Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev

3 MACERATION, PERCOLATION AND INFUSION TECHNIQUES FOR THE EXTRACTION OF MEDICINAL AND AROMATIC PLANTS
3.5.4.2.1 Advantages
The crude drug is extracted as many times as there are receivers
(in Figure 2 there are three receivers). If more extraction stages are
required, it is only necessary to have more receivers. The last treatment of
the drug – before it is discharged – is with fresh solvent, giving maximum
extraction. The solution is in contact with fresh drug before removal for
evaporation, giving the highest possible concentration.
3.5.4.2.2 Procedure
Fill the extractor with crude drug, add solvent and circulate.
Run off to receiver 1. Refi ll the extractor with solvent and circulate. Run off
to receiver 2. Refi ll the extractor with solvent and circulate. Run off to receiver
3. Remove drug from the extractor and recharge. Return solution from
receiver 1 to the extractor. Remove for evaporation. Return solution from
receiver 2 to the extractor and circulate. Run off to receiver 1. Return solution
from receiver 3 to the extractor and circulate. Run off to receiver 2. Add
fresh solvent to the extractor and circulate. Run off to receiver 3. Remove
drug from the extractor and recharge. Repeat cycle.
3.5.4.2.3 Extraction Battery
Figure 2: Multistage extraction
In the normal percolation process, the percolate is a very dilute
solution, while the ideal situation is to obtain the maximum concentration
possible. Continuous extraction devices of battery type are used when large
amounts of a single material are handled. Such devices can be achieved by
treating percolation as a multistage process. In an extraction battery process,
a series of vessels is used and extraction is semicontinuous.
3.5.4.2.4 Equipment
An extraction battery consists of a number of vessels with interconnecting
piping. Vessels are so arranged that solvent can be added
to and the product taken from any vessel. These vessels can, therefore, be
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