RSM optimization of ultrasound-assisted melia dubia oil extraction with green solvents and their suitability for diesel engine applications

Abstract

Melia-dubia, a member of the neem family, is recognized as a promising biodiesel feedstock due to its higher oil content. Hence, this study uses an ultrasound-assisted extraction method to focus on oil extraction from Melia-dubia seeds. Response surface methodology using a 3-factor, 3-level Box-Behnken design (BBD) optimized the oil yield using environmentally friendly solvents such as 2-Methyl tetrahydrofuran, Cyclopentyl methyl ether, and ethanol. They were utilized in the range of 4–8 mL/g. A maximum of 50.5 % yield was achieved using 2-methyl tetrahydrofuran solvent at the solvent-to-solid ratio of 6.98 mL/g at an extraction time of 87.6 min. Furthermore, the GCMS reveals the presence of higher levels of palmitic and linoleic acids in Melia-dubia oil. The obtained biodiesel was tested in a single-cylinder diesel engine at different BMEP values, where the MD20 blend exhibited a 3.75 % increase in brake thermal efficiency compared to diesel at higher BMEP conditions. Additionally, CO and smoke emissions demonstrated significant reductions of 13.08 % and 27.1 % for MD10, as well as 9.83 % and 16.78 % for MD20 blends, respectively, to the baseline diesel fuel. However, it is worth noting that there was a slight increase in NOx emissions for all blends compared to diesel.