On-demand emulsions from oscillatory two-phase shear flows

穿过液-液界面的溶剂萃取是扩散受限的过程，其依赖于一相在另一相中的分散以使相之间的表面积最大化，例如，PUREX过程中的核燃料纯化。类似地，液-液系统中的化学反应动力学，例如，芳族化合物的硝化，是由生成界面面积的速率控制的。两相的表面活性剂稳定的乳化通常用于分散它们。然而，这产生了工业设计挑战，因为在该过程之后增加了快速相分离的要求。该项目旨在提出一种纯流体动力学方法，通过外力作用产生按需无稳定剂的乳液，当外力作用中断时，乳液迅速返回分离相。具体目标有三个：a）表征依赖于惯性力、粘性力和表面张力之间竞争的基本界面破裂机制; B）根据流体性质和振动参数调整乳液性质; c）使用流体机械装置来优化按需溶剂萃取。我们将使用定量实验和Lattice-Boltzmann（LB）模拟相结合的方法来深入了解界面破裂，重点是推导两层振荡剪切流中界面破裂的简单模型（目标（a）和（B））。在这里，我们将另外表征两相系统中的界面破裂，其中一种流体表现出非牛顿性质。然后，我们转向溶剂萃取的实验室模型的开发，并提供我们的系统的概念验证，并根据振动状态评估其效率（目标（c））。该项目不仅将推进对牛顿流体和复杂流体界面破裂的基本理解，还可能为工业扩散限制过程提供新的设计解决方案。

Solvent extraction across a liquid-liquid interface is a diffusion-limited process that relies on the dispersion of one phase in the other to maximise the surface area between the phases, e.g., the purification of nuclear fuel in the PUREX process. Similarly, chemical reaction kinetics in liquid liquid systems, e.g., nitration of aromatics, are controlled by the rate of generation interfacial area. Surfactant-stabilized emulsification of the two phases is routinely used to disperse them. However, this creates industrial design challenges because of the added requirement of rapid phase separation following the process. The project aims to propose a purely hydrodynamic method to generate on-demand stabilizer-free emulsions through external forcing, which rapidly return to separated phases upon interruption of the forcing.The specific objectives are threefold: a) characterize the fundamental interface breakup mechanism which relies on competition between inertial, viscous, and surface tension forces; b) tailor emulsion properties depending on the fluid properties and vibrational parameters; c) use the fluid mechanical device to optimize on-demand solvent extraction. We will use a combined approach of quantitative experiments and Lattice-Boltzmann (LB) simulations to gain insights into interface breakup with a focus on deriving simple models for interface breakup in two-layer oscillatory shear flows (objective (a) & (b)). Herein we will additionally characterize interface breakup in two-phase systems where one fluid exhibits non-Newtonian properties. We then turn to the development of a laboratory model of solvent extraction and provide a proof-of-concept of our system and evaluate its efficiency depending on the vibrational regime (objective (c)). The proposed project will not only advance fundamental understanding of interface breakup in both Newtonian and complex fluids but also potentially offer new design solutions for industrial diffusion-limited processes.