Experimental Measurement of Properties of Aqueous Foam Stabilized by Modified Silica Nanoparticles Using Surfactant

In this study, stability of aqueous foam is increased by modified nanoparticles using surfactant. To better understand the behavior of stabilized foam with nanoparticles and surfactants, foam ability, stability, wettability changes of nanoparticle, and interfacial tension versus time were investigated. The results of contact angle of calcite/crude-oil/foam agent solution showed that adding CTAB surfactant to silica nanofluid changes the wettability of nanoparticles. At a concentration of critical micelle concentration of surfactant, the nanoparticle experiences the greatest change in wettability towards hydrophobicity, and contact angle increases from 20° at initial time to 57° after 24 hours. The results showed that at the mentioned concentration, the interfacial tension reaches its maximum value. This phenomenon was attributed to the reduction of free surfactants due to adsorption on the nanoparticles. Stability and foaming behaviors were investigated by Ross-Miles method. Foam stabilized with nanoparticles at low hydrophobic values at the beginning of life had a linear decay diagram similar to foam stabilized with surfactant alone. Therefore, the initial stability of the foam is controlled by the free surfactant. Later, the stability of the foam is controlled by the nanoparticles and increases substantially as the bridging mechanisms become more prominent, maximum capillary pressure increases, and viscosity of the liquid bulk increases. At high levels of nanoparticle hydrophobicity (close to CMC 1), the nanoparticles act as surfactants and no longer have the sharp linear drop observed in other samples with low adsorption values. Therefore, the beginning of the foam life is controlled by both nanoparticles and free surfactant. The results showed that the foaming behavior of foam generating solutions is similar to the interfacial tensile behavior. Also, the change in wettability of nanoparticles, which had a long equilibrium time, was proposed as a mechanism for high stability of nanoparticle-stabilized foam in the second half of its life.