EXTRACTION OF VALUABLE COMPONENTS FROM RAW PLANT MATERIAL BY CARBON DIOXIDE IN THE SUPERCRITICAL STATE

摘要

The extraction process is widely used to remove valuable components from various raw materials. As a method of separating mixtures, the high efficiency of extraction is dictated by the fact that isolation of a specific component of a mixture is based on its chemical nature, and not on its physical properties; this makes it possible to select solvents that extract given substances most completely from the raw material. Extraction of valuable components by organic solvents has come into most widespread use as a result of the relative simplicity of the equipment employed and the existence of a broad spectrum of this type of solvents. Organic solvents have, however, a number of drawbacks, the most significant of which (proceeding from evaluation of the effectiveness of the separation process) are low selectivity and extractivity, and complexity of separation of a valuable product from the extracting agent. This stage of the process is associated with significant energy outlays. Moreover, the majority of organic solvents are toxic and dangerously explosive and flammable. This appreciably complicates the design of the extraction equipment and the conditions under which it operates. The need therefore arises to replace organic solvents by more effective extracting agents.