Extraction, characterization, and utilization of biodiesel from Bani (Pongamia pinnata (L.) Pierre)
2012
Razal, R.A.
Bani (Pongamia pinnata (L.) Pierre) seeds were extracted using soxhlet apparatus to determine which among hexane, cyclohexane, and petroleum ether would be a more suitable solvent for extraction of bani oil. Seed moisture content, the presence of seed coat, and grinding of the seeds affected oil yield by solvent extraction. Hexane, which is relatively lower in cost than cyclohexane, proved to be a practical solvent for sundried uncoated ground bani seeds, showing bani oil content of up to 56% with soxhlet extraction. However, simple soaking of the ground bani seeds in hexane provided lower oil recovery compared with solvent extraction. Experiments to determine effects of soaking time, seed mass-to-solvent ratio, and soaking temperature showed favorable soaking time and temperature of 8 hrs and 35 deg C, respectively, while oil recovery increased as seed-mass-to-solvent-volume ratio was varied from 1:2 to 1:6. Beyond the 1:6 ratio, increases in the seed-mass-to-solvent-volume ratio did not result in significant increases in oil recovery. Important physico-chemical properties of the solvent-extracted oil were determined, showing a specific gravity of 0.92764 + or - 0.0052 at 250 deg C, saponification number of 195.7 mg KOH/g oil, iodine value of 56.35 g l2/100 g oil, and a free fatty acid value of 5.41 mg KOH/g oil. The extracted oil was refined through degumming and acid esterification. Biodiesel was prepared by transesterification of the refined oil with methanol in the presence of sodium hydroxide as catalyst. The most favorable oil-to-methanol-to-catalyst obtained is 1:8:0.2 at a reaction temperature of 45 deg C. TLC analysis showed that the oil is composed of 94.27% methyl ester. Biodiesel properties of the tranesterified oil were determined, showing flashpoint 84 deg C, water and sediments less than 0.025% v/v, kinematic viscosity 5.5 mm sg/s, sulfated ash 0.25%, and copper chrome corrosion test No. 1a.
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