Enzymatic Esterification of Ammonium Lactate with Ethanol in Organic Solvent: Kinetic Study

The kinetics of the esterification of ammonium lactate with ethanol catalyzed by Novozym 435 was investigated. The Ping-Pong Bi-Bi enzymatic mechanism with competitive inhibition by both substrates was proposed. The corresponding kinetic parameters were calculated by non-linear regression. r_max = 75.6 μmol/(g·min). The inhibition constants for lactic acid (A) and ethanol (B) were K_iA = 0.016 mol/L and K_iB = 0.38 mol/L, respectively. The model was found to be in good agreement with the experimental data. As we know, it is the first time for the kinetic study of the ethyl lactate synthesis, which used ammonium lactate as raw material and catalyzed by immobilized lipase.