Hydrodynamic characteristics of a novel continuous countercurrent micro-extractor

Despite the rapid development of micro-extraction technology in recent years, achieving simple and robust countercurrent micro-extraction remains a challenge. In this study, a novel rotating micro-extractor was developed, and robust continuous countercurrent flow can be successfully achieved in it. The effect of device structure, operation condition, and system physical properties on the hydrodynamic characteristics was investigated. Mathematical models were also established to predict the operating region of different flow patterns, the liquid layer thickness, and the maximum throughput. The throughput is up to 18 mL/min in our experimental range and can be further improved by simply increasing the pitch of the spiral microchannel. The increase in channel length will not reduce the maximum throughput, which is quite different from the reported countercurrent micro-extractors. The unique property enables the newly developed device to achieve both high throughput and large theoretical stages and provides a promising micro-extraction technique.