Microwave-assisted transesterification is another possibility for biodiesel produc­tion from lipidic feedstocks with high acidity [61]. Refaat et al. [80] compared both microwave-assisted and the conventional process for producing biodiesel from high acidity feedstocks, concluding that reaction time is reduced by about 97% and sepa­ration time by about 94% using microwave irradiation.

Perin et al. [76] compared the acid-catalyzed and alkali-catalyzed trans­esterification assisted by microwave irradiation concluding that the best results are obtained under basic conditions, i. e. the reaction takes place in 5 min, and 95% conversion is obtained. Azcan and Danisman [12] have considered microwave heat­ing to perform the transesterification of rapeseed oil, showing that increased yields and reduced reaction times are possible.