Mixing performance and drug nano-particle preparation inside slugs in a gas–liquid microchannel reactor

Abstract

This work presents quantitative measurements of the mixing performance inside the liquid slugs of the gas–liquid Taylor flow in a Y-shaped microchannel in comparison with the mixing of liquids in conventional single-phase laminar flow microchannels by using μ-LIF technique at low and medium Reynolds numbers. First, stratified flow and vortex flow for water–ethanol system were obtained in the single-phase laminar flow system in a Y-shaped micro-contactor. Then, the fundamentals of steady intermittent flow pattern with independent bubbles and slugs in a gas–liquid Taylor flow system were investigated in the same microchannel. It turns out that with the introduced gas phase, the parallel symmetric flow of the liquid in the stratified and vortex flow regime is rigorously disarranged, which enhances the liquid mixing performance inside the individual slugs. This enhancement is due to the squeezing effect as well as the recirculation flow in the slugs. Then we applied these two systems to study the mixing sensitive process, i.e., the anti-solvent precipitation of the curcumin nano-particles. Nano-particles with good appearance and a narrow size distribution were prepared in the gas–liquid microchannel reactors at low Re numbers.