فهرست نشریات علمی دسترسی آزاد ایران

A statistics based design of experiments (Central Composite Design, CCD) was used in the present work to develop an empirical model for describing, quantitatively, the methanolysis reaction of canola oil by the commercially immobilized Candida antarctica lipase, i.e. Novozym 435 in a solvent-free system. The reaction factors under study were the amount of enzyme (x1), temperature of operation (x2) and the molar ratio of methanol to canola oil (x3). The yield of methyl ester was evaluated using a second-order polynomial multiple regression model. An analysis of variance (ANOVA) showed a high coecient of determination (R2) value of 0.987, thus, ensuring a satisfactory adjustment of the regression model with the experimental data. The positive sign for the coecients of the amount of enzyme and the temperature of the reaction indicated that the yield of the methyl ester increased with increased levels of x1 from 3 to 5 and factor x2 from 25 to 35C. The negative eect of the methanol to canola oil ratio on the methyl ester yield indicated that the response level decreased as this factor (x3) increased. The methyl ester yield, 84.42%, as the highest value obtained through experiment that was in agreement with the predicted yield 89.15%, resulted with use of the optimized operative parameters when enzyme amount, reaction temperature and methanol to canola oil molar ratio were 5%, 38C and 3, respectively.