Abstract:
Chlorophyll is widely extracted for industrial applications and is a key topic of
scientific and commercial interest. Alternanthera sessilis, which is known as
mukunuwenna in Sri Lanka, is one of best selections for the extraction of chlorophyll due
to the good extraction efficiency, availability and low cost.
In this work, the optimum operating conditions for the extraction of chlorophyll from A.
sessilis using solvent extraction were studied using buffered 80% aqueous acetone. The
results revealed that the best solvent volume to A. sessilis weight ratio, which gives the
highest yield of chlorophyll, was 5 ml/g. The effect of temperature and the extraction
time on the extraction was also studied. The optimum temperature of extraction is 50°C
and the optimum time of extraction is 45 minutes. The mass transfer of chlorophyll from
A. sessilis at 20°C and 30°C was modeled mathematically, using general mass transfer
equations. The experimental results showed that the degradation of chlorophyll beyond
the temperature of 30°C is significant. The saturation solubility of chlorophyll a was
54.06 and 107.6μg/ml and that for chlorophyll b was 23.13 and 29.68 μg/ml at the
temperatures of 20 and 30°C respectively.
Furthermore, the optimum pre-processing method and the storage conditions were
studied as post harvest operations for A. sessilis. The optimum method of pre processing
was identified as mechanical grinding. For one day storage, ambient air conditions
(indoor) were the optimum conditions; and for a longer storage time it was the
refrigerator conditions (15oC).
Using the extract, commercial chlorophyll, Sodium copper chlorophyllin has produced
with a 33.3% conversion of chlorophyll and its derivatives, using a modified process. The
kinetics of degradation of chlorophyll of the produced sodium copper chlorophyllin
follows a first order relationship between the concentration and the time. The
relationship between the rate constant and the temperature follows the Arrhenius
behavior. The activation energy for chlorophyll a and b are 3.014 and 2.78 kcal/mol
respectively. The rate constants for chlorophyll a and b at different temperatures are also
obtained.
