The recycle effects on membrane extraction through a parallel-plate module with concurrent-flow first and then countercurrent flow, has been studied. Theoretical predictions are in agreement with the experimental results. Considerable improvement in performance is obtainable if membrane extraction is operated with recycle which provides the effect of increasing fluid velocity, resulting in decreased mass-transfer resistance. The influences of recycle type on the performance of membrane extraction, as well as on the fixed and operating costs, have been also discussed.
