In the supercritical state, the supercritical carbon dioxide is contacted with the substance to be separated to

selectively extract the components with different polarity, boiling point and molecular weight. Of course,

the extract obtained corresponding to each pressure range cannot be single, but the conditions can be controlled

to obtain the best proportion of mixed components,and then the supercritical fluid can be changed into ordinary gas

by means of decompression and heating, and the extracted substances can be completely or basically precipitated,

so as to achieve the purpose of separation and purification. Therefore,
the supercritical fluid carbon dioxide extraction process is a combination of extraction and separation.