A study on the application of ultrasonic wave for the production of biodiesels from blended tung oil

• Main Authors: Do Van Manh, 曼杜凡
• Other Authors: Ching-Yuan Chang
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/96222706534440266189

博士 === 國立臺灣大學 === 環境工程學研究所 === 100 === In this study, the effects of system parameters on the transesterification yield (YF) of biodiesel from tung (Vernicia fordii) and blended oils with CH3OH and KOH, and on key properties of biodiesel such as acid value (AV), iodine value (IV), kinematic viscosity (KV), density and cold filter plugging point (CFPP) were investigated. The background experimental conditions were as follws. The blended oil is consisted of 20, 50 and 30 wt.% of tung, canola and palm oils, respectively. The molar ratio of methanol to oil (M/O) and KOH catalyst concentration (MC) are 6:1 and 1 wt.%, respectively. Temperature (TR), ultrasonic frequency (fUS) and ultrasonic power (PWUS) were kept at 20 to 30 oC, 20 kHz and 270 W, respectively. The sample volume (VL) was 390 mL. The ultrasonic irradiation time (tUS) was set in the range of 1-30 min. The results showed that YF reaches high value of 87-91% for tung-oil biodiesel as tUS ≥ 5 min, while of about 92-94% for blended-oil biodiesel as tUS ≥ 1 min. At tUS = 10 min, the properties of biodiesel produced from tung oil are with AV of 0.11 mg KOH/g, IV of 159.36 g I2/100 g, KV of 9.17 mm2/s, density of 905 kg/m3 and CFPP of -16 oC, while those from blended oil are with AV of 0.11 mg KOH/g, IV of 120.35 g I2/100 g, KV of 5.54 mm2/s, density of 887 kg/m3 and CFPP of -5 oC. Comparing these values with the ASTM-D6751 standards with AV < 0.5 mg KOH/g, KV = 1.9-6 mm2/s and density = 860-900 kg/m3 points out that the tung oil should be blended with other oils in order to produce biodiesel satisfying the biodiesel standards. Moreover, the results indicated that a certain enough time, say 5 min, is needed to provide sufficient cavity heating and mixing via ultrasonic wave ensuring good properties of biodiesel produced. The KV of biodiesel using blended oil decreases from 6.26 mm2/s at tUS = 1 min to 5.54 mm2/s at tUS = 5 min, thus meeting the ASTM-D6751 value of 1.9-6.0 mm2/s. Effective performances of biodiesels produced from tung oil and blended oil consisting 20, 50 and 30 wt.% of tung, canola and palm oils employing ultrasonic irradiation also were elucidated. The YF and KV, which are essential key indices to tung-oil derived biodiesel, were measured. Appropriate conditions of TR, MC, tUS, settling time (tS) and M/O were identified. The background conditions were PWUS = 270 W, TR = 25 oC, M/O = 6, MC = 1 wt.%, tUS = 5 min and tS = 10 min. The YF increases while the KV beneficially decreases with increasing TR to 60 oC. As MC increases to 2 wt.%, the YF reaches plateau value of 98% for both tung-oil derived biodiesels without and with blending with further reduction of KV. High YF is achieved at short tUS of 5 min using MC of 2 wt.%. Steady sate is approached at tS = 30 min. At MC = 2 wt.%, tUS = 5 min, tS = 30 min and M/O = 6, the YF and KV respectively are 98.33% and 4.26 mm2/s at TR = 25 oC, while are 99.68% and 4.08 mm2/s at TR = 60 oC for the blended-oil biodiesel. Thus, the suitable conditions for the effective production of tung-oil derived biodiesels applying ultrasound irradiation are at: TR = 60 oC, MC = 2 wt.%, M/O = 6, tUS = 5 min and tS = 30 min. However, for the sake of energy-saving, the transesterification condition using TR of 25 oC may be employed, causing only slight reduction of YF of about 1.35% while increase of KV of about 0.18%. The properties of AV, IV and density of the blended-oil biodiesel produced at 25 oC are 0.06 mg KOH/g, 103.52 g I2/100 g and 885 kg/m3, respectively, satisfied with the standards of ASTM-D6751 and EN 14214. The corresponding CFPP of -5 oC, which is lower than 0 oC, also meets the standard of CNS 15072. The beneficial use of tung oil in pre-blended oil for the production of biodiesel was further studied at various blending compositions of tung, canola and palm oils (CBT, CBC and CBP). The effects of MC, CBT, PWUS and VL on the YF and the properties of AV, IV, KV, density and CFPP were investigated. The pre-blending of tung oil with palm oil greatly decreases the CFPP of palm-oil biodiesel, whereas the presence of canola and palm oils with tung oil reduces the IV and KV of tung-oil biodiesel. An MC of 2 wt.% was found to be appropriate. For PWUS/VL = 0.92-2.08 W/mL, CBT can be as high as 60 wt.% with 30 wt.% CBC and 10 wt.% CBP to produce biodiesel with high YF and satisfactory qualities of the said properties. The information obtained in this study is useful for the proper use of tung oil in conjunction with other edible oils for the production of biodiesel with satisfactory qualities and the rational design and operation of ultrasonically catalytic transesterification process.