Solar demulsification: Towards the oil-water interface broken of solar photo-thermo-electro coupling

Abstract

The stability of the emulsified oil/water mixture depends on the strength and tightness of the interface, which is closely related to the adsorption and close packing of the active components on the interface. The core task of demulsification is to change the interface properties to enhance efficient oil-water separation. In this study, a coupling model of photo field, thermo field, and electro field was constructed to focus on fully considering the particularity of the demulsification, while improving the utilization efficiency of solar energy by presetting and matching a variety of energy flows and sub-processes. Taking oil/water emulsion from the ASP flooding as an example, the oil removal rate of 82.27% can be obtained, and efficient energy modes, namely high-intensity thermo field, uniform photo field and low-intensity electro field, are established. At the same time, the results show that the photo-thermo-electro field changes the properties of the oil-water interface, such as the interfacial tension, zeta potential and modulus. The mechanism of solar demulsification is that the solar thermal effect changes the motion state of the molecules at the interface, the coupling electro effect drives the migration of charged droplets and the stretching or deformation of the polymer chain, which combined with the photo field to degrade the polymer at the interface. Solar demulsification not only enables innovation in the form of energy and promotes its sustainable development, but also provides a green process in which solar thermo, photo, and electro are synergistically combined to achieve demulsification.