| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 103 === Microalgae, a photosynthetic microorganism, can utilize light and CO2 to grow and accumulate lipid rapidly. Therefore, microalgae is viewed as a great candidate for biofuel feedstock. However, there are still some drawbacks, such as high energy consumption in harvesting and lipid extraction process. In order to overcome these disadvantages, it is important to improve the process of producing biofuel from microalgae.
The direct transesterification (DT) method firstly disrupted the cell wall of microalgae, extracted lipids and converted them into soap with alkali-methanol by both transesterification and saponification. Then, the product of first-stage then converted into fatty acid methyl acid (FAME) by esterification with acid-methanol.
In this study, Chlorella sp. ESP-6 was used as the sources to produce biodiesel. We used Response Surface Methodology (RSM) to explore the optimal combination of reaction parameters in first-stage of DT and verified the compatibility of reaction kinetic model, either by previous method or this study proposed. The parameters included concentration of alkali-catalyst, reaction temperature, reaction time and methanol/water molar ratio.
The contribution of this study is that we used statistical tools and reaction kinetics to analyze first-stage reaction of DT system. Results showed that RSM failed to find an optimal reaction condition in first-step of DT. The most possible reason is that reaction in first-stage of DT method has approached to the maximum conversion. On the other hand, both first-order irreversible and saturation reaction kinetic model fitted well with the data of RSM experiments. Also, we found that the significant parameter in the first-stage of DT system is methanol/water molar ratio. In the future, we may continue modify the reaction kinetic models with larger scale of this process.
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