Controllable and high-throughput preparation of microdroplet using an ultra-high speed rotating packed bed

Abstract

Microdroplets and their dispersion, with a large specific surface area and a short diffusion distance, have been applied in various unit operations and reaction processes. However, it is still a challenge to control the size and size distribution of microdroplets, especially for high-throughput generation. In this work, a novel ultra-high speed rotating packed bed (UHS-RPB) was invented, in which rotating foam packing with a speed of 4000–12000 r·min−1 provides microfluidic channels to disperse liquid into microdroplets with high throughput. Then generated microdroplets can be directly dispersed into a continuous falling film for obtaining a mixture of microdroplet dispersion. In this UHS-RPB, the effects of rotational speed, liquid initial velocity, liquid viscosity, liquid surface tension and packing pore size on the average size (d32) and size distribution of microdroplets were systematically investigated. Results showed that the UHS-RPB could produce microdroplets with a d32 of 25–63 μm at a liquid flow rate of 1025 L·h−1, and the size distribution of the microdroplets accords well with Rosin–Rammler distribution model. In addition, a correlation was established for the prediction of d32, and the predicted d32 was in good agreement with the experimental data with a deviation within ± 15%. These results demonstrated that UHS-RPB could be a promising candidate for controllable preparation of uniform microdroplets.