报告人：Prof Gerald Fuller，Chemical Engineering, Stanford University, Stanford, CA 94305
时间：2018年12月3日（周一）10：00
地点： 广州市番禺区大学城外环西路230号，广州大学计算机实验楼709会议室
摘要： Asphaltenes are complex polar components of heavy oils and are only marginally stable in organic solvents. Because of this marginal solubility, they have a propensity to adsorb onto oil/water interfaces to form viscoelastic layers. This can result in a strong stabilization of water-in-oil emulsions that cause difficulties in refining operations. In addition, the contact of water against a solution of asphaltenes dissolved in a model hydrocarbon (such as toluene) induces the production of a remarkable spontaneous emulsification where micron-size water droplets, stabilize by asphaltenes, spontaneously appear. In this work, we examine the spontaneous emulsification phenomenon in the presence of asphaltenes. First, the evolution of an oil/water interface and the appearance of micron-size droplets are observed using a confocal microscope. Then, microfluidic devices are built to monitor the development of a single and multiple water drops in oil. The asphaltene concentration in solution, the solvents ratio (toluene and heptane are used) and the drop size are varied. The drop size is found to have a strong effect on spontaneous emulsification dynamics. Moreover, higher concentrations of asphaltene yields faster spontaneous emulsification phenomenon. Finally, we find that the production of spontaneously emulsified droplets is greatest in the region between two larger water drops.
