KINETICS AND OPTIMIZATION OF LIPASE-ASSISTED ESTERIFICATION OF ISOAMYL PROPIONATE IN SOLVENT-FREE SYSTEMS

Abstract

The research work emphasizes on optimization of parameters and kinetic study associated with the enzyme-catalyzed reaction of isoamyl alcohol and propionic acid in a solvent-free system. The synthesis of ester was carried out in the 50 mL baffled glass reactor with immobilized lipase (Candida Antarctica lipase B) as a catalyst. The conversion of 95 % was obtained after 10 h of reaction time, at 50°C, acid to alcohol molar ratio of 1:3, enzyme loading of 2.5 % (w/v), molecular sieves 3 g, and agitation speed of 300 rpm. Immobilized enzyme was found to retain 75 % of its initial activity and was reused up to 7 cycles. The Ping Pong Bi-Bi model with substrate inhibition was best fitted with the initial rate data. The kinetic parameter values determined at optimized conditions are as follows: maximum rate constant (Vmax) = 0.05 mol/L/min, Michaelis Menten constant for acid (Ka) = 0.1 mol/L, Michaelis Menten constant for alcohol (Kb) = 1.5 mol/L, constant for acid inhibition (Kia) = 0.3 mol/L, constant for alcohol inhibition (Kib) = 1.56 mol/L.