Numerical investigations of micro-SLM extraction/stripping in a spiral channel

Micro-supported liquid membrane (micro-SLM) extraction/stripping has attracted significant research attention because of its advantages. For both design and optimization purpose, a deep understanding of the mass transfer mechanisms in the micro-SLM process is of vital importance. However, the interplay between the channel diffusion, channel convection, and membrane transfer at the microscale results in complicated mass transfer patterns. The underlying mechanisms of these patterns are still unclear. In the present study, a comprehensive 3D numerical simulation was established to investigate the mass transfer behaviors in a spiral micro-SLM device. Five different mass transfer mechanisms were determined and explained in detail. Two dimensionless numbers were defined to differentiate between these mass transfer mechanisms and to generate a mechanism zoning map. The proposed model and the zoning map are very useful in predicting the mass transfer behaviors of the micro-SLM extraction/stripping process in both a laboratory environment and the industry.