4.3. Factors affecting RSO transesterification process
Transesterification of RSO to synthesize biodiesel is affected by number of factors. The parameters considered in this review are as follows:
4.3.1. FFA content of RSO
The FFA content of rubber seed oil is reportedly high, 23.471–45 wt.% [16], [31], [40] and [50]. The reduction of FFA values of crude RSO is significant to avoid soap formation and downstream processing problems when a homogeneous base catalyst is used in transesterification reaction [17], [40], [48], [53] and [55]. Homogeneous acid catalyst such as H2SO4 is employed in esterification of the oil with alcohol to reduce the FFA to less than 1 wt.% prior to transesterification. Catalyst concentration followed by alcohol/oil ratio is the most influential parameters compared to reaction temperature and time [40].