In the presence of the as-prepared catalyst, the free fatty acid (FFA) conversion
reached 98.17% after 3 h, and the fatty acid methyl ester (FAME) yield reached 87.57% after 15 h. By contrast,
the typical solid acid catalyst Amberlyst-15 obtained only 95.25% and 45.17% FFA conversion and
FAME yield, respectively. Thus, the prepared catalyst had a high catalytic activity for simultaneous esterification
and transesterification. In addition, the catalyst had excellent stability, thereby having potential
use as a heterogeneous catalyst for biodiesel production from WCO with a high FFA content.