Study On The Phase Separation Of Liquid-Liquid Dispersion Systems In Microfluidic Devices

Microfluidic technology has excellent interface control ability,which can control and generate highly monodispersed micron-level droplets.At the same time,the fluid flow is highly ordered,the distribution of residence time is narrow,the mass and heat transfer distance is short,and the process is uniform in the microfluidic devices.These advantages make the mass and heat transfer processes in the microfluidic devices to be significantly enhanced compared to traditional macrofluidic devices,and at the same time,it is easier to accurate mechanism research on mass transfer,heat transfer and flow process.In this context,micro-extraction technique came into being.At present,how to realize the rapid liquid-liquid separation is one of the keys to restrict the micro-extraction technique to industrial applications.In this study,a systematic study is made on the separation mechanism and the separation performance at the microscale.A T-shaped micro-separator was designed and fabricated to realize fast and in-line separation.By modifying the surface property of the outlet capillary,the separation is adjusted from gravity-based to wettability-based.The effect of dispersion sizes,interfacial tensions,flow rates,separator dimensions and wettabilities of separator on separation performance based on gravity and wettability were systematically investigated,respectively.With a separator diameter of 1000 μm and flow ratio of 1,the throughput of dispersed phase range of 0-1000 μL/min was achieved for 100% separation,which covers the normal flow rate range in micro-systems without weakening the advantage of the small volume of the microfluidic devices.Finally,A unified mathematic model was established to describe the necessary condition for 100% separation in both the two types of separation processes.