Reduction of FFA in jatropha curcas oil via sequential direct-ultrasonic irradiation and dosage of methanol/sulfuric acid catalyst mixture on esterification process

• Published in: Energy conversion and management 2014-12, Vol.88, p.1078-1085
• Main Authors: Andrade-Tacca, Cesar Augusto, Chang, Chia-Chi, Chen, Yi-Hung, Ji, Dar-Ren, Wang, Yi-Yu, Yen, Yue-Quen, Chang, Ching-Yuan
• Format: Article
• Language: English
• Subjects: Catalysts; Density; Dosage; Esterification; Intervals; Irradiation; Methyl alcohol; Reduction
• ISSN: 0196-8904
• DOI: 10.1016/j.enconman.2014.09.054

Production of jatropha-ester (JO-ester) from jatropha oil (JO) under sequential direct-ultrasonic irradiation (UI) with auto-induced temperature rise followed by adding a mixture of methanol/sulfuric-acid catalyst (M/C) dose between high temperature intervals was studied. Comparisons with various doses of 5, 10,16.6 and 25 mL at different temperature intervals of 108.9-120 [degrees]C, 100-120 [degrees]C, 85-120 [degrees]C and 75-120 [degrees]C respectively were performed. System parameters examined include: esterification times (t sub(E)) for UI, settling time (t sub(S)) after esterification and temperature (T). Properties of acid value (AV), iodine value (IV), kinematic viscosity (kV), density ([rho] sub(LO)) and water content (m sub(w)) of JO and JO-ester product were measured. The esterification conversion efficiencies ([eta]) were determined and assessed. An [eta] of 99.35% was obtained at temperature interval of 108.9-120 [degrees]C with 5 mL per dose for 20 doses and t sub(E) of 167.39 min (denoted as Process U sub(120-5)), which is slightly higher than [eta] of 98.87% at temperature interval of 75-120 [degrees]C with 25 mL per dose for 4 doses and t sub(E) of 108.79 min (noted as Process U sub(120-25)). The JO-ester obtained via sequential UI with adding doses of 5 mL possess AV of 0.24 mg KOH/g, IV of 124.77 g I sub(2)/100 g, kV of 9.89 mm super(2)/s, [rho] sub(LO) of 901.73 kg/m super(3) and m sub(w) of 0.3 wt.% showing that sequential UI and dose at higher temperature interval can give higher reduction of AV compared with 36.56 mg KOH/g of original oil. The effects of t sub(S) and t sub(E) on AV are of minor and moderate importance, respectively. The combined effects of auto-induced temperature-rise of UI and temperature higher than boiling point of methanol used improve the mixing and esterification extent.