The kinetics of wax ester synthesis from oleic acid and oleyl alcohol using immobilized lipase from Candida antartica as catalyst was studied with different types of impeller (Rushton turbine and AL-hydrofoil) to create different mixing conditions in 2l stirred tank reactor. The effects of catalyst concentration, reaction temperature, and impeller tip speed on the synthesis were also evaluated. Rushton turbine impeller exhibited highest conversion rate at lower impeller tip speed as compared to AL-hydrofoil impeller. A second-order reversible kinetic model from single progress curve for the prediction of fractional conversion at given reaction time was proposed and the corresponding kinetic parameter values were calculated by non-linear regression method. The results from the simulation using the proposed model showed satisfactory agreement with the experimental data. Activation energy shows a value of 21.77 Kcal/mol. The thermodynamic parameters of the process, enthalpy and entropy, were 21.15 Kcal/mol and 52.07 cal/mol.K, respectively. � 2010 by Japan Oil Chemists' Society.

Amino acid surfactants are high-value surfactants which have excellent emulsifying characteristics and minimal toxicity to the living body. Enzymatic synthesis of palm kernel amino acid surfactant was optimized by response surface methodology (RSM) using palm kernel olein (PKO) and l(+)-lysine catalyzed by Lipozyme RM IM. The reaction was performed in batch mode stirred tank reactor (STR) with one multi-bladed impeller. A central composite rotatable design (CCRD) was employed to evaluate the interactive effects of various parameters. The parameters were temperature (A): (40.00-70.00 �C), impeller speed (B): (100.00-400.00 rpm), substrates ratio (C): (1.00-4.00 mmol) and enzyme amount (D): (5.00-8.00 g). The optimum condition derived via RSM at fixed reaction time of 24 h was temperature; 47.50 �C, impeller speed; 323.96 rpm, substrates ratio; 3.25 mmol and enzyme amount; 7.25 g. The experimental yield was 89.03% under the optimum condition, which compared well with the maximum predicted value of 93.77%. � 2009 Elsevier B.V. All rights reserved.