Currently, the biodiesel industry is investigating non-food crops with high oil content. The industry is also evaluating oil sources from deeper into the industrial or commercial waste streams. Spent coffee grounds could be a feedstock that qualifies for both as a non-food crop and a waste product. The purpose of this study is to evaluate the feasibility of using coffee oil extracted from spent coffee grounds as raw material to produce ASTM standard biodiesel. The two biodiesel production methods that were used are acid-catalyzed esterification followed by alkali-catalyzed transesterification and lipase catalyzed transesterification. It was found that the high level of free fatty acids (FFA) in the coffee oil was reduced from 16.3% to 2.64% by acid-catalyzed esterification with 40/1 molar ratio of methanol to FFA in the presence of 5% (v/v, based on FFA) hydrochloric acid. However, poor conversion was obtained for the further alkali-catalyzed transesterification. In comparison, 98.5% conversion was achieved by using enzymatic catalysis, demonstrating the feasibility of using this approach to process low quality coffee oil from spent coffee grounds for biodiesel production.

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Abstract:The purpose of this paper is to evaluate the feasibility of using recycled canola oil as raw material to produce ASTM standard biodiesel. Two-step reaction, acid-catalyzed esterification followed by alkali-catalyzed transesterification, was performed. The high level of free fatty acids ( FFA) in the recycled canola oil was reduced to less than 1% by acidcatalyzed esterification with 40/1 molar ratio of methanol to FFA in the presence of 5% (v/v, based on FFA) sulfuric acid. Further alkali-catalyzed transesterification was carried out at 6/1 molar ratio of methanol to oil and 1% (wt%, based on oil weight) potassium hydroxide. The characterizations of produced biodiesel showed that it met the ASTM D 6751 with respect to the kinematic viscosity at 40 ºC, acid number, flash point, water and sediment, cold soak filtration test, oxidation stability, free and total glycerin etc. At the same time, the properties of by-product crude glycerol, such as flash point, moisture by Karl Fisher, ash, glycerol content, were also characterized, which can facilitate further glycerol purification and expand its applications, thus enhancing the overall profitability of the biodiesel production process.

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This study evaluated the production of biodiesel using fish oil as raw material. Two-stage alkaline-catalysis transesterification was performed with 6/1 molar ratio of methanol to oil at 55ºC in the presence of 1 wt. % base amount of potassium hydroxide (KOH). The fuel properties of the biodiesel were further analyzed. The characterizations of the produced biodiesel showed that it met ASTM D 6751 standard with respect to acid number, flash point, water and sediment, free and total glycerin, sulfur content, distillation temperature, etc. It was found that cold soak and oxidative stability were out spec due to the high amount of polyunsaturated fatty acid present in the fish oil. However, through blending with used cooking oil biodiesel, in spec biodiesel fuel could be achieved.The idea has been increasingly accepted worldwide that continued exclusive dependence on petroleum is unrealistic due to the high economic costs and security costs, together with the environmental concern. In a search for new energy sources, much attention is focused on biomass as a reliable and renewable source that is able to satisfy a significant part of global energy demands. Currently, biodiesel is considered a real alternative to diesel fuel due to the following advantages [1].1. It can reduce dependence on crude oil foreign imports and enhance energy security.2. It has favorable energy return on energy invested. 3. It can reduce greenhouse emissions and lower harmful emissions.4. It is biodegradable, nontoxic, and renewable. 5. It can help improve rural economies since the agricultural surplus is used as raw material.The most commonly used oils for the production of biodiesel are soybean [2], rapeseed [3], palm [4], sunflower [5][6], canola [7][8], and cottonseed [9][10][11][12]. However, cultivated land is generally too limited to grow enough seed-oil plants. Moreover, due to the indirect land use and food vs. fuel issue, the utilization of these feedstocks for biodiesel production has been criticized. Used cooking oil collected from restaurants is cheaper but it is a limited and unstable source for biodiesel production. Algae have promising potential; however, it is