摘要：In situ transesterification of microalgae Chlorella vulgaris with high free fatty acid (FFA) using solid acid and alkali catalyst (two-step transesterification) has been evaluated. The highest fatty acid methyl esters (FAME) yield of 35.50 ± 1.27 mg/g biomass was provided at the optimal conditions as follows: in the first step, 10 wt. % of solid acid (Amberlyst BD20) and reaction time of 50 min; in the second step, 4 wt. % of KOH for 40 min. The FAME yield obtained by two - step pre-esterification and transterification was three times more than that achieved by one-step alkali-catalyzed conversion, and the products were more suitable for biodiesel standards.
