Solvent extraction through a double-pass parallel-plate membrane channel with recycle

The reflux indeed has much influence on the heat and mass transfer, which i n turn plays a significant role on the design, calculation, and operation o f the equipment. The effects of recycle on membrane extraction through a do uble-pass parallel-plate channel have been studied both theoretically and e xperimentally. Theoretical analysis of mass transfer in multipass membrane extractors was analogous to heat transfer in multipass heat exchangers. Exp eriments were carried out with the use of a membrane sheet made of micropor ous polypropylene coated with polytetrafluoroethylene as a permeable barrie r to extract acetic acid from aqueous solution by methyl isobutyl ketone. T heoretical predictions are in qualitative agreement with the experimental r esults. Contrast a single-pass parallel-plate membrane channel without recy cle, considerable improvement in mass transfer is obtainable if membrane ex traction is operated in a double-pass' device of same size with recycle whi ch provides the increase of fluid velocity and pre-extraction (or pre-mixin g) effect. It is found that recycle can enhance mass transfer, especially f or operations with higher inlet volume rate or shorter conduit length. (C) 1999 Elsevier Science B.V. All rights reserved.