Abstract

The lipase-catalyzed transesterification of rice bran oil and methanol for biodiesel production in hexane was investigated. The effects of different hexane weight ratio, methanol molar ratio, reaction temperature and immobilized lipase dosage on the total conversion were systematically analyzed by response surface methodology (RSM). RSM analysis showed good correspondence between experimental and predicted values. The optimal condition was 4.058 molar ratio of methanol to oil, temperature 42.295°C, 6.86% immobilized lipase and 0.624 hexane based on rice bran oil weight. Moreover, gas chromatography mass spectrometry showed that biodiesel was mainly composed of the methyl esters of hexadecanoic, 9,12-octadecadienoic and 9-octadecadienoic acid. The fourier transform infrared spectrum of biodiesel also showed the characteristic bands of C=O, O-C-O, C=C and –(CH₂)n-.

Key words: Rice bran oil, biodiesel, response surface methodology, gas chromatography mass spectrometry, fourier transform infrared spectrum.