Membrane extraction through countercurrent cross-flow rectangular modules with recycle

摘要

The recycling effect on membrane extraction through a countercurrent cross-flow rectangular module was studied both theoretically and experimentally. The recycling operation has two conflicting effects. One is the increase in fluid velocity, resulting in an increased mass-transfer coefficient. This is good for performance. The other is the reduction in the concentration difference, resulting in decreased mass transfer driving force. This is bad for extraction. In contrast a device without recycling, an improvement in mass transfer is achievable if the cross-flow membrane extraction is operated using a device of the same size with recycling. It is concluded that recycling can enhance mass transfer, especially for large feed-concentration solutions with a high distribution coefficient operated under a high reflux ratio.