Studies of the acid-catalyzed system have been very limited in number. No commercial biodiesel plants to
date have been reported to use the acid-catalyzed process. Despite its relatively slow reaction rate, the acidcatalyzed
process offers benefits with respect to its independence from free fatty acid content and the consequent
absence of a pretreatment step. These advantages favour the use of the acid-catalyzed process when
using waste cooking oil as the raw material