On the technology of CO2 Description of the technology subcritical CO2 extraction About subcritical and supercritical СО2-extractionAbout subcritical and supercritical СО2-extraction
There are two trends in СО2-extraction technology in a world nowadays: subcritical and supercritical. Parameters of subcritical extraction are: pressure 57-65 kgf/cm2, temperature 15-25°С; and supercritical extraction are: pressure 150-400 kgf/cm2, temperature of extraction 50-80°С.
The subcritical СО2 extraction is more mild and sparing to alive vegetative substance. This technology has been developing in USSR since 1958, for processing of agricultural raw material and for use in food, perfumery and medical industries mainly. For 44 years of development of this technology the vast experience of its application in different branches of the light industry is accumulated. For this time dozens modifications of laboratory and industrial-scale plants were created, as well as dozens of different compositions of received balsams (СО2-extracts) applying in many industries were designed and licensed. State standards on СО2-extracts permitting to certificate these products operate for a long time. Safety and high performance of the production technology and using of СО2-extracts are time-tested for these years.
The positive characteristics of the above-mentioned technology include the little power-consuming, ecological purity, simplicity in operation, relative cheapness of hardware manufacture.
As for the supercritical СО2-extraction, this technology is rather young and is not learnt enough, especially in a vegetative material processing and product using. This modification is much more acceptable for applying in chemical, oil producing, petroleum refining and coal processing industries. In a supercritical state, the carbon dioxide is significantly less viscous and it allows it to augment mass transfer during extraction. As a result of it, the quantity of an extracted material increases. But conditions of supercritical influence on "alive", biologically active substance, is rather hard. The combination of high temperature and of high pressure inevitably stimulates a structural change in composite molecules of biologically active materials. The consequences of it are not studied yet. Other negative moments, compared with subcritical extraction, are technical complication of hardware and its high price. Concerning economical aspects of supercritical extraction processes embodying, it is necessary to realize, that it is still too expensive, especially in a food-processing industry.
