Gas-liquid-liquid flow patterns and extraction in a rotating microchannel extractor

The flow patterns of gas-liquid-liquid three-phase fluids in the rotating microchannel extractor (RME) were studied in this paper. The kerosene-water system without mass transfer and the 2%P507-22%NaH₂PO₄ system with mass transfer were considered. The influence of interfacial tension, microchannel structure, and rotation rate on three-phase flow patterns were investigated. Eight different flow patterns such as droplet-continuous flow, long droplet-continuous flow, filiform parallel-continuous flow, filiform parallel-filiform parallel flow, small droplet-continuous flow, filiform parallel-small droplet flow, small droplet-small droplet flow, and continuous-filiform parallel flow were observed. The results showed that the proposed universal flow pattern map can effectively predict the flow patterns of the two systems and the small droplet-small droplet flow has the best effect of extracting Fe³⁺ from the 2%P507-22%NaH₂PO₄ system. The traditional first-order equilibrium extraction efficiency was 102% while the percentage extraction was up to 85% (14.4 mg/L) after one stage extraction and about 97.9% (2.0 mg/L) after two-stage extraction.