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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... 

    The stability and surface activity of environmentally responsive surface-modified silica nanoparticles: the importance of hydrophobicity

    , Article Journal of Dispersion Science and Technology ; Volume 41, Issue 9 , 2020 , Pages 1299-1310 Ghaleh, V.R ; Mohammadi, A ; Sharif University of Technology
    Taylor and Francis Inc  2020
    In this study, the effect of hydrophobicity of environmentally responsive surface-modified silica nanoparticles on the stability and surface activity of the nanoparticles is examined. To this end, n-propyl, n-hexyl, or n-octyl chains and methoxy poly(ethylene glycol) chains at various quantities were coated covalently on the surface of silica nanoparticles to regulate the hydrophobicity of the responsive nanoparticles. Various experimental tools such as stability analysis, interfacial-tension and contact-angle measurements, and emulsion formation were performed to investigate the effect of hydrophobicity. It became evident that the presence of the hydrophobic agents influences considerably...