The type of alcohols used affects the synthesis reaction for biodiesel very obviously, which is perhaps because of the different dissociation degree of the five alcohols in oil phase. For alcohols, the more substituted alkyl the alcohol gets, the weaker dissociation degree the alcohol has. Therefore, the acidity decreased as the alkyl group substitution increased. Methanol can be easier to form alkoxide ions compared with the other four counterparts, which is helpful to the transesterification reaction. From Fig. 5, it is interesting that only 10.6% of biodiesel is produced when isopropanol is employed, it is supposed that the higher steric hindrance of isopropanol inhibits the ester exchange process to a great extent. In summary, methanol is the best alcohol for biodiesel synthesis.