The biodiesel reactions were performed in a three-necked round-bottom flask of 250 mL fitted with a water-cooled
condenser and thermometer. Agitation was performed simultaneously by a mechanical stirrer. The catalyst was first activated by dispersing it in methanol at 40 C with constant stirring for 40 min. After the catalyst activation, required amount of WCO (heated at 100 C for 1 h prior to the reaction)was added to the reactor and the reaction was carried out under the identified reaction conditions. After reaction completion, the reaction mixture was filtered through a Whatman 42 filter paper (125 mm diameter and a pore size of 2.5 mm) and then centrifuged to separate the catalyst completely.