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Sample records for adsorbed surfactant layers

  1. Rupture force of adsorbed self-assembled surfactant layers. Effect of the dielectric exchange force

    NASA Astrophysics Data System (ADS)

    Teschke, O.; Ceotto, G.; de Souza, E. F.

    2001-08-01

    The tip applied force necessary to obtain tip/substrate contact, i.e., rupture force between adsorbed layers of self-assembled surfactant films and atomic force microscope (AFM) tips in water has been measured. A substantial contribution of this rupture force is due to the dielectric exchange force (DEF). The DEF model is in agreement with the observation that the surfactant layer rupture forces are smaller in the thickest layers, where the compactness of the adsorbed film results in the smallest values of the dielectric permittivity. Within experimental accuracy a dielectric permittivity value of ˜4 for bilayers and of ˜36 for monolayers is found.

  2. Coalescence behavior of oil droplets coated in irreversibly-adsorbed surfactant layers.

    PubMed

    Reichert, Matthew D; Walker, Lynn M

    2015-07-01

    Coalescence between oil caps with irreversibly adsorbed layers of nonionic surfactant is characterized in deionized water and electrolyte solution. The coalescence is characterized using a modified capillary tensiometer allowing for accurate measurement of the coalescence time. Results suggest two types of coalescence behavior, fast coalescence at low surface coverages that are independent of ionic strength and slow coalescence at high coverage. These slow coalescence events (orders of magnitude slower) are argued to be due to electric double layer forces or more complicated stabilization mechanisms arising from interfacial deformation and surface forces. A simple film drainage model is used in combination with measured values for interfacial properties to quantify the interaction potential between the two interfaces. Since this approach allows the two caps to have the same history, interfacial coverage and curvature, the results offer a tool to better understand a mechanism that is important to emulsion stability.

  3. Adsorption isotherms and structure of cationic surfactants adsorbed on mineral oxide surfaces prepared by atomic layer deposition.

    PubMed

    Wangchareansak, Thipvaree; Craig, Vincent S J; Notley, Shannon M

    2013-12-01

    The adsorption isotherms and aggregate structures of adsorbed surfactants on smooth thin-film surfaces of mineral oxides have been studied by optical reflectometry and atomic force microscopy (AFM). Films of the mineral oxides of titania, alumina, hafnia, and zirconia were produced by atomic layer deposition (ALD) with low roughness. We find that the surface strongly influences the admicelle organization on the surface. At high concentrations (2 × cmc) of cetyltrimethylammonium bromide (CTAB), the surfactant aggregates on a titania surface exhibit a flattened admicelle structure with an average repeat distance of 8.0 ± 1.0 nm whereas aggregates on alumina substrates exhibit a larger admicelle with an average separation distance of 10.5 ± 1.0 nm. A wormlike admicelle structure with an average separation distance of 7.0 ± 1.0 nm can be observed on zirconia substrates whereas a bilayered aggregate structure on hafnia substrates was observed. The change in the surface aggregate structure can be related to an increase in the critical packing parameter through a reduction in the effective headgroup area of the surfactant. The templating strength of the surfaces are found to be hafnia > alumina > zirconia > titania. Weakly templating surfaces are expected to have superior biocompatibility.

  4. Interactions of organic contaminants with mineral-adsorbed surfactants

    USGS Publications Warehouse

    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.

  5. Interactions of organic contaminants with mineral-adsorbed surfactants.

    PubMed

    Zhu, Lizhong; Chen, Baoliang; Tao, Shu; Chiou, Cary T

    2003-09-01

    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 insightto 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.

  6. Selection and evaluation of adsorbents for the removal of anionic surfactants from laundry rinsing water.

    PubMed

    Schouten, Natasja; van der Ham, Louis G J; Euverink, Gert-Jan W; de Haan, André B

    2007-10-01

    Low-cost adsorbents were tested to remove anionic surfactants from laundry rinsing water to allow re-use of water. Adsorbents were selected corresponding to the different surfactant adsorption mechanisms. Equilibrium adsorption studies of linear alkyl benzene sulfonate (LAS) show that ionic interaction results in a high maximum adsorption capacity on positively charged adsorbents of 0.6-1.7 gLAS/g. Non-ionic interactions, such as hydrophobic interactions of LAS with non-ionic resins or activated carbons, result in a lower adsorption capacity of 0.02-0.6 gLAS/g. Negatively charged materials, such as cation exchange resins or bentonite clay, have negligible adsorption capacities for LAS. Similar results are obtained for alpha olefin sulfonate (AOS). Cost comparison of different adsorbents shows that an inorganic anion exchange material (layered double hydroxide) and activated carbons are the most cost-effective materials in terms of the amount of surfactant adsorbed per dollar worth of adsorbent.

  7. Dielectric exchange-force effect on the rupture force of adsorbed bilayers of self-assembled surfactant films

    NASA Astrophysics Data System (ADS)

    Teschke, O.; Ceotto, G.; de Souza, E. F.

    2001-05-01

    We measured and formulated dielectric exchange forces between adsorbed layers of self-assembled surfactant films and atomic-force microscope tips in water. The dielectric exchange-force model is in agreement with the observation that the surfactant-layer rupture forces (tip-applied force necessary to obtain tip/substrate contact) are smaller in the thickest layers, where the compactness of the adsorbed film results in the smallest values of the dielectric permittivity. Within experimental accuracy, a dielectric permittivity value of ˜4 for bilayers and of ˜36 for monolayers is found.

  8. Novel surfactant-based adsorbent material for groundwater remediation.

    PubMed

    Venditti, F; Angelico, R; Ceglie, A; Ambrosone, L

    2007-10-01

    Many surfactants aggregate spontaneously in aqueous media to form small spherical structures called micelles. Among the numerous technical applications it is known that micelles have the ability to dissolve in their hydrophobic part significant amounts of water-insoluble organic compounds. In this study we investigated through UV-vis spectroscopy the micellar solubilization of 2,4,5-trichlorophenol (Tcp), an intermediate product of the microbial degradation of the broad-leaf herbicide 2,4,5-trichlorophenoxyacetic (2,4,5-T). Our results show that in the presence of the anionic surfactant sodium dodecylsulfate SDS the water solubility of Tcp increases six-fold whereas with cationic CTAB and nonionic Triton-X 100 the partition of chlorinated compound is not efficient. After the excess amount of the pollutant solubilized in SDS-micelles has been precipitated with CaCl2 the remaining fraction of Tcp has been successfully reduced within the toxicological limit for drinkable water through a cocurrent multistage operation. Finally, potential use in the decontamination of wastewater or soils of the new adsorbent material has been compared with the most commonly used activated carbon and silica gel.

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

    PubMed

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

    2012-01-17

    Because covalent chemistry can diminish the optical and electronic properties of single-walled carbon nanotubes (SWCNTs), there is significant interest in developing methods of controllably functionalizing the nanotube sidewall. To date, most attempts at obtaining such control have focused on reaction stoichiometry or strength of oxidative treatment. Here, we examine the role of surfactants in the chemical modification of single-walled carbon nanotubes with aryl diazonium salts. The adsorbed surfactant layer is shown to affect the diazonium derivatization of carbon nanotubes in several ways, including electrostatic attraction or repulsion, steric exclusion, and direct chemical modification of the diazonium reactant. Electrostatic effects are most pronounced in the cases of anionic sodium dodecyl sulfate and cationic cetyltrimethylammonium bromide, where differences in surfactant charge can significantly affect the ability of the diazonium ion to access the SWCNT surface. For bile salt surfactants, with the exception of sodium cholate, we find that the surfactant wraps tightly enough such that exclusion effects are dominant. Here, sodium taurocholate exhibits almost no reactivity under the explored reaction conditions, while for sodium deoxycholate and sodium taurodeoxycholate, we show that the greatest extent of reaction is observed among a small population of nanotube species, with diameters between 0.88 and 0.92 nm. The anomalous reaction of nanotubes in this diameter range seems to imply that the surfactant is less effective at coating these species, resulting in a reduced surface coverage on the nanotube. Contrary to the other bile salts studied, sodium cholate enables high selectivity toward metallic species and small band gap semiconductors, which is attributed to surfactant-diazonium coupling to form highly reactive diazoesters. Further, it is found that the rigidity of anionic surfactants can significantly influence the ability of the surfactant layer to

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

    PubMed

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

    2012-01-17

    Because covalent chemistry can diminish the optical and electronic properties of single-walled carbon nanotubes (SWCNTs), there is significant interest in developing methods of controllably functionalizing the nanotube sidewall. To date, most attempts at obtaining such control have focused on reaction stoichiometry or strength of oxidative treatment. Here, we examine the role of surfactants in the chemical modification of single-walled carbon nanotubes with aryl diazonium salts. The adsorbed surfactant layer is shown to affect the diazonium derivatization of carbon nanotubes in several ways, including electrostatic attraction or repulsion, steric exclusion, and direct chemical modification of the diazonium reactant. Electrostatic effects are most pronounced in the cases of anionic sodium dodecyl sulfate and cationic cetyltrimethylammonium bromide, where differences in surfactant charge can significantly affect the ability of the diazonium ion to access the SWCNT surface. For bile salt surfactants, with the exception of sodium cholate, we find that the surfactant wraps tightly enough such that exclusion effects are dominant. Here, sodium taurocholate exhibits almost no reactivity under the explored reaction conditions, while for sodium deoxycholate and sodium taurodeoxycholate, we show that the greatest extent of reaction is observed among a small population of nanotube species, with diameters between 0.88 and 0.92 nm. The anomalous reaction of nanotubes in this diameter range seems to imply that the surfactant is less effective at coating these species, resulting in a reduced surface coverage on the nanotube. Contrary to the other bile salts studied, sodium cholate enables high selectivity toward metallic species and small band gap semiconductors, which is attributed to surfactant-diazonium coupling to form highly reactive diazoesters. Further, it is found that the rigidity of anionic surfactants can significantly influence the ability of the surfactant layer to

  11. Surfactant induced aggregation behavior of Merocyanine-540 adsorbed on polymer coated positively charged gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Das, K.; Uppal, A.; Saini, R. K.

    2016-01-01

    Surfactant induced aggregation behavior of Merocyanine 540 adsorbed on polymer (PDD) coated gold nanoparticles (AuNP) is reported. The absorption band of the dye shifts to higher energy in the presence of free polymer and polymer coated AuNP implying aggregation. Addition of a negatively charged surfactant (SDS) induces multiple bands in the extinction spectrum of the dye adsorbed on nanoparticle surface. The highest (460 nm) and lowest (564 nm) energy bands of the dye become prominent at 10 and >50 μM SDS concentrations respectively (dye: 10 μM; AuNP: 100-200 pM). Based on earlier results the high energy band is likely to originate from dye aggregates and the low energy band is likely to originate from dye monomers. This is attributed to the interplay between polymer-surfactant and polymer-dye interactions at the AuNP surface. The extinction spectra of dye adsorbed at AuNP surface remain unaffected in the presence of a positively charged (CTAB) or a neutral surfactant (Tx-100), at low surfactant concentrations. However at higher surfactant concentrations (>60 μM) dye aggregation takes place which is attributed to dye-surfactant interactions. The fluorescence intensity of the dye quenched significantly but its lifetime increased in the presence of polymer coated AuNP. This is attributed to aggregation and reduction in the photoisomerization rate of the dye adsorbed on AuNP surface.

  12. Adsorption of high salinity surfactant systems and sacrificial agents for EOR on model adsorbents

    SciTech Connect

    Volz, H.V.

    1988-05-01

    In chemical flooding processes for enhanced oil recovery, chemical adsorption is a major factor which may limit the applicability of these processes. Under typical high salinity conditions of West German oil reservoirs (100 to 200 kg/m/sup 3/ of total dissolved solids) adsorption experiments with single and multi-component surfactant systems and with and without the use of sacrificial agents on model adsorbents were carried out, adsorbents being calcium benetonite, illite, kaolinite, dickite, prochlorite, and quartz. It can be shown that polyethylene glycols of appropriate molecular weight, which were used as sacrificial agents, adsorb specifically on calcium bentonite or quartz, whereas on kaolnite they form an adsorbing complex together with the surfactant. Based on experimental results specific coverages of sacrificial agents and surfactants are calculated.

  13. Dynamics of surfactants spreading on gel layers

    NASA Astrophysics Data System (ADS)

    Spandagos, Constantine; Luckham, Paul; Matar, Omar

    2009-11-01

    Gel-like materials are of central importance to a large number of engineering, biological, biomedical and day-life applications. This work attempts to investigate the spreading of droplets of surfactant solutions on agar gels, which is accompanied by cracking of the gel layers. The cracking progresses via the formation of patterns that resemble ``starbursts,'' which have been reported recently in the literature by Daniels et al. Marangoni stresses generated by surface tension gradients between the surfactant droplet and the uncontaminated gel layer are identified to be the driving force behind these phenomena. The morphology and dynamics of the starburst patterns are investigated for droplets of different surfactant solutions, including sodiumdodecylsulphate, spreading on gel layers of different strengths. The instability is characterised in terms of the number of arms that form, and their mean width and length as a function of time. In addition, photoelasticity is used to provide information about the stress field of the material, which, combined with the results from our direct visualisation, can elucidate further the mechanisms underlying the pattern formation and the nature of the interactions between the liquid and the gel.

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

    DOEpatents

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

    1980-08-20

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

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

    DOEpatents

    Johnson, Jr., James S.; Westmoreland, Clyde G.

    1982-01-01

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

  16. Structural rearrangements in self-assembled surfactant layers at surfaces

    SciTech Connect

    Sushko, Maria L.; Liu, Jun

    2010-03-25

    The transition from compact to extended configuration in ionic surfactant layers under the influence of salt, surfactant surface density and temperature is studied using the classical density functional theory (cDFT). The increase in ionic strength of aqueous salt solution or in surfactant surface density leads to the transition from the hemicylindrical to the perpendicular monolayer configuration of the molecules. Although producing the same structural rearrangement in the surfactant layer the origin of the effect of salt and surface density is different. While the addition of salt increases the out-of-plane attractive interactions with the solvent, the increase in density results in the increase in the in-plane repulsion in surfactant layer. The temperature effects are subtler and are mainly manifested in the reduction of the solution structuring at elevated temperatures.

  17. Microemulsions: Structures, surfactant layer properties and wetting transitions

    NASA Astrophysics Data System (ADS)

    Abillon, O.; Lee, L. T.; Langevin, D.; Wong, K.

    1991-03-01

    We review briefly the basic known features of microemulsion structures, emphasizing the importance of the surfactant layer bending elasticity. The results for water-alkane-nonionic-surfactant systems, confirming the close relationship between the maximum characteristic size in the microemulsion and the persistence length of the surfactant layer, are presented. We show that microemulsions are formed when the surfactant layer bending moduli are in a well defined range: if the bending modulus is too large, ordered lamellar phases are obtained, while if it is too small, the surfactant film cannot form, and the medium is a structureless molecular mixture. The evolution between microemulsions and molecular mixtures is continuous; its relationship with the wetting transition between the microemulsion and the two excess phases is discussed.

  18. Bending elasticity of charged surfactant layers: the effect of mixing.

    PubMed

    Bergström, L Magnus

    2006-08-01

    Expressions have been derived from which the spontaneous curvature (H(0)), bending rigidity (k(c)), and saddle-splay constant (k(c)) of mixed monolayers and bilayers may be calculated from molecular and solution properties as well as experimentally available quantities such as the macroscopic hydrophobic-hydrophilic interfacial tension. Three different cases of binary surfactant mixtures have been treated in detail: (i) mixtures of an ionic and a nonionic surfactant, (ii) mixtures of two oppositely charged surfactants, and (iii) mixtures of two ionic surfactants with identical headgroups but different tail volumes. It is demonstrated that k(c)H(0), k(c), and k(c) for mixtures of surfactants with flexible tails may be subdivided into one contribution that is due to bending properties of an infinitely thin surface as calculated from the Poisson-Boltzmann mean field theory and one contribution appearing as a result of the surfactant film having a finite thickness with the surface of charge located somewhat outside the hydrophobic-hydrophilic interface. As a matter of fact, the picture becomes completely different as finite layer thickness effects are taken into account, and as a result, the spontaneous curvature is extensively lowered whereas the bending rigidity is raised. Furthermore, an additional contribution to k(c) is present for surfactant mixtures but is absent for k(c)H(0) and k(c). This contribution appears as a consequence of the minimization of the free energy with respect to the composition of a surfactant layer that is open in the thermodynamic sense and must always be negative (i.e., k(c) is generally found to be brought down by the process of mixing two or more surfactants). The magnitude of the reduction of k(c) increases with increasing asymmetry between two surfactants with respect to headgroup charge number and tail volume. As a consequence, the bending rigidity assumes the lowest values for layers formed in mixtures of two oppositely charged

  19. Possible role of adsorbed surfactant in controlling membrane permeability and function.

    PubMed

    Hills, B A

    1989-02-01

    It is well established in the physical sciences that the adsorption of a monolayer of certain surfactants onto the surface of a synthetic membrane used for ultrafiltration can greatly modify its permeability to water and its ability to transmit small solute molecules and ions of physiological interest. In this hypothesis, it is proposed that, when indigenous surfactant is adsorbed to certain membranes in the body, it can similarly modify their permeability. Since adsorption can be a rapidly reversible process, this would provide a simple physical means of controlling the overall level of physiological activity of the membrane and, possibly, an additional means of differentiating membranes according to function. The hypothesis raises many questions concerning its applicability to the general structure of biological membranes, the nature of the surfactant, its ability to adsorb to solid surfaces and the reasons why such a coating may have been missed. There are then the questions of which membranes might benefit most and what happens if the coating is too sparse or is removed unintentionally.

  20. In situ investigation into surfactant effects on the clearance of polycyclic aromatic hydrocarbons adsorbed onto soybean leaf surfaces.

    PubMed

    Sun, Haifeng; Wang, Weipeng; Guo, Shuai; Zhang, Yong

    2016-03-01

    The partitioning of polycyclic aromatic hydrocarbons (PAHs) in agricultural crop leaves, contributes to the exposure of organisms to these chemicals through the dietary pathway. To precisely predict the fate of PAHs and crop safety, the clearance of three-ringed phenanthrene (Phe) and four-ringed pyrene (Pyr) adsorbed individually onto living soybean leaf surfaces, as well as the effects of two surfactants, namely, an ionic surfactant (sodium dodecylbenzene sulfonate, SDBS) and a non-ionic surfactant (polyoxyethyleneglycol dodecyl ether, Brij35), were investigated in situ using the laser-induced nanosecond time-resolved fluorescence (LITRF) method. The effects varied significantly with surfactant types primarily in terms of the elimination rates and the final residues of PAH chemicals. With increasing SDBS and Brij35 concentrations, volatilization rate constants (kC) of both Phe and Pyr initially decreased at fast rates and then at more moderate rates later on, resulting from the plasticizing effect of surfactants adsorbed on leaf surfaces. In addition, the photolysis rate constants (kP) decreased with the presence of SDBS but increased with the presence of Brij35. Overall, the total clearance rates of PAHs (kT) adsorbed onto living soybean leaf surfaces were inhibited by the presence of SDBS but promoted by the presence of Brij35. These observations show that surfactants may significantly alter the clearance of PAHs in agricultural systems, and the potential impact of surfactants on crop safety is closely related to surfactant types in natural environments.

  1. An evaluation of lignosulfonate as a sacrificial adsorbate in surfactant flooding

    SciTech Connect

    Hong, S.A.; Bae, J.H.; Lewis, G.R.

    1987-02-01

    A study was conducted to investigate the feasibility of using lignosulfonate as a sacrificial agent in the surfactant flooding process. An analytical technique based on high-performance liquid chromatography (HPLC) analysis was used to determine the concentration of lignosulfonate and petroleum sulfonate. Lignosulfonate and petroleum sulfonate adsorption isotherms were established and used to assess the sacrificial effect of lignosulfonate. A simple model to describe the ion exchange in the presence of lignosulfonate was developed. This model includes the association of cations with lignosulfonate. The main results of this study are as follows. First, surfactant loss can be reduced significantly (> 50% reduction) by pretreatment with a lignosulfonate preflush. However, no significant reduction is obtained when lignosulfonate is incorporated with the surfactant slug. Second, more cations are exchanged from the rock in the presence of lignosulfonate. This enhanced cation exchange is a result of the association of divalent cations with lignosulfonate. Third, lingosulfonate causes dissolution of soluble minerals to a much greater extent than brine or petroleum sulfonate, producing undesirable bivalent cations. Finally, the brine tolerance and optimal salinity of petroleum sulfonate are not greatly affected by lignosulfonate. From these laboratory results, we conclude that lignosulfonate has potential as a sacrificial adsorbate for surfactant flooding.

  2. An evaluation of lignosulfonate as a sacrificial adsorbate in surfactant flooding

    SciTech Connect

    Hong, S.A.; Bae, J.H.; Lewis, G.R.

    1984-04-01

    A study was conducted to investigate the feasibility of using lignosulfonate as a sacrificial agent in the surfactant flooding process. An analytical technique based on HPLC analysis was used to determine the concentration of lignosulfonate and petroleum sulfonate. Lignosulfonate and petroleum sulfonate adsorption isotherms were established and used to assess the sacrificial effect of lignosulfonate. A simple model to describe the ion exchange in the presence of lignosulfonate was developed. This model includes the association of cations with lignosulfonate. The main results of this study are as follows. First, surfactant loss can be reduced significantly > 50% reduction) by pretreatment with a lignosulfonate preflush. However, no significant reduction is obtained when lignosulfonate is incorporated with the surfactant slug. Second, more cations are exchanged from the rock in the presence of lignosulfonate. This enchanced cation-exchange is due to the association of divalent cations with lignosulfonate. Third, lignosulfonate causes dissolution of soluble minerals to a much greater extent than brine or petroleum sulfonate, producing undesirable divalent cations. Finally, the brine tolerance and optimal salinity of petroleum sulfonate are not greatly affected by lignosulfonate. Based on these laboratory results, we conclude that lignosulfonate has potential as a sacrificial adsorbate for surfactant flooding.

  3. Sequential adsorption of an irreversibly adsorbed nonionic surfactant and an anionic surfactant at an oil/aqueous interface.

    PubMed

    Kirby, Stephanie M; Anna, Shelley L; Walker, Lynn M

    2015-04-14

    Aerosol-OT (AOT) and Tween 80 are two of the main surfactants in commercial dispersants used in response to oil spills. Understanding how multicomponent surfactant systems interact at oil/aqueous interfaces is crucial for improving both dispersant design and application efficacy. This is true of many multicomponent formulations; a lack of understanding of competition for the oil/water interface hinders formulation optimization. In this study, we have characterized the sequential adsorption behavior of AOT on squalane/aqueous interfaces that have been precoated with Tween 80. A microtensiometer is used to measure the dynamic interfacial tension of the system. Tween 80 either partially or completely irreversibly adsorbs to squalane/aqueous interfaces when rinsed with deionized water. These Tween 80 coated interfaces are then exposed to AOT. AOT adsorption increases with AOT concentration for all Tween 80 coverages, and the resulting steady-state interfacial tension values are interpreted using a Langmuir isotherm model. In the presence of 0.5 M NaCl, AOT adsorption significantly increases due to counterion charge screening of the negatively charged head groups. The presence of Tween 80 on the interface inhibits AOT adsorption, reducing the maximum surface coverage as compared to a clean interface. Tween 80 persists on the interface even after exposure to high concentrations of AOT.

  4. Sequential adsorption of an irreversibly adsorbed nonionic surfactant and an anionic surfactant at an oil/aqueous interface.

    PubMed

    Kirby, Stephanie M; Anna, Shelley L; Walker, Lynn M

    2015-04-14

    Aerosol-OT (AOT) and Tween 80 are two of the main surfactants in commercial dispersants used in response to oil spills. Understanding how multicomponent surfactant systems interact at oil/aqueous interfaces is crucial for improving both dispersant design and application efficacy. This is true of many multicomponent formulations; a lack of understanding of competition for the oil/water interface hinders formulation optimization. In this study, we have characterized the sequential adsorption behavior of AOT on squalane/aqueous interfaces that have been precoated with Tween 80. A microtensiometer is used to measure the dynamic interfacial tension of the system. Tween 80 either partially or completely irreversibly adsorbs to squalane/aqueous interfaces when rinsed with deionized water. These Tween 80 coated interfaces are then exposed to AOT. AOT adsorption increases with AOT concentration for all Tween 80 coverages, and the resulting steady-state interfacial tension values are interpreted using a Langmuir isotherm model. In the presence of 0.5 M NaCl, AOT adsorption significantly increases due to counterion charge screening of the negatively charged head groups. The presence of Tween 80 on the interface inhibits AOT adsorption, reducing the maximum surface coverage as compared to a clean interface. Tween 80 persists on the interface even after exposure to high concentrations of AOT. PMID:25798716

  5. Long-wave Marangoni convection in a heated liquid layer with insoluble surfactant

    NASA Astrophysics Data System (ADS)

    Morozov, Matvey; Oron, Alex; Nepomnyashchy, Alexander

    2013-11-01

    Recently, long-wave Marangoni convection in a heated binary-liquid layer was considered by Podolny et al. (Phys. Fluids 18, 054104, 2006) revealing rich dynamics stemming from oscillatory instability. These results were obtained in the absence of surfactants. In the present work we investigate an opposite limit: a liquid layer with insoluble surfactant. We consider a liquid layer lying on a solid horizontal substrate with insoluble surfactant adsorbed at the deformable free surface. Convection is triggered by a given transverse temperature gradient. Long-wave linear stability analysis of the quiescent state of the layer reveals a competition between monotonic and oscillatory modes of instability. We derive nonlinear evolution equations governing the large-scale dynamics of the layer. Linear stability analysis of these equations indicates their applicability only in the case of oscillatory instability. We then carry out weakly nonlinear analysis in the vicinity of the oscillatory-instability threshold for the case of a 2D layer, and study corresponding pattern selection. Finally, we compare the analytical results with the numerical solutions of our nonlinear evolution equations. This work is supported by the European Union via FP7 Marie Curie scheme Grant PITN-GA-2008-214919 (MULTIFLOW).

  6. Dynamics in Adsorbed Homopolymer Layers: Entanglements and Osmotic Effects

    NASA Astrophysics Data System (ADS)

    Santore, Maria; Mubarekyan, Ervin

    2001-03-01

    This work seeks the dynamic mechanism for the exchange of homopolymer chains between a dilute solution and a layer adsorbed at the solid-liquid interface. With the model system of polyethylene oxide (PEO) adsorbed onto silica from aqueous solution, it is shown that the behavior of saturated interfaces compared to starved layers reveals an interesting trend: The characteristic self exchange time is dependent only on coverage, not molecular weight, for chains of 100K or less. Therefore, it is concluded that classical entanglements do not play a role below 100K. For all molecular weights, when the coverage of 0.2 mg/m2 is exceeded, the interfacial dynamics become slow. At lower coverages, chains lie flat in train, with no loops or tails, and no lateral interactions either. The onset of slow dynamics at higher coverages may be a result of both surface crowding and the resistance of loops and tails to new chains approaching the layer.

  7. Transient convective structures in a cooled water layer in the presence of a drift flow and a surfactant

    NASA Astrophysics Data System (ADS)

    Reutov, V. P.; Rybushkina, G. V.

    2016-02-01

    The paper is concerned with three-dimensional convective structures arising in a water layer cooled from above and covered by an adsorbed insoluble surfactant. The water is subjected to a laminar drift flow produced by tangential stresses on a free surface. The surface diffusion of the surfactant are taken into account within the approximation of a nondeformable flat surface. After appropriate reformulation of standard equations governing gravity-capillary convection and surfactant concentration, the problem is solved numerically using a pseudospectral method employed in our previous work. Development of the convective structures with increasing Reynolds number, surfactant film elasticity, and layer thickness is studied. The minimal layer thickness is chosen taking into account the results of relevant laboratory experiments. The cell-to-roll transition is revealed in the thin layer with increasing Reynolds number. The role of dissipation due to the surfactant film is elucidated by comparison with purely gravitational convection. The turbulent convection arising in a thicker layer subjected to a laminar shear flow is examined. Disordered streets containing elongated cells and swirl-like motions are revealed. Images of the surface temperature and the perturbed surfactant concentration are compared.

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

    PubMed

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

    2012-04-26

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

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

    PubMed

    Dan, Abhijit; Gochev, Georgi; Miller, Reinhard

    2015-07-01

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

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

    PubMed

    Dan, Abhijit; Gochev, Georgi; Miller, Reinhard

    2015-07-01

    Oscillating drop tensiometry was applied to study adsorbed interfacial layers at water/air and water/hexane interfaces formed from mixed solutions of β-lactoglobulin (BLG, 1 μM in 10 mM buffer, pH 7 - negative net charge) and the anionic surfactant SDS or the cationic DoTAB. The interfacial pressure Π and the dilational viscoelasticity modulus |E| of the mixed layers were measured for mixtures of varying surfactant concentrations. The double capillary technique was employed which enables exchange of the protein solution in the drop bulk by surfactant solution (sequential adsorption) or by pure buffer (washing out). The first protocol allows probing the influence of the surfactant on a pre-adsorbed protein layer thus studying the protein/surfactant interactions at the interface. The second protocol gives access to the residual values of Π and |E| measured after the washing out procedure thus bringing information about the process of protein desorption. The DoTAB/BLG complexes exhibit higher surface activity and higher resistance to desorption in comparison with those for the SDS/BLG complexes due to hydrophobization via electrostatic binding of surfactant molecules. The neutral DoTAB/BLG complexes achieve maximum elastic response of the mixed layer. Mixed BLG/surfactant layers at the water/oil interface are found to reach higher surface pressure and lower maximum dilational elasticity than those at the water/air surface. The sequential adsorption mode experiments and the desorption study reveal that binding of DoTAB to pre-adsorbed BLG globules is somehow restricted at the water/air surface in comparison with the case of complex formation in the solution bulk and subsequently adsorbed at the water/air surface. Maximum elasticity is achieved with washed out layers obtained after simultaneous adsorption, i.e. isolation of the most surface active DoTAB/BLG complex. These specific effects are much less pronounced at the W/H interface. PMID:25666640

  11. Structure of polymer layers adsorbed from concentrated solutions

    NASA Astrophysics Data System (ADS)

    Auvray, Loïc; Auroy, Philippe; Cruz, Margarida

    1992-06-01

    We study by neutron scattering the interfacial strucuture of poly(dimethylsiloxane) layers irreversibly adsorbed from concentrated solutions or melts. We first measure the thickness h of the layers swollen by a good solvent as a function of the chain polymerisation index N and of the polymer volume fraction in the initial solution Φ. The relation h ≈ N^{0.8}Φ^{0.3}, recently predicted from an analogy between irreversibly adsorbed layers and grafted polymer brushes, describes well our results. We can therefore deduce that there is at least one large loop of about N monomers per adsorbed chain. We also study the shape of the polymer concentration profile in the layers by measuring on two samples the polymer-solid partial structure factor, that is proportional to the Fourier transform of the profile. The model of pseudobrushes predicts a concentration decay varying with the distance of the wall z as z^{-2/5}. This power law profile accounts quantitatively for the angular variation of the polymer-solid cross structure factor but it is difficult to distinguish it without anbiguity from less singular profiles. It implies that the adsorption of PDMS onto silica is sufficiently strong and fast to quench completely the loop distribution in the initial layer. Nous étudions par diffusion de neutrons la structure interfaciale de couches de poly(diméthylsiloxane) irréversiblement adsorbées sur de la silice à partir de solutions semidiluées et de fondus. Nous mesurons d'abord l'épaisseur h des couches gonflées par un bon solvant en fonction du degré de polymérisation des chaînes N et de la fraction volumique dans la solution initiale Φ. La relation h≈ N^{0.8}Φ^{0.3} récemment prédite à partir de l'analogie entre couches irréversiblement adsorbées et brosses de polymères greffés décrit bien nos résultats. Nous en déduisons qu'il existe au moins une grande boucle d'environ N monomères par chaîne adsorbée. Nous étudions aussi la forme du profil de

  12. Evaluation of the Effectiveness of Surfactants and Denaturants to Elute and Denature Adsorbed Protein on Different Surface Chemistries.

    PubMed

    Thyparambil, Aby A; Wei, Yang; Latour, Robert A

    2015-11-01

    The elution and/or denaturation of proteins from material surfaces by chemical excipients such as surfactants and denaturants is important for numerous applications including medical implant reprocessing, bioanalyses, and biodefense. The objective of this study was to develop and apply methods to quantitatively assess how surface chemistry and adsorption conditions influence the effectiveness of three commonly used surfactants (sodium dodecyl sulfate, n-octyl-β-d-glucoside, and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) and two denaturants (guanidium hydrochloride and urea) to elute protein (hen egg white lysozyme and bovine pancreatic ribonuclease A) from three different surface chemistries (silica glass, poly(methyl methacrylate), and high-density polyethylene). The structure and bioactivity of residual protein on the surface following elution were characterized using circular dichroism spectropolarimetry and enzyme assays to assess the extent of protein denaturation. Our results indicate that the denaturants were generally more effective than the surfactants in removing the adsorbed proteins from each type of surface. Also, the denaturing capacity of these excipients on the residual proteins on the surfaces was distinctly different from their influence on the proteins in solution and was unique for each of the adsorption conditions. Taken altogether, these results reveal that the effectiveness of surfactants and denaturants to elute and denature adsorbed protein is significantly influenced by surface chemistry and the conditions from which the protein was adsorbed. These results provide a basis for the selection, design, and further development of chemical agents for protein elution and surface decontamination.

  13. Evaluation of the Effectiveness of Surfactants and Denaturants to Elute and Denature Adsorbed Protein on Different Surface Chemistries.

    PubMed

    Thyparambil, Aby A; Wei, Yang; Latour, Robert A

    2015-11-01

    The elution and/or denaturation of proteins from material surfaces by chemical excipients such as surfactants and denaturants is important for numerous applications including medical implant reprocessing, bioanalyses, and biodefense. The objective of this study was to develop and apply methods to quantitatively assess how surface chemistry and adsorption conditions influence the effectiveness of three commonly used surfactants (sodium dodecyl sulfate, n-octyl-β-d-glucoside, and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) and two denaturants (guanidium hydrochloride and urea) to elute protein (hen egg white lysozyme and bovine pancreatic ribonuclease A) from three different surface chemistries (silica glass, poly(methyl methacrylate), and high-density polyethylene). The structure and bioactivity of residual protein on the surface following elution were characterized using circular dichroism spectropolarimetry and enzyme assays to assess the extent of protein denaturation. Our results indicate that the denaturants were generally more effective than the surfactants in removing the adsorbed proteins from each type of surface. Also, the denaturing capacity of these excipients on the residual proteins on the surfaces was distinctly different from their influence on the proteins in solution and was unique for each of the adsorption conditions. Taken altogether, these results reveal that the effectiveness of surfactants and denaturants to elute and denature adsorbed protein is significantly influenced by surface chemistry and the conditions from which the protein was adsorbed. These results provide a basis for the selection, design, and further development of chemical agents for protein elution and surface decontamination. PMID:26449787

  14. Enhanced CO2 adsorptive performance of PEI/SBA-15 adsorbent using phosphate ester based surfactants as additives.

    PubMed

    Cheng, Dandan; Liu, Yue; Wang, Haiqiang; Weng, Xiaole; Wu, Zhongbiao

    2015-12-01

    In this study, a series of polyetherimide/SBA-15: 2-D hexagonal P6mm, Santa Barbara USA (PEI/SBA-15) adsorbents modified by phosphoric ester based surfactants (including tri(2-ethylhexyl) phosphate (TEP), bis(2-ethylhexyl) phosphate (BEP) and trimethyl phosphonoacetate (TMPA)) were prepared for CO2 adsorption. Experimental results indicated that the addition of TEP and BEP had positive effects on CO2 adsorption capacity over PEI/SBA-15. In particular, the CO2 adsorption amount could be improved by around 20% for 45PEI-5TEP/SBA-15 compared to the additive-free adsorbent. This could be attributed to the decrease of CO2 diffusion resistance in the PEI bulk network due to the interactions between TEP and loaded PEI molecules, which was further confirmed by adsorption kinetics results. In addition, it was also found that the cyclic performance of the TEP-modified adsorbent was better than the surfactant-free one. This could be due to two main reasons, based on the results of in situ DRIFT and TG-DSC tests. First and more importantly, adsorbed CO2 species could be desorbed more rapidly over TEP-modified adsorbent during the thermal desorption process. Furthermore, the enhanced thermal stability after TEP addition ensured lower degradation of amine groups during adsorption/desorption cycles. PMID:26702962

  15. Enhanced CO2 adsorptive performance of PEI/SBA-15 adsorbent using phosphate ester based surfactants as additives.

    PubMed

    Cheng, Dandan; Liu, Yue; Wang, Haiqiang; Weng, Xiaole; Wu, Zhongbiao

    2015-12-01

    In this study, a series of polyetherimide/SBA-15: 2-D hexagonal P6mm, Santa Barbara USA (PEI/SBA-15) adsorbents modified by phosphoric ester based surfactants (including tri(2-ethylhexyl) phosphate (TEP), bis(2-ethylhexyl) phosphate (BEP) and trimethyl phosphonoacetate (TMPA)) were prepared for CO2 adsorption. Experimental results indicated that the addition of TEP and BEP had positive effects on CO2 adsorption capacity over PEI/SBA-15. In particular, the CO2 adsorption amount could be improved by around 20% for 45PEI-5TEP/SBA-15 compared to the additive-free adsorbent. This could be attributed to the decrease of CO2 diffusion resistance in the PEI bulk network due to the interactions between TEP and loaded PEI molecules, which was further confirmed by adsorption kinetics results. In addition, it was also found that the cyclic performance of the TEP-modified adsorbent was better than the surfactant-free one. This could be due to two main reasons, based on the results of in situ DRIFT and TG-DSC tests. First and more importantly, adsorbed CO2 species could be desorbed more rapidly over TEP-modified adsorbent during the thermal desorption process. Furthermore, the enhanced thermal stability after TEP addition ensured lower degradation of amine groups during adsorption/desorption cycles.

  16. Performance of waste activated carbon as a low-cost adsorbent for the removal of anionic surfactant from aquatic environment.

    PubMed

    Gupta, Sandeep; Pal, Anjali; Ghosh, Pranab Kumar; Bandyopadhyay, Manas

    2003-02-01

    In the present study, different low cost adsorbents were screened for their sodium dodecyl sulfate (SDS, an anionic surfactant) removal capacity. Waste activated carbon (WAC) from the aqua purifier has shown high efficiency for SDS removal. The performance evaluation in the presence of various ions (Ca2+, SO4(2-), NO3-, and Cl-) and at various pH was studied. Desorption studies were conducted using simple sonication and pH variation technique. Column adsorption studies were performed. SEM and EDS studies were done on the adsorbing material before adsorption, after adsorption and after desorption of SDS. PMID:12638703

  17. Surfactant-modified montmorillonite as a nanosized adsorbent for removal of an insecticide: kinetic and isotherm studies.

    PubMed

    Hassani, Aydin; Khataee, Alireza; Karaca, Semra; Shirzad-Siboni, Mehdi

    2015-01-01

    Surfactant-modified montmorillonites (MMT) were prepared using trimethyloctylammonium bromide (TMOAB) and employed as a nanosized adsorbent to remove diazinon from aqueous solutions. The prepared adsorbent was characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). The dependence of removal efficiency on initial diazinon concentration, amount of adsorbent, pH of the solution and ionic strength was investigated. The affinity sequence for ion adsorption on TMOAB/MMT was in the order: without anion> sodium carbonate> sodium bicarbonate> sodium sulphate> sodium chloride. The adsorption kinetic and isotherm were best fit by a pseudo-second-order kinetic and Langmuir isotherm models, respectively. PMID:26006742

  18. Adsorbed layers and the origin of Amontons' laws

    NASA Astrophysics Data System (ADS)

    Robbins, Mark

    2000-03-01

    Three hundred years ago, Amontons wrote down phenomenogical friction laws that are still used today. They state that the friction is proportional to load, and independent of the dimensions of the contacting surfaces. The molecular underpinning of these laws has remained unclear. Indeed, exact analytic results and experiments in ultra-high vacuum indicate that the static friction between clean crystalline surfaces almost always vanishes in the thermodynamic limit. Of course any surface exposed to air is typically coated by a thin layer of hydrocarbons, water and other small molecules. Simulations are presented that show that these layers naturally produce static and kinetic friction forces that are consistent with Amontons' laws and other aspects of macroscopic experiments.(G. He, M. H. Muser and M. O. Robbins, Science 284, 1650 (1999).) For example, the friction is only weakly dependent on parameters that are not controlled in most experiments, such as the areal density of adsorbed molecules, their length, the orientation of the surfaces and the direction of sliding. The kinetic friction is of the same order as the static friction and varies only logarithmically with velocity.

  19. The origin and characterization of conformational heterogeneity in adsorbed polymer layers

    NASA Astrophysics Data System (ADS)

    Douglas, Jack F.; Schneider, Hildegard M.; Frantz, Peter; Lipman, Robert; Granick, Steve

    1997-09-01

    The equilibration of polymer conformations tends to be sluggish in polymer layers adsorbed onto highly attractive substrates, so the structure of these layers must be understood in terms of the layer growth process rather than equilibrium theory. Initially adsorbed chains adopt a highly flattened configuration while the chains which arrive later must adapt their configurations to the increasingly limited space available for adsorption. Thus, the chains adsorbed in the late stage of deposition are more tenuously attached to the surface. This type of non-equilibrium growth process is studied for polymethylmethacrylate (PMMA) adsorbed on oxidized silicon where the segmental attraction is strong (0953-8984/9/37/005/img7/segment) and for polystyrene (PS) adsorbed on oxidized silicon from a carbon tetrachloride solution where the segmental attraction is relatively weak (0953-8984/9/37/005/img8/segment). Measurements were based on Fourier transform infrared spectroscopy in attenuated total reflection (FTIR - ATR). In both cases, the chains arriving first adsorbed more tightly, became flattened (as measured by the dichroic ratio), and occupied a disproportionately large fraction of the surface. This non-uniform structure persisted indefinitely for the strongly adsorbed PMMA chains, while the PS chains exhibited a gradual evolution, presumably reflecting an equilibration of the adsorbed layer occurring after long times. On the theoretical side, the initial heterogeneity of these adsorbed polymer layers is modelled using a random sequential adsorption (RSA) model where the size of the adsorbing species is allowed to adapt to the surface space available at the time of adsorption. The inhomogeneity in the size of adsorbing species (hemispheres) in this model is similar to the distribution of chain contacts in our measurements on adsorbed polymer layers. Owing to extensive variance around the mean, conformations having the mean number of chain contacts are least probable, which

  20. Surfactant Modified/Mediated Thin-Layer Chromatographic Systems for the Analysis of Amino Acids

    PubMed Central

    Bhawani, Showkat A.; Albishri, Hassan M.; Mohamad Ibrahim, Mohamad N.; Mohammad, A.

    2013-01-01

    This review incorporates a large number of chromatographic systems modified by the surfactants. A large number of solvent systems and stationary phases are summarized in this paper. Three different kinds of surfactants (anionic, cationic, and nonionic) are used as modifiers for stationary phases as well as solvent systems. Surfactants are used at all the three different concentration levels (below, above, and at critical micelle concentration) where surfactants behave differently. Modifications of both stationary phases and solvent systems by surfactants produced a new generation of chromatographic systems. Microemulsion solvent systems are also incorporated in this paper. Microemulsion thin-layer chromatography is a new approach in the field of chromatography. PMID:24455427

  1. Activity of lactoperoxidase when adsorbed on protein layers.

    PubMed

    Haberska, Karolina; Svensson, Olof; Shleev, Sergey; Lindh, Liselott; Arnebrant, Thomas; Ruzgas, Tautgirdas

    2008-09-15

    Lactoperoxidase (LPO) is an enzyme, which is used as an antimicrobial agent in a number of applications, e.g., food technology. In the majority of applications LPO is added to a homogeneous product phase or immobilised on product surface. In the latter case, however, the measurements of LPO activity are seldom reported. In this paper we have assessed LPO enzymatic activity on bare and protein modified gold surfaces by means of electrochemistry. It was found that LPO rapidly adsorbs to bare gold surfaces resulting in an amount of LPO adsorbed of 2.9mg/m(2). A lower amount of adsorbed LPO is obtained if the gold surface is exposed to bovine serum albumin, bovine or human mucin prior to LPO adsorption. The enzymatic activity of the adsorbed enzyme is in general preserved at the experimental conditions and varies only moderately when comparing bare gold and gold surface pretreated with the selected proteins. The measurement of LPO specific activity, however, indicate that it is about 1.5 times higher if LPO is adsorbed on gold surfaces containing a small amount of preadsorbed mucin in comparison to the LPO directly adsorbed on bare gold.

  2. Effect of alkane chain length and counterion on the freezing transition of cationic surfactant adsorbed film at alkane mixture - water interfaces.

    PubMed

    Tokiwa, Yuhei; Sakamoto, Hiroyasu; Takiue, Takanori; Aratono, Makoto; Matsubara, Hiroki

    2015-05-21

    Penetration of alkane molecules into the adsorbed film gives rise to a surface freezing transition of cationic surfactant at the alkane-water interface. To examine the effect of the alkane chain length and counterion on the surface freezing, we employed interfacial tensiometry and ellipsometry to study the interface of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride aqueous solutions against dodecane, tetradecane, hexadecane, and their mixtures. Applying theoretical equations to the experimental results obtained, we found that the alkane molecules that have the same chain length as the surfactant adsorb preferentially into the surface freezing film. Furthermore, we demonstrated that the freezing transition temperature of cationic surfactant adsorbed film was independent of the kind of counterion. PMID:25932500

  3. Surfactant-modified flowerlike layered double hydroxide-coated magnetic nanoparticles for preconcentration of phthalate esters from environmental water samples.

    PubMed

    Zhao, Xiaoli; Liu, Shuangliu; Wang, Peifang; Tang, Zhi; Niu, Hongyun; Cai, Yaqi; Wu, Fengchang; Wang, Hao; Meng, Wei; Giesy, John P

    2015-10-01

    A novel type of layered, flowerlike magnetic double hydroxide (MLDH) nanoparticles modified by surfactants has been successfully synthesized and was applied as an effective sorbent for pre-concentration of several phthalate ester pollutants (PAEs) from water prior to quantification. The MLDH was obtained via a simple ultrasound-assisted method by using silica coated Fe3O4 as the core and anisotropic Mg-Al layered double hydroxide (Mg-Al LDH) nanocrystals as the shell to which analytes were absorbed. Orientation and dimensionality hierarchical structure as well as the large expandable interlayer free space and positive charge of the Mg-Al LDH shell make it easier to form anionic surfactant micelles on its surface via self-assembly. Due to its high adsorption area, compared with non-mesoporous nano solid-phase extraction agents, mesoporous channel shell and reduction diffusion path, MLDH exhibited high extraction efficiency of organic target residues. Under optimized conditions, with a total of 30mg of adsorbant added to from samples containing 400mL water from the environment recoveries of DPP, DBP, DCP and DOP were consistent with ranges of 69-101%, 79-101%, 86-102% and 63-100%, respectively. Standard deviations of recoveries ranged from 1 to 7%, respectively and the method was sensitive with limits of detection of 12.3, 18.7, 36.5 and 15.6ngL(-1). To the best of our knowledge, this is the first report of use of surfactant-modified MLDH nanoparticles and its application as adsorbent to pre-concentration of PAEs from environmental water samples prior to instrumental analyses.

  4. VERUCLAY – a new type of photo-adsorbent active in the visible light range: modification of montmorillonite surface with organic surfactant

    EPA Science Inventory

    Montmorillonite K10 was treated with VeruSOL-3, a biodegradable and food-grade surfactant mixture of coconut oil, castor oil and citrus extracts, to manufacture a benign catalytic adsorbent that is active in the visible light. Veruclay was characterized by SEM, XRD, TGA, UVDRS, a...

  5. Cellular Responses Modulated by FGF-2 Adsorbed on Albumin/Heparin Layer-by-Layer Assemblies

    PubMed Central

    Kumorek, Marta; Kubies, Dana; Filová, Elena; Houska, Milan; Kasoju, Naresh; Mázl Chánová, Eliška; Matějka, Roman; Krýslová, Markéta; Bačáková, Lucie; Rypáček, František

    2015-01-01

    In a typical cell culture system, growth factors immobilized on the cell culture surfaces can serve as a reservoir of bio-signaling molecules, without the need to supplement them additionally into the culture medium. In this paper, we report on the fabrication of albumin/heparin (Alb/Hep) assemblies for controlled binding of basic fibroblast growth factor (FGF-2). The surfaces were constructed by layer-by-layer adsorption of polyelectrolytes albumin and heparin and were subsequently stabilized by covalent crosslinking with glutaraldehyde. An analysis of the surface morphology by atomic force microscopy showed that two Alb/Hep bilayers are required to cover the surface of substrate. The formation of the Alb/Hep assemblies was monitored by the surface plasmon resonance (SPR), the infrared multiinternal reflection spectroscopy (FTIR MIRS) and UV/VIS spectroscopy. The adsorption of FGF-2 on the cross-linked Alb/Hep was followed by SPR. The results revealed that FGF-2 binds to the Alb/Hep assembly in a dose and time-dependent manner up to the surface concentration of 120 ng/cm2. The bioactivity of the adsorbed FGF-2 was assessed in experiments in vitro, using calf pulmonary arterial endothelial cells (CPAE). CPAE cells could attach and proliferate on Alb/Hep surfaces. The adsorbed FGF-2 was bioactive and stimulated both the proliferation and the differentiation of CPAE cells. The improvement was more pronounced at a lower FGF-2 surface concentration (30 ng/cm2) than on surfaces with a higher concentration of FGF-2 (120 ng/cm2). PMID:25945799

  6. Surfactant-induced nematic wetting layer at a thermotropic liquid crystal/water interface.

    PubMed

    Bahr, Ch

    2006-03-01

    An ellipsometric study of the interface between a thermotropic liquid crystal and water near the nematic-isotropic phase transition of the liquid crystal is presented. At temperatures above the transition, a nematic wetting layer appears at the interface if the water phase contains a surfactant inducing a homeotropic alignment of the nematic phase. The detailed behavior is significantly influenced by the concentration of the surfactant. The results can be described by a Landau model of nematic wetting in which the surfactant concentration tunes the magnitude of an ordering interface potential. PMID:16605490

  7. Surfactant-associated bacteria in the near-surface layer of the ocean

    PubMed Central

    Kurata, Naoko; Vella, Kate; Hamilton, Bryan; Shivji, Mahmood; Soloviev, Alexander; Matt, Silvia; Tartar, Aurélien; Perrie, William

    2016-01-01

    Certain marine bacteria found in the near-surface layer of the ocean are expected to play important roles in the production and decay of surface active materials; however, the details of these processes are still unclear. Here we provide evidence supporting connection between the presence of surfactant-associated bacteria in the near-surface layer of the ocean, slicks on the sea surface, and a distinctive feature in the synthetic aperture radar (SAR) imagery of the sea surface. From DNA analyses of the in situ samples using pyrosequencing technology, we found the highest abundance of surfactant-associated bacterial taxa in the near-surface layer below the slick. Our study suggests that production of surfactants by marine bacteria takes place in the organic-rich areas of the water column. Produced surfactants can then be transported to the sea surface and form slicks when certain physical conditions are met. This finding has potential applications in monitoring organic materials in the water column using remote sensing techniques. Identifying a connection between marine bacteria and production of natural surfactants may provide a better understanding of the global picture of biophysical processes at the boundary between the ocean and atmosphere, air-sea exchange of greenhouse gases, and production of climate-active marine aerosols. PMID:26753514

  8. Surfactant-associated bacteria in the near-surface layer of the ocean.

    PubMed

    Kurata, Naoko; Vella, Kate; Hamilton, Bryan; Shivji, Mahmood; Soloviev, Alexander; Matt, Silvia; Tartar, Aurélien; Perrie, William

    2016-01-01

    Certain marine bacteria found in the near-surface layer of the ocean are expected to play important roles in the production and decay of surface active materials; however, the details of these processes are still unclear. Here we provide evidence supporting connection between the presence of surfactant-associated bacteria in the near-surface layer of the ocean, slicks on the sea surface, and a distinctive feature in the synthetic aperture radar (SAR) imagery of the sea surface. From DNA analyses of the in situ samples using pyrosequencing technology, we found the highest abundance of surfactant-associated bacterial taxa in the near-surface layer below the slick. Our study suggests that production of surfactants by marine bacteria takes place in the organic-rich areas of the water column. Produced surfactants can then be transported to the sea surface and form slicks when certain physical conditions are met. This finding has potential applications in monitoring organic materials in the water column using remote sensing techniques. Identifying a connection between marine bacteria and production of natural surfactants may provide a better understanding of the global picture of biophysical processes at the boundary between the ocean and atmosphere, air-sea exchange of greenhouse gases, and production of climate-active marine aerosols. PMID:26753514

  9. Low-Friction Adsorbed Layers of a Triblock Copolymer Additive in Oil-Based Lubrication.

    PubMed

    Yamada, Shinji; Fujihara, Ami; Yusa, Shin-ichi; Tanabe, Tadao; Kurihara, Kazue

    2015-11-10

    The tribological properties of the dilute solution of an ABA triblock copolymer, poly(11-acrylamidoundecanoic acid)-block-poly(stearyl methacrylate)-block-poly(11-acrylamidoundecanoic acid (A5S992A5), in poly(α-olefin) (PAO) confined between mica surfaces were investigated using the surface forces apparatus (SFA). Friction force was measured as a function of applied load and sliding velocity, and the film thickness and contact geometry during sliding were analyzed using the fringes of equal chromatic order (FECO) in the SFA. The results were contrasted with those of confined PAO films; the effects of the addition of A5S992A5 on the tribological properties were discussed. The thickness of the A5S992A5/PAO system varied with time after surface preparation and with repetitive sliding motions. The thickness was within the range from 40 to 70 nm 1 day after preparation (the Day1 film), and was about 20 nm on the following day (the Day2 film). The thickness of the confined PAO film was thinner than 1.4 nm, indicating that the A5S992A5/PAO system formed thick adsorbed layers on mica surfaces. The friction coefficient was about 0.03 to 0.04 for the Day1 film and well below 0.01 for the Day2 film, which were 1 or 2 orders of magnitude lower than the values for the confined PAO films. The time dependent changes of the adsorbed layer thickness and friction properties should be caused by the relatively low solubility of A5S992A5 in PAO. The detailed analysis of the contact geometry and friction behaviors implies that the particularly low friction of the Day2 film originates from the following factors: (i) shrinkage of the A5S992A5 molecules (mainly the poly(stearyl methacrylate) blocks) that leads to a viscoelastic properties of the adsorbed layers; and (ii) the intervening PAO layer between the adsorbed polymer layers that constitutes a high-fluidity sliding interface. Our results suggest that the block copolymer having relatively low solubility in a lubricant base oil is

  10. Long-wave Marangoni convection in a layer of surfactant solution: Bifurcation analysis

    NASA Astrophysics Data System (ADS)

    Morozov, M.; Oron, A.; Nepomnyashchy, A. A.

    2015-08-01

    We carry out a bifurcation analysis of the deformational mode of oscillatory Marangoni instability emerging in a heated layer of surfactant solution in the presence of the Soret effect and surfactant sorption at the free surface. The analysis is based on a set of long-wave evolution equations derived in our earlier work. By means of weakly nonlinear expansions about the instability threshold, we access the stability of a variety of convective patterns including single traveling and standing waves, superpositions of two traveling and two standing waves, and superpositions of three traveling waves. We have found that stability of convective patterns depends strongly on surfactant sorption; in particular, when adsorption is sufficiently strong the bifurcation is subcritical for any physically feasible value of system parameters.

  11. Nonlinear development of two-layer Couette-Poiseuille flow in the presence of surfactant

    NASA Astrophysics Data System (ADS)

    Bassom, Andrew P.; Blyth, M. G.; Papageorgiou, D. T.

    2010-10-01

    The two-dimensional nonlinear evolution of the interface between two superposed layers of viscous fluid moving in a channel in the presence of an insoluble surfactant is examined. A pair of coupled weakly nonlinear equations is derived describing the interfacial and surfactant dynamics when one of the two fluid layers is very thin in comparison to the other. In contrast to previous work, the dynamics in the thin film are coupled to the dynamics in the thicker layer through a nonlocal integral term. For asymptotically small Reynolds number, the flow in the thicker layer is governed by the Stokes equations. A linearized analysis confirms the linear instability identified by previous workers and it is proven that the film flow is linearly unstable if the undisturbed surfactant concentration exceeds a threshold value. Numerical simulations of the weakly nonlinear equations reveal the existence of finite amplitude traveling-wave solutions. For order one Reynolds number, the flow in the thicker layer is governed by the linearized Navier-Stokes equations. In this case the weakly nonlinear film dynamics are more complex and include the possibility of periodic traveling-waves and chaotic flow.

  12. The role of adsorbed water on the friction of a layer of submicron particles

    USGS Publications Warehouse

    Sammis, Charles G.; Lockner, David A.; Reches, Ze’ev

    2011-01-01

    Anomalously low values of friction observed in layers of submicron particles deformed in simple shear at high slip velocities are explained as the consequence of a one nanometer thick layer of water adsorbed on the particles. The observed transition from normal friction with an apparent coefficient near μ = 0.6 at low slip speeds to a coefficient near μ = 0.3 at higher slip speeds is attributed to competition between the time required to extrude the water layer from between neighboring particles in a force chain and the average lifetime of the chain. At low slip speeds the time required for extrusion is less than the average lifetime of a chain so the particles make contact and lock. As slip speed increases, the average lifetime of a chain decreases until it is less than the extrusion time and the particles in a force chain never come into direct contact. If the adsorbed water layer enables the otherwise rough particles to rotate, the coefficient of friction will drop to μ = 0.3, appropriate for rotating spheres. At the highest slip speeds particle temperatures rise above 100°C, the water layer vaporizes, the particles contact and lock, and the coefficient of friction rises to μ = 0.6. The observed onset of weakening at slip speeds near 0.001 m/s is consistent with the measured viscosity of a 1 nm thick layer of adsorbed water, with a minimum particle radius of approximately 20 nm, and with reasonable assumptions about the distribution of force chains guided by experimental observation. The reduction of friction and the range of velocities over which it occurs decrease with increasing normal stress, as predicted by the model. Moreover, the analysis predicts that this high-speed weakening mechanism should operate only for particles with radii smaller than approximately 1 μm. For larger particles the slip speed required for weakening is so large that frictional heating will evaporate the adsorbed water and weakening will not occur.

  13. Fabrication of Micro-Lens Array using a Chemically Adsorbed Monomolecular Layer

    NASA Astrophysics Data System (ADS)

    Okada, Kazushi; Oohira, Fumikazu; Hosogi, Maho; Hashiguchi, Gen; Mihara, Yutaka; Ogawa, Kazufumi; Shiwaku, Kazuya

    We proposed a new method of patterning a chemically adsorbed monomolecular layer on the substrate and then dropping UV cure material to form a lens shape using oil repellent effect of this film. The curvature radius of the lens was controlled by the amount of the dropped UV cure material. Using this method, a micro-lens array of various radiuses was fabricated. The formed micro-lens array shapes are transferred by the electro-plating and then the micro dies are fabricated, which are used for molding the plastic lens array. The optical characteristic of the molded micro-lens was evaluated.

  14. Adsorbate-catalyzed layer-by-layer metal dissolution in inert electrolyte: Pd(100)-c(2 × 2)-I

    NASA Astrophysics Data System (ADS)

    Schimpf, Jane A.; Abreu, Juan B.; Carrasquillo, Arnaldo; Soriaga, Manuel P.

    1994-08-01

    Studies on the corrosion of Pd in inert ( halide-free) H 2SO 4 solution, catalyzed by a single adsorbed layer of iodine, have been extended to a Pd(100) single-crystal electrode that contained an ordered c(2 × 2) adlattice of iodine. Experimental measurements were based upon a combination of linear-sweep voltammetry, potential-step coulometry, low-energy electron diffraction, and Auger electron spectroscopy. As was earlier noted with polycrystalline electrodes, Pd dissolution occurred only when iodine was present on the surface. More significantly, neither the coverage nor the ordered structure of the iodine adlattice was affected by the dissolution process. These observations strongly suggest that the iodine-catalyzed corrosion occurs one layer at a time.

  15. Effect of the interplay between protein and surface on the properties of adsorbed protein layers.

    PubMed

    Ouberai, Myriam M; Xu, Kairuo; Welland, Mark E

    2014-08-01

    Although protein adsorption to surface is a common phenomenon, investigation of the process is challenging due to the complexity of the interplay between external factors, protein and surface properties. Therefore experimental approaches have to measure the properties of adsorbed protein layers with high accuracy in order to achieve a comprehensive description of the process. To this end, we used a combination of two biosensing techniques, dual polarization interferometry and quartz crystal microbalance with dissipation. From this, we are able to extract surface coverage values, layer structural parameters, water content and viscoelastic properties to examine the properties of protein layers formed at the liquid/solid interface. Layer parameters were examined upon adsorption of proteins of varying size and structural properties, on surfaces with opposite polarity. We show that "soft" proteins such as unfolded α-synuclein and high molecular weight albumin are highly influenced by the surface polarity, as they form a highly diffuse and hydrated layer on the hydrophilic silica surface as opposed to the denser, less hydrated layer formed on a hydrophobic methylated surface. These layer properties are a result of different orientations and packing of the proteins. By contrast, lysozyme is barely influenced by the surface polarity due to its intrinsic structural stability. Interestingly, we show that for a similar molecular weight, the unfolded α-synuclein forms a layer with the highest percentage of solvation not related to surface coverage but resulting from the highest water content trapped within the protein. Together, these data reveal a trend in layer properties highlighting the importance of the interplay between protein and surface for the design of biomaterials. PMID:24780165

  16. Layered double hydroxide-based nanomaterials as highly efficient catalysts and adsorbents.

    PubMed

    Li, Changming; Wei, Min; Evans, David G; Duan, Xue

    2014-11-01

    Layered double hydroxides (LDHs) are a class of anion clays consisting of brucite-like host layers and interlayer anions, which have attracted increasing interest in the fields of catalysis/adsorption. By virtue of the versatility in composition, morphology, and architecture of LDH materials, as well as their unique structural properties (intercalation, topological transformation, and self-assembly with other functional materials), LDHs display great potential in the design and fabrication of nanomaterials applied in photocatalysis, heterogeneous catalysis, and adsorption/separation processes. Taking advantage of the structural merits and various control synthesis strategies of LDHs, the active center structure (e.g., crystal facets, defects, geometric and electronic states, etc.) and macro-nano morphology can be facilely manipulated for specific catalytic/adsorbent processes with largely enhanced performances. In this review, the latest advancements in the design and preparation of LDH-based functional nanomaterials for sustainable development in catalysis and adsorption are summarized.

  17. Method for Controlling Electrical Properties of Single-Layer Graphene Nanoribbons via Adsorbed Planar Molecular Nanoparticles

    NASA Astrophysics Data System (ADS)

    Tanaka, Hirofumi; Arima, Ryo; Fukumori, Minoru; Tanaka, Daisuke; Negishi, Ryota; Kobayashi, Yoshihiro; Kasai, Seiya; Yamada, Toyo Kazu; Ogawa, Takuji

    2015-07-01

    A simple method for fabricating single-layer graphene nanoribbons (sGNRs) from double-walled carbon nanotubes (DWNTs) was developed. A sonication treatment was employed to unzip the DWNTs by inducing defects in them through annealing at 500 °C. The unzipped DWNTs yielded double-layered GNRs (dGNRs). Further sonication allowed each dGNR to be unpeeled into two sGNRs. Purification performed using a high-speed centrifuge ensured that more than 99% of the formed GNRs were sGNRs. The changes induced in the electrical properties of the obtained sGNR by the absorption of nanoparticles of planar molecule, naphthalenediimide (NDI), were investigated. The shape of the I-V curve of the sGNRs varied with the number of NDI nanoparticles adsorbed. This was suggestive of the existence of a band gap at the narrow-necked part near the NDI-adsorbing area of the sGNRs.

  18. Cooperation between adsorbates accounts for the activation of atomic layer deposition reactions.

    PubMed

    Shirazi, Mahdi; Elliott, Simon D

    2015-04-14

    Atomic layer deposition (ALD) is a technique for producing conformal layers of nanometre-scale thickness, used commercially in non-planar electronics and increasingly in other high-tech industries. ALD depends on self-limiting surface chemistry but the mechanistic reasons for this are not understood in detail. Here we demonstrate, by first-principle calculations of growth of HfO2 from Hf(N(CH3)2)4-H2O and HfCl4-H2O and growth of Al2O3 from Al(CH3)3-H2O, that, for all these precursors, co-adsorption plays an important role in ALD. By this we mean that previously-inert adsorbed fragments can become reactive once sufficient numbers of molecules adsorb in their neighbourhood during either precursor pulse. Through the calculated activation energies, this 'cooperative' mechanism is shown to have a profound influence on proton transfer and ligand desorption, which are crucial steps in the ALD cycle. Depletion of reactive species and increasing coordination cause these reactions to self-limit during one precursor pulse, but to be re-activated via the cooperative effect in the next pulse. This explains the self-limiting nature of ALD.

  19. Method for Controlling Electrical Properties of Single-Layer Graphene Nanoribbons via Adsorbed Planar Molecular Nanoparticles

    PubMed Central

    Tanaka, Hirofumi; Arima, Ryo; Fukumori, Minoru; Tanaka, Daisuke; Negishi, Ryota; Kobayashi, Yoshihiro; Kasai, Seiya; Yamada, Toyo Kazu; Ogawa, Takuji

    2015-01-01

    A simple method for fabricating single-layer graphene nanoribbons (sGNRs) from double-walled carbon nanotubes (DWNTs) was developed. A sonication treatment was employed to unzip the DWNTs by inducing defects in them through annealing at 500 °C. The unzipped DWNTs yielded double-layered GNRs (dGNRs). Further sonication allowed each dGNR to be unpeeled into two sGNRs. Purification performed using a high-speed centrifuge ensured that more than 99% of the formed GNRs were sGNRs. The changes induced in the electrical properties of the obtained sGNR by the absorption of nanoparticles of planar molecule, naphthalenediimide (NDI), were investigated. The shape of the I-V curve of the sGNRs varied with the number of NDI nanoparticles adsorbed. This was suggestive of the existence of a band gap at the narrow-necked part near the NDI-adsorbing area of the sGNRs. PMID:26205209

  20. Method for Controlling Electrical Properties of Single-Layer Graphene Nanoribbons via Adsorbed Planar Molecular Nanoparticles.

    PubMed

    Tanaka, Hirofumi; Arima, Ryo; Fukumori, Minoru; Tanaka, Daisuke; Negishi, Ryota; Kobayashi, Yoshihiro; Kasai, Seiya; Yamada, Toyo Kazu; Ogawa, Takuji

    2015-01-01

    A simple method for fabricating single-layer graphene nanoribbons (sGNRs) from double-walled carbon nanotubes (DWNTs) was developed. A sonication treatment was employed to unzip the DWNTs by inducing defects in them through annealing at 500 °C. The unzipped DWNTs yielded double-layered GNRs (dGNRs). Further sonication allowed each dGNR to be unpeeled into two sGNRs. Purification performed using a high-speed centrifuge ensured that more than 99% of the formed GNRs were sGNRs. The changes induced in the electrical properties of the obtained sGNR by the absorption of nanoparticles of planar molecule, naphthalenediimide (NDI), were investigated. The shape of the I-V curve of the sGNRs varied with the number of NDI nanoparticles adsorbed. This was suggestive of the existence of a band gap at the narrow-necked part near the NDI-adsorbing area of the sGNRs. PMID:26205209

  1. Adsorption of micelle-forming surfactants from aqueous solutions on disperse titanium boride

    SciTech Connect

    Grodskii, A.S.; Komleva, E.A.; Frolov, Yu.G.

    1988-08-10

    Adsorption studies showed that nonionogenic and cationic surfactants are adsorbed on the surface of disperse titanium boride. Anionic surfactants are virtually not adsorbed due to the negative charge of the particles. It was found that in the region of low concentrations of surfactants in the solution, adsorption of Sintanols takes place in lyophobic regions and the surface of the particles becomes hydrophilic. The Sintamid molecules are adsorbed on the entire interface, including both hydrophobic and hydrophilic sections, with subsequent formation of bimolecular layers by adsorption on hydrophobic sections. Catamine-AB is adsorbed on hydrophilic sections of the surface also with the formation of bimolecular layers. Developed polymolecular layers up to 10-15 nm thick are formed on titanium boride particles from micellar solutions of nonionigenic and cationic surfactants.

  2. Methotrexate intercalated layered double hydroxides with the mediation of surfactants: Mechanism exploration and bioassay study.

    PubMed

    Dai, Chao-Fan; Tian, De-Ying; Li, Shu-Ping; Li, Xiao-Dong

    2015-12-01

    Methotrexatum intercalated layered double hydroxides (MTX/LDHs) hybrids were synthesized by the co-precipitation method and three kinds of nonionic surfactants with different hydrocarbon chain lengths were used. The resulting hybrids were then characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). XRD and FTIR investigations manifest the successful intercalation of MTX anions into the interlayer of LDHs. TEM graphs indicate that the morphology of the hybrids changes with the variation of the chain length of the surfactants, i.e., the particles synthesized using polyethylene glycol (PEG-7) present regular disc morphology with good monodispersity, while samples with the mediation of alkyl polyglycoside (APG-14) are heavily aggregated and samples with the addition of polyvinylpyrrolidone (PVP-10) exhibit irregular branches. Furthermore, the release and bioassay experiments show that monodisperse MTX/LDHs present good controlled-release and are more efficient in the suppression of the tumor cells. PMID:26354264

  3. Methotrexate intercalated layered double hydroxides with the mediation of surfactants: Mechanism exploration and bioassay study.

    PubMed

    Dai, Chao-Fan; Tian, De-Ying; Li, Shu-Ping; Li, Xiao-Dong

    2015-12-01

    Methotrexatum intercalated layered double hydroxides (MTX/LDHs) hybrids were synthesized by the co-precipitation method and three kinds of nonionic surfactants with different hydrocarbon chain lengths were used. The resulting hybrids were then characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). XRD and FTIR investigations manifest the successful intercalation of MTX anions into the interlayer of LDHs. TEM graphs indicate that the morphology of the hybrids changes with the variation of the chain length of the surfactants, i.e., the particles synthesized using polyethylene glycol (PEG-7) present regular disc morphology with good monodispersity, while samples with the mediation of alkyl polyglycoside (APG-14) are heavily aggregated and samples with the addition of polyvinylpyrrolidone (PVP-10) exhibit irregular branches. Furthermore, the release and bioassay experiments show that monodisperse MTX/LDHs present good controlled-release and are more efficient in the suppression of the tumor cells.

  4. Path-integral Monte Carlo simulation of the second layer of 4He adsorbed on graphite

    NASA Astrophysics Data System (ADS)

    Pierce, Marlon; Manousakis, Efstratios

    1999-02-01

    We have developed a path-integral Monte Carlo method for simulating helium films and apply it to the second layer of helium adsorbed on graphite. We use helium-helium and helium-graphite interactions that are found from potentials which realistically describe the interatomic interactions. The Monte Carlo sampling is over both particle positions and permutations of particle labels. From the particle configurations and static structure factor calculations, we find that this layer possesses, in order of increasing density, a superfluid liquid phase, a 7×7 commensurate solid phase that is registered with respect to the first layer, and an incommensurate solid phase. By applying the Maxwell construction to the dependence of the low-temperature total energy on the coverage, we are able to identify coexistence regions between the phases. From these, we deduce an effectively zero-temperature phase diagram. Our phase boundaries are in agreement with heat capacity and torsional oscillator measurements, and demonstrate that the experimentally observed disruption of the superfluid phase is caused by the growth of the commensurate phase. We further observe that the superfluid phase has a transition temperature consistent with the two-dimensional value. Promotion to the third layer occurs for densities above 0.212 atom/Å 2, in good agreement with experiment. Finally, we calculate the specific heat for each phase and obtain peaks at temperatures in general agreement with experiment.

  5. REUSABLE ADSORBENTS FOR DILUTE SOLUTIONS SEPARATION. 5: PHOTODEGRADATION OF ORGANIC COMPOUNDS ON SURFACTANT-MODIFIED TITANIA. (R828598C753)

    EPA Science Inventory

    A semiconductor titania (TiO2) surface was modified by surfactant adsorption to make it more hydrophobic and to increase the adsorption of hydrophobic organic compounds (HOCs) and their photodegradation rates under UV irradiation. Photocatalytic experiments using Ti...

  6. Free energy of electrical double layers: Entropy of adsorbed ions and the binding polynomial

    SciTech Connect

    Stigter, D.; Dill, K.A. )

    1989-09-07

    The authors adapt the method of binding polynomials to general problems of binding equilibria of ions to polybases, polyacids, and mixed polyelectrolytes, such as proteins and other colloids. For spherical particles with a smeared charge the interaction effects are taken into account using the Poisson-Boltzmann equation, which is shown to differ little from the Debye-Hueckel approximation under conditions met in most protein solutions. Examples are given of the salt dependence of pH titration equilibria. Binding polynomials produce an extra term in the free energy of the electrical double layer, which arises from the entropy of the adsorbed ions. The maximum term method applied to the binding polynominal yields an expression which is similar to that derived by the charging process of Chan and Mitchell. Applications to monolayers and to polyelectrolyte gels are also discussed.

  7. Ultra-Thin Optically Transparent Carbon Electrodes Produced from Layers of Adsorbed Proteins

    PubMed Central

    Alharthi, Sarah A.; Benavidez, Tomas E.; Garcia, Carlos D.

    2013-01-01

    This work describes a simple, versatile, and inexpensive procedure to prepare optically transparent carbon electrodes, using proteins as precursors. Upon adsorption, the protein-coated substrates were pyrolyzed under reductive conditions (5% H2) to form ultra-thin, conductive electrodes. Because proteins spontaneously adsorb to interfaces forming uniform layers, the proposed method does not require a precise control of the preparation conditions, specialized instrumentation, or expensive precursors. The resulting electrodes were characterized by a combination of electrochemical, optical, and spectroscopic means. As a proof-of-concept, the optically-transparent electrodes were also used as substrate for the development of an electrochemical glucose biosensor. The proposed films represent a convenient alternative to more sophisticated, and less available, carbon-based nanomaterials. Furthermore, these films could be formed on a variety of substrates, without classical limitations of size or shape. PMID:23421732

  8. Characterization of the surface-active components of sugar beet pectin and the hydrodynamic thickness of the adsorbed pectin layer.

    PubMed

    Siew, Chee Kiong; Williams, Peter A; Cui, Steve W; Wang, Qi

    2008-09-10

    The fraction of sugar beet pectin (SBP) adsorbed onto limonene oil droplets during emulsification has been isolated, and its chemical and physicochemical characteristics have been determined. While the SBP sample itself was found to contain 2.67 and 1.06% protein and ferulic acid, respectively, the adsorbed fraction contained 11.10% protein and 2.16% ferulic acid. The adsorbed fraction was also found to have a higher degree of acetylation, notably at the C2 position on the galacturonic acid residues, and was also found to contain a higher proportion of neutral sugars, which are present in the ramified side chains of the pectin molecules. The thickness of the layer of SBP adsorbed onto polystyrene latex particles was studied by dynamic light scattering and was found to increase with increasing surface coverage. It was found to have a value of approximately 140 nm at plateau coverage, which closely corresponded to the hydrodynamic diameter of the pectin chains. The adsorbed layer thickness was found to be sensitive to pH and the presence of electrolyte. The thickness at a surface coverage of approximately 20 mg/m(2) in the absence of electrolyte at pH approximately 4 was 107 nm and at pH 8.8 was 70 nm, while at pH approximately 4 in the presence of 10 mM NaCl the thickness was found to be 70 nm. It was concluded that the SBP molecules form multilayers at the surface due to electrostatic interaction between the positively charged protein moieties and the galacturonic acid residues. The removal of calcium from the SBP had no effect on the adsorbed layer thickness; hence, multilayer formation due to calcium ion cross-linking was considered unlikely.

  9. Measuring sub-nm adsorbed water layer thickness and desorption rate using a fused-silica whispering-gallery microresonator

    NASA Astrophysics Data System (ADS)

    Ganta, D.; Dale, E. B.; Rosenberger, A. T.

    2014-05-01

    We report an optical method for measuring the thickness of the water layer adsorbed onto the surface of a high-Q fused-silica microresonator. Light from a tunable diode laser operating near 1550 nm is coupled into the microresonator to excite whispering-gallery modes (WGMs). By observing thermal distortion or even bistability of the WGM resonances caused by absorption in the water layer, the contribution of that absorption to the total loss is determined. Thereby, the thickness of the water layer is found to be ˜0.1 nm (approximately one monolayer). This method is further extended to measure the desorption rate of the adsorbed water, which is roughly exponential with a decay time of ˜40 h when the fused-silica microresonator is held in a vacuum chamber at low pressure.

  10. Viscoelastic properties of adsorbed and cross-linked polypeptide and protein layers at a solid-liquid interface.

    PubMed

    Dutta, Amit K; Nayak, Arpan; Belfort, Georges

    2008-08-01

    The real-time changes in viscoelasticity of adsorbed poly(L-lysine) (PLL) and adsorbed histone (lysine rich fraction) due to cross-linking by glutaraldehyde and corresponding release of associated water were investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D) and attenuated total reflection Fourier transform infrared spectroscopy (ATR/FTIR). The kinetics of PLL and histone adsorption were measured through changes in mass adsorbed onto a gold-coated quartz surface from changes in frequency and dissipation and using the Voigt viscoelastic model. Prior to cross-linking, the shear viscosity and shear modulus of the adsorbed PLL layer were approximately 3.0 x 10(-3) Pas and approximately 2.5 x 10(5) Pa, respectively, while after cross-linking, they increased to approximately 17.5 x 10(-3) Pas and approximately 2.5 x 10(6) Pa, respectively. For the adsorbed histone layer, shear viscosity and shear modulus increased modestly from approximately 1.3 x 10(-3) to approximately 2.0 x 10(-3) Pas and from approximately 1.2 x 10(4) to approximately 1.6 x 10(4) Pa, respectively. The adsorbed mass estimated from the Sauerbrey equation (perfectly elastic) and the Voigt viscoelastic model differ appreciably prior to cross-linking whereas after cross-linking they converged. This is because trapped water molecules were released during cross-linking. This was confirmed experimentally via ATR/FTIR measurements. The variation in viscoelastic properties increased substantially after cross-linking presumably due to fluctuation of the randomly cross-linked network structure. An increase in fluctuation of the viscoelastic properties and the loss of imbibed water could be used as a signature of the formation of a cross-linked network and the amount of cross-linking, respectively. PMID:18508070

  11. Disruption of viscoelastic beta-lactoglobulin surface layers at the air-water interface by nonionic polymeric surfactants.

    PubMed

    Rippner Blomqvist, B; Ridout, M J; Mackie, A R; Wärnheim, T; Claesson, P M; Wilde, P

    2004-11-01

    Nonequilibrium interfacial layers formed by competitive adsorption of beta-lactoglobulin and the nonionic triblock copolymer PEO99-PPO65-PEO99 (F127) to the air-water interface were investigated in order to explain the influence of polymeric surfactants on protein film surface rheology and foam stability. Surface dilatational and shear rheological methods, surface tension measurements, dynamic thin-film measurements, diffusion measurements (from fluorescence recovery after photo bleaching), and determinations of foam stability were used as methods. The high surface viscoelasticity, both the shear and dilatational, of the protein films was significantly reduced by coadsorption of polymeric surfactant. The drainage rate of single thin films, in the presence of beta-lactoglobulin, increased with the amount of added F127, but equilibrium F127 films were found to be thicker than beta-lactoglobulin films, even at low concentration of the polymeric surfactant. It is concluded that the effect of the nonionic triblock copolymer on the interfacial rheology of beta-lactoglobulin layers is similar to that of low molecular weight surfactants. They differ however in that F127 increases the thickness of thin liquid films. In addition, the significant destabilizing effect of low molecular weight surfactants on protein foams is not found in the investigated system. This is explained as due to long-range steric forces starting to stabilize the foam films at low concentrations of F127. PMID:15518507

  12. Disruption of viscoelastic beta-lactoglobulin surface layers at the air-water interface by nonionic polymeric surfactants.

    PubMed

    Rippner Blomqvist, B; Ridout, M J; Mackie, A R; Wärnheim, T; Claesson, P M; Wilde, P

    2004-11-01

    Nonequilibrium interfacial layers formed by competitive adsorption of beta-lactoglobulin and the nonionic triblock copolymer PEO99-PPO65-PEO99 (F127) to the air-water interface were investigated in order to explain the influence of polymeric surfactants on protein film surface rheology and foam stability. Surface dilatational and shear rheological methods, surface tension measurements, dynamic thin-film measurements, diffusion measurements (from fluorescence recovery after photo bleaching), and determinations of foam stability were used as methods. The high surface viscoelasticity, both the shear and dilatational, of the protein films was significantly reduced by coadsorption of polymeric surfactant. The drainage rate of single thin films, in the presence of beta-lactoglobulin, increased with the amount of added F127, but equilibrium F127 films were found to be thicker than beta-lactoglobulin films, even at low concentration of the polymeric surfactant. It is concluded that the effect of the nonionic triblock copolymer on the interfacial rheology of beta-lactoglobulin layers is similar to that of low molecular weight surfactants. They differ however in that F127 increases the thickness of thin liquid films. In addition, the significant destabilizing effect of low molecular weight surfactants on protein foams is not found in the investigated system. This is explained as due to long-range steric forces starting to stabilize the foam films at low concentrations of F127.

  13. Synthesis of organic rectorite with novel Gemini surfactants for copper removal

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  14. Dilatational rheology of beta-casein adsorbed layers at liquid-fluid interfaces.

    PubMed

    Maldonado-Valderrama, Julia; Fainerman, Valentin B; Galvez-Ruiz, M José; Martín-Rodriguez, Antonio; Cabrerizo-Vílchez, Miguel A; Miller, Reinhard

    2005-09-22

    The rheological behavior of beta-casein adsorption layers formed at the air-water and tetradecane-water interfaces is studied in detail by means of pendant drop tensiometry. First, its adsorption behavior is briefly summarized at both interfaces, experimentally and also theoretically. Subsequently, the experimental dilatational results obtained for a wide range of frequencies are presented for both interfaces. An interesting dependence with the oscillation frequency is observed via the comparative analysis of the interfacial elasticity (storage part) and the interfacial viscosity (loss part) for the two interfaces. The analysis of the interfacial elasticities provides information on the conformational transitions undergone by the protein upon adsorption at both interfaces. The air-water interface shows a complex behavior in which two maxima merge into one as the frequency increases, whereas only a single maximum is found at the tetradecane interface within the range of frequencies studied. This is interpreted in terms of a decisive interaction between the oil and the protein molecules. Furthermore, the analysis of the interfacial viscosities provides information on the relaxation processes occurring at both interfaces. Similarly, substantial differences arise between the gaseous and liquid interfaces and various possible relaxation mechanisms are discussed. Finally, the experimental elasticities obtained for frequencies higher than 0.1 Hz are further analyzed on the basis of a thermodynamic model. Accordingly, the nature of the conformational transition given by the maximum at these frequencies is discussed in terms of different theoretical considerations. The formation of a protein bilayer at the interface or the limited compressibility of the protein in the adsorbed state are regarded as possible explanations of the maximum.

  15. Thermal Transport across Surfactant Layers on Gold Nanorods in Aqueous Solution.

    PubMed

    Wu, Xuewang; Ni, Yuxiang; Zhu, Jie; Burrows, Nathan D; Murphy, Catherine J; Dumitrica, Traian; Wang, Xiaojia

    2016-04-27

    Ultrafast transient absorption experiments and molecular dynamics simulations are utilized to investigate the thermal transport between aqueous solutions and cetyltrimethylammonium bromide (CTAB)- or polyethylene glycol (PEG)-functionalized gold nanorods (GNRs). The transient absorption measurement data are interpreted with a multiscale heat diffusion model, which incorporates the interfacial thermal conductances predicted by molecular dynamics. According to our observations, the effective thermal conductance of the GNR/PEG/water system is higher than that of the GNR/CTAB/water system with a surfactant layer of the same length. We attribute the enhancement of thermal transport to the larger thermal conductance at the GNR/PEG interface as compared with that at the GNR/CTAB interface, in addition to the water penetration into the hydrophilic PEG layer. Our results highlight the role of the GNR/polymer thermal interfaces in designing biological and composite-based heat transfer applications of GNRs, and the importance of multiscale analysis in interpreting transient absorption data in systems consisting of low interfacial thermal conductances.

  16. Adsorption of a polymeric siloxane surfactant on carbon black particles dispersed in mixtures of water with polar organic solvents.

    PubMed

    Lin, Yining; Smith, Thomas W; Alexandridis, Paschalis

    2002-11-01

    The adsorption of a rake-type polymeric siloxane surfactant (polydimethylsiloxane-graft-polyether copolymer) on carbon black (CB) particles dispersed in mixtures of water with polar organic solvents (ethanol, formamide, or glycerol) has been investigated. The adsorption obeys the Langmuir isotherm at low surfactant concentrations (below the critical micelle concentration, CMC). At these conditions, the average surface area occupied by one siloxane surfactant follows the sequence water+glycerol mixture >plain water >water+ethanol mixture. At higher surfactant concentrations in the solution in contact with the particles, a sharp increase in the adsorbed amount is observed. The adsorbed layer thickness has been determined by dynamic light scattering. Below the CMC the adsorbed layer thickness is less than 10 nm. Above the CMC, the adsorbed layer thickness increases to 20-30 nm, a length scale comparable to the diameter of the siloxane surfactant micelles in aqueous solution. This fact, together with SANS data that we have obtained in the absence of added polar organic solvent, indicates that the structure of the adsorbed layer is similar to that of micelles. The findings presented here are relevant to waterborne coatings and ink formulations, where polymeric surfactants are used in conjunction with polar organic solvents.

  17. Surfactant Dynamics: Spreading and Wave Induced Dynamics of a Monolayer

    NASA Astrophysics Data System (ADS)

    Strickland, Stephen Lee

    Material adsorbed to the surface of a fluid - for instance crude oil in the ocean, biological surfactant on ocular or pulmonary mucous, or emulsions - can form a 2-dimensional mono-molecular layer. These materials, called surfactants, can behave like a compressible viscous 2-dimensional fluid, and can generate surface stresses that influence the sub-fluid's bulk flow. Additionally, the sub-fluid's flow can advect the surfactant and generate gradients in the surfactant distribution and thereby generate gradients in the interfacial properties. Due to the difficulty of non-invasive measurements of the spatial distribution of a molecular monolayer at the surface, little is known about the dynamics that couple the surface motion and the evolving density field. In this dissertation, I will present a novel method for measuring the spatiotemporal dynamics of the surfactant surface density through the fluorescence emission of NBD-tagged phosphatidylcholine, a lipid, and we will compare the surfactant dynamics to the dynamics of the surface morphology.With this method, we will consider the inward and outward spreading of a surfactant on a thin fluid film as well as the advection of a surfactant by linear and non-linear gravity-capillary waves. These two types of surfactant coupled fluid flows will allow us to probe well-accepted assumptions about the coupled fluid-surfactant dynamics. In chapter 1, we review the models used for understanding the spreading of a surfactant on a thin fluid film and the motion of surfactant on a linear gravity-capillary wave. In chapter 2, we will present the experimental methods used in this dissertation. In chapter 3, we will study the outward spreading of a localized region of surfactant and show that the spreading of a monolayer is considerably different from the spreading of thicker-layered surfactant. In chapter 4, we will investigate the inward spreading of a surfactant into a circular surfactant-free region and show that hole closure and

  18. Multi-layer graphene oxide alone and in a composite with nanosilica: Preparation and interactions with polar and nonpolar adsorbates

    NASA Astrophysics Data System (ADS)

    Gun'ko, V. M.; Turov, V. V.; Zarko, V. I.; Goncharuk, O. V.; Matkovsky, A. K.; Prykhod'ko, G. P.; Nychiporuk, Yu. M.; Pakhlov, E. M.; Krupska, T. V.; Balakin, D. Yu.; Charmas, B.; Andriyko, L. S.; Skubiszewska-Zięba, J.; Marynin, A. I.; Ukrainets, A. I.; Kartel, M. T.

    2016-11-01

    Freeze-dried multi-layer graphene oxide (MLGO), produced from natural flake graphite using ionic hydration method, demonstrates strong interactions of functionalized carbon sheets with polar or nonpolar adsorbates or co-adsorbates depending on the characteristics of dispersion media. Interactions of MLGO with a mixture of water and n-decane in chloroform media provide specific surface area (Su) in contact with unfrozen liquids greater than 1000 m2/g corresponding to stacks with 3-5 carbon layers. Electrostatic interactions between functionalized carbon sheets in dried MLGO are very strong. Therefore, nonpolar molecules (benzene, decane, nitrogen) cannot penetrate between the sheets. Water molecules can effectively penetrate between the sheets, especially if MLGO is located in weakly polar CDCl3 medium. In this case, n-decane molecules (co-adsorbate) can also penetrate into the sheet stacks and locate around nonpolar fragments of the sheets. The Su value of MLGO being in contact with unfrozen water can reach 360 m2/g, but upon co-adsorption of water with decane Su = 930 m2/g, i.e., hydrophobic interactions of the mentioned fragments with decane are stronger that with co-adsorbed water. Water alone (0.25 or 0.5 g/g) bound to MLGO in a mixture with fumed silica A-300 in air or CDCl3 media can provide Su = 30-50 m2/g. Pores in wetted MLGO or MLGO/A-300 mainly correspond to mesopores. Nanosilica does not provide significant opening of the MLGO sheet stacks during their mechanical mixing.

  19. Cationic surfactant-assisted hydrothermal synthesis of few-layer molybdenum disulfide/graphene composites: Microstructure and electrochemical lithium storage

    NASA Astrophysics Data System (ADS)

    Ma, Lin; Huang, Guochuang; Chen, Weixiang; Wang, Zhen; Ye, Jianbo; Li, Haiyang; Chen, Dongyun; Lee, Jim Yang

    2014-10-01

    Few-layer molybdenum disulfide/graphene (FL-MoS2/GNS) composites are fabricated by a facile hydrothermal route and a post-annealing with the assistance of various cationic surfactants (dodecyltrimethylammonium bromide, DTAB; octyltrimethylammonium bromide, OTAB; and tetrabutylammonium bromide, TBAB), which have different alkyl-chain lengths and stereo configurations. The effects of these cationic surfactants on the microstructures and electrochemical performances of the FL-MoS2/GNS for lithium storage are investigated. It is demonstrated the cationic surfactants show some ability to control the microstructure (layer number) of FL-MoS2 in composites. The electrochemical performances of FL-MoS2/GNS composites for lithium storage are greatly improved compared to the bare MoS2. Especially, FL-MoS2/GNS with ∼6 MoS2 layers prepared with the assistance of OTAB exhibits very high reversible capacity of ∼1200 mAh g-1 with excellent cycle stability and enhanced rate capability. Electrochemical impedance spectrum also confirms that the FL-MoS2/GNS composite electrodes exhibit much lower electron-transfer resistance than the MoS2. The remarkable electrochemical performances of FL-MoS2/GNS composites can be attributed to the synergistic interaction between FL-MoS2 and graphene and their quasi-3D architectures, which promote lithium diffusion, electron transfer and electrolyte access.

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

    PubMed

    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.

  1. Study of surfactant adsorption on colloidal particles

    SciTech Connect

    Cummins, P.G.; Staples, E. ); Penfold, J. )

    1990-05-03

    Surface tension and small-angle neutron scattering have been used to study the nature of surfactant adsorption on silica sols. This paper presents results on the characterization of the ludox silica sol and adsorbed layers of hexaethylene glycol monododecyl ether (C{sub 12}E{sub 6}). Preliminary results are presented that demonstrate the presence of a lower consolute boundary for the composite system.

  2. 2D sandbox experiments of surfactant foams for mobility control and enhanced LNAPL recovery in layered soils

    NASA Astrophysics Data System (ADS)

    Longpré-Girard, Mélanie; Martel, Richard; Robert, Thomas; Lefebvre, René; Lauzon, Jean-Marc

    2016-10-01

    The ability of surfactant foam to enhance mobility control and LNAPL recovery in a heterogeneous porous media was investigated through sandbox experiments with p-xylene used as LNAPL. A layered heterogeneous porous media was represented in a 2D sandbox filled with two layers of coarse and medium silica sand. Based on previous tests, the surfactant solution used was Ammonyx Lo at a concentration of 0.1% (w/w). The sandbox experimental program included tracer tests done under both uncontaminated and contaminated conditions, foam injection under uncontaminated conditions and surfactant solution and foam injection under contaminated conditions. Tracer tests indicated that the permeability contrast between sand layers was increased by LNAPL contamination. Foam injection under uncontaminated conditions presented a S-shaped front that indicated a better mobility control than the piston-shaped front obtained during tracer tests. During foam injection, complete sweep of the sandbox was achieved with 1.8 pore volume (PV) compared to 2.8 PV during tracer injection, thus indicating better mobility control with foam. Pre-flush of the contaminated sandbox with surfactant solution initiated p-xylene mobilization but no free phase was recovered at the effluent. A negligible p-xylene residual saturation was reached following foam injection in the contaminated sandbox. However, mass balance indicated a total recovery of only 48% of the initial p-xylene, thus indicating an underestimation of the recovery by volatilization. Recovery by volatilization was corrected, which gave the following proportions of LNAPL recovery mechanisms: 19% by mobilization, 16% by dissolution and 65% by volatilization. Results show the potential efficiency of foam remediation of LNAPL source zones in heterogeneous porous media. Still, further developments are needed prior to field scale application, which could benefit from in situ foam production that would simplify on-site operations.

  3. Rate of Molecular Transfer of Allyl Alcohol across an AOT Surfactant Layer Using Muon Spin Spectroscopy.

    PubMed

    Jayasooriya, Upali A; Clayden, Nigel J; Steytler, David C; Oganesyan, Vasily S; Peck, Jamie N T; Khasanov, Rustem; Scheuermann, Robert; Stoykov, Alexey

    2016-01-26

    The transfer rate of a probe molecule across the interfacial layer of a water-in-oil (w/o) microemulsion was investigated using a combination of transverse field muon spin rotation (TF-μSR), avoided level crossing muon spin resonance (ALC-μSR), and Monte Carlo simulations. Reverse microemulsions consist of nanometer-sized water droplets dispersed in an apolar solvent separated by a surfactant monolayer. Although the thermodynamic, static model of these systems has been well described, our understanding of their dynamics is currently incomplete. For example, what is the rate of solute transfer between the aqueous and apolar solvents, and how this is influenced by the structure of the interface? With an appropriate choice of system and probe molecule, μSR offers a unique opportunity to directly probe these interfacial transfer dynamics. Here, we have employed a well characterized w/o microemulsion stabilized by bis(2-ethylhexyl) sodium sulfosuccinate (Aerosol OT), with allyl alcohol (CH2═CH-CH2-OH, AA) as the probe. Resonances due to both muoniated radicals, CMuH2-C*H-CH2-OH and C*H2-CHMu-CH2-OH, were observed with the former being the dominant species. All resonances displayed solvent dependence, with those in the microemulsion observed as a single resonance located at intermediate magnetic fields to those present in either of the pure solvents. Observation of a single resonance is strong evidence for interfacial transfer being in the fast exchange limit. Monte Carlo calculations of the ΔM = 0 ALC resonances are consistent with the experimental data, indicating exchange rates greater than 10(9) s(-1), placing the rate of interfacial transfer at the diffusion limit. PMID:26716949

  4. Rate of Molecular Transfer of Allyl Alcohol across an AOT Surfactant Layer Using Muon Spin Spectroscopy.

    PubMed

    Jayasooriya, Upali A; Clayden, Nigel J; Steytler, David C; Oganesyan, Vasily S; Peck, Jamie N T; Khasanov, Rustem; Scheuermann, Robert; Stoykov, Alexey

    2016-01-26

    The transfer rate of a probe molecule across the interfacial layer of a water-in-oil (w/o) microemulsion was investigated using a combination of transverse field muon spin rotation (TF-μSR), avoided level crossing muon spin resonance (ALC-μSR), and Monte Carlo simulations. Reverse microemulsions consist of nanometer-sized water droplets dispersed in an apolar solvent separated by a surfactant monolayer. Although the thermodynamic, static model of these systems has been well described, our understanding of their dynamics is currently incomplete. For example, what is the rate of solute transfer between the aqueous and apolar solvents, and how this is influenced by the structure of the interface? With an appropriate choice of system and probe molecule, μSR offers a unique opportunity to directly probe these interfacial transfer dynamics. Here, we have employed a well characterized w/o microemulsion stabilized by bis(2-ethylhexyl) sodium sulfosuccinate (Aerosol OT), with allyl alcohol (CH2═CH-CH2-OH, AA) as the probe. Resonances due to both muoniated radicals, CMuH2-C*H-CH2-OH and C*H2-CHMu-CH2-OH, were observed with the former being the dominant species. All resonances displayed solvent dependence, with those in the microemulsion observed as a single resonance located at intermediate magnetic fields to those present in either of the pure solvents. Observation of a single resonance is strong evidence for interfacial transfer being in the fast exchange limit. Monte Carlo calculations of the ΔM = 0 ALC resonances are consistent with the experimental data, indicating exchange rates greater than 10(9) s(-1), placing the rate of interfacial transfer at the diffusion limit.

  5. Photoinduced Reconfiguration Cycle in a Molecular Adsorbate Layer Studied by Femtosecond Inner-Shell Photoelectron Spectroscopy

    SciTech Connect

    Dachraoui, H.; Michelswirth, M.; Bartz, P.; Pfeiffer, W.; Heinzmann, U.; Siffalovic, P.; Schaefer, C.; Schnatwinkel, B.; Mattay, J.; Drescher, M.

    2011-03-11

    A time-resolved study of core-level chemical shifts in a monolayer of aromatic molecules reveals complex photoinduced reaction dynamics. The combination of electron spectroscopy for chemical analysis and ultrashort pulse excitation in the extreme ultraviolet allows performing time-correlated 4d-core-level spectroscopy of iodine atoms that probe the local chemical environment in the adsorbate molecule. The selectivity of the method unveils metastable molecular configurations that appear about 50 ps after the excitation and are efficiently quenched back to the ground state.

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

    SciTech Connect

    Casteel, J.

    1996-07-01

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

  7. Subharmonic excitation in amplitude modulation atomic force microscopy in the presence of adsorbed water layers

    SciTech Connect

    Santos, Sergio; Barcons, Victor; Verdaguer, Albert; Chiesa, Matteo

    2011-12-01

    In ambient conditions, nanometric water layers form on hydrophilic surfaces covering them and significantly changing their properties and characteristics. Here we report the excitation of subharmonics in amplitude modulation atomic force microscopy induced by intermittent water contacts. Our simulations show that there are several regimes of operation depending on whether there is perturbation of water layers. Single period orbitals, where subharmonics are never induced, follow only when the tip is either in permanent contact with the water layers or in pure noncontact where the water layers are never perturbed. When the water layers are perturbed subharmonic excitation increases with decreasing oscillation amplitude. We derive an analytical expression which establishes whether water perturbations compromise harmonic motion and show that the predictions are in agreement with numerical simulations. Empirical validation of our interpretation is provided by the observation of a range of values for apparent height of water layers when subharmonic excitation is predicted.

  8. Observation of spin-glass behavior in nickel adsorbed few layer graphene

    SciTech Connect

    Mitra, Sreemanta; Mondal, Oindrila; Banerjee, Sourish; Chakravorty, Dipankar

    2013-01-14

    Nickel-adsorbed graphene was prepared by first synthesizing graphite oxide (GO) by modified Hummers' method and then reducing a solution containing both GO and Ni{sup 2+}. Energy dispersive X-ray spectroscopy analysis showed 31 at. % nickel was present. Magnetization measurements under both dc and ac magnetic fields were carried out in the temperature range 2 K to 300 K. The zero field cooled and field cooled magnetization data showed a pronounced irreversibility at a temperature around 20 K. The analysis of the ac susceptibility data was carried out by both Vogel-Fulcher as well as power law. From dynamic scaling analysis, the microscopic flipping time {tau}{sub 0}{approx}10{sup -13}s and critical exponent z{nu}=5.9{+-}0.1 were found, indicating the presence of conventional spin glass in the system. The spin glass transition temperature was estimated as 19.5 K. Decay of thermoremanent magnetization was explained by stretched exponential function with a value of the exponent as 0.6. From the results, it is concluded that nickel adsorbed graphene behaves like a spin-glass.

  9. X-ray Reflectivity Studies of Adsorbed Proteins on Langmuir Layers

    NASA Astrophysics Data System (ADS)

    Málková, Šárka; Pingali, Sai V.; Long, Fei; Cho, Wonhwa; Schlossman, Mark L.

    2002-03-01

    Synchrotron X-ray reflectivity is used to study the interaction of the C2 domain of cytosolic phospholipase A2 (cPLA_2-C2) with a phospholipid membrane. SOPC (1-steraoyl-2-oleoyl-sn-glycero-3-phosphocholine) monolayer has been chosen as our model membrane. SOPC monolayer is supported on a buffered, Ca^2+ containing aqueous solution. The original phospholipid layer, which can be described by a two layer model roughened by capillary wave theory, is modified and a three layer model is necessary to fit the data after the protein is injected. The data analysis indicates that a third layer attached to the phospholipid headgroup region is formed. This additional layer corresponds to proteins bound to the phospholipid. The mechanism of the protein binding to the lipid depends on the initial lipid pressure with adsorption being less pronounced at higher pressures. Two control experiments are performed. Buffer containing no Ca^2+ is used in the first and F35/L39A mutant of cPLA_2-C2 (the mutation is in the region containing ligands for multiple Ca^2+ ions) is used in the second. Reflectivity curves do not show any evidence of protein adsorption to the phospholipid monolayer in any of our two control experiments. Our results thus support the idea that the initial pressure of the lipid, Ca^2+ ions and Ca^2+ binding sites of cPLA_2-C2 are important factors for the membrane binding of this protein.

  10. Bionanocomposites based on layered silicates and cationic starch as eco-friendly adsorbents for hexavalent chromium removal.

    PubMed

    Koriche, Yamina; Darder, Margarita; Aranda, Pilar; Semsari, Saida; Ruiz-Hitzky, Eduardo

    2014-07-21

    Functional bionanocomposites based on two layered silicates, the commercial montmorillonite known as Cloisite®Na and a natural bentonite from Algeria, were prepared by intercalation of cationic starch, synthesized with two different degrees of substitution, 0.85 and 0.55. After characterization of the prepared bionanocomposites by XRD and zeta potential measurements, batch studies were conducted to evaluate the adsorption capacity of hexavalent chromium anions from aqueous solution. The adsorption isotherms, adsorption kinetics, and the effect of pH on the process were studied. The removal efficiency was evaluated in the presence of competing anions such as NO3(-), ClO4(-), SO4(2-) and Cl(-). In order to regenerate the adsorbent for its repeated use, the regeneration process was studied in two different extractant solutions, 0.1 M NaCl at pH 10 and 0.28 M Na2CO3 at pH 12. PMID:24658793

  11. Immobilization of DNA at Glassy Ccarbon Electrodes: A Critical Study of Adsorbed Layer

    PubMed Central

    Pedano, M. L.; Rivas, G. A.

    2005-01-01

    In this work we present a critical study of the nucleic acid layer immobilized at glassy carbon electrodes. Different studies were performed in order to assess the nature of the interaction between DNA and the electrode surface. The adsorption and electrooxidation of DNA demonstrated to be highly dependent on the surface and nature of the glassy carbon electrode. The DNA layer immobilized at a freshly polished glassy carbon electrode was very stable even after applying highly negative potentials. The electron transfer of potassium ferricyanide, catechol and dopamine at glassy carbon surfaces modified with thin (obtained by adsorption under controlled potential conditions) and thick (obtained by casting the glassy carbon surface with highly concentrated DNA solutions) DNA layers was slower than that at the bare glassy carbon electrode, although this effect was dependent on the thickness of the layer and was not charge selective. Raman experiments showed an important decrease of the vibrational modes assigned to the nucleobases residues, suggesting a strong interaction of these residues with the electrode surface. The hybridization of oligo(dG)21 and oligo(dC)21 was evaluated from the guanine oxidation signal and the reduction of the redox indicator Co(phen)33+. In both cases the chronopotentiometric response indicated that the compromise of the bases in the interaction of DNA with the electrode surface is too strong, preventing further hybridization. In summary, glassy carbon is a useful electrode material to detect DNA in a direct and very sensitive way, but not to be used for the preparation of biorecognition layers by direct adsorption of the probe sequence on the electrode surface for detecting the hybridization event.

  12. Influence of carboxylic ion-pairing reagents on retention of peptides in thin-layer chromatography systems with C18 silica-based adsorbents.

    PubMed

    Gwarda, Radosław Ł; Aletańska-Kozak, Monika; Klimek-Turek, Anna; Ziajko-Jankowska, Agnieszka; Matosiuk, Dariusz; Dzido, Tadeusz H

    2016-04-01

    One of the main problems related to chromatography of peptides concerns adverse interactions of their strong basic groups with free silanol groups of the silica based stationary phase. Influence of type and concentration of ion-pairing regents on peptide retention in reversed-phase high-performance liquid chromatography (RP-HPLC) systems has been discussed before. Here we present influence of these mobile phase additives on retention of some peptide standards in high-performance thin-layer chromatography (HPTLC) systems with C18 silica-based adsorbents. We prove, that due to different characteristic of adsorbents used in both techniques (RP HPLC and HPTLC), influence of ion-pairing reagents on retention of basic and/or amphoteric compounds also may be quite different. C18 silica-based HPTLC adsorbents provide more complex mechanism of retention and should be rather considered as mixed-mode adsorbents.

  13. Layer structured graphite oxide as a novel adsorbent for humic acid removal from aqueous solution.

    PubMed

    Hartono, Tri; Wang, Shaobin; Ma, Qing; Zhu, Zhonghua

    2009-05-01

    Layer structured graphite oxide (GO) was prepared from graphite using the Hummers-Offeman method, characterised using N(2) adsorption, XRD, XPS, SEM(TEM), and FT-IR, and tested for humic acid (HA) adsorption in aqueous solution. XRD, XPS, and FT-IR measurements indicate the formation of layered structure with strong functional groups of GO. It is also found that the GO exhibits strong and much higher adsorption capacity of HA than graphite. The maximum adsorption capacity of the GO from the Langmuir isotherm is 190 mg/g, higher than activated carbon. For the adsorption, several parameters will affect the adsorption such as solid loading and pH. HA adsorption will decrease with increasing pH and an optimum GO loading is required for maximum adsorption. PMID:19233379

  14. A comparison of didodecyldimethylammonium bromide adsorbed at mica/water and silica/water interfaces using neutron reflection.

    PubMed

    Griffin, Lucy R; Browning, Kathryn L; Truscott, Chris L; Clifton, Luke A; Webster, John; Clarke, Stuart M

    2016-09-15

    The layer structure of the dichain alkyl ammonium surfactant, didodecyldimethylammonium bromide (DDAB), adsorbed from water on to silica and mica surfaces has been determined using neutron reflection. Although sometimes considered interchangeable surfaces for study, we present evidence of significant differences in the adsorbed layer structure below the critical micelle concentration. A complete DDAB bilayer was assembled at the water/mica interface at concentrations below the critical micelle concentration (CMC). In contrast it is not until the CMC was reached that the complete bilayer structure formed on the oxidised silicon crystal. Removal of the complete bilayer on both surfaces was attempted by both washing and ion exchange yet the adsorbed structure proved tenacious.

  15. Extended triple layer modeling of arsenate and phosphate adsorption on a goethite-based granular porous adsorbent.

    PubMed

    Kanematsu, Masakazu; Young, Thomas M; Fukushi, Keisuke; Green, Peter G; Darby, Jeannie L

    2010-05-01

    The extended triple layer model (ETLM), which is consistent with spectroscopic and theoretical molecular evidence, is first systematically tested for its capability to model adsorption of arsenate and phosphate, a strong competitor, on a common goethite-based granular porous adsorptive media (Bayoxide E33 (E33)) in water treatment systems under a wide range of solution conditions. Deprotonated bidentate-binuclear, protonated bidentate-binuclear, and deprotonated monodentate complexes are chosen as surface species for both arsenate and phosphate. The estimated values of the ETLM parameters of arsenate for the adsorbent are close to those for pure goethite minerals previously determined by others. The ETLM predictions for arsenate and phosphate adsorption basically agree with experimental results over a wide range of pH, surface coverage, and solid concentrations. High background electrolyte concentration (i.e., I = 0.1 M), however, was found to strongly impact arsenate and phosphate adsorption on E33 probably because of the porous structure of the adsorbent, which cannot be observed for pure goethite minerals and could not be completely modeled by the ETLM. Prediction of phosphate adsorption isotherms at higher pH were relatively poor, and this may suggest searching for alternative surface species for phosphate. Since adsorption equilibrium constants of major coexisting ions encountered in water treatment systems for goethite minerals have been estimated by others, the application of ETLM theory to this common goethite-based adsorptive media will enable us to understand how those coexisting ions macroscopically and thermodynamically interact with arsenate and phosphate in the environment of adsorptive water treatment system in a way consistent with molecular and spectroscopic evidence.

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

    PubMed

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

    2012-03-15

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

  17. Speciation of trace metals in natural waters: the influence of an adsorbed layer of natural organic matter (NOM) on voltammetric behaviour of copper.

    PubMed

    Louis, Yoann; Cmuk, Petra; Omanović, Dario; Garnier, Cédric; Lenoble, Véronique; Mounier, Stéphane; Pizeta, Ivanka

    2008-01-01

    The influence of an adsorbed layer of the natural organic matter (NOM) on voltammetric behaviour of copper on a mercury drop electrode in natural water samples was studied. The adsorption of NOM strongly affects the differential pulse anodic stripping voltammogram (DPASV) of copper, leading to its distortion. Phase sensitive ac voltammetry confirmed that desorption of adsorbed NOM occurs in general at accumulation potentials more negative than -1.4V. Accordingly, an application of negative potential (-1.6V) for a very short time at the end of the accumulation time (1% of total accumulation time) to remove the adsorbed NOM was introduced in the measuring procedure. Using this protocol, a well-resolved peak without interferences was obtained. It was shown that stripping chronopotentiogram of copper (SCP) in the depletive mode is influenced by the adsorbed layer in the same manner as DPASV. The influence of the adsorbed NOM on pseudopolarographic measurements of copper and on determination of copper complexing capacity (CuCC) was demonstrated. A shift of the peak potential and the change of the half-peak width on the accumulation potential (for pseudopolarography) and on copper concentration in solution (for CuCC) were observed. By applying a desorption step these effects vanished, yielding different final results.

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

    PubMed

    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.

  19. Control of Pre-Tilt Angles of Liquid Crystal Molecules Using a Chemically Adsorbed Monomolecular Layer as an Alignment Film in Liquid Crystal Cells

    NASA Astrophysics Data System (ADS)

    Ogawa, Kazufumi; Ohtake, Tadashi; Nomura, Takaiki

    2002-11-01

    Photoaligned monomolecular layers containing two materials were formed to control pre-tilt angles (θp) of liquid crystal molecules for twisted nematic (TN) type liquid crystal displays (LCDs) by a chemical adsorption (CA) technique and a photoalignment technique. One was a new chlorosilane type surfactant, 4‧-(6-trichlorosilyloxyhexyloxy) chalcone (CO), having photopolymerizablity, and the other was a surfactant having a straight carbon chain (SC). Although we tried screening six different surfectants as an additive to CO, a surfactant having a long straight hydrocarbon chain (octadecyl-trichlorosilane: C18) was the most suitable for the TN type LCDs. By changing the molecular ratio of CO and C18, pre-tilt angles of liquid crystal molecules in a test liquid crystal (LC) cell could be controlled from 0 to 8° with perfect mono-domain alignment. When surfactants having short hydrocarbon chains and those having fluorocarbon chains were used, the quality of the TN type LC cells obtained was not good.

  20. Atomic force microscopy study of the interaction between adsorbed poly(ethylene oxide) layers: effects of surface modification and approach velocity.

    PubMed

    McLean, Scott C; Lioe, Hadi; Meagher, Laurence; Craig, Vincent S J; Gee, Michelle L

    2005-03-15

    The interaction forces between layers of the triblock copolymer Pluronic F108 adsorbed onto hydrophobic radio frequency glow discharge (RFGD) thin film surfaces and hydrophilic silica, in polymer-free 0.15 M NaCl solution, have been measured using the atomic force microscope (AFM) colloid probe technique. Compression of Pluronic F108 layers adsorbed on the hydrophobic RFGD surfaces results in a purely repulsive force due to the steric overlap of the layers, the form of which suggests that the PEO chains adopt a brush conformation. Subsequent fitting of these data to the polymer brush models of Alexander-de Gennes and Milner, Witten, and Cates confirms that the adsorbed Pluronic F108 adsorbs onto hydrophobic surfaces as a polymer brush with a parabolic segment density profile. In comparison, the interaction between Pluronic F108 layers adsorbed on silica exhibits a long ranged shallow attractive force and a weaker steric repulsion. The attractive component is reasonably well described by van der Waals forces, but polymer bridging cannot be ruled out. The weaker steric component of the force suggests that the polymer is less densely packed on the surface and is less extended into solution, existing as polymeric isolated mushrooms. When the surfaces are driven together at high piezo ramp velocities, an additional repulsive force is measured, attributable to hydrodynamic drainage forces between the surfaces. In comparing theoretical predictions of the hydrodynamic force to the experimentally obtained data, agreement could only be obtained if the flow profile of the aqueous solution penetrated significantly into the polymer brush. This finding is in line with the theoretical predictions of Milner and provides further evidence that the segment density profile of the adsorbed polymer brush is parabolic. A velocity dependent additional stepped repulsive force, reminiscent of a solvation oscillatory force, is also observed when the adsorbed layers are compressed under high

  1. Interactions of structurally modified surfactants with reservoir minerals: Calorimetric, spectroscopic and electrokinetic study

    SciTech Connect

    Somasundaran, P.; Sivakumar, A.; Xu, Q.

    1991-03-01

    The objective of this project is to elucidate mechanisms of adsorption of structurally modified surfactants on reservoir minerals and to develop a full understanding of the effect of the surfactant structure on the nature of the adsorbed layers at the molecular level. An additional aim is to study the adsorption of surfactant mixtures on simple well-characterized minerals and on complex minerals representing real conditions. The practical goal of these studies is the identification of the optimum surfactant structures and their combinations for micellar flooding. In this work, the experiments on adsorption were focussed on the position of sulfonate and methyl groups on the aromatic ring of alkyl xylene sulfonates. A multi-pronged approach consisting of calorimetry, electrokinetics, wettability and spectroscopy is planned to elucidate the adsorption mechanism of surfactants and their mixtures on minerals such as alumina and kaolinite. 32 refs., 15 figs., 7 tabs.

  2. Soap opera : polymer-surfactant interactions on thin film surfaces /

    SciTech Connect

    Ozer, B. H.; Johal, M. S.; Wang, H. L.; Robinson, J. 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

  3. Work-function oscillations during the surfactant induced layer-by-layer growth of copper on oxygen precovered Ru(0001)

    NASA Astrophysics Data System (ADS)

    Schmidt, M.; Wolter, H.; Wandelt, K.

    1994-04-01

    In the present work the Cu-film growth on a clean and an oxygen precovered Ru(0001) surface, as monitored with dynamical work function measurements (ΔΦ measurements) during the Cu evaporation using a special Kelvin-probe is compared. For Cu adsorption on the clean surface the observed temperature dependence of the ΔΦ measurements is understood in terms of a change of the growth structure of the Cu films from layer-by-layer growth up to ~ 3 ML at ~ 600 K to a 3D-growth mode at ~ 400 K. In turn, as recently reported, in the case of Cu adsorption on the oxygen-precovered surface at ~ 400 K remarkable ΔΦ oscillations are observed, which could be resolved over many periods clearly indicating a layer-wise growth of high quality at this temperature. Furthermore, in the present paper we report on new and detailed results about the dependence of the ΔΦ oscillations on the oxygen precoverage as well as the Cu deposition rate.

  4. Changes in the adsorbate dipole layer with changing d-filling of the metal (II) (Co, Ni, Cu) phthalocyanines on Au(111).

    PubMed

    Xiao, Jie; Dowben, Peter A

    2009-02-01

    In combined photoemission and inverse photoemission spectroscopy studies, we observe changes in the metal phthalocyanine molecular orbital offsets with respect to the conducting gold substrate Fermi level, with the changing d-electron filling of the metal (II) (Co, Ni, Cu) phthalocyanines. The implication is that the interfacial dipole layer depends upon the choice of metal (Co, Ni, Cu) centers within the metal (II) phthalocyanines adsorbed on Au(111).

  5. Polymer-surfactant layered heterostructures by electropolymerization of phenosafranine in Langmuir-Blodgett films.

    PubMed

    Sawant, Shilpa N; Doble, Mukesh; Yakhmi, J V; Kulshreshtha, S K; Miyazaki, Akira; Enoki, Toshiaki

    2006-12-01

    Langmuir-Blodgett (LB) films of the water-soluble dye phenosafranine (PS) have been prepared by its adsorption from aqueous dye solution to an arachidic acid (AA) monolayer at the air-water interface. Atomic force microscopy (AFM) images of the LB films revealed the effect of change in pH of deposition on the degree of complexation of AA with the PS dye. Well-defined circular islands and holes were observed which disappeared with the increase in pH. Polarized absorption studies indicated that the dye molecules are oriented uniaxially with their long axis titled at a constant angle to the surface normal of the LB film. Within the restricted geometry of the LB film, the PS dye was electropolymerized to form a two-dimensional film of poly(phenosafranine) sandwiched between arachidic acid layers. The film was characterized by IR spectroscopy, cyclic voltammetry, and AFM. X-ray diffraction studies reveal the presence of a layer structure in the AA-PS LB film before and after polymerization. The polymer film showed highly anisotropic electrical conductivity of ca. 10 orders of magnitude. This indicates the formation of two-dimensional polyPS layers between arachidic acid layers resulting in a layered heterostructure film having alternate conducting and insulating regions. Also, the conductivity of the polyPS prepared from LB film was found to be approximately 2.5 times higher than the conductivity of polyPS prepared by solution polymerization method. PMID:17134212

  6. Hydrophobic, electrostatic, and dynamic polymer forces at silicone surfaces modified with long-chain bolaform surfactants.

    PubMed

    Rapp, Michael V; Donaldson, Stephen H; Gebbie, Matthew A; Das, Saurabh; Kaufman, Yair; Gizaw, Yonas; Koenig, Peter; Roiter, Yuri; Israelachvili, Jacob N

    2015-05-01

    Surfactant self-assembly on surfaces is an effective way to tailor the complex forces at and between hydrophobic-water interfaces. Here, the range of structures and forces that are possible at surfactant-adsorbed hydrophobic surfaces are demonstrated: certain long-chain bolaform surfactants-containing a polydimethylsiloxane (PDMS) mid-block domain and two cationic α, ω-quarternary ammonium end-groups-readily adsorb onto thin PDMS films and form dynamically fluctuating nanostructures. Through measurements with the surface forces apparatus (SFA), it is found that these soft protruding nanostructures display polymer-like exploration behavior at the PDMS surface and give rise to a long-ranged, temperature- and rate-dependent attractive bridging force (not due to viscous forces) on approach to a hydrophilic bare mica surface. Coulombic interactions between the cationic surfactant end-groups and negatively-charged mica result in a rate-dependent polymer bridging force during separation as the hydrophobic surfactant mid-blocks are pulled out from the PDMS interface, yielding strong adhesion energies. Thus, (i) the versatile array of surfactant structures that may form at hydrophobic surfaces is highlighted, (ii) the need to consider the interaction dynamics of such self-assembled polymer layers is emphasized, and (iii) it is shown that long-chain surfactants can promote robust adhesion in aqueous solutions. PMID:25504803

  7. Surface characterization and AFM imaging of mixed fibrinogen-surfactant films.

    PubMed

    Hassan, Natalia; Maldonado-Valderrama, Julia; Gunning, A Patrick; Morris, Victor J; Ruso, Juan M

    2011-05-19

    This study describes the adsorption behavior of mixed protein/surfactant systems at the air-water interface: specifically fibrinogen and the fluorinated and hydrogenated surfactants (C(8)FONa, C(8)HONa, and C(12)HONa). Surface tension techniques and atomic force microscopy (AFM) have been combined to investigate the adsorption behavior of these mixed systems. Interfacial rheology showed that fibrinogen has a low dilatational modulus at the air-water interface when compared to other proteins, suggesting the formation of a weak surface network. Fluorinated and hydrogenated surfactants severely decreased the dilatational modulus of the adsorbed fibrinogen film at the air-water interface. These measurements suggest the progressive displacement of fibrinogen from the air-water interface by both types of surfactants. However, in the case of fibrinogen/fluorinated surfactant systems, surface tension and dilatational rheology measurements suggest the formation of complexes with improved surface activity. AFM imaging of fibrinogen in the presence and absence of surfactants provided new information on the structure of mixed surface films, and revealed new features of the interaction of fibrinogen with hydrogenated and fluorinated surfactants. These studies suggest complexes formed between fibrinogen and fluorinated surfactants which are more surface active than fibrinogen, while the absence of interaction between fibrinogen and hydrogenated surfactants (C(8)HONa and C(12)HONa) results in compaction of the surface layer.

  8. Mode instabilities and dynamic patterns in a colony of self-propelled surfactant particles covering a thin liquid layer.

    PubMed

    Pototsky, Andrey; Thiele, Uwe; Stark, Holger

    2016-05-01

    We consider a colony of point-like self-propelled surfactant particles (swimmers) without direct interactions that cover a thin liquid layer on a solid support. The particles predominantly swim normal to the free film surface with only a small component parallel to the film surface. The coupled dynamics of the swimmer density and film height profile is captured in a long-wave model allowing for diffusive and convective transport of the swimmers (including rotational diffusion). The dynamics of the film height profile is determined by i) the upward pushing force of the swimmers onto the liquid-gas interface, ii) the solutal Marangoni force due to gradients in the swimmer concentration, and iii) the rotational diffusion of the swimmers together with the in-plane active motion. After reviewing and extending the analysis of the linear stability of the uniform state, we analyse the fully nonlinear dynamic equations and show that point-like swimmers, which only interact via long-wave deformations of the liquid film, self-organise in highly regular (standing, travelling, and modulated waves) and various irregular patterns. PMID:27145959

  9. Efficient removal of dyes by a novel magnetic Fe3O4/ZnCr-layered double hydroxide adsorbent from heavy metal wastewater.

    PubMed

    Chen, Dan; Li, Yang; Zhang, Jia; Li, Wenhui; Zhou, Jizhi; Shao, Li; Qian, Guangren

    2012-12-01

    A novel magnetic Fe(3)O(4)/ZnCr-layered double hydroxide adsorbent was produced from electroplating wastewater and pickling waste liquor via a two-step microwave hydrothermal method. Adsorption of methyl orange (MO) from water was studied using this material. The effects of three variables have been investigated by a single-factor method. The response surface methodology (RSM) based on Box-Behnken design was successfully applied to the optimization of the preparation conditions. The maximum adsorption capacity of MO was found to be 240.16 mg/g, indicating that this material may be an effective adsorbent. It was shown that 99% of heavy metal ions (Fe(2+), Fe(3+), Cr(3+), and Zn(2+)) can be effectively removed into precipitates and released far less in the adsorption process. In addition, this material with adsorbed dye can be easily separated by a magnetic field and recycled after catalytic regeneration with advanced oxidation technology. Meanwhile, kinetic models, FTIR spectra and X-ray diffraction pattern were applied to the experimental data to examine uptake mechanism. The boundary layer and intra-particle diffusion played important roles in the adsorption mechanisms. PMID:23122732

  10. Synthesis of double-wall nanoscrolls intercalated with polyfluorinated cationic surfactant into layered niobate and their magnetic alignment.

    PubMed

    Nabetani, Yu; Uchikoshi, Akino; Miyajima, Souki; Hassan, Syed Zahid; Ramakrishnan, Vivek; Tachibana, Hiroshi; Yamato, Masafumi; Inoue, Haruo

    2016-04-28

    The orientation of nanomaterials with an anisotropic nature such as nanoscrolls is very important for realizing their efficient and sophisticated functions in devices, including nanostructured electrodes in artificial photosynthetic cells. In this study, we successfully synthesized a nanoscroll by intercalation of a cationic polyfluorinated surfactant into the interlayer spaces of layered niobate and successfully controlled its orientation by applying an external magnetic field in water. The exfoliated niobate nanosheets were efficiently rolled-up to form nanoscrolls, which have a fine layered structure (d020 = 3.64 nm), by mixing with heptafluorobutanoylaminoethylhexadecyldimethylammonium bromide (C3F-S) in water, whereas the corresponding hydrocarbon analogue (C3H-S) did not form nanoscrolls. The synthetic yield for the purified and isolated nanoscrolls from the nanosheets was estimated to be 62% by weight. It was confirmed by atomic force microscopy (AFM) that most of the niobate nanosheets (98%) were converted to nanoscrolls. An external magnetic field was applied to the nanoscrolls to force them to align. After the magnetic treatment, the orientation of the nanoscrolls was investigated by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The non-uniform ring distribution of the SAXS patterns indicates that the nanoscrolls dispersed in water were aligned well on applying the magnetic field. The long axis of the nanoscroll was oriented in the direction of the applied field and long nanoscrolls were aligned more efficiently. When the intercalated C3F-S molecules were removed from the nanoscrolls by treating with an acid, the resultant nanoscrolls did not exhibit magnetic alignment, strongly suggesting that C3F-S plays an important role in the orientation control of the nanoscrolls by the magnetic field. PMID:27074750

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

    SciTech Connect

    Somasundaran, P.

    1994-07-01

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

  12. Synthesis of Au-CeO 2/SiO 2 catalyst via adsorbed-layer reactor technique combined with alcohol-thermal treatment

    NASA Astrophysics Data System (ADS)

    Jiang, Xin; Deng, Hui

    2011-10-01

    Au-CeO 2/SiO 2 was prepared via adsorbed-layer reactor technique combined with alcohol-thermal treatment. The catalytic performance in complete oxidation of benzene was investigated. TEM, Raman characterization showed that Au particles grew up obviously during alcohol-thermal process, while CeO 2 particles maintained 4 nm in diameter. The content of oxygen vacancies and adsorbed oxygen species on catalysts surface increased apparently. Alcohol-thermally treated Au-CeO 2/SiO 2 and CeO 2/SiO 2 showed similar change in catalytic performance, and were much superior to calcined CeO 2/SiO 2. Of alcohol-thermally treated and calcined CeO 2/SiO 2, initial temperatures of the reaction were 80 °C and 150 °C, respectively. The benzene conversions reached 85% and 40% at 300 °C.

  13. Linking the Presence of Surfactant Associated Bacteria on the Sea Surface and in the Near Surface Layer of the Ocean to Satellite Imagery

    NASA Astrophysics Data System (ADS)

    Hamilton, Bryan; Dean, Cayla; Kurata, Naoko; Soloviev, Alex; Tartar, Aurelien; Shivji, Mahmood; Perrie, William; Lehner, Susanne

    2015-04-01

    Several genera of bacteria residing on the sea surface and in the near-surface layer of the ocean have been found to be involved in the production and decay of surfactants. Under low wind speed conditions, these surfactants can suppress short gravity capillary waves at the sea surface and form natural sea slicks. These features can be observed with both airborne and satellite-based synthetic aperture radar (SAR). We have developed a new method for sampling the sea surface microlayer that has reduced contamination from the boat and during lab handling of samples. Using this new method, a series of experiments have been conducted to establish a connection between the presence of surfactant-associated bacteria in the upper layer of the ocean and sea slicks. DNA analysis of in situ samples taken during a RADARSAT-2 satellite overpass in the Straits of Florida during the 2010 Deepwater Horizon oil spill showed a higher abundance of surfactant-associated bacterial genera in the slick area as compared to the non-slick area. These genera were found to be more abundant in the subsurface water samples collected as compared to samples taken from the sea surface. The experiment was repeated in the Straits of Florida in September 2013 and was coordinated with TerraSAR-X satellite overpasses. The observations suggest that the surfactants contributing to sea slick formation are produced by marine bacteria in the organic matter-rich water column and move to the sea surface by diffusion or advection. Thus, within a range of wind-wave conditions, the organic materials present in the water column (such as dissolved oil spills) can be monitored with SAR satellite imagery. In situ sampling was also performed in the Gulf of Mexico in December 2013 during RADARSAT-2 and TerraSAR-X satellite overpasses. Areas near natural oil seeps identified from archived TerraSAR-X imagery were targeted for in situ sampling. A number of samples from this location have been analyzed to determine the

  14. Surfactant titration of nanoparticle-protein corona.

    PubMed

    Maiolo, Daniele; Bergese, Paolo; Mahon, Eugene; Dawson, Kenneth A; Monopoli, Marco P

    2014-12-16

    Nanoparticles (NP), when exposed to biological fluids, are coated by specific proteins that form the so-called protein corona. While some adsorbing proteins exchange with the surroundings on a short time scale, described as a "dynamic" corona, others with higher affinity and long-lived interaction with the NP surface form a "hard" corona (HC), which is believed to mediate NP interaction with cellular machineries. In-depth NP protein corona characterization is therefore a necessary step in understanding the relationship between surface layer structure and biological outcomes. In the present work, we evaluate the protein composition and stability over time and we systematically challenge the formed complexes with surfactants. Each challenge is characterized through different physicochemical measurements (dynamic light scattering, ζ-potential, and differential centrifugal sedimentation) alongside proteomic evaluation in titration type experiments (surfactant titration). 100 nm silicon oxide (Si) and 100 nm carboxylated polystyrene (PS-COOH) NPs cloaked by human plasma HC were titrated with 3-[(3-Cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS, zwitterionic), Triton X-100 (nonionic), sodium dodecyl sulfate (SDS, anionic), and dodecyltrimethylammonium bromide (DTAB, cationic) surfactants. Composition and density of HC together with size and ζ-potential of NP-HC complexes were tracked at each step after surfactant titration. Results on Si NP-HC complexes showed that SDS removes most of the HC, while DTAB induces NP agglomeration. Analogous results were obtained for PS NP-HC complexes. Interestingly, CHAPS and Triton X-100, thanks to similar surface binding preferences, enable selective extraction of apolipoprotein AI (ApoAI) from Si NP hard coronas, leaving unaltered the dispersion physicochemical properties. These findings indicate that surfactant titration can enable the study of NP-HC stability through surfactant variation and also selective separation

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

    SciTech Connect

    Somasundaran, P.

    1995-06-01

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

  16. Surface rheology of PEO-PPO-PEO triblock copolymers at the air-water interface: comparison of spread and adsorbed layers.

    PubMed

    Blomqvist, B Rippner; Wärnheim, T; Claesson, P M

    2005-07-01

    The dilatational rheological properties of monolayers of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)-type block copolymers at the air-water interface have been investigated by employing an oscillating ring trough method. The properties of adsorbed monolayers were compared to spread layers over a range of surface concentrations. The studied polymers were PEO26-PPO39-PEO26 (P85), PEO103-PPO40-PEO103 (F88), and PEO99-PPO65-PEO99 (F127). Thus, two of the polymers have similar PPO block size and two of them have similar PEO block size, which allows us to draw conclusions about the relationship between molecular structure and surface dilatational rheology. The dilatational properties of adsorbed monolayers were investigated as a function of time and bulk solution concentration. The time dependence was found to be rather complex, reflecting structural changes in the layer. When the dilatational modulus measured at different concentrations was replotted as a function of surface pressure, one unique master curve was obtained for each polymer. It was found that the dilatational behavior of spread (Langmuir) and adsorbed (Gibbs) monolayers of the same polymer is close to identical up to surface concentrations of approximately 0.7 mg/m2. At higher coverage, the properties are qualitatively alike with respect to dilatational modulus, although some differences are noticeable. Relaxation processes take place mainly within the interfacial layers by a redistribution of polymer segments. Several conformational transitions were shown to occur as the area per molecule decreased. PEO desorbs significantly from the interface at segmental areas below 20 A(2), while at higher surface coverage, we propose that segments of PPO are forced to leave the interface to form a mixed sublayer in the aqueous region. PMID:15982044

  17. Adsorbent and adsorbent bed for materials capture and separation processes

    SciTech Connect

    Liu, Wei

    2011-01-25

    A method device and material for performing adsorption wherein a fluid mixture is passed through a channel in a structured adsorbent bed having a solid adsorbent comprised of adsorbent particles having a general diameter less than 100 um, loaded in a porous support matrix defining at least one straight flow channel. The adsorbent bed is configured to allow passage of a fluid through said channel and diffusion of a target material into said adsorbent under a pressure gradient driving force. The targeted molecular species in the fluid mixture diffuses across the porous support retaining layer, contacts the adsorbent, and adsorbs on the adsorbent, while the remaining species in the fluid mixture flows out of the channel.

  18. Co-adsorption of peptide amphiphile V(6)K and conventional surfactants SDS and C(12)TAB at the solid/water interface.

    PubMed

    Jayawardane, Dharana; Pan, Fang; Lu, Jian R; Zhao, Xiubo

    2015-10-28

    Recent research has reported many attractive benefits from short peptide amphiphiles. A practical route for them to enter the real world of applications is through formulation with conventional surfactants. This study reports the co-adsorption of the surfactant-like peptide, V6K, with conventional anionic and cationic surfactants at the solid/water interface. The time-dependant adsorption behaviour was examined using spectroscopic ellipsometry whilst adsorbed layer composition and structural distribution of the components were investigated by neutron reflection with the use of hydrogen/deuterium labelling of the surfactant molecules. Both binary (surfactant/peptide mixtures) and sequential (peptide followed by surfactant) adsorption have been studied. It was found that at the hydrophilic SiO2/water interface, the peptide was able to form a stable, flat, defected bilayer structure however both the structure and adsorbed amount were highly dependent on the initial peptide concentration. This consequently affected surfactant adsorption. In the presence of a pre-adsorbed peptide layer anionic sodium dodecyl sulfate (SDS) could readily co-adsorb at the interface; however, cationic dodecyl trimethyl ammonium bromide (C12TAB) could not co-adsorb due to the same charge character. However on a trimethoxy octyl silane (C8) coated hydrophobic surface, V6K formed a monolayer, and subsequent exposure to cationic and anionic surfactants both led to some co-adsorption at the interface. In binary surfactant/peptide mixtures, it was found that adsorption was dependent on the molar ratio of the surfactant and peptide. For SDS mixtures below molar unity and concentrations below CMC for C12TAB, V6K was able to dominate adsorption at the interface. Above molar unity, no adsorption was detected for SDS/V6K mixtures. In contrast, C12TAB gradually replaced the peptide and became dominant at the interface. These results thus elucidate the adsorption behaviour of V6K, which was found to

  19. Layered protonated titanate nanosheets synthesized with a simple one-step, low-temperature, urea-modulated method as an effective pollutant adsorbent.

    PubMed

    Lin, Cheng-Hsien; Wong, David Shan-Hill; Lu, Shih-Yuan

    2014-10-01

    A simple one-step, low-temperature, urea-modulated method is developed for the synthesis of layered protonated titanate nanosheets (LPTNs). Urea serves as an indirect ammonium ion source, and the controlled supply of the ammonium ion slows the crystalline formation process and enables the production of the LPTNs from amorphous intermediate through aging-induced restructuring. The resulting LPTNs exhibit excellent adsorption capacities for methylene blue and Pb(2+) because of their high specific surface areas and excellent ion-exchange capability. Intercalation of Pb(2+) into the interlayer space of the LPTNs is evidenced by the relevant X-ray diffraction patterns on perturbation of the layered structure. The LPTNs prove to be a promising adsorbent in wastewater treatment for adsorption removal of metal ions or cationic organic dyes. PMID:25198517

  20. Fullerene surfactants and their use in polymer solar cells

    SciTech Connect

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

    2015-12-15

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

  1. Surfactant Facilitated Spreading of Aqueous Drops on Hydrophobic Surfaces

    NASA Technical Reports Server (NTRS)

    Kumar, Nitin; Couzis, Alex; Maldarelli, Charles; Singh, Bhim S. (Technical Monitor)

    2000-01-01

    disks can form a space filling mat on the surface which removes a significant amount of the surface water. The water adjacent to the hydrophobic solid surface is of high energy due to incomplete hydrogen bonding; its removal significantly lowers the tension and reduces the contact angle. Hydrocarbon surfactants cannot remove as much surface water because their large polar groups prevent the chains from cohering lengthwise. In our report last year we presented a poster describing the preparation of model very hydrophobic surfaces which are homogeneous and atomically smooth using self assembled monolayers of octadecyl trichlorosilane (OTS). In this poster we will use these surfaces as test substrates in developing hydrocarbon based surfactant systems which superspread. We studied a binary hydrocarbon surfactant systems consisting of a very soluble large polar group polyethylene oxide surfactant (C12E6 (CH3(CH2)11(OCH2CH2)6OH) and a long chain alcohol dodecanol. By mixing the alcohol with this soluble surfactant we have found that the contact angle of the mixed system on our test hydrophobic surfaces is very low. We hypothesize that the alcohol fills in the gaps between adjacent adsorbed chains of the large polar group surfactant. This filling in removes the surface water and effects the decrease in contact angle. We confirm this hypothesis by demonstrating that at the air/water interface the mixed layer forms condensed phases while the soluble large polar group surfactant by itself does not. We present drop impact experiments which demonstrate that the dodecanol/C12E6 mixture is effective in causing impacting drops to spread on the very hydrophobic model OTS surfaces.

  2. Preparation and characterization of zwitterionic surfactant-modified montmorillonites.

    PubMed

    Zhu, Jianxi; Qing, Yanhong; Wang, Tong; Zhu, Runliang; Wei, Jingming; Tao, Qi; Yuan, Peng; He, Hongping

    2011-08-15

    A series of zwitterionic surfactant-modified montmorillonites (ZSMMs) were synthesized using montmorillonite and three zwitterionic surfactants with different alkyl chain lengths at different concentrations [0.2-4.0 cation exchange capacity (CEC)]. These ZSMMs were characterized by X-ray diffraction (XRD), thermo-gravimetric analysis and differential thermo-gravimetric (TG/DTG) analyses. The zwitterionic surfactant could be intercalated into the interlayer spaces of montmorillonites and causing interlayer space-swelling. From XRD measurements, the amount of the surfactants loaded and the basal spacing increased with surfactant concentration and alkyl chain length. One endothermic DTG peak occurred at ~390 °C, which was assigned to the decomposition of the zwitterionic surfactant on the organo-montmorillonites from 0.2 to 0.6 CEC. When the surfactant loading was increased, a new endothermic peak appeared at ~340 °C. From the microstructures of these ZSMMs, the mechanism of zwitterionic surfactant adsorption was proposed. At relatively low loadings of the zwitterionic surfactant, most of surfactants enter the spacing by an ion-exchange mechanism and are adsorbed onto the interlayer cation sites. When the concentration of the zwitterionic surfactant exceeds the CEC of montmorillonite, the surfactant molecules then adhere to the surface-adsorbed surfactant. Some surfactants enter the interlayers, whereas the others are attached to the clay surface. When the concentration of surfactant increases further beyond 2.0 CEC, the surfactants may occupy the inter-particle space within the house-of-cards aggregate structure.

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

    PubMed

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

    2014-05-13

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

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

    PubMed

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

    2014-05-13

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

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

    PubMed

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

    2008-12-16

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

  6. Magnetized graphene layers synthesized on the carbon nanofibers as novel adsorbent for the extraction of polycyclic aromatic hydrocarbons from environmental water samples.

    PubMed

    Rezvani-Eivari, Mostafa; Amiri, Amirhassan; Baghayeri, Mehdi; Ghaemi, Ferial

    2016-09-23

    The application of magnetized graphene (G) layers synthesized on the carbon nanofibers (CNFs) (m-G/CNF) was investigated as novel adsorbent for the magnetic solid-phase extraction (MSPE) of polycyclic aromatic hydrocarbons (PAHs) in water samples followed by gas chromatography-flame ionization detector (GC-FID). Six important parameters, affecting the extraction efficiency of PAHs, including: amount of adsorbent, adsorption and desorption times, type and volume of the eluent solvent and salt content of the sample were evaluated. The optimum extraction conditions were obtained as: 5min for extraction time, 20mg for sorbent amount, dichloromethane as desorption solvent, 1mL for desorption solvent volume, 5min for desorption time and 15% (w/v) for NaCl concentration. Good performance data were obtained at the optimized conditions. The calibration curves were linear over the concentration ranges from 0.012 to 100ngmL(-1) with correlation coefficients (r) between 0.9950 and 0.9967 for all the analytes. The limits of detection (LODs, S/N=3) of the proposed method for the studied PAHs were 0.004-0.03ngmL(-1). The relative standard deviations (RSDs) for five replicates at two concentration levels (0.1 and 50ngmL(-1)) of PAHs were ranged from 3.4 to 5.7%. Appropriate relative recovery values, in the range of 95.5-99.9%, were also obtained for the real water sample analysis. PMID:27578405

  7. Adsorption layer properties of alkyltrimethylammonium bromides at interfaces between water and different alkanes.

    PubMed

    Mucic, N; Kovalchuk, N M; Aksenenko, E V; Fainerman, V B; Miller, R

    2013-11-15

    We measured the interfacial tensions of aqueous solutions against different oil phases using drop profile analysis tensiometry (PAT-1, Sinterface Technologies, Germany) for decyl- and dodecyltrimethylammonium bromide (C10TAB and C12TAB) in phosphate buffer (10 mM, pH7). The following alkanes were used as oil phases: hexane, heptane, octane, nonane, decane, dodecane and tetradecane. The obtained equilibrium interfacial tension isotherms were fitted by the Frumkin Ionic Compressibility model (FIC). The surfactants adsorb at the water/oil interface in competition with the oil molecules. At high surfactant surface coverage this competitive adsorption is manifested in two ways. First, for short chain surfactants, the oil molecules are embedded into the adsorption layer. Second, for long chain surfactants, the short alkane chains of the oil molecules are squeezed out from the adsorption layer due to strong mutual interaction between surfactants' chains. PMID:24011787

  8. Molecular mobility in the monolayers of foam films stabilized by porcine lung surfactant.

    PubMed Central

    Lalchev, Z I; Todorov, R K; Christova, Y T; Wilde, P J; Mackie, A R; Clark, D C

    1996-01-01

    Certain physical properties of a range of foam film types that are believed to exist in vivo in the lung have been investigated. The contribution of different lung surfactant components found in porcine lung surfactant to molecular surface diffusion in the plane of foam films has been investigated for the first time. The influence of the type and thickness of black foam films, temperature, electrolyte concentration, and extract composition on surface diffusion has been studied using the fluorescence recovery after photobleaching technique. Fluorescent phospholipid probe molecules in foam films stabilized by porcine lung surfactant samples or their hydrophobic extracts consisting of surfactant lipids and hydrophobic lung surfactant proteins, SP-B and SP-C, exhibited more rapid diffusion than observed in films of its principal lipid component alone, L-alpha-phosphatidylcholine dipalmitoyl. This effect appears to be due to contributions from minor lipid components present in the total surfactant lipid extracts. The minor lipid components influence the surface diffusion in foam films both by their negative charge and by lowering the phase transition temperature of lung surfactant samples. In contrast, the presence of high concentrations of the hydrophillic surfactant protein A (SP-A) and non-lung-surfactant proteins in the sample reduced the diffusion coefficient (D) of the lipid analog in the adsorbed layer of the films. Hysteresis behavior of D was observed during temperature cycling, with the cooling curve lying above the heating curve. However, in cases where some surface molecular aggregation and surface heterogeneity were observed during cooling, the films became more rigid and molecules at the interfaces became immobilized. The thickness, size, capillary pressure, configuration, and composition of foam films of lung surfactant prepared in vitro support their investigation as realistic structural analogs of the surface films that exist in vivo in the lung

  9. Adsorbent phosphates

    NASA Technical Reports Server (NTRS)

    Watanabe, S.

    1983-01-01

    An adsorbent which uses as its primary ingredient phosphoric acid salts of zirconium or titanium is presented. Production methods are discussed and several examples are detailed. Measurements of separating characteristics of some gases using the salts are given.

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

    SciTech Connect

    P. Somasundaran

    2008-09-20

    /conformation of the adsorbed layers), as well as precipitation/abstraction characteristics. (3) Investigation of the role of dissolved species, especially multivalent ions, on interactions between reservoir minerals and surfactants and/or polymers leading to surfactant precipitation or activated adsorption. (4) Solution behavior tests--surface tension, interaction, ultra filtration, and other tests. (5) Surfactant-mineral interactions relative to adsorption, wettability, and electrophoresis. (6) Work on the effects of multivalent ions, pH, temperature, salinity, and mixing ratio on the adsorption. Developments of adsorption models to explain interactions between surfactants/polymers/minerals. (7) General guidelines for the use of certain surfactants, polymers and their mixtures in micelle flooding processes.

  11. The biophysical function of pulmonary surfactant.

    PubMed

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

    2008-11-30

    Pulmonary surfactant lowers surface tension in the lungs. Physiological studies indicate two key aspects of this function: that the surfactant film forms rapidly; and that when compressed by the shrinking alveolar area during exhalation, the film reduces surface tension to very low values. These observations suggest that surfactant vesicles adsorb quickly, and that during compression, the adsorbed film resists the tendency to collapse from the interface to form a 3D bulk phase. Available evidence suggests that adsorption occurs by way of a rate-limiting structure that bridges the gap between the vesicle and the interface, and that the adsorbed film avoids collapse by undergoing a process of solidification. Current models, although incomplete, suggest mechanisms that would partially explain both rapid adsorption and resistance to collapse as well as how different constituents of pulmonary surfactant might affect its behavior. PMID:18632313

  12. Kinetic multi-layer model of the epithelial lining fluid (KM-ELF): Reactions of ozone and OH with antioxidants and surfactant molecules

    NASA Astrophysics Data System (ADS)

    Lakey, Pascale; Pöschl, Ulrich; Shiraiwa, Manabu

    2015-04-01

    Oxidants cause damage to biosurfaces such as the lung epithelium unless they are effectively scavenged. The respiratory tract is covered in a thin layer of fluid which extends from the nasal cavity to the alveoli and contain species that scavenge ozone and other incoming oxidants. The kinetic multi-layer model of the epithelial lining fluid (KM-ELF) has been developed in order to investigate the reactions of ozone and OH with antioxidants (ascorbate, uric acid, glutathione and α-tocopherol) and surfactant lipids and proteins within the epithelial lining fluid (ELF). The model incorporates different processes: gas phase diffusion, adsorption and desorption from the surface, bulk phase diffusion and known reactions at the surface and in the bulk. The ELF is split into many layers: a sorption layer, a surfactant layer, a near surface bulk layer and several bulk layers. Initial results using KM-ELF indicate that at ELF thicknesses of 80 nm and 1 × 10-4cm the ELF would become rapidly saturated with ozone with saturation occurring in less than a second. However, at an ELF thickness of 1 × 10-3cm concentration gradients were observed throughout the ELF and the presence of antioxidants reduced the O3 reaching the lung cells and tissues by 40% after 1 hour of exposure. In contrast, the antioxidants were efficient scavengers of OH radicals, although the large rate constants of OH reacting with the antioxidants resulted in the antioxidants decaying away rapidly. The chemical half-lives of the antioxidants and surface species were also calculated using KM-ELF as a function of O3 and OH concentration and ELF thickness. Finally, the pH dependence of the products of reactions between antioxidants and O3 were investigated. The KM-ELF model predicted that a harmful ascorbate ozonide product would increase from 1.4 × 1011cm-3at pH 7.4 to 1.1 × 1014 cm-3 at pH 4after 1 hour although a uric acid ozonide product would decrease from 2.0 × 1015cm-3to 5.9 × 1012cm-3.

  13. Vacuum space charge effects in sub-picosecond soft X-ray photoemission on a molecular adsorbate layer

    DOE PAGES

    Dell'Angela, M.; Anniyev, T.; Beye, M.; Coffee, R.; Föhlisch, A.; Gladh, J.; Kaya, S.; Katayama, T.; Krupin, O.; Nilsson, A.; et al

    2015-03-01

    Vacuum space charge-induced kinetic energy shifts of O 1s and Ru 3d core levels in femtosecond soft X-ray photoemission spectra (PES) have been studied at a free electron laser (FEL) for an oxygen layer on Ru(0001). We fully reproduced the measurements by simulating the in-vacuum expansion of the photoelectrons and demonstrate the space charge contribution of the high-order harmonics in the FEL beam. Employing the same analysis for 400 nm pump-X-ray probe PES, we can disentangle the delay dependent Ru 3d energy shifts into effects induced by space charge and by lattice heating from the femtosecond pump pulse.

  14. A comparison of didodecyldimethylammonium bromide adsorbed at mica/water and silica/water interfaces using neutron reflection.

    PubMed

    Griffin, Lucy R; Browning, Kathryn L; Truscott, Chris L; Clifton, Luke A; Webster, John; Clarke, Stuart M

    2016-09-15

    The layer structure of the dichain alkyl ammonium surfactant, didodecyldimethylammonium bromide (DDAB), adsorbed from water on to silica and mica surfaces has been determined using neutron reflection. Although sometimes considered interchangeable surfaces for study, we present evidence of significant differences in the adsorbed layer structure below the critical micelle concentration. A complete DDAB bilayer was assembled at the water/mica interface at concentrations below the critical micelle concentration (CMC). In contrast it is not until the CMC was reached that the complete bilayer structure formed on the oxidised silicon crystal. Removal of the complete bilayer on both surfaces was attempted by both washing and ion exchange yet the adsorbed structure proved tenacious. PMID:27318715

  15. Surfactant-assisted encapsulation of uniform SnO2 nanoparticles in graphene layers for high-performance Li-storage

    NASA Astrophysics Data System (ADS)

    Ai, Wei; Zhu, Jianhui; Jiang, Jian; Chao, Dongliang; Wang, Yanlong; Ng, Chin Fan; Wang, Xiuli; Wu, Chao; Li, Changming; Shen, Zexiang; Huang, Wei; Yu, Ting

    2015-03-01

    SnO2/graphene composite has been regarded as the alternative anode material for next generation high-performance lithium-ion batteries (LIBs). Here we report an efficient and facile one-pot strategy for the synthesis of SnO2/graphene composite through a surfactant-assisted redox process. The presence of surfactant can provide homogeneous nucleation sites for SnO2 nanoparticles formation, thus ensuring the generated SnO2 nanoparticles have a tiny size of ˜5 nm and are uniformly distributed on the graphene sheets. Simultaneously, the random aggregation of graphene sheets leads to the in-situ encapsulation of SnO2 nanoparticles into graphene layers, forming a mechanically robust composite structure. These unique structural features are not only favorable for fast electrons transport and Li ions diffusion, but also capable of effectively buffering the volume changes of SnO2 nanoparticles. As a consequence, the SnO2/graphene composite exhibits superior Li storage performance in terms of large reversible capacity, good cycling stability and excellent rate capability.

  16. Vacuum space charge effects in sub-picosecond soft X-ray photoemission on a molecular adsorbate layer.

    PubMed

    Dell'Angela, M; Anniyev, T; Beye, M; Coffee, R; Föhlisch, A; Gladh, J; Kaya, S; Katayama, T; Krupin, O; Nilsson, A; Nordlund, D; Schlotter, W F; Sellberg, J A; Sorgenfrei, F; Turner, J J; Öström, H; Ogasawara, H; Wolf, M; Wurth, W

    2015-03-01

    Vacuum space charge induced kinetic energy shifts of O 1s and Ru 3d core levels in femtosecond soft X-ray photoemission spectra (PES) have been studied at a free electron laser (FEL) for an oxygen layer on Ru(0001). We fully reproduced the measurements by simulating the in-vacuum expansion of the photoelectrons and demonstrate the space charge contribution of the high-order harmonics in the FEL beam. Employing the same analysis for 400 nm pump-X-ray probe PES, we can disentangle the delay dependent Ru 3d energy shifts into effects induced by space charge and by lattice heating from the femtosecond pump pulse.

  17. Vacuum space charge effects in sub-picosecond soft X-ray photoemission on a molecular adsorbate layer.

    PubMed

    Dell'Angela, M; Anniyev, T; Beye, M; Coffee, R; Föhlisch, A; Gladh, J; Kaya, S; Katayama, T; Krupin, O; Nilsson, A; Nordlund, D; Schlotter, W F; Sellberg, J A; Sorgenfrei, F; Turner, J J; Öström, H; Ogasawara, H; Wolf, M; Wurth, W

    2015-03-01

    Vacuum space charge induced kinetic energy shifts of O 1s and Ru 3d core levels in femtosecond soft X-ray photoemission spectra (PES) have been studied at a free electron laser (FEL) for an oxygen layer on Ru(0001). We fully reproduced the measurements by simulating the in-vacuum expansion of the photoelectrons and demonstrate the space charge contribution of the high-order harmonics in the FEL beam. Employing the same analysis for 400 nm pump-X-ray probe PES, we can disentangle the delay dependent Ru 3d energy shifts into effects induced by space charge and by lattice heating from the femtosecond pump pulse. PMID:26798795

  18. Friction and adsorption of aqueous polyoxyethylene (Tween) surfactants at hydrophobic surfaces.

    PubMed

    Graca, Malgorzata; Bongaerts, Jeroen H H; Stokes, Jason R; Granick, Steve

    2007-11-15

    The nanotribological responses of a series of nonionic polyoxyethylene surfactants (Tween 20, Tween 40, Tween 60, and Tween 80) were investigated after they were adsorbed from aqueous solution onto atomically smooth hydrophobic substrates. The hydrophobic surfaces were composed of a condensed monolayer of octadecyltriethoxysilane (OTE; contact angle theta>110 degrees ). The nanorheological measurements were performed using a modified surface forces apparatus after coating atomically smooth mica with these OTE monolayers, while adsorption measurements were performed using phase-modulated ellipsometry on silicon wafers coated with these same monolayers. The minimum surface-surface separation observed under high load in friction studies agreed quantitatively with the thickness obtained from ellipsometry. For Tweens 20, 40, and 60, the thickness of the adsorbed film increases with increasing alkyl chain length. Systematic investigations of the nanorheological response showed that there is a "solid-like" elastic response from confined surfactant layers, which is the case for the smallest separations to separations up to slightly larger than twice the adsorbed film thickness. In kinetic friction, these confined layers are characterized by a shear stress of approximately 3 MPa with minimal dependence on shear rate. The magnitude of the sliding shear stress is the same as the apparent yield stress at approximately 3 MPa; it is independent of alkyl chain length within the Tween family of surfactants and corresponds to a nominal friction coefficient of mu approximately 1. A similar friction coefficient is observed for boundary lubrication on the macroscopic scale in a tribometer utilizing hydrophobic surfaces and mu approximately 1.1 for Tweens 20, 40, and 60. These results suggest that while Tween molecules adsorb onto hydrophobic surfaces to form a robust separating layer, the lubricating properties of these layers are dominated by a highly dissipative slip plane, the same

  19. Influence of surface chemistry on the structural organization of monomolecular protein layers adsorbed to functionalized aqueous interfaces.

    PubMed Central

    Lösche, M; Piepenstock, M; Diederich, A; Grünewald, T; Kjaer, K; Vaknin, D

    1993-01-01

    The molecular organization of streptavidin (SA) bound to aqueous surface monolayers of biotin-functionalized lipids and binary lipid mixtures has been investigated with neutron reflectivity and electron and fluorescence microscopy. The substitution of deuterons (2H) for protons (1H), both in subphase water molecules and in the alkyl chains of the lipid surface monolayer, was utilized to determine the interface structure on the molecular length scale. In all cases studied, the protein forms monomolecular layers underneath the interface with thickness values of approximately 40 A. A systematic dependence of the structural properties of such self-assembled SA monolayers on the surface chemistry was observed: the lateral protein density depends on the length of the spacer connecting the biotin moiety and its hydrophobic anchor. The hydration of the lipid head groups in the protein-bound state depends on the dipole moment density at the interface. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 5 FIGURE 11 FIGURE 12 FIGURE A1 PMID:8298041

  20. Effect of surfactant on temperature stability of solid lipid nanoparticles studied by dynamic light scattering

    NASA Astrophysics Data System (ADS)

    Kumar, Sacheen; Kaur, Jaspreet

    2013-06-01

    Solid lipid nanoparticles are new paradigm of drug delivery system of water insoluble active pharmaceutical ingredient. Paliperidone, an antipsychotic used in treatment of schizophrenia is a water insoluble molecule with low bioavailability was studied. Macrogol glyceride surfactant, bile salt based surfactant and sodium dodecyl sulphate were used to stabilize the solid lipid as dispersed nanoparticles form by adsorbing on the surface of the nanoparticles. Anionic surfactants bile salt and sodium dodecyl sulphate were found to stabilize forming a monomolecular layer of surfactants on the surface of nanoparticles; whereas macrogol glyceride based surfactant have intrusion in the matrix of lipid nanoparticles. So intrusion of macrogol glyceride in matrix was observed by studying the change in size of nanoparticles with respect to temperature with the help of dynamic light scattering. In case of macrogol glyceride size decrease start form 50°C, for bile salt and sodium dodecyl sulphate size deacrease start at 60°C. So that structural disturbance of nanoparticles by the macrogol glyceride on the surface was found maximum as compared to anionic surfactant.

  1. Lung surfactant.

    PubMed Central

    Rooney, S A

    1984-01-01

    Aspects of pulmonary surfactant are reviewed from a biochemical perspective. The major emphasis is on the lipid components of surfactant. Topics reviewed include surfactant composition, cellular and subcellular sites as well as pathways of biosynthesis of phosphatidylcholine, disaturated phosphatidylcholine and phosphatidylglycerol. The surfactant system in the developing fetus and neonate is considered in terms of phospholipid content and composition, rates of precursor incorporation, activities of individual enzymes of phospholipid synthesis and glycogen content and metabolism. The influence of the following hormones and other factors on lung maturation and surfactant production is discussed: glucocorticoids, thyroid hormone, estrogen, prolactin, cyclic AMP, beta-adrenergic and cholinergic agonists, prostaglandins and growth factors. The influence of maternal diabetes, fetal sex, stress and labor are also considered. Nonphysiologic and toxic agents which influence surfactant in the fetus, newborn and adult are reviewed. PMID:6145585

  2. Adsorption of polyoxyethylenic surfactants on quartz, kaolin, and dolomite: A correlation between surfactant structure and solid surface nature

    SciTech Connect

    Nevskaia, D.M.; Guerrero-Ruiz, A.; Lopez-Gonzalez, J.deD.

    1996-08-10

    Adsorption of a surfactant at a liquid-solid interface makes up the basis of many technological processes such as detergency, flotation, water treatment, and enhanced oil recovery. The influence of variables such as adsorption temperature, polar chain length, and nature of functional groups on the adsorption, from aqueous solutions, of various surfactants (TX-114, TX-100, TX-165, TX-305, NP1P4E, NP4P1E, NP4S, NP10S, and NP25S) has been investigated. Several nonporous solids, including various samples of quartz, kaolin, and dolomite, were studied. Conformational changes of adsorbed surfactant molecules on one quartz, when the oxyethylenic length of Tritons increases, have been detected. For all the other solid samples the surface is not completely covered by Tritons. On quartz, the surfactants are adsorbed by hydrogen bonds between the surfactant`s ether groups and the silanol groups of the solid surface. These hydroxyl groups must be free and sufficiently separated from other hydroxyls of the solid surface. When the number of propoxy groups increases (from NP1P4E to NP4P1E) the adsorbed amount of surfactant on the solid studied decreases. Anionic surfactants are adsorbed on quartz in lower amounts than the corresponding nonionic surfactants. However, the adsorbed amounts of Tritons and sulfated Tritons on kaolin are similar, probably due to the positive charges on the edges of this material.

  3. Adsorption properties of the nanozirconia/anionic polyacrylamide system-Effects of surfactant presence, solution pH and polymer carboxyl groups content

    NASA Astrophysics Data System (ADS)

    Wiśniewska, Małgorzata; Chibowski, Stanisław; Urban, Teresa

    2016-05-01

    The adsorption mechanism of anionic polyacrylamide (PAM) on the nanozirconia surface was examined. The effects of solution pH, carboxyl groups content in macromolecules and anionic surfactant (sodium dodecyl sulfate-SDS) addition were determined. The more probable structure of polymer adsorption layer was characterized based on the data obtained from spectrophotometry, viscosimetry and potentiometric titration methods. The adsorbed amount of polymer, size of macromolecules in the solution and surface charge density of ZrO2 particles in the absence and presence of PAM were assessed, respectively. Analysis of these results indicated that the increase of solution pH and content of carboxyl groups in the polymeric chains lead to more expanded conformations of adsorbing macromolecules. As a result, the adsorption of anionic polyacrylamide decreased. The SDS presence caused the significant increase of PAM adsorbed amount at pH 3, whereas at pH 6 and 9 the surfactant addition resulted in reduction of polymer adsorption level.

  4. Surfactant-enhanced cellulose nanocrystal Pickering emulsions.

    PubMed

    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.

  5. The effect of temperatures and γ-ray irradiation on silica-based calix[4]arene-R14 adsorbent modified with surfactants for the adsorption of cesium from nuclear waste solution

    NASA Astrophysics Data System (ADS)

    Chen, Zi; Wu, Yan; Wei, Yuezhou

    2014-10-01

    1,3-[(2,4-Diethylheptylethoxy)oxy]-2,4-crown-6-Calix[4]arene(Calix[4]arene-R14), used as an extractant of Cs(I) from nitric acid, modified by dodecanol and dodecyl benzenesulfonic acid (DBS), was loaded into the pores of macroporous silica-based polymer support (SiO2-P) particles. To evaluate the stability of the adsorbent, the adsorption data at different temperatures (298-323 K) and γ-ray absorbed doses (10-200 kGy) were analyzed by the Langmuir isotherm. The minimum adsorbed amount was calculated to be 0.121 mmol g-1 at 323 K, approximately 23% reduction compared to 298 K. The maximum adsorbed amount of not-irradiated adsorbent with 0.156 mmol g-1 decreased by 20% than that irradiated in 0.5 M HNO3. The thermodynamic parameters have revealed that this adsorption reaction is an exothermic and spontaneous process. The reduction in 3 M HNO3 was about 45% by the comparison between the before- and after-irradiation. It was found that both the concentrations of HNO3 and DBS have significant influence on the degradation of the adsorbents.

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

    SciTech Connect

    P. Somasundaran

    2005-04-30

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

  7. Interaction of Moringa oleifera seed protein with a mineral surface and the influence of surfactants.

    PubMed

    Kwaambwa, Habauka M; Hellsing, Maja S; Rennie, Adrian R; Barker, Robert

    2015-06-15

    The paper describes the adsorption of purified protein from seeds of Moringa oleifera to a sapphire interface and the effects of addition of the anionic surfactant sodium dodecylsulfate (SDS) and the cationic surfactant hexadecyltrimethylammonium bromide (CTAB). Neutron reflection was used to determine the structure and composition of interfacial layers adsorbed at the solid/solution interface. The maximum surface excess of protein was found to be about 5.3 mg m(-2). The protein does not desorb from the solid/liquid interface when rinsed with water. Addition of SDS increases the reflectivity indicating co-adsorption. It was observed that CTAB is able to remove the protein from the interface. The distinct differences to the behavior observed previously for the protein at the silica/water interface are identified. The adsorption of the protein to alumina in addition to other surfaces has shown why it is an effective flocculating agent for the range of impurities found in water supplies. The ability to tailor different surface layers in combination with various surfactants also offers the potential for adsorbed protein to be used in separation technologies.

  8. Probing nanoparticle effect in protein-surfactant complexes

    NASA Astrophysics Data System (ADS)

    Mehan, Sumit; Aswal, V. K.; Kohlbrecher, J.

    2015-06-01

    SANS experiments have been carried to probe the role of anionic silica nanoparticles in the anionic BSA protein-cationic DTAB surfactant complexes. In protein-surfactant complex, surfactant molecules aggregate to form micelle-like clusters along the unfolded polypeptide chains of the protein. The nanoparticle aggregation mediated by oppositely charged protein-surfactant complex coexists with the free protein-surfactant complexes in the nanoparticle-protein-surfactant system. There is rearrangement of micelles in adsorbed protein-surfactant complex on nanoparticles in leading to their (nanoparticle) aggregation. On the other hand, the unfolding of protein in free protein-surfactant complex is found to be significantly enhanced in presence of nanoparticles.

  9. Heat transfer to the adsorbent in solar adsorption cooling device

    NASA Astrophysics Data System (ADS)

    Pilat, Peter; Patsch, Marek; Papucik, Stefan; Vantuch, Martin

    2014-08-01

    The article deals with design and construction of solar adsorption cooling device and with heat transfer problem in adsorber. The most important part of adsorption cooling system is adsorber/desorber containing adsorbent. Zeolith (adsorbent) type was chosen for its high adsorption capacity, like a coolant was used water. In adsorber/desorber occur, at heating of adsorbent, to heat transfer from heat change medium to the adsorbent. The time required for heating of adsorber filling is very important, because on it depend flexibility of cooling system. Zeolith has a large thermal resistance, therefore it had to be adapted the design and construction of adsorber. As the best shows the tube type of adsorber with double coat construction. By this construction is ensured thin layer of adsorbent and heating is quick in all volume of adsorbent. The process of heat transfer was experimentally measured, but for comparison simulated in ANSYS, too.

  10. Synthesis and surfactant modification of clinoptilolite and montmorillonite for the removal of nitrate and preparation of slow release nitrogen fertilizer.

    PubMed

    Bhardwaj, Deepesh; Sharma, Monika; Sharma, Pankaj; Tomar, Radha

    2012-08-15

    This article introduces the synthesis of clinoptilolite and montmorillonite, and their surfactant modification by using solutions of hexadecyltrimethylammonium bromide (CH(3)(CH(2))(15)N(Br)(CH(3))(3), HDTMAB) and dioctadecyldimethylammonium bromide ((CH(3)(CH(2))(17))(2)N(Br)(CH(3))(2), DODMAB). The feasibility of using surfactant modified silicates (SMSs) as a potential adsorbent for nitrate and for slow release of nutrient has been investigated. Adsorption isotherms of NO(3)(-) on SMSs have been measured at aqueous concentration of 160-280 mg L(-1). The SMSs show much higher adsorption capacity than the unmodified materials as determined by Langmuir adsorption isotherm. The surfactant modification and increased surfactant loading concentration enhance the nitrate anion retaining capacity of silicates (montmorillonite (16.05 mg g(-1))layers-funnel analytical test and soil column percolating system. The obtained results indicate that SMSs are very good adsorbent for NO(3)(-) and a slow release of nitrogen is achievable as it releases NO(3)(-) still after 15-20 days of leaching study.

  11. Interfacial Adsorption of Silk Fibroin Peptides and Their Interaction with Surfactants at the Solid-Water Interface.

    PubMed

    Jayawardane, Dharana; Pan, Fang; Lu, Jian R; Zhao, Xiubo

    2016-08-16

    Regenerated silk fibroin (RSF) is a Food and Drug Administration-approved material and has been widely used in many biomedical and cosmetic applications. Because of the amphiphilic nature of the primary repeat amino acid sequence (e.g., AGAGAS), RSF peptides can significantly reduce the water surface tension and therefore have the potential to be used as a surface active component for many applications, particularly in the biomedical, cosmetic, pharmaceutical, and food industries. In this paper, the adsorption of RSF peptides separated into molecular fractions of 5-30, 30-300, and >300 kDa has been studied at the solid-water interface by neutron reflection and spectroscopic ellipsometry to assess its surface active behavior. A stable layer of RSF was found to be irreversibly adsorbed at the hydrophilic SiO2-water interface. Changes in solution concentration, pH, and ionic strength all had an impact on the final adsorbed amount found at the interface. There were no significant differences between the final adsorbed amounts or layer structure among the three RSF molecular fractions studied; however, >300 kDa RSF was more stable to changes in solution ionic strength. Adsorption of conventional anionic and cationic surfactants, sodium dodecyl sulfate (SDS) and dodecyl trimethylammonium bromide (C12TAB), to the preadsorbed 5-30 kDa RSF revealed penetration of the surfactant into the RSF layer, at concentrations below the critical micellar concentration (CMC). SDS was found in the preadsorbed RSF layer and gradually removed RSF from the surface with an increase in SDS concentration. At concentrations above the CMC, there is near complete removal of RSF by SDS at the interface. C12TAB adsorbed into the preadsorbed RSF layer with considerably less removal of RSF from the interface compared to SDS. At concentrations above the CMC, both C12Tab and RSF were found to coexist at the interface, forming a less thick layer but with a considerable amount of RSF still present.

  12. Proteomic and Lipidomic Analysis of Nanoparticle Corona upon Contact with Lung Surfactant Reveals Differences in Protein, but Not Lipid Composition.

    PubMed

    Raesch, Simon Sebastian; Tenzer, Stefan; Storck, Wiebke; Rurainski, Alexander; Selzer, Dominik; Ruge, Christian Arnold; Perez-Gil, Jesus; Schaefer, Ulrich Friedrich; Lehr, Claus-Michael

    2015-12-22

    Pulmonary surfactant (PS) constitutes the first line of host defense in the deep lung. Because of its high content of phospholipids and surfactant specific proteins, the interaction of inhaled nanoparticles (NPs) with the pulmonary surfactant layer is likely to form a corona that is different to the one formed in plasma. Here we present a detailed lipidomic and proteomic analysis of NP corona formation using native porcine surfactant as a model. We analyzed the adsorbed biomolecules in the corona of three NP with different surface properties (PEG-, PLGA-, and Lipid-NP) after incubation with native porcine surfactant. Using label-free shotgun analysis for protein and LC-MS for lipid analysis, we quantitatively determined the corona composition. Our results show a conserved lipid composition in the coronas of all investigated NPs regardless of their surface properties, with only hydrophilic PEG-NPs adsorbing fewer lipids in total. In contrast, the analyzed NP displayed a marked difference in the protein corona, consisting of up to 417 different proteins. Among the proteins showing significant differences between the NP coronas, there was a striking prevalence of molecules with a notoriously high lipid and surface binding, such as, e.g., SP-A, SP-D, DMBT1. Our data indicate that the selective adsorption of proteins mediates the relatively similar lipid pattern in the coronas of different NPs. On the basis of our lipidomic and proteomic analysis, we provide a detailed set of quantitative data on the composition of the surfactant corona formed upon NP inhalation, which is unique and markedly different to the plasma corona. PMID:26575243

  13. Proteomic and Lipidomic Analysis of Nanoparticle Corona upon Contact with Lung Surfactant Reveals Differences in Protein, but Not Lipid Composition.

    PubMed

    Raesch, Simon Sebastian; Tenzer, Stefan; Storck, Wiebke; Rurainski, Alexander; Selzer, Dominik; Ruge, Christian Arnold; Perez-Gil, Jesus; Schaefer, Ulrich Friedrich; Lehr, Claus-Michael

    2015-12-22

    Pulmonary surfactant (PS) constitutes the first line of host defense in the deep lung. Because of its high content of phospholipids and surfactant specific proteins, the interaction of inhaled nanoparticles (NPs) with the pulmonary surfactant layer is likely to form a corona that is different to the one formed in plasma. Here we present a detailed lipidomic and proteomic analysis of NP corona formation using native porcine surfactant as a model. We analyzed the adsorbed biomolecules in the corona of three NP with different surface properties (PEG-, PLGA-, and Lipid-NP) after incubation with native porcine surfactant. Using label-free shotgun analysis for protein and LC-MS for lipid analysis, we quantitatively determined the corona composition. Our results show a conserved lipid composition in the coronas of all investigated NPs regardless of their surface properties, with only hydrophilic PEG-NPs adsorbing fewer lipids in total. In contrast, the analyzed NP displayed a marked difference in the protein corona, consisting of up to 417 different proteins. Among the proteins showing significant differences between the NP coronas, there was a striking prevalence of molecules with a notoriously high lipid and surface binding, such as, e.g., SP-A, SP-D, DMBT1. Our data indicate that the selective adsorption of proteins mediates the relatively similar lipid pattern in the coronas of different NPs. On the basis of our lipidomic and proteomic analysis, we provide a detailed set of quantitative data on the composition of the surfactant corona formed upon NP inhalation, which is unique and markedly different to the plasma corona.

  14. Effectiveness of the statistical potential in the description of fermions in a worm-algorithm path-integral Monte Carlo simulation of 3He atoms placed on a 4He layer adsorbed on graphite.

    PubMed

    Ghassib, Humam B; Sakhel, Asaad R; Obeidat, Omar; Al-Oqali, Amer; Sakhel, Roger R

    2012-01-01

    We demonstrate the effectiveness of a statistical potential (SP) in the description of fermions in a worm-algorithm path-integral Monte Carlo simulation of a few 3He atoms floating on a 4He layer adsorbed on graphite. The SP in this work yields successful results, as manifested by the clusterization of 3He, and by the observation that the 3He atoms float on the surface of 4He. We display the positions of the particles in 3D coordinate space, which reveal clusterization of the 3He component. The correlation functions are also presented, which give further evidence for the clusterization.

  15. Using Zn/Al layered double hydroxide as a novel solid-phase extraction adsorbent to extract polycyclic aromatic hydrocarbons at trace levels in water samples prior to the determination of gas chromatography-mass spectrometry.

    PubMed

    Liu, Yan-Long; Zhou, Jia-Bin; Zhao, Ru-Song; Chen, Xiang-Feng

    2012-09-01

    This paper demonstrates, for the first time, the great potential of using Zn/Al layered double hydroxide intercalated sodium dodecyl benzene sulfonate (Zn/Al-SDBS-LDH) as a solid-phase extraction (SPE) material in the extraction of persistent organic pollutants prior to the determination of gas chromatography-mass spectrometry in environmental water samples. Zn/Al-SDBS-LDH, a relatively inexpensive and simply prepared material, was synthesized and used as a SPE adsorbent to quantitatively determine the concentration of five polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. Factors affecting extraction efficiency, such as, eluent type, eluent volume, flow rate of sample, sample volume, and amount of adsorbent, were investigated and optimized in detail. Experimental results indicate that there is an excellent linear relationship between peak area and the concentration of PAHs over the range of 5-500 ng L(-1), and the precisions (relative standard deviation (RSD)) were 2.5-6.3% under the optimum conditions. Based on the ratio of chromatographic signal-to-base line noise (S/N = 3), the limits of detection could reach 1.2-3.2 ng L(-1). This novel method was successfully applied to the analysis of PAHs in environmental water samples. As such, we show here that the use of Zn/Al-SDBS-LDH as SPE adsorbent materials, coupled with gas chromatography-mass spectrometry, is an excellent improvement in the routine analysis of PAHs at trace levels in the environment.

  16. Characterizing the Effect of Salt and Surfactant Concentration on the Counterion Atmosphere around Surfactant Stabilized SWCNTs Using Analytical Ultracentrifugation.

    PubMed

    Lam, Stephanie; Zheng, Ming; Fagan, Jeffrey A

    2016-04-26

    Accurate characterization of dispersed-phase nanoparticle properties such as density, size, solvation, and charge is necessary for their utilization in applications such as medicine, energy, and materials. Herein, analytical ultracentrifugation (AUC) is used to quantify bile salt surfactant adsorption on length sorted (7,6) single-wall carbon nanotubes (SWCNTs) as a function of bulk surfactant concentration and in the presence of varying quantities of a monovalent salt-sodium chloride. These measurements provide high precision adsorbed surfactant density values in the literature for only the second SWCNT structure to date and report the quantity of adsorbed surfactant across a broad range of bulk surfactant concentrations utilized in SWCNT dispersion processing. Second, the measurements presented herein unambiguously demonstrate, via AUC, a direct relation between the size of the counterion cloud around a surfactant-stabilized SWCNT and solution ionic strength. The results show that changes in the size of the counterion cloud around surfactant-stabilized SWCNT are attributable to electrostatic phenomenon and not to changes in the quantity of adsorbed surfactant with salt addition. These results provide important reference values for projecting SWCNT dispersion behavior as a function of solution conditions and extend the range of nanoparticle properties measurable via AUC. PMID:27031248

  17. Surfactant compositions

    SciTech Connect

    Novakovic, M.; Abend, P.G.

    1987-09-29

    A surfactant composition is described for subsequent addition to a soap slurring comprising an acyloxy alkane sulfonate salt. The sulfonate salt is present in an amount by weight of about 44 percent of about 56 percent. The polyol is present in an amount by weight of about 2 percent to about 6 percent, and water is present in an amount by weight of 26 to 36 percent. The composition constituting a solid reversible solution at ambient temperature and having a solids content of about 58 to 72 percent, whereby subsequent addition of the surfactant composition to a soap slurry results in formation of a soap/detergent bar having a smooth texture, uniform wear properties and a lack of grittiness.

  18. The dependence of surface tension on surface properties of ionic surfactant solution and the effects of counter-ions therein.

    PubMed

    Wang, Chuangye; Morgner, Harald

    2014-11-14

    In the present paper, we aim to investigate the dependence of surface tension on the surface properties and reveal the counter-ion effects on the adsorption of ionic surfactants on the solution surface. The surface tension, surface excess and surface concentration (defined as the amount of surfactant adsorbed in the surface phase divided by the surface area) of two anionic surfactants, namely dodecyl sulfate sodium and dodecyl sulfate caesium, dissolved in non-aqueous polar solvent formamide have been separately measured at 6 °C through independent experiments. Then, the correlation of surface tension with surface concentration and that of surface tension with surface excess is inspected in detail. It was found that there is a linear relationship between the surface tension and the surface concentration for the pure solutions of each surfactant, but their surface tension and surface excess cannot be correlated linearly. It is striking that the same surface tension-surface concentration linearity holds for two different surfactants, although they have apparently distinct counter-ions. Based on this finding, it is derived that the surface tension is decided by surface concentration of the surface active ions. After analyzing the surface structure, it is concluded that the counter-ions affect the surface tension indirectly through modifying the adsorption amount of the surface active ions in the surface layer.

  19. Influence of Surfactant Bilayers on the Refractive Index Sensitivity and Catalytic Properties of Anisotropic Gold Nanoparticles.

    PubMed

    Martinsson, Erik; Shahjamali, Mohammad M; Large, Nicolas; Zaraee, Negin; Zhou, Yu; Schatz, George C; Mirkin, Chad A; Aili, Daniel

    2016-01-20

    Shape-controlled synthesis of gold nanoparticles generally involves the use of surfactants, typically cetyltrimethylammonium (CTAX, X = Cl(-) , Br(-)), to regulate the nucleation growth process and to obtain colloidally stable nanoparticles. The surfactants adsorb on the nanoparticle surface making further functionalization difficult and therefore limit their use in many applications. Herein, the influence of CTAX on nanoparticle sensitivity to local dielectric environment changes is reported. It is shown, both experimentally and theoretically, that the CTAX bilayer significantly reduces the refractive index (RI) sensitivity of anisotropic gold nanoparticles such as nanocubes and concave nanocubes, nanorods, and nanoprisms. The RI sensitivity can be increased by up to 40% by removing the surfactant layer from nanoparticles immobilized on a solid substrate using oxygen plasma treatment. This increase compensates for the otherwise problematic decrease in RI sensitivity caused by the substrate effect. Moreover, the removal of the surfactants both facilitates nanoparticle biofunctionalization and significantly improves their catalytic properties. The strategy presented herein is a simple yet effective universal method for enhancing the RI sensitivity of CTAX-stabilized gold nanoparticles and increasing their potential as transducers in nanoplasmonic sensors, as well as in catalytic and biomedical applications. PMID:26583756

  20. Remobilizing the Interfaces of Thermocapillary Driven Bubbles Retarded by the Adsorption of a Surfactant Impurity on the Bubble Surface

    NASA Technical Reports Server (NTRS)

    Palaparthi, Ravi; Maldarelli, Charles; Papageorgiou, Dimitri; Singh, Bhim S. (Technical Monitor)

    2000-01-01

    concentrations than the impurity, it adsorbs to the bubble much faster than the impurity when the bubble is formed, and thereby prevents the impurity from adsorbing onto the surface. In addition the rapid kinetic exchange and high bulk concentration maintain a saturated surface with a uniform surface concentrations. This prevents retarding surface tension gradients and keeps the velocity high. In our first report last year, we detailed experimental results which verified the theory of remobilization in ground based experiments in which the steady velocity of rising bubbles was measured in a continuous phase consisting of a glycerol/water mixture containing a polyethylene glycol surfactant C12E6 (CH3(CH2)11(OCH2CH2)6OH). In our report this year, we detail our efforts to describe theoretically the remobilization observed. We construct a model in which a bubble rises steadily by buoyancy in a continuous (Newtonian) viscous fluid containing surfactant with a uniform far field bulk concentration. We account for the effects of inertia as well as viscosity in the flow in the continuous phase caused by the bubble motion (order one Reynolds number), and we assume that the bubble shape remains spherical (viscous and inertial forces are smaller than capillary forces, i e. small Weber and capillary numbers). The surfactant distribution is calculated by solving the mass transfer equations including convection and diffusion in the bulk, and finite kinetic exchange the bulk and the surface. Convective effects dominate diffusive mass transfer in the bulk of the liquid (high Peclet numbers) except in a thin boundary layer near the surface. A finite volume method is used to numerically solve the hydrodynamic and mass transfer equations on a staggered grid which accounts specifically for the thin boundary layer. We present the results of the nondimensional drag as a function of the bulk concentration of surfactant for different rates of kinetic exchange, from which we develop criteria for the

  1. Crystalline surfactant dispersions by radio frequency absorption

    SciTech Connect

    Tedder, S.H.

    1986-03-01

    Recently interest has increased in the use of liquid crystalline surfactant dispersions for enhanced oil recovery. The object of the work described in the report was to develop a method of measuring the electrical properties of colloidal surfactant particles, which control the structure and stability of the surfactant dispersion. A further object was to find how these electrical properties are affected by the method used to mix the components of the dispersion. The results may be useful in solving several practical problems, including the identification of optimally performing liquid crystalline surfactant formulations for oil recovery use. Another possible use is to identify and categorize effects of the method of mixing surfactants on the final product. This information would provide guidelines for field handling of chemical recovery agents. The absorption of radio frequency energy, a process which is mediated by the surface electrical properties of the surfactant particles, was used to measure several electrical parameters of the surfactant mixtures. Two commercial petroleum sulfonate surfactants were tested by the radio frequency absorption method, and a model of their electrical properties was developed and used to fit the data. The strength of the layer of electric charges surrounding the surfactant particles was found to be related to the stability of the solution. 10 refs., 4 figs., 3 tabs.

  2. Surfactant adsorption to soil components and soils.

    PubMed

    Ishiguro, Munehide; Koopal, Luuk K

    2016-05-01

    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 water/air interfaces, the latter gives an impression of surfactant adsorption to a hydrophobic surface and illustrates the importance of the CMC for the adsorption process. Then attention is paid to the most important types of soil particles: humic and fulvic acids, silica, metal oxides and layered aluminosilicates. Information is provided on their structure, surface properties and primary (proton) charge characteristics, which are all important for surfactant binding. Subsequently, the adsorption of different types of surfactants on these individual soil components is discussed in detail, based on mainly experimental results and considering the specific (chemical) and electrostatic interactions, with hydrophobic attraction as an important component of the specific interactions. Adsorption models that can describe the features semi-quantitatively are briefly discussed. In the last part of the paper some trends of surfactant adsorption on soils are briefly discussed together with some complications that may occur and finally the consequences of surfactant adsorption for soil colloidal stability and permeability are considered. When we seek to understand the fate of surfactants in soil and aqueous environments, the hydrophobicity and charge density of the soil or soil particles, must be considered together with the structure, hydrophobicity and charge of the surfactants, because these factors affect the adsorption. The pH and ionic strength are important parameters with respect to the charge density of the particles. As surfactant adsorption influences soil structure and permeability, insight in surfactant adsorption to soil particles is useful for good soil management. PMID

  3. Stabilization of aqueous suspensions serving as the basis for cooling lubricant liquids using nonionogenic surfactants

    SciTech Connect

    Baranova, B.I.; Volkova, M.V.; Belyaeva, N.N.; Lavrov, I.S.; Kopylov, Y.S.

    1983-01-20

    A study of the adsorption of nonionogenic surfactants on the surface of antifriction materials (S-O graphite, molybdenum disulfide, and boron nitride) showed that the formation of saturated adsorption layers occurs at surfactant concentrations close to the critical micelle concentration. The adsorption of all the surfactants studied occurs best on the most hydrophobic surface (the graphite surface). The best stabilizing action of the surfactant is found at surfactant concentrations corresponding to the formation of a saturated adsorption layer when the packing of the surfactant molecules in the adsorption layer is rather dense, which apparently corresponds to the best hydration of the particle surface.

  4. Cationic surfactant adsorption states determined by the dependence of the electrophoretic mobility on dilution

    SciTech Connect

    Chang, C.H.

    1987-01-01

    A dilution method was devised in order to examine the dependence of the mobility of dilute aqueous coal dispersions on concentration. Mobility trends observed on dilution with water and the parent surfactant solution were interpreted in terms of desorption and adsorption of surfactant on coal. The dispersions were also studied by comparing the surface tension of surfactant solutions with the filtrates from a range of coal dispersions. The surfactants used were DTAB (Dodecyltrimethylammonium Bromide), CTAB (Cetyltrimethylammonium Bromide), ATLAS G-271 (N-Soya-N-ethyl morpholinium ethosulfate) and MERPOL-SE, (CH/sub 3/-(CH/sub 2/)/sub 24/-(OCH/sub 2/CH/sub 2/)/sub 8/-OH). The mobility of coal in the presence of cationic surfactant decreased as the dilution ratio increased and reach a constant value. It was also shown that the mobility remained near zero and constant if a non-ionic surfactant was used. On dilution with cationic surfactant solution, the mobility rose to a constant value at high dilution which was more than twice the aqueous asymptote suggesting the separate contribution of reversibility adsorbed surfactant. The structure of surfactant was another effect which controlled the adsorption mechanism. The two major properties of surfactant structure were the hydrophobicity and steric hindrance. The results also implied that hydrophobic tail-adsorbed was the dominant mechanism in contrast to the model which was proposed in earlier studies. Comparison of surface tension between pure surfactant solution and the filtrate from coal/surfactant solution indicated that the surfactants did not all act alike in some cases. Natural surfactant had been desorbed or eluted and in some cases surfactant had been adsorbed.

  5. Volumetric Interpretation of Protein Adsorption: Capacity Scaling with Adsorbate Molecular Weight and Adsorbent Surface Energy

    PubMed Central

    Parhi, Purnendu; Golas, Avantika; Barnthip, Naris; Noh, Hyeran; Vogler, Erwin A.

    2009-01-01

    Silanized-glass-particle adsorbent capacities are extracted from adsorption isotherms of human serum albumin (HSA, 66 kDa), immunoglobulin G (IgG, 160 kDa), fibrinogen (Fib, 341 kDa), and immunoglobulin M (IgM, 1000 kDa) for adsorbent surface energies sampling the observable range of water wettability. Adsorbent capacity expressed as either mass-or-moles per-unit-adsorbent-area increases with protein molecular weight (MW) in a manner that is quantitatively inconsistent with the idea that proteins adsorb as a monolayer at the solution-material interface in any physically-realizable configuration or state of denaturation. Capacity decreases monotonically with increasing adsorbent hydrophilicity to the limit-of-detection (LOD) near τo = 30 dyne/cm (θ~65o) for all protein/surface combinations studied (where τo≡γlvocosθ is the water adhesion tension, γlvo is the interfacial tension of pure-buffer solution, and θ is the buffer advancing contact angle). Experimental evidence thus shows that adsorbent capacity depends on both adsorbent surface energy and adsorbate size. Comparison of theory to experiment implies that proteins do not adsorb onto a two-dimensional (2D) interfacial plane as frequently depicted in the literature but rather partition from solution into a three-dimensional (3D) interphase region that separates the physical surface from bulk solution. This interphase has a finite volume related to the dimensions of hydrated protein in the adsorbed state (defining “layer” thickness). The interphase can be comprised of a number of adsorbed-protein layers depending on the solution concentration in which adsorbent is immersed, molecular volume of the adsorbing protein (proportional to MW), and adsorbent hydrophilicity. Multilayer adsorption accounts for adsorbent capacity over-and-above monolayer and is inconsistent with the idea that protein adsorbs to surfaces primarily through protein/surface interactions because proteins within second (or higher

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  7. Surface forces between titanium dioxide surfaces in the presence of cationic surfactant as a function of surfactant concentration, electrolyte concentration, and pH.

    PubMed

    Walsh, Rick B; Wu, Bo; Howard, Shaun C; Craig, Vincent S J

    2014-03-18

    Titanium dioxide (titania) surfaces produced by atomic layer deposition (ALD) are suitable for surfactant adsorption and surface force measurements. Adsorption isotherms for cetyltrimethylammonium bromide (CTAB) on ALD titanium dioxide surfaces were measured using optical reflectometry (OR), and surface force measurements between ALD titanium dioxide surfaces in aqueous CTAB solutions were measured using the colloid probe technique at different pH and electrolyte concentrations. Measurements were performed at a range of concentrations below and above the common intersection point (CIP) where adsorption is dominated by electrostatic and hydrophobic interactions, respectively. An examination of surfactant adsorption above and below the isoelectric point (IEP) was performed. Interestingly, significant levels of adsorption were observed below the IEP where the electrostatic interactions are unfavorable. The adsorption results are used to interpret the force data, which is dependent upon the amount of surfactant adsorbed and the electrolyte concentration and pH. The surface force data is compared to DLVO theory. Poor fits are obtained when Lifshitz theory is used to describe the dispersion forces. However, all of the data are fit well with a dispersion force of reduced magnitude. The kinetics of adsorption was measured and reveals very slow adsorption kinetics below the critical micelle concentration as a result of the monomer-by-monomer formation of aggregates on the surface.

  8. Field experiment of lignosulfonate preflushing for surfactant adsorption reduction

    SciTech Connect

    Hong, S.A. ); Bae, J.H. )

    1990-11-01

    Lignosulfonate was field tested as a sacrificial adsorbate in conjunction with the ongoing Glenn Pool surfactant flood expansion project. A 2 wt% lignosulfonate solution was injected for 10 days as part of the preflush in this project. Results of the analyses of two observation well samples are interpreted for the effect of lignosulfonate on sulfonate absorption and process performance. Even though the evidence was ambiguous, the authors conclude that the low-cost lignosulfonate preflushing was beneficial to surfactant flooding.

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

    PubMed

    Taeusch, H William; Bernardino de la Serna, Jorge; Perez-Gil, Jesus; Alonso, Coralie; Zasadzinski, Joseph A

    2005-09-01

    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 increases in pi did not occur when surfactants were applied to subphases containing serum. Components of serum are surface active and adsorb reversibly to the interface increasing pi up to a concentration-dependent saturation value, pi(max). When surfactants were applied to subphases containing serum, the increase in pi was significantly slowed or eliminated. Therefore, serum at the interface presents a barrier to surfactant adsorption. Addition of either hyaluronan (normally found in alveolar fluid) or polyethylene glycol to subphases containing serum reversed inhibition by restoring the rate of surfactant adsorption to that of the clean interface, thereby allowing surfactant to overcome the serum-induced barrier to adsorption.

  10. Modeling adsorption: Investigating adsorbate and adsorbent properties

    NASA Astrophysics Data System (ADS)

    Webster, Charles Edwin

    1999-12-01

    Surface catalyzed reactions play a major role in current chemical production technology. Currently, 90% of all chemicals are produced by heterogeneously catalyzed reactions. Most of these catalyzed reactions involve adsorption, concentrating the substrate(s) (the adsorbate) on the surface of the solid (the adsorbent). Pore volumes, accessible surface areas, and the thermodynamics of adsorption are essential in the understanding of solid surface characteristics fundamental to catalyst and adsorbent screening and selection. Molecular properties such as molecular volumes and projected molecular areas are needed in order to convert moles adsorbed to surface volumes and areas. Generally, these molecular properties have been estimated from bulk properties, but many assumptions are required. As a result, different literature values are employed for these essential molecular properties. Calculated molar volumes and excluded molecular areas are determined and tabulated for a variety of molecules. Molecular dimensions of molecules are important in the understanding of molecular exclusion as well as size and shape selectivity, diffusion, and adsorbent selection. Molecular dimensions can also be used in the determination of the effective catalytic pore size of a catalyst. Adsorption isotherms, on zeolites, (crystalline mineral oxides) and amorphous solids, can be analyzed with the Multiple Equilibrium Analysis (MEA) description of adsorption. The MEA produces equilibrium constants (Ki), capacities (ni), and thermodynamic parameters (enthalpies, ΔHi, and entropies, ΔSi) of adsorption for each process. Pore volumes and accessible surface areas are calculated from the process capacities. Adsorption isotherms can also be predicted for existing and new adsorbate-adsorbent systems with the MEA. The results show that MEA has the potential of becoming a standard characterization method for microporous solids that will lead to an increased understanding of their behavior in gas

  11. The salivary mucin MUC5B and lactoperoxidase can be used for layer-by-layer film formation.

    PubMed

    Lindh, Liselott; Svendsen, Ida E; Svensson, Olof; Cárdenas, Marité; Arnebrant, Thomas

    2007-06-01

    In situ ellipsometry was used to study layer-by-layer film formation on hydrophilic and hydrophobized silica surfaces by alternating sequential adsorption of human mucin MUC5B and cationic proteins lysozyme, lactoferrin, lactoperoxidase or histatin 5, respectively. The stability of the multilayers was investigated by addition of sodium dodecyl sulfate solution (SDS). Atomic force microscopy was employed to investigate morphological structures on the surfaces during the layer-by-layer film build-up. It was clearly shown that, on both hydrophilic and hydrophobized silica, only MUC5B and lactoperoxidase showed the ability for multilayer formation, resulting in an approximately linear increase in adsorbed amount and film thickness with each deposition cycle. The net increase in amounts per cycle was larger on the hydrophilic silica. Further, MUC5B needs to be adsorbed first on the hydrophilic substrates to obtain this fast build-up behavior. Generally, addition of SDS solution showed that a large fraction of the adsorbed film could be desorbed. However, films on the hydrophobized silica were more resistant to surfactant elution. In conclusion, MUC5B-cationic protein multilayers can be formed on hydrophilic and hydrophobized silica, depending on the choice of the cationic protein as well as in which order the build-up is started on hydrophilic silica. Additionally, SDS disrupts the layer-by-layer film formed by MUC5B and lactoperoxidase.

  12. Charge transfer from an adsorbed ruthenium-based photosensitizer through an ultra-thin aluminium oxide layer and into a metallic substrate

    SciTech Connect

    Gibson, Andrew J.; Temperton, Robert H.; Handrup, Karsten; Weston, Matthew; Mayor, Louise C.; O’Shea, James N.

    2014-06-21

    The interaction of the dye molecule N3 (cis-bis(isothiocyanato)bis(2,2-bipyridyl-4,4′-dicarbo-xylato) -ruthenium(II)) with the ultra-thin oxide layer on a AlNi(110) substrate, has been studied using synchrotron radiation based photoelectron spectroscopy, resonant photoemission spectroscopy, and near edge X-ray absorption fine structure spectroscopy. Calibrated X-ray absorption and valence band spectra of the monolayer and multilayer coverages reveal that charge transfer is possible from the molecule to the AlNi(110) substrate via tunnelling through the ultra-thin oxide layer and into the conduction band edge of the substrate. This charge transfer mechanism is possible from the LUMO+2 and 3 in the excited state but not from the LUMO, therefore enabling core-hole clock analysis, which gives an upper limit of 6.0 ± 2.5 fs for the transfer time. This indicates that ultra-thin oxide layers are a viable material for use in dye-sensitized solar cells, which may lead to reduced recombination effects and improved efficiencies of future devices.

  13. Surfactants identified in synovial fluid and their ability to act as boundary lubricants.

    PubMed Central

    Hills, B A; Butler, B D

    1984-01-01

    Thin-layer chromatography has been used to identify phospholipids extracted from canine synovial fluid, the major component (45%) being phosphatidyl choline (PC). The extracts and their components have been shown to be surface active in reducing the surface tension of water and to be readily adsorbed to hydrophilic solids, whose surfaces then become hydrophobic. These adsorbed monolayers of synovial surfactant were then found to be excellent boundary lubricants in vitro, reducing the coefficient of kinetic friction (mu) in the dry state and under physiological loading by up to 97% for extracts and 99% for PC alone, reaching mu = 0.01. Surface-active phospholipid is put forward as the possible active ingredient in joint lubrication and shown to be consistent with previous biochemical studies to elucidate its identity. The model essentially follows the classical Hardy model for boundary lubrication imparted by surfactants. It is discussed in relation to a new approach in providing artificial lubrication and facilitating tissue release in patients with arthritis. PMID:6476922

  14. Adsorption of mixed cationic-nonionic surfactant and its effect on bentonite structure.

    PubMed

    Zhang, Yaxin; Zhao, Yan; Zhu, Yong; Wu, Huayong; Wang, Hongtao; Lu, Wenjing

    2012-01-01

    The adsorption of cationic-nonionic mixed surfactant onto bentonite and its effect on bentonite structure were investigated. The objective was to improve the understanding of surfactant behavior on clay mineral for its possible use in remediation technologies of soil and groundwater contaminated by toxic organic compounds. The cationic surfactant used was hexadecylpyridinium bromide (HDPB), and the nonionic surfactant was Triton X-100 (TX100). Adsorption of TX100 was enhanced significantly by the addition of HDPB, but this enhancement decreased with an increase in the fraction of the cationic surfactant. Part of HDPB was replaced by TX100 which decreased the adsorption of HDPB. However, the total adsorbed amount of the mixed surfactant was still increased substantially, indicating the synergistic effect between the cationic and nonionic surfactants. The surfactant-modified bentonite was characterized by Brunauer-Emmett-Teller specific surface area measurement, Fourier transform infrared spectroscopy, and thermogravimetric-derivative thermogravimetric/differential thermal analyses. Surfactant intercalation was found to decrease the bentonite specific surface area, pore volume, and surface roughness and irregularities, as calculated by nitrogen adsorption-desorption isotherms. The co-adsorption of the cationic and nonionic surfactants increased the ordering conformation of the adsorbed surfactants on bentonite, but decreased the thermal stability of the organobentonite system.

  15. Thermally cleavable surfactants

    DOEpatents

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

    2009-11-24

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

  16. Thermally cleavable surfactants

    DOEpatents

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

    2009-09-29

    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.

  17. Thermally cleavable surfactants

    DOEpatents

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

    2006-04-04

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

  18. Anionic surfactant - Biogenic amine interactions: The role of surfactant headgroup geometry.

    PubMed

    Penfold, Jeffrey; Thomas, Robert K; Li, Peixun

    2016-03-15

    Oligoamines and biogenic amines (naturally occurring oligoamines) are small flexible polycations. They interact strongly with anionic surfactants such as sodium dodecyl sulfate, SDS. This results in enhanced adsorption and the formation of layered structures and the formation of layered structures at the air-water interface which depends on surfactant concentration and solution pH. The effect of changing the surfactant headgroup geometry on that interaction and subsequent adsorption is reported here. Neutron reflectivity, NR, results for the surface adsorption of the anionic surfactant sodium diethylene glycol monododecyl ether sulfate, SLES, with the biogenic amine, spermine, are presented, and contrasted with previous data for SDS/spermine mixtures. The enhancement in the adsorption of the surfactant at the air-water interface where monolayer adsorption occurs is similar for both surfactants. However the regions of surfactant concentration and solution pH where surface multilayer adsorption occurs is less extensive for the SLES/spermine mixtures, and occurs only at low pH. The results show how changing the headgroup geometry by the introduction of the ethylene oxide linker group between the alkyl chain and sulfate headgroup modifies the polyamine - surfactant interaction. The increased steric constraint from the polyethylene oxide group disrupts the conditions for surface multilayer formation at the higher pH values. This has important consequences for applications where the modification or manipulation of the surface properties are required. PMID:26724704

  19. Interfacial aggregation of a nonionic surfactant: Effect on the stability of silica suspensions

    SciTech Connect

    Giordano-Palmino, F.; Denoyel, R.; Rouquerol, J. . Centre de thermodynamique et Microcalorimetrie)

    1994-06-01

    Nonionic surfactants are in widespread use in technological applications such as flotation, detergency, suspension stabilization (paints, ceramic preparation, pharmaceuticals, cosmetics), and enhanced oil recovery. The adsorption of the nonionic surfactant TX 100 in two silica suspensions (Ludox HS40 and Syton W30) has been studied with the aim of relating the structure of the adsorbed layer to the stability of the suspension. First, a thermodynamic study based on the determination of adsorption isotherms and displacement enthalpies as a function of pH and solid/liquid ratio was carried out and lead to the conclusion that such a surfactant forms micelle-like aggregates on the silica surface. Then, a stability study based on visual observation, turbidimetry, and particle size determination (by photon correlation spectroscopy) was performed in order to determine the TX 100 concentration range in which flocculation occurs. Considering that the surface is covered with micelle-like aggregates in the flocculation range and that the [zeta]-potential (determined by microelectrophoresis) has varied only slightly at the onset of flocculation, it is concluded that the flocculation mechanism is a bridging of particles by surface micelles. This bridging of particles by aggregates similar in size and shape could be an explanation of the presence, in such systems, of optimum flocculation at half surface coverage.

  20. Extended delivery of an anionic drug by contact lens loaded with a cationic surfactant.

    PubMed

    Bengani, Lokendrakumar C; Chauhan, Anuj

    2013-04-01

    Drug eluding contact lenses can be very effective vehicles for ophthalmic drug delivery, but are incapable of releasing drug for more than a few hours. We propose to optimize the interactions of the polymer matrix of the contact lens with the hydrophobic tails of ionic surfactants to adsorb the surfactant molecules on the polymer with high packing and thus create a high surface charge. Ionic drugs can then adsorb on the charged surfactant coated surfaces with high affinity to reduce the transport rates, leading to extended release. Specifically, we show control release of an anionic drug dexamethasone 21-disodium phosphate from poly-hydroxyethyl methacrylate (p-HEMA) contact lenses by utilizing cationic surfactant (cetalkonium chloride). The partition coefficient of the drug increase exponentially with surfactant loading in the gel in at least qualitative agreement with the Debye-Hückel theory. The drug adsorbs on the surfactant covered polymer, and can also diffuse along the surface with diffusivity lower than that for the free drug, leading to a reduction in the effective diffusivity, which is the weighted combination of the free and surface diffusivities. The addition of surfactant did not impact transparency of lenses, and had additional benefits of increase in wettability and significant reduction in protein absorption. With a surfactant loading of about 10%, the drug release duration was increased from about 2 h to 50 h in 1-day ACUVUE(®) contact lenses, proving the viability of using surfactant for increasing drug release durations.

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

    PubMed

    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. PMID:27250319

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  4. Structure and properties of water film adsorbed on mica surfaces.

    PubMed

    Zhao, Gutian; Tan, Qiyan; Xiang, Li; Cai, Di; Zeng, Hongbo; Yi, Hong; Ni, Zhonghua; Chen, Yunfei

    2015-09-14

    The structure profiles and physical properties of the adsorbed water film on a mica surface under conditions with different degrees of relative humidity are investigated by a surface force apparatus. The first layer of the adsorbed water film shows ice-like properties, including a lattice constant similar with ice crystal, a high bearing capacity that can support normal pressure as high as 4 MPa, a creep behavior under the action of even a small normal load, and a character of hydrogen bond. Adjacent to the first layer of the adsorbed water film, the water molecules in the outer layer are liquid-like that can flow freely under the action of external loads. Experimental results demonstrate that the adsorbed water layer makes the mica surface change from hydrophilic to weak hydrophobic. The weak hydrophobic surface may induce the latter adsorbed water molecules to form water islands on a mica sheet. PMID:26374054

  5. Structure and properties of water film adsorbed on mica surfaces.

    PubMed

    Zhao, Gutian; Tan, Qiyan; Xiang, Li; Cai, Di; Zeng, Hongbo; Yi, Hong; Ni, Zhonghua; Chen, Yunfei

    2015-09-14

    The structure profiles and physical properties of the adsorbed water film on a mica surface under conditions with different degrees of relative humidity are investigated by a surface force apparatus. The first layer of the adsorbed water film shows ice-like properties, including a lattice constant similar with ice crystal, a high bearing capacity that can support normal pressure as high as 4 MPa, a creep behavior under the action of even a small normal load, and a character of hydrogen bond. Adjacent to the first layer of the adsorbed water film, the water molecules in the outer layer are liquid-like that can flow freely under the action of external loads. Experimental results demonstrate that the adsorbed water layer makes the mica surface change from hydrophilic to weak hydrophobic. The weak hydrophobic surface may induce the latter adsorbed water molecules to form water islands on a mica sheet.

  6. Poly(ethylene oxide) surfactant polymers

    PubMed Central

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

    2005-01-01

    We report on a series of structurally well-defined surfactant polymers that undergo surface-induced self-assembly on hydrophobic biomaterial surfaces. The surfactant polymers consist of a poly(vinyl amine) backbone with poly(ethylene oxide) and hexanal pendant groups. The poly(vinyl amine) (PVAm) was synthesized by hydrolysis of poly(N-vinyl formamide) following free radical polymerization of N-vinyl formamide. Hexanal and aldehyde-terminated poly (ethyleneoxide) (PEO) were simultaneously attached to PVAm via reductive amination. Surfactant polymers with different PEO : hexanal ratios and hydrophilic/hydrophobic balances were prepared, and characterized by FT-IR, 1H-NMR and XPS spectroscopies. Surface active properties at the air/water interface were determined by surface tension measurements. Surface activity at a solid surface/water interface was demonstrated by atomic force microscopy, showing epitaxially molecular alignment for surfactant polymers adsorbed on highly oriented pyrolytic graphite. The surfactant polymers described in this report can be adapted for simple non-covalent surface modification of biomaterials and hydrophobic surfaces to provide highly hydrated interfaces. PMID:15027845

  7. The relationship between the adhesion work, the wettability and composition of the surface layer in the systems polymer/aqueous solution of anionic surfactants and alcohol mixtures

    NASA Astrophysics Data System (ADS)

    Zdziennicka, Anna; Jańczuk, Bronisław

    2010-11-01

    Measurements of advancing contact angle ( θ) were carried out on polytetrafluoroethylene (PTFE) and polymethylmethacrylate (PMMA) for aqueous solution of sodium dodecyl sulfate (SDDS) mixtures with methanol, ethanol and propanol in the range of SDDS concentration from 10 -5 to 10 -2 M, and for sodium hexadecyl sulfonate (SHS) with the same alcohols at the SHS concentration ranging from 10 -5 to 8 × 10 -4 M at 293 K. The concentration of methanol, ethanol and propanol used for measurements varied from 0 to 21.1, 11.97 and 6.67 M, respectively. On the basis of the contact angles the critical surface tension of PTFE and PMMA wetting was determined by using for this purpose the relationship between the adhesion and the surface tension and cos θ and surface tension both at constant alcohol and surfactant concentration, respectively. The obtained contact angles were also used in the Young Dupre' equation for calculations of the adhesion work of aqueous solution of mixtures of anionic surfactants and short chain alcohols to PTFE and PMMA surface. The adhesion work calculated in this way was compared to that of the particular components of aqueous solution to these surfaces determined on the basis of the surface tension components and parameters of the surface tension of the surface active agents, water, PTFE and PMMA from van Oss et al. equation. The calculated adhesion work was discussed in the light of the concentration of surface active agents at polymer-water and water-air interface determined from Lucassen-Reynders, Gibbs and Guggenheim-Adam equations.

  8. Polymerizable gemini surfactants at solid/solution interfaces: adsorption and polymerization on melamine formaldehyde particles and capsule fabrication.

    PubMed

    Sakai, Kenichi; Izumi, Keiko; Sakai, Hideki; Abe, Masahiko

    2010-03-15

    Organic capsules have been fabricated via three steps, by using the polymerizable gemini surfactant (1,2-bis(dimethyl(11-methacryloyloxy)undecylammonio) hexane dibromide, PC11-6-11) as a single wall component. In the first fabrication step, the surfactant spontaneously adsorbs on acid-dissolvable melamine formaldehyde (MF) particles in aqueous media. The adsorption isotherm data reveal that the adsorbed amount of PC11-6-11 (per chain) is greater than that of the corresponding monomeric surfactant ((11-methacryloyloxy)undecyltrimethylammonium bromide, PC11), resulting from the greater intermolecular association of PC11-6-11 at the solid/solution interface. The closely packed adsorbed layer of PC11-6-11 provides an opportunity to give a polymer thin film, as a result of in situ photo-polymerization on MF particles (in the second fabrication step) and subsequent acid dissolution of the core MF particles (in the third fabrication step). The dynamic light scattering (DLS) measurements have shown that the apparent hydrodynamic diameter of PC11-6-11 capsules is reversibly changed in response to a change in ionic strength: the increased background electrolyte concentration results in deswelling of the capsules, and vice versa. It seems likely that this swelling/deswelling behavior is primarily driven by the electrostatic interaction between quaternary ammonium groups within the polymerized film. We have also studied the capture and release capabilities of glucose into/from the capsule core and found that (i) glucose is encapsulated into the capsule core at high electrolyte concentrations and (ii) the glucose molecules encapsulated into the core are gradually released when the outer electrolyte solution is replaced by pure water. We believe, therefore, that the PC11-6-11 capsules fabricated here are useful as stimulus-responsive smart vehicles.

  9. Surfactant-enhanced remediation of organic contaminated soil and water.

    PubMed

    Paria, Santanu

    2008-04-21

    Surfactant based remediation technologies for organic contaminated soil and water (groundwater or surface water) is of increasing importance recently. Surfactants are used to dramatically expedite the process, which in turn, may reduce the treatment time of a site compared to use of water alone. In fact, among the various available remediation technologies for organic contaminated sites, surfactant based process is one of the most innovative technologies. To enhance the application of surfactant based technologies for remediation of organic contaminated sites, it is very important to have a better understanding of the mechanisms involved in this process. This paper will provide an overview of the recent developments in the area of surfactant enhanced soil and groundwater remediation processes, focusing on (i) surfactant adsorption on soil, (ii) micellar solubilization of organic hydrocarbons, (iii) supersolubilization, (iv) density modified displacement, (v) degradation of organic hydrocarbon in presence surfactants, (vi) partitioning of surfactants onto soil and liquid organic phase, (vii) partitioning of contaminants onto soil, and (viii) removal of organics from soil in presence of surfactants. Surfactant adsorption on soil and/or sediment is an important step in this process as it results in surfactant loss reduced the availability of the surfactants for solubilization. At the same time, adsorbed surfactants will retained in the soil matrix, and may create other environmental problem. The biosurfactants are become promising in this application due to their environmentally friendly nature, nontoxic, low adsorption on to soil, and good solubilization efficiency. Effects of different parameters like the effect of electrolyte, pH, soil mineral and organic content, soil composition etc. on surfactant adsorption are discussed here. Micellar solubilization is also an important step for removal of organic contaminants from the soil matrix, especially for low aqueous

  10. Pulmonary surfactants and their role in pathophysiology of lung disorders.

    PubMed

    Akella, Aparna; Deshpande, Shripad B

    2013-01-01

    Surfactant is an agent that decreases the surface tension between two media. The surface tension between gaseous-aqueous interphase in the lungs is decreased by the presence of a thin layer of fluid known as pulmonary surfactant. The pulmonary surfactant is produced by the alveolar type-II (AT-II) cells of the lungs. It is essential for efficient exchange of gases and for maintaining the structural integrity of alveoli. Surfactant is a secretory product, composed of lipids and proteins. Phosphatidylcholine and phosphatidylglycerol are the major lipid constituents and SP-A, SP-B, SP-C, SP-D are four types of surfactant associated proteins. The lipid and protein components are synthesized separately and are packaged into the lamellar bodies in the AT-II cells. Lamellar bodies are the main organelle for the synthesis and metabolism of surfactants. The synthesis, secretion and recycling of the surfactant lipids and proteins is regulated by complex genetic and metabolic mechanisms. The lipid-protein interaction is very important for the structural organization of surfactant monolayer and its functioning. Alterations in surfactant homeostasis or biophysical properties can result in surfactant insufficiency which may be responsible for diseases like respiratory distress syndrome, lung proteinosis, interstitial lung diseases and chronic lung diseases. The biochemical, physiological, developmental and clinical aspects of pulmonary surfactant are presented in this article to understand the pathophysiological mechanisms of these diseases.

  11. Turbulent drag reduction in nonionic surfactant solutions

    NASA Astrophysics Data System (ADS)

    Tamano, Shinji; Itoh, Motoyuki; Kato, Katsuo; Yokota, Kazuhiko

    2010-05-01

    There are only a few studies on the drag-reducing effect of nonionic surfactant solutions which are nontoxic and biodegradable, while many investigations of cationic surfactant solutions have been performed so far. First, the drag-reducing effects of a nonionic surfactant (AROMOX), which mainly consisted of oleyldimethylamineoxide, was investigated by measuring the pressure drop in the pipe flow at solvent Reynolds numbers Re between 1000 and 60 000. Second, we investigated the drag-reducing effect of a nonionic surfactant on the turbulent boundary layer at momentum-thickness Reynolds numbers Reθ from 443 to 814 using two-component laser-Doppler velocimetry and particle image velocimetry systems. At the temperature of nonionic surfactant solutions, T =25 °C, the maximum drag reduction ratio for AROMOX 500 ppm was about 50%, in the boundary layer flow, although the drag reduction ratio was larger than 60% in pipe flow. Turbulence statistics and structures for AROMOX 500 ppm showed the behavior of typical drag-reducing flow such as suppression of turbulence and modification of near-wall vortices, but they were different from those of drag-reducing cationic surfactant solutions, in which bilayered structures of the fluctuating velocity vectors were observed in high activity.

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

    USGS Publications Warehouse

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

    1995-01-01

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

  13. Surfactant role of Ag atoms in the growth of Si layers on Si(111)√3×√3-Ag substrates

    SciTech Connect

    Yamagami, Tsuyoshi; Sone, Junki; Nakatsuji, Kan; Hirayama, Hiroyuki

    2014-10-13

    The growth of Si layers on Si(111)√3×√3-Ag substrates was studied for coverages of up to a few mono-layers. Atomically flat islands were observed to nucleate in the growth at 570 K. The top surfaces of the islands were covered in Ag atoms and exhibited a √3×√3 reconstruction with the same surface state dispersions as Si(111)√3×√3-Ag substrates. These results indicate that the Ag atoms on the substrate always hop up to the top of the Si layers.

  14. Surfactant Two-Dimensional Self-Assembly under Confinement

    SciTech Connect

    Sushko, Maria L.; Liu, Jun

    2011-03-28

    Confinement-induced structural rearrangements in supported self-assembled surfactant layers in aqueous salt solutions are investigated using classical Density Functional Theory. The systematic study of the influence of the nature of electrolyte revealed that 2:1 electrolyte stabilizes the hemicylindrical configuration of ionic surfactant layers, while a confinement-induced transition to a tilted monolayer configuration was found in symmetric 1:1 and 2:2 electrolytes. On the basis of this study we formulate a general model for the energetics of structural rearrangements in supported surfactant layers.

  15. Cu sbnd Al sbnd Fe layered double hydroxides with CO32- and anionic surfactants with different alkyl chains in the interlayer

    NASA Astrophysics Data System (ADS)

    Trujillano, Raquel; Holgado, María Jesús; González, José Luis; Rives, Vicente

    2005-08-01

    Layered double hydroxides (LDHs), with the hydrotalcite-like structure containing Cu(II), Al(III) and Fe(III) in the layers, and different alkyl sulfonates in the interlayer, have been prepared and characterized by powder X-ray diffraction, FT-IR spectroscopy, differential thermal analysis and thermogravimetric analysis. Pure crystalline phases have been obtained in all cases. Upon heating, combustion of the organic chain takes place at lower temperature than the corresponding sodium salts.

  16. Foam stabilisation using surfactant exfoliated graphene.

    PubMed

    Sham, Alison Y W; Notley, Shannon M

    2016-05-01

    Liquid-air foams have been stabilised using a suspension of graphene particles at very low particle loadings. The suspension was prepared through the liquid phase exfoliation of graphite in the presence of the non-ionic tri-block surfactant, Pluronic® F108. The graphene particles possess an extremely high aspect ratio, with lateral dimensions of between 0.1 and 1.3 μm as evidenced by TEM imaging. The particles were shown to exhibit a number of other properties known to favour stabilisation of foam structures. Particle surface activity was confirmed through surface tension measurements, suggesting the particles favour adsorption at the air-water interface. The evolution of bubble size distributions over time indicated the presence of particles yielded improvements to foam stability due to a reduction in disproportionation. Foam stability measurements showed a non-linear relationship between foam half-life and graphene concentration, indicative of the rate at which particles adsorb at bubble surfaces. The wettability of the graphene particles was altered upon addition of alkali metal chlorides, with the stability of the foams being enhanced according to the series Na(+)>Li(+)>K(+)>Cs(+). This effect is indicative of the relative hydration capacity of each salt with respect to the surfactant, which is adsorbed along the graphene plane as a result of the exfoliation process. Thus, surfactant exfoliated graphene particles exhibit a number of different features that demonstrate efficient application of high-aspect ratio particles in the customisation and enhancement of foams.

  17. Molecular Adsorber Coating

    NASA Technical Reports Server (NTRS)

    Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

    2011-01-01

    A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and refined, and a procedure for spray application was developed. Samples were spray-coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

  18. Layer-by-layer assembly of thin films containing exfoliated pristine graphene nanosheets and polyethyleneimine.

    PubMed

    Sham, Alison Y W; Notley, Shannon M

    2014-03-11

    A method for the modification of surface properties through the deposition of stabilized graphene nanosheets is described. Here, the thickness of the film is controlled through the use of the layer-by-layer technique, where the sequential adsorption of the cationic polyethyleneimine (PEI) is followed by the adsorption of anionic graphene sheets modified with layers of polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) surfactants. The graphene particles were prepared using the surfactant-assisted liquid-phase exfoliation technique, with the low residual negative charge arising from edge defects. The buildup of the multilayer assembly through electrostatic interactions was strongly influenced by the solution conditions, including pH, ionic strength, and ionic species. Thereby, not only could the thickness of the film be tailored through the choice of the number of bilayers deposited but the viscoelastic properties of the film could also be modified by changing solution conditions at which the different species were deposited. The quartz crystal microbalance was used to measure the mass of graphene and polyelectrolyte immobilized at the interface as well as to probe the energy dissipated in the adsorbed layer.

  19. High-efficiency exfoliation of layered materials into 2D nanosheets in switchable CO2/Surfactant/H2O system

    NASA Astrophysics Data System (ADS)

    Wang, Nan; Xu, Qun; Xu, Shanshan; Qi, Yuhang; Chen, Meng; Li, Hongxiang; Han, Buxing

    2015-11-01

    Layered materials present attractive and important properties due to their two-dimensional (2D) structure, allowing potential applications including electronics, optoelectronics, and catalysis. However, fully exploiting the outstanding properties will require a method for their efficient exfoliation. Here we present that a series of layered materials can be successfully exfoliated into single- and few-layer nanosheets using the driving forces coming from the phase inversion, i.e., from micelles to reverse micelles in the emulsion microenvironment built by supercritical carbon dioxide (SC CO2). The effect of variable experimental parameters including CO2 pressure, ethanol/water ratio, and initial concentration of bulk materials on the exfoliation yield have been investigated. Moreover, we demonstrate that the exfoliated 2D nanosheets have their worthwhile applications, for example, graphene can be used to prepare conductive paper, MoS2 can be used as fluorescent label to perform cellular labelling, and BN can effectively reinforce polymers leading to the promising mechanical properties.

  20. Spinel type CoFe oxide porous nanosheets as magnetic adsorbents with fast removal ability and facile separation.

    PubMed

    Ge, X; Gu, C D; Wang, X L; Tu, J P

    2015-09-15

    Adsorption is often time consuming due to slow diffusion kinetic. Sizing he adsorbent down might help to accelerate adsorption. For CoFe spinel oxide, a magnetically separable adsorbent, the preparation of nanosheets faces many challenges including phase separation, grain growth and difficulty in preparing two-dimensional materials. In this work, we prepared porous CoFe oxide nanosheet with chemical formula of Co2.698Fe0.302O4 through topochemical transformation of a CoFe precursor, which has a layered double hydroxide (LDH) analogue structure and a large interlayer spacing. The LDH precursor was synthesized from a cheap deep eutectic solvent (DES) system. The calcined Co2.698Fe0.302O4 has small grain size (10-20nm), nanosheet morphology, and porous structure, which contribute to a large specific surface area of 79.5m(2)g(-1). The Co2.698Fe0.302O4 nanosheets show fast removal ability and good adsorption capacity for both organic waste (305mgg(-1) in 5min for Congo red) and toxic heavy metal ion (5.27mgg(-1) in 30min for Cr (VI)). Furthermore, the Co2.698Fe0.302O4 can be separated magnetically. Considering the precursor can be prepared through a fast, simple, surfactant-free and high-yield synthetic strategy, this work should have practical significance in fabricating adsorbents.

  1. [Study of novel artificial lung surfactants incorporating partially fluorinated amphiphiles].

    PubMed

    Nakahara, Hiromichi

    2012-01-01

    Lung surfactants (LS), a complex of ∼90 wt% lipids (mainly dipalmitoylphosphatidylcholine or DPPC) and ∼10 wt% surfactant proteins (SP-A, -B, -C, and -D), adsorb to an air-alveolar fluid interface and then lower its surface tension down to near zero during expiration. Intratracheal instillation of exogenous LS preparations can effectively compensate for surfactant deficiency in premature infants with respiratory distress syndrome (RDS). Surfacten® (Mitsubishi Tanabe Pharma Corporation, Osaka, Japan), a modified bovine lung extract and an effective surfactant replacement in treatment for RDS patients, is supplemented with DPPC, palmitic acid, and tripalmitin. For the premature infants suffering from RDS, instillation of Surfacten® leads to a dramatic improvement in lung function and compliance. Herein, the author reviews potential use of newly designed preparations containing a mimicking peptide of SP-B and also introduces the current research on the preparations incorporated with partially fluorinated amphiphiles to improve their efficacy.

  2. Tuning of nanoparticle-surfactant interactions in aqueous system

    NASA Astrophysics Data System (ADS)

    Kumar, Sugam; Aswal, V. K.

    2011-01-01

    The interaction of charged (anionic) silica nanoparticles with ionic and nonionic surfactants has been studied using small-angle neutron scattering (SANS). The surfactants used are anionic sodium dodecyl sulfate (SDS), cationic dodecyltrimethyl ammonium bromide (DTAB) and nonionic decaoxyethylene n-dodecylether (C12E10). The measurements are carried out at fixed concentration (1 wt%) of silica nanoparticles and with surfactant concentration varied in the range 0-2 wt%. It is found that there is no direct interaction between the nanoparticles and the surfactant (SDS) when they both are similarly charged. Both the silica nanoparticles and micelles coexist individually with no significant change in the structure of the micelles with respect to that in the pure surfactant solution. On the other hand, the presence of oppositely charged surfactant (DTAB) leads to the aggregation of silica nanoparticles even with very low surfactant concentration. The aggregation of silica nanoparticles is characterized by fractal structure and its fractal dimension remains constant with the increase in the surfactant concentration. In the case of nonionic surfactant, it interacts with the individual silica nanoparticles. The interaction is examined using two models: one that considers the surfactant layer coating on silica nanoparticles and a second one where the surface of the nanoparticles is decorated by the micelles. Contrast variation SANS measurements confirm the uniform decoration of nonionic micelles on the nanoparticles.

  3. Using specialized adsorbents for remediation

    SciTech Connect

    Hochmuth, D.P.; Grant, A.

    1995-11-01

    This paper describes two remediation case studies in which specialized adsorbents were used. In one case, the adsorbents were used to treat effluent from a soil vapor extraction system. In the other case, the adsorbents were used to treat air from a groundwater air stripper. The specialized adsorbents effectively removed volatile organic compounds from each air stream.

  4. Controlled Uniform Coating from the Interplay of Marangoni Flows and Surface-Adsorbed Macromolecules.

    PubMed

    Kim, Hyoungsoo; Boulogne, François; Um, Eujin; Jacobi, Ian; Button, Ernie; Stone, Howard A

    2016-03-25

    Surface coatings and patterning technologies are essential for various physicochemical applications. In this Letter, we describe key parameters to achieve uniform particle coatings from binary solutions. First, multiple sequential Marangoni flows, set by solute and surfactant simultaneously, prevent nonuniform particle distributions and continuously mix suspended materials during droplet evaporation. Second, we show the importance of particle-surface interactions that can be established by surface-adsorbed macromolecules. To achieve a uniform deposit in a binary mixture, a small concentration of surfactant and surface-adsorbed polymer (0.05 wt% each) is sufficient, which offers a new physicochemical avenue for control of coatings.

  5. Simultaneous removal of PAHs and metal contaminants from water using magnetic nanoparticle adsorbents.

    PubMed

    Huang, Yuxiong; Fulton, Aaron N; Keller, Arturo A

    2016-11-15

    Many industrial wastewaters are contaminated with both heavy metal ions and organic compounds, posing a major threat to public health and the environment. In this study, magnetic nanoparticle adsorbents, namely Mag-PCMA-T, which contain a maghemite core and a silica mesoporous layer that permanently confines surfactant micelles within the mesopores, were synthesized to achieve simultaneous removal of polycyclic aromatic hydrocarbons (PAHs) (1mg/L) and metal contaminants (1mg/L). The individual removal efficiency of Cd(2+) and acenaphthene using Mag-PCMA-T was evaluated under a range of initial ion concentrations and adsorbent dosages, as well as the competitive adsorption with Cd(2+) and acenaphthene simultaneously present. The isotherms and kinetics of Cd(2+) and acenaphthene sorption onto Mag-PCMA-T were determined. Mag-PCMA-T removed >85% of the acenaphthene in <30min, with relatively high sorption capacity (up to 1060mg/kg). Mag-PCMA-T also exhibited high sorption capacity for Cd(2+) (up to 2250mg/kg). The simultaneous sorption performance was stable across a wide pH range (4-9) as well as in the presence of competitive metal ions (Ca(2+) and Mg(2+)) or natural organic matters. The Mag-PCMA-T can be regenerated and reused, providing a sustainable, fast, convenient, and efficient approach for water treatment. PMID:27450251

  6. The interaction between the outer layer of a mixed ion pair amphiphile/double-chained cationic surfactant vesicle and DNA: a Langmuir monolayer study.

    PubMed

    Lee, Jung; Chang, Chien-Hsiang

    2014-03-21

    The charge density of vesicular bilayers plays an important role in the structure characteristic of the vesicle-DNA complex for gene delivery. In this work, the charge density effect of catanionic vesicle surfaces on the association behavior of the vesicle with DNA was explored with the model Langmuir monolayer approach. The interaction of negatively charged DNA with positively charged Langmuir monolayers composed of catanionic vesicle-forming materials, hexadecyltrimethylammonium-dodecylsulfate (HTMA-DS) and dihexadecyldimethylammonium bromide (DHDAB), was investigated with surface pressure-area isotherms, area-time relaxation curves and Brewster angle microscope images. The results showed that the adsorption of DNA molecules onto the monolayers was enhanced with an increased DHDAB molar fraction (XDHDAB), which was apparently related to the increased charge density of the monolayers. With XDHDAB being increased up to 0.5, the mixed monolayers with a higher XDHDAB, or higher charge density, possessed a more stable characteristic at high surface pressures, at which the molecular status was close to that in a corresponding vesicular bilayer, due to the DHDAB-improved molecular packing/interaction. It was found that the composition of the mixed HTMA-DS-DHDAB monolayers at high surface pressures would be affected by the adsorbed DNA with the extent depending on XDHDAB. For the formation of stable HTMA-DS-DHDAB monolayer-DNA complexes, a strong electrostatic interaction of DNA with a monolayer of high charge density and a high monolayer stability characteristic resulting from DHDAB-improved molecular packing/interaction were thus required. The finding has an implication for the formulation of catanionic vesicles composed of an ion pair amphiphile, HTMA-DS, with DHDAB in gene delivery applications.

  7. Dendrimer-surfactant interactions.

    PubMed

    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.

  8. Surfactant phospholipid metabolism

    PubMed Central

    Agassandian, Marianna; Mallampalli, Rama K.

    2012-01-01

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

  9. Aqueous dual-tailed surfactants simulated on the alumina surface.

    PubMed

    Liu, Zhen; Yu, Jian-Guo; O'Rear, Edgar A; Striolo, Alberto

    2014-08-14

    Atomistic molecular dynamics (MD) simulations were used to compare the morphology of aqueous surfactant self-assembled aggregates on a flat alumina substrate. The substrate was modeled using the CLAYFF force field, and it was considered fully protonated. Three ionic surfactants were considered, all with a sulfate headgroup. The first surfactant was the single-tailed, widely studied sodium dodecyl sulfate (SDS), for which previous simulation results are available on several substrates. The results obtained for this surfactant were used for benchmarking the behavior of two dual-tailed surfactants. These latter surfactants have equal structure, except that in one case both linear tails are composed by seven fully protonated carbon atoms [CH3(CH2)6CHOSO3(CH2)6CH3(-), 2H7], whereas in the other, one tail is composed by seven fully protonated carbon atoms and the other tail is composed by seven fully fluorinated carbon atoms [CF3(CF2)6CHOSO3(CH2)6CH3(-), H7F7]. Our results suggest that preferential interactions lead to surfactant aggregates for H7F7 that differ compared to both those obtained for SDS and 2H7. Although molecular-level geometric structural differences can be invoked to explain differences between H7F7 and SDS aggregates, those between H7F7 and 2H7 aggregates can only be ascribed to atomic-scale interactions. Because as the adsorbed amount of surfactant increases, the self-assembled surfactant aggregates change, suggesting that the substrate on which adsorption occurs effectively evolves as adsorption progresses, compared to bare alumina. The morphological differences observed in our simulations coupled with molecular-level microphase separation might explain, in part, the unusual retrograde adsorption isotherm that has been observed experimentally for H7F7 surfactants on alumina. PMID:25089638

  10. Genetics Home Reference: surfactant dysfunction

    MedlinePlus

    ... Me Understand Genetics Home Health Conditions surfactant dysfunction surfactant dysfunction Enable Javascript to view the expand/collapse boxes. Download PDF Open All Close All Description Surfactant dysfunction is a lung disorder that causes breathing ...

  11. Optimization of metalworking fluid microemulsion surfactant concentrations for microfiltration recycling.

    PubMed

    Zhao, Fu; Clarens, Andres; Skerlos, Steven J

    2007-02-01

    Microfiltration can be used as a recycling technology to increase metalworking fluid (MWF) life span, decrease procurement and disposal costs, and reduce occupational health risks and environmental impacts. The cost-effectiveness of the process can be increased by minimizing fouling interactions between MWFs and membranes. This paper reports on the development of a microfiltration model that establishes governing relationships between MWF surfactant system characteristics and microfiltration recycling performance. The model, which is based on surfactant adsorption/desorption kinetics, queueing theory, and coalescence kinetics of emulsion droplets, is verified experimentally. An analysis of the model and supporting experimental evidence indicates that the selection of surfactant systems minimally adsorb to membranes and lead to a high activation energy of coalescence results in a higher MWF flux through microfiltration membranes. The model also yields mathematical equations that express the optimal concentrations of anionic and nonionic surfactants with which microfiltration flux is maximized for a given combination of oil type, oil concentration, and surfactant types. Optimal MWF formulations are demonstrated for a petroleum oil MWF using a disulfonate/ ethoxylated alcohol surfactant package and for several vegetable oil MWFs using a disulfonate/ethoxylated glyceryl ester surfactant package. The optimization leads to flux increases ranging from 300 to 800% without impact on manufacturing performance. It is further shown that MWF reformulation efforts directed toward increasing microfiltration flux can have the beneficial effect of increasing MWF robustness to deterioration and flux decline in the presence of elevated concentrations of hardwater ions.

  12. Structure and friction of stearic acid and oleic acid films adsorbed on iron oxide surfaces in squalane.

    PubMed

    Doig, Michael; Warrens, Chris P; Camp, Philip J

    2014-01-14

    The structure and friction of fatty acid surfactant films adsorbed on iron oxide surfaces lubricated by squalane are examined using large-scale molecular dynamics simulations. The structures of stearic acid and oleic acid films under static and shear conditions, and at various surface coverages, are described in detail, and the effects of unsaturation in the tail group are highlighted. At high surface coverage, the measured properties of stearic acid and oleic acid films are seen to be very similar. At low and intermediate surface coverages, the presence of a double bond, as in oleic acid, is seen to give rise to less penetration of lubricant in to the surfactant film and less layering of the lubricant near to the film. The kinetic friction coefficient is measured as a function of shear rate within the hydrodynamic (high shear rate) lubrication regime. Lubricant penetration and layering are observed to be correlated with friction coefficient. The friction coefficient with oleic acid depends only weakly on surface coverage, while stearic acid admits more lubricant penetration, and its friction coefficient increases significantly with decreasing surface coverage. Connections between film structure and friction are discussed.

  13. High-efficiency exfoliation of layered materials into 2D nanosheets in switchable CO2/Surfactant/H2O system

    PubMed Central

    Wang, Nan; Xu, Qun; Xu, Shanshan; Qi, Yuhang; Chen, Meng; Li, Hongxiang; Han, Buxing

    2015-01-01

    Layered materials present attractive and important properties due to their two-dimensional (2D) structure, allowing potential applications including electronics, optoelectronics, and catalysis. However, fully exploiting the outstanding properties will require a method for their efficient exfoliation. Here we present that a series of layered materials can be successfully exfoliated into single- and few-layer nanosheets using the driving forces coming from the phase inversion, i.e., from micelles to reverse micelles in the emulsion microenvironment built by supercritical carbon dioxide (SC CO2). The effect of variable experimental parameters including CO2 pressure, ethanol/water ratio, and initial concentration of bulk materials on the exfoliation yield have been investigated. Moreover, we demonstrate that the exfoliated 2D nanosheets have their worthwhile applications, for example, graphene can be used to prepare conductive paper, MoS2 can be used as fluorescent label to perform cellular labelling, and BN can effectively reinforce polymers leading to the promising mechanical properties. PMID:26568039

  14. Formation of a Rigid Hydrophobin Film and Disruption by an Anionic Surfactant at an Air/Water Interface.

    PubMed

    Kirby, Stephanie M; Zhang, Xujun; Russo, Paul S; Anna, Shelley L; Walker, Lynn M

    2016-06-01

    Hydrophobins are amphiphilic proteins produced by fungi. Cerato-ulmin (CU) is a hydrophobin that has been associated with Dutch elm disease. Like other hydrophobins, CU stabilizes air bubbles and oil droplets through the formation of a persistent protein film at the interface. The behavior of hydrophobins at surfaces has raised interest in their potential applications, including use in surface coatings, food foams, and emulsions and as dispersants. The practical use of hydrophobins requires an improved understanding of the interfacial behavior of these proteins, alone and in the presence of added surfactants. In this study, the adsorption behavior of CU at air/water interfaces is characterized by measuring the surface tension and interfacial rheology as a function of adsorption time. CU is found to adsorb irreversibly at air/water interfaces. The magnitude of the dilatational modulus increases with adsorption time and surface pressure until CU eventually forms a rigid film. The persistence of this film is tested through the sequential addition of strong surfactant sodium dodecyl sulfate (SDS) to the bulk liquid adjacent to the interface. SDS is found to coadsorb to interfaces precoated with a CU film. At high concentrations, the addition of SDS significantly decreases the dilatational modulus, indicating disruption and displacement of CU by SDS. Sequential adsorption results in mixed layers with properties not observed in interfaces generated from complexes formed in the bulk. These results lend insight to the complex interfacial interactions between hydrophobins and surfactants. PMID:27164189

  15. Layers

    NASA Astrophysics Data System (ADS)

    Hong, K. J.; Jeong, T. S.; Youn, C. J.

    2014-09-01

    The temperature-dependent photoresponse characteristics of MnAl2S4 layers have been investigated, for the first time, by use of photocurrent (PC) spectroscopy. Three peaks were observed at all temperatures. The electronic origin of these peaks was associated with band-to-band transitions from the valence-band states Γ4( z), Γ5( x), and Γ5( y) to the conduction-band state Γ1( s). On the basis of the relationship between PC-peak energy and temperature, the optical band gap could be well expressed by the expression E g( T) = E g(0) - 2.80 × 10-4 T 2/(287 + T), where E g(0) was estimated to be 3.7920 eV, 3.7955 eV, and 3.8354 eV for the valence-band states Γ4( z), Γ5( x), and Γ5( y), respectively. Results from PC spectroscopy revealed the crystal-field and spin-orbit splitting were 3.5 meV and 39.9 meV. The gradual decrease of PC intensity with decreasing temperature can be explained on the basis of trapping centers associated with native defects in the MnAl2S4 layers. Plots of log J ph, the PC current density, against 1/ T, revealed a dominant trap level in the high-temperature region. By comparing PC and the Hall effect results, we confirmed that this trap level is a shallow donor 18.9 meV below the conduction band.

  16. Regenerative adsorbent heat pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    1991-01-01

    A regenerative adsorbent heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system and at least a portion of the heat of adsorption. A series of at least four compressors containing an adsorbent is provided. A large amount of heat is transferred from compressor to compressor so that heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

  17. Surfactant waterflood oil recovery process

    SciTech Connect

    Kudchadker, M.V.; Whittington, L.E.

    1982-03-16

    Disclosed is a surfactant waterflooding oil recovery process for use in high salinity water-containing formations employing two separate surfactant-containing slugs or a single slug in which the composition is changed from the first to the last portion of the slug injected into the formation. The first portion of the surfactant fluid contains a surfactant combination which exhibits optimum low surface tension characteristics, and the second or latter portion of the surfactant slug contains a blend of surfactants which produces a high viscosity fluid. Use of hydrophilic viscosity-increasing polymer is thus avoided, eliminating the interaction between polymer and surfactant which causes a reduction in surfactant effectiveness.

  18. Mechanisms to explain surfactant responses.

    PubMed

    Jobe, Alan H

    2006-01-01

    Surfactant is now standard of care for infants with respiratory distress syndrome. Surfactant treatments are effective because of complex metabolic interactions between surfactant and the preterm lung. The large treatment dose functions as substrate; it is taken up by the preterm lung and is reprocessed and secreted with improved function. The components of the treatment surfactant remain in the preterm lung for days. If lung injury is avoided, then surfactant inhibition is minimized. Prenatal corticosteroids complement surfactant to further enhance lung function. The magic of surfactant therapy results from the multiple interactions between surfactant and the preterm lung.

  19. Partitioning of complex surfactant mixtures between oil/water/microemulsion phases at high surfactant concentrations

    SciTech Connect

    Graciaa, A.; Lachaise, J.; Sayous, J.G.; Grenier, P.; Yiv, S.

    1983-06-01

    A model describing the partitioning of surfactant molecules between excess and microemulsion phases which are in equilibrium is proposed. The important parameters characterizing the individual molecules comprising the mixture are the critical micelle concentrations in water and the partition coefficients between oil and water phases. The model considers the existence of a separate surfactant phase which is the palisade layer of a micelle and leads to predictions for both fractionation and phase concentrations of surfactant. Predictions based on this model have been compared to experimentally determined quantities and the agreement is good for all cases tested. The model leads to a relatively simple mathematical formulation which can be used to study the effect of varying the overall system surfactant concentration and of changing the system water-to-oil ratio. 21 references.

  20. SURFACTANTS AND SUBSURFACE REMEDIATION

    EPA Science Inventory

    Because of the limitations of pump-and-trat technology, attention is now focused on the feasibility of surfactant use to increase its efficiency. Surfactants have been studied for use in soil washing and enhanced oil recovery. Although similarities exist between the application...

  1. Interfacial reactions of ozone with surfactant protein B in a model lung surfactant system.

    PubMed

    Kim, Hugh I; Kim, Hyungjun; Shin, Young Shik; Beegle, Luther W; Jang, Seung Soon; Neidholdt, Evan L; Goddard, William A; Heath, James R; Kanik, Isik; Beauchamp, J L

    2010-02-24

    Oxidative stresses from irritants such as hydrogen peroxide and ozone (O(3)) can cause dysfunction of the pulmonary surfactant (PS) layer in the human lung, resulting in chronic diseases of the respiratory tract. For identification of structural changes of pulmonary surfactant protein B (SP-B) due to the heterogeneous reaction with O(3), field-induced droplet ionization (FIDI) mass spectrometry has been utilized. FIDI is a soft ionization method in which ions are extracted from the surface of microliter-volume droplets. We report structurally specific oxidative changes of SP-B(1-25) (a shortened version of human SP-B) at the air-liquid interface. We also present studies of the interfacial oxidation of SP-B(1-25) in a nonionizable 1-palmitoyl-2-oleoyl-sn-glycerol (POG) surfactant layer as a model PS system, where competitive oxidation of the two components is observed. Our results indicate that the heterogeneous reaction of SP-B(1-25) at the interface is quite different from that in the solution phase. In comparison with the nearly complete homogeneous oxidation of SP-B(1-25), only a subset of the amino acids known to react with ozone are oxidized by direct ozonolysis in the hydrophobic interfacial environment, both with and without the lipid surfactant layer. Combining these experimental observations with the results of molecular dynamics simulations provides an improved understanding of the interfacial structure and chemistry of a model lung surfactant system subjected to oxidative stress.

  2. Gemini ester quat surfactants and their biological activity.

    PubMed

    Łuczyński, Jacek; Frąckowiak, Renata; Włoch, Aleksandra; Kleszczyńska, Halina; Witek, Stanisław

    2013-03-01

    Cationic gemini surfactants are an important class of surface-active compounds that exhibit much higher surface activity than their monomeric counterparts. This type of compound architecture lends itself to the compound being easily adsorbed at interfaces and interacting with the cellular membranes of microorganisms. Conventional cationic surfactants have high chemical stability but poor chemical and biological degradability. One of the main approaches to the design of readily biodegradable and environmentally friendly surfactants involves inserting a bond with limited stability into the surfactant molecule to give a cleavable surfactant. The best-known example of such a compound is the family of ester quats, which are cationic surfactants with a labile ester bond inserted into the molecule. As part of this study, a series of gemini ester quat surfactants were synthesized and assayed for their biological activity. Their hemolytic activity and changes in the fluidity and packing order of the lipid polar heads were used as the measures of their biological activity. A clear correlation between the hemolytic activity of the tested compounds and their alkyl chain length was established. It was found that the compounds with a long hydrocarbon chain showed higher activity. Moreover, the compounds with greater spacing between their alkyl chains were more active. This proves that they incorporate more easily into the lipid bilayer of the erythrocyte membrane and affect its properties to a greater extent. A better understanding of the process of cell lysis by surfactants and of their biological activity may assist in developing surfactants with enhanced selectivity and in widening their range of application.

  3. Effects of anionic surfactants on ligand-promoted dissolution of iron and aluminum hydroxides.

    PubMed

    Carrasco, Naraya; Kretzschmar, Ruben; Pesch, Marie-Laure; Kraemer, Stephan M

    2008-05-15

    We investigated the influence of the surfactants sodium dodecyl sulfate (SDS) and rhamnolipid (RhL) on ligand-promoted dissolution of goethite (alpha-FeOOH) and boehmite (gamma-AlOOH) at pH 6. The siderophore desferrioxamine B (DFOB), its derivate desferrioxamine D (DFOD), ethylenediaminetetraacetic acid (EDTA), and 8-hydroxyquinoline-5-sulfonic acid (HQS) were used as ligands. The rates of ligand-promoted dissolution of goethite were significantly increased in the presence of low concentrations of anionic surfactants (<80 microM SDS; <6 mg/L RhL). At higher surfactant concentrations, however, the effects of surfactants were negligible. The dissolution rates in the presence of surfactants were not correlated with adsorbed amounts of ligands. Three possible factors contributing to these observations were further investigated and discussed: (i) adsorbed surfactants may influence ligand adsorption by changes in the ligand's surface speciation, (ii) re-adsorption of Fe-DFOB or Fe-DFOD complexes may lead to an underestimation of siderophore-promoted dissolution rates at high surfactant concentrations, and (iii) co-adsorption of protons to goethite with SDS may influence the dissolution rates. However, our results show that none of these three factors can satisfactorily explain the observed effects of anionic surfactants on ligand-promoted dissolution rates of iron and aluminum hydroxides.

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

    SciTech Connect

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

    2012-10-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  6. A new high-performance thin layer chromatography-based assay of detergents and surfactants commonly used in membrane protein studies.

    PubMed

    Barret, Laurie-Anne; Polidori, Ange; Bonneté, Françoise; Bernard-Savary, Pierre; Jungas, Colette

    2013-03-15

    The hydrophobic nature of membrane proteins (MPs) necessitates the use of detergents for their extraction, solubilization and purification. Because the concentration of amphiphiles is crucial in the crystallization process, detergent quantification is essential to routine analysis. Here we describe a quantitative high-performance thin-layer chromatography (HPTLC) method we developed for the detection of small quantities of detergent bound to solubilized MPs. After optimization of aqueous deposit conditions, we show that most detergents widely used in membrane protein crystallography display distinctive mobilities in a mixture of dichloromethane, methanol and acetic acid 32:7.6:0.4 (v/v/v). Migration and derivatization conditions were optimized with n-dodecyl-β-D-maltoside (DDM), the most popular detergent for membrane protein crystallization. A linear calibration curve very well fits our data from 0.1 to 1.6 μg of DDM in water with a limit of detection of 0.05 μg. This limit of detection is the best achieved to date for a routine detergent assay, being not modified by the addition of NaCl, commonly used in protein buffers. With these chromatographic conditions, no prior treatment is required to assess the quantities of detergent bound to purified MPs, thus enabling the quantification of close structure detergents via a single procedure. This HPTLC method, which is fast and requires low sample volume, is fully suitable for routine measurements.

  7. Tuning of protein-surfactant interaction to modify the resultant structure.

    PubMed

    Mehan, Sumit; Aswal, Vinod K; Kohlbrecher, Joachim

    2015-09-01

    Small-angle neutron scattering and dynamic light scattering studies have been carried out to examine the interaction of bovine serum albumin (BSA) protein with different surfactants under varying solution conditions. We show that the interaction of anionic BSA protein (pH7) with surfactant and the resultant structure are strongly modified by the charge head group of the surfactant, ionic strength of the solution, and mixed surfactants. The protein-surfactant interaction is maximum when two components are oppositely charged, followed by components being similarly charged through the site-specific binding, and no interaction in the case of a nonionic surfactant. This interaction of protein with ionic surfactants is characterized by the fractal structure representing a bead-necklace structure of micellelike clusters adsorbed along the unfolded protein chain. The interaction is enhanced with ionic strength only in the case of site-specific binding of an anionic surfactant with an anionic protein, whereas it is almost unchanged for other complexes of cationic and nonionic surfactants with anionic proteins. Interestingly, the interaction of BSA protein with ionic surfactants is significantly suppressed in the presence of nonionic surfactant. These results with mixed surfactants thus can be used to fold back the unfolded protein as well as to prevent surfactant-induced protein unfolding. For different solution conditions, the results are interpreted in terms of a change in fractal dimension, the overall size of the protein-surfactant complex, and the number of micelles attached to the protein. The interplay of electrostatic and hydrophobic interactions is found to govern the resultant structure of complexes.

  8. Metathesis depolymerizable surfactants

    DOEpatents

    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.

  9. Enhanced solubilization of curcumin in mixed surfactant vesicles.

    PubMed

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

    2016-05-15

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

  10. Enhanced solubilization of curcumin in mixed surfactant vesicles.

    PubMed

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

    2016-05-15

    Self-assemblies of equimolar double and single chain mixed ionic surfactants, with increasing numbers of carbon atoms of double chain surfactant, were analyzed on the basis of fluorescence and conductivity results. Attempts were also made to enhance the solubilization of curcumin in aqueous equimolar mixed surfactant systems. Mixed surfactant assembly was successful in retarding the degradation of curcumin in alkaline media (only 25-28 40% degraded in 10h at pH 13). Fluorescence spectroscopy and fluorescence quenching methods were employed to predict the binding position and mechanism of curcumin with self-assemblies. Results indicate that the interactions take place according to both dynamic and static quenching mechanisms and curcumin was distributed in a palisade layer of mixed aggregates. Antioxidant activity (using DPPH radical) and biocompatibility (using calf-thymus DNA) of curcumin-loaded mixed surfactant formulations were also evaluated. The prepared systems improved the stability, solubility and antioxidant activity of curcumin and additionally are biocompatible. PMID:26776022

  11. Adsorption of surfactant lipids by single-walled carbon nanotubes in mouse lung upon pharyngeal aspiration.

    PubMed

    Kapralov, Alexander A; Feng, Wei Hong; Amoscato, Andrew A; Yanamala, Naveena; Balasubramanian, Krishnakumar; Winnica, Daniel E; Kisin, Elena R; Kotchey, Gregg P; Gou, Pingping; Sparvero, Louis J; Ray, Prabir; Mallampalli, Rama K; Klein-Seetharaman, Judith; Fadeel, Bengt; Star, Alexander; Shvedova, Anna A; Kagan, Valerian E

    2012-05-22

    The pulmonary route represents one of the most important portals of entry for nanoparticles into the body. However, the in vivo interactions of nanoparticles with biomolecules of the lung have not been sufficiently studied. Here, using an established mouse model of pharyngeal aspiration of single-walled carbon nanotubes (SWCNTs), we recovered SWCNTs from the bronchoalveolar lavage fluid (BALf), purified them from possible contamination with lung cells, and examined the composition of phospholipids adsorbed on SWCNTs by liquid chromatography mass spectrometry (LC-MS) analysis. We found that SWCNTs selectively adsorbed two types of the most abundant surfactant phospholipids: phosphatidylcholines (PC) and phosphatidylglycerols (PG). Molecular speciation of these phospholipids was also consistent with pulmonary surfactant. Quantitation of adsorbed lipids by LC-MS along with the structural assessments of phospholipid binding by atomic force microscopy and molecular modeling indicated that the phospholipids (∼108 molecules per SWCNT) formed an uninterrupted "coating" whereby the hydrophobic alkyl chains of the phospholipids were adsorbed onto the SWCNT with the polar head groups pointed away from the SWCNT into the aqueous phase. In addition, the presence of surfactant proteins A, B, and D on SWCNTs was determined by LC-MS. Finally, we demonstrated that the presence of this surfactant coating markedly enhanced the in vitro uptake of SWCNTs by macrophages. Taken together, this is the first demonstration of the in vivo adsorption of the surfactant lipids and proteins on SWCNTs in a physiologically relevant animal model.

  12. Surface properties of coal fines in water. 1. Electrokinetics and surfactant adsorption

    SciTech Connect

    Ayub, A.L.; Al Taweel, A.M.; Kwak, J.C.T.

    1985-01-01

    The adsorption of phenol, p-nitrophenol, the nonionic surfactant Triton X-100 (a commercial mixture of octylphenol poly ethoxylates) and the cationic surfactant dodecyltrimethyl ammonium bromide (DTAB) from aqueous solution on coal fines from a coal washing plant has been studied. Adsorbate solution concentrations range from 0-8 x 10/sup -4/ m. For the cationic and nonionic surfactants both adsorption isotherms and electrokinetic isotherms were determined. The adsorption of phenol, but not of Triton X-100 and DTAB, is found to increase with time for periods up to three hundred h. For short contract times (less than thirty h.), the amount of Triton X-100 adsorbed is about three times higher than the amount of phenol adsorbed at the same solution concentration. The electrokinetic data show that the zeta potential of the coal is not affected by the adsorption of Triton X-100. On the other hand, adsorption of the cationic surfactant strongly influences the zeta potential. For negatively charged coal, i.e., at higher solution pH (iep of the coal used is 5.3), the adsorption of cationic surfactant leads to charge reversal at a typical free surfactant concentration often well below 10/sup -4/ molal. 20 references.

  13. Phosphine oxide surfactants revisited.

    PubMed

    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. PMID:26869216

  14. Changes in the surfaces on DDOAB organoclays adsorbed with paranitrophenol-An XRD, TEM and TG study

    SciTech Connect

    Zhou Qin; He Hongping; Frost, Ray L. Xi Yunfei

    2008-12-01

    The adsorption of paranitrophenol on organoclays synthesised by the ion exchange of the surfactant molecule dimethyldioctadecylammonium bromide (DDOAB) of formula (CH{sub 3}(CH{sub 2}){sub 17}){sub 2}NBr(CH{sub 3}){sub 2} has been studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis. The expansion of the montmorillonite depends on the loading of the montmorillonite with dimethyldioctadecylammonium bromide and is related to the arrangement of the surfactant molecules within the clay interlayer. This expansion is altered by the adsorbed paranitrophenol and is observed in the transmission electron microscopic images of the organoclay with adsorbed paranitrophenol. Changes in the surfactant molecular arrangements were analysed by thermogravimetry. The paranitrophenol is sublimed simultaneously with the loss of surfactant. The dehydroxylation temperature of the montmorillonite is decreased upon adsorption of the paranitrophenol indicating a bonding between the paranitrophenol and the hydroxyl units of the montmorillonite.

  15. Effects of Nonionic Surfactants on Bacterial Transport Through Porous Media

    NASA Astrophysics Data System (ADS)

    Brown, D. G.; Jaffe, P. R.

    2001-12-01

    Through a systematic study, it was shown that the nonionic surfactants Brij 30 and Brij 35 were able to enhance the transport of a Sphingomonas sp. through an aquifer sand. The magnitude of the enhancement increased with decreasing solution ionic strength and increasing polyoxyethylene chain length of the surfactant. The mechanism of this enhanced transport appears to be due to expansion of the electric double layer through displacement of the counter ions by the sorbed surfactant. This expanded electric double layer increases the electrostatic repulsion, with a resultant reduction in the collision efficiency and an increase in the Langmuirian blocking parameter. Application of the colloid filtration theory with the experimental parameters of this study shows that nonionic surfactants have the potential to significantly enhance the bacterial travel distance, especially for low ionic strength systems.

  16. Mobility and surfactant migration in EA/MAA latex films; ATR FT-IR spectroscopic study

    SciTech Connect

    Thorstenson, T.A.; Tebelius, L.K.; Urban, M.W.

    1993-12-31

    Although numerous factors such as compatibility, mechanical deformation, and the nature of the substrate have been addressed with respect to surfactant migration and distribution within latex films, latex suspension stability and the effects of particle flocculation are also key issues. In this paper, surfactant behavior in an ethyl acrylate/methacrylic acid/sodium dioctyl sulfosuccinate (EA/MAA/SDOSS) latex system is monitored as a function of stability of the liquid latex suspensions. Particle size data obtained using light scattering reveals an appreciable degree of flocculation over the period of study. It is found that flocculation is paralleled by a significantly increased degree of interfacial surfactant enrichment, a monitored by attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR). It is concluded that the enhanced surfactant exudation observed for flocculated latexes is due to displacement of adsorbed surfactant during the course of flocculation.

  17. Layered double hydroxides as adsorbents and carriers of the herbicide (4-chloro-2-methylphenoxy)acetic acid (MCPA): systems Mg-Al, Mg-Fe and Mg-Al-Fe.

    PubMed

    Bruna, F; Celis, R; Pavlovic, I; Barriga, C; Cornejo, J; Ulibarri, M A

    2009-09-15

    Hydrotalcite-like compounds [Mg(3)Al(OH)(8)]Cl x 4H(2)O; [Mg(3)Fe(OH)(8)]Cl x 4H(2)O; [Mg(3)Al(0.5)Fe(0.5)(OH)(8)]Cl x 4H(2)O (LDHs) and calcined product of [Mg(3)Al(OH)(8)]Cl x 4H(2)O, Mg(3)AlO(4.5) (HT500), were studied as potential adsorbents of the herbicide MCPA [(4-chloro-2-methylphenoxy)acetic acid] as a function of pH, contact time and pesticide concentration, and also as support for the slow release of this pesticide, with the aim to reduce the hazardous effects that it can pose to the environment. The information obtained in the adsorption study was used for the preparation of LDH-MCPA complexes. The results showed high and rapid adsorption of MCPA on the adsorbents as well as that MCPA formulations based on LDHs and HT500 as pesticide supports displayed controlled release properties and reduced herbicide leaching in soil columns compared to a standard commercial MCPA formulation. Thereby, we conclude that the LDHs employed in this study can be used not only as adsorbents to remove MCPA from aqueous solutions, but also as supports for the slow release of this highly mobile herbicide, thus controlling its immediate availability and leaching. PMID:19380194

  18. Remobilizing the Interfaces of Thermocapillary Driven Bubbles Retarded by the Adsorption of a Surfactant Impurity on the Bubble Surface

    NASA Technical Reports Server (NTRS)

    Palaparthi, Ravi; Maldarelli, Charles; Papageorgiou, Dimitri; Singh, Bhim S. (Technical Monitor)

    2000-01-01

    concentrations than the impurity, it adsorbs to the bubble much faster than the impurity when the bubble is formed, and thereby prevents the impurity from adsorbing onto the surface. In addition the rapid kinetic exchange and high bulk concentration maintain a saturated surface with a uniform surface concentrations. This prevents retarding surface tension gradients and keeps the velocity high. In our first report last year, we detailed experimental results which verified the theory of remobilization in ground based experiments in which the steady velocity of rising bubbles was measured in a continuous phase consisting of a glycerol/water mixture containing a polyethylene glycol surfactant C12E6 (CH3(CH2)11(OCH2CH2)6OH). In our report this year, we detail our efforts to describe theoretically the remobilization observed. We construct a model in which a bubble rises steadily by buoyancy in a continuous (Newtonian) viscous fluid containing surfactant with a uniform far field bulk concentration. We account for the effects of inertia as well as viscosity in the flow in the continuous phase caused by the bubble motion (order one Reynolds number), and we assume that the bubble shape remains spherical (viscous and inertial forces are smaller than capillary forces, i e. small Weber and capillary numbers). The surfactant distribution is calculated by solving the mass transfer equations including convection and diffusion in the bulk, and finite kinetic exchange the bulk and the surface. Convective effects dominate diffusive mass transfer in the bulk of the liquid (high Peclet numbers) except in a thin boundary layer near the surface. A finite volume method is used to numerically solve the hydrodynamic and mass transfer equations on a staggered grid which accounts specifically for the thin boundary layer. We present the results of the nondimensional drag as a function of the bulk concentration of surfactant for different rates of kinetic exchange, from which we develop criteria for the

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    Bera, Achinta; Kumar, T.; Ojha, Keka; Mandal, Ajay

    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.

  1. Emulsification through surfactant hydration: the PIC process revisited.

    PubMed

    Roger, Kevin; Cabane, Bernard; Olsson, Ulf

    2011-01-18

    We have performed sudden composition changes on a (surfactant + oil + water) system by adding water to a (surfactant + oil) solution. This composition change quenches the system into a metastable oil-in-water emulsion with a population in the 100 nm range. The conditions for a successful quench are as follows: the initial water content should be below a boundary called the "clearing boundary" (CB), the final water content should be sufficiently beyond CB, and the quench should be fast. We have used high purity components to avoid the complex phase separation patterns that occur with low purity ingredients: the surfactant is octaethylenehexadecyl ether (C(16)E(8)) and the oil is hexadecane (C(16)). Under these conditions, we show that the pathway for this type of quench proceeds through the swelling of the reverse micellar phase by the added water and the formation of a sponge phase. Then, further water addition causes the nucleation of oil droplets in this sponge phase, with a size that matches the spontaneous curvature of the sponge phase. Part of the surfactant remains adsorbed on these droplets, and the rest is expelled as micelles that coexist with the droplets. It is concluded that a PIC emulsification will always lead to a bimodal size distribution with surfactant "wasted" in small micelles. This is in contrast with the more efficient PIT emulsification.

  2. Spatiotemporal measurement of surfactant distribution on gravity-capillary waves

    NASA Astrophysics Data System (ADS)

    Strickland, Stephen; Shearer, Michael; Daniels, Karen

    2015-11-01

    Materials adsorbed to the surface of a fluid - for instance, crude oil, biogenic slicks, or industrial/medical surfactants - will move in response to surface waves. Due to the difficulty of non-invasive measurement of the spatial distribution of a molecular monolayer, little is known about the dynamics that couple the surface waves and the evolving density field. We report measurements of the spatiotemporal dynamics of the density field of an insoluble surfactant driven by gravity-capillary waves in a shallow cylindrical container. Standing Faraday waves and traveling waves generated by the meniscus are superimposed to create a non-trivial surfactant density field. We measure both the height field of the surface using moire-imaging and the density field of the surfactant via the fluorescence of NBD-tagged phosphatidylcholine. Through phase-averaging stroboscopically-acquired images of the density field, we determine that the surfactant accumulates on the leading edge of the traveling meniscus waves and in the troughs of the standing Faraday waves. We fit the spatiotemporal variations in the two fields and report measurements of the wavenumbers as well as a temporal phase shift between the two fields. These measurements suggest that longitudinal waves contribute to the dynamics. Funded by NSF grant DMS-0968258.

  3. Moving liquid surfactant as a way of assessing the properties of surfactant, liquids and surfaces

    NASA Astrophysics Data System (ADS)

    Titov, A. O.; Titov, O. P.; Titov, M. O.; Karbainov, A. N.

    2011-04-01

    In the study of surface phenomena of the main and only instrumentally-defined parameters are surface tension and wetting angle, including in the field of nanotechnology. These indicators were introduced more than 200 years ago, and any new inventions in this field was no more. The university developed a new method and device for determining the surface activity. The basis of the method and device is the use of video cameras to record the droplet size and changes on the surface of the liquid layer of known thickness from the impact of drops of surfactant (surfactant). Committed changes are then processed using computer software and calculated parameters, which can be characterized by a surfactant and surface properties, which is fluid and very liquid. Determine the surface tension or contact angle is not necessary. Measures of surface activity using the method and device are: The amount of fluid that can move one kilogram of surfactant. The value of this index varies from tens of nanometers to hundreds of thousands of units. The indicator can be converted to energy units, joules. The amount of fluid confined by a surface per unit time is calculated based on the first indicator, complements the characterization of surfactant and may be an indicator of surface characteristics and fluid. Propagation speed of the capillary and microwaves. This indicator complements the first two.

  4. Surfactant mixing rules applied to surfactant enhanced alkaline flooding

    SciTech Connect

    Taylor, K.C. )

    1992-01-01

    This paper discusses surfactant mixing rules which have been used to describe crude oil/alkali/surfactant phase behavior, using David Lloydminster crude oil and the surfactant Neodol 25-3S. It was found that at a fixed salinity and alkali concentration, a specific mole fraction of synthetic surfactant to petroleum soap was required to produce optimal phase behavior as the water-to-oil ratio varied. This methodology is useful in understanding the relationship between the variables of water-to-oil ratio and synthetic surfactant concentration in phase behavior systems that produce a petroleum soap.

  5. Effects of surfactants on the desorption of organic contaminants from aquifer materials. Doctoral thesis

    SciTech Connect

    Brickell, J.L.

    1989-08-01

    The efficiency of removing organic contaminants from groundwater aquifers by the pump and treat process is adversely affected by the retardation of the contaminant's mobility due to adsorption onto aquifer material. The use of surfactants in conjunction with the pump and treat process has the potential for improving contaminant mobility by solubilizing the adsorbed contaminant.

  6. Sizing up surfactant synthesis.

    PubMed

    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.

  7. Surfactant-enhanced bioremediation

    SciTech Connect

    Churchill, P.F.; Dudley, R.J.; Churchill, S.A.

    1995-12-31

    This study was undertaken to examine the effect of three structurally related, non-ionic surfactants, Triton X-45, Triton X-100 and Triton X-165, as well as the oleophilic fertilizer, Inipol EAP 22, on the rate of biodegradation of phenanthrene by pure bacterial cultures. Each surfactant dramatically increased the apparent aqueous solubility of phenanthrene. Model studies were conducted to investigate the ability of these surfactants to enhance the rate of transport and uptake of polycyclic aromatic hydrocarbons into bacterial cells, and to assess the impact that increasing the aqueous solubility of hydrocarbons has on their rate of biodegradation. The results indicate that increasing the apparent aqueous solubility of hydrocarbons can lead to enhanced biodegradation rates by two Pseudomonas saccharophila strains. However, the experiments also suggest that some surfactants can inhibit aromatic hydrocarbon biodegradation by certain bacteria. The data also support the hypothesis that surface-active components present in the oleophilic fertilizer formulation, Inipol EAP 22, may have significantly contributed to the positive results reported in tests of remedial agent impact on bioremediation, which was used as a supplemental clean-up technology on Exxon Valdez crude oil-contaminated Alaskan beaches.

  8. Marangoni Effects of a Drop in an Extensional Flow: The Role of Surfactant Physical Chemistry

    NASA Technical Reports Server (NTRS)

    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).

  9. Chain-Chain Interaction between Surfactant Monolayers and long-chain Alkanes and Alcohols

    NASA Astrophysics Data System (ADS)

    Miranda, Paulo; Pflumio, V.; Saijo, H.; Shen, Y. R.

    1997-03-01

    Infrared-Visible Sum-frequency Vibrational Spectroscopy is used to study various self-assembled surfactant monolayers adsorbed at interfaces between fused quartz and liquid alkanes and alcohols. Information about chain conformation can be deduced from the polarization-dependent spectra. Changing the chain lengths of both alkanes and surfactants, we find that if both are sufficiently long, the amount of trans-gauche defects of the surfactant chains can be significantly reduced, via the chain-chain interaction. This, however, will not happen if the surfactant monolayer has too low a surface density. In the case of long-chain alcohols, the alcohol molecules form a hydrogen-bonding network at the interface. To minimize disruption of this network, the surfactant chains become highly disordered and folded into a compact conformation, to reduce their surface area exposed to the alcohol (hydrophobic effect). However, for a sufficiently long alcohol dissolved in a non-polar solvent, the hydrogen-bonding network is disrupted. The alcohol molecules appear to adsorb at the interface and straighten the surfactant chains via the chain-chain interaction. Work supported by DOE under contract No DE-AC03-76SF00098.

  10. The effect of surfactants on the crystallization and polymorphic transformation of glutamic acid

    NASA Astrophysics Data System (ADS)

    Garti, Nissim; Zour, Hadassa

    1997-03-01

    Glutamic acid can crystallize in two polymorphic structures depending on the crystallization regime. The study demonstrates an efficient method to preferentially crystallize the non-stable polymorphic structure (the α-form) in the presence of surface active agents. The rate of transformation was found to depend on the rate of growth of β and not on the rate of dissolution of α. The growth rate of β was a function of the supersaturation of the solute in solution. It was shown that the transformation could be inhibited by the addition of surfactants. The surfactants are capable of adsorbing preferentially to the α-growing crystals and solution mediating (retarding) the transformation of the α- to the β-form. It was suggested that the surfactant nature and steric considerations were important for the inhibition of both nucleation and growth of the β-polymorph. A Langmuir approach indicated that the kinetic parameter was related to the volume of surfactant adsorbed at the crystal surface. No changes in crystal morphology were observed, indicating that adsorption was not specific to any crystal face. Different mechanisms of surfactant adsorption were suggested: adsorption of single molecules at low concentrations of surfactant and formation of hemimicelles at higher concentrations.

  11. Conformational properties of an adsorbed charged polymer.

    PubMed

    Cheng, Chi-Ho; Lai, Pik-Yin

    2005-06-01

    The behavior of a strongly charged polymer adsorbed on an oppositely charged surface of a low-dielectric constant is formulated by the functional integral method. By separating the translational, conformational, and fluctuational degrees of freedom, the scaling behaviors for both the height of the polymer and the thickness of the diffusion layer are determined. Unlike the results predicted by scaling theory, we identified the continuous crossover from the weak compression to the compression regime. All the analytical results are found to be consistent with Monte Carlo simulations. Finally, an alternative (operational) definition of a charged polymer adsorption is proposed. PMID:16089715

  12. Surfactant treatments alter endogenous surfactant metabolism in rabbit lungs

    SciTech Connect

    Oetomo, S.B.; Lewis, J.; Ikegami, M.; Jobe, A.H. )

    1990-04-01

    The effect of exogenous surfactant on endogenous surfactant metabolism was evaluated using a single-lobe treatment strategy to compare effects of treated with untreated lung within the same rabbit. Natural rabbit surfactant, Survanta, or 0.45% NaCl was injected into the left main stem bronchus by use of a Swan-Ganz catheter. Radiolabeled palmitic acid was then given by intravascular injection at two times after surfactant treatment, and the ratios of label incorporation and secretion in the left lower lobe to label incorporation and secretion in the right lung were compared. The treatment procedure resulted in a reasonably uniform surfactant distribution and did not disrupt lobar pulmonary blood flow. Natural rabbit surfactant increased incorporation of palmitate into saturated phosphatidylcholine (Sat PC) approximately 2-fold (P less than 0.01), and secretion of labeled Sat PC increased approximately 2.5-fold in the surfactant-treated left lower lobe relative to the right lung (P less than 0.01). Although Survanta did not alter incorporation, it did increase secretion but not to the same extent as rabbit surfactant (P less than 0.01). Alteration of endogenous surfactant Sat PC metabolism in vivo by surfactant treatments was different from that which would have been predicted by previous in vitro studies.

  13. Surfactants for Bubble Removal against Buoyancy.

    PubMed

    Raza, Md Qaisar; Kumar, Nirbhay; Raj, Rishi

    2016-01-01

    The common phenomenon of buoyancy-induced vapor bubble lift-off from a heated surface is of importance to many areas of science and technology. In the absence of buoyancy in zero gravity of space, non-departing bubbles coalesce to form a big dry patch on the heated surface and heat transfer deteriorates despite the high latent heat of vaporization of water. The situation is worse on an inverted heater in earth gravity where both buoyancy and surface tension act upwards to oppose bubble removal. Here we report a robust passive technique which uses surfactants found in common soaps and detergents to avoid coalescence and remove bubbles downwards, away from an inverted heater. A force balance model is developed to demonstrate that the force of repulsion resulting from the interaction of surfactants adsorbed at the neighboring liquid-vapor interfaces of the thin liquid film contained between bubbles is strong enough to overcome buoyancy and surface tension. Bubble removal frequencies in excess of ten Hz resulted in more than twofold enhancement in heat transfer in comparison to pure water. We believe that this novel bubble removal mechanism opens up opportunities for designing boiling-based systems for space applications. PMID:26743179

  14. Surfactants for Bubble Removal against Buoyancy

    PubMed Central

    Raza, Md. Qaisar; Kumar, Nirbhay; Raj, Rishi

    2016-01-01

    The common phenomenon of buoyancy-induced vapor bubble lift-off from a heated surface is of importance to many areas of science and technology. In the absence of buoyancy in zero gravity of space, non-departing bubbles coalesce to form a big dry patch on the heated surface and heat transfer deteriorates despite the high latent heat of vaporization of water. The situation is worse on an inverted heater in earth gravity where both buoyancy and surface tension act upwards to oppose bubble removal. Here we report a robust passive technique which uses surfactants found in common soaps and detergents to avoid coalescence and remove bubbles downwards, away from an inverted heater. A force balance model is developed to demonstrate that the force of repulsion resulting from the interaction of surfactants adsorbed at the neighboring liquid-vapor interfaces of the thin liquid film contained between bubbles is strong enough to overcome buoyancy and surface tension. Bubble removal frequencies in excess of ten Hz resulted in more than twofold enhancement in heat transfer in comparison to pure water. We believe that this novel bubble removal mechanism opens up opportunities for designing boiling-based systems for space applications. PMID:26743179

  15. Surfactants for Bubble Removal against Buoyancy

    NASA Astrophysics Data System (ADS)

    Raza, Md. Qaisar; Kumar, Nirbhay; Raj, Rishi

    2016-01-01

    The common phenomenon of buoyancy-induced vapor bubble lift-off from a heated surface is of importance to many areas of science and technology. In the absence of buoyancy in zero gravity of space, non-departing bubbles coalesce to form a big dry patch on the heated surface and heat transfer deteriorates despite the high latent heat of vaporization of water. The situation is worse on an inverted heater in earth gravity where both buoyancy and surface tension act upwards to oppose bubble removal. Here we report a robust passive technique which uses surfactants found in common soaps and detergents to avoid coalescence and remove bubbles downwards, away from an inverted heater. A force balance model is developed to demonstrate that the force of repulsion resulting from the interaction of surfactants adsorbed at the neighboring liquid-vapor interfaces of the thin liquid film contained between bubbles is strong enough to overcome buoyancy and surface tension. Bubble removal frequencies in excess of ten Hz resulted in more than twofold enhancement in heat transfer in comparison to pure water. We believe that this novel bubble removal mechanism opens up opportunities for designing boiling-based systems for space applications.

  16. Polymer enrichment decelerates surfactant membranes near interfaces

    NASA Astrophysics Data System (ADS)

    Lipfert, F.; Frielinghaus, H.; Holderer, O.; Mattauch, S.; Monkenbusch, M.; Arend, N.; Richter, D.

    2014-04-01

    Close to a planar surface, lamellar structures are imposed upon otherwise bulk bicontinuous microemulsions. Thermally induced membrane undulations are modified by the presence of the rigid interface. While it has been shown that a pure membrane's dynamics are accelerated close to the interface, we observed nearly unchanged relaxation rates for membranes spiked with large amphiphilic diblock copolymers. An increase of the polymer concentration by a factor of 2-3 for the first and second surfactant membrane layers was observed. We interpret the reduced relaxation times as the result of an interplay between the bending rigidity and the characteristic distance of the first surfactant membrane to the rigid interface, which causes the hydrodynamic and steric interface effects described in Seifert's theory. The influence of these effects on decorated membranes yields a reduction of the frequencies and an amplification of the amplitudes of long-wavelength undulations, which are in accordance to our experimental findings.

  17. Droplet Deformation in an Extensional Flow: The Role of Surfactant Physical Chemistry

    NASA Technical Reports Server (NTRS)

    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

  18. Mixed surfactant systems for enhanced oil recovery

    SciTech Connect

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

    1990-12-01

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

  19. Evaporation of Sessile Droplets Laden with Particles and Insoluble Surfactants.

    PubMed

    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.

  20. Surfactant-Wrapped Multiwalled Carbon Nanotubes in Aquatic Systems: Surfactant Displacement in the Presence of Humic Acid.

    PubMed

    Chang, Xiaojun; Bouchard, Dermont C

    2016-09-01

    Sodium dodecyl sulfate (SDS) facilitates multiwalled carbon nanotube (MWCNT) debundling and enhances nanotube stability in the aqueous environment by adsorbing on the nanotube surfaces, thereby increasing repulsive electrostatic forces and steric effects. The resulting SDS-wrapped MWCNTs are utilized in industrial applications and have been widely employed in environmental studies. In the present study, MWCNTs adsorbed SDS during ultrasonication to form stable MWCNTs suspensions. Desorption of SDS from MWCNTs surfaces was then investigated as a function of Suwannee River Humic Acid (SRHA) and background electrolyte concentrations. Due to hydrophobic effects and π-π interactions, MWCNTs exhibit higher affinity for SRHA than SDS. In the presence of SRHA, SDS adsorbed on MWCNTs was displaced. Cations (Na(+), Ca(2+)) decreased SDS desorption from MWCNTs due to charge screening effects. Interestingly, the presence of the divalent calcium cation facilitated multilayered SRHA adsorption on MWCNTs through bridging effects, while monovalent sodium reduced SRHA adsorption. Results of the present study suggest that properties of MWCNTs wrapped with commercial surfactants will be altered when these materials are released to surface waters and the surfactant coating will be displaced by natural organic matter (NOM). Changes on their surfaces will significantly affect MWCNTs fate in aquatic environments. PMID:27500910

  1. The entropies of adsorbed molecules.

    PubMed

    Campbell, Charles T; Sellers, Jason R V

    2012-10-31

    Adsorbed molecules are involved in many reactions on solid surface that are of great technological importance. As such, there has been tremendous effort worldwide to learn how to predict reaction rates and equilibrium constants for reactions involving adsorbed molecules. Theoretical calculation of both the rate and equilibrium constants for such reactions requires knowing the entropy and enthalpy of the adsorbed molecule. While much effort has been devoted to measuring and calculating the enthalpies of well-defined adsorbates, few measurements of the entropies of adsorbates have been reported. We present here a new way to determine the standard entropies of adsorbed molecules (S(ad)(0)) on single crystal surfaces from temperature programmed desorption data, prove its accuracy by comparison to entropies measured by equilibrium methods, and apply it to published data to extract new entropies. Most importantly, when combined with reported entropies, we find that at high coverage, they linearly track the entropy of the gas-phase molecule at the same temperature (T), such that S(ad)(0)(T) = 0.70 S(gas)(0)(T) - 3.3R (R = the gas constant), with a standard deviation of only 2R over a range of 50R. These entropies, which are ~2/3 of the gas, are huge compared to most theoretical predictions. This result can be extended to reliably predict prefactors in the Arrhenius rate constant for surface reactions involving such species, as proven here for desorption. PMID:23033909

  2. Clouding behaviour in surfactant systems.

    PubMed

    Mukherjee, Partha; Padhan, Susanta K; Dash, Sukalyan; Patel, Sabita; Mishra, Bijay K

    2011-02-17

    A study on the phenomenon of clouding and the applications of cloud point technology has been thoroughly discussed. The phase behaviour of clouding and various methods adopted for the determination of cloud point of various surfactant systems have been elucidated. The systems containing anionic, cationic, nonionic surfactants as well as microemulsions have been reviewed with respect to their clouding phenomena and the effects of structural variation in the surfactant systems have been incorporated. Additives of various natures control the clouding of surfactants. Electrolytes, nonelectrolytes, organic substances as well as ionic surfactants, when present in the surfactant solutions, play a major role in the clouding phenomena. The review includes the morphological study of clouds and their applications in the extraction of trace inorganic, organic materials as well as pesticides and protein substrates from different sources.

  3. Clouding behaviour in surfactant systems.

    PubMed

    Mukherjee, Partha; Padhan, Susanta K; Dash, Sukalyan; Patel, Sabita; Mishra, Bijay K

    2011-02-17

    A study on the phenomenon of clouding and the applications of cloud point technology has been thoroughly discussed. The phase behaviour of clouding and various methods adopted for the determination of cloud point of various surfactant systems have been elucidated. The systems containing anionic, cationic, nonionic surfactants as well as microemulsions have been reviewed with respect to their clouding phenomena and the effects of structural variation in the surfactant systems have been incorporated. Additives of various natures control the clouding of surfactants. Electrolytes, nonelectrolytes, organic substances as well as ionic surfactants, when present in the surfactant solutions, play a major role in the clouding phenomena. The review includes the morphological study of clouds and their applications in the extraction of trace inorganic, organic materials as well as pesticides and protein substrates from different sources. PMID:21296314

  4. Surfactants at the Design Limit.

    PubMed

    Czajka, Adam; Hazell, Gavin; Eastoe, Julian

    2015-08-01

    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.

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

    PubMed

    Erbil, H Yildirim

    2015-08-01

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

  6. Cryogenic adsorber design in a helium refrigeration system

    NASA Astrophysics Data System (ADS)

    Hu, Zhongjun; Zhang, Ning; Li, Zhengyu; Li, Q.

    2012-06-01

    The cryogenic adsorber is specially designed to eliminate impurities in gaseous helium such as O2, and N2 which is normally difficult to remove, based on the reversible cryotrapping of impurities on an activated carbon bed. The coconut shell activated carbon is adopted because of its developed micropore structure and specific surface area. This activated carbon adsorption is mostly determined by the micropore structure, and the adsorption rate of impurities is inversely proportional to the square of the particle sizes. The active carbon absorber's maximum permissible flow velocity is 0.25 m/s. When the gas flow velocity increases, the adsorption diffusion rate of the adsorbent is reduced, because an increase in the magnitude of the velocity resulted in a reduced amount of heat transfer to a unit volume of impure gas. According to the numerical simulation of N2 adsorption dynamics, the appropriate void tower link speed and the saturated adsorption capacity are determined. Then the diameter and height of the adsorber are designed. The mass transfer length should be taken into account in the adsorber height design. The pressure decrease is also calculated. The important factors that influence the adsorber pressure decrease are the void tower speed, the adsorbed layer height, and the active carbon particle shape and size.

  7. Adsorption of a multicomponent rhamnolipid surfactant to soil

    SciTech Connect

    Noordmann, W.H.; Brusseau, M.L.; Janssen, D.B.

    2000-03-01

    The adsorption of rhamnolipid, a multicomponent biosurfactant with potential application in soil remediation, to two sandy soils was investigated using batch and column studies. The surfactant mixture contained six anionic components differing in lipid chain length and number of rhamnose moieties. Batch adsorption experiments indicated that the overall adsorption isotherms of total surfactant and of the individual components leveled off above a concentration at which micelles were formed. Column experiments showed that the retardation factors for the total surfactant and for the individual components decreased with increasing influent concentration. Extended tailing was observed in the distal portion of the surfactant breakthrough curve. The concentration-dependent retardation factors and the extended tailing are in accordance with the nonlinear (concave) adsorption isotherms found in the batch adsorption studies. The more hydrophobic rhamnolipid components were preferentially adsorbed, but adsorption was not correlated with the organic carbon content of the soil. This suggests that adsorption of rhamnolipid to soil is not a partitioning process but mainly an interfacial adsorption process.

  8. Barrier or carrier? Pulmonary surfactant and drug delivery.

    PubMed

    Hidalgo, Alberto; Cruz, Antonio; Pérez-Gil, Jesús

    2015-09-01

    To consider the lung as a target for drug delivery and to optimise strategies directed at the pulmonary route, it is essential to consider the role of pulmonary surfactant, a thin lipid-protein film lining the respiratory surface of mammalian lungs. Membrane-based surfactant multilayers are essential for reducing the surface tension at the respiratory air-liquid interface to minimise the work of breathing. Different components of surfactant are also responsible for facilitating the removal of potentially pathological entities such as microorganisms, allergens or environmental pollutants and particles. Upon inhalation, drugs or nanoparticles first contact the surfactant layer, and these interactions critically affect their lifetime and fate in the airways. This review summarises the current knowledge on the possible role and effects of the pulmonary surfactant system in drug delivery strategies. It also summarises the evidence that suggests that pulmonary surfactant is far from being an insuperable barrier and could be used as an efficient shuttle for delivering hydrophobic and hydrophilic compounds deep into the lung and the organism.

  9. Highly stable surfactant assisted polyaniline nanostructures with enhanced electroactivity

    NASA Astrophysics Data System (ADS)

    Jamdegni, Monika; Kaur, Amarjeet

    2016-05-01

    Different nanostructures of Polyaniline(PANI) i.e. nanospheres, nanorods, nanofibers and layered structures have been successfully synthesized using varied concentration of anionic sodium dodecyl sulphate(SDS) and cationic Hexamethyltriammonium bromide (HTAB) by electrochemical method. Surfactant assisted morphology has been studied using FESEM. Incorporation of surfactants to the polymer matrix has been confirmed using FTIR spectroscopy. Electro activity and stability towards reversible redox activity was studied using cyclic voltammatry and chronoamperometry.The anionic surfactant severely enhances electroactivity and areal capacitance (3 Fcm-2) which was found to be two order higher than PANI film prepared without surfactant (0.039 Fcm-2), attributable to its additional doping effect. Immobilization of large surfactant molecule to polymer matrix inhibits its degradation due to nuleophilic attack ascribed to hydrophobic effect of surfactant. For PANI-SDS redox behavior remained almost same after 1000 reverse redox cycles while for PANI-HTAB we got only marginal changes.Our PANI-SDS samples are promising candidates for electro chromic applications.

  10. Prospects for Simulating Macromolecular Surfactant Chemistry at the Ocean-Atmosphere Boundary

    SciTech Connect

    Elliott, S.; Burrows, Susannah M.; Deal, C.; Liu, Xiaohong; Long, M.; Ogunro, O.; Russell, Lynn M.; Wingenter, O.

    2014-05-01

    Biogenic lipids and polymers are surveyed for their ability to adsorb at the water-air interfaces associated with bubbles, marine microlayers and particles in the overlying boundary layer. Representative ocean biogeochemical regimes are defined in order to estimate local concentrations for the major macromolecular classes. Surfactant equilibria and maximum excess are then derived based on a network of model compounds. Relative local coverage and upward mass transport follow directly, and specific chemical structures can be placed into regional rank order. Lipids and denatured protein-like polymers dominate at the selected locations. The assigned monolayer phase states are variable, whether assessed along bubbles or at the atmospheric spray droplet perimeter. Since oceanic film compositions prove to be irregular, effects on gas and organic transfer are expected to exhibit geographic dependence as well. Moreover, the core arguments extend across the sea-air interface into aerosol-cloud systems. Fundamental nascent chemical properties including mass to carbon ratio and density depend strongly on the geochemical state of source waters. High surface pressures may suppress the Kelvin effect, and marine organic hygroscopicities are almost entirely unconstrained. While bubble adsorption provides a well-known means for transporting lipidic or proteinaceous material into sea spray, the same cannot be said of polysaccharides. Carbohydrates tend to be strongly hydrophilic so that their excess carbon mass is low despite stacked polymeric geometries. Since sugars are abundant in the marine aerosol, gel-based mechanisms may be required to achieve uplift. Uncertainties in the surfactant logic distill to a global scale dearth of information regarding two dimensional kinetics and equilibria. Nonetheless simulations are recommended, to initiate the process of systems level quantification.

  11. Surfactant waterflooding oil recovery method

    SciTech Connect

    Schievelbein, V.H.

    1981-12-29

    Oil is recovered from an underground petroleum reservoir which contains a brine having a salinity of from 50 to 220 kg/m3 total dissolved solids by injecting an alkylarylpolyalkoxy sulfate or alkylpolyalkoxy sulfate surfactant that exhibits phase stability in the brine or diluted brine. The surfactant is injected in an aqueous solution which is prepared with diluted brine which has a salinity slightly less than that required to cause partitioning of the surfactant out of the aqueous phase into the oil-water interface or oil phase. The injection of surfactant is followed by the injecting of a driving slug comprised of either diluted brine or thickened diluted brine.

  12. Surfactant and process for enhanced oil recovery

    SciTech Connect

    Stapp, P. R.

    1984-12-11

    A novel surfactant is formed by reacting maleic anhydride with either a petroleum sulfonate or an alkaryl sulfonate. A surfactant system containing the above surfactant useful in enhanced oil recovery processes is also provided.

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

    PubMed

    Zhong, Xin; Duan, Fei

    2015-05-19

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

  14. Controlling colloid charge in nonpolar liquids with surfactants.

    PubMed

    Smith, Gregory N; Eastoe, Julian

    2013-01-14

    The formation of ions in nonpolar solvents (with relative permittivity ε(r) of approximately 2) is more difficult than in polar liquids; however, these charged species play an important role in many applications, such as electrophoretic displays. The low relative permittivities of these solvents mean that charges have to be separated by large distances to be stable (approximately 28 nm or 40 times that in water). The inverse micelles formed by surfactants in these solvents provide an environment to stabilize ions and charges. Common surfactants used are sodium dioctylsulfosuccinate (Aerosol OT or AOT), polyisobutylene succinimide, sorbitan oleate, and zirconyl 2-ethyl hexanoate. The behavior of charged inverse micelles has been studied on both the bulk and on the microscopic scale and can be used to determine the motion of the micelles, their structure, and the nature of the electrostatic double layer. Colloidal particles are only weakly charged in the absence of surfactant, but in the presence of surfactants, many types, including polymers, metal oxides, carbon blacks, and pigments, have been observed to become positively or negatively charged. Several mechanisms have been proposed as the origin of surface charge, including acid-base reactions between the colloid and the inverse micelle, preferential adsorption of charged inverse micelles, or dissolution of surface species. While most studies vary only the concentration of surfactant, systematic variation of the particle surface chemistry or the surfactant structure have provided insight into the origin of charging in nonpolar liquids. By carefully varying system parameters and working to understand the interactions between surfactants and colloidal surfaces, further advances will be made leading to better understanding of the origin of charge and to the development of more effective surfactants. PMID:23187453

  15. Fabricating electrospun cellulose nanofibre adsorbents for ion-exchange chromatography

    PubMed Central

    Dods, Stewart R.; Hardick, Oliver; Stevens, Bob; Bracewell, Daniel G.

    2015-01-01

    Protein separation is an integral step in biopharmaceutical manufacture with diffusion-limited packed bed chromatography remaining the default choice for industry. Rapid bind-elute separation using convective mass transfer media offers advantages in productivity by operating at high flowrates. Electrospun nanofibre adsorbents are a non-woven fibre matrix of high surface area and porosity previously investigated as a bioseparation medium. The effects of compression and bed layers, and subsequent heat treatment after electrospinning cellulose acetate nanofibres were investigated using diethylaminoethyl (DEAE) or carboxylate (COO) functionalisations. Transbed pressures were measured and compared by compression load, COO adsorbents were 30%, 70% and 90% higher than DEAE for compressions 1, 5 and 10 MPa, respectively, which was attributed to the swelling effect of hydrophilic COO groups. Dynamic binding capacities (DBCs) at 10% breakthrough were measured between 2000 and 12,000 CV/h (2 s and 0.3 s residence times) under normal binding conditions, and DBCs increased with reactant concentration from 4 to 12 mg BSA/mL for DEAE and from 10 to 21 mg lysozyme/mL for COO adsorbents. Comparing capacities of compression loads applied after electrospinning showed that the lowest load tested, 1 MPa, yielded the highest DBCs for DEAE and COO adsorbents at 20 mg BSA/mL and 27 mg lysozyme/mL, respectively. At 1 MPa, DBCs were the highest for the lowest flowrate tested but stabilised for flowrates above 2000 CV/h. For compression loads of 5 MPa and 10 MPa, adsorbents recorded lower DBCs than 1 MPa as a result of nanofibre packing and reduced surface area. Increasing the number of bed layers from 4 to 12 showed decreasing DBCs for both adsorbents. Tensile strengths were recorded to indicate the mechanical robustness of the adsorbent and be related to packing the nanofibre adsorbents in large scale configurations such as pleated cartridges. Compared with an

  16. Surfactant phosphatidylcholine metabolism and surfactant function in preterm, ventilated lambs

    SciTech Connect

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

    1989-02-01

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

  17. A surface extended X-ray absorption fine structure study of tellurium adsorbed onto Si(100)

    NASA Astrophysics Data System (ADS)

    Burgess, S. R.; Cowie, B. C. C.; Wilks, S. P.; Dunstan, P. R.; Dunscombe, C. J.; Williams, R. H.

    1996-09-01

    The adsorption of tellurium on Si(100) has been studied using surface extended X-ray adsorption fine structure (SEXAFS) and X-ray standing wave spectroscopy (XSW). This particular system is of interest due to its potential applicability in the surfactant aided growth of CdHgTeCdTeSi(100) based infra-red detectors. The Te/Si(100) structure was generated by depositing a thick layer (˜ 100 Å) of CdTe onto a clean Si (2 × 1) double domain surface, and annealing the sample to 350°C. This resulted is a ˜ 1 ML Te terminated surface where the (2 × 1) reconstruction was lost in favour of a (1 × 1) symmetry. X-ray absorption of the Te L 3 edge ( E = 4341 eV), with a photon energy range of 4440-4700 eV, was probed using a total yield detection scheme. The SEXAFS results indicated that the Te atoms sat in 2-fold bridge sites directly above a fourth layer Si atom. The corresponding bond length was measured to be 2.52 ± 0.05 Å. The XSW measurements of the (400) reflection gave a coherent position of 1.63 ± 0.03 Å and a coherent fraction of 0.65. This is consistent with the breaking of the SiSi dimers and thus could be an example of the phenomena of adsorbate-induced dereconstruction of the surface. These results are compared with those of Bennet et al. who examined a similar system using soft X-ray photoemission (SXPS) and the STM study of Yoshikawa et al.

  18. Rotary adsorbers for continuous bulk separations

    DOEpatents

    Baker, Frederick S.

    2011-11-08

    A rotary adsorber for continuous bulk separations is disclosed. The rotary adsorber includes an adsorption zone in fluid communication with an influent adsorption fluid stream, and a desorption zone in fluid communication with a desorption fluid stream. The fluid streams may be gas streams or liquid streams. The rotary adsorber includes one or more adsorption blocks including adsorbent structure(s). The adsorbent structure adsorbs the target species that is to be separated from the influent fluid stream. The apparatus includes a rotary wheel for moving each adsorption block through the adsorption zone and the desorption zone. A desorption circuit passes an electrical current through the adsorbent structure in the desorption zone to desorb the species from the adsorbent structure. The adsorbent structure may include porous activated carbon fibers aligned with their longitudinal axis essentially parallel to the flow direction of the desorption fluid stream. The adsorbent structure may be an inherently electrically-conductive honeycomb structure.

  19. Spontaneous surface self-assembly in protein-surfactant mixtures: interactions between hydrophobin and ethoxylated polysorbate surfactants.

    PubMed

    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.

  20. Surfactant adsorption kinetics in microfluidics

    PubMed Central

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

    2016-01-01

    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. PMID:27688765

  1. Surfactant-assisted coal liquefaction

    NASA Technical Reports Server (NTRS)

    Hsu, G. C.

    1977-01-01

    Improved process of coal liquefaction utilizing nonaqueous surfactant has increased oil yield from 50 to about 80%. Asphaltene molecule formation of colloid particles is prevented by surfactant. Separated molecules present more surface area for hydrogenation reaction. Lower requirements for temperature, pressure, and hydrogen lead to reduction in capital and operation costs.

  2. Novel Approaches to Surfactant Administration

    PubMed Central

    Gupta, Samir; Donn, Steven M.

    2012-01-01

    Surfactant replacement therapy has been the mainstay of treatment for preterm infants with respiratory distress syndrome for more than twenty years. For the most part, surfactant is administered intratracheally, followed by mechanical ventilation. In recent years, the growing interest in noninvasive ventilation has led to novel approaches of administration. This paper will review these techniques and the associated clinical evidence. PMID:23243504

  3. ADSORPTION OF SURFACTANT ON CLAYS

    EPA Science Inventory

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

  4. Surfactant monitoring by foam generation

    DOEpatents

    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.

  5. On-line surfactant monitoring

    SciTech Connect

    Mullen, K.I.; Neal, E.E.; Soran, P.D.; Smith, B.

    1995-04-01

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

  6. Direct Observation Of Nanoparticle-Surfactant Interactions Using Small Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Kumar, Sugam; Aswal, V. K.

    2010-12-01

    Interactions of anionic silica nanoparticles with anionic, cationic and nonionic surfactants have directly been studied by contrast variation small angle neutron scattering (SANS). The measurements are performed on 1 wt% of both silica nanoparticles and surfactants of anionic sodium dodecyle sulphate (SDS), cationic dodecyltrimethyl ammonium bromide (DTAB) and non-ionic polyoxyethylene 10 lauryl ether (C12E10) in aqueous solution. We show that there is no direct interaction in the case of SDS with silica particles, whereas strong interaction for DTAB leads to the aggregation of silica particles. The interaction of C12E10 is found through the micelles adsorbed on the silica particles.

  7. Production And Artile Of Iron/Surfactant-Modified Zeolite Pellets To Retain And Destroy Water Pollutants

    DOEpatents

    BOWMAN, ROBERT S.; [et al

    2001-07-17

    A method of producing a pollutant adsorption and degradation article, and such article, are provided. At least one adsorbent is mixed with at least one pollutant transforming agent to form a mixture. This mixture is compacted to form a porous, highly permeable article. If necessary, the article can be modified with surfactant either after the compacting step or by adding the surfactant to the mixture prior to the compacting step. In addition, if necessary, a binding agent can be added to the mixture prior to the compacting step.

  8. Surfactant and Plasticizer Segregation in Thin Poly(vinyl alcohol) Films.

    PubMed

    Briddick, Arron; Li, Peixun; Hughes, Arwel; Courchay, Florence; Martinez, Alberto; Thompson, Richard L

    2016-01-26

    The vertical depth distributions of individual additive components [cetyltrimethylammonium bromide (CTAB), deuterated pentaethylene glycol monododecyl ether (d25-C12E5), and deuterated glycerol (d-glycerol)] in PVA films have been isolated and explored by ion beam analysis techniques and neutron reflectometry. The additives display an unexpectedly rich variety of surface and interfacial behaviors in spin-cast films. In separate binary films with PVA, both d-glycerol and CTAB were evenly distributed, whereas d25-C12E5 showed clear evidence for surface and interfacial segregation. The behavior of each surfactant in PVA was reversed when the plasticizer (glycerol) was also incorporated into the films. With increasing plasticizer content, the surface activity of d25-C12E5 systematically decreased, but remarkably, when glycerol and CTAB were present in PVA, the surface and interfacial activities of CTAB increased dramatically in the presence of glycerol. Quantification of the surface excess by ion beam analysis revealed that, in many cases, the adsorbed quantity far exceeded what could reasonably be explained by a single layer, thus indicating a wetting transition of the small molecules at the surface or interface of the film. It appears that the surface and interfacial behaviors are partly driven by the relative surface energies of the components, but are also significantly augmented by the incompatibility of the components. PMID:26717264

  9. Surfactant Facilitated Spreading of Aqueous Drops on Hydrophobic Surfaces

    NASA Technical Reports Server (NTRS)

    Kumar, Nitin; Couzis, Alex; Maldareili, Charles; Singh, Bhim (Technical Monitor)

    2001-01-01

    Microgravity technologies often require aqueous phases to spread over nonwetting hydrophobic solid surfaces. Surfactants facilitate the wetting of water on hydrophobic surfaces by adsorbing on the water/air and hydrophobic solid/water interfaces and lowering the surface tensions of these interfaces. The tension reductions decrease the contact angle, which increases the equilibrium wetted area. Hydrocarbon surfactants; (i.e., amphiphiles with a hydrophobic moiety consisting of an extended chain of (aliphatic) methylene -CH2- groups attached to a large polar group to give aqueous solubility) are capable of reducing the contact angles on surfaces which are not very hydrophobic, but do not reduce significantly the contact angles of the very hydrophobic surfaces such as parafilm, polyethylene or self assembled monolayers. Trisiloxane surfactants (amphiphiles with a hydrophobe consisting of methyl groups linked to a trisiloxane backbone in the form of a disk ((CH3)3-Si-O-Si-O-Si(CH3)3) and an extended ethoxylate (-(OCH2CH2)a-) polar group in the form of a chain with four or eight units) can significantly reduce the contact angle of water on a very hydrophobic surface and cause rapid and complete (or nearly complete) spreading (termed superspreading). The overall goal of the research described in this proposal is to establish and verify a theory for how trisiloxanes cause superspreading, and then use this knowledge as a guide to developing more general hydrocarbon based surfactant systems which superspread. We propose that the trisiloxane surfactants superspread because their structure allows them to strongly lower the high hydrophobic solid/aqueous tension when they adsorb to the solid surface. When the siloxane adsorbs, the hydrophobic disk parts of the molecule adsorb onto the surface removing the surface water. Since the cross-sectional area of the disk is larger than that of the extended ethoxylate chain, the disks can form a space-filling mat on the surface which

  10. Enhancing the Thermocapillary Migration of Bubbles Retarded by the Adsorption of Surfactant Impurities By Using Remobilizing Surfactants

    NASA Astrophysics Data System (ADS)

    Maldarelli, Charles; Balasubramaniam, R.

    2002-11-01

    Thermocapillary migration is a method for moving bubbles in space in the absence of buoyancy. A temperature gradient is applied to the continuous phase in which a bubble is situated, and the applied gradient impressed on the bubble surface causes one pole of the drop to be cooler than the opposite pole. As the surface tension is a decreasing function of temperature, the cooler pole pulls at the warmer pole, creating a flow which propels the bubble in the direction of the warmer fluid. A major impediment to the practical use of thermocapillarity to direct the movement of bubbles in space is the fact that surfactant impurities which are unavoidably present in the continuous phase can significantly reduce the migration velocity. A surfactant impurity adsorbed onto the bubble interface is swept to the trailing end of the bubble. When bulk concentrations are low (which is the case with an impurity), diffusion of surfactant to the front end is slow relative to convection, and surfactant collects at the back end of the bubble. Collection at the back lowers the surface tension relative to the front end setting up a reverse tension gradient. (This can also be the case if kinetic desorption of surfactant at the back end of the bubble is much slower than convection.) For buoyancy driven bubble motions in the absence of a thermocapillarity, the tension gradient opposes the surface flow, and reduces the surface and terminal velocities (the interface becomes more solid-like and bubbles translate as solid particles). When thermocapillary forces are present, the reverse tension gradient set up by the surfactant accumulation reduces the temperature induced tension gradient, and can decrease to near zero the bubble's thermocapillary velocity. The objective of our research is to develop a method for enhancing the thermocapillary migration of bubbles which have been retarded by the adsorption onto the bubble surface of a surfactant impurity. Our remobilization theory proposes to use

  11. Regenerable granular carbon nanotubes/alumina hybrid adsorbents for diclofenac sodium and carbamazepine removal from aqueous solution.

    PubMed

    Wei, Haoran; Deng, Shubo; Huang, Qian; Nie, Yao; Wang, Bin; Huang, Jun; Yu, Gang

    2013-08-01

    A novel granular carbon nanotubes (CNTs)/alumina (Al2O3) hybrid adsorbent with good sorption and regeneration properties was successfully prepared by mixing CNTs with surfactant Brij 35 and pseudo boehmite, followed by calcining to remove surfactant and form porous granules. Alumina binder increased the mechanical strength, hydrophilicity and porosity of the granular adsorbent, while the dispersed CNTs in the granular adsorbent were responsible for the sorption of diclofenac sodium (DS) and carbamazepine (CBZ). Scanning electron microscopy (SEM) showed that the CNTs and Al2O3 were mixed well and the porous structure was formed in the granular adsorbent. The high surface area and appropriate pore size of granular CNTs/Al2O3 adsorbent were favorable for sorption. The sorption of DS decreased with increasing solution pH, while pH had little effect on CBZ sorption. The maximum sorption capacities of CBZ and DS on the CNTs/Al2O3 adsorbent were 157.4 and 106.5 μmol/g according to the Langmuir fitting. Moreover, the spent CNTs/Al2O3 adsorbent can be thermally regenerated at 400 °C in air due to the thermal stability of CNTs. The removal of CBZ and DS changed a little in the initial reuse cycles and then kept relatively constant until tenth cycles. The adsorbed CBZ and DS were decomposed in the regeneration process. This regenerable adsorbent may find potential application in water or wastewater treatment for the removal of some micropollutants such as pharmaceuticals.

  12. Regenerable granular carbon nanotubes/alumina hybrid adsorbents for diclofenac sodium and carbamazepine removal from aqueous solution.

    PubMed

    Wei, Haoran; Deng, Shubo; Huang, Qian; Nie, Yao; Wang, Bin; Huang, Jun; Yu, Gang

    2013-08-01

    A novel granular carbon nanotubes (CNTs)/alumina (Al2O3) hybrid adsorbent with good sorption and regeneration properties was successfully prepared by mixing CNTs with surfactant Brij 35 and pseudo boehmite, followed by calcining to remove surfactant and form porous granules. Alumina binder increased the mechanical strength, hydrophilicity and porosity of the granular adsorbent, while the dispersed CNTs in the granular adsorbent were responsible for the sorption of diclofenac sodium (DS) and carbamazepine (CBZ). Scanning electron microscopy (SEM) showed that the CNTs and Al2O3 were mixed well and the porous structure was formed in the granular adsorbent. The high surface area and appropriate pore size of granular CNTs/Al2O3 adsorbent were favorable for sorption. The sorption of DS decreased with increasing solution pH, while pH had little effect on CBZ sorption. The maximum sorption capacities of CBZ and DS on the CNTs/Al2O3 adsorbent were 157.4 and 106.5 μmol/g according to the Langmuir fitting. Moreover, the spent CNTs/Al2O3 adsorbent can be thermally regenerated at 400 °C in air due to the thermal stability of CNTs. The removal of CBZ and DS changed a little in the initial reuse cycles and then kept relatively constant until tenth cycles. The adsorbed CBZ and DS were decomposed in the regeneration process. This regenerable adsorbent may find potential application in water or wastewater treatment for the removal of some micropollutants such as pharmaceuticals. PMID:23579087

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

    PubMed

    Parra, Elisa; Pérez-Gil, Jesús

    2015-01-01

    The respiratory surface in the mammalian lung is stabilized by pulmonary surfactant, a membrane-based system composed of multiple lipids and specific proteins, the primary function of which is to minimize the surface tension at the alveolar air-liquid interface, optimizing the mechanics of breathing and avoiding alveolar collapse, especially at the end of expiration. The goal of the present review is to summarize current knowledge regarding the structure, lipid-protein interactions and mechanical features of surfactant membranes and films and how these properties correlate with surfactant biological function inside the lungs. Surfactant mechanical properties can be severely compromised by different agents, which lead to surfactant inhibition and ultimately contributes to the development of pulmonary disorders and pathologies in newborns, children and adults. A detailed comprehension of the unique mechanical and rheological properties of surfactant layers is crucial for the diagnostics and treatment of lung diseases, either by analyzing the contribution of surfactant impairment to the pathophysiology or by improving the formulations in surfactant replacement therapies. Finally, a short review is also included on the most relevant experimental techniques currently employed to evaluate lung surfactant mechanics, rheology, and inhibition and reactivation processes.

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

    PubMed

    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.

  15. Highly dealuminated Y zeolite as efficient adsorbent for the hydrophobic fraction from wastewater treatment plants effluents.

    PubMed

    Navalon, Sergio; Alvaro, Mercedes; Garcia, Hermenegildo

    2009-07-15

    In this work we report that highly dealuminated zeolite Y is a hydrophobic material that is able to remove selectively fatty acids and hydrocarbon compounds from the effluent of an urban wastewater treatment plant (UWTP). This adsorbent capability of zeolite Y could lead to an improved quality of UWTP effluents. Typical domestic wastewaters contain detergents, soaps and surfactants that are only partially removed in conventional UWTP. In the present work using an effluent from a UWTP located at Ribarroja del Turia (Valencia, Spain) containing 10 ppm of total organic carbon, we have been able to retain by adsorption on the dealuminated Y zeolite up to 16 and 60% of the organic matter of the effluent at pH values 7.2 and 4, respectively. Characterization of the adsorbed organic matter by Fourier transformed infrared (FT-IR), (1)H NMR and GC-MS after derivatization has shown that the zeolite adsorbs selectively the hydrophobic compounds of the effluent.

  16. Influence of polymer-surfactant interactions on o/w emulsion properties and microcapsule formation.

    PubMed

    Petrovic, Lidija B; Sovilj, Verica J; Katona, Jaroslav M; Milanovic, Jadranka L

    2010-02-15

    The aim of this work was to investigate the influence of interactions between 1.00%w/w hydroxypropylmethyl cellulose (HPMC) and the anionic surfactant sodium dodecylsulfate (SDS) on the properties of 20%w/w sunflower oil/water emulsion and the corresponding microcapsules obtained by spray drying technique. On the basis of the viscosity and rheological measurements, particle size and particle size distribution, and stability assessment, it was concluded that the emulsion characteristics depend strongly on the interaction mechanism. Significant increase in viscosity and non-Newtonian thixotropic behavior was observed in the SDS concentration range from 0.15 to 1.00%w/v, corresponding to HPMC-SDS interactions in the continuous phase. In the interaction region, a three-dimensional network is formed in the continuous phase by intermolecular binding of SDS molecules to the adjacent HPMC chains, which contributes to increase in the viscosity and thixotropic properties. The mean diameter of emulsion particles, d(vs), decreases with increase in SDS concentration, but emulsion stability depends on the adsorption layer structure, i.e. HPMC-SDS interactions. The HPMC/SDS complex adsorbed at the o/w interface makes the layer more compact, enhancing thus emulsion stability. Microcapsules, obtained in the form of powder by spray drying of emulsions, have good redispersibility in water, but their stability changes depending on the HPMC-SDS interaction mechanism, i.e., the HPMC/SDS complex forms a more compact layer that is resistant to breaking during the drying process. The highest encapsulation efficiency was found in the interaction region.

  17. Surfactant Saturation of Drops in Microgravity by Terrestrial Simulation

    NASA Astrophysics Data System (ADS)

    Viviani, Antonio

    It is well known that diffusion plays an appreciable role in mass transfer only in the case of weak gravitational convection. However, even under such conditions the use of a surfactant as a dif-fusing substance essentially complicates the mass transfer processes. The appearance of gas or liquid inclusions in the surfactant solution causes the development of solutocapillary motion on their surface, which may become a generator of the large-scale flows in the surrounding liquid, especially in microgravity conditions. The paper presents the results of terrestrial simulation of such flows during saturation of the drop of weakly soluble fluid by a surfactant from its water solution forming a thin ( 1 ) horizontal layer. In our experiments, we used chlorobenzene and water as the basic fluids of the drop and the surrounding medium, respectively, and isopropyl alcohol -as a surfactant. The initial concentration 0 of the alcohol in the solution ranged from 5 to 50%. This lent specific feature to the saturation process, manifesting itself in the fact that at concentration higher than 25% a mutual dissolution of water and chlorobenzene began to increase. Visualization of flow structures and concentration fields showed that in laboratory conditions even at maximum suppression of the gravitational convection the saturation of the surfactant is a rather complicated process specified by the initial surfactant concentration in the solution and by the degree of the solution homogeneity. In the case of initially homoge-neous solution, a complicated character of mass transfer between the drop and the surrounding medium is evidently due to the small values of surfactant diffusion coefficients in basic flu-ids. Penetration of the surfactant into the drop leads to the formation of local inhomigeneities of the solution density at both sides of the interface and to the development of a slow three-dimensional flow of gravitational nature. An increase in the concentration gives rise to a

  18. Determination of 1-naphthol and 2-naphthol from environmental waters by magnetic solid phase extraction with Fe@MgAl-layered double hydroxides nanoparticles as the adsorbents prior to high performance liquid chromatography.

    PubMed

    Zhou, Qingxiang; Lei, Man; Li, Jing; Zhao, Kuifu; Liu, Yongli

    2016-04-01

    Magnetic Fe@MgAl-layered double hydroxides (MgAl-LDHs) composite was firstly synthesized by coating MgAl-layered double hydroxides on the surface of the dispersed nanoscale zero valent irons with co-precipitation method and characterized by transmission electron microscopy and X-ray diffraction techniques. The synthesized Fe@MgAl-LDHs nanoparticles were investigated for magnetic solid phase extraction (MSPE) of 1-naphthol and 2-naphthol from the water samples. The elutent containing 1-naphthol and 2-naphthol was analyzed by high performance liquid chromatography with variable wavelength detection (HPLC-UV). Under optimal conditions, there is good linear relationship between the concentration and the peak area in the range of 0.5-200 μgL(-1) with the correlation coefficients (r(2)) above 0.998 for 1-naphthol and 2-naphthol. The limits of detection were 0.22 μgL(-1) and 0.19 μgL(-1) for 1-naphthol and 2-naphthol, respectively, and precisions were both below 2.5% (n=6). The real water analysis demonstrated that the spiked recoveries were in the range of 79.2-80.9% (n=3). All these results indicated that the developed MSPE-HPLC-UV method was proved to be an efficient tool for the analysis of naphthols.

  19. Quantifying nisin adsorption behavior at pendant PEO layers

    PubMed Central

    Dill, Justen K.; Auxier, Julie A.; Schilke, Karl F.; McGuire, Joseph

    2013-01-01

    The antimicrobial peptide nisin shows potent activity against Gram-positive bacteria including the most prevalent implant-associated pathogens. Its mechanism of action minimizes the opportunity for the rise of resistant bacteria and it does not appear to be toxic to humans, suggesting good potential for its use in antibacterial coatings for selected medical devices. A more quantitative understanding of nisin loading and release from polyethylene oxide (PEO) brush layers will inform new strategies for drug storage and delivery, and in this work optical waveguide lightmode spectroscopy was used to record changes in adsorbed mass during cyclic adsorption-elution experiments with nisin, at uncoated and PEO-coated surfaces. PEO layers were prepared by radiolytic grafting of Pluronic® surfactant F108 or F68 to silanized silica surfaces, producing long- or short-chain PEO layers, respectively. Kinetic patterns were interpreted with reference to a model accounting for history-dependent adsorption, in order to evaluate rate constants for nisin adsorption and desorption, as well as the effect of pendant PEO on the lateral clustering behavior of nisin. Nisin adsorption was observed at the uncoated and F108-coated surfaces, but not at the F68-coated surfaces. Nisin showed greater resistance to elution by peptide-free buffer at the uncoated surface, and lateral rearrangement and clustering of adsorbed nisin was apparent only at the uncoated surface. We conclude peptide entrapment at the F108-coated surface is governed by a hydrophobic inner region of the PEO brush layer that is not sufficient for nisin entrapment in the case of the shorter PEO chains of the F68-coated surface. PMID:23445762

  20. Surfactant and process for enhanced oil recovery

    SciTech Connect

    Stapp, P. R.

    1985-03-12

    A novel surfactant is formed by reacting maleic anhydride with a polynuclear aromatic compound having a molecular weight of at least 155. A novel surfactant system useful in enhanced oil recovery containing the above surfactant is also provided. In addition, an improved process for the enhanced recovery of oil is provided utilizing the novel surfactant system.

  1. Sorption of phenol and 4-chlorophenol onto pumice treated with cationic surfactant.

    PubMed

    Akbal, Feryal

    2005-02-01

    In this study the sorption of phenol and 4-chlorophenol on pumice modified with the cationic surfactants hexadecyltrimethyl ammonium bromide (HDTMA) and benzyldimethyl tetradecylammonium chloride (BDTDA) was investigated. Experimental studies indicate that HDTMA-pumice and BDTDA-pumice have the capability to remove phenol and 4-chlorophenol from aqueous solution. The influence of initial concentration and adsorbent dosage was studied. The adsorption of phenol and 4-chlorophenol increased with increasing initial concentration and decreased with increasing amount of adsorbent used. The Freundlich adsorption isotherm was found to describe well the equilibrium adsorption data. The parameters of the Freundlich model have been determined using the adsorption data.

  2. Surfactant waterflooding enhanced oil recovery process

    SciTech Connect

    Schievelbein, V.H.

    1984-07-17

    Disclosed is a surfactant waterflooding enhanced oil recovery process and surfactant fluid suitable for use in an enhanced oil recovery process which accomplishes an increase in the amount of oil recovered over prior art methods. The surfactant fluid contains an alkylpolyalkoxy sulfate or alkylarylpolyalkoxy sulfate, or an alkylpolyalkoxyalkylene sulfonate or alkylarylpolyalkoxyalkylene sulfonate, either alone or in combination with an organic sulfonate anionic surfactant, such as petroleum sulfonate. The optimum average degree of ethoxylation of the alkoxy sulfate or alkoxy sulfonate surfactant is identified, and the surfactant fluid is formulated with a mixture of ethoxylated and sulfated or ethoxylated and sulfonated surfactants, having a broad even range of degree of ethoxylation.

  3. Pulmonary surfactant for neonatal respiratory disorders.

    PubMed

    Merrill, Jeffrey D; Ballard, Roberta A

    2003-04-01

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

  4. Structural Studies of Protein-Surfactant Complexes

    SciTech Connect

    Chodankar, S. N.; Aswal, V. K.; Wagh, A. G.

    2008-03-17

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

  5. Pulmonary surfactant for neonatal respiratory disorders.

    PubMed

    Merrill, Jeffrey D; Ballard, Roberta A

    2003-04-01

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

  6. Chitosan membrane adsorber for low concentration copper ion removal.

    PubMed

    Wang, Xiaomin; Li, Yanxiang; Li, Haigang; Yang, Chuanfang

    2016-08-01

    Thin chitosan membranes with symmetric and interconnected pore structure were prepared using silica as porogen, and their physical properties including pore structure, pore size distribution, porosity and water affinity were analyzed. The membrane showed a maximum Cu(II) adsorption capacity of 87.5mg/g in static adsorption, and the adsorption fitted pseudo-second order kinetics and Toth adsorption isotherm. The membranes were then stacked in layers as an adsorber to remove small concentration Cu(II) from water dynamically. At feed concentration of 5mg/L, the adsorber could retain Cu(II) effectively when its thickness reached over 200μm, and the performance was further improved by using more membranes layers. Within a certain limit, the adsorber showed a 'flow-independent' loading behavior, an indication of fast mass transfer inside the membrane. The adsorption process was correlated well with bed depth service time (BDST) model, Thomas model and Yoon and Nelson model, and the adsorber was also found to be regenerable and re-usable. PMID:27112875

  7. Light-controllable dispersion and recovery of graphenes and carbon nanotubes using a photo-switchable surfactant

    NASA Astrophysics Data System (ADS)

    McCoy, Thomas M.; Liu, Amelia C. Y.; Tabor, Rico F.

    2016-03-01

    The aqueous dispersibility of carbon-based nanomaterials, namely graphene oxide (GO), reduced graphene oxide (rGO) and carbon nanotubes (CNTs), can be controlled by light via the photoisomerisation of a photoswitchable surfactant molecule adsorbed to the surface of these materials. By incorporating a cationic azobenzene photosurfactant into these systems, GO, rGO and CNT dispersions can be separated and redispersed on command utilising UV radiation at 365 nm, whereby the surfactant molecules change from the trans to the cis isomer. This increases their aqueous solubility and in turn, alters their adsorption affinity for the GO and rGO sheets such that the ratio of free to adsorbed surfactant molecules changes significantly, allowing for reversible phase separation of the colloids. These effects present a unique method for controlling the dispersion behaviour of two-dimensional nanomaterials using light as a clean and low energy external stimulus.The aqueous dispersibility of carbon-based nanomaterials, namely graphene oxide (GO), reduced graphene oxide (rGO) and carbon nanotubes (CNTs), can be controlled by light via the photoisomerisation of a photoswitchable surfactant molecule adsorbed to the surface of these materials. By incorporating a cationic azobenzene photosurfactant into these systems, GO, rGO and CNT dispersions can be separated and redispersed on command utilising UV radiation at 365 nm, whereby the surfactant molecules change from the trans to the cis isomer. This increases their aqueous solubility and in turn, alters their adsorption affinity for the GO and rGO sheets such that the ratio of free to adsorbed surfactant molecules changes significantly, allowing for reversible phase separation of the colloids. These effects present a unique method for controlling the dispersion behaviour of two-dimensional nanomaterials using light as a clean and low energy external stimulus. Electronic supplementary information (ESI) available: Includes further details

  8. Effects of fluorinated and hydrogenated surfactants on human serum albumin at different pHs.

    PubMed

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

    2006-01-01

    Complexation between human serum albumin (HSA) and two different surfactants, one fully fluorinated (sodium perfluorooctanoate, SPFO) and one fully hydrogenated (sodium caprylate, SO), was studied using zeta-potential measurements and difference spectroscopy. The study was carried out at three different pHs, 3.2, 6.7, and 10.0. The spectroscopy study was performed at pHs 6.7 and 10.0, given that at pH 3.2 high turbidity was observed in the wide range of surfactant concentrations. The results were interpreted in terms of the electrostatic and hydrophobic contributions to the stability of the different phases formed in the water-surfactant-HSA system. Solutions and precipitates were observed in the concentration range investigated in more detail. Using Pace methods, the thermodynamic values of the surfactant-induced conformational changes in HSA were determined for sodium perfluorooctanoate in the concentration range 2-12 mmol dm(-3) at pH 6.7 and 5-22 mmol dm(-3) at pH 10.0. Electrophoretic measurements were used to characterize surfactant adsorption by determining the number of molecules adsorbed on the surface of HSA and the Gibbs energy of adsorption. Finally, the interactions between human serum albumin and other anionic surfactants studied by other authors were compared with those observed in the present work.

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

    PubMed

    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.

  10. Demulsification of emulsions produced from surfactant recovery operations and recovery of surfactants therefrom

    SciTech Connect

    Allison, J.B.; Kudchadker, M.V.; Whittington, L.E.

    1981-07-07

    Treatment of emulsions of oil and water produced from surfactant recovery operations whereby the produced emulsions containing surfactants are demulsified and the surfactants are recovered in the water phase.

  11. Adsorbed polyelectrolyte coatings decrease Fe(0) nanoparticle reactivity with TCE in water: conceptual model and mechanisms.

    PubMed

    Phenrat, Tanapon; Liu, Yueqiang; Tilton, Robert D; Lowry, Gregory V

    2009-03-01

    The surfaces of reactive nanoscale zerovalent iron (NZVI) particles used for in situ groundwater remediation are modified with polymers or polyelectrolytes to enhance colloidal stability and mobility in the subsurface. However, surface modification decreases NZVI reactivity. Here, the TCE dechlorination rate and reaction products are measured as a function of adsorbed polyelectrolyte mass for three commercially available polyelectrolytes used for NZVI surface modification including poly(styrene sulfonate) (PSS), carboxymethyl cellulose (CMC), and polyaspartate (PAP). The adsorbed mass, extended layer thickness, and TCE-polyelectrolyte partition coefficient are measured and used to explain the effect of adsorbed polyelectrolyte on NZVI reactivity. For all modifiers, the dechlorination rate constant decreased nonlinearly with increasing surface excess, with a maximum of a 24-fold decrease in reactivity. The TCE dechlorination pathways were not affected. Consistent with Scheutjens-Fleer theory for homopolymer adsorption, the nonlinear relationship between the dechlorination rate and the surface excess of adsorbed polyelectrolyte suggests that adsorbed polyelectrolyte decreases reactivity primarily by blocking reactive surface sites at low surface excess where they adsorb relatively flat onto the NZVI surface, and by a combination of site blocking and decreasing the aqueous TCE concentration at the NZVI surface due to partitioning of TCE to adsorbed polyelectrolytes. This explanation is also consistent with the effect of adsorbed polyelectrolyte on acetylene formation. This conceptual model should apply to other medium and high molecular weight polymeric surface modifiers on nanoparticles, and potentially to adsorbed natural organic matter.

  12. Interactions between polymers and surfactants

    SciTech Connect

    de Gennes, P.G. )

    1990-11-01

    A surfactant film (at the water/air interface, or in a bilayer) is exposed to a solution of a neutral, flexible, polymer. Depending on the interactions, and on the Langmuir pressure II of the pure surfactant film, the authors expected to find three types of behavior: (I) the polymer does not absorb; (II) the polymer absorbs and mixes with the surfactant; (III) the polymer absorbs but segregates from the surfactant. Their interest here is in case II. They predict that (a) bilayers become rigid; (b) bilayers, exposed to polymer on one side only, tend to bend strongly; (c) the surface viscosity of monolayers or bilayers is considerably increased; soap films or foams, which usually drain by turbulent (two-dimensional) flows, may be stabilized in case II.

  13. Sorption of linear alcohol ethoxylate surfactant homologs to soils

    NASA Astrophysics Data System (ADS)

    Yuan, Ching; Jafvert, Chad T.

    1997-11-01

    Sorption onto five saturated soils of the homologs within the commercial surfactant mixture Brij 35 (registered trademark of ICI Americas) was investigated. Brij 35 is a mixture of linear ethoxylated alcohols, having an average of 23 ethoxy (EO) groups per molecule and alcohol chain of primarily 12 carbons in length (C 12H 25(OCH 2CH 2) 23OH). In experiments, saturated soils were exposed to various concentrations of the surfactant mixture for specified times, the slurries were centrifuged to separate the phases, the aqueous phases were extracted with 1,2-dichloroethane, and the residual homologs were derivatized with 3,5-dinitrobenzoyl chloride and analyzed by normal phase HPLC. Homologs containing 4-43 EO groups were chromatographically separated at near baseline. At aqueous Brij 35 concentrations below the critical micelle concentration (cmc), the proportion of each homolog sorbed to each of the soils increased with increasing EO chain length through the homologous series. As a result, in experiments where a significant proportion of the surfactant adsorbed, significant shifts in the aqueous phase compositions occurred to mixtures with lower mean EO numbers. A sharp break in the adsorption isotherms occurs at the cmc.

  14. Reflectivity studies on adsorbed block copolymers under shear

    SciTech Connect

    Smith, G.S.; Wages, S.; Baker, S.M.; Toprakcioglu, C.; Hadziioannou, G.

    1994-12-01

    The authors report neutron reflectivity data on (poly)styrene-(poly)ethylene oxide (PS-PEO) diblock copolymers adsorbed onto quartz from the selective solvent cyclohexane (a non-solvent for PEO and a poor solvent for PS). The PEO ``anchor block`` adsorbs strongly to form a thin layer on the quartz substrate, while the deuterated PS chains dangle into the solvent. They find that under static conditions the density profile of the PS block in a poor solvent can be well described by a Schultz function which is indicative of a polymer ``mushroom.`` Furthermore, they have studied the same system under shear at shear rates from 0--400s{sup {minus}1}. They find that there is a dramatic increase in the thickness of the PS layer under shear in cyclohexane and that the relaxation time from the shear-on profile back to the static profile is on the order of several days.

  15. Amine-pillared Nanosheet Adsorbents for CO2 Capture Applications

    NASA Astrophysics Data System (ADS)

    Jiang, Hui

    Amine-functionalized solid adsorbents have gained attention within the last decade for their application in carbon dioxide capture, due to their many advantages such as low energy cost for regeneration, tunable structure, elimination of corrosion problems, and additional advantages. However, one of the challenges facing this technology is to accomplish both high CO 2 capture capacity along with high CO2 diffusion rates concurrently. Current amine-based solid sorbents such as porous materials similar to SBA-15 have large pores diffusion entering molecules; however, the pores become clogged upon amine inclusion. To meet this challenge, our group's solution involves the creation of a new type of material which we are calling-amino-pillared nanosheet (APN) adsorbents which are generated from layered nanosheet precursors. These materials are being proposed because of their unique lamellar structure which exhibits ability to be modified by organic or inorganic pillars through consecutive swelling and pillaring steps to form large mesoporous interlayer spaces. After the expansion of the layer space through swelling and pillaring, the large pore space can be functionalized with amine groups. This selective functionalization is possible by the choice of amine group introduced. Our choice, large amine molecules, do not access the micropore within each layer; however, either physically or chemically immobilized onto the surface of the mesoporous interlayer space between each layer. The final goal of the research is to investigate the ability to prepare APN adsorbents from a model nanoporous layered materials including nanosheets precursor material MCM-22(P) and nanoporous layered silicate material AMH-3. MCM-22(P) contains 2-dimensional porous channels, 6 membered rings (MB) openings perpendicular to the layers and 10 MB channels in the plane of the layers. However, the transport limiting openings (6 MB) to the layers is smaller than CO2 gas molecules. In contrast, AMH-3 has

  16. Supercritical fluid regeneration of adsorbents

    NASA Astrophysics Data System (ADS)

    Defilippi, R. P.; Robey, R. J.

    1983-05-01

    The results of a program to perform studies supercritical (fluid) carbon dioxide (SCF CO2) regeneration of adsorbents, using samples of industrial wastewaters from manufacturing pesticides and synthetic solution, and to estimate the economics of the specific wastewater treatment regenerations, based on test data are given. Processing costs for regenerating granular activated carbon GAC) for treating industrial wastewaters depend on stream properties and regeneration throughput.

  17. Accurate assessment of the biodegradation of cationic surfactants in activated sludge reactors (OECD TG 303A).

    PubMed

    Geerts, Roy; van Ginkel, Cornelis G; Plugge, Caroline M

    2015-08-01

    The continuous-fed activated sludge test (OECD TG 303A) was used to predict the removal of cationic surfactants from wastewater in activated sludge plants. However, a method to differentiate between adsorption and biodegradation is not provided in these guidelines. Assessment of removal by biodegradation was possible with analysis of the surfactant present in mixed liquid suspended solids in combination with a simple equation. This equation was derived from the mass balance of the activated sludge unit in steady state. The removal by biodegradation of decylamine, tetradecylamine, octadecylamine, dioctadecylmethylamine and dioctadecyldimethylammonium chloride that have different capacities to adsorb was >99.9%, >99.9%, 98.2%, 94.2%, and 69.0%, respectively. The total removal of all five cationic surfactants from the influent was ≥98.8%. The removal of octadecylamine spiked at different influent concentrations indicated first order kinetics. PMID:25913361

  18. Automated flow system for sildenafil enrichment using surfactant coated solid-phase with fluorescence detection.

    PubMed

    Wang, Chien Chun; Sombra, Lorena; Fernández, Liliana

    2012-08-30

    In this work, Amberlite XAD-1180 resin is used for on-line surfactant-mediated pre-concentration of sildenafil as a prior step for its fluorescent detection. In order to activate the column for sildenafil pre-concentration, the cationic surfactant (hexadecyltrimethylammoniunm bromide, HTAB) is adsorbed onto the resin. In these conditions, sildenafil is retained by HTAB-resin and then it is eluted with ethanol and analyzed by spectrofluorimetry. Drug-surfactant association produces a considerable fluorescence enhancement, increasing considerably the sensitivity of detection. Therefore, sildenafil can be pre-concentrated and quantitatively determined, with a detection limit of 0.2 ng mL(-1). The proposed method was successfully applied to the analysis of bulk drug, human urine, tablets, and local herbal medicine. Validation processes were performed by recovering studies and statistical analysis with satisfactory results.

  19. Enhanced perfume surface delivery to interfaces using surfactant surface multilayer structures.

    PubMed

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

    2016-01-01

    Enhanced surface delivery and retention of perfumes at interfaces are the keys to their more effective and efficient deployment in a wide range of home and personal care related formulations. It has been previously demonstrated that the addition of multivalent counterions, notably Ca(2+), induces multilayer adsorption at the air-water interface for the anionic surfactant, sodium dodecyl-6-benzenesulfonate, LAS-6. Neutron reflectivity, NR, measurements are reported here which demonstrate that such surfactant surface multilayer structures are a potentially promising vehicle for enhanced delivery of perfumes to interfaces. The data show that the incorporation of the model perfumes, phenylethanol, PE, and linalool, LL, into the surface multilayer structure formed by LAS-6/Ca(2+) results in the surface structures being retained up to relatively high perfume mole fractions. Furthermore the amount of perfume at the surface is enhanced by at least an order of magnitude, compared to that co-adsorbed with a surfactant monolayer.

  20. Size dependent fractal aggregation mediated through surfactant in silica nanoparticle solution

    NASA Astrophysics Data System (ADS)

    Kumar, Sugam; Aswal, V. K.; Kohlbrecher, J.

    2012-06-01

    Small-angle neutron scattering (SANS) has been used to study aggregation of anionic silica nanoparticles in presence of cationic surfactant (DTAB) in aqueous solution. The measurements were carried out for different sizes of nanoparticles (8.2, 16.4 and 26.4 nm) at fixed (1 wt%) nanoparticles and surfactant concentration. It is found that the adsorption of surfactant micelles on the silica nanoparticles leads to the aggregation of nanoparticles, which is characterized by a fractal structure. The number of adsorbed micelles on nanoparticle increases from 7 to 152 with the increase in the size of the nanoparticle from 8.2 to 26.4 nm, whereas interestingly the fractal dimension remains same. The aggregate morphology in these systems is expected to be governed by the diffusion limited aggregation.

  1. Enhanced perfume surface delivery to interfaces using surfactant surface multilayer structures.

    PubMed

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

    2016-01-01

    Enhanced surface delivery and retention of perfumes at interfaces are the keys to their more effective and efficient deployment in a wide range of home and personal care related formulations. It has been previously demonstrated that the addition of multivalent counterions, notably Ca(2+), induces multilayer adsorption at the air-water interface for the anionic surfactant, sodium dodecyl-6-benzenesulfonate, LAS-6. Neutron reflectivity, NR, measurements are reported here which demonstrate that such surfactant surface multilayer structures are a potentially promising vehicle for enhanced delivery of perfumes to interfaces. The data show that the incorporation of the model perfumes, phenylethanol, PE, and linalool, LL, into the surface multilayer structure formed by LAS-6/Ca(2+) results in the surface structures being retained up to relatively high perfume mole fractions. Furthermore the amount of perfume at the surface is enhanced by at least an order of magnitude, compared to that co-adsorbed with a surfactant monolayer. PMID:26409782

  2. Thermoreversible crystallization of charged colloids due to adsorption/desorption of ionic surfactants.

    PubMed

    Murakado, Ai; Toyotama, Akiko; Yamamoto, Masaaki; Nagano, Ryota; Okuzono, Tohru; Yamanaka, Junpei

    2016-03-01

    We report that charged colloids exhibit thermoreversible crystallization via the adsorption of ionic surfactants onto particle surfaces. Due to the temperature dependence of the adsorption quantity, the colloids crystallized upon cooling and melted upon heating. To clarify the influences of surfactant adsorption on the crystallization, polystyrene (PS) particles dispersed in ethylene glycol (EG)/water mixtures were employed, enabling continuous tuning of the adsorption quantity by changing the EG concentration. The thermoreversible crystallization/melting behavior was found to be mainly attributable to changes in the ionic strength of the medium resulting from variation in the concentration of the non-adsorbed ionic surfactant molecules with temperature. We expect that the present findings will be useful for fine control of colloidal crystallization and the further study of colloidal crystallization in low permittivity media.

  3. Surfactant-assisted Nanocasting Route for Synthesis of Highly Ordered Mesoporous Graphitic Carbon and Its Application in CO2 Adsorption

    PubMed Central

    Wang, Yangang; Bai, Xia; Wang, Fei; Qin, Hengfei; Yin, Chaochuang; Kang, Shifei; Li, Xi; Zuo, Yuanhui; Cui, Lifeng

    2016-01-01

    Highly ordered mesoporous graphitic carbon was synthesized from a simple surfactant-assisted nanocasting route, in which ordered mesoporous silica SBA-15 maintaining its triblock copolymer surfactant was used as a hard template and natural soybean oil (SBO) as a carbon precursor. The hydrophobic domain of the surfactant assisted SBO in infiltration into the template’s mesoporous channels. After the silica template was carbonized and removed, a higher yield of highly-ordered graphitic mesoporous carbon with rod-like morphology was obtained. Because of the improved structural ordering, the mesoporous carbon after amine modification could adsorb more CO2 compared with the amine-functionalized carbon prepared without the assistance of surfactant. PMID:27220563

  4. Surfactant-assisted Nanocasting Route for Synthesis of Highly Ordered Mesoporous Graphitic Carbon and Its Application in CO2 Adsorption

    NASA Astrophysics Data System (ADS)

    Wang, Yangang; Bai, Xia; Wang, Fei; Qin, Hengfei; Yin, Chaochuang; Kang, Shifei; Li, Xi; Zuo, Yuanhui; Cui, Lifeng

    2016-05-01

    Highly ordered mesoporous graphitic carbon was synthesized from a simple surfactant-assisted nanocasting route, in which ordered mesoporous silica SBA-15 maintaining its triblock copolymer surfactant was used as a hard template and natural soybean oil (SBO) as a carbon precursor. The hydrophobic domain of the surfactant assisted SBO in infiltration into the template’s mesoporous channels. After the silica template was carbonized and removed, a higher yield of highly-ordered graphitic mesoporous carbon with rod-like morphology was obtained. Because of the improved structural ordering, the mesoporous carbon after amine modification could adsorb more CO2 compared with the amine-functionalized carbon prepared without the assistance of surfactant.

  5. Stabilization of lamellar oil-water liquid crystals by surfactant/ co-surfactant monolayers

    NASA Astrophysics Data System (ADS)

    Braganza, L. F.; Dubois, M.; Tabony, J.

    1989-03-01

    LIQUID crystals are divided into two main classes, thermotropic and lyotropic. Thermotropic liquid crystals are formed by melting, whereas lyotropic liquid crystals arise from the association of molecules, such as soap and water, that in general are not in themselves liquid crystalline. Thermotropic liquid crystals are used for liquid-crystal displays; lyotropic liquid crystals occur in living cells. Here we report a novel sequence of lyotropic liquid crystals comprising alternate layers of oil and water whose thickness varies linearly with the relative proportions of oil and water, and we have determined their structure using neutron diffraction methods. The oil and water layers are separated and stabilized by a monolayer film of surfactant and co-surfactant. The individual layers are typically a hundred ångströms or more in thickness, and total lamellar spacings of up to 1,000 Å were observed. This behaviour is difficult to describe in terms of the theories of colloid stability currently used to describe lyotropic liquid crystals. An understanding of the self-organization of such systems over such large distances would elucidate how long-range liquid-crystalline ordering arises in living cells. Moreover, thermotropic liquid crystals are expensive and chemically relatively unstable, and lamellar mesophases of the lyotopic type described here could lead to inexpensive, chemically stable liquid-crystalline materials suitable for industrial application.

  6. Fluorescence probe studies of the effect of concentration on the state of aggregation of surfactants in aqueous solution

    SciTech Connect

    Lianos, P.; Zana, R.

    1981-11-01

    The results obtained in this study indicate that the aggregation numbers of a zwitterionic surfactant where the charges are well separated, and of various ionic surfactants, are independent of the surfactant concentration from the critical micelle concentration to ca. 0.3 M. In the absence of added salts these n values are consistent with the quasi-spherical oil drop model for micelles. The n values obtained for a zwitterionic surfactant where the 2 charges nearly neutralize each other and for a nonionic surfactant are large, and probably indicative of rod-like micelles. In addition the aggregation number for the nonionic surfactant has been found to increase with concentration, in the concentration range investigated. The values of the 14/13 ratio confirm that pyrene is solubilized preferentially in the micelle palisade layer rather than in the hydrophobic core. 41 references.

  7. Protein-nanoparticle interactions evaluation by immunomethods: Surfactants can disturb quantitative determinations.

    PubMed

    Fornaguera, Cristina; Calderó, Gabriela; Solans, Conxita; Vauthier, Christine

    2015-08-01

    The adsorption of proteins on nanoparticle surface is one of the first events that occur when nanoparticles enter in the blood stream, which influences nanoparticles lifetime and further biodistribution. Albumin, which is the most abundant protein in serum and which has been deeply characterized, is an interesting model protein to investigate nanoparticle-protein interactions. Therefore, the interaction of nanoparticles with serum albumin has been widely studied. Immunomethods were suggested for the investigation of adsorption isotherms because of their ease to quantify the non-adsorbed bovine serum albumin without the need of applying separation methods that could modify the balance between the adsorbed and non-adsorbed proteins. The present work revealed that this method should be applied with caution. Artifacts in the determination of free protein can be generated by the presence of surfactants such as polysorbate 80, widely used in the pharmaceutical and biomedical field, that are needed to preserve the stability of nanoparticle dispersions. It was shown that the presence of traces of polysorbate 80 in the dispersion leads to an overestimation of the amount of bovine serum albumin remaining free in the dispersion medium when determined by both radial immunodiffusion and rocket immunoelectrophoresis. However, traces of poloxamer 188 did not result in clear perturbed migrations. These methods are not appropriate to perform adsorption isotherms of proteins on nanoparticle dispersions containing traces of remaining free surfactant. They should only be applied on dispersions that are free of surfactant that is not associated with nanoparticles.

  8. Experimental characterization of adsorbed protein orientation, conformation, and bioactivity

    PubMed Central

    Thyparambil, Aby A.; Wei, Yang; Latour, Robert A.

    2015-01-01

    Protein adsorption on material surfaces is a common phenomenon that is of critical importance in many biotechnological applications. The structure and function of adsorbed proteins are tightly interrelated and play a key role in the communication and interaction of the adsorbed proteins with the surrounding environment. Because the bioactive state of a protein on a surface is a function of the orientation, conformation, and accessibility of its bioactive site(s), the isolated determination of just one or two of these factors will typically not be sufficient to understand the structure–function relationships of the adsorbed layer. Rather a combination of methods is needed to address each of these factors in a synergistic manner to provide a complementary dataset to characterize and understand the bioactive state of adsorbed protein. Over the past several years, the authors have focused on the development of such a set of complementary methods to address this need. These methods include adsorbed-state circular dichroism spectropolarimetry to determine adsorption-induced changes in protein secondary structure, amino-acid labeling/mass spectrometry to assess adsorbed protein orientation and tertiary structure by monitoring adsorption-induced changes in residue solvent accessibility, and bioactivity assays to assess adsorption-induced changes in protein bioactivity. In this paper, the authors describe the methods that they have developed and/or adapted for each of these assays. The authors then provide an example of their application to characterize how adsorption-induced changes in protein structure influence the enzymatic activity of hen egg-white lysozyme on fused silica glass, high density polyethylene, and poly(methyl-methacrylate) as a set of model systems. PMID:25708632

  9. Experimental characterization of adsorbed protein orientation, conformation, and bioactivity.

    PubMed

    Thyparambil, Aby A; Wei, Yang; Latour, Robert A

    2015-01-01

    Protein adsorption on material surfaces is a common phenomenon that is of critical importance in many biotechnological applications. The structure and function of adsorbed proteins are tightly interrelated and play a key role in the communication and interaction of the adsorbed proteins with the surrounding environment. Because the bioactive state of a protein on a surface is a function of the orientation, conformation, and accessibility of its bioactive site(s), the isolated determination of just one or two of these factors will typically not be sufficient to understand the structure-function relationships of the adsorbed layer. Rather a combination of methods is needed to address each of these factors in a synergistic manner to provide a complementary dataset to characterize and understand the bioactive state of adsorbed protein. Over the past several years, the authors have focused on the development of such a set of complementary methods to address this need. These methods include adsorbed-state circular dichroism spectropolarimetry to determine adsorption-induced changes in protein secondary structure, amino-acid labeling/mass spectrometry to assess adsorbed protein orientation and tertiary structure by monitoring adsorption-induced changes in residue solvent accessibility, and bioactivity assays to assess adsorption-induced changes in protein bioactivity. In this paper, the authors describe the methods that they have developed and/or adapted for each of these assays. The authors then provide an example of their application to characterize how adsorption-induced changes in protein structure influence the enzymatic activity of hen egg-white lysozyme on fused silica glass, high density polyethylene, and poly(methyl-methacrylate) as a set of model systems. PMID:25708632

  10. Size-dependent interaction of silica nanoparticles with different surfactants in aqueous solution.

    PubMed

    Kumar, Sugam; Aswal, Vinod K; Kohlbrecher, Joachim

    2012-06-26

    The size-dependent interaction of anionic silica nanoparticles with ionic (anionic and cationic) and nonionic surfactants has been studied using small-angle neutron scattering (SANS). The surfactants used are anionic sodium dodecyl sulfate (SDS), cationic dodecyltrimethyl ammonium bromide (DTAB), and nonionic decaoxyethylene n-dodecylether (C(12)E(10)). The measurements have been carried out for three different sizes of silica nanoparticles (8, 16, and 26 nm) at fixed concentrations (1 wt % each) of nanoparticles and surfactants. It is found that irrespective of the size of the nanoparticles there is no significant interaction evolved between like-charged nanoparticles and the SDS micelles leading to any structural changes. However, the strong attraction of oppositely charged DTAB micelles with silica nanoparticles results in the aggregation of nanoparticles. The number of micelles mediating the nanoparticle aggregation increases with the size of the nanoparticle. The aggregates are characterized by fractal structure where the fractal dimension is found to be constant (D ≈ 2.3) independent of the size of the nanoparticles and consistent with diffusion-limited-aggregation-type fractal morphology in these systems. In the case of nonionic surfactant C(12)E(10), micelles interact with the individual silica nanoparticles. The number of adsorbed micelles per nanoparticle increases drastically whereas the percentage of adsorbed micelles on nanoparticles decreases with the increase in the size of the nanoparticles. PMID:22655980

  11. Comparison of the adsorption of linear alkanesulfonate and linear alkylbenzenesulfonate surfactants at liquid interfaces

    SciTech Connect

    Watry, M.R.; Richmond, G.L.

    2000-02-09

    Linear alkanesulfonates and linear alkylbenzenesulfonates constitute a large fraction of the surfactants used in commercial detergents and cleansers. Despite the industrial significance and the possible environmental impact of these compounds, very little in known regarding the molecular properties of these compounds and how they relate to macroscopic properties desired in applications. This study employs vibrational sum frequency spectroscopy (VSFS) to examine and compare the molecular structure of surfactants in these two classes as they adsorb at organic/water and air/water interfaces. The linear alkane- and alkylbenzenesulfonates studied are, respectively, dodecanesulfonate and dodecylbenzenesulfonate. By measurement and comparison of the vibrational spectra of these adsorbed surfactants, changes in the orientation of the aromatic ring and the conformation of the alkyl chains are examined as a function on the number density of surfactant molecules at the interface. The change in aromatic ring orientation as a function of surface concentration is quite different for the dodecylbenzenesulfonate at the air/water interface relative to that at the organic/water interface (CCl{sub 4}/water). The alkyl chains of the dodecylbenzenesulfonate are highly disordered at both interfaces as a function of interfacial concentration, in stark contrast to what is observed for the dodecanesulfonate. The results are discussed in terms of the disruptive nature of the benzene ring and the higher degree of hydrophobicity of the alkyl chain relative to the benzene ring near the ionic sulfonate group.

  12. Surfactant assisted growth of MgO films on GaN

    SciTech Connect

    Paisley, E. A.; Shelton, T. C.; Collazo, R.; Sitar, Z.; Maria, J.-P.; Christen, H. M.; Biegalski, M. D.; Mita, S.

    2012-08-27

    Thin epitaxial films of <111> oriented MgO on [0001]-oriented GaN were grown by molecular beam epitaxy and pulsed laser deposition using the assistance of a vapor phase surfactant. In both cases, surfactant incorporation enabled layer-by-layer growth and a smooth terminal surface by stabilizing the {l_brace}111{r_brace} rocksalt facet. Metal-insulator-semiconductor capacitor structures were fabricated on n-type GaN. A comparison of leakage current density for conventional and surfactant-assisted growth reveals a nearly 100 Multiplication-Sign reduction in leakage current density for the surfactant-assisted samples. These data verify numerous predictions regarding the role of H-termination in regulating the habit of rocksalt crystals.

  13. Biomimicry of surfactant protein C.

    PubMed

    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

  14. Enhanced removal of nitrate from water using surface modification of adsorbents--a review.

    PubMed

    Loganathan, Paripurnanda; Vigneswaran, Saravanamuthu; Kandasamy, Jaya

    2013-12-15

    Elevated concentration of nitrate results in eutrophication of natural water bodies affecting the aquatic environment and reduces the quality of drinking water. This in turn causes harm to people's health, especially that of infants and livestock. Adsorbents with the high capacity to selectively adsorb nitrate are required to effectively remove nitrate from water. Surface modifications of adsorbents have been reported to enhance their adsorption of nitrate. The major techniques of surface modification are: protonation, impregnation of metals and metal oxides, grafting of amine groups, organic compounds including surfactant coating of aluminosilicate minerals, and heat treatment. This paper reviews current information on these techniques, compares the enhanced nitrate adsorption capacities achieved by the modifications, and the mechanisms of adsorption, and presents advantages and drawbacks of the techniques. Most studies on this subject have been conducted in batch experiments. These studies need to include continuous mode column trials which have more relevance to real operating systems and pilot-plant trials. Reusability of adsorbents is important for economic reasons and practical treatment applications. However, only limited information is available on the regeneration of surface modified adsorbents. PMID:24211565

  15. Enhanced removal of nitrate from water using surface modification of adsorbents--a review.

    PubMed

    Loganathan, Paripurnanda; Vigneswaran, Saravanamuthu; Kandasamy, Jaya

    2013-12-15

    Elevated concentration of nitrate results in eutrophication of natural water bodies affecting the aquatic environment and reduces the quality of drinking water. This in turn causes harm to people's health, especially that of infants and livestock. Adsorbents with the high capacity to selectively adsorb nitrate are required to effectively remove nitrate from water. Surface modifications of adsorbents have been reported to enhance their adsorption of nitrate. The major techniques of surface modification are: protonation, impregnation of metals and metal oxides, grafting of amine groups, organic compounds including surfactant coating of aluminosilicate minerals, and heat treatment. This paper reviews current information on these techniques, compares the enhanced nitrate adsorption capacities achieved by the modifications, and the mechanisms of adsorption, and presents advantages and drawbacks of the techniques. Most studies on this subject have been conducted in batch experiments. These studies need to include continuous mode column trials which have more relevance to real operating systems and pilot-plant trials. Reusability of adsorbents is important for economic reasons and practical treatment applications. However, only limited information is available on the regeneration of surface modified adsorbents.

  16. Method And Apparatus For Regenerating Nox Adsorbers

    DOEpatents

    Driscoll, J. Joshua; Endicott, Dennis L.; Faulkner, Stephen A.; Verkiel, Maarten

    2006-03-28

    Methods and apparatuses for regenerating a NOx adsorber coupled with an exhaust of an engine. An actuator drives a throttle valve to a first position when regeneration of the NOx adsorber is desired. The first position is a position that causes the regeneration of the NOx adsorber. An actuator drives the throttle valve to a second position while regeneration of the NOx adsorber is still desired. The second position being a position that is more open than the first position and operable to regenerate a NOx adsorber.

  17. Ionic Surfactant Binding to pH-Responsive Polyelectrolyte Brush-Grafted Nanoparticles in Suspension and on Charged Surfaces.

    PubMed

    Riley, John K; An, Junxue; Tilton, Robert D

    2015-12-29

    The interactions between silica nanoparticles grafted with a brush of cationic poly(2-(dimethylamino) ethyl methacrylate) (SiO2-g-PDMAEMA) and anionic surfactant sodium dodecyl sulfate (SDS) is investigated by dynamic light scattering, electrophoretic mobility, quartz crystal microbalance with dissipation, ellipsometry, and atomic force microscopy. SiO2-g-PDMAEMA exhibits pH-dependent charge and size properties which enable the SDS binding to be probed over a range of electrostatic conditions and brush conformations. SDS monomers bind irreversibly to SiO2-g-PDMAEMA at low surfactant concentrations (∼10(-4) M) while exhibiting a pH-dependent threshold above which cooperative, partially reversible SDS binding occurs. At pH 5, SDS binding induces collapse of the highly charged and swollen brush as observed in the bulk by DLS and on surfaces by QCM-D. Similar experiments at pH 9 suggest that SDS binds to the periphery of the weakly charged and deswollen brush and produces SiO2-g-PDMAEMA/SDS complexes with a net negative charge. SiO2-g-PDMAEMA brush collapse and charge neutralization is further confirmed by colloidal probe AFM measurements, where reduced electrosteric repulsions and bridging adhesion are attributed to effects of the bound SDS. Additionally, sequential adsorption schemes with SDS and SiO2-g-PDMAEMA are used to enhance deposition relative to SiO2-g-PDMAEMA direct adsorption on silica. This work shows that the polyelectrolyte brush configuration responds in a more dramatic fashion to SDS than to pH-induced changes in ionization, and this can be exploited to manipulate the structure of adsorbed layers and the corresponding forces of compression and friction between opposing surfaces.

  18. Nonlinear vibrational spectroscopy of surfactants at liquid interfaces

    NASA Astrophysics Data System (ADS)

    Miranda, Paulo Barbeitas

    solid/liquid interface. It is shown that the conformation of a monolayer adsorbed onto a solid substrate and immersed in a liquid is highly dependent on the monolayer surface density and on the nature of intermolecular interactions in the liquid. Fully packed monolayers are well ordered in any environment due to strong surfactant-surfactant interactions and limited liquid penetration into the monolayer. In contrast, loosely packed monolayers are very sensitive to the liquid environment. Non-polar liquids cause a mild increase in the surfactant conformational disorder. Polar liquids induce more disorder and hydrogen-bonding liquids produce highly disordered conformations due to the hydrophobic effect. When immersed in alkanes, under certain conditions the surfactant chains may become highly ordered due to their interaction with the liquid molecules (chain-chain interaction). In the case of long-chain alcohols, competition between the hydrophobic effect and chain-chain interaction is observed.

  19. Surfactant for pediatric acute lung injury.

    PubMed

    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.

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

    PubMed

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

    2014-10-01

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

  1. Mixed Surfactant Solutions for the Dispersion of Multiwalled Carbon Nanotubes and the Study of Their Antibacterial Activity.

    PubMed

    Bai, Yu; Gao, Jingjiun; Wang, Cunyang; Zhang, Rui; Ma, Wen

    2016-03-01

    The dispersibility of mixed surfactant-modified multiwalled carbon nanotubes (MWNTs) and their effect on antibacterial activity were examined. The ratio of 9:1 between sodium dodecyl benzene-sulfate (SDBS) and hexadecyltrimethylammonium bromide (CTAB) showed the highest dispersing power for MWNTs. The use of mixed surfactants enabled the MWNTs to form a stable dispersion at a lower total surfactant concentration than their concentrations when used alone. UV-vis spectroscopy, transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the dispersion of MWNTs in the aqueous phase. The results indicated that the surfactant molecules had been successfully adsorbed onto the surface of the MWNTs. The mixed surfactant-modified MWNTs exhibited a strong antibacterial activity and concentration dependence to Staphylococcus aureus (S. aureus). Based on the considerations of the cost and environmental impact, the use of mixed surfactants (SDBS-CTAB) should be more favorable for the stable dispersion of MWNTs and the improvement of antibacterial activity than the use of a single surfactant.

  2. In situ modification of chromatography adsorbents using cold atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Olszewski, P.; Willett, T. C.; Theodosiou, E.; Thomas, O. R. T.; Walsh, J. L.

    2013-05-01

    Efficient manufacturing of increasingly sophisticated biopharmaceuticals requires the development of new breeds of chromatographic materials featuring two or more layers, with each layer affording different functions. This letter reports the in situ modification of a commercial beaded anion exchange adsorbent using atmospheric pressure plasma generated within gas bubbles. The results show that exposure to He-O2 plasma in this way yields significant reductions in the surface binding of plasmid DNA to the adsorbent exterior, with minimal loss of core protein binding capacity; thus, a bi-layered chromatography material exhibiting both size excluding and anion exchange functionalities within the same bead is produced.

  3. Hydraulic properties of adsorbed water films in unsaturated porous media

    SciTech Connect

    Tokunaga, Tetsu K.

    2009-03-01

    Adsorbed water films strongly influence residual water saturations and hydraulic conductivities in porous media at low saturations. Hydraulic properties of adsorbed water films in unsaturated porous media were investigated through combining Langmuir's film model with scaling analysis, without use of any adjustable parameters. Diffuse double layer influences are predicted to be important through the strong dependence of adsorbed water film thickness (f) on matric potential ({Psi}) and ion charge (z). Film thickness, film velocity, and unsaturated hydraulic conductivity are predicted to vary with z{sup -1}, z{sup -2}, and z{sup -3}, respectively. In monodisperse granular media, the characteristic grain size ({lambda}) controls film hydraulics through {lambda}{sup -1} scaling of (1) the perimeter length per unit cross sectional area over which films occur, (2) the critical matric potential ({Psi}{sub c}) below which films control flow, and (3) the magnitude of the unsaturated hydraulic conductivity when {Psi} < {Psi}{sub c}. While it is recognized that finer textured sediments have higher unsaturated hydraulic conductivities than coarser sands at intermediate {Psi}, the {lambda}{sup -1} scaling of hydraulic conductivity predicted here extends this understanding to very low saturations where all pores are drained. Extremely low unsaturated hydraulic conductivities are predicted under adsorbed film-controlled conditions (generally < 0.1 mm y{sup -1}). On flat surfaces, the film hydraulic diffusivity is shown to be constant (invariant with respect to {Psi}).

  4. Three stage multilayer formation kinetics during adsorption of an anionic fluorinated surfactant onto germanium: solution pH and salt effects.

    PubMed

    Xing, Rong; Rankin, Stephen E

    2013-07-01

    The effects of solution pH, salt type and its concentration on the adsorption kinetics and the structural evolution of an anionic fluorinated surfactant, tetraethylammonium perfluorooctylsulfonate (TEA-FOS), at the hydroxylated Ge/aqueous solution interface are investigated by using Fourier transform infrared spectroscopy in attenuated total reflection mode (ATR-FTIR). The surface excess, the adsorption rate, the durations of three-stage adsorption and the molecular orientation of adsorbed TEA-FOS are all dependent on the pH of the solution. Consistent with the expected effects of solution pH on surface charge of the germanium oxide crystal surface, the most surfactant adsorbs at acidic pH 3.4 although a considerable amount still adsorbs at pH 10.0. Linear dichroism measurements suggest that the adsorbed surfactants prefer to form less-curved (flattened) multilayer admicelles, which pack more closely on the solid surface as the solution pH decreases. Under both acidic (pH 3.4) and basic (pH 10.0) conditions, the equilibrium surface excess first passes through a maximum as NaCl concentration increases, followed by a decrease. This suggests that excessive NaCl concentration is not favorable for multilayer formation due to increased electrostatic shielding which reduces the ion-pairing ability between TEA(+) and FOS(-). In addition, infrared dichroism measurements of CF2 stretching show that salt type and its concentration influence the structural evolution of adsorbed surfactants. A moderate amount of NaCl favors the assembly of adsorbed micelles into ordered flattened aggregates, but an excess of NaCl makes adsorbed surfactants assemble randomly like spherical aggregates. Compared to Na(+) and K(+) ions, Ca(2+) ions cause the adsorbed surfactants to pack more closely on the solid surface into flattened micellar aggregates. All of the effects of solution pH and salt can be rationalized based on Coulombic interactions between the substrate surface, surfactants and

  5. Lessons from the biophysics of interfaces: lung surfactant and tear fluid.

    PubMed

    Rantamäki, Antti H; Telenius, Jelena; Koivuniemi, Artturi; Vattulainen, Ilpo; Holopainen, Juha M

    2011-05-01

    The purpose of this review is to provide insight into the biophysical properties and functions of tear fluid and lung surfactant--two similar fluids covering the epithelium of two distinctive organs. Both fluids form a layer-like structure that essentially comprise of an aqueous layer next to the epithelium and an anterior lipid layer at the air-water interface. The aqueous layers contain soluble proteins and metabolites, and they are responsible for the host defence system and nutrition of the organ. However, many proteins also interact with the lipid layer and are important for the surface-active function of the fluid film. The lipid layer of lung surfactant comprises mainly of phospholipids, especially phosphatidylcholines, and only small amounts of non-polar lipids, mainly cholesterol. In contrast, tear fluid lipid layer comprises of a mixture of polar and non-polar lipids. However, the relative proportion and the spectrum of different polar and non-polar lipids seem to be more extensive in tear fluid than in lung surfactant. The differing lipid compositions generate distinctive lipid layer structures. Despite the structural differences, these lipid layers decrease the surface tension of the air-water interface. The structure of the tear film lipid layer also minimises the evaporation of the tear fluid. In lung surfactant surface activity is crucial for the function of the organ, as the lipid layer prevents the collapse of the lung alveoli during the compression-expansion cycle of breathing. Similarly the tear film experiences a compression-expansion cycle during blinking. The dynamics of this cycle have been studied to a lesser extent and are not as clear as those of lung surfactant. The common structure and properties suggest a similar behaviour under rapid compression-expansion for both fluids. PMID:21352946

  6. Inorganic dual-layer microporous supported membranes

    DOEpatents

    Brinker, C. Jeffrey; Tsai, Chung-Yi; Lu, Yungfeng

    2003-03-25

    The present invention provides for a dual-layer inorganic microporous membrane capable of molecular sieving, and methods for production of the membranes. The inorganic microporous supported membrane includes a porous substrate which supports a first inorganic porous membrane having an average pore size of less than about 25 .ANG. and a second inorganic porous membrane coating the first inorganic membrane having an average pore size of less than about 6 .ANG.. The dual-layered membrane is produced by contacting the porous substrate with a surfactant-template polymeric sol, resulting in a surfactant sol coated membrane support. The surfactant sol coated membrane support is dried, producing a surfactant-templated polymer-coated substrate which is calcined to produce an intermediate layer surfactant-templated membrane. The intermediate layer surfactant-templated membrane is then contacted with a second polymeric sol producing a polymeric sol coated substrate which is dried producing an inorganic polymeric coated substrate. The inorganic polymeric coated substrate is then calcined producing an inorganic dual-layered microporous supported membrane in accordance with the present invention.

  7. Sand sorption process for the removal of sodium dodecyl sulfate (anionic surfactant) from water.

    PubMed

    Khan, M Nasiruddin; Zareen, Uzma

    2006-05-20

    Granite sand was used to adsorb anionic surfactant, sodium dodecyl sulfate (SDS) from water at natural pH 6.25. The effect of adsorbent size, pH, temperature and amount of adsorbent has been examined. The results indicate that the Langmuir model provides the best correlation of experimental data. Thermodynamic parameters like entropy, enthalpy and free energy of adsorption were evaluated. Decreasing the temperature accelerates the adsorption of SDS onto sand surface. The kinetic data were analyzed by using pseudo-first order Lagergren equation. Adsorption of SDS was exothermic and dominated by physisorption with activation energy (Ea) 33.65 kJ mol(-1). In addition, regeneration of granite sand by washing with Fenton likes reagent was examined. The results suggested that granite sand is suitable as a sorbent material for recovery and adsorption of SDS from aqueous solutions in view of its effectiveness and cheaper cost.

  8. Insoluble layer deposition and dilatational rheology at a microscale spherical cap interface.

    PubMed

    Kotula, Anthony P; Anna, Shelley L

    2016-08-17

    The dilatational properties of insoluble monolayers are important for understanding the mechanics of biological systems and consumer products, but isolating the dilatational response of an interface is challenging due to the difficulties in separating dilatation from shear and other deformation modes. Oscillations of a microscale bubble radius are useful for generating purely dilatational flows, but the current deposition methods for insoluble layers onto fluid interfaces are not easily scaled down. In this paper, we describe a miscible solvent exchange procedure for generating insoluble layers at an air-water interface pinned at the tip of a capillary tens of micrometers in diameter. We show that the amount of surfactant adsorbed at the interface can be controlled by the initial concentration dissolved in isopropanol (the starting solvent) and the volumetric flow rate of solvent exchange. Surface pressure-area isotherms and dilatational moduli are measured concurrently for three insoluble surfactants: palmitic acid (PA), dimyristoylphosphatidylcholine (DMPC) and dipalmitoylphosphatidylcholine (DPPC). The isotherms measured on the microscale interface compare well with previous experiments performed on a Langmuir trough. However, the magnitudes of the dilatational moduli differ from those measured on either Langmuir trough or pendant drop apparatuses. Several possible reasons for the observed differences are discussed. A comparison of the dilatational modulus with the Gibbs elasticity is used to determine the presence of dilatational extra stresses at the interface. The isotherm and dilatational modulus of the insoluble component of the industrial surfactant Tween 80 are measured using this approach. The methods developed here also open the possibility for future study of the important role of finite size effects on microstructure formation and the resulting interfacial mechanics.

  9. Insoluble layer deposition and dilatational rheology at a microscale spherical cap interface.

    PubMed

    Kotula, Anthony P; Anna, Shelley L

    2016-08-17

    The dilatational properties of insoluble monolayers are important for understanding the mechanics of biological systems and consumer products, but isolating the dilatational response of an interface is challenging due to the difficulties in separating dilatation from shear and other deformation modes. Oscillations of a microscale bubble radius are useful for generating purely dilatational flows, but the current deposition methods for insoluble layers onto fluid interfaces are not easily scaled down. In this paper, we describe a miscible solvent exchange procedure for generating insoluble layers at an air-water interface pinned at the tip of a capillary tens of micrometers in diameter. We show that the amount of surfactant adsorbed at the interface can be controlled by the initial concentration dissolved in isopropanol (the starting solvent) and the volumetric flow rate of solvent exchange. Surface pressure-area isotherms and dilatational moduli are measured concurrently for three insoluble surfactants: palmitic acid (PA), dimyristoylphosphatidylcholine (DMPC) and dipalmitoylphosphatidylcholine (DPPC). The isotherms measured on the microscale interface compare well with previous experiments performed on a Langmuir trough. However, the magnitudes of the dilatational moduli differ from those measured on either Langmuir trough or pendant drop apparatuses. Several possible reasons for the observed differences are discussed. A comparison of the dilatational modulus with the Gibbs elasticity is used to determine the presence of dilatational extra stresses at the interface. The isotherm and dilatational modulus of the insoluble component of the industrial surfactant Tween 80 are measured using this approach. The methods developed here also open the possibility for future study of the important role of finite size effects on microstructure formation and the resulting interfacial mechanics. PMID:27478885

  10. Waterflooding employing mixtures of sulfonate surfactants

    SciTech Connect

    Savins, J.G.; Waite, J.M.; Burdyn, R.F.

    1980-11-04

    A new waterflooding process is described in which at least a portion of the injected fluid comprises a viscous aqueous liquid having a monovalent salt salinity within the range of 1.5 to 4.0% by wt and containing first and second sulfonate surfactants. The first surfactant is a petroleum sulfonate having a relatively broad molecular weight distribution and the second surfactant is a synthetic alkyl or alkylaryl sulfonate having a molecular weight distribution narrower than that of the first surfactant. The first and second surfactants are present in the aqueous liquid in relative amounts such that the ratio of the concentration of the first surfactant to the concentration of the second surfactant is within the range of 1:3 to 1:1. The thickened aqueous liquid containing the above described multicomponent surfactant system also contains a water-soluble C3-C6 aliphatic alcohol. 11 claims.

  11. Surfactant enhanced removal of PCE in a nominally two-dimensional, saturated, stratified porous medium

    NASA Astrophysics Data System (ADS)

    Walker, R. C.; Hofstee, C.; Dane, J. H.; Hill, W. E.

    1998-10-01

    Although surfactant enhanced remediation of nonaqueous phase liquids (NAPLs) by pump-and-treat technology has been studied extensively in the laboratory with one-dimensional columns, very few multi-dimensional investigations have been reported. In this study we focus on the removal of perchloroethylene (PCE) from a two-dimensional, saturated porous medium containing a low permeability sand layer situated in an otherwise high permeability sand. A PCE spill was applied at the surface of the porous medium and allowed to redistribute until static equilibrium was achieved. The porous medium was then flushed with various surfactant and co-solvent formulations injected at the PCE source location and extracted at the bottom of the porous medium using a configuration similar to that of Abdul and Ang [Abdul, S.A., Ang, C.C., 1994. In situ surfactant washing of polychlorinated biphenyls and oils from a contaminated field site: Phase II. Pilot study. Ground Water 32, 727-734]. Effluent samples were analyzed for dissolved PCE concentrations. Volumetric water and PCE content values were determined at a number of locations by means of dual-energy gamma radiation measurements. Once surfactant flushing had started, PCE moved as a distinct separate phase ahead of the surfactant front. Most of this downward moving PCE accumulated on top of the low permeability sand layer. Some PCE, however, passed quickly through this layer and subsequently through the high permeability sand below it. Movement of some of the PCE into and through the low permeability sand layer was attributed to local heterogeneities combined with reduced interfacial tensions associated with the surfactant formulation. Clean-up of PCE in most of the high permeability sand was considered to be effective. PCE accumulated on top of the fine layer, however, posed a significant challenge to remediation and required several pumping configurations and surfactant/co-solvent formulations before most of it was removed.

  12. Biofoams and natural protein surfactants

    PubMed Central

    Cooper, Alan; Kennedy, Malcolm W.

    2010-01-01

    Naturally occurring foam constituent and surfactant proteins with intriguing structures and functions are now being identified from a variety of biological sources. The ranaspumins from tropical frog foam nests comprise a range of proteins with a mixture of surfactant, carbohydrate binding and antimicrobial activities that together provide a stable, biocompatible, protective foam environment for developing eggs and embryos. Ranasmurfin, a blue protein from a different species of frog, displays a novel structure with a unique chromophoric crosslink. Latherin, primarily from horse sweat, but with similarities to salivary, oral and upper respiratory tract proteins, illustrates several potential roles for surfactant proteins in mammalian systems. These proteins, together with the previously discovered hydrophobins of fungi, throw new light on biomolecular processes at air–water and other interfaces. This review provides a perspective on these recent findings, focussing on structure and biophysical properties. PMID:20615601

  13. Role of an amide bond for self-assembly of surfactants.

    PubMed

    Bordes, Romain; Tropsch, Juergen; Holmberg, Krister

    2010-03-01

    Self-assembly in solution and adsorption at the air-water interface and at solid surfaces were investigated for two amino-acid-based surfactants with conductimetry, NMR, tensiometry, quartz crystal microbalance with monitoring of the dissipation (QCM-D), and surface plasmon resonance (SPR). The surfactants studied were sodium N-lauroylglycinate and sodium N-lauroylsarcosinate, differing only in a methyl group on the amide nitrogen for the sarcosinate. Thus, the glycinate but not the sarcosinate surfactant is capable of forming intermolecular hydrogen bonds via the amide group. It was found that the amide bond, N-methylated or not, gave a substantial contribution to the hydrophilicity of the amphiphile. The ability to form intermolecular hydrogen bonds led to tighter packing at the air-water interface and at a hydrophobic surface. It also increased the tendency for precipitation as an acid-soap pair on addition of acid. Adsorption of the surfactants at a gold surface was also investigated and gave unexpected results. The sarcosine-based surfactant seemed to give bilayer adsorption, while the glycine derivative adsorbed as a monolayer.

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

    PubMed

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

    2014-11-18

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

  15. Adsorption of a cationic surfactant by a magsorbent based on magnetic alginate beads.

    PubMed

    Obeid, Layaly; El Kolli, Nadia; Dali, Noëlle; Talbot, Delphine; Abramson, Sébastien; Welschbillig, Mathias; Cabuil, Valérie; Bée, Agnès

    2014-10-15

    Adsorption of cetylpyridinium chloride (CPC), a cationic surfactant, by magnetic alginate beads (MagAlgbeads) was investigated. The magnetic adsorbent (called magsorbent) was prepared by encapsulation of magnetic functionalized nanoparticles in an alginate gel. The influence on CPC adsorption of several parameters such as contact time, pH and initial surfactant concentration was studied. The equilibrium isotherm shows that adsorption occurs through both electrostatic interactions with charge neutralization of the carboxylate groups of the beads and hydrophobic interactions inducing the formation of surfactant aggregates in the beads. The dosage of calcium ions released in the solution turns out to be a useful tool for understanding the adsorption mechanisms. Adsorption is accompanied by a shrinking of the beads that corresponds to a 45% reduction of the volume. Adsorption kinetic experiments show that equilibrium time is strongly dependent on the surfactant concentration, which monitors the nature of the interactions. On the other hand, since the pH affects the ionization state of adsorption sites, adsorption depends on the pH solution, maximum adsorption being obtained in a large pH range (3.2-12) in agreement with the pKa value of alginate (pKa=3.4-4.2). Finally, due to the formation of micelle-like surfactants aggregates in the magnetic alginate beads, they could be used as a new efficient magsorbent for hydrophobic pollutants. PMID:25086393

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

    PubMed

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

    2014-11-18

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

  17. Parametric analysis of surfactant-aided imbibition in fractured carbonates.

    PubMed

    Adibhatla, B; Mohanty, K K

    2008-01-15

    Many carbonate oil reservoirs are oil-wet and fractured; waterflood recovery is very low. Dilute surfactant solution injection into the fractures can improve oil production from the matrix by altering the wettability of the rock to a water-wetting state. A 2D, two-phase, multicomponent, finite-volume, fully-implicit numerical simulator calibrated with our laboratory results is used to assess the sensitivity of the process to wettability alteration, IFT reduction, oil viscosity, surfactant diffusivity, matrix block dimensions, and permeability heterogeneity. Capillarity drives the oil production at the early stage, but gravity is the major driving force afterwards. Surfactants which alter the wettability to a water-wet regime give higher recovery rates for higher IFT systems. Surfactants which cannot alter wettability give higher recovery for lower IFT systems. As the wettability alteration increases the rate of oil recovery increases. Recovery rate decreases with permeability significantly for a low tension system, but only mildly for high tension systems. Increasing the block dimensions and increasing oil viscosity decreases the rate of oil recovery and is in accordance with the scaling group for a gravity driven process. Heterogeneous layers in a porous medium can increase or decrease the rate of oil recovery depending on the permeability and the aspect ratio of the matrix block.

  18. ABC copolymer silicone surfactant templating for biomimetic silicification.

    PubMed

    Sun, Bo; Guo, Caiyun; Yao, Yuan; Che, Shunai

    2012-07-15

    Using the ABC copolymer silicone surfactant polydimethylsiloxane (PDMS)-graft-(polyethylene oxide (PEO)-block-propylene oxide (PPO)) (PSEP, Scheme 1a) as a template and tetraethoxysilane (TEOS) as a silica source, silica particles with various structures and morphologies (i.e., disordered spherical micellar aggregation, two-dimensional p6mm mesostructure, asymmetric multi-layer non-equilibrium vesicles and symmetric monolayer vesicles) were synthesized by changing the synthesis temperature from 30 to 80 °C. Increasing the hydrophobicity of the surfactant by increasing the temperature resulted in an increase in the surfactant packing parameter g, which led to the mesophase transformation from micellar to cylinder and later to a lamellar structure. The good compatibility between the PDMS and the TEOS, the different natures of the hydrophobic PDMS and PPO segments, and the hydrolysis and condensation rates of TEOS enabled the variation of silicification structures. This novel silicone surfactant templating route and a new type of materials with highly ordered mesostructures and asymmetric morphologies provide a new insight into the molecular factors governing inorganic-organic mesophase and biosilicification for fabricating functionalized materials.

  19. Structural features of polymer adsorbent LiChrolut EN and interfacial behavior of water and water/organic mixtures.

    PubMed

    Gun'ko, V M; Turov, V V; Zarko, V I; Nychiporuk, Y M; Goncharuk, E V; Pakhlov, E M; Yurchenko, G R; Kulik, T V; Palyanytsya, B B; Borodavka, T V; Krupskaya, T V; Leboda, R; Skubiszewska-Zieba, J; Osovskii, V D; Ptushinskii, Y G; Turov, A V

    2008-07-01

    The structural and adsorption characteristics of polymer adsorbent LiChrolut EN and the behavior of adsorbed water and water/organic mixtures were studied using adsorption, microcalorimetry, transmission and scanning electron microscopy, mass spectrometry, infrared spectroscopy, 1H NMR spectroscopy with layer-by-layer freezing-out of liquids (190-273 K), and thermally stimulated depolarization current method (90-265 K). This adsorbent is characterized by large specific surface area (approximately 1500 m2/g) and pore volume (0.83 cm3/g) with a major contribution of narrow pores (R<10 nm) of a complicated shape (long hysteresis loop is in nitrogen adsorption-desorption isotherm). The adsorbent includes aromatic and aliphatic structures and oxygen-containing functionalities and can effectively adsorb organics and water/organic mixtures. On co-adsorption of water and organics (dimethyl sulfoxide, chloroform, methane), there is a weak influence of one on another adsorbate due to their poor mixing in pores. Weakly polar chloroform displaces a fraction of water from narrow pores. These effects can explain high efficiency of the adsorbent in solid-phase extraction of organics from aqueous solutions. The influence of structural features of several carbon and polymer adsorbents on adsorbed nitrogen, water and water/organics is compared on the basis of the adsorption and 1H NMR data. PMID:18440015

  20. SURFACTANT ENHANCED AQUIFER REMEDIATION WITH SURFACTANT REGENERATION/REUSE

    EPA Science Inventory

    A demonstration of surfactant-enhanced aquifer remediation was conducted during the spring of 1999 at Marine Corps Base, Camp LeJeune, NC. A PCE-DNAPL zone was identified and delineated by extensive soil sampling in 1997, and was further characteized by a partitioning interwell t...

  1. A novel fiber-based adsorbent technology

    SciTech Connect

    Reynolds, T.A.

    1997-10-01

    In this Phase I Small Business Innovation Research program, Chemica Technologies, Inc. is developing an economical, robust, fiber-based adsorbent technology for removal of heavy metals from contaminated water. The key innovation is the development of regenerable adsorbent fibers and adsorbent fiber cloths that have high capacity and selectivity for heavy metals and are chemically robust. The process has the potential for widespread use at DOE facilities, mining operations, and the chemical process industry.

  2. Adsorbate-induced curvature and stiffening of graphene.

    PubMed

    Svatek, Simon A; Scott, Oliver R; Rivett, Jasmine P H; Wright, Katherine; Baldoni, Matteo; Bichoutskaia, Elena; Taniguchi, Takashi; Watanabe, Kenji; Marsden, Alexander J; Wilson, Neil R; Beton, Peter H

    2015-01-14

    The adsorption of the alkane tetratetracontane (TTC, C44H90) on graphene induces the formation of a curved surface stabilized by a gain in adsorption energy. This effect arises from a curvature-dependent variation of a moiré pattern due to the mismatch of the carbon-carbon separation in the adsorbed molecule and the period of graphene. The effect is observed when graphene is transferred onto a deformable substrate, which in our case is the interface between water layers adsorbed on mica and an organic solvent, but is not observed on more rigid substrates such as boron nitride. Our results show that molecular adsorption can be influenced by substrate curvature, provide an example of two-dimensional molecular self-assembly on a soft, responsive interface, and demonstrate that the mechanical properties of graphene may be modified by molecular adsorption, which is of relevance to nanomechanical systems, electronics, and membrane technology. PMID:25469625

  3. Nanorheology of adsorbed polymer chains immersed in pure solvent.

    PubMed

    Lapique, Fabrice; Montfort, Jean Pierre; Derail, Christophe

    2015-06-01

    Long linear chains of polybutadiene are adsorbed on the two surfaces of a surface force apparatus and immersed in pure tetradecane. The hydrodynamic force was measured by drainage experiments and by frequency sweeps at constant distances. We related the hydrodynamic thickness to the chain dimension. The complex modulus encompasses the shear modulus and, at distances lower than the hydrodynamic thickness, a compression modulus. The compression term was related to the static force which appears when the two adsorbed layers are overlapped. The complex shear modulus was interpreted by a two-components hydrodynamic model proposed by P. Sens et al. We first complemented the theoretical model. Then, our experimental data fit the proposed viscoelastic expressions in the entire range of distances. The storage modulus is supposed to be affected by a residue of free chains and by the dispersion of the loop lengths. PMID:26087919

  4. Adsorbate-Induced Curvature and Stiffening of Graphene

    PubMed Central

    2014-01-01

    The adsorption of the alkane tetratetracontane (TTC, C44H90) on graphene induces the formation of a curved surface stabilized by a gain in adsorption energy. This effect arises from a curvature-dependent variation of a moiré pattern due to the mismatch of the carbon–carbon separation in the adsorbed molecule and the period of graphene. The effect is observed when graphene is transferred onto a deformable substrate, which in our case is the interface between water layers adsorbed on mica and an organic solvent, but is not observed on more rigid substrates such as boron nitride. Our results show that molecular adsorption can be influenced by substrate curvature, provide an example of two-dimensional molecular self-assembly on a soft, responsive interface, and demonstrate that the mechanical properties of graphene may be modified by molecular adsorption, which is of relevance to nanomechanical systems, electronics, and membrane technology. PMID:25469625

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

    PubMed

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

    2014-11-01

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

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

    SciTech Connect

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

    2005-12-01

    Performance and produced polymer evaluation of four alkaline-surfactant-polymer projects concluded that only one of the projects could have benefited from combining the alkaline-surfactant-polymer and gelation technologies. Cambridge, the 1993 Daqing, Mellott Ranch, and the Wardlaw alkaline-surfacant-polymer floods were studied. An initial gel treatment followed by an alkaline-surfactant-polymer flood in the Wardlaw field would have been a benefit due to reduction of fracture flow. Numerical simulation demonstrated that reducing the permeability of a high permeability zone of a reservoir with gel improved both waterflood and alkaline-surfactant-polymer flood oil recovery. A Minnelusa reservoir with both A and B sand production was simulated. A and B sands are separated by a shale layer. A sand and B sand waterflood oil recovery was improved by 196,000 bbls or 3.3% OOIP when a gel was placed in the B sand. Alkaline-surfactant-polymer flood oil recovery improvement over a waterflood was 392,000 bbls or 6.5% OOIP. Placing a gel into the B sand prior to an alkaline-surfactant-polymer flood resulted in 989,000 bbl or 16.4% OOIP more oil than only water injection. A sand and B sand alkaline-surfactant-polymer flood oil recovery was improved by 596,000 bbls or 9.9% OOIP when a gel was placed in the B sand.

  7. Quasiparticle excitations of adsorbates on doped graphene

    NASA Astrophysics Data System (ADS)

    Lischner, Johannes; Wickenburg, Sebastian; Wong, Dillon; Karrasch, Christoph; Wang, Yang; Lu, Jiong; Omrani, Arash A.; Brar, Victor; Tsai, Hsin-Zon; Wu, Qiong; Corsetti, Fabiano; Mostofi, Arash; Kawakami, Roland K.; Moore, Joel; Zettl, Alex; Louie, Steven G.; Crommie, Mike

    Adsorbed atoms and molecules can modify the electronic structure of graphene, but in turn it is also possible to control the properties of adsorbates via the graphene substrate. In my talk, I will discuss the electronic structure of F4-TCNQ molecules on doped graphene and present a first-principles based theory of quasiparticle excitations that captures the interplay of doping-dependent image charge interactions between substrate and adsorbate and electron-electron interaction effects on the molecule. The resulting doping-dependent quasiparticle energies will be compared to experimental scanning tunnelling spectra. Finally, I will also discuss the effects of charged adsorbates on the electronic structure of doped graphene.

  8. Bowl inversion of surface-adsorbed sumanene.

    PubMed

    Jaafar, Rached; Pignedoli, Carlo A; Bussi, Giovanni; Aït-Mansour, Kamel; Groening, Oliver; Amaya, Toru; Hirao, Toshikazu; Fasel, Roman; Ruffieux, Pascal

    2014-10-01

    Bowl-shaped π-conjugated compounds offer the possibility to study curvature-dependent host-guest interactions and chemical reactivity in ideal model systems. For surface-adsorbed π bowls, however, only conformations with the bowl opening pointing away from the surface have been observed so far. Here we show for sumanene on Ag(111) that both bowl-up and bowl-down conformations can be stabilized. Analysis of the molecular layer as a function of coverage reveals an unprecedented structural phase transition involving a bowl inversion of one-third of the molecules. On the basis of scanning tunneling microscopy (STM) and complementary atomistic simulations, we develop a model that describes the observed phase transition in terms of a subtle interplay between inversion-dependent adsorption energies and intermolecular interactions. In addition, we explore the coexisting bowl-up and -down conformations with respect to host-guest binding of methane. STM reveals a clear energetic preference for methane binding to the concave face of sumanene. PMID:25181621

  9. Mechanisms of Polyelectrolyte Enhanced Surfactant Adsorption at the Air-Water Interface

    PubMed Central

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

    2009-01-01

    Chitosan, a naturally occurring cationic polyelectrolyte, restores the adsorption of the clinical lung surfactant Survanta to the air-water interface in the presence of albumin at much lower concentrations than uncharged polymers such as polyethylene glycol. This is consistent with the positively charged chitosan forming ion pairs with negative charges on the albumin and lung surfactant particles, reducing the net charge in the double-layer, and decreasing the electrostatic energy barrier to adsorption to the air-water interface. However, chitosan, like other polyelectrolytes, cannot perfectly match the charge distribution on the surfactant, which leads to patches of positive and negative charge at net neutrality. Increasing the chitosan concentration further leads to a reduction in the rate of surfactant adsorption consistent with an over-compensation of the negative charge on the surfactant and albumin surfaces, which creates a new repulsive electrostatic potential between the now cationic surfaces. This charge neutralization followed by charge inversion explains the window of polyelectrolyte concentration that enhances surfactant adsorption; the same physical mechanism is observed in flocculation and re-stabilization of anionic colloids by chitosan and in alternate layer deposition of anionic and cationic polyelectrolytes on charged colloids. PMID:19366599

  10. Anomalous thickness variation of the foam films stabilized by weak non-ionic surfactants.

    PubMed

    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.

  11. Aerosol delivery of synthetic lung surfactant

    PubMed Central

    Hernández-Juviel, José M.; Waring, Alan J.

    2014-01-01

    Background. Nasal continuous positive airway pressure (nCPAP) is a widely accepted technique of non-invasive respiratory support in premature infants with respiratory distress syndrome due to lack of lung surfactant. If this approach fails, the next step is often intubation, mechanical ventilation (MV) and intratracheal instillation of clinical lung surfactant. Objective. To investigate whether aerosol delivery of advanced synthetic lung surfactant, consisting of peptide mimics of surfactant proteins B and C (SP-B and SP-C) and synthetic lipids, during nCPAP improves lung function in surfactant-deficient rabbits. Methods. Experimental synthetic lung surfactants were produced by formulating 3% Super Mini-B peptide (SMB surfactant), a highly surface active SP-B mimic, and a combination of 1.5% SMB and 1.5% of the SP-C mimic SP-Css ion-lock 1 (BC surfactant), with a synthetic lipid mixture. After testing aerosol generation using a vibrating membrane nebulizer and aerosol conditioning (particle size, surfactant composition and surface activity), we investigated the effects of aerosol delivery of synthetic SMB and BC surfactant preparations on oxygenation and lung compliance in saline-lavaged, surfactant-deficient rabbits, supported with either nCPAP or MV. Results. Particle size distribution of the surfactant aerosols was within the 1–3 µm distribution range and surfactant activity was not affected by aerosolization. At a dose equivalent to clinical surfactant therapy in premature infants (100 mg/kg), aerosol delivery of both synthetic surfactant preparations led to a quick and clinically relevant improvement in oxygenation and lung compliance in the rabbits. Lung function recovered to a greater extent in rabbits supported with MV than with nCPAP. BC surfactant outperformed SMB surfactant in improving lung function and was associated with higher phospholipid values in bronchoalveolar lavage fluid; these findings were irrespective of the type of ventilatory support

  12. Surfactant flooding oil recovery process

    SciTech Connect

    Carlin, J.; Mills, M.; Tyler, T.; Ware, J.

    1980-07-29

    A method of recovering petroleum from a subterranean petroleum-containing formation penrated by at least one injection well and by at least one spaced apart production well is described. The wells being in fluid communication with the formation, comprising: (A) injecting into the formation via the injection well an aqueous, saline fluid having a salinity greater than 20,000 ppM total dissolved solids and containing a surfactant comprising petroleum sulfonates whose average equivalent weight is from 350 to 400, from 15 to 35 percent of said pertroleum sulfonates having equilvent weights of 350 or less, from 30 to 50 percent of said petroleum sulfonates having equivalent weights greater than 350 and less than 500, and from 10 to 40 percent of said petroleum sulfonates having equivalent weights of 500 and above and a solubilizing co-surfactant selected from the group consisting of ethoxylated alkanols, ethoxylated alkylphenols, alkyl or alkylaryl polyethoxy sulfates, alkyl or alkylaryl polyalkoxyalkyl sulfonates, and mixtures thereof, said surfactant fluid displacing petroleum toward the production well; and (B) recovering petroleum displaced by the surfactant fluids from the formation and via the production well.

  13. Cationic surfactants based on ferrocene

    SciTech Connect

    Pankratov, V.A.; Kucherova, N.L.; Abramzon, A.A.

    1988-07-20

    Quaternary ammonium salts based on ferrocene were synthesized and their surface active properties were studied as potential cationic surfactants and for uses including antiknock compounds. The salts were halide and nitrate derivatives of dimethylferrocenylmethylammonium and were prepared by aminomethylation of ferrocene. Chemical reaction yields, melting points, surface tension isotherms, and other characteristics were assessed.

  14. The uranium from seawater program at PNNL: Overview of marine testing, adsorbent characterization, adsorbent durability, adsorbent toxicity, and deployment studies

    DOE PAGES

    Gill, Gary A.; Kuo, Li -Jung; Janke, Christopher James; Park, Jiyeon; Jeters, Robert T.; Bonheyo, George T.; Pan, Horng -Bin; Wai, Chien; Khangaonkar, Tarang P.; Bianucci, Laura; et al

    2016-02-07

    The Pacific Northwest National Laboratory's (PNNL) Marine Science Laboratory (MSL) located along the coast of Washington State is evaluating the performance of uranium adsorption materials being developed for seawater extraction under realistic marine conditions with natural seawater. Two types of exposure systems were employed in this program: flow-through columns for testing of fixed beds of individual fibers and pellets and a recirculating water flume for testing of braided adsorbent material. Testing consists of measurements of the adsorption of uranium and other elements from seawater as a function of time, typically 42 to 56 day exposures, to determine the adsorbent capacitymore » and adsorption rate (kinetics). Analysis of uranium and other trace elements collected by the adsorbents was conducted following strong acid digestion of the adsorbent with 50% aqua regia using either Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The ORNL 38H adsorbent had a 56 day adsorption capacity of 3.30 ± 0.68 g U/ kg adsorbent (normalized to a salinity of 35 psu), a saturation adsorption capacity of 4.89 ± 0.83 g U/kg of adsorbent material (normalized to a salinity of 35 psu) and a half-saturation time of 28 10 days. The AF1 adsorbent material had a 56 day adsorption capacity of 3.9 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu), a saturation capacity of 5.4 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu) and a half saturation time of 23 2 days. The ORNL amidoxime-based adsorbent materials are not specific for uranium, but also adsorb other elements from seawater. The major doubly charged cations in seawater (Ca and Mg) account for a majority of the cations adsorbed (61% by mass and 74% by molar percent). For the ORNL AF1 adsorbent material, U is the 4th most abundant element adsorbed by mass and 7th most abundant by molar percentage. Marine testing

  15. Binary coalescence of gas bubbles in the presence of a non-ionic surfactant.

    PubMed

    Duerr-Auster, N; Gunde, R; Mäder, R; Windhab, Erich J

    2009-05-15

    The coalescence behavior of air bubbles in a dilute aqueous surfactant solution of a polyglycerol fatty acid ester (PGE), a commercial non-ionic surfactant, is investigated in a binary coalescence experiment. The focus is on the influence of the ionic strength of the solution on the rate of coalescence. Results are compared with the adsorption kinetics and surface shear/dilatational rheological properties of the surfactant. Experiments show that the coalescence frequency is significantly lower at low ionic strength, and that bubble stability increases with increasing aging time. Stabilization occurs via surfactant adsorption and a resulting electrostatic and/or steric repulsive force. The electrostatic force presumably originates from small amounts of anionic fatty acid soaps, which are residues from the industrial synthesis. The steric force can be related to the adsorption of visco-elastic layers of PGE at the air-water interface. PMID:19200557

  16. Turning bubbles on and off during boiling using charged surfactants

    PubMed Central

    Cho, H. Jeremy; Mizerak, Jordan P.; Wang, Evelyn N.

    2015-01-01

    Boiling—a process that has powered industries since the steam age—is governed by bubble formation. State-of-the-art boiling surfaces often increase bubble nucleation via roughness and/or wettability modification to increase performance. However, without active in situ control of bubbles, temperature or steam generation cannot be adjusted for a given heat input. Here we report the ability to turn bubbles ‘on and off' independent of heat input during boiling both temporally and spatially via molecular manipulation of the boiling surface. As a result, we can rapidly and reversibly alter heat transfer performance up to an order of magnitude. Our experiments show that this active control is achieved by electrostatically adsorbing and desorbing charged surfactants to alter the wettability of the surface, thereby affecting nucleation. This approach can improve performance and flexibility in existing boiling technologies as well as enable emerging or unprecedented energy applications. PMID:26486275

  17. Turning bubbles on and off during boiling using charged surfactants.

    PubMed

    Cho, H Jeremy; Mizerak, Jordan P; Wang, Evelyn N

    2015-10-21

    Boiling--a process that has powered industries since the steam age--is governed by bubble formation. State-of-the-art boiling surfaces often increase bubble nucleation via roughness and/or wettability modification to increase performance. However, without active in situ control of bubbles, temperature or steam generation cannot be adjusted for a given heat input. Here we report the ability to turn bubbles 'on and off' independent of heat input during boiling both temporally and spatially via molecular manipulation of the boiling surface. As a result, we can rapidly and reversibly alter heat transfer performance up to an order of magnitude. Our experiments show that this active control is achieved by electrostatically adsorbing and desorbing charged surfactants to alter the wettability of the surface, thereby affecting nucleation. This approach can improve performance and flexibility in existing boiling technologies as well as enable emerging or unprecedented energy applications.

  18. Interaction of cationic surfactants with iron and sodium montmorillonite suspensions

    SciTech Connect

    Chen, G.; Han, B.; Yan, H.

    1998-05-15

    Calorimetry, static technique, and X-ray diffraction (XRD) analysis were employed to study the adsorption of cetyltrimethylammonium bromide (CTAB) and dodecyltrimethylammonium bromide (DTAB) on Fe-montmorillonite and Na-montmorillonite suspensions. The results show that the process of adsorption is exothermic and that the type of clay and the alkyl chain length of surfactant affect the amount of adsorption and the enthalpy of adsorption significantly but that the effect of temperature is very limited in the temperature range studied. The magnitudes of adsorption amount and adsorption enthalpy follow the order Na-montmorillonite > Fe-montmorillonite, CTAB > DTAB. The basal spacings determined by X-ray powder diffraction indicate that the CTAB adsorbed between the clay interlayers in a bilayer arrangement, while the DTAB formed bilayers or monolayers at saturation adsorption between the Na-montmorillonite and Fe-montmorillonite interlayers, respectively. The adsorption mechanism is also discussed on the basis of the experimental data.

  19. New Lyotropic Liquid Crystals Based on Surfactants

    NASA Astrophysics Data System (ADS)

    Honciuc, Maria; Borlescu, C.; Popa, Carmen

    We presented here the phase diagrams and the influence of the external electric field on the lyotropic liquid crystal phase (LLC) for some binary and pseudoternary systems based on surfactants. Binary systems are of the type surfactant/water (S/W) and the pseudoternary systems are of the type surfactant/oil/water (S/O/W). Two surfactants have been used: the lauryl alcohol ethoxilated with 11 molecules of ethylene oxide (LA11EO), which is a nonionic compound, and a mixture of LA11EO with the cationic surfactant named alkyl C12-C14-dimethyl-benzyl ammonium chloride. Based on these two types of surfactants, pseudoternary systems were prepared. Pine oil has been used as the oil. The region where the LLC phase appears depends on the concentration of the surfactant and that of the pine oil, respectively. It is strongly influenced by the nature of the surfactant and by the presence of the pine oil for the same type of surfactant. The influence of the external electric field, investigated by measuring the electric current appearing in the samples for different concentrations of surfactant and pine oil was found to be more important in the case of the systems based on the nonionic-cationic mixture of surfactants. The results are discussed in terms of a theoretical model based on the local thermal equilibrium approach for systems running nonstatic processes.

  20. Double tapered surfactant waterflood oil recovery process

    SciTech Connect

    Carlin, J.T.; Tyler, T.N.

    1980-11-11

    Disclosed is an oil recovery process for recovering oil from subterranean formations containing relatively high salinity water , said process employing an aqueous surfactant fluid containing at least two surfactants, one primary anionic surfactant such as petroleum sulfonate and a solubilizing cosurfactant such as an alkyl or alkylaryl, polyethoxy sulfate or sulfonate. The process comprises injecting a plurality of slugs of surfactant fluids followed by a low salinity fluid containing a viscosifying amount of a hydrophilic polymer. The salinity and concentration of solubilizing cosurfactant of each surfactant slug are both decreased from the maximum level in the first slug of the surfactant fluid and in successive slugs to a minimum level at the last slug of the surfactant fluid.

  1. Microstructure of Mixed Surfactant Solutions by Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Naranjo, Edward

    1995-01-01

    biological surfactants. We have found that subtle changes by surfactant additives to phosphatidylcholines (PC) produce dramatic changes in the microstructure of the composite that are impossible to determine from simple scattering experiments. Novel microstructures were observed at mole ratios from 4/1 to 9/1 long chain (Di-C_{16}PC)/short chain lipid (Di-C_7PC), including disc-like micelles and rippled bilayers at room temperature. We have also observed for the first time the formation of single layered ripple phase bilayer fragments. The formation of such fragments eliminates a number of theories of formation of this unique structure that depend on coupling between bilayers. In a similar system, dimyristoyl phosphatidylcholine (DMPC) mixed with the branched alcohol geraniol produces a bluish and extremely viscoelastic phase of giant multilamellar wormy vesicles. This phase shows the Weissenberg effect under flow due to the distortion of the entangled vesicles and may be related to fluid lamellar phases and L _3 phases often seen in surfactant-alcohol -water systems. Lysophosphatidylcholine, the single-chain counterpart of the diacyl phospholipids, can also form bilayer phases when combined with long-chain fatty acids in water. The phase transition characteristics and appearance of the bilayers in equimolar mixtures of lysolipid and fatty acid are similar to those of the diacyl-PC. Electron microscopy reveals large extended multilayers in mixtures with excess lysolipid and multilamellar vesicles in mixtures with excess fatty acid.

  2. Complete braided adsorbent for marine testing to demonstrate 3g-U/kg-adsorbent

    SciTech Connect

    Janke, Chris; Yatsandra, Oyola; Mayes, Richard; none,; Gill, Gary; Li-Jung, Kuo; Wood, Jordana; Sadananda, Das

    2014-04-30

    ORNL has manufactured four braided adsorbents that successfully demonstrated uranium adsorption capacities ranging from 3.0-3.6 g-U/kg-adsorbent in marine testing at PNNL. Four new braided and leno woven fabric adsorbents have also been prepared by ORNL and are currently undergoing marine testing at PNNL.

  3. Cross-flow ultrafiltration of micellar surfactant solutions

    SciTech Connect

    Markels, J.H.; Lynn, S.; Radke, C.J.

    1995-09-01

    A steady-state fouling-resistance and osmotic-pressure model is used to predict flux in the laminar, cross-flow ultrafiltration of micellar cetyl (=hexadecyl)pyridinium chloride (CPC) solutions at 0.01-M NaCl background electrolyte. The model assumes a constant overall hydraulic resistance including the effect of surfactant fouling and native membrane resistance. Measurements of osmotic pressures of CPC solutions at 0.01-M NaCl as a function of surfactant concentration describe the effect of concentration polarization on permeate flux. Two types of asymmetric polyethersulfone membranes are used: 5,000 molecular weight cutoff (MWCO) membranes that allow partial monomer permeation, but quantitatively reject all micelles; 50,000 MWCO membranes that allow some micelle permeation. For the former, the intrinsic rejection coefficient for monomer, measured separately, is sufficient to describe surfactant rejection, without adjustable parameters. Predictions of the volumetric flux of the permeate, including the value of the limiting flux, agree well with the experimental results over the entire range of pressure drop, axial velocity, and bulk surfactant concentration. For the 50,000 MWCO membranes the data are described using a best-fit value of the overall surfactant rejection coefficient. For the first time, unusual behavior is observed experimentally in which the flux levels off with increasing pressure drop across the membrane, only to increase sharply again at higher applied pressure drop. Both effects are in accord with the proposed model. No gel layer need be postulated to explain the flux behavior of either membrane type.

  4. Prospects for simulating macromolecular surfactant chemistry at the ocean-atmosphere boundary

    NASA Astrophysics Data System (ADS)

    Elliott, S.; Burrows, S. M.; Deal, C.; Liu, X.; Long, M.; Ogunro, O.; Russell, L. M.; Wingenter, O.

    2014-05-01

    Biogenic lipids and polymers are surveyed for their ability to adsorb at the water-air interfaces associated with bubbles, marine microlayers and particles in the overlying boundary layer. Representative ocean biogeochemical regimes are defined in order to estimate local concentrations for the major macromolecular classes. Surfactant equilibria and maximum excess are then derived based on a network of model compounds. Relative local coverage and upward mass transport follow directly, and specific chemical structures can be placed into regional rank order. Lipids and denatured protein-like polymers dominate at the selected locations. The assigned monolayer phase states are variable, whether assessed along bubbles or at the atmospheric spray droplet perimeter. Since oceanic film compositions prove to be irregular, effects on gas and organic transfer are expected to exhibit geographic dependence as well. Moreover, the core arguments extend across the sea-air interface into aerosol-cloud systems. Fundamental nascent chemical properties including mass to carbon ratio and density depend strongly on the geochemical state of source waters. High surface pressures may suppress the Kelvin effect, and marine organic hygroscopicities are almost entirely unconstrained. While bubble adsorption provides a well-known means for transporting lipidic or proteinaceous material into sea spray, the same cannot be said of polysaccharides. Carbohydrates tend to be strongly hydrophilic so that their excess carbon mass is low despite stacked polymeric geometries. Since sugars are abundant in the marine aerosol, gel-based mechanisms may be required to achieve uplift. Uncertainties distill to a global scale dearth of information regarding two dimensional kinetics and equilibria. Nonetheless simulations are recommended, to initiate the process of systems level quantification.

  5. The effects of surfactants on the permeability of isolated perfused fish gills to urea.

    PubMed

    Partearroyo, M A; Pilling, S J; Jones, M N

    1992-04-01

    1. The diffusional transfer capacity of [14C]urea in isolated perfused trout (Oncorhynchus mykiss) gills in the presence of sodium n-dodecylsulphate (SDS), n-dodecyltrimethylammonium bromide (DTAB) and p-t-octylbenzene oxyethylene10 (Triton X-100) has been measured over a range of surfactant concentrations. 2. Urea has been shown to be transported transcellularly through the respiratory cells of the gill secondary lamellae by passive diffusion. Each surfactant was found to markedly increase the rate of diffusion and the diffusional transfer capacity reached a steady-state at a particular surfactant concentration. 3. The steady state flux was increased by surfactant in the sequence DTAB greater than SDS greater than Triton X-100 and the surfactant concentrations in terms of the critical micelle concentration (CMC) at which the diffusional transfer capacities reached limiting values were 0.92 x CMC (SDS), 0.53 x CMC (DTAB) and 2.5 x CMC (Triton X-100). 4. Compared to interactions between isolated epithelial cells and the surfactants, the rates at which the surfactants changed the urea flux were slow, suggesting that the mucus layer plays a significant role in protecting the epithelial cells of the secondary lamellae from disruption. 5. Relative to the other surfactants, DTAB had the most marked effect on both the rate of flux change and on the magnitude of the change, at concentrations which are low relative to the CMC, suggesting a more specific interaction with the negatively charged mucus layer consistent with the toxic effects of quaternary ammonium compounds on aquatic organisms.

  6. Fluorescence Response of Conjugated Polyelectrolyte in an Immiscible Two-Phase System via Nonelectrostatic Interaction with Surfactants.

    PubMed

    Kim, Beomsu Shin-Il; Jin, Young-Jae; Sakaguchi, Toshikazu; Lee, Wang-Eun; Kwak, Giseop

    2015-06-24

    This paper reports a unique fluorescence (FL) response and diverse applications of conjugated polyelectrolyte (CPE) through nonelectrostatic interaction with appropriate (bio)surfactants in an immiscible two-phase system. A sulfonated microporous conjugated polymer (SMCP) with a conformation-variable intramolecular stacked structure was used as the CPE film. Despite the extremely high hydrophilicity, the SMCP film responded significantly to the hydrophobic circumstances, either physicochemically or electronically, in the presence of water-in-oil (w/o)-type nonionic surfactants with appropriate hydrophile-lipophile balance (HLB) values. The polymer film became fully wet with hydrophobic solvents due to the addition of small amounts of (bio)surfactant to reveal remarkable FL emission enhancement and chromism. Microcontact and inkjet printing using the SMCP film (or SMCP-adsorbed paper) and the surfactant solution as substrate and ink, respectively, provided high-resolution FL images due to the distinctive surfactant-induced FL change (SIFC) characteristic. Moreover, the additional electrostatic interaction of SMCP film with oppositely charged surfactants further enhanced the FL emission. Our findings will help comprehensive understanding of the nonelectrostatic SIFC mechanism of CPEs and development of novel SIFC-active materials.

  7. Adsorbate modification of the structural, electronic, and magnetic properties of ferromagnetic fcc {110} surfaces

    NASA Astrophysics Data System (ADS)

    Gunn, D. S. D.; Jenkins, Stephen J.

    2011-03-01

    We identify trends in structural, electronic, and magnetic modifications that occur on ferromagnetic {110} surfaces upon varying either the substrate material or the adsorbate species. First, we have modeled the adsorption of several first-row p-block elements on the surface of fcc Co{110} at two coverages [0.5 and 1.0 monolayer (ML)]. All adsorbates were found to expand the distance between the first and second substrate layers and to contract the distance between the second and third layers. The energetic location of a characteristic trough in the density-of-d-states difference plot correlates with the direction of the adsorbate magnetic coupling to the surface, and a trend of antiferromagnetic to ferromagnetic coupling to the surface was observed across the elements from boron to fluorine. A high fluorine adatom coverage (1.0 ML) was found to enhance the surface spin magnetic moment by 11%. Second, we also calculate and contrast adsorption of 0.5 and 1.0 ML of carbon, nitrogen, and oxygen adatoms on fcc iron, cobalt, and nickel {110} surfaces and compare the structural, electronic, and magnetic properties of these systems. Carbon and nitrogen are found to couple antiferromagnetically, and oxygen ferromagnetically, to all surfaces. It was found that antiferromagnetically coupled adsorbates retained their largest spin moment values on iron, whereas ferromagnetically coupled adsorbates possessed their lowest moments on this surface. The strongly localized influence of these adsorbates is clearly illustrated in partial density-of-states plots for the surface atoms.

  8. Retention of radium from thermal waters on sand filters and adsorbents.

    PubMed

    Elejalde, C; Herranz, M; Idoeta, R; Legarda, F; Romero, F; Baeza, A

    2007-06-18

    This study was focussed on laboratory experiences of retention of radium from one thermal water on sand filters and adsorbents, trying to find an easy method for the elimination in drinkable waters polluted with this natural radio-nuclide. A thermal water from Cantabria (Spain) was selected for this work. Retention experiences were made with columns of 35 mm of diameter containing 15 cm layers of washed river sand or 4 cm layers of zeolite A3, passing known volumes of thermal water at flows between 4 and 40 ml/min with control of the retained radium by determining the amount in the water after the treatment. The statistical analysis of data suggests that retention depends on the flow and the volume passed through the columns. As additional adsorbents were used kaolin and a clay rich in illite. Jar-test experiences were made agitating known weights of adsorbents with the selected thermal water, with addition of flocculants and determination of radium in filtrated water after the treatment. Data suggest that retention is related to the weight of adsorbent used, but important quantities of radium seem remain in solution for higher amounts of adsorbents, according to the statistical treatment of data. The elution of retained radium from columns or adsorbents, previously used in experiences, should be the aim of a future research.

  9. Surfactant-mediated growth of Ge/Si(0 0 1) studied by Raman spectroscopy and TEM

    NASA Astrophysics Data System (ADS)

    Brill, G.; Smith, David J.; Chandrasekhar, D.; Gogotsi, Y.; Prociuk, A.; Sivananthan, S.

    1999-05-01

    Growth of Ge/Si follows the Stranski-Krastanov growth mode (2D→3D) because of the 4.2% lattice mismatch between Ge and Si. However, the growth mode can be altered to Frank-Van der Merwe (layer-by-layer) by depositing a suitable surfactant. In this study, we have grown thin and thick Ge(0 0 1)/Si(0 0 1) MBE layers with and without As deposition prior to Ge growth in order to investigate the details of surfactant-mediated epitaxy. Raman spectroscopy shows that without As surfactant use, Ge and Si interdiffuse at the interface and form an alloy. Furthermore, peak shift measurements as well as cross-sectional electron micrographs reveal that layers grown with As slowly relieve misfit strain through the accommodation of Lomer edge dislocations at the interface leaving a relaxed, nearly defect-free layer.

  10. Water Dispersible, Positively and Negatively Charged MoS2 Nanosheets: Surface Chemistry and the Role of Surfactant Binding.

    PubMed

    Gupta, Amit; Arunachalam, Vaishali; Vasudevan, Sukumaran

    2015-02-19

    Stable aqueous dispersions of atomically thin layered MoS2 nanosheets have been obtained by sonication in the presence of ionic surfactants. The dispersions are stabilized by electrostatic repulsion between the sheets, and we show that the sign of the charge on the MoS2 nanosheets, either positive or negative, can be can be controlled by the choice of the surfactant. Using techniques from solution NMR, we show that the surfactant chains are weakly bound to the MoS2 sheets and undergo rapid exchange with free surfactant chains present in the dispersion. In situ nuclear Overhauser effect spectroscopic measurements provide direct evidence that the surfactant chains lie flat, arranged randomly on the basal plane of the MoS2 nanosheets with their charged headgroup exposed. These results provide a chemical perspective for understanding the stability of these inorganic nanosheets in aqueous dispersions and the origin of the charge on the sheets.

  11. Database of Novel and Emerging Adsorbent Materials

    National Institute of Standards and Technology Data Gateway

    SRD 205 NIST/ARPA-E Database of Novel and Emerging Adsorbent Materials (Web, free access)   The NIST/ARPA-E Database of Novel and Emerging Adsorbent Materials is a free, web-based catalog of adsorbent materials and measured adsorption properties of numerous materials obtained from article entries from the scientific literature. Search fields for the database include adsorbent material, adsorbate gas, experimental conditions (pressure, temperature), and bibliographic information (author, title, journal), and results from queries are provided as a list of articles matching the search parameters. The database also contains adsorption isotherms digitized from the cataloged articles, which can be compared visually online in the web application or exported for offline analysis.

  12. NOx adsorber and method of regenerating same

    DOEpatents

    Endicott, Dennis L.; Verkiel, Maarten; Driscoll, James J.

    2007-01-30

    New technologies, such as NOx adsorber catalytic converters, are being used to meet increasingly stringent regulations on undesirable emissions, including NOx emissions. NOx adsorbers must be periodically regenerated, which requires an increased fuel consumption. The present disclosure includes a method of regenerating a NOx adsorber within a NOx adsorber catalytic converter. At least one sensor positioned downstream from the NOx adsorber senses, in the downstream exhaust, at least one of NOx, nitrous oxide and ammonia concentrations a plurality of times during a regeneration phase. The sensor is in communication with an electronic control module that includes a regeneration monitoring algorithm operable to end the regeneration phase when a time rate of change of the at least one of NOx, nitrous oxide and ammonia concentrations is after an expected plateau region begins.

  13. Fluorescence dynamics of microsphere-adsorbed sunscreens

    NASA Astrophysics Data System (ADS)

    Krishnan, R.

    2005-03-01

    Sunscreens are generally oily substances which are prepared in organic solvents, emulsions or dispersions with micro- or nanoparticles. These molecules adsorb to and integrate into skin cells. In order to understand the photophysical properties of the sunscreen, we compare steady-state and time-resolved fluorescence in organic solvent of varying dielectric constant ɛ and adsorbed to polystyrene microspheres and dispersed in water. Steady-state fluorescence is highest and average fluorescence lifetime longest in toluene, the solvent of lowest ɛ. However, there is no uniform dependence on ɛ. Sunscreens PABA and padimate-O show complex emission spectra. Microsphere-adsorbed sunscreens exhibit highly non-exponential decay, illustrative of multiple environments of the adsorbed molecule. The heterogeneous fluorescence dynamics likely characterizes sunscreen adsorbed to cells.

  14. Surfactant Facilitated Spreading of Aqueous Drops on Hydrophobic Surfaces

    NASA Technical Reports Server (NTRS)

    Kumar, Nitin; Couzis, Alex; Maldareili, Charles; Singh, Bhim (Technical Monitor)

    2001-01-01

    Microgravity technologies often require aqueous phases to spread over nonwetting hydrophobic solid surfaces. Surfactants facilitate the wetting of water on hydrophobic surfaces by adsorbing on the water/air and hydrophobic solid/water interfaces and lowering the surface tensions of these interfaces. The tension reductions decrease the contact angle, which increases the equilibrium wetted area. Hydrocarbon surfactants; (i.e., amphiphiles with a hydrophobic moiety consisting of an extended chain of (aliphatic) methylene -CH2- groups attached to a large polar group to give aqueous solubility) are capable of reducing the contact angles on surfaces which are not very hydrophobic, but do not reduce significantly the contact angles of the very hydrophobic surfaces such as parafilm, polyethylene or self assembled monolayers. Trisiloxane surfactants (amphiphiles with a hydrophobe consisting of methyl groups linked to a trisiloxane backbone in the form of a disk ((CH3)3-Si-O-Si-O-Si(CH3)3) and an extended ethoxylate (-(OCH2CH2)a-) polar group in the form of a chain with four or eight units) can significantly reduce the contact angle of water on a very hydrophobic surface and cause rapid and complete (or nearly complete) spreading (termed superspreading). The overall goal of the research described in this proposal is to establish and verify a theory for how trisiloxanes cause superspreading, and then use this knowledge as a guide to developing more general hydrocarbon based surfactant systems which superspread. We propose that the trisiloxane surfactants superspread because their structure allows them to strongly lower the high hydrophobic solid/aqueous tension when they adsorb to the solid surface. When the siloxane adsorbs, the hydrophobic disk parts of the molecule adsorb onto the surface removing the surface water. Since the cross-sectional area of the disk is larger than that of the extended ethoxylate chain, the disks can form a space-filling mat on the surface which

  15. Drops in Space: Super Oscillations and Surfactant Studies

    NASA Technical Reports Server (NTRS)

    Apfel, Robert E.; Tian, Yuren; Jankovsky, Joseph; Shi, Tao; Chen, X.; Holt, R. Glynn; Trinh, Eugene; Croonquist, Arvid; Thornton, Kathyrn C.; Sacco, Albert, Jr.; Coleman, Catherine; Leslie, Fred W.; Matthiesen, David H.

    1996-01-01

    An unprecedented microgravity observation of maximal shape oscillations of a surfactant-bearing water drop the size of a ping pong ball was observed during a mission of Space Shuttle Columbia as part of the second United States Microgravity Laboratory-USML-2 (STS-73, October 20-November 5, 1995). The observation was precipitated by the action of an intense sound field which produced a deforming force on the drop. When this deforming force was suddenly reduced, the drop executed nearly free and axisymmetric oscillations for several cycles, demonstrating a remarkable amplitude of nonlinear motion. Whether arising from the discussion of modes of oscillation of the atomic nucleus, or the explosion of stars, or how rain forms, the complex processes influencing the motion, fission, and coalescence of drops have fascinated scientists for centuries. Therefore, the axisymmetric oscillations of a maximally deformed liquid drop are noteworthy, not only for their scientific value but also for their aesthetic character. Scientists from Yale University, the Jet Propulsion Laboratory (JPL) and Vanderbilt University conducted liquid drop experiments in microgravity using the acoustic positioning/manipulation environment of the Drop Physics Module (DPM). The Yale/JPL group's objectives were to study the rheological properties of liquid drop surfaces on which are adsorbed surfactant molecules, and to infer surface properties such as surface tension, Gibb's elasticity, and surface dilatational viscosity by using a theory which relies on spherical symmetry to solve the momentum and mass transport equations.

  16. Scalable, printable, surfactant-free graphene ink directly from graphite.

    PubMed

    Han, X; Chen, Y; Zhu, H; Preston, C; Wan, J; Fang, Z; Hu, L

    2013-05-24

    In this manuscript, we develop printable graphene ink through a solvent-exchange method. Printable graphene ink in ethanol and water free of any surfactant is dependent on matching the surface tension of the cross-solvent with the graphene surface energy. Percolative transport behavior is observed for films made of this printable ink. Optical conductivity is then calculated based on sheet resistance, optical transmittance, and thickness. Upon analyzing the ratio of dc/optical conductivity versus flake size/layer number, we report that our dc/optical conductivity is among the highest of films based on direct deposited graphene ink. This is the first demonstration of scalable, printable, surfactant-free graphene ink derived directly from graphite. PMID:23609377

  17. Scalable, printable, surfactant-free graphene ink directly from graphite

    NASA Astrophysics Data System (ADS)

    Han, X.; Chen, Y.; Zhu, H.; Preston, C.; Wan, J.; Fang, Z.; Hu, L.

    2013-05-01

    In this manuscript, we develop printable graphene ink through a solvent-exchange method. Printable graphene ink in ethanol and water free of any surfactant is dependent on matching the surface tension of the cross-solvent with the graphene surface energy. Percolative transport behavior is observed for films made of this printable ink. Optical conductivity is then calculated based on sheet resistance, optical transmittance, and thickness. Upon analyzing the ratio of dc/optical conductivity versus flake size/layer number, we report that our dc/optical conductivity is among the highest of films based on direct deposited graphene ink. This is the first demonstration of scalable, printable, surfactant-free graphene ink derived directly from graphite.

  18. Surfactant-treated graphene covered polyaniline nanowires for supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Rajagopalan, Balasubramaniyan; Hur, Seung Hyun; Chung, Jin Suk

    2015-04-01

    Surfactant-treated graphene/polyaniline (G/PANI) nanocomposites were prepared by the MnO2 template-aided oxidative polymerization of aniline (ANI) on the surfactant-treated graphene sheets. The electrochemical performances of the G/PANI nanocomposites in a three-electrode system using an aqueous sulfuric acid as an electrolyte exhibited a specific capacitance of 436 F g-1 at 1 A g-1, which is much higher than the specific capacitance of pure PANI (367 F g-1). Such a higher specific capacitance of the G/PANI nanocomposite inferred an excellent synergistic effect of respective pseudocapacitance and electrical double-layer capacitance of PANI and graphene.

  19. Surfactant-Assisted Growth of CdS Thin Films for Photovoltaic Applications

    SciTech Connect

    Perkins, C. L.; Hasoon, F. S.

    2006-05-01

    A common nonionic surfactant, Triton X-100, was used to modify the chemical bath deposition of CdS 'buffer' layers on Cu(In,Ga)Se{sub 2} (CIGS) thin films. Addition of the surfactant to the CdS deposition bath allowed increased wetting of Cu(In,Ga)Se{sub 2} substrates and an increase in the uniformity of films, especially on model hydrophobic substrates. X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy data demonstrate that films produced with the surfactant have the same chemical and electronic properties as films grown without it. In CdS/Cu(In,Ga)Se{sub 2} devices, it was found that Triton X-100 allowed the use of CdS layers that were three to four times thinner than those used normally in high efficiency CIGS-based devices and eliminated the large drops in open-circuit voltage that usually accompany very thin buffer layers. For these thin CdS layers and relative to devices made without the surfactant, average absolute cell efficiencies were increased from 10.5% to 14.8% or by a relative 41%. Visual inspection of the CdS depositions reveals one possible mechanism of the surfactant's effects: Bubbles that form and adhere to the CIGS surface during the chemical bath deposition are almost completely eliminated with the addition of the TX-100. Thus, junction nonuniformities, pinholes, and thin areas in the CdS layer caused by poor wetting of the substrate surface are sharply reduced, leading to large increases in the open-circuit voltage in devices produced with the surfactant.

  20. Surfactants in the management of rhinopathologies

    PubMed Central

    Rosen, Philip L.; Palmer, James N.; O'Malley, Bert W.

    2013-01-01

    Background: Surfactants are a class of amphiphilic surface active compounds that show several unique physical properties at liquid–liquid or liquid–solid surface interfaces including the ability to increase the solubility of substances, lower the surface tension of a liquid, and decrease friction between two mediums. Because of these unique physical properties several in vitro, ex vivo, and human trials have examined the role of surfactants as stand-alone or adjunct therapy in recalcitrant chronic rhinosinusitis (CRS). Methods: A review of the literature was performed. Results: The data from three different surfactants have been examined in this review: citric acid zwitterionic surfactant (CAZS; Medtronic ENT, Jacksonville FL), Johnson's Baby Shampoo (Johnson & Johnson, New Brunswick NJ), and SinuSurf (NeilMed Pharmaceuticals, Santa Rosa, CA). Dilute surfactant therapy shows in vitro antimicrobial effects with modest inhibition of bacterial biofilm formation. In patients with CRS, surfactants may improve symptoms, most likely through its mucolytic effects. In addition, surfactants have several distinct potential benefits including their ability to improve an irrigant's penetration of the nonoperated sinus and their synergistic effects with antibiotics. However, surfactants potential for nasal irritation and possible transient ciliotoxicity may limit their use. Conclusion: Recent data suggest a possible therapeutic role of surfactants in treating rhinopathologies associated with mucostasis. Further investigation, including a standardization of surfactant formulations, is warranted to further elucidate the potential benefits and drawbacks of this therapy. PMID:23710951

  1. Inorganic chemically active adsorbents (ICAAs)

    SciTech Connect

    Ally, M.R.; Tavlarides, L.

    1997-10-01

    Oak Ridge National Laboratory (ORNL) researchers are developing a technology that combines metal chelation extraction technology and synthesis chemistry. They begin with a ceramic substrate such as alumina, titanium oxide or silica gel because they provide high surface area, high mechanical strength, and radiolytic stability. One preparation method involves silylation to hydrophobize the surface, followed by chemisorption of a suitable chelation agent using vapor deposition. Another route attaches newly designed chelating agents through covalent bonding by the use of coupling agents. These approaches provide stable and selective, inorganic chemically active adsorbents (ICAAs) tailored for removal of metals. The technology has the following advantages over ion exchange: (1) higher mechanical strength, (2) higher resistance to radiation fields, (3) higher selectivity for the desired metal ion, (4) no cation exchange, (5) reduced or no interference from accompanying anions, (6) faster kinetics, and (7) easy and selective regeneration. Target waste streams include metal-containing groundwater/process wastewater at ORNL`s Y-12 Plant (multiple metals), Savannah River Site (SRS), Rocky Flats (multiple metals), and Hanford; aqueous mixed wastes at Idaho National Engineering Laboratory (INEL); and scrubber water generated at SRS and INEL. Focus Areas that will benefit from this research include Mixed Waste, and Subsurface Contaminants.

  2. Photoacoustic spectra of malachite green adsorbed on silica gel surface

    NASA Astrophysics Data System (ADS)

    Sikorska, Anna; Zachara, Stanislaw

    1992-11-01

    Photoacoustic spectra of malachite green adsorbed on silica gel were investigated at high dye concentrations. The measurements were carried out for two markedly differing layer thicknesses of dyed silica. The ratio of maxima of two characteristic dye bands at (lambda) equals 620 nm and (lambda) equals 425 nm was chosen as an indicator of concentration dependent changes in the shapes of the photoacoustic spectra investigated. The comparison of experimental data with the theoretical model implies that the changes observed in the shape of the spectrum result first of all from the mechanism of the signal generation in inhomogeneous medium.

  3. Micellar-enhanced ultrafiltration and air stripping for surfactant-contaminant separation and surfactant reuse

    SciTech Connect

    Lipe, K.M.; Sabatini, D.A.; Hasegawa, M.A.; Harwell, J.H.

    1996-05-01

    Micellar-enhanced ultrafiltration (MEUF) and air stripping were evaluated for surfactant-contaminant separation and surfactant recovery. Two linear alkyl diphenyloxide disulfonate (DPDS) surfactants were evaluated with the contaminants naphthalene and trichloroethylene. A separation model developed from micellar partitioning principles showed a good correlation to batch MEUF studies, whereas flux analysis highlighted concentration polarization effects in relation to hydrophobe length. MEUF effectively concentrated the surfactant-contaminant system (93 to 99% retention); however, this did not result in surfactant-contaminant separation. Batch and continuous flow air stripping models were developed based upon air/water ratio, surfactant concentration, and micellar partitioning; model predictions were validated by experimental data. Sensitivity analyses illustrated the decline in contaminant-surfactant separation with increasing surfactant concentration (e.g., TCE removal efficiency declines from 83% to 37% as C-16 DPDS concentration increases from 0 to 55 mM). This effect is greater for more hydrophobic contaminants (naphthalene vs. TCE) and surfactants with greater solubilization potential (C16-DPDS vs. C-12 DPDS). The resulting design equations can account for this effect and thus properly size air strippers to achieve the desired removal efficiency in the presence of surfactant micelles. Proper selection and design of surfactant-contaminant separation and surfactant recovery systems are integral to optimizing surfactant-enhanced subsurface remediation.

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

    PubMed

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

    2003-06-15

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

  5. Preparation and Thermal Properties of Fatty Alcohol/Surfactant/Oil/Water Nanoemulsions and Their Cosmetic Applications.

    PubMed

    Okamoto, Toru; Tomomasa, Satoshi; Nakajima, Hideo

    2016-01-01

    Physicochemical properties of oil-in-water (O/W) emulsions containing fatty alcohols and surfactants have been investigated with the aim of developing new formulations that are less viscous and more transparent than conventional milky lotions, as well as for providing greater skin-improving effects. O/W-based creams can be converted to low viscosity milky lotions following their emulsification with a homogenizer at temperatures greater than the transition temperatures of their molecular assemblies (α-gel). The stability of the O/W emulsions evaluated in the current study increased as the transition temperatures of the molecular assemblies formed from their fatty alcohol and surfactant constituents increased. A decrease in the emulsion droplet size led to the formation of a new formulation, which was transparent in appearance and showed a very low viscosity. The absence of a molecular assembly (α-gel) formed by the fatty alcohol and surfactant molecules in the aqueous phase allowed for the formation of a stable transparent and low viscosity nanoemulsion. Furthermore, this decrease in droplet size led to an increase in the interfacial area of the emulsion droplets, with almost all of the fatty alcohol and surfactant molecules being adsorbed on the surfaces of the emulsion droplets. This was found to be important for preparing a stable transparent formulation. Notably, this new formulation exhibited high occlusivity, which was equivalent to that of an ordinary cosmetic milky lotion, and consequently provided high skin hydration. The nanoemulsion was destroyed following its application to the skin, which led to the release of the fatty alcohol and surfactant molecules from the surface of the nanoemulsion into the aqueous phase. These results therefore suggest that the fatty alcohol and surfactant molecules organized the molecular assembly (α-gel) and allowed for the reconstruction of the network structure.

  6. Preparation and Thermal Properties of Fatty Alcohol/Surfactant/Oil/Water Nanoemulsions and Their Cosmetic Applications.

    PubMed

    Okamoto, Toru; Tomomasa, Satoshi; Nakajima, Hideo

    2016-01-01

    Physicochemical properties of oil-in-water (O/W) emulsions containing fatty alcohols and surfactants have been investigated with the aim of developing new formulations that are less viscous and more transparent than conventional milky lotions, as well as for providing greater skin-improving effects. O/W-based creams can be converted to low viscosity milky lotions following their emulsification with a homogenizer at temperatures greater than the transition temperatures of their molecular assemblies (α-gel). The stability of the O/W emulsions evaluated in the current study increased as the transition temperatures of the molecular assemblies formed from their fatty alcohol and surfactant constituents increased. A decrease in the emulsion droplet size led to the formation of a new formulation, which was transparent in appearance and showed a very low viscosity. The absence of a molecular assembly (α-gel) formed by the fatty alcohol and surfactant molecules in the aqueous phase allowed for the formation of a stable transparent and low viscosity nanoemulsion. Furthermore, this decrease in droplet size led to an increase in the interfacial area of the emulsion droplets, with almost all of the fatty alcohol and surfactant molecules being adsorbed on the surfaces of the emulsion droplets. This was found to be important for preparing a stable transparent formulation. Notably, this new formulation exhibited high occlusivity, which was equivalent to that of an ordinary cosmetic milky lotion, and consequently provided high skin hydration. The nanoemulsion was destroyed following its application to the skin, which led to the release of the fatty alcohol and surfactant molecules from the surface of the nanoemulsion into the aqueous phase. These results therefore suggest that the fatty alcohol and surfactant molecules organized the molecular assembly (α-gel) and allowed for the reconstruction of the network structure. PMID:26743668

  7. Preparation of nanocrystalline MgO by surfactant assisted precipitation method

    SciTech Connect

    Rezaei, Mehran; Khajenoori, Majid; Nematollahi, Behzad

    2011-10-15

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

  8. Charged nanoparticles as supramolecular surfactants for controlling the growth and stability of microcrystals

    NASA Astrophysics Data System (ADS)

    Kowalczyk, Bartlomiej; Bishop, Kyle J. M.; Lagzi, Istvan; Wang, Dawei; Wei, Yanhu; Han, Shuangbing; Grzybowski, Bartosz A.

    2012-03-01

    Microcrystals of desired sizes are important in a range of processes and materials, including controlled drug release, production of pharmaceutics and food, bio- and photocatalysis, thin-film solar cells and antibacterial fabrics. The growth of microcrystals can be controlled by a variety of agents, such as multivalent ions, charged small molecules, mixed cationic-anionic surfactants, polyelectrolytes and other polymers, micropatterned self-assembled monolayers, proteins and also biological organisms during biomineralization. However, the chief limitation of current approaches is that the growth-modifying agents are typically specific to the crystalizing material. Here, we show that oppositely charged nanoparticles can function as universal surfactants that control the growth and stability of microcrystals of monovalent or multivalent inorganic salts, and of charged organic molecules. We also show that the solubility of the microcrystals can be further tuned by varying the thickness of the nanoparticle surfactant layers and by reinforcing these layers with dithiol crosslinks.

  9. Infrared Analysis Of Enzymes Adsorbed Onto Model Surfaces

    NASA Astrophysics Data System (ADS)

    Story, Gloria M.; Rauch, Deborah S.; Brode, Philip F.; Marcott, Curtis A.

    1989-12-01

    The adsorption of the enzymes, subtilisin BPN' and lysozyme, onto model surfaces was examined using attenuated total reflectance (ATR) infrared (IR) spectroscopy. Using a cylindrical internal reflection (CIRcle) cell with a Germanium (Ge) internal reflection element (IRE), model hydrophilic surfaces were made by plasma cleaning the IRE and model hydrophobic surfaces were made by precoating the IRE with a thin film of polystyrene. Gas chromatography (GC)-IR data collection software was used to monitor adsorption kinetics during the first five minutes after injection of the enzyme into the CIRcle cell. It was found that for both lysozyme and BPN', most of the enzyme that was going to adsorb onto the model surface did so within ten seconds after injection. Nearly an order-of-magnitude more BPN' adsorbed on the hydrophobic Ge surface than the hydrophilic one, while lysozyme adsorbed somewhat more strongly to the hydrophilic Ge surface. Overnight, the lysozyme layer continued to increase in thickness, while BPN' maintained its initial coverage. The appearance of carboxylate bands in some of the adsorbed BPN' spectra suggests the occurrence of peptide bond hydrolysis. A Au/Pd coating on the CIRcle cell o-rings had a significant effect on the adsorption of BPN'. (This coating was applied in an attempt to eliminate interfering Teflon absorption bands.) An apparent electrochemical reaction occurred, involving BPN', Ge, Au/Pd, and the salt solution used to stabilize BPN'. The result of this reaction was enhanced adsorption of the enzyme around the coated o-rings, etching of the Ge IRE at the o-ring site, and some autolysis of the enzyme. No such reaction was observed with lysozyme.

  10. Hydrodynamic size of DNA/cationic gemini surfactant complex as a function of surfactant structure.

    PubMed

    Devínsky, Ferdinand; Pisárcik, Martin; Lacko, Ivan

    2009-06-01

    The present study deals with the determination of hydrodynamic size of DNA/cationic gemini surfactant complex in sodium bromide solution using the dynamic light scattering method. Cationic gemini surfactants with polymethylene spacer of variable length were used for the interaction with DNA. The scattering experiments were performed at constant DNA and sodium bromide concentrations and variable surfactant concentration in the premicellar and micellar regions as a function of surfactant spacer length. It was found that the DNA conformation strongly depends on the polymethylene spacer length as well as on the surfactant concentration relative to the surfactant critical micelle concentration. Gemini surfactant molecules with 4 methylene groups in the spacer were found to be the least efficient DNA compacting agent in the region above the surfactant cmc. Gemini molecules with the shortest spacer length (2 methylene groups) and the longest spacer length (8 methylene groups) investigated showed the most efficient DNA compaction ability. PMID:19592712

  11. A new nano-engineered hierarchical membrane for concurrent removal of surfactant and oil from oil-in-water nanoemulsion

    NASA Astrophysics Data System (ADS)

    Qin, Detao; Liu, Zhaoyang; Bai, Hongwei; Sun, Darren Delai; Song, Xiaoxiao

    2016-04-01

    Surfactant stabilized oil-in-water nanoemulsions pose a severe threat to both the environment and human health. Recent development of membrane filtration technology has enabled efficient oil removal from oil/water nanoemulsion, however, the concurrent removal of surfactant and oil remains unsolved because the existing filtration membranes still suffer from low surfactant removal rate and serious surfactant-induced fouling issue. In this study, to realize the concurrent removal of surfactant and oil from nanoemulsion, a novel hierarchically-structured membrane is designed with a nanostructured selective layer on top of a microstructured support layer. The physical and chemical properties of the overall membrane, including wettability, surface roughness, electric charge, thickness and structures, are delicately tailored through a nano-engineered fabrication process, that is, graphene oxide (GO) nanosheet assisted phase inversion coupled with surface functionalization. Compared with the membrane fabricated by conventional phase inversion, this novel membrane has four times higher water flux, significantly higher rejections of both oil (~99.9%) and surfactant (as high as 93.5%), and two thirds lower fouling ratio when treating surfactant stabilized oil-in-water nanoemulsion. Due to its excellent performances and facile fabrication process, this nano-engineered membrane is expected to have wide practical applications in the oil/water separation fields of environmental protection and water purification.

  12. A new nano-engineered hierarchical membrane for concurrent removal of surfactant and oil from oil-in-water nanoemulsion.

    PubMed

    Qin, Detao; Liu, Zhaoyang; Bai, Hongwei; Sun, Darren Delai; Song, Xiaoxiao

    2016-01-01

    Surfactant stabilized oil-in-water nanoemulsions pose a severe threat to both the environment and human health. Recent development of membrane filtration technology has enabled efficient oil removal from oil/water nanoemulsion, however, the concurrent removal of surfactant and oil remains unsolved because the existing filtration membranes still suffer from low surfactant removal rate and serious surfactant-induced fouling issue. In this study, to realize the concurrent removal of surfactant and oil from nanoemulsion, a novel hierarchically-structured membrane is designed with a nanostructured selective layer on top of a microstructured support layer. The physical and chemical properties of the overall membrane, including wettability, surface roughness, electric charge, thickness and structures, are delicately tailored through a nano-engineered fabrication process, that is, graphene oxide (GO) nanosheet assisted phase inversion coupled with surface functionalization. Compared with the membrane fabricated by conventional phase inversion, this novel membrane has four times higher water flux, significantly higher rejections of both oil (~99.9%) and surfactant (as high as 93.5%), and two thirds lower fouling ratio when treating surfactant stabilized oil-in-water nanoemulsion. Due to its excellent performances and facile fabrication process, this nano-engineered membrane is expected to have wide practical applications in the oil/water separation fields of environmental protection and water purification. PMID:27087362

  13. A new nano-engineered hierarchical membrane for concurrent removal of surfactant and oil from oil-in-water nanoemulsion

    PubMed Central

    Qin, Detao; Liu, Zhaoyang; Bai, Hongwei; Sun, Darren Delai; Song, Xiaoxiao

    2016-01-01

    Surfactant stabilized oil-in-water nanoemulsions pose a severe threat to both the environment and human health. Recent development of membrane filtration technology has enabled efficient oil removal from oil/water nanoemulsion, however, the concurrent removal of surfactant and oil remains unsolved because the existing filtration membranes still suffer from low surfactant removal rate and serious surfactant-induced fouling issue. In this study, to realize the concurrent removal of surfactant and oil from nanoemulsion, a novel hierarchically-structured membrane is designed with a nanostructured selective layer on top of a microstructured support layer. The physical and chemical properties of the overall membrane, including wettability, surface roughness, electric charge, thickness and structures, are delicately tailored through a nano-engineered fabrication process, that is, graphene oxide (GO) nanosheet assisted phase inversion coupled with surface functionalization. Compared with the membrane fabricated by conventional phase inversion, this novel membrane has four times higher water flux, significantly higher rejections of both oil (~99.9%) and surfactant (as high as 93.5%), and two thirds lower fouling ratio when treating surfactant stabilized oil-in-water nanoemulsion. Due to its excellent performances and facile fabrication process, this nano-engineered membrane is expected to have wide practical applications in the oil/water separation fields of environmental protection and water purification. PMID:27087362

  14. Interactions between kappa-carrageenan and some surfactants in the bulk solution and at the surface of alumina.

    PubMed

    Grządka, E

    2015-06-01

    The interactions between surfactants (SDS, CTAB, TX-100 or their equimolar mixtures) and kappa-carrageenan (Carr) in the bulk solution and at the surface of alumina were determined using the surface tension and the spectrophotometric adsorption measurements. The obtained results show that Carr has the ability to create the multilayer complexes with CTAB, TX-100 and the equimolar mixtures of surfactants (CTAB/TX-100), but does not interact with SDS. The created complexes are electrostatic (with CTAB) or they are of different mechanisms such as the hydrogen bonding or the acid-base interactions (with TX-100). The electrokinetic measurements (the surface charge density and the zeta potential) allow to analyze the structure of the adsorption layer: polymer/surfactant/metal oxide. It turned out that the macromolecules of Carr are directly bonded to the surface whereas the surfactants are present in the upper parts of the electrical double layer.

  15. Enhancing Dopant Solubility via Epitaxial Surfactant Growth

    SciTech Connect

    Zhang, L.; Yan, Y.; Wei, S.-H.

    2009-01-01

    A general concept for enhancing dopant solubility via epitaxial surfactant growth is proposed. The key of the concept is to find the appropriate surfactants that generate high (low) levels that can transfer electrons (holes) to dopant acceptor (donor) levels in p-type (n-type) doping, thus significantly lowering the formation energy of dopants. Using first-principles density-functional calculations, our concept explains excellently the recently discovered dual-surfactant effect of Sb and H on enhancing Zn doping in epitaxially grown GaP(100) thin film and suggests that sole surfactant Te can also induce enhancement of N solubility in ZnSe(100) film. We also proposed the surfactants for enhancing p-type doing of ZnO with epitaxial growth with (000{bar 1}) surface. General rules for selecting surfactants for enhancing both p-type and n-type dopings are provided.

  16. Adsorbed natural gas storage with activated carbon

    SciTech Connect

    Sun, Jian; Brady, T.A.; Rood, M.J.

    1996-12-31

    Despite technical advances to reduce air pollution emissions, motor vehicles still account for 30 to 70% emissions of all urban air pollutants. The Clean Air Act Amendments of 1990 require 100 cities in the United States to reduce the amount of their smog within 5 to 15 years. Hence, auto emissions, the major cause of smog, must be reduced 30 to 60% by 1998. Natural gas con be combusted with less pollutant emissions. Adsorbed natural gas (ANG) uses adsorbents and operates with a low storage pressure which results in lower capital costs and maintenance. This paper describes the production of an activated carbon adsorbent produced from an Illinois coal for ANG.

  17. States of water adsorbed on perindopril crystals

    NASA Astrophysics Data System (ADS)

    Stepanov, V. A.; Khmelevskaya, V. S.; Bogdanov, N. Yu.; Gorchakov, K. A.

    2011-10-01

    The relationship between the structural state of adsorbed water, the crystal structure of the substances, and the solubility of the perindopril salt C19H32N2O5 · C4H11N in water was studied by IR spectroscopy and X-ray diffractometry. The high-frequency shift of the stretching vibrations of adsorbed water and the solubility depend on the crystal structure of the drug substance. A reversible chemical reaction occurred between the adsorbed water and the perindopril salt.

  18. Critical roles of cationic surfactants in the preparation of colloidal mesostructured silica nanoparticles: control of mesostructure, particle size, and dispersion.

    PubMed

    Yamada, Hironori; Urata, Chihiro; Higashitamori, Sayuri; Aoyama, Yuko; Yamauchi, Yusuke; Kuroda, Kazuyuki

    2014-03-12

    Mesoporous silica nanoparticles are promising materials for various applications, such as drug delivery and catalysis, but the functional roles of surfactants in the formation and preparation of mesostructured silica nanoparticles (MSN-as) remain to be seen. It was confirmed that the molar ratio of cationic surfactants to Si of alkoxysilanes (Surf/Si) can affect the degree of mesostructure formation (i.e., whether the mesochannels formed inside the nanoparticles actually pass through the outer surface of the particles), the particle diameter, and the dispersibility of MSN-as. Wormhole-like mesostructures formed with low Surf/Si ratios; however, the mesopores did not pass through the outer surface of the particles completely. At high Surf/Si ratios, the mesostructures extended. The particle diameter was 100 nm or larger at low Surf/Si ratios, and the primary particle diameter decreased as the Surf/Si ratio increased. This was because the surfactants enhanced the dispersity of the alkoxysilanes in water and the hydrolysis rate of the alkoxysilanes became faster, leading to an increased nucleation as compared to the particle growth. Moreover, primary particles aggregated at low Surf/Si ratios because of the hydrophobic interactions among the surfactants that were not involved in the mesostructure formation but were adsorbed onto the nanoparticles. At high Surf/Si ratios, the surfactant micelles were adsorbed on the surface of primary particles (admicelles), resulting in the dispersion of the particles due to electrostatic repulsion. In particular, molar ratios of 0.13 or higher were quite effective for the preparation of highly dispersed MSN-as. Surfactants played important roles in the mesostructure formation, decreasing the particle diameters, and the dispersibility of the particles. All of these factors were considerably affected by the Surf/Si ratio. The results suggested novel opportunities to control various colloidal mesostructured nanoparticles from the

  19. Ion exchangers as adsorbents for removing metals from aquatic media.

    PubMed

    Khan, Meraj A; Bushra, Rani; Ahmad, Anees; Nabi, Syed A; Khan, Dilwar A; Akhtar, Arshia

    2014-02-01

    A polyaniline-based composite cation-exchange material was synthesized by way of sol-gel method and studied to explore its analytical and environmental applications. It was characterized by using instrumental analyses [Fourier transform infrared (spectrometer), X-ray, thermogravimetric analysis/differential thermal analysis, standard electron microscopy, and transmission electron microscopy]. Physicochemical studies, such as ion-exchange capacity, pH titrations, and chemical stability, along with effect of eluent concentration and elution, were also performed to exploit the ion-exchange capabilities. pH titration studies showed that the material presents monofunctional strong cation-exchange behavior. This nanocomposite material is semicrystalline in nature and exhibits improved thermal and chemical stability. The partition coefficient studies of different metal ions in the material were performed in demineralised water and different surfactant media, and it was found to be selective for Pb(II) and Hg(II) ions. To exploit the usefulness of the material as an adsorbent, some important quantitative binary separations of metal ions were performed on polyaniline Zr(IV) molybdophosphate columns. This composite cation exchanger can be applied for the treatment of polluted water to remove heavy metals. PMID:24292693

  20. Mysterious Lattice Rotations in Adsorbed Monolayers

    NASA Astrophysics Data System (ADS)

    Diehl, Renee D.

    1997-03-01

    Lattice rotations due to a mismatch in structure have been observed in film growth for many years, probably beginning in the 1930's with the Nishiyama-Wasserman and Kurdjumov-Sachs orientations observed when fcc(111) films grow on bcc(110) surfaces, or vice versa. Early analysis of this problem was carried out with the aid of Moiré patterns and the observation that the preferred lattice orientations are those which maximize the Moiré fringe spacing. Later energy calculations indicated that the structures which were predicted by the the Moiré technique actually do correspond to energy minima. Epitaxial rotation in adsorbed monolayers is a conceptually simpler problem since in principle it involves only two planes of atoms, and it was first observed in 1977 for Ar on a graphite surface(C. G. Shaw, M. D. Chinn, S. C. Fain, Jr. Phys. Rev. Lett. 41 (1978) 955.). This observation came only a few months after a new theory, based on the expected elastic behavior of an overlayer, was developed by A. D. Novaco and J. P. McTague(A. D. Novaco and J. P. McTague, Phys. Rev. Lett. 38 (1977) 1286.), and the agreement with the experimental results was remarkable. It was later shown that a few symmetry principles similar to those used for the film growth studies sometimes can also predict the observed structures. However, the situation for incommensurate layers physisorbed on metal surfaces currently looks bleak. None of the existing theories or models appears to describe the experimental results. New data for physisorbed gases on metal surfaces will be presented, along with some half-baked (and probably wrong) ideas for what might be happening. This work was supported by NSF.

  1. Cationic versus anionic surfactant in tuning the structure and interaction of nanoparticle, protein, and surfactant complexes.

    PubMed

    Mehan, Sumit; Aswal, Vinod K; Kohlbrecher, Joachim

    2014-08-26

    The structure and interaction in complexes of anionic Ludox HS40 silica nanoparticle, anionic bovine serum albumin (BSA) protein, and cationic dodecyl trimethylammonium bromide (DTAB) surfactant have been studied using small-angle neutron scattering (SANS). The results are compared with similar complexes having anionic sodium dodecyl sulfate (SDS) surfactant (Mehan, S; Chinchalikar, A. J.; Kumar, S.; Aswal, V. K.; Schweins, R. Langmuir 2013, 29, 11290). In both cases (DTAB and SDS), the structure in nanoparticle-protein-surfactant complexes is predominantly determined by the interactions of the individual two-component systems. The nanoparticle-surfactant (mediated through protein-surfactant complex) and protein-surfactant interactions for DTAB, but nanoparticle-protein (mediated through protein-surfactant complex) and protein-surfactant interactions for SDS, are found to be responsible for the resultant structure of nanoparticle-protein-surfactant complexes. Irrespective of the charge on the surfactant, the cooperative binding of surfactant with protein leads to micellelike clusters of surfactant formed along the unfolded protein chain. The adsorption of these protein-surfactant complexes for DTAB on oppositely charged nanoparticles gives rise to the protein-surfactant complex-mediated aggregation of nanoparticles (similar to that of DTAB surfactant). It is unlike that of depletion-induced aggregation of nanoparticles with nonadsorption of protein-surfactant complexes for SDS in similarly charged nanoparticle systems (similar to that of protein alone). The modifications in nanoparticle aggregation as well as unfolding of protein in these systems as compared to the corresponding two-component systems have also been examined by selectively contrast matching the constituents.

  2. Oscillations of Bubble Shape Cause Anomalous Surfactant Diffusion: Experiments, Theory, and Simulations.

    PubMed

    Raudino, Antonio; Raciti, Domenica; Grassi, Antonio; Pannuzzo, Martina; Corti, Mario

    2016-08-30

    We investigate, both theoretically and experimentally, the role played by the oscillations of the cell membrane on the capture rate of substances freely diffusing around the cell. To obtain quantitative results, we propose and build up a reproducible and tunable biomimetic experimental model system to simulate the phenomenon of an oscillation-enhanced (or depressed) capture rate (chemoreception) of a diffusant. The main advantage compared to real biological systems is that the different oscillation parameters (type of deformation, frequencies, and amplitudes) can be finely tuned. The model system that we use is an anchored gas drop submitted to a diffusive flow of charged surfactants. When the surfactant meets the surface of the bubble, it is reversibly adsorbed. Bubble oscillations of the order of a few nanometers are selectively excited, and surfactant transport is accurately measured. The surfactant concentration past the oscillating bubbles was detected by conductivity measurements. The results highlight the role of surface oscillations on the diffusant capture rate. Particularly unexpected is the onset of intense overshoots during the adsorption process. The phenomenon is particularly relevant when the bubbles are exposed to intense forced oscillations near resonance. PMID:27509197

  3. Clay swelling and formation permeability reductions induced by a nonionic surfactant

    SciTech Connect

    Gardner, K.H.; Arias, M.S.

    2000-01-01

    A major concern with the use of surfactant flushing to mobilize nonaqueous phase liquids in aquifers is specific mineral-surfactant interactions that may effect significant permeability changes in the soil formation. Soils comprised of Ottawa sand mixed with small percentages of bentonite that had moderate initial hydraulic conductivity were investigated for loss of permeability upon flushing with solution containing a nonionic surfactant (polyoxyethylene sorbitan monooleate). Columns containing 0, 1, 2, 3, 4, and 5% had permeability reductions of 1, 5, 13, 44, 49, and 69%, respectively. The surfactant-clay interactions were further investigated as the cause of the permeability reductions. Some transport of clay through the column was apparent from a small amount of release measured. A permeability change was correlated with the colloid transport in the column with the highest clay concentration, although its effect was transient. Clay swelling was postulated as the primary mechanism for the permeability reductions. It was determined through X-ray diffraction that the surfactant was spreading the silica layer spacings of the clay from a hydration spacing of 15.23 {angstrom} to a surfactant-swelled spacing of 18.02 {angstrom}. A model was formulated to describe the reduced permeability by the increase in clay volume due to swelling measured by X-ray diffraction and was capable of describing the observed data well with an average error of approximately 10%.

  4. Enhanced Surfactant Adsorption on Activated Carbon through Manipulation of Surface Oxygen Groups

    NASA Astrophysics Data System (ADS)

    Collins, John; Qu, Deyang; Foster, Michelle

    2012-02-01

    Passive energy storage is a necessary component for balancing the lifecycle budget with new forms of green energy. The work presented describes how surface oxygen groups (SOG) on granulated activated carbon have been manipulated using Nitric Acid in a controlled, stepwise fashion. The structure and surface functionality of the activated carbon samples were characterized using DRIFTS, Raman Spectroscopy and Porosimetry. Total surface area was found to increase proportionally with the removal of heteroatom material, exposing previously insulated active sites responsible for SOG attachment. Broad oxide peaks were deconvoluted and analyzed, allowing for absolute identification of evolving functionality at each oxidation stage. SOGs were maximized on the third oxidation cycle with the presence of conjugated aromatic, phenol, lactone, and carboxylic acid groups. FSN Zonyl nonionic was applied to all oxidized samples at various concentrations. Total adsorbed surfactant was quantified for each concentration / oxidation scheme using attenuated total reflection. The relative quantity and polarity of chemisorbed surfactant were qualitatively assessed for each equilibrium concentration.

  5. Biophysical inhibition of pulmonary surfactant function by polymeric nanoparticles: role of surfactant protein B and C.

    PubMed

    Beck-Broichsitter, Moritz; Ruppert, Clemens; Schmehl, Thomas; Günther, Andreas; Seeger, Werner

    2014-11-01

    The current study investigated the mechanisms involved in the process of biophysical inhibition of pulmonary surfactant by polymeric nanoparticles (NP). The minimal surface tension of diverse synthetic surfactants was monitored in the presence of bare and surface-decorated (i.e. poloxamer 407) sub-100 nm poly(lactide) NP. Moreover, the influence of NP on surfactant composition (i.e. surfactant protein (SP) content) was studied. Dose-elevations of SP advanced the biophysical activity of the tested surfactant preparation. Surfactant-associated protein C supplemented phospholipid mixtures (PLM-C) were shown to be more susceptible to biophysical inactivation by bare NP than phospholipid mixture supplemented with surfactant protein B (PLM-B) and PLM-B/C. Surfactant function was hindered owing to a drastic depletion of the SP content upon contact with bare NP. By contrast, surface-modified NP were capable of circumventing unwanted surfactant inhibition. Surfactant constitution influences the extent of biophysical inhibition by polymeric NP. Steric shielding of the NP surface minimizes unwanted NP-surfactant interactions, which represents an option for the development of surfactant-compatible nanomedicines.

  6. Immiscible displacement of oil with surfactant system

    SciTech Connect

    Shaw, J. E.

    1985-12-03

    In accordance with the present invention it has been found that improved recovery of oil from a subsurface earth formation can be attained by injecting into the formation a surfactant system comprising a carboxylate surfactant, a cosurfactant and an electrolyte in concentrations and proportions to form an immiscible three-phase system with the reservoir oil comprising a predominantly oil phase, a microemulsion phase and an aqueous phase. The carboxylate surfactant is preferably selected from the group consisting of branched aliphatic carboxylates and mononuclear aromatic carboxylates. Where aliphatic carboxylates are utilized as a surfactant, it is preferred that the polar organic material utilized as a cosurfactant have a solubility in water less than about ten grams per hundred grams of water ost about 20/sup 0/ C. and, when an aromatic carboxylate is utilized as a surfactant, it is preferred that the polar organic material utilized as a cosurfactant have a water solubility greater than about ten grams per hundred grams of water at about 20/sup 0/ C. In accordance with another aspect of the present invention, it has been found that surfactant systems containing carboxylate surfactants will recover optimum amounts of oil when a base is added to the surfactant system to adjust the pH to a value at which the surfactant system results nin optimum oil recovery.

  7. Adsorbed Proteins Influence the Biological Activity and Molecular Targeting of Nanomaterials

    SciTech Connect

    Dutta, Debamitra; Sundaram, S. K.; Teeguarden, Justin G.; Riley, Brian J.; Fifield, Leonard S.; Jacobs, Jon M.; Addleman, Raymond S.; Kaysen, George A.; Moudgil, Brij M.; Weber, Thomas J.

    2007-11-01

    The possible combination of unique physicochemical properties operating at unique sites of action within cells and tissues has led to considerable uncertainty surrounding nanomaterial toxic potential. Here we have investigated the relative importance of proteins adsorbed onto nanomaterial surfaces in guiding uptake and toxicity to determine whether a priori identification of adsorbed proteins will contribute to nanomaterial toxicity assessment. Albumin was identified as the major protein adsorbed onto single walled carbon nanotubes (SWCNTs) following incubation with fetal bovine or human serum/plasma, but not when plasma from the Nagase Analbuminemic Rat (NAR) was used, and precoating SWCNTs with a non-ionic surfactant (Pluronic F127) inhibited albumin adsorption. Damaged or structurally altered albumin is rapidly cleared by scavenger receptors. In the RAW 264.7 macrophage-like model, we observed that SWCNTs inhibited the induction of cyclooxygenase-2 (Cox-2) by lipopolysaccharide (LPS; 1 ng/ml, 6 hr) and this anti-inflammatory response was inhibited by fucoidan (scavenger receptor antagonist) and by precoating SWCNTs with Pluronic F127. Fucoidan also reduced the uptake of fluorescent SWCNTs (Alexa647) in RAW 264.7 cells. Albumin-coated SWCNTs reduced LPS-mediated Cox-2 induction. SWCNTs did not appear to reduce binding of a fluorescent LPS (Alexa488) to RAW 264.7 cells. The profile of proteins adsorbed onto amorphous silica (50 – 1000 nm) was qualitatively different, relative to SWCNTs, and coating amorphous silica with Pluronic F127 dramatically reduced protein binding and toxicity. Collectively, these observations are consistent with an important role for adsorbed proteins in guiding nanomaterial disposition and toxicity.

  8. PERVAPORATION USING ADSORBENT-FILLED MEMBRANES

    EPA Science Inventory

    Membranes containing selective fillers, such as zeolites and activated carbon, can improve the separation by pervaporation. Applications of adsorbent-filled membranes in pervaporation have been demonstrated by a number of studies. These applications include removal of organic co...

  9. Molecular dynamics simulations of SDS, DTAB, and C12E8 monolayers adsorbed at the air/water surface in the presence of DSEP.

    PubMed

    Pang, Jinyu; Wang, Yajing; Xu, Guiying; Han, Tingting; Lv, Xin; Zhang, Jian

    2011-03-24

    The properties of adsorbed monolayers of three hydrocarbon surfactants with the same hydrophobic tail, sodium dodecyl sulfate (SDS), dodecyltrimethylammonium bromide (DTAB) and octaethylene glycol dodecyl ether (C(12)E(8)) at the air/water surface in the absence and presence of a dimethylsiloxane ethoxylate-propoxylate (DSEP) were studied via molecular dynamics simulations to compare the effect of the headgroups on the aggregation behaviors of surfactant mixtures. The structures and dynamical properties of the monolayers were greatly affected after adding DSEP. In the presence of DSEP, SDS monolayer was better ordered and more compact, whereas C(12)E(8) monolayer was relatively disordered. Some DTAB molecules immerged into water, and the others adsorbed at the surface were in less compact but well-ordered arrangement. The reason for the appearance of different types of monolayers was also discussed, with the goal of providing a theoretical approach for their further applications.

  10. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, Sheldon H. D.

    1992-01-01

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases.

  11. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, S.H.D.

    1992-12-22

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases. 6 figs.

  12. Mesoporous Silica: A Suitable Adsorbent for Amines

    PubMed Central

    2009-01-01

    Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices. PMID:20628459

  13. Hydrophobic Porous Material Adsorbs Small Organic Molecules

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K.; Hickey, Gregory S.

    1994-01-01

    Composite molecular-sieve material has pore structure designed specifically for preferential adsorption of organic molecules for sizes ranging from 3 to 6 angstrom. Design based on principle that contaminant molecules become strongly bound to surface of adsorbent when size of contaminant molecules is nearly same as that of pores in adsorbent. Material used to remove small organic contaminant molecules from vacuum systems or from enclosed gaseous environments like closed-loop life-support systems.

  14. Neutron Reflection Study of Bovine β-Casein Adsorbed on OTS Self- Assembled Monolayers

    NASA Astrophysics Data System (ADS)

    Fragneto, Giovanna; Thomas, Robert K.; Rennie, Adrian R.; Penfold, Jeffrey

    1995-02-01

    Specular neutron reflection has been used to determine the structure and composition of bovine β-casein adsorbed on a solid surface from an aqueous phosphate-buffered solution at pH 7. The protein was adsorbed on a hydrophobic monolayer self-assembled from deuterated octadecyltrichlorosilane solution on a silicon (111) surface. A two-layer structure formed consisting of one dense layer of thickness 23 ± 1 angstroms and a surface coverage of 1.9 milligrams per square meter adjacent to the surface and an external layer protruding into the solution of thickness 35 ± 1 angstroms and 12 percent protein volume fraction. The structure of the (β-casein) layer is explained in terms of the charge distribution in the protein.

  15. Shear rheology of mixed protein adsorption layers vs their structure studied by surface force measurements.

    PubMed

    Danov, Krassimir D; Kralchevsky, Peter A; Radulova, Gergana M; Basheva, Elka S; Stoyanov, Simeon D; Pelan, Eddie G

    2015-08-01

    The hydrophobins are proteins that form the most rigid adsorption layers at liquid interfaces in comparison with all other investigated proteins. The mixing of hydrophobin HFBII with other conventional proteins is expected to reduce the surface shear elasticity and viscosity, E(sh) and η(sh), proportional to the fraction of the conventional protein. However, the experiments show that the effect of mixing can be rather different depending on the nature of the additive. If the additive is a globular protein, like β-lactoglobulin and ovalbumin, the surface rigidity is preserved, and even enhanced. The experiments with separate foam films indicate that this is due to the formation of a bilayer structure at the air/water interface. The more hydrophobic HFBII forms the upper layer adjacent to the air phase, whereas the conventional globular protein forms the lower layer that faces the water phase. Thus, the elastic network formed by the adsorbed hydrophobin remains intact, and even reinforced by the adjacent layer of globular protein. In contrast, the addition of the disordered protein β-casein leads to softening of the HFBII adsorption layer. Similar (an even stronger) effect is produced by the nonionic surfactant Tween 20. This can be explained with the penetration of the hydrophobic tails of β-casein and Tween 20 between the HFBII molecules at the interface, which breaks the integrity of the hydrophobin interfacial elastic network. The analyzed experimental data for the surface shear rheology of various protein adsorption layers comply with a viscoelastic thixotropic model, which allows one to determine E(sh) and η(sh) from the measured storage and loss moduli, G' and G″. The results could contribute for quantitative characterization and deeper understanding of the factors that control the surface rigidity of protein adsorption layers with potential application for the creation of stable foams and emulsions with fine bubbles or droplets.

  16. Giant Hysteresis of Single-Molecule Magnets Adsorbed on a Nonmagnetic Insulator.

    PubMed

    Wäckerlin, Christian; Donati, Fabio; Singha, Aparajita; Baltic, Romana; Rusponi, Stefano; Diller, Katharina; Patthey, François; Pivetta, Marina; Lan, Yanhua; Klyatskaya, Svetlana; Ruben, Mario; Brune, Harald; Dreiser, Jan

    2016-07-01

    TbPc2 single-molecule magnets adsorbed on a magnesium oxide tunnel barrier exhibit record magnetic remanence, record hysteresis opening, perfect out-of-plane alignment of the magnetic easy axes, and self-assembly into a well-ordered layer. PMID:27159732

  17. Giant Hysteresis of Single-Molecule Magnets Adsorbed on a Nonmagnetic Insulator.

    PubMed

    Wäckerlin, Christian; Donati, Fabio; Singha, Aparajita; Baltic, Romana; Rusponi, Stefano; Diller, Katharina; Patthey, François; Pivetta, Marina; Lan, Yanhua; Klyatskaya, Svetlana; Ruben, Mario; Brune, Harald; Dreiser, Jan

    2016-07-01

    TbPc2 single-molecule magnets adsorbed on a magnesium oxide tunnel barrier exhibit record magnetic remanence, record hysteresis opening, perfect out-of-plane alignment of the magnetic easy axes, and self-assembly into a well-ordered layer.

  18. Multilayers at the surface of solutions of exogenous lung surfactant: direct observation by neutron reflection.

    PubMed

    Follows, D; Tiberg, F; Thomas, R K; Larsson, M

    2007-02-01

    Pharmacy-grade exogenous lung surfactant preparations of bovine and porcine origin, dispersed in physiological electrolyte solution have been studied. The organization and dynamics at the air/water interface at physiological temperature was analysed by neutron reflection. The results show that a well-defined surface phase is formed, consisting of a multilayer structure of lipid/protein bilayers alternating with aqueous layers, with a repetition period of about 70 A and correlation depths of 3 to >25 bilayers, depending on electrolyte composition and time. The experimental surfactant concentration of 0.15% (w/w) is far below that used in therapeutic application of exogenous surfactants and it is therefore likely that similar multilayer structures are also formed at the alveolar surface in the clinical situation during surfactant substitution therapy. Lung surfactant preparations in dry form swell in aqueous solution towards a limit of about 60% (w/w) of water, forming a lamellar liquid-crystalline phase above about 34 degrees C, which disperses into lamellar bodies at higher water concentrations. The lamellar spacings in the surface multilayers at the air/water interface are smaller than those in the saturated limit even though they are in contact with much greater water concentrations. The surface multilayers are laterally disordered in a way that is consistent with fragments of Lalpha-phase lamellae. The near surface layers of the multilayer structure have a significant protein content (only SP-B and SP-C are present in the preparations). The results demonstrate that a multilayer structure can be formed in exogenous surfactant even at very low concentrations and indicate that multilayers need to be incorporated into present interpretations of in vitro studies of similar lung surfactant preparations, which are largely based on monolayer models.

  19. Study of Asorption Kinetics of Surfactants onto Polyethersulfone Membrane Surface Using QCM-D

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The adsorption kinetics of surfactants onto the crystal surface spin-coated with a thin layer of a model membrane material, polyethersulfone was monitored through measurements of frequency and dissipation shifts simultaneously using a quartz crystal microbalance with dissipation (QCM-D) device. In ...

  20. Surface properties of mesoporous carbon-silica gel adsorbents

    SciTech Connect

    Leboda, R.; Turov, V.V.; Charmas, B.; Skubiszewska-Zieba, J.; Gun'ko, V.M.

    2000-03-01

    Carbon/silica (carbosil) samples prepared utilizing mesoporous silica gel (Si-60) modified by methylene chloride pyrolysis were studied by nitrogen adsorption, quasi-isothermal thermogravimetry, p-nitrophenol adsorption from aqueous solution, and {sup 1}H NMR methods. The structural characteristics and other properties of carbosils depend markedly on the synthetic conditions and the amount of carbon deposited. The changes in the pore size distribution with increasing carbon concentration suggest grafting of carbon mainly in pores, leading to diminution of the mesopore radii. However, heating pure silica gel at the pyrolysis temperature of 550 C leads to an increase in the pore radii. The quasi-isothermal thermogravimetry and {sup 1}H NMR spectroscopy methods used to investigate the water layers on carbosils showed a significant capability of carbosils to adsorb water despite a relatively large content of the hydrophobic carbon deposit, which represents a nonuniform layer incompletely covering the oxide surface.

  1. Enhanced removal of radioactive particles by fluorocarbon surfactant solutions

    SciTech Connect

    Kaiser, R.; Harling, O.K.

    1993-08-01

    The proposed research addressed the application of ESI`s particle removal process to the non-destructive decontamination of nuclear equipment. The cleaning medium used in this process is a solution of a high molecular weight fluorocarbon surfactant in an inert perfluorinated liquid which results in enhanced particle removal. The perfluorinated liquids of interest, which are recycled in the process, are nontoxic, nonflammable, and environmentally compatible, and do not present a hazard to the ozone layer. The information obtained in the Phase 1 program indicated that the proposed ESI process is technically effective and economically attractive. The fluorocarbon surfactant solutions used as working media in the ESI process survived exposure of up to 10 Mrad doses of gamma rays, and are considered sufficiently radiation resistant for the proposed process. Ultrasonic cleaning in perfluorinated surfactant solutions was found to be an effective method of removing radioactive iron (Fe 59) oxide particles from contaminated test pieces. Radioactive particles suspended in the process liquids could be quantitatively removed by filtration through a 0.1 um membrane filter. Projected economics indicate a pre-tax pay back time of 1 month for a commercial scale system.

  2. Newtonian to non-Newtonian flow transition in lung surfactants

    NASA Astrophysics Data System (ADS)

    Sadoughi, Amir; Hirsa, Amir; Lopez, Juan

    2010-11-01

    The lining of normal lungs is covered by surfactants, because otherwise the surface tension of the aqueous layer would be too large to allow breathing. A lack of functioning surfactants can lead to respiratory distress syndrome, a potentially fatal condition in both premature infants and adults, and a major cause of death in the US and world-wide. We use a home-built Brewster angle microscope on an optically accessible deep channel viscometer to simultaneously observe the mesoscale structures of DPPC, the primary constituent of lung surfactant, on water surface and measure the interfacial velocity field. The measured interfacial velocity is compared to Navier-Stokes computations with the Boussinesq-Scriven surface model. Results show that DPPC monolayer behaves i) purely elastically at low surface pressures on water, ii) viscoelastically at modest surface pressures, exhibiting non-zero surface shear viscosity that is independent of the shear rate and flow inertia, and iii) at surface pressures approaching film collapse, DPPC loses its fluid characteristics, and a Newtonian surface model no longer captures its hydrodynamics.

  3. Studies of nonequilibrium behavior in surfactant systems using videomicroscopy and diffusion path analysis

    SciTech Connect

    Raney, K.H.

    1986-01-01

    A petroleum sulfonate system typical of those used in surfactant flooding of oil reservoirs was examined to determine salinity effects on nonequilibrium phenomena. Microemulsions and/or brine phases formed as intermediate layers at all salinities. Diffusion paths calculated for a model system match the experimental results with regard to the number and rate of formation of the intermediate phases. Contacting experiments were performed between an oil phase containing oleic acid and caustic brine solutions of varying salinity and pH. Interfacial turbulence and liquid crystal formation were commonplace. Spontaneous emulsification of water in the oil was observed when the surfactant was oil-soluble. Oil-in-water emulsions formed spontaneously when the surfactant was hydrophilic. Hydrocarbons were contacted with aqueous solutions of pure ethyoxylated alcohol surfactants. Enhanced solubilization of oil was seen at temperatures above the cloud point of the nonionic surfactant solutions. Intermediate liquid crystal and microemulsion layers typically formed near the phase inversion temperature, while conversion of oil into a water-in-oil microemulsions occurred at higher temperatures. Comparison of a pure ethoxylated alcohol system was also made to formulations having the same cloud point but containing a different ethoxylated alcohol and a lipophilic additive. Differences in nonequilibrium behavior were observed upon contacting with hydrocarbons due to partitioning of additive into the oleic phase. Finally, contacting experiments were compared to calculated diffusion paths for a well-characterized oil-water-alcohol system. One observation was the formation of an interface across a three-phase region.

  4. Improvement of the growth of InxGa1 - xAs on GaAs (001) using Te as surfactant

    NASA Astrophysics Data System (ADS)

    Grandjean, N.; Massies, J.; Delamarre, C.; Wang, L. P.; Dubon, A.; Laval, J. Y.

    1993-07-01

    It is demonstrated by using reflection high-energy electron diffraction and transmission electron microscopy that the epitaxial growth of highly strained InxGa1-xAs (x≳0.3) layers on GaAs(001) is improved by a preadsorbed Te surfactant layer. The formation of 3D islands is inhibited by the surfactant action and consequently the onset of plastic relaxation (i.e., the critical thickness) is significantly delayed.

  5. Hemolysis by surfactants--A review.

    PubMed

    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.

  6. Adsorption of surfactants on mineral oxide surfaces from aqueous solutions. Part 1. Isomerically pure anionic surfactants

    SciTech Connect

    Scamehorn, J.F.; Schechter, R.S.; Wade, W.H.

    1982-02-01

    The adsorption of surfactants on minerals is detrimental to surfactant-enhanced oil recovery. To minimize adsorption, the forces tending to cause it must be understood. This requires the study of relatively simple, well-defined systems. The majority of surfactant adsorption studies on mineral oxides has been made with surfactant mixtures and not with monoisomerically pure species. Some of the observed results may be due to complex surfactant intercomponent interactions. In this study, the adsorption of 3 isomerically pure alkylbenzene sulfonates was measured on alumina and kaolinite from very low concentrations to well above the critical micelle concentration and a thermodynamic model was developed, which describes the observed isotherms. 59 references.

  7. Modeling and simulations of carbon nanotube (CNT) dispersion in water/surfactant/polymer systems

    NASA Astrophysics Data System (ADS)

    Uddin, Nasir Mohammad

    concentrations and structures on CNT interactions in water were investigated at room conditions. CNT interactions in polymer solution were also investigated with polyethylene oxide (PEO) polymer and water as a solvent. In all cases, the atomic arrangement of molecules was discussed in detailed. Simulations revealed that CNT orientation, length, diameter, and addition of surfactant and its structures can significantly affect CNT interactions (i.e., PMFs varied significantly) and in-turn the degree of CNT dispersion in aqueous solution. For all simulation cases, a uniform sampling was achieved by using the ABF method to calculate the governing PMF between CNTs indicating the effectiveness and convergence of the adaptive sampling scheme. The surfactant molecules were shown to adsorb at the CNT surface and contribute to weaker interactions between CNTs which resulted less CNT aggregate size at the mesoscale. Surfactant consisting with a benzene ring contributed much weaker interactions between CNTs as compared with that of without benzene ring. The increase in CNT length contributed the stronger CNT interactions where the increase in CNT diameter caused weaker CNT interactions in water. The interfacial characteristics between the CNT, surfactant and the polymer were also predicted and discussed. The model can be expanded for more solvents, surfactants, and polymers.

  8. Surfactant-Associated Bacteria in the Sea Surface Microlayer and their Effect on Remote Sensing Technology

    NASA Astrophysics Data System (ADS)

    Kurata, N.; Vella, K.; Tartar, A.; Matt, S.; Shivji, M.; Perrie, W. A.; Soloviev, A.

    2012-12-01

    Synthetic aperture radar remote sensing captures various fine-scale features on the ocean surface such as coastal discharges, oil pollution, vessel traffic, algal blooms and sea slicks. Although numerous factors potentially affect the synthetic aperture radar imaging process, the influence of biogenic and anthropogenic surfactants has been suggested as one of the primary parameters, especially under relatively low wind conditions. Surfactants have a tendency to dampen the short gravity-capillary ocean waves causing the sea surface to smoothen, thus allowing the radar to detect areas of surfactants. Surfactants are found in sea slicks, which are the accumulation of organic material shaped as elongated bands on the ocean's surface. Sea slicks are often observable with the naked eye due to their glassy appearance and can also be seen on synthetic aperture radar images as dark scars. While the sources of surfactants can vary, some are known to be of marine bacteria origin. Countless numbers of marine bacteria are present in the oceanic environment, and their biogeochemical contributions cannot be overlooked. Not only does marine-bacteria produce surfactants, but they also play an important role in the transformation of surfactants. In this study, we profiled the surfactant-associated bacteria composition within the biogenic thin layer of the ocean surface more commonly referred as the sea surface microlayer. Bacterial samples were collected from the sea surface microlayer for comparative analysis from both within and outside of sea slick areas as well as the underlying subsurface water. The bacterial microlayer sampling coincided with synthetic aperture radar satellite, RADARSAT-2, overpasses to demonstrate the simultaneous in-situ measurements during a satellite image capture. The sea surface microlayer sampling method was designed to enable aseptic bacterial sampling. A 47 mm polycarbonate membrane was utilized at each sampling site to obtain a snapshot of the

  9. Selective retardation of perfume oil evaporation from oil-in-water emulsions stabilized by either surfactant or nanoparticles.

    PubMed

    Binks, Bernard P; Fletcher, Paul D I; Holt, Benjamin L; Beaussoubre, Pascal; Wong, Kenneth

    2010-12-01

    We have used dynamic headspace analysis to investigate the evaporation rates of perfume oils from stirred oil-in-water emulsions into a flowing gas stream. We compare the behavior of an oil of low water solubility (limonene) and one of high water solubility (benzyl acetate). It is shown how the evaporation of an oil of low water solubility is selectively retarded and how the retardation effect depends on the oil volume fraction in the emulsion. We compare how the evaporation retardation depends on the nature of the adsorbed film stabilizing the emulsion. Surfactant films are less effective than adsorbed films of nanoparticles, and the retardation can be further enhanced by compression of the adsorbed nanoparticle films by preshrinking the emulsion drops.

  10. Effect of colloidal particle size on adsorbed monodisperse and bidisperse monolayers.

    PubMed

    Rosenberg, Rachel T; Dan, Nily

    2011-07-19

    Coating hydrogel films or microspheres by an adsorbed colloidal shell is one synthesis method for forming colloidosomes. The colloidal shell allows control of the release rate of encapsulated materials, as well as selective transport. Previous studies found that the packing density of self-assembled, adsorbed colloidal monolayers is independent of the colloidal particle size. In this paper we develop an equilibrium model that correlates the packing density of charged colloidal particles in an adsorbed shell to the particle dimensions in monodisperse and bidisperse systems. In systems where the molar concentration in solution is fixed, the increase in adsorption energy with increasing particle size leads to a monotonic increase in the monolayer packing density with particle radius. However, in systems where the mass fraction of the particles in the adsorbing solutions is fixed, increasing particle size also reduces the molar concentration of particles in solution, thereby reducing the probability of adsorption. The result is a nonmonotonic dependence of the packing density in the adsorbed layer on the particle radius. In bidisperse monolayers composed of two particle sizes, the packing density in the layer increases significantly with size asymmetry. These results may be utilized to design the properties of colloidal shells and coatings to achieve specific properties such as transport rate and selectivity.

  11. Pulmonary surfactant protein A (SP-A) specifically binds dipalmitoylphosphatidylcholine

    SciTech Connect

    Kuroki, Y.; Akino, T. )

    1991-02-15

    Phospholipids are the major components of pulmonary surfactant. Dipalmitoylphosphatidylcholine is believed to be especially essential for the surfactant function of reducing the surface tension at the air-liquid interface. Surfactant protein A (SP-A) with a reduced denatured molecular mass of 26-38 kDa, characterized by a collagen-like structure and N-linked glycosylation, interacts strongly with a mixture of surfactant-like phospholipids. In the present study the direct binding of SP-A to phospholipids on a thin layer chromatogram was visualized using 125I-SP-A as a probe, so that the phospholipid specificities of SP-A binding and the structural requirements of SP-A and phospholipids for the binding could be examined. Although 125I-SP-A bound phosphatidylcholine and sphingomyeline, it was especially strong in binding dipalmitoylphosphatidylcholine, but failed to bind phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, and phosphatidylserine. Labeled SP-A also exhibited strong binding to distearoylphosphatidylcholine, but weak binding to dimyristoyl-, 1-palmitoyl-2-linoleoyl-, and dilinoleoylphosphatidylcholine. Unlabeled SP-A readily competed with labeled SP-A for phospholipid binding. SP-A strongly bound dipalmitoylglycerol produced by phospholipase C treatment of dipalmitoylphosphatidylcholine, but not palmitic acid. This protein also failed to bind lysophosphatidylcholine produced by phospholipase A2 treatment of dipalmitoylphosphatidylcholine. 125I-SP-A shows almost no binding to dipalmitoylphosphatidylglycerol and dipalmitoylphosphatidylethanolamine. The addition of 10 mM EGTA into the binding buffer reduced much of the 125I-SP-A binding to phospholipids. Excess deglycosylated SP-A competed with labeled SP-A for binding to dipalmitoylphosphatidylcholine, but the excess collagenase-resistant fragment of SP-A failed.

  12. SURFACTANT SPRAY: A NOVEL TECHNOLOGY TO IMPROVE FLOTATION DEINKING PERFORMANCE

    SciTech Connect

    Yulin Deng; Junyong Zhu

    2004-01-31

    Based on the fundamental understanding of ink removal and fiber loss mechanism in flotation deinking process, we developed this innovative technology using surfactant spray to improve the ink removal efficiency, reduce the water and fiber loss, reduce the chemical consumption and carry over in the flotation deinking. The innovative flotation deinking process uses a spray to deliver the frothing agent during flotation deinking to control several key process variables. The spray can control the foam stability and structure and modify the fluid dynamics to reduce the fibers entrapped in the froth layer. The froth formed at the top part of the flotation column will act as a physical filter to prevent the penetration of frothing agent into the pulp suspension to eliminate fiber contamination and unfavorable deinking surface chemistry modification due to surfactant adsorption on the fiber surface. Because of the filter effect, frothing agents will be better utilized. Under the sponsorships of the US Dept. of Energy (DOE) and the member companies of the Institute of Paper Science and Technology, we studied the chem-mechanical mechanism of surfactant spray for flotation deinking using different furnishes, chemicals, and flotation devices in the past four years. In the final year of the project, we successfully conducted mill trials at Abitibi-Consolidated, Inc., Snowflake paper recycling operation of 100% mixture of ONP/OMG. Results from laboratory, pilot-plant and mill trials indicated that surfactant spray technology can significantly reduce fiber loss in flotation deinking. It can be concluded that paper industry can profit greatly when this technology is commercialized in flotation deinking mills.

  13. Thermodynamic model for surfactant adsorption: Topical report. [Decyltrimethylammonium bromide

    SciTech Connect

    Woodbury, G.W. Jr.; Noll, L.A.

    1987-01-01

    A simple, semi-empirical thermodynamic model was constructed for the adsorption of solutions of surfactants onto solid surfaces. Essentially a modified finite-layer BET theory, the model is complete in that it predicts all surface thermodynamic properties. The properties of bulk solutions are considered in an exact way, and the availability of bulk thermodynamic properties is assumed. The theory has been applied satisfactorily to both the adsorption isotherm and the heat of adsorption curve for the adsorption of decyltrimethylammonium bromide (DTAB) on silica gel. In this system, the observed adsorption which occurs above the critical micelle concentration (CMC) depends on the detailed behavior of the bulk thermodynamic properties; since the measured surface properties are sensitive to bulk properties, the latter must be accounted for accurately. DTAB is the only reported surfactant system, for which both the isotherm and the heat have been measured and for which the bulk solution properties are known. A critical test of the theory awaits more data of this type; however, the theory has been tested against isotherms measured by Scamehorn, et al., and has been found to fit within experimental error below the CMC. There are many areas in which the adsorption of surfactants is of practical importance such as minerals processing, lubrication, and enhanced oil recovery. The theory should prove useful to all of these areas. In the scope of enhanced oil recovery, this theory is intended to be developed into an adsorption module for a reservoir simulator for surfactant-mineral systems whose behavior is too complex to be modeled by Henry's law or even a Langmuir isotherm. 15 refs., 6 figs., 2 tabs.

  14. Alterations in surfactant protein A after acute exposure to ozone.

    PubMed

    Su, W Y; Gordon, T

    1996-05-01

    The surfactant layer covering the gas-exchange region of the lung serves as the initial site of interaction with inhaled oxidant gases. Among the endogenous compounds potentially vulnerable to oxidative injury are surfactant proteins. This study focused on the effect of ozone on surfactant protein A (SP-A) function, content, and gene expression. To determine the time course of response to ozone, guinea pigs were exposed to 0.2-0.8 parts/million (ppm) ozone for 6 h and were killed up to 120 h postexposure. To determine the effect of repeated exposure, animals were exposed to 0.8 ppm ozone for 6 h/day and were killed on days 3 and 5. A significant increase in surfactant's ability to modulate the respiratory burst induced by phorbol 12-myristate 13-acetate in naive macrophages was observed at 24 h after a single 0.8 ppm ozone exposure. Because neutralizing antibodies to SP-A blunted this stimulatory effect, we hypothesized that ozone enhanced the modulatory role of SP-A in macrophage function. This alteration in function was accompanied by an influx of inflammatory cells and only marginal changes in SP-A levels as determined by an enzyme-linked immunosorbent assay. No significant changes in steady-state levels of SP-A mRNA were observed after single or repeated exposure to ozone. Thus the inflammation that accompanies in vivo ozone exposure may result in a change in the structure and thus functional role of SP-A in modulating macrophage activity.

  15. Surfactant and pulmonary blood flow distributions following treatment of premature lambs with natural surfactant.

    PubMed Central

    Jobe, A; Ikegami, M; Jacobs, H; Jones, S

    1984-01-01

    Prematurely delivered lambs were treated with radiolabeled natural surfactant by either tracheal instillation at birth and before the onset of mechanical ventilation, or after 23 +/- 1 (+/- SE) min of mechanical ventilation. Right ventricular blood flow distributions, left ventricular outputs, and left-to-right ductal shunts were measured with radiolabeled microspheres. After sacrifice, the lungs of lambs receiving surfactant at birth inflated uniformly with constant distending pressure while the lungs of lambs treated after a period of ventilation had aerated, partially aerated, and atelectatic areas. All lungs were divided into pieces which were weighed and catalogued as to location. The amount of radiolabeled surfactant and microsphere-associated radioactivity in each piece of lung was quantified. Surfactant was relatively homogenously distributed to pieces of lung from lambs that were treated with surfactant at birth; 48% of lung pieces received amounts of surfactant within +/- 25% of the mean value. Surfactant was preferentially recovered from the aerated pieces of lungs of lambs treated after a period of mechanical ventilation, and the distribution of surfactant to these lungs was very nonhomogeneous. Right ventricular blood flow distributions to the lungs were quite homogeneous in both groups of lambs. However, in 8 of 12 lambs, pulmonary blood flow was preferentially directed away from those pieces of lung that received relatively large amounts of surfactant and toward pieces of lung that received less surfactant. This acute redirection of pulmonary blood flow distribution may result from the local changes in compliances within the lung following surfactant instillation. PMID:6546766

  16. Innovation in surfactant therapy I: surfactant lavage and surfactant administration by fluid bolus using minimally invasive techniques.

    PubMed

    Dargaville, Peter A

    2012-01-01

    Innovation in the field of exogenous surfactant therapy continues more than two decades after the drug became commercially available. One such innovation, lung lavage using dilute surfactant, has been investigated in both laboratory and clinical settings as a treatment for meconium aspiration syndrome (MAS). Studies in animal models of MAS have affirmed that dilute surfactant lavage can remove meconium from the lung, with resultant improvement in lung function. In human infants both non-randomised studies and two randomised controlled trials have demonstrated a potential benefit of dilute surfactant lavage over standard care. The largest clinical trial, performed by our research group in infants with severe MAS, found that lung lavage using two 15-ml/kg aliquots of dilute surfactant did not reduce the duration of respiratory support, but did appear to reduce the composite outcome of death or need for extracorporeal membrane oxygenation. A further trial of lavage therapy is planned to more precisely define the effect on survival. Innovative approaches to surfactant therapy have also extended to the preterm infant, for whom the more widespread use of continuous positive airway pressure (CPAP) has meant delaying or avoiding administration of surfactant. In an effort to circumvent this problem, less invasive techniques of bolus surfactant therapy have been trialled, including instillation directly into the pharynx, via laryngeal mask and via brief tracheal catheterisation. In a recent clinical trial, instillation of surfactant into the trachea using a flexible feeding tube was found to reduce the need for subsequent intubation. We have developed an alternative method of brief tracheal catheterisation in which surfactant is delivered via a semi-rigid vascular catheter inserted through the vocal cords under direct vision. In studies to date, this technique has been relatively easy to perform, and resulted in rapid improvement in lung function and reduced need for

  17. [Preparation of novel magnetic dextran affinity adsorbents and their application to purify urokinase].

    PubMed

    Dong, Y S; Liang, F; Yu, X Y; Guo, L A; Chang, J H

    2001-01-01

    The reverse phase suspension and embedment technique were adopted to prepare magnetic dextran microsphere (MDMS). The dispersion medium was mixture of some organic solvents. Span-80 was used as stabilizer. The aqueous dextran with magnetic fluid was suspended in dispersion medium with epichlorohydrin as cross-linking reagent. The mixture was stirred for 30 minutes at room temperature and then heated at 70 degrees C for 4 hours, MDMS was thus obtained. MDMS was activated by epichlorohydrin on which 6-aminohexanoic acid, glycine or ethylene diamine was bonded as spacers. Then it was coupled with p-aminobenzamide, L-arginine methyl ester or guanidohexanoic acid and five magnetic affinity adsorbents were prepared. The MDMS was polydisperse particles with the size of 50-300 meshes and the content of Fe3O4 was about 6.2 per cent in the MDMS. Influence of some parameters such as viscosity and density of organic phase, the volume ratio of organic and aqueous phase, the quantity of surfactant and stirring speed on preparing MDMS was studied. Magnetic affinity adsorbents were used to purify crude urokinase in a bath mode and the effect of coupling reagents and ligands on results of purification was discussed. The bioactivity recovery was 40.0 to 60.7 per cent, the purification-fold was between 14.9 and 32.8, and the adsorptive capacity varies from 89 mg to 121 mg per milliliter of adsorbent. PMID:12541840

  18. Insight into the adsorption of PPCPs by porous adsorbents: Effect of the properties of adsorbents and adsorbates.

    PubMed

    Zhu, Zengyin; Xie, Jiawen; Zhang, Mancheng; Zhou, Qing; Liu, Fuqiang

    2016-07-01

    Adsorption is an efficient method for removal of pharmaceuticals and personal care products (PPCPs). Magnetic resins are efficient adsorbents for water treatment and exhibit potential for PPCP removal. In this study, the magnetic hypercrosslinked resin Q100 was used for adsorption of PPCPs. The adsorption behavior of this resin was compared with those of two activated carbons, namely, Norit and F400D. Norit exhibited the fastest adsorption kinetics, followed by Q100. Norit featured a honeycomb shape and long-range ordered pore channels, which facilitated the diffusion of PPCPs. Moreover, the large average pore size of Q100 reduced diffusion resistance. The adsorbed amounts of 11 PPCPs on the three adsorbents increased with increasing adsorbate hydrophobicity. For Q100, a significant linear correlation was observed between the adsorption performance for PPCPs and hydrophobicity (logD value) of adsorbates (R(2) = 0.8951); as such, PPCPs with high logD values (>1.69) could be efficiently removed. Compared with those of Norit and F400D, the adsorption performance of Q100 was less affected by humic acid because of the dominant hydrophobic interaction. Furthermore, Q100 showed improved regeneration performance, which renders it promising for PPCP removal in practical applications. PMID:27131811

  19. Cosurfactant in preflush for surfactant flood system

    SciTech Connect

    Glinsmann, G.R.; Hedges, J.H.

    1981-06-23

    In a post-primary oil recovery process involving the sequential addition of a saline preflush, a surfactant system comprising of a surfactant, a cosurfactant and brine when added to the preflush improves recovery. If desired, cosurfactant can also be added to a subsequent injected mobility buffer. The resulting system gives extraordinarily high recovery of oil.

  20. Hyaluronan decreases surfactant inactivation in vitro.

    PubMed

    Lu, Karen W; Goerke, Jon; Clements, John A; Taeusch, H William

    2005-02-01

    Hyaluronan (HA) is an anionic polymer and a constituent of alveolar fluid that can bind proteins, phospholipids, and water. Previous studies have established that nonionic polymers improve the surface activity of pulmonary surfactants by decreasing inactivation of surfactant. In this work, we investigate whether HA can also have beneficial effects when added to surfactants. We used a modified pulsating bubble surfactometer to measure mixtures of several commercially available pulmonary surfactants or native calf surfactant with and without serum inactivation. Surface properties such as equilibrium surface tension, minimum and maximum surface tensions on compression and expansion of a surface film, and degree of surface area reduction required to reach a surface tension of 10 mN/m were measured. In the presence of serum, addition of HA dramatically improved the surface activities of all four surfactants and in some cases in the absence of serum as well. These results indicate that HA reduces inactivation of surfactants caused by serum and add evidence that endogenous HAs may interact with alveolar surfactant under normal and abnormal conditions.

  1. Surfactant Adsorption: A Revised Physical Chemistry Lab

    ERIC Educational Resources Information Center

    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…

  2. Measuring surfactant concentration in plating solutions

    DOEpatents

    Bonivert, William D.; Farmer, Joseph C.; Hachman, John T.

    1989-01-01

    An arrangement for measuring the concentration of surfactants in a electrolyte containing metal ions includes applying a DC bias voltage and a modulated voltage to a counter electrode. The phase angle between the modulated voltage and the current response to the modulated voltage at a working electrode is correlated to the surfactant concentration.

  3. Kinetics of spreading of surfactant solutions

    NASA Astrophysics Data System (ADS)

    Starov, Victor; Kovalchuk, Nina; Trybala, Anna; Matar, Omar

    2014-11-01

    Wetting properties of surfactant solutions are determined by adsorption of surfactant at all interfaces involved. Adsorption on liquid/air and liquid/solid interface depends on surfactant chemistry. That is why the lower surface tension does not result automatically in better wetting properties. Spreading of surfactant solutions causes redistribution of surfactant at the interface and in the bulk. As a result surface concentration gradients appear and spreading kinetics is influenced by solutal Marangoni effect. Disjoining pressure, being the driving force of spreading also depends on the local surfactant concentration. Therefore spreading kinetics of surfactant solutions differ considerably from those of pure liquids. The results of experimental study on spreading kinetics of synergetic surfactant mixtures on hydrophobic substrates such as polyethylene and sylanised glass are presented for the two different regimes: complete and partial wetting and compared with the spreading kinetics of a pure liquid in those regimes. EPSRC Grant Numbers EP/J010502/1, EP/D077869/1, EU Marie Curie CoWet Grant, by ESA under Grants FASES and PASTA, and COST MP1106 Project.

  4. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-07-01

    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. We have conducted adsorption, phase behavior, interfacial tension (IFT) and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases IFT with a minimum at about 0.2 M. Addition of surfactant decreases IFT further. In the absence of surfactant the minerals are oil-wet after aging with crude oil. Addition of surfactant solution decreases the contact angle to intermediate-wet for many surfactants and water-wet for one surfactant. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Plans for the next quarter include conducting core adsorption, phase behavior, wettability and mobilization studies.

  5. Oil recovery by fluorochemical surfactant waterflooding

    SciTech Connect

    Cooke, T.W.

    1984-07-17

    The instant invention relates to the recovery of oil from subterranean oil reservoirs involving the injection of an aqueous based liquid containing a fluorochemical surfactant possessing an oleophobic-hydrophobic fluoroaliphatic group, a hydrophilic group and an oleophilic group, optionally in conjugation with a conventional enhanced oil recovery surfactant.

  6. Interaction of Surfactants with Block Polyelectrolyte Gels

    NASA Astrophysics Data System (ADS)

    Crichton, Mark; Bhatia, Surita

    2002-03-01

    We present SANS and rheology for poly(styrene)-poly(acrylic acid) polymers in aqueous solutions. These polymers self-assemble to form spherical micelles in aqueous solutions, and the micelles associate to create elastic, transparent gels at moderate polymer concentrations. The addition of cationic and anionic surfactants (DTAB and SDS) can be used to modify the associative interactions and solution rheology. Addition of an anionic surfactant acts to screen attractive interactions and causes a monotonic decrease in the elastic modulus. However, the addition of a cationic surfactant appears to initially induce a stronger intermicellar attraction, leading to gels with a higher elastic modulus. At higher surfactant concentrations, the cationic surfactant begins to screen intermicellar association, leading to a decrease in the strength of the gel.

  7. Surfactant screening of diesel-contaminated soil

    SciTech Connect

    Peters, R.W.; Montemagno, C.D.; Shem, L. ); Lewis, B.A. . Dept. of Civil Engineering)

    1990-01-01

    At one installation, approximately 60,000 gal of No. 2 diesel fuel leaked into the subsurface environment, with contamination at depths of 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. The treatability studies focused on four separate phases: (1) leachability studies on the various contaminated soil borings, (2) air stripping studies, (3) bioremediation studies, and (4) surfactant screening/surfactant flooding studies. This paper summarizes the fourth phase of the research program in which twenty-one surfactants were screened for possible use to mobilize the organics from the contaminated soil prior to bioremediation. Anionic surfactants resulted in the greatest degree of diesel mobilization. The most promising surfactants will be employed on actual contaminated soil samples obtained from the site. 18 refs., 16 figs., 1 tab.

  8. Negative chromatography of hepatitis B virus-like particle: Comparative study of different adsorbent designs.

    PubMed

    Lee, Micky Fu Xiang; Chan, Eng Seng; Tan, Wen Siang; Tam, Kam Chiu; Tey, Beng Ti

    2016-05-01

    Purification of virus-like particles (VLPs) in bind-and-elute mode has reached a bottleneck. Negative chromatography has emerged as the alternative solution; however, benchmark of negative chromatography media and their respective optimized conditions are absent. Hence, this study was carried out to compare the performance of different negative chromatography media for the purification of hepatitis B VLPs (HB-VLPs) from clarified Escherichia coli feedstock. The modified anion exchange media, core-shell adsorbents (InertShell and InertLayer 1000) and polymer grafted adsorbents (SQ) were compared. The results of chromatography from packed bed column of core-shell adsorbents showed that there is a trade-off between the purity and recovery of HB-VLPs in the flowthrough fraction due to the shell thickness. Atomic force microscopic analysis revealed funnel-shaped pore channels in the shell layer which may contribute to the entrapment of HB-VLPs. A longer residence time at a lower feed flow rate (0.5ml/min) improved slightly the HB-VLPs purity in all modified adsorbents, but the recovery in InertShell reduced substantially. The preheat-treatment is not recommended for the negative chromatography as the thermal-induced co-aggregation of HCPs and HB-VLPs would flow along with HB-VLPs and thus reduced the HB-VLPs purity in the flowthrough. Further reduction in the feedstock concentration enhanced the purity of HB-VLPs especially in InertLayer 1000 but reduced substantially the recovery of HB-VLPs. In general, the polymer grafted adsorbent, SQ, performed better than the core-shell adsorbents in handling a higher feedstock concentration.

  9. Negative chromatography of hepatitis B virus-like particle: Comparative study of different adsorbent designs.

    PubMed

    Lee, Micky Fu Xiang; Chan, Eng Seng; Tan, Wen Siang; Tam, Kam Chiu; Tey, Beng Ti

    2016-05-01

    Purification of virus-like particles (VLPs) in bind-and-elute mode has reached a bottleneck. Negative chromatography has emerged as the alternative solution; however, benchmark of negative chromatography media and their respective optimized conditions are absent. Hence, this study was carried out to compare the performance of different negative chromatography media for the purification of hepatitis B VLPs (HB-VLPs) from clarified Escherichia coli feedstock. The modified anion exchange media, core-shell adsorbents (InertShell and InertLayer 1000) and polymer grafted adsorbents (SQ) were compared. The results of chromatography from packed bed column of core-shell adsorbents showed that there is a trade-off between the purity and recovery of HB-VLPs in the flowthrough fraction due to the shell thickness. Atomic force microscopic analysis revealed funnel-shaped pore channels in the shell layer which may contribute to the entrapment of HB-VLPs. A longer residence time at a lower feed flow rate (0.5ml/min) improved slightly the HB-VLPs purity in all modified adsorbents, but the recovery in InertShell reduced substantially. The preheat-treatment is not recommended for the negative chromatography as the thermal-induced co-aggregation of HCPs and HB-VLPs would flow along with HB-VLPs and thus reduced the HB-VLPs purity in the flowthrough. Further reduction in the feedstock concentration enhanced the purity of HB-VLPs especially in InertLayer 1000 but reduced substantially the recovery of HB-VLPs. In general, the polymer grafted adsorbent, SQ, performed better than the core-shell adsorbents in handling a higher feedstock concentration. PMID:27059397

  10. Influence of a nonionic surfactant (Triton X-100) on contaminant distribution between water and several soil solids

    USGS Publications Warehouse

    Lee, J.-F.; Liao, P.-M.; Kuo, C.-C.; Yang, H.-T.; Chiou, C.T.

    2000-01-01

    The influence of a nonionic surfactant (Triton X-100) on the contaminant distribution coefficients in solid-water mixtures was determined for a number of relatively nonpolar compounds (contaminants) on several natural solids. The studied compounds consisted of BTEX (benzene, toluene, ethylbenzene, and p-xylene) and chlorinated pesticides (lindane, ??-BHC, and heptachlor epoxide), which span several orders of magnitude in water solubility (S(W)); the solid samples comprised a bentonite, a peat, and two other soils, which cover a wide range of solid organic matter (SOM) content. The applied surfactant concentrations (X) ranged from below the (nominal) CMC to 2-3 times the CMC. For relatively water-soluble BTEX compounds, the distribution coefficients with surfactant (K*(d)) all exceeded those without surfactant (K(d)); the K*(d)/K(d) ratios increased with increasing S(w) from p-xylene to benzene on each solid at a given X, with increasing X for each compound on a solid, and with decreasing solid SOM content for each compound over the range of X studied. For the less-soluble pesticides, the K*(d)/K(d) ratios exhibited a large increase with X for bentonite, a marginal change (increase or decrease) for a soil of 2.4% SOM, and a moderate-to-large decrease for two soils of 14.8% and 86.4% SOM. These unique observations were rationalized in terms of the properties of the compound, the amount of surfactant sorbed on the solid, the enhanced solubilization of the compound by surfactant in water, and the relative effects of the surfactant when adsorbed on minerals and when partitioned into SOM. (C) 2000 Academic Press.

  11. Fibrinogen stability under surfactant interaction.

    PubMed

    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.

  12. Size selective hydrophobic adsorbent for organic molecules

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor); Hickey, Gregory S. (Inventor)

    1997-01-01

    The present invention relates to an adsorbent formed by the pyrolysis of a hydrophobic silica with a pore size greater than 5 .ANG., such as SILICALITE.TM., with a molecular sieving polymer precursor such as polyfurfuryl alcohol, polyacrylonitrile, polyvinylidene chloride, phenol-formaldehyde resin, polyvinylidene difluoride and mixtures thereof. Polyfurfuryl alcohol is the most preferred. The adsorbent produced by the pyrolysis has a silicon to carbon mole ratio of between about 10:1 and 1:3, and preferably about 2:1 to 1:2, most preferably 1:1. The pyrolysis is performed as a ramped temperature program between about 100.degree. and 800.degree. C., and preferably between about 100.degree. and 600.degree. C. The present invention also relates to a method for selectively adsorbing organic molecules having a molecular size (mean molecular diameter) of between about 3 and 6 .ANG. comprising contacting a vapor containing the small organic molecules to be adsorbed with the adsorbent composition of the present invention.

  13. Black Molecular Adsorber Coatings for Spaceflight Applications

    NASA Technical Reports Server (NTRS)

    Abraham, Nithin Susan; Hasegawa, Mark Makoto; Straka, Sharon A.

    2014-01-01

    The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

  14. Black molecular adsorber coatings for spaceflight applications

    NASA Astrophysics Data System (ADS)

    Abraham, Nithin S.; Hasegawa, Mark M.; Straka, Sharon A.

    2014-09-01

    The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

  15. Interlocking order parameter fluctuations in structural transitions between adsorbed polymer phases.

    PubMed

    Martins, Paulo H L; Bachmann, Michael

    2016-01-21

    By means of contact-density chain-growth simulations of a simple coarse-grained lattice model for a polymer grafted at a solid homogeneous substrate, we investigate the complementary behavior of the numbers of surface-monomer and monomer-monomer contacts under various solvent and thermal conditions. This pair of contact numbers represents an appropriate set of order parameters that enables the distinct discrimination of significantly different compact phases of polymer adsorption. Depending on the transition scenario, these order parameters can interlock in perfect cooperation. The analysis helps understand the transitions from compact filmlike adsorbed polymer conformations into layered morphologies and dissolved adsorbed structures, respectively, in more detail.

  16. Method for modifying trigger level for adsorber regeneration

    DOEpatents

    Ruth, Michael J.; Cunningham, Michael J.

    2010-05-25

    A method for modifying a NO.sub.x adsorber regeneration triggering variable. Engine operating conditions are monitored until the regeneration triggering variable is met. The adsorber is regenerated and the adsorbtion efficiency of the adsorber is subsequently determined. The regeneration triggering variable is modified to correspond with the decline in adsorber efficiency. The adsorber efficiency may be determined using an empirically predetermined set of values or by using a pair of oxygen sensors to determine the oxygen response delay across the sensors.

  17. Surfactant replacement therapy--economic impact.

    PubMed

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

    2001-06-01

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

  18. Different effects of surfactant proteins B and C - implications for development of synthetic surfactants.

    PubMed

    Curstedt, Tore; Johansson, Jan

    2010-06-01

    Treatment of premature newborn rabbits with synthetic surfactants containing a surfactant protein C analogue in a simple phospholipid mixture gives similar tidal volumes as treatment with poractant alfa (Curosurf(R)) but ventilation with a positive end-expiratory pressure (PEEP) is needed for this synthetic surfactant to stabilize the alveoli at end-expiration. The effect on lung gas volumes seems to depend on the structure of the peptide since treatment with a synthetic surfactant containing the 21-residue peptide (LysLeu(4))(4)Lys (KL(4)) gives low lung gas volumes in experiments also performed with PEEP. Surfactant preparations containing both surfactant proteins B and C or their analogues prevent alveolar collapse at end-expiration even if ventilated without PEEP. Treatment of premature newborn rabbits with different natural surfactants indicates that both the lipid composition and the proteins are important in order to stabilize the alveoli at end-expiration. Synthetic surfactants containing two peptides may be able to replace natural surfactants within the near future but more trials need to be performed before any conclusion can be drawn about the ideal composition of this new generation of synthetic surfactants.

  19. Natural oil nanoemulsions as cores for layer-by-layer encapsulation.

    PubMed

    Adamczak, M; Para, G; Simon, C; Warszyński, P

    2013-01-01

    In this study, emulsions of three different natural oils were prepared using spontaneous emulsification technique. The effect of three emulsifiers, AOT, lecithin and cholesterol on emulsion properties was studied. Their influence on interfacial tension at oil/water interface was evaluated by the pendant drop shape analysis method. Then, the mean droplet size, zeta potential and stability of emulsions were investigated in relation with the type of oil, surfactant, oil-to-ethanol ratio and surfactant concentration. We found that in the case of linseed oil, fine emulsion droplets are formed without any surfactant due to its low oil/water interfacial tension. A hydrophobic dye (Coumarin 6) was encapsulated within oil cores and its presence was confirmed by fluorescence spectroscopy and microscopy. The obtained emulsions can be used alone or as the cores for layer-by-layer encapsulation, which was demonstrated by enclosing droplets within first layer of synthetic polycation poly(allyamine hydrochloride) (PAH). PMID:23489013

  20. Natural oil nanoemulsions as cores for layer-by-layer encapsulation.

    PubMed

    Adamczak, M; Para, G; Simon, C; Warszyński, P

    2013-01-01

    In this study, emulsions of three different natural oils were prepared using spontaneous emulsification technique. The effect of three emulsifiers, AOT, lecithin and cholesterol on emulsion properties was studied. Their influence on interfacial tension at oil/water interface was evaluated by the pendant drop shape analysis method. Then, the mean droplet size, zeta potential and stability of emulsions were investigated in relation with the type of oil, surfactant, oil-to-ethanol ratio and surfactant concentration. We found that in the case of linseed oil, fine emulsion droplets are formed without any surfactant due to its low oil/water interfacial tension. A hydrophobic dye (Coumarin 6) was encapsulated within oil cores and its presence was confirmed by fluorescence spectroscopy and microscopy. The obtained emulsions can be used alone or as the cores for layer-by-layer encapsulation, which was demonstrated by enclosing droplets within first layer of synthetic polycation poly(allyamine hydrochloride) (PAH).

  1. Untangleing the effects of chain rigidity on the structure and dynamics of strongly adsorbed polymer melts

    SciTech Connect

    Carrillo, Jan-Michael Y.; Cheng, Shiwang; Kumar, Rajeev; Goswami, Monojoy; Sokolov, Alexei P; Sumpter, Bobby G.

    2015-06-11

    Here, we present a detailed analysis of coarse-grained molecular dynamics simulations of semiflexible polymer melts in contact with a strongly adsorbing substrate. We have characterized the segments in the interfacial layer by counting the number of trains, loops, tails and unadsorbed segments. For more rigid chains, a tail and an adsorbed segment (a train) dominate while loops are more prevalent in more flexible chains. The tails exhibit a non-uniformly stretched conformation akin to the polydispersed pseudobrush envisioned by Guiselin. To probe the dynamics of the segments we computed the layer z-resolved intermediate coherent collective dynamics structure factor, S(q, t, z), mean-square displacement of segments, and the 2nd Legendre polynomial of the time-autocorrelation of unit bond vectors, 2[ni(t,z)•ni(0,z)]>. Our results show that segmental dynamics is slower for stiffer chains and there is a strong correlation between the structure and dynamics in the interfacial layer. There is no glassy layer, and the slowing down in dynamics of stiffer chains in the adsorbed region can be attributed to the densification and the more persistent layering of segments.

  2. Untangleing the effects of chain rigidity on the structure and dynamics of strongly adsorbed polymer melts

    DOE PAGES

    Carrillo, Jan-Michael Y.; Cheng, Shiwang; Kumar, Rajeev; Goswami, Monojoy; Sokolov, Alexei P; Sumpter, Bobby G.

    2015-06-11

    Here, we present a detailed analysis of coarse-grained molecular dynamics simulations of semiflexible polymer melts in contact with a strongly adsorbing substrate. We have characterized the segments in the interfacial layer by counting the number of trains, loops, tails and unadsorbed segments. For more rigid chains, a tail and an adsorbed segment (a train) dominate while loops are more prevalent in more flexible chains. The tails exhibit a non-uniformly stretched conformation akin to the polydispersed pseudobrush envisioned by Guiselin. To probe the dynamics of the segments we computed the layer z-resolved intermediate coherent collective dynamics structure factor, S(q, t, z),more » mean-square displacement of segments, and the 2nd Legendre polynomial of the time-autocorrelation of unit bond vectors, 2[ni(t,z)•ni(0,z)]>. Our results show that segmental dynamics is slower for stiffer chains and there is a strong correlation between the structure and dynamics in the interfacial layer. There is no glassy layer, and the slowing down in dynamics of stiffer chains in the adsorbed region can be attributed to the densification and the more persistent layering of segments.« less

  3. Room temperature direct band gap emission characteristics of surfactant mediated grown compressively strained Ge films

    NASA Astrophysics Data System (ADS)

    Katiyar, Ajit K.; Grimm, Andreas; Bar, R.; Schmidt, Jan; Wietler, Tobias; Joerg Osten, H.; Ray, Samit K.

    2016-10-01

    Compressively strained Ge films have been grown on relaxed Si0.45Ge0.55 virtual substrates using molecular beam epitaxy in the presence of Sb as a surfactant. Structural characterization has shown that films grown in the presence of surfactant exhibit very smooth surfaces with a relatively higher strain value in comparison to those grown without any surfactant. The variation of strain with increasing Ge layer thickness was analyzed using Raman spectroscopy. The strain is found to be reduced with increasing film thickness due to the onset of island nucleation following Stranski-Krastanov growth mechanism. No phonon assisted direct band gap photoluminescence from compressively strained Ge films grown on relaxed Si0.45Ge0.55 has been achieved up to room temperature. Excitation power and temperature dependent photoluminescence have been studied in details to investigate the origin of different emission sub-bands.

  4. Effect of surfactant and solvent on spin-lattice relaxation dynamics of magnetic nanocrystals.

    PubMed

    Maiti, Sourav; Chen, Hsiang-Yun; Chen, Tai-Yen; Hsia, Chih-Hao; Son, Dong Hee

    2013-04-25

    The effect of varying the surfactant and solvent medium on the dynamics of spin-lattice relaxation in photoexcited Fe3O4 nanocrystals has been investigated by measuring the time-dependent magnetization employing pump-probe transient Faraday rotation technique. The variation of the surfactants having surface-binding functional groups modified not only the static magnetization but also the dynamics of the recovery of the magnetization occurring via spin-lattice relaxation in the photoexcited Fe3O4 nanocrystals. The variation of the polarity and size of the solvent molecules can also influence the spin-lattice relaxation dynamics. However, the effect is limited to the nanocrystals having sufficiently permeable surfactant layer, where the small solvent molecules (e.g., water) can access the surface and dynamically modify the ligand field on the surface. PMID:23003213

  5. DNA compaction by azobenzene-containing surfactant

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

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

  6. DNA compaction by azobenzene-containing surfactant

    SciTech Connect

    Zakrevskyy, Yuriy; Kopyshev, Alexey; Lomadze, Nino; Santer, Svetlana

    2011-08-15

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

  7. Fluorescence emission of pyrene in surfactant solutions.

    PubMed

    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.

  8. Adsorption of dimeric surfactants in lamellar silicates

    NASA Astrophysics Data System (ADS)

    Balcerzak, Mateusz; Pietralik, Zuzanna; Domka, Ludwik; Skrzypczak, Andrzej; Kozak, Maciej

    2015-12-01

    The adsorption of different types of cationic surfactants in lamellar silicates changes their surface character from hydrophilic to hydrophobic. This study was undertaken to obtain lamellar silicates modified by a series of novel dimeric (gemini) surfactants of different length alkyl chains and to characterise these organophilised materials. Synthetic sodium montmorillonite SOMASIF® ME 100 (M) and enriched bentonite of natural origin (Nanoclay - hydrophilic bentonite®) were organophilised with dimeric (gemini) surfactants (1,1‧-(1,4-butanediyl)bis(alkoxymethyl)imidazolium dichlorides). As a result of surfactant molecule adsorption in interlamellar space, the d-spacing (d001) increased from 0.97 nm (for the anhydrous structure) to 2.04 nm. A Fourier transform infrared spectroscopy (FTIR) analysis of the modified systems reveals bands assigned to the stretching vibrations of the CH2 and CH3 groups and the scissoring vibrations of the NH group from the structure of the dimeric surfactants. Thermogravimetric (TG) and derivative thermogravimetric (DTG) studies imply a four-stage process of surfactant decomposition. Scanning electron microscopy (SEM) images provide information on the influence of dimeric surfactant intercalation into the silicate structures. Particles of the modified systems show a tendency toward the formation of irregularly shaped agglomerates.

  9. Aqueous Foam Stabilized by Tricationic Amphiphilic Surfactants

    NASA Astrophysics Data System (ADS)

    Heerschap, Seth; Marafino, John; McKenna, Kristin; Caran, Kevin; Feitosa, Klebert; Kevin Caran's Research Group Collaboration

    2015-03-01

    The unique surface properties of amphiphilic molecules have made them widely used in applications where foaming, emulsifying or coating processes are needed. The development of novel architectures with multi-cephalic/tailed molecules have enhanced their anti-bacterial activity in connection with tail length and the nature of the head group. Here we report on the foamability of two triple head double, tail cationic surfactants (M-1,14,14, M-P, 14,14) and a triple head single tail cationic surfactant (M-1,1,14) and compare them with commercially available single headed, single tailed anionic and cationic surfactants (SDS,CTAB and DTAB). The results show that bubble rupture rate decrease with the length of the carbon chain irrespective of head structure. The growth rate of bubbles with short tailed surfactants (SDS) and longer, single tailed tricationic surfactants (M-1,1,14) was shown to be twice as high as those with longer tailed surfactants (CTAB, M-P,14,14, M-1,14,14). This fact was related to the size variation of bubbles, where the foams made with short tail surfactants exhibited higher polydispersivity than those with short tails. This suggests that foams with tricationic amphiphilics are closed linked to their tail length and generally insensitive to their head structure.

  10. Surfactants tailored by the class Actinobacteria

    PubMed Central

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

    2015-01-01

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

  11. Tunable, antibacterial activity of silicone polyether surfactants.

    PubMed

    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. A study of surfactant-assisted waterflooding

    SciTech Connect

    Scamehorn, J F; Harwell, J H

    1990-09-01

    In surfactant-assisted waterflooding, a surfactant slug is injected into a reservoir, followed by a brine spacer, followed by second surfactant slug. The charge on the surfactant in the first slug has opposite sign to that in the second slug. When the two slugs mix in the reservoir, a precipitate or coacervate is formed which plugs the permeable region of the reservoir. Subsequently injected water or brine is forced through the low permeability region of the reservoir, increasing sweep efficiency of the waterflood, compared to a waterflood not using surfactants. In this part of the work, two major tasks are performed. First, core floods are performed with oil present to demonstrate the improvement in incremental oil production, as well as permeability modification. Second, a reservoir simulation model will be proposed to further delineate the optimum strategy for implementation of the surfactant-assisted waterflooding, as well as indicate the reservoir types for which it would be most effective. Surfactants utilized were sodium dodecyl sulfate and dodecyl pyridinium chloride. 44 refs., 17 figs., 3 tabs.

  13. Tunable, antibacterial activity of silicone polyether surfactants.

    PubMed

    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. PMID:26057244

  14. Self-assembled systems of water soluble metal 8-hydroxyquinolates with surfactants and conjugated polyelectrolytes.

    PubMed

    Burrows, Hugh D; Costa, Telma; Ramos, M Luisa; Valente, Artur J M; Stewart, Beverly; Justino, Licinia L G; Almeida, Aline I A; Catarina, Nathanny Lessa; Mallavia, Ricardo; Knaapila, Matti

    2016-06-22

    We have studied the interaction of 8-hydroxyquinoline-5-sulfonate (8-HQS) with the metal ions Al(iii) and Zn(ii) in aqueous solution in the presence of tetraalkylammonium surfactants using UV/vis absorption, fluorescence, NMR spectroscopy and electrical conductivity measurements, complemented by DFT calculations and molecular dynamics (MD) simulations. Under appropriate conditions, complexes between 8-HQS and metal ions form rapidly, and have similar electronic, spectroscopic and photophysical properties to the corresponding metal quinolates, such as Alq3. These interact with the cationic surfactants, leading to marked increases in fluorescence intensity. However, significant differences are seen in the behavior of the two metal ions. With aluminium, a stable [Al(8-QS)3](3-) anion is formed, and interacts, predominantly through electrostatic interactions, with the surfactant, without disrupting the metal ion coordination sphere. In contrast, with Zn(ii), there is a competition between the metal ion and surfactants in the interaction with 8-HQS, although the [Zn(8-QS)2(H2O)2](2-) species is stable at appropriate pH and surfactant concentration. The studies are extended to systems with the conjugated polyelectrolyte (CPE) poly-(9,9-bis(6-N,N,N-trimethylammonium)hexyl)-fluorene-phenylene bromide (HTMA-PFP), which has a similar alkylammonium chain to the surfactants. Mixing metal salt, 8-HQS and HTMA-PFP in the presence of a nonionic surfactant leads to the formation of a metal complex/CPE supramolecular assembly between the conjugated polyelectrolyte and the metal/8-HQS complex, as demonstrated by electronic energy transfer. The potential of these systems in sensing, light harvesting, and electron injection/transport layers in organic semiconductor devices is discussed. PMID:26817700

  15. Structural precursor to adsorbate-induced reconstruction: C on Ni(100)

    SciTech Connect

    Terborg, R.; Hoeft, J.T.; Polcik, M.; Lindsay, R.; Schaff, O.; Bradshaw, A.M.; Toomes, R.; Booth, N.A.; Woodruff, D.P.; Rotenberg, E.; Denlinger, J.

    1999-10-01

    The local structure around adsorbed carbon atoms on Ni(100) has been determined at low coverage as well as in the 0.5 monolayer (2{times}2)p4g {open_quotes}clock{close_quotes} reconstruction by scanned energy mode photoelectron diffraction. At low coverage, there is no radial strain of the Ni atoms surrounding the adsorbed carbon, contrary to previous suggestions. None of the C-Ni near-neighbor distances are changed by reconstruction, but the Ni-Ni nearest-neighbor distance in the top layer increases significantly, showing that the adsorbate-induced compressive stress is associated with Ni-Ni, rather than Ni-C, repulsion. {copyright} {ital 1999} {ital The American Physical Society}

  16. Novel insights in Al-MCM-41 precursor as adsorbent for regulated haloacetic acids and nitrate from water.

    PubMed

    Bruzzoniti, Maria Concetta; De Carlo, Rosa Maria; Sarzanini, Corrado; Caldarola, Dario; Onida, Barbara

    2012-11-01

    High concentration of NO (3) (-) in groundwater has raised concern over possible contamination of drinking water supplies. In addition, the formation of haloacetic acids (HAAs) as by-products during disinfection with chlorine-based agents is still a relevant issue, since HAAs pose serious health hazard. In this work, we investigated the affinity of a precursor of Al-MCM-41 (a mesostructured hexagonal aluminosilicate containing the template surfactant) towards nitrate and HAAs, for its possible application in the removal of these pollutants from natural and drinking waters. Additionally, adsorption kinetics and iso