Preparation of biodiesel by coupling extraction and transesterification

A new method coupling the two-phase solvent extraction(TSE) and the transesterification to prepare biodiesel was studied.Investigations were carried out to obtain biodiesel(fatty acid methyl esters)by transesterification of methanol and rapeseed oil-hexane solution coming from TSE process in the presence of sodium hydroxide as the catalyst.The influence factors of transesterification such as reaction time,catalyst dosage,molar ratio of methanol to oil and reaction temperature were optimized.The results showed that the optimal reaction parameters were as follows:sodium hydroxide dosage 1.1%(based on the weight of rapeseed oil),molar ratio of methanol to oil 9∶1,reaction time 120 min,and reaction temperature 60℃.Under these conditions,the triglyceride conversion rate was up to 98.2%.The new method has the merits of simple process and less wash water,which are favorable for reducing the cost of biodiesel production.