| Summary: | 碩士 === 國立臺灣海洋大學 === 輪機工程系 === 99 === Supersound and microwave were used to assist the lipid extraction of microalgae by solvents in this study. Crude lipid extracted quantity between the supersound and microwave-assisted lipid extraction under various solvents, extracting time and power were compared. The effect of emulsified solvent on the crude lipid extraction ratio was studied as well. The experimental results show that Isochrysis galbana extracted by microwave using the solvent mixture of n-heptane and iso-propanol in 2:1 volumetric ratio had the largest extracted quantity of crude microalgae lipid which is 10.87 wt. %. The extracted quantity of the crude lipid of Isochrysis galbana is the largest, 10.45 wt. % when ultrasound-assisted extraction was used together with iso-propanol solvent. In addition, the Isochysis galbana extracted by microwave using the emulsion of n-hexane and iso-proanol had higher lipid extracted quantity than that using the mixture of the same two solvents, while the extracted lipid by the latter solvent mixture appeared linear increase with the input energy of microwave. The fatty acid compositions of Isochrysis galbana which were transesterified from crude lipid was compared with those directly from the microalgae powder and those of commercial biodiesel from waste cooking-oil. It was found that the fatty acid methyl esters from transesterification of crude microalgae lipid had higher saturated fatty acid, higher oxidative stability, kinematic viscosity and calculated cetane number while lower calculated iodine value than those from the microalgae powder. In contrast, the biodiesel from waste cooking oil had the highest fatty acids of long carbon chain and heating value among
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those three biodiesels.
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