Search for: surfactant-molecules
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    Influence of surface-modified nanoparticles on the hydrodynamics of rising bubbles

    , Article Chemical Engineering and Technology ; Volume 44, Issue 3 , 2021 , Pages 513-520 ; 09307516 (ISSN) Fayzi, P ; Bastani, D ; Lotfi, M ; Miller, R ; Sharif University of Technology
    Wiley-VCH Verlag  2021
    Local velocities of bubbles rising in four different nanosilica solutions were investigated experimentally. Also, the density, viscosity, and surface tension of fumed nanosilica and modified nanosilica solutions were measured. Heat treatment and chemical functionalization were used to modify the properties of silica nanoparticles. It was found that the addition of nanosilica affected the hydrodynamics of the rising bubble by increasing the drag friction at the interface. However, environmentally responsive nanosilica particles behaved like surfactant molecules, due to the interfacial activity of hydrophilic and hydrophobic chains. Silica nanoparticles coated with both hydrophilic and... 

    A note on the synergistic effect of surfactants and nanoparticles on rising bubble hydrodynamics

    , Article Chemical Engineering and Processing - Process Intensification ; Volume 155 , 2020 Fayzi, P ; Bastani, D ; Lotfi, M ; Sharif University of Technology
    Elsevier B.V  2020
    Various mixtures of surfactants and nanosilica particles were investigated to assess their influence on rising bubble hydrodynamics. For this purpose, local velocities of rising bubbles were measured experimentally. Also, the effects of concentration of three types of surface-modified silica nanoparticles on density, viscosity, and surface tension of surfactant solutions were determined. Experimental results revealed that the simultaneous presence of nanoparticles and surfactant molecules led to the decrease of local velocities of rising bubbles. The presence of nanoparticles in surfactant solutions leads to a more reduction of bubble local velocity. This could be caused by the formation of... 

    Influences of polymer-surfactant interaction on the drop formation process: an experimental study

    , Article Langmuir ; Volume 37, Issue 3 , 2021 , Pages 1025-1036 ; 07437463 (ISSN) Dastyar, P ; Salehi, M. S ; Firoozabadi, B ; Afshin, H ; Sharif University of Technology
    American Chemical Society  2021
    The interaction between polymer and surfactant molecules affects the physical properties of liquids, which could be of great importance in an abundance of processes related to drop formation. Polymer and surfactant concentration is a factor that dramatically impacts the shape of molecular networks formed in the fluid bulk and the characteristics of a forming drop. In this study, the deformation and detachment of aqueous carboxymethyl cellulose (CMC) solutions' drops containing different concentrations of sodium dodecyl sulfate (SDS) are studied experimentally. Our purpose is to determine the effects of CMC and SDS concentrations on the parameters related to the formation process, including... 

    Mixed protein-surfactant adsorption layers formed in a sequential and simultaneous way at water-air and water-oil interfaces

    , Article Soft Matter ; Volume 8, Issue 22 , 2012 , Pages 6057-6065 ; 1744683X (ISSN) Dan, A ; Kotsmar, C ; Ferri, J. K ; Javadi, A ; Karbaschi, M ; Krägel, J ; Wüstneck, R ; Miller, R ; Sharif University of Technology
    Mixed protein-surfactant adsorption layers can be built up in two different ways. The classical way is when all components adsorb simultaneously from a mixed solution. Alternatively, the components adsorb one after another, i.e. in a sequential way. In the present work, the formation of such surface layers has been studied with the random coil protein β-casein in the presence of added anionic surfactant SDS and compared for two different interfaces: the water-air (W-A) and water-hexane (W-H) interfaces. The used experimental technique is a drop profile analysis tensiometer PAT-1 specially equipped with a coaxial double capillary for drop volume exchange during the experiments. The results... 

    Wettability alteration and oil recovery by spontaneous imbibition of low salinity brine into carbonates: Impact of Mg2+, SO4 2− and cationic surfactant

    , Article Journal of Petroleum Science and Engineering ; Volume 147 , 2016 , Pages 560-569 ; 09204105 (ISSN) Karimi, M ; Al-Maamari, R. S ; Ayatollahi, S ; Mehranbod, N ; Sharif University of Technology
    Elsevier B.V  2016
    A large amount of the discovered oil reserves are reserved in carbonate formations, which are mostly naturally fractured oil-wet. Wettability alteration towards more water-wet state reduces the capillary barrier, hence improving the oil recovery efficiency in such reservoirs. In this study, wettability alteration towards favorable wetting state was investigated by combining modified low salinity brine with surfactant during water flooding. The diluted brine was modified by increasing the concentration of Mg2+ and SO4 2−, individually as well as both ions in combination. Different brine formulations were tested experimentally through the observations of contact angle measurements and... 

    Impact of sulfate ions on wettability alteration of oil-wet calcite in the absence and presence of cationic surfactant

    , Article Energy and Fuels ; Volume 30, Issue 2 , 2016 , Pages 819-829 ; 08870624 (ISSN) Karimi, M ; Al-Maamari, R. S ; Ayatollahi, S ; Mehranbod, N ; Sharif University of Technology
    American Chemical Society  2016
    The modification of the surface wetting characteristics in fractured oil-wet carbonate reservoirs, by reversing wettability from oil-wet to water-wet, leads to improved oil recovery. However, in order to obtain a successful oil recovery process, it is crucial to understand the active mechanisms of wettability alteration. This study looks at the effect of sulfate ions as one of the most promising wettability influencing ions on the wetting properties of oil-wet calcite; the effect is studied both with and without the presence of cationic surfactant and possible mechanisms of wettability alteration are explored. A number of analytical techniques were utilized to analyze the mineral surface... 

    Modeling self-assembly of the surfactants into biological bilayer membranes with special chemical structures using dissipative particle dynamics method

    , Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 942-950 ; 10263098 (ISSN) Yaghoubi, S ; Pishevar, A. R ; Saidi, M. S ; Shirani, E ; Sharif University of Technology
    Sharif University of Technology  2016
    The aim of this study is to simulate the self-assembly of the surfactant molecules with special chemical structure and bending stiffiness into bilayer membranes using a mesoscopic Dissipative Particle Dynamics (DPD) method. The surfactants are modeled with special chemical structure and bending stiffiness. To confirm that the novel model is physical, we determine the interaction parameters based on matching the compressibility and solubility of the DPD system with real physics of the uid. To match the mutual solubility for binary uids, we use the relation between DPD parameters and x-parameters in Flory-Huggins-type models. Unsaturated bonds can change the stiffiness of a lipid membrane,... 

    Experimental study of nanoparticle-surfactant-stabilized CO2 foam: Stability and mobility control

    , Article Chemical Engineering Research and Design ; Volume 111 , 2016 , Pages 449-460 ; 02638762 (ISSN) Farhadi, H ; Riahi, S ; Ayatollahi, S ; Ahmadi, H ; Sharif University of Technology
    Institution of Chemical Engineers  2016
    CO2 injection has proved to be the most common and efficient enhanced oil recovery techniques which leads to more residual oil recovery. Unfavorable sweep efficiency which results in fingering propagation and causes early gas breakthrough is the most challenging issue of gas flooding process. The aim of this work is to study foam stability and analyze the mobility of CO2 foam stabilized by mixture of raw silica nanoparticles and ethyl hexadecyl dimethyl ammonium bromide (cationic surfactant). The result is obtained through both dynamic and static techniques using a new adsorption index.NPS-stabilized foams are generated using Ross-Miles method. A novel index for the adsorption of surfactant...