Effect of substrate molar ratio on the yield of CG
The effect of molar ratio of CA to glycerol on the yield of CG was evaluated in the range from 1:75 to 1:175. As shown in Fig. 5, as the molar ratio changed from 1:75 to 1:125, the yields of CG increased, while they were all lower than 80% at 12 h. When the molar ratio of CA to glycerol varied from 1:150 to 1:175, the yields were similar with each other and over 95 % after 10 h, which could be attributed to the presence of excessive glycerol as reactant and reaction medium for the esterification. Therefore, the substrate molar ratio of 1:150 was chosen for the esterification in the following experiments.
Fig. 5. Effect of substrate molar ratio on the yield of CG. Reaction conditions: 25% of Lipozyme 435 (relative to the weight of total substrates), 86.7 kpa, 80 oC.