Abstract
[Display omitted]
•MgO/CaO composite of nanorod shape was synthesized as a basic heterogeneous catalyst.•It was used in the transesterification of castor oil by normal stirring and sonication mixing.•The best yield by normal mixing is 96.2 % after 75 min and 98.8 % by sonication mixing after 60 min.•The sonication mixing reduce greatly the time, methanol content, temperature and catalyst mass.•The catalyst is of high reusability and the products match the international standards.
MgO/CaO nanorods (MgO/CaO NRs) were synthesized using a diatomite substrate under the microwave irradiation. The synthesized composite exhibits well-developed rod-like morphology with 112.8 m2/g BET surface area. The synthetic MgO/CaO NRs were evaluated as a potential catalyst in the transesterification of non-edible castor oil into biodiesel. The catalyst achieved stunning catalytic performance with biodiesel yield of 96.2 % within 70 min using 6 wt.,% of it as loading value after fixing the temperature at 70 °C and the ethanol-to-the used castor oil molar ratio at 15:1 by normal mixing. The sonication effect resulted in an enhancement in the yield to about 98.8 % after 60 min only and reduced the required ethanol, catalyst dosage and temperature. The characterization of the resulted castor oil-based biodiesel by the two mixing technique is of strong matching with the qualifications of EN 14214 as well as the ASTM D-6571 international standards of biodiesel.