Partition function 75-------------------percolation

If a solid substance is extracted repeatedly with several portions of cold solvent, the operation is called maceration, if the same operation is carried out with hot solvent, it is called digestion and if the procedure has a countercurrent character, it is called percolation. So-called Soxhlet extractors, in which a solid substance is extracted with a solvent and the extract becomes more and more concentrated, function automatically. If a dissolved substance is extracted with one portion or more of an immiscible solvent, the operations is called simple extraction or multiple extraction, respectively. If the extraction is carried out by countercurrently-moving solvents, we deal with a countercurrent distribution technique. A continuous extraction of a liquid with another liquid immiscible with the first is called perforation continuous countercurrent extraction using two liquid phases is carried out in special countercurrent columns. If one of the phases is fixed on a carrier, partition chromatography is the name given to the operation. The choice of the given type of extraction method will depend on the character of the analyzed substances and on the required separation efficiency. 

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