Influence of Surface‐Modified Nanoparticles on the Hydrodynamics of Rising Bubbles

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 hydrophobic agents had a stronger effect on the interfacial properties than those coated only with the hydrophobic agent. Local velocities of bubbles rising in four different nanosilica solutions were studied experimentally, measuring the density, viscosity, and surface tension of the fumed nanosilica and modified nanosilica solutions. The addition of nanosilica affected the rising‐bubble hydrodynamics by increasing the drag friction at the interface, with functionalized nanosilica behaving like surfactant molecules.