Synergistic Mechanisms Between Nanoparticles and Surfactants: Insight Into NP–Surfactant Interactions

Effectiveness of Polysorbate Polyester on Separation of Emulsions Made by Green Surfactants

“…Emulsions with MCO were also tested with DIW and low-salinity emulsions with the addition of positively charged (SiO 2 ) and negatively charged (Fe 3 O 4 ) nanoparticles. Nanoparticle-containing emulsions present a different interaction with the surfactant; adsorption will occur between the surfactant and the liquid–liquid interface and the solid–liquid interface, obtaining a reduction in surface tension and solid–liquid interfacial energy, respectively. , This interaction will be determined by the surface charge of the nanoparticle and the head charge of the surfactant. Only two of the surfactants were tested as salinity was involved, and GZ emulsions are not considerably stable.…”

“…The first thing to consider is the repulsion-assisted diffusion mechanism. Repulsive Coulomb interactions among surfactants and nanoparticles with the same charge will encourage surfactant diffusion to the liquid–liquid interface . This might have as a result an increase in emulsion stability, as there would be more surfactant molecules at the interface, making the emulsion more difficult to separate.…”

“…This interfacial activity can redistribute the surfactant present at the interface through desorption and move the molecules onto the MNP surface. If the MNPs can stay at the interface, the diminishment of the interfacial area will support interfacial tension reduction . The positioning of the MNPs at the interface would tend to stabilize the emulsion.…”

“…Repulsive Coulomb interactions among surfactants and nanoparticles with the same charge will encourage surfactant diffusion to the liquid−liquid interface. 33 This might have as a result an increase in emulsion stability, as there would be more surfactant molecules at the interface, making the emulsion more difficult to separate. The second mechanism to consider is the NPs' ability to be adsorbed onto the droplet; this does not reduce the interfacial tension as with the surface active agents but creates a network on the droplets and therefore control coagulation, reducing the demulsification.…”

“…If the MNPs can stay at the interface, the diminishment of the interfacial area will support interfacial tension reduction. 33 The positioning of the MNPs at the interface would tend to stabilize the emulsion. The very small separation that was achieved with the demulsifier might be due to the fact that it was not only a surfactant at the interface but also MNPs, in which the combination appears to be more difficult to demulsificate.…”