Synthesis and Use of Janus SiO2 Nanoparticles for Formulating Model Heavy Oil Macroemulsions
Janus nanoparticles have applications in many fields. Particularly, the oil industry is interested in applying them for enhanced oil recovery. Within this context, there is a need to understand the influence of the factors involved in the formulation of crude oil type emulsions over their properties and rheological behavior. In this contribution, spherical SiO2 Janus nanoparticles of two different sizes were synthesized and used as surfactants for the formulation of aqueous emulsions with two model oils: namely, squalane and vacuum gas oil. Factorial experiments were designed and made to analyze the effects of the particle size of the Janus nanoparticles, the water content, the emulsification energy, and of the second and third order interactions between these variables over the droplet size distributions, polydispersity, and rheological profiles of the emulsions. On the one hand, it was found that the used Janus nanoparticles produced either water in oil (for vacuum gas oil) or oil in water (for squalane) depending on the chemistry of the oil phase. On the other hand, it was demonstrated that non-additive factors play an important role over the properties of the emulsions; especially in the case of the water in oil ones. These effects also implied non-additive correlations between the droplet size distributions of the emulsions and their rheological behavior. Therefore, this work demonstrates that simpler linear relationships do not suffice for finding the best conditions for formulating crude oil type emulsions aimed for applications such as enhanced oil recovery.