Fractionation, cost general methods

The size exclusion chromatography, which is generally used as an analysis technique, can also serve to prepare samples by fractionation. However, this method, which will be studied in detail in Section 6, calls for rather heavy equipment which is not to be found in most laboratories, and the operation in itself is rather costly... 

An important financial element in recycling is residue disposal, whose costs are part of the overall economics of the recovery operation. Four general methods have been advanced for commercial utihzation of the hght fraction landfQl, polymer-enriched fractions, structural materials, and fuels. 

Separations for removing undesirable by-products and impurities, and making suprapure fine chemicals constitute a major fraction of the production costs. There is an enormous variety of methods for product separation and purification and many books on the subject have been published. Here, we deal with the problem in a very general way and we refer the reader to advanced books for details. Conventional techniques for product isolation and purification, such as fractional distillation, extraction, and crystallization, still predominate. Some guidelines for scale-up of these techniques and producing experimental data for scale-up are given in Chapter 5. More information on specific separation and purification techniques applied to particular problems of fine chemicals manufacture the reader can find in Chapter 6. 

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