Effects of Surfactant and Hydrophobic Nanoparticles on the Crude Oil-Water Interfacial Tension

Surfactants and nanoparticles play crucial roles in controlling the oil-water interfacial phenomenon. The natural oil-wet mineral nanoparticles that exist in crude oil could remarkably affect water-oil interfacial characteristics. Most of recent studies focus on the effect of hydrophilic nanoparticles dispersed in water on the oil-water interfacial phenomenon for the nanoparticle enhanced oil recovery. However, studies of the impact of the oil-wet nanoparticles existed in crude oil on interfacial behaviour are rare. In this study, the impacts of Span 80 surfactant and hydrophobic SiO2 nanoparticles on the crude oil-water interfacial characteristics were studied by measuring the dynamic and equilibrium crude oil-water interfacial tensions. The results show the existence of nanoparticles leading to higher crude oil-water interfacial tensions than those without nanoparticles at low surfactant concentrations below 2000 ppm. At a Span 80 surfactant concentration of 1000 ppm, the increase of interfacial tension caused by nanoparticles is largest, which is around 8.6 mN/m. For high Span 80 surfactant concentrations, the less significant impact of nanoparticles on the crude oil-water interfacial tension is obtained. The effect of nanoparticle concentration on the crude oil-water interfacial tension was also investigated in the existence of surfactant. The data indicates the less significant influence of nanoparticles on the crude oil-water interfacial tension at high nanoparticle concentration in the presence of Span 80 surfactant. This study confirms the influences of nanoparticle-surfactant interaction and competitive surfactant molecule adsorption on the nanoparticles surfaces and the crude oil-water interface.

Adhesion Phenomenon of Liquid Metals

In this chapter, we study an interfacial phenomenon between liquid metals and ceramic substrates. Therefore, investigation of these phenomena is of great importance not only in technological applications but also in fundamental understanding of physical behavior of the adhesion between two different materials as far as their electrical structures and physiochemical properties are concerned. Moreover, adhesion energy is interpreted thermodynamically by the interfacial interactions and the nature of bonding between liquid metal and ceramic material. The adhesion energy in metal/ceramic systems is determined by using an electro-acoustical model based on the propagation of the acoustic wave in the interface and strongly depends on the electric properties of combination.

On the Thermocapillary Migration at the Liquid and Solid Aspects

Thermocapillary migration is an interfacial phenomenon that describes liquid flow on a nonisothermal surface from warm to cold regions in the absence of external forces. It is a typical lubricant loss mechanism in tribosystems. To ensure continued reliability of lubricated assemblies, knowledge of the migration capacity of different liquids and solids is needed. In the present work, migration experiments were conducted on various liquid lubricants on different solid surfaces. It was found that polar lubricants such as ionic liquids and polyethylene glycol hardly migrate on the tested surfaces, and the antimigration capacity of the polytetrafluoroethylene surface was discovered to be very high. Particular attention is paid to the migration mechanism associated with surface tension and contact angle. General guidelines for evaluating the migration capacities of different liquids on solids are proposed.