Parameter evaluation of biodiesel production from unblended and blended Tung oils via ultrasound-assisted process

Abstract

Effective performances of biodiesels produced from Tung oil and blended oil consisting 20, 50 and 30wt.% of Tung, canola and palm oils employing ultrasonic irradiation were elucidated. The yield (YF) and kinematic viscosity (KV), which are essential key indices to Tung-oil derived biodiesel, were measured. Appropriate conditions of temperature (TR), KOH catalyst content (MC), ultrasonic irradiation time (tUS), settling time (tS) and molar ratio of methanol to oil (M/O) were identified. The background conditions were TR=25°C, M/O=6, MC=1wt.%, tUS=5min and tS=10min. The YF increases while the KV beneficially decreases with increasing TR to 60°C. As MC increases to 2wt.%, the YF reaches plateau value of 98% for both Tung-oil based biodiesels with further reduction of KV. High YF is achieved at short tUS of 5min using MC of 2wt.%. Steady sate is approached at tS=30min. At MC=2wt.%, tUS=5min, tS=30min and M/O=6, the YF and KV, respectively, are 98.33% and 4.26mm2/s at TR=25°C, while are 99.68% and 4.08mm2/s at TR=60°C for the blended-oil biodiesel. Thus, the suitable conditions for effective production of Tung-oil based biodiesels applying ultrasound irradiation are at: TR=60°C, MC=2wt.%, M/O=6, tUS=5min and tS=30min. However, for the sake of energy-saving, the transesterification condition using TR of 25°C may be employed, causing only slight reduction of YF of about 1.35% while increase of KV of about 0.18%. The properties of acid value, iodine value and density of the blended-oil biodiesel produced at 25°C are 0.06mg KOH/g, 103.52g I2/100g and 885kg/m3, respectively, satisfied with the standards of ASTM-D6751 and EN 14214. The corresponding cold filter plugging point of −5°C, which is lower than 0°C, also meets the standard of CNS 15072.