Staged Versions of Liquid Membrane Extraction Processes

The application of the liquid membrane technique to the system consisting of serially connected mixer-settler extractors is suggested and evaluated. A comparative theoretical analysis of various flow schemes of contacting liquids in series of mixer-settler extractors has been performed. It is shown that the scheme of a staged version of supported liquid membrane provides the highest extraction efficiency. One laboratory plant consisting of eight mixer-settler was examined with the standard extraction system water-acetone-toluene using two schemes: with internal (the extractant recycles between each pair of extraction and stripping stages) and external (the extractant first passes through all the stages of extraction, then through all stripping stages) circulation of the extractant. The effectiveness of the first variant (supported liquid membrane scheme) was considerably higher than that of the second scheme. Good agreement between theory and experiment was established.