The synthesis between palmitic acid and methanol was carried out in a w/o reverse microemulsion prepared from the mixture of dodecylbenzenesulfonic acid (DBSA)/isooctane/water. Box-Behnken design was adopted to evaluate the effect of significant factors on the methyl palmitate yield and response surface methodology (RSM), which was employed to optimize the process parameters in the esterification. The conditions that showed optimal results for methyl palmitate preparation were: 3.33 w0 ([H2O]/[surfactant]), 4.2 h reaction time, 5:1 methanol/acid molar ratio, and 130 mg g-1 lipase ([lipase]/[acid]) concentration. The following verification experiment obtained a result of 97% in almost total agreement with the expected value (98%). The kinetic constants of the model were determined by experiments at 40 °C with initial concentrations of 0.025-0.25 mol L-1 palmitic acid and 0.025-0.3 mol L-1 methanol in the microemulsion system. The kinetic studies showed that the reaction obeyed the Ping-Pong bi-bi mechanism with inhibition by methanol.
microemulsion; lipase; esterification; response surface methodology (RSM); inhibition
