Nephelium lappaceum oil: A low-cost alternative feedstock for sustainable biodiesel production using magnetic solid acids

Waste seed of Nephelium lappaceum or rambutan fruit with high fat content is a promising raw material for low-cost biodiesel production. Solid acids, such as SiO2-SO3H/CoFe2O4 and superhydrophobic poly(vinylsulfonic-co-divinylbenzene) (PVS-DVB), were synthesized and characterized via X-ray diffraction, vibrating sampling magnetometer, field enhanced scanning electron microscopy-energy dispersive X-ray, and transmission electron microscopy. The magnetic catalysts possessed a mesoporous structure with an average diameter of 100 nm. The transesterification rate could reach 39%, 68%, and 98% when SiO2-SO3H/CoFe2O4, PVS-DVB, and H2SO4 acid were used, respectively, at 65 degrees C for 4-10 h. The magnetic acids were readily recovered and reused with negligible activity loss. Fatty acid methyl ester (FAME) was determined through gas chromatography-mass spectrometry. The effects of oil-to-methanol molar (O/M) ratio, reaction time, and catalyst amount on FAME conversion were studied to optimize the transesterification conditions. Rambutan oil biodiesel is within the specifications of the American Standard Test Method (ASTM D6751) and European standards (EN 14214). (c) 2015 American Institute of Chemical Engineers Environ Prog, 35: 603-610, 2016