Liquid-liquid extraction is an important operation unit in chemical processes that has been widely used in the petrochemical industry, nuclear reprocessing, and ore processing. However, conventional extraction systems, such as mixer-settlers, pulse columns, and centrifugal contactors, suffer from low efficiency, high energy consumption, and large equipment dimensions. Microextractoin provides a new option to solve these problems due to its high efficiency, safety, and small volume.
However, the existing microextraction systems are mostly cocurrent operated and the recovery efficiency can reach no higher than one theoretical separation stage. It is difficult to realize countercurrent flow at the micro-scale because viscosity and surface wetting dominate over gravity and inertial effects. Difficulty in achieving countercurrent operation has been a barrier to the application of micro-extraction.
The human cardiovascular system which transports blood to every part of the body gives us inspiration to solve the problem in the micro-fluidic system. In this work, a bionic system, analogous to the human cardiovascular system, was developed to realize countercurrent, multi-stage micro-extraction. The mass transfer performance and fluid dynamics of the system were studied. High mass transfer rates and high recovery efficiency were achieved. The system can be applied to any type of micro-extractor and may promote the application of micro-extraction in a wide variety of fields.