The reaction time is an important parameter which affects the biodiesel yield.
The catalytic activities of the CaO and 30% RHA800-800 catalyst were investigated with the reaction time varying from 0.5 to
5 h.
In Fig. 5, as the reactions attained equilibrium, the maximum biodiesel yields of the CaO and 30% RHA800-800 catalyst were 93.2% and 91.5%, respectively, and the optimum reaction time was 3 h and 4 h respectively.
However, when the reaction time was further prolonged, there was a slight decrease for the biodiesel yield.
The taking place of this phenomenon could be owing to the solubility of biodiesel in glycerol [29].