Impact of methanol addition strategy on enzymatic transesterification of jatropha oil for biodiesel processing

The potential of Jatropha curcas seed oil for biodiesel production is well recognized. Lipase transesterification of triglycerides is an eco-friendly alternative to chemical process. However, intoxication by methanol hampers further applicability of enzymatic transesterification. This study investigated the impact of methanol adding on transesterification efficiency for jatropha oil with methanol from 40 to 60 °C. For stepwise addition, the conversions by using methanol were from 33 to 42% at 24 h. For continuous addition, the conversions by using methanol were from 47 to 64%. Higher empirical first-order rate constants and favorable energetics for the first 6 h also demonstrated the advantages of the gradient addition over stepwise addition. Faster ME conversion for palmitic acid (C16:0) of jatropha oil was found, as well as the negative impact of double bonds of linoleic acid (C18:2) on methanolytic transesterification by both adding methods.

► Methanol addition for jatropha oil was kinetically and energetically investigated.
► Gradient methanol addition was demonstrated by significantly greater conversions.
► Impacts of fatty acid on enzymatic transesterification were firstly demonstrated.
► Findings of the present study assist scale-up operations in the future.