3.1.1 Effect of ethanol concentrati

3.1.1 Effect of ethanol concentration
The experiments were carried out at constant extraction
temperature of 35°C and extraction pressure
of 30 MPa. It can be seen from Figs. 3 and 4 that the
yield and content of estradiol are the highest when the
concentration of 75% ethanol solution is used as the
co-solvent and the yield and content of progesterone
are the highest when 85% ethanol solution is used as
the co-solvent. It is considered that the polarity of
progesterone is less than that of estradiol, as estradiol
has two hydroxyl groups and progesterone has one
carbonyl. With increasing concentration of ethanol-water
solution, the polarity would decrease, so that estradiol
has better solubility in 75% ethanol-water solution
than in 85%.
3.1.2 Effect of the flow rate of co-solvent
The effect of the flow rate of co-solvent was
studied at a constant pressure of 30 MPa and temperature
of 35°C while 75% ethanol solution was used
as the co-solvent. The experimental results (Figs. 3
and 4) indicate that the yield and content of estradiol
are the highest when the flow rate of co-solvent is 2.0
ml·min