| 초록 |
Biodiesel is a renewable, biodegradable, and nontoxic fuel that can be used in diesel cars without requiring modification of existing engines. Biodiesel, a fatty acid methyl ester, is commercially produced through transesterification of vegetable oils or animal fats. Since the amount of waste coffee grounds (WCG) is continuoulsy increasing, we produced biodiesel from WCG in the one-step direct process. WCG was found to contain approximately 16.5 % of lipid, and it was easily extracted with over 95 % efficiency. However, biodiesel conversion was less than 40 %. We devised two-stage operation strategy, one stage for extraction and the other for transesterification, in the one-step direct process. In the first stage, hexane was added and operated at room temperature, followed by the second stage where methanol was added at high temperature (i.e., 70 oC). With this simple strategy, we achieved 95 % of biodiesel conversion. When we decreased the temperate at second stage to 50 oC, biodiesel conversion was still over 90 %.
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