of the surfactant on the critical micelle concentration (cmc), degree of counterion

  10. Communication: Light driven remote control of microgels' size in the presence of photosensitive surfactant: Complete phase diagram

    Science.gov (United States)

    Schimka, Selina; Gordievskaya, Yulia D.; Lomadze, Nino; Lehmann, Maren; von Klitzing, Regine; Rumyantsev, Artem M.; Kramarenko, Elena Yu.; Santer, Svetlana

    2017-07-01

    Here we report on a light triggered remote control of microgel size in the presence of photosensitive surfactant. The hydrophobic tail of the cationic surfactant contains azobenzene group that undergoes a reversible photo-isomerization reaction from a trans- to a cis-state accompanied by a change in the hydrophobicity of the surfactant. We have investigated light assisted behaviour and the complex formation of the microgels with azobenzene containing surfactant over the broad concentrational range starting far below and exceeding several times of the critical micelle concentration (CMC). At small surfactant concentration in solution (far below CMC), the surfactant in the trans-state accommodates within the microgel causing its compaction, while the cis-isomer desorbs out of microgel resulting in its swelling. The process of the microgel size change can be described as swelling on UV irradiation (trans-cis isomerization) and shrinking on irradiation with blue light (cis-trans isomerization). However, at the surfactant concentrations larger than CMC, the opposite behaviour is observed: the microgel swells on blue irradiation and shrinks during exposure to UV light. We explain this behaviour theoretically taking into account isomer dependent micellization of surfactant within the microgels.

  11. Systematic investigation of lard polymorphism using combined DSC and time-resolved synchrotron X-ray diffraction

    NARCIS (Netherlands)

    Kalnin, D.J.E.; Lesieur, P.; Artzner, F.; Keller, G.; Ollivon, M.

    2005-01-01

    The polymorphic behavior of lard was systematically investigated by differential scanning calorimetry (DSC) while simultaneously monitoring the formation of the different crystal forms with X-ray diffraction (XRDT). To interpret the complex polymorphic evolution of the sample analyzed by regular DSC

  12. Direct Numerical Simulation of Insoluble Surfactant Effect on Turbulent Channel Bubbly Flows

    Science.gov (United States)

    Lu, Jiacai; Tryggvason, Gretar

    2016-11-01

    Direct Numerical Simulations (DNS) have been successfully used to obtain detailed data for turbulent channel bubbly flows. However, most of DNS that have been done so far remain problematic in comparing to most experiments. One of the major reasons is that real bubbly flows contain surfactants. The surfactants adhere to the interface, and produce an uneven distribution of the surfactant concentration due to the moving of bubbles and result in uneven surface tension over bubble surfaces. In this project, the effect of surfactants on the flow of many bubbles in an upward turbulent channel flow is studied by using of Direct Numerical Simulation with 3D Front-tracking method. The surfactant mass and the interfacial area are directly tracked in the method, and the surfactant mass remains conserved during the evolution. By using of different elasticity numbers in the non-linear equation of state which relates the surface tension to the surfactant concentration, the simulations show that the evolution of the turbulent channel bubbly flow are much different among the cases with contaminated bubbles and clean bubbles. Profiles of many parameters, such as streamwise velocity, shear stress and etc., are also compared at the statistically steady state for these cases. Research supported by DOE (CASL).

  13. Antibacterial Activity, in Vitro Cytotoxicity, and Cell Cycle Arrest of Gemini Quaternary Ammonium Surfactants.

    Science.gov (United States)

    Zhang, Shanshan; Ding, Shiping; Yu, Jing; Chen, Xuerui; Lei, Qunfang; Fang, Wenjun

    2015-11-10

    Twelve gemini quaternary ammonium surfactants have been employed to evaluate the antibacterial activity and in vitro cytotoxicity. The antibacterial effects of the gemini surfactants are performed on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with minimum inhibitory concentrations (MIC) ranging from 2.8 to 167.7 μM. Scanning electron microscopy (SEM) analysis results show that these surfactants interact with the bacterial cell membrane, disrupt the integrity of the membrane, and consequently kill the bacteria. The data recorded on C6 glioma and HEK293 human kidney cell lines using an MTT assay exhibit low half inhibitory concentrations (IC50). The influences of the gemini surfactants on the cell morphology, the cell migration ability, and the cell cycle are observed through hematoxylin-eosin (HE) staining, cell wound healing assay, and flow cytometric analyses, respectively. Both the values of MIC and IC50 decrease against the growth of the alkyl chain length of the gemini surfactants with the same spacer group. In the case of surfactants 12-s-12, the MICs and IC50s are found to decrease slightly with the spacer chain length changing from 2 to 8 and again to increase at higher spacer length (s = 10-12). All of the gemini surfactants show great antibacterial activity and cytotoxicity, and they might exhibit potential applications in medical fields.

  14. 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.

  15. Screening of mixed surfactant systems: Phase behavior studies and CT imaging of surfactant-enhanced oil recovery experiments

    Energy Technology Data Exchange (ETDEWEB)

    Llave, F.M.; Gall, B.L.; Lorenz, P.B.; Cook, I.M.; Scott, L.J.

    1993-11-01

    A systematic chemical screening study was conducted on selected anionic-nonionic and nonionic-nonionic systems. The objective of the study was to evaluate and determine combinations of these surfactants that would exhibit favorable phase behavior and solubilization capacity. The effects of different parameters including (a) salinity, (b) temperature, (c) alkane carbon number, (c) hydrophilic/lipophilic balance (HLB) of nonionic component, and (d) type of surfactant on the behavior of the overall chemical system were evaluated. The current work was conducted using a series of ethoxylated nonionic surfactants in combinations of several anionic systems with various hydrocarbons. Efforts to correlate the behavior of these mixed systems led to the development of several models for the chemical systems tested. The models were used to compare the different systems and provided some guidelines for formulating them to account for variations in salinity, oil hydrocarbon number, and temperature. The models were also evaluated to determine conformance with the results from experimental measurements. The models provided good agreement with experimental results. X-ray computed tomography (CT) was used to study fluid distributions during chemical enhanced oil recovery experiments. CT-monitored corefloods were conducted to examine the effect of changing surfactant slug size injection on oil bank formation and propagation. Reducing surfactant slug size resulted in lower total oil production. Oil recovery results, however, did not correlate with slug size for the low-concentration, alkaline, mixed surfactant system used in these tests. The CT measurements showed that polymer mobility control and core features also affected the overall oil recovery results.

  16. Soap opera : polymer-surfactant interactions on thin film surfaces /

    Energy Technology Data Exchange (ETDEWEB)

    Ozer, B. H. (Byram H.); Johal, M. S. (Malkiat S.); Wang, H. L. (Hsing-Lin); Robinson, J. M. (Jeanne M.)

    2001-01-01

    Surfactants are macromolecules with unique properties. They commonly contain a polar head group with a nonpolar hydrocarbon chain. These properties allow surfactants to solubilize greases and other nonpolar molecules. One particular way that this is accomplished is through the formation of micelles. Micelles are formed at the critical micelle concentration (cmc), which varies depending upon the nature of the surfactant and also the media in which the surfactant resides. These micelles can take a variety of shapes, but are generally characterized by surrounding the grease with the nonpolar hydrocarbon chains, exposing only the polarized head groups to the media, usually water. This property of easy solubilization has made surfactants a very attractive industrial agent, They are used most conventionally as industrial cleaning agents and detergents. However, they also have lesser-known applications in conjunction with polymers and other macromolecular mixtures, often creating a system with novel properties, such as increased solubilization and smoother mixture consistency. A recently developed field has investigated the self-assembly of polymers and polyelectrolytes onto thin film surfaces. There are many reasons for studying this process, such as for second harmonic generation purposes and bioassays. In this study, the interaction between the anionic polyelectrolyte poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) and two surfactants of opposite charge, Sodium Dodecyl Sulfate (SDS) and Dodecyl Trimethyl Ammonium Bromide (DTAB), in their assembly onto thin film surfaces was investigated. The kinetics of adsorbance onto the thin films was examined, followed by construction of 10-bilayer films using an alternating layer of the cationic polyelectrolyte poly(ethylenimine) (PEI) to provide the electrostatic means for the PAZO/surfactant combination to assemble onto the thin film. The kinetics of adsorption is being

  17. Combination of surfactant solubilization with permanganate oxidation for DNAPL remediation.

    Science.gov (United States)

    Li, Zhaohui; Hanlie, Hong

    2008-02-01

    A combination of surfactant solubilization with permanganate oxidation of trichloroethylene (TCE) was studied in batch, flow-through column, and three-dimensional (3-D) tank tests. Batch results showed that chloride production, an indication of TCE degradation, followed a pseudo-first-order reaction kinetics with respect to KMnO4 in the presence of free-phase TCE. A higher chloride production rate was achieved when anionic surfactants were present. The observed pseudo-first-order reaction rate constant increased as the concentrations of anionic surfactants Ninate 411 and Calfax increased from 0% to 0.1%, 0.3%, and 1.0%. Column experiments on TCE reduction by permanganate in the presence and absence of surfactants were carried out using well-sorted coarse Ottawa sand. The peak effluent TCE concentration reached 1700 mg/L due to enhanced solubilization when both sodium dodecyl sulfate (SDS) and permanganate were used, in contrast to less than 300 mg/L when only permanganate solution was used. In addition, the effluent TCE concentration decreased much faster when SDS was present in the permanganate solution, compared with the case when SDS was absent. With an initial 1 mL of TCE emplaced in the columns, the effluent TCE concentration dropped to breakthrough occurred after 21-25 h of injection when SDS was present compared with 45-70 h later when SDS was absent. A slightly higher chloride concentration was observed in the earlier stage of the column experiment and the chloride concentration decreased quickly once KMnO4 was seen in the effluent. The 3-D tank test showed that the MnO2 precipitation front formed more quickly when 1% SDS was present, which further confirmed the observation from the column study.

  18. Synthesis and Surface Activity of Novel Triazole-based Cationic Gemini Surfactants

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The synthesis and surfactant activities of two new cationic gemini surfactants containingtriazole compound as spacer were described. Their critical micelle concentrations (CMC), whichare 1.8 × l0-4 mol/L and 3.9× 10-4 mol/L respectively, are much lower than that of conventionalsurfactant cetyltrimethyl ammonium chloride (CTAC). In addition, compared with some geminisurfactants containing phenylene, xylylene and stilbenyl as spacer, this new kind of surfactants hasgood solubility in water at room temperature because of containing more hydrophilic groups oratoms in molecules.

  19. Effect of alkyl chain asymmetry on catanionic mixtures of hydrogenated and fluorinated surfactants.

    Science.gov (United States)

    Blanco, Elena; Rodriguez-Abreu, Carlos; Schulz, Pablo; Ruso, Juan M

    2010-01-15

    In this work we studied and compared the physicochemical properties of the catanionic mixtures cetyltrimethyl-ammonium bromide-sodium dodecanoate, cetyltrimethyl-ammonium bromide-sodium perfluorodacanoate, octyltrimethylammonium bromide-sodium perfluorodacanoate and cetyltrimethyl-ammonium bromide-sodium octanoate by a combination of rheological, transmission electron microscopy (TEM) and polarized optical microscopy measurements. The binary mixtures of the surfactants have been analyzed at different mixed ratios and total concentration of the mixture. Mixtures containing a perfluorinated surfactant are able to form lamellar liquid crystals and stable spontaneous vesicles. Meanwhile, system containing just hydrogenated surfactants form hexagonal phases or they are arranged in elongated aggregates.

  20. Small angle neutron scattering study of mixed micelles of oppositely charged surfactants

    Indian Academy of Sciences (India)

    J V Joshi; V K Aswal; P S Goyal

    2008-11-01

    Structures of mixed micelles of oppositely charged surfactants dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulphate (SDS) have been studied using small angle neutron scattering. The concentration of one of the components was kept fixed (0.3 M) and that of another varied in the range 0 to 0.1 M. The aggregation number and micellar size increase and fractional charge decreases dramatically with the addition of small amount of oppositely charged surfactant. The effect of addition of SDS on DTAB is significantly different from that of the addition of DTAB on SDS. The contrast variation SANS experiments using deuterated surfactant suggests the homogeneous mixing of two components in mixed micellar system.

  1. Alkyl propoxy ethoxylate "graded" surfactants: micelle formation and structure in aqueous solutions.

    Science.gov (United States)

    Sarkar, Biswajit; Alexandridis, Paschalis

    2010-04-08

    The self-assembly of alkyl propoxy ethoxylate surfactants in aqueous solutions has been investigated with a focus on the (i) thermodynamics of micellization (critical micellization concentration; free energy, enthalpy, and entropy of micellization) and (ii) structure of the micelles (overall shape and size; local environment in the micelle core and corona) as affected by the surfactant composition (variation of degree of ethoxylation). The various results are compared to those for alkyl ethoxylate and poly(ethylene oxide)-b-poly(propylene oxide) amphiphiles with the aim to elucidate the role of the middle, propoxy, block in the novel alkyl propoxy ethoxylate surfactants which exhibit a "graded" hydrophobic-hydrophilic character.

  2. An anionic surfactant for EOR applications

    Science.gov (United States)

    Sagir, Muhammad; Tan, Isa M.; Mushtaq, Muhammad

    2014-10-01

    This work is to investigate the new anionic surfactants for the Enhanced Oil Recovery (EOR) application. Sulfonated anionic surfactant was produced by attaching SO3 to an ethoxylated alcohol to increase the performance of the surfactant. Methallyl chloride and ethoxylated alcohol was reacted followed by the reaction with sodium bisulfite to produce anionic sulfonated surfactant in 80.3 % yield. The sulfonation reaction parameters such as reactants mole ratio, reaction temperature and catalyst amount were optimized. The generation and stability of foam from the synthesized surfactant is also tested and results are reported. The synthesized novel surfactant was further investigated for the effect on the CO2 mobility in porous media and the findings are presented here. This in house developed surfactant has a great potential for CO2- EOR applications.

  3. Dynamic interfacial behavior of decyl methylnaphthalene sulfonate surfactants for enhanced oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Zhongkui; Ba Yan; Li Zongshi; Qiao Weihong; Cheng Luebai [State Key Lab. of Fine Chemicals, Dalian Univ. of Technology, Dalian (China)

    2004-10-01

    The high purity decyl methylnaphthalene sulfonate (DMNS) was synthesized, the purity was determined by HPLC and the structure was confirmed by IR, UV and ESI-MS. Dynamic interfacial tensions (DIT) between DMNS flooding systems and crude oil were measured and the effects of sodium carbonate concentration, surfactant concentration and sodium chloride concentration on the DIT behaviors were investigated. It's found that the surfactant concentration, alkali concentration and the salinity have obvious influences on DIT behaviors. DMNS possessed outstanding capacity and efficiency of lowering the DIT between oil and water. The minimum dynamic interfacial tension could reach 6.35 x 10{sup -6} mNm{sup -1} at a low concentration for added surfactant. DMNS might be used in Enhanced Oil Recovery with low costs and high efficiency. (orig.)

  4. Aqueous Foams Stabilized by Hydrophilic Silica Nanoparticles via In-Situ Physisorption of Nonionic TX100 Surfactant

    Directory of Open Access Journals (Sweden)

    Suriatie Yusuf

    2013-01-01

    Full Text Available This paper present the study of aqueous CO foam prepared 2 by a mixtures hydrophilic silica nanoparticles and non-ionic Triton X100, TX100, surfactant. The synergistic effects of the mixture on stabilizing the CO2 foam were inferred into few key parameters namely; particles and surfactant concentration, adsorption of surfactant onto the particles via surface tension and adsorption isotherm, foam lifetime and, the size of the bubbles produced. It was found that the adsorption behaviour of TX100 on silica surface exhibit a particular characteristics depend on the concentration of silica, high total surface area available leads to high adsorptionof surfactant molecules. The synergetic performance of silica/TX100 in stabilizing foam can be observed at low (0.01% and intermediate (0.1% concentration of TX100. Lower concentration required low silica concentration while the intermediate concentration required high silica fraction in the dispersion to stabilize the foam.

  5. Low Complexity DCT-based DSC approach forHyperspectral Image Compression with Arithmetic Code

    Directory of Open Access Journals (Sweden)

    Meena Babu Vallakati

    2012-09-01

    Full Text Available This paper proposes low complexity codec for lossy compression on a sample hyperspectral image. These images have two kinds of redundancies: 1 spatial; and 2 spectral. A discrete cosine transform (DCT- based Distributed Source Coding(DSC paradigm with Arithmetic code for low complexity is introduced. Here, Set-partitioning based approach is applied to reorganize DCT coefficients into wavelet like tree structure as Setpartitioning works on wavelet transform, and extract the sign, refinement, and significance bitplanes. The extracted refinement bits are Arithmetic encoded, then by applying low density parity check based (LDPC-based Slepian-Wolf coder is implement to our DSC strategy. Experimental results for SAMSON (Spectroscopic Aerial Mapping System with Onboard Navigation data show that proposed scheme achieve peak signal to noise ratio and compression to a very good extent for water cube compared to building, land or forest cube.

  6. In-situ study of the thermal properties of hydrate slurry by high pressure DSC

    Energy Technology Data Exchange (ETDEWEB)

    Sari, O.; Hu, J.; Brun, F.; Erbeau, N. [Institute of Thermal Engineering, University of Applied Sciences of Western Switzerland, Yverdon-les-Bains (Switzerland); Homsy, P. [Nestec, Vevey (Switzerland); Logel, J.-C. [Axima Refrigeration, Bischheim (France)

    2008-07-01

    Knowing the enthalpy of hydrate slurry is very essential for energy balance and industrial applications. No direct measurement processes had been developed in this field in the past time. A new experimental method with special device has been developed to carry out on-line measurement of the thermal properties for hydrate slurry under dynamic conditions. With this special device, it is possible to deliver the hydrate slurry to the high pressure DSC (Differential Scanning Calorimetry) directly from the production tank or pipes. Thermal data acquisition will be performed afterwards by DSC. The investigated conditions were at pressure of 30 bar and temperature of {approx}+7 {sup o}C. The dissociation enthalpy of CO{sub 2} hydrate slurry was about 54 kJ/kg, corresponding 10.8% of solid fraction. The on-line measurement results for CO{sub 2} hydrate slurry give a good tendency to apply this phase change slurry to the industrial refrigeration process. (author)

  7. In Situ Stability of Substrate-Associated Cellulases Studied by DSC

    DEFF Research Database (Denmark)

    Borch, Kim; Cruys-Bagger, Nicolaj; Badino, Silke Flindt

    2014-01-01

    . There was no correlation between the intrinsic stability, specified by the transition temperature in the DSC, and the long-term stability derived from the peak area. The results are discussed with respect to the role of enzyme denaturation for the ubiquitous slowdown observed in the enzymatic hydrolysis of cellulose.......This work shows that differential scanning calorimetry (DSC) can be used to monitor the stability of substrate-adsorbed cellulases during long-term hydrolysis of insoluble cellulose. Thermal transitions of adsorbed enzyme were measured regularly in subsets of a progressing hydrolysis, and the size...... of the transition peak was used as a gauge of the population of native enzyme. Analogous measurements were made for enzymes in pure buffer. Investigations of two cellobiohydrolases, Cel6A and Cel7A, from Trichoderma reesei, which is an anamorph of the fungus Hypocrea jerorina, showed that these enzymes were...

  8. Characterization of the polycaprolactone melt crystallization: complementary optical microscopy, DSC, and AFM studies.

    Science.gov (United States)

    Speranza, V; Sorrentino, A; De Santis, F; Pantani, R

    2014-01-01

    The first stages of the crystallization of polycaprolactone (PCL) were studied using several techniques. The crystallization exotherms measured by differential scanning calorimetry (DSC) were analyzed and compared with results obtained by polarized optical microscopy (POM), rheology, and atomic force microscope (AFM). The experimental results suggest a strong influence of the observation scale. In particular, the AFM, even if limited on time scale, appears to be the most sensitive technique to detect the first stages of crystallization. On the contrary, at least in the case analysed in this work, rheology appears to be the least sensitive technique. DSC and POM provide closer results. This suggests that the definition of induction time in the polymer crystallization is a vague concept that, in any case, requires the definition of the technique used for its characterization.

  9. Kinetics of the thermal degradation of Erica arborea by DSC: Hybrid kinetic method

    CERN Document Server

    Cancellieri, Dominique; Rossi, Jean Louis; 10.1016/j.tca.2005.07.013

    2008-01-01

    The scope of this work was the determination of kinetic parameters of the thermal oxidative degradation of a Mediterranean scrub using a hybrid method developed at the laboratory. DSC and TGA were used in this study under air sweeping to record oxidative reactions. Two dominating and overlapped exothermic peaks were recorded in DSC and individualized using an experimental and numerical separation. This first stage allowed obtaining the enthalpy variation of each exothermic phenomenon. In a second time, a model free method was applied on each isolated curve to determine the apparent activation energies. A reactional kinetic scheme was proposed for the global exotherm composed of two independent and consecutive reactions. In fine mean values of enthalpy variation and apparent activation energy previously determined were injected in a model fitting method to obtain the reaction order and the preexponential factor of each oxidative reaction. We plan to use these data in a sub-model to be integrated in a wildland ...

  10. Thermal degradation of ligno-cellulosic fuels: DSC and TGA studies

    CERN Document Server

    Leroy, Valérie; Leoni, Eric; 10.1016/j.tca.2006.09.017

    2008-01-01

    The scope of this work was to show the utility of thermal analysis and calorimetric experiments to study the thermal oxidative degradation of Mediterranean scrubs. We investigated the thermal degradation of four species; DSC and TGA were used under air sweeping to record oxidative reactions in dynamic conditions. Heat released and mass loss are important data to be measured for wildland fires modelling purpose and fire hazard studies on ligno-cellulosic fuels. Around 638 and 778 K, two dominating and overlapped exothermic peaks were recorded in DSC and individualized using a experimental and numerical separation. This stage allowed obtaining the enthalpy variation of each exothermic phenomenon. As an application, we propose to classify the fuels according to the heat released and the rate constant of each reaction. TGA experiments showed under air two successive mass loss around 638 and 778 K. Both techniques are useful in order to measure ignitability, combustibility and sustainability of forest fuels.

  11. Comparing Single-Point and Multi-point Calibration Methods in Modulated DSC

    Energy Technology Data Exchange (ETDEWEB)

    Van Buskirk, Caleb Griffith [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-14

    Heat capacity measurements for High Density Polyethylene (HDPE) and Ultra-high Molecular Weight Polyethylene (UHMWPE) were performed using Modulated Differential Scanning Calorimetry (mDSC) over a wide temperature range, -70 to 115 °C, with a TA Instruments Q2000 mDSC. The default calibration method for this instrument involves measuring the heat capacity of a sapphire standard at a single temperature near the middle of the temperature range of interest. However, this method often fails for temperature ranges that exceed a 50 °C interval, likely because of drift or non-linearity in the instrument's heat capacity readings over time or over the temperature range. Therefore, in this study a method was developed to calibrate the instrument using multiple temperatures and the same sapphire standard.

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

    Science.gov (United States)

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

    2015-01-01

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

  13. MICELLAR PARAMETERS OF DIBLOCK COPOLYMERS AND THEIR INTERACTIONS WITH IONIC SURFACTANTS

    Institute of Scientific and Technical Information of China (English)

    Noor Rehman; Abbas Khan; Iram Bibi; Mohammad Siddiq

    2012-01-01

    The interactions of non-ionic amphiphilic diblock copolymer poly(oxyethylene/oxybutylene) (E39B18) with anionic surfactant sodium dodecyl sulphate (SDS) and cationic surfactant hexadecyltrimethylammonium bromide (CTAB) were studied by using various techniques such as surface tension,conductivity,steady-state fluorescence and dynamic light scattering.Surface tension measurements were used to determine the critical micelle concentration (CMC) and thereby the free energy of micellization (AGmic),free energy of adsorption (AGads),surface excess concentration (F) and minimum area per molecule (A).Conductivity measurements were used to determine the critical micelle concentration (CMC),critical aggregation concentration (CAC),polymer saturation point (PSP),degree of ionization (α) and counter ion binding (β).Dynamic light scattering experiments were performed to check the changes in physiochemical properties of the block copolymer micelles taken place due to the interactions of diblock copolymers with ionic surfactants.The ratio of the first and third vibronic peaks (I1/I13) indicated the polarity of the pyrene micro environment and was used for the detection of micelle as well as polymer-surfactant interactions.Aggregation number (N),number of binding sites (n) and free energy of binding (AGb) for pure surfactants as well as for polymer-surfactant mixed micellar systems were determined by the fluorescence quenching method.

  14. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-09-01

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

  16. Droplet Deformation in an Extensional Flow: The Role of Surfactant Physical Chemistry

    Science.gov (United States)

    Stebe, Kathleen J.

    1996-01-01

    Surfactant-induced Marangoni effects strongly alter the stresses exerted along fluid particle interfaces. In low gravity processes, these stresses can dictate the system behavior. The dependence of Marangoni effects on surfactant physical chemistry is not understood, severely impacting our ability to predict and control fluid particle flows. A droplet in an extensional flow allows the controlled study of stretching and deforming interfaces. The deformations of the drop allow both Marangoni stresses, which resist tangential shear, and Marangoni elasticities, which resist surface dilatation, to develop. This flow presents an ideal model system for studying these effects. Prior surfactant-related work in this flow considered a linear dependence of the surface tension on the surface concentration, valid only at dilute surface concentrations, or a non-linear framework at concentrations sufficiently dilute that the linear approximation was valid. The linear framework becomes inadequate for several reasons. The finite dimensions of surfactant molecules must be taken into account with a model that includes surfaces saturation. Nonideal interactions between adsorbed surfactant molecules alter the partitioning of surfactant between the bulk and the interface, the dynamics of surfactant adsorptive/desorptive exchange, and the sensitivity of the surface tension to adsorbed surfactant. For example, cohesion between hydrocarbon chains favors strong adsorption. Cohesion also slows the rate of desorption from interfaces, and decreases the sensitivity of the surface tension to adsorbed surfactant. Strong cohesive interactions result in first order surface phase changes with a plateau in the surface tension vs surface concentration. Within this surface concentration range, the surface tension is decoupled from surface concentration gradients. We are engaged in the study of the role of surfactant physical chemistry in determining the Marangoni stresses on a drop in an extensional

  17. 索尼DSC-S85数码相机试用记

    Institute of Scientific and Technical Information of China (English)

    杨明

    2003-01-01

    @@ Cyber-shot DSC-S85是索尼公司于2001年推出的第一款410万像素Super HAD CCD的数码照相机,但其太传统化的外形设计,几度要毁掉我购买它的信心,不过最终还是把它抱回家,因为是它的品质打动我.

  18. Characterization of surfactant effects on the visible spectroscopy of lanthanide metal ion-triphenylmethane dye complexes

    Energy Technology Data Exchange (ETDEWEB)

    Klopf, G.J.

    1985-01-01

    To better define the mechanism responsible for sensitization, the interactions of representative cationic, anionic, and nonionic surfactants with several lanthanide metal ion-triphenylmethane dye complexes, particularly the gadolinium (Gd/sup +3/)-Chromeazurol S (CAS) complex, were characterized. Only cationic surfactants induced sensitization when added to the Gd/sup +3/-CAS complex. Sensitization induced by cetylpyridinium chloride (CPC) occurred at submicellar concentrations and was attributed to the formation of a 1:2:4 Gd/sup +3/-CAS-CPC ternary complex. Additional ternary complexes evidently form if excess CAS is present. Mechanisms are proposed for the sensitization of the reaction by quaternary compounds and by anionic surfactants. Although both micellar and submicellar concentrations were considered, adding the nonionic surfactant Triton X-100 to the Gd/sup +3/-CAS complex had little effect.

  19. A SURFACTANT-ASSISTED APPROACH FOR PREPARING COLLOIDAL AZO POLYMER SPHERES WITH NARROW SIZE DISTRIBUTION

    Institute of Scientific and Technical Information of China (English)

    Xiao-lan Tong; Yao-bang Li; Ya-ning He; Xiao-gong Wang

    2006-01-01

    A surfactant-assisted method for preparing colloidal spheres with narrow size distribution from a polydispersed azo polymer has been developed in this work. The colloidal spheres were formed through gradual hydrophobic aggregation