Enzymatic synthesis of farnesyl laurate in organic solvent: initial water activity, kinetics mechanism, optimization of continuous operation using packed bed reactor and mass transfer studies |
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Authors: | Rahman N K Kamaruddin A H Uzir M H |
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Institution: | (1) School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang, Malaysia; |
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Abstract: | The influence of water activity and water content was investigated with farnesyl laurate synthesis catalyzed by Lipozyme RM
IM. Lipozyme RM IM activity depended strongly on initial water activity value. The best results were achieved for a reaction
medium with an initial water activity of 0.11 since it gives the best conversion value of 96.80%. The rate constants obtained
in the kinetics study using Ping-Pong-Bi-Bi and Ordered-Bi-Bi mechanisms with dead-end complex inhibition of lauric acid were
compared. The corresponding parameters were found to obey the Ordered-Bi-Bi mechanism with dead-end complex inhibition of
lauric acid. Kinetic parameters were calculated based on this model as follows: V
max = 5.80 mmol l−1 min−1 g enzyme−1, K
m,A = 0.70 mmol l−1 g enzyme−1, K
m,B = 115.48 mmol l−1 g enzyme−1, K
i = 11.25 mmol l−1 g enzyme−1. The optimum conditions for the esterification of farnesol with lauric acid in a continuous packed bed reactor were found
as the following: 18.18 cm packed bed height and 0.9 ml/min substrate flow rate. The optimum molar conversion of lauric acid
to farnesyl laurate was 98.07±0.82%. The effect of mass transfer in the packed bed reactor has also been studied using two
models for cases of reaction limited and mass transfer limited. A very good agreement between the mass transfer limited model
and the experimental data obtained indicating that the esterification in a packed bed reactor was mass transfer limited. |
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Keywords: | |
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