Experimental parametric analysis of biodiesel synthesis in microreactors using waste cooking oil (WCO) in ethilic route

This study investigates biodiesel synthesis from waste cooking oil (WCO) using a microreactor completely 3D printed in metal. Production of biodiesel from WCO will inevitably lead to higher levels of free fatty acids (FFAs), since a hydrolysis reaction occurs with the water from food, turning triglycerides into FFAs when the refined vegetable oil is used for cooking. To overcome the negative effects of the FFA content on mass transfer and ultimately tend to decrease the ester conversion, its amount in oil feedstock must be reduced to lower values than 0.5% through a pretreatment step of esterification with an acid catalyst. Therefore, the two chemical processes were here parametrically investigated in an ethylic route: first, the reduction of the FFAs in the WCO using an esterification pretreatment, and then the conversion of the remaining triglycerides through an alkali-catalyzed transesterification. The partial factorial Taguchi analysis was used to explore parametric effects and greatly reduce the number of experiments needed. A biodiesel conversion of 98% was achieved at a temperature of 55 °C which is very close to the industrially acceptable level of conversion, but in only 2 min, which is much lower than the reaction times using traditional batch reactors.