Kinetic study on lipase-catalyzed biodiesel production from waste cooking oil

• A kinetic model was established to simulate the enzymatic biodiesel production from waste cooking oil.
• The kinetic model can adequately simulate reaction results under different conditions.
• Methanol step-feeding experiments were conducted verify the validity of the kinetic model.

A kinetic model of the biodiesel production from waste cooking oil using Candida sp. 99-125 lipase as catalyst was established in this paper. The limited reaction steps in the model were considered to be the hydrolysis of glycerides and the esterification of free fatty acids, while the methanolysis of glycerides were considered to be negligible. Matlab programming platform was used to estimate the parameters of the model. A series of experiments were conducted to verify the validity of the model. The results showed that the model could adequately simulate the reaction results of biodiesel production at different lipase loadings, substrate ratios and initial water concentrations. The agreement between experimental data and calculated values was good, which could prove the validity of the kinetic model. Moreover, the results of biodiesel production using a twelve-step methanol feeding method and a three-step methanol feeding method could be simulated well by the kinetic model. The results indicated that the model could also simulate the biodiesel production using methanol step-wise addition.

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