Synthesis of activated carbon from biodiesel waste as a sustainable environmental method using microwave heating

There is a significant concern about the increased by-products generated by the high demand for biodiesel. Therefore, reducing the consequences of waste disposal is particularly important, transforming such waste into materials with added value. In this work, activated carbons (ACs) were prepared from biodiesel waste (crude glycerin) by chemical activation, and microwaves as the energy source in the thermal conversion using full factorial experimental designs. The crude glycerin was impregnated with H 3 PO 4 and activated in a N 2 atmosphere. The results showed that the activation time is a critical factor in the specific surface area (S BET ), and the impregnation ratio is a significant factor in the total pore volume (V 0.95 ). The best AC was obtained at 1000 W, the activation time of 12 min, and the impregnation ratio of 1:3 (m glycerin :m H3PO4 ), resulting in 500 m 2 g −1 and 0.55 cm 3 g −1 for S BET and V 0.95 , respectively. In addition, the obtained ACs showed a maximum adsorption capacity of about 55 mg g −1 for amoxicillin. Thus, crude glycerin was a promisor raw material for preparing ACs using the microwave as a heat source.