Cellulose-based+Biofuels

//Key Terms: ethanol, biofuel, cellulose, amylose, cellulose, amylase, enzyme, hydrolysis, lignin, fermentation, distillation, Benedict's Reagent. //
 * CELLULOSE BASED BIOFUELS. CLARA STAHLMANN ROEDER AND MARIE SILICIANO. **The purpose of this lab was to produce ethanol efficiently from corn, grass and pure cellulose. It was hypothesized that the most ethanol would be produced from pure cellulose, then corn, then grass clippings. 30g of cornmeal was made into a slurry with distilled water. 20 ml of a 2% amylase solution and yeast were added to the mixture was allowed to ferment. The mass of carbohydrates in 30g of corn meal was used to find the mass of pure cellulose to use. A cellulose slurry was hydrolyzed using 20 ml of a 2% aqueous cellulose solution and fermented in the same way. 30g of grass clippings were blended, frozen, crushed and then made into a slurry and fermented the same way. Each fermented mixture was distilled to extract any ethanol. Each time, the temperature held constant at 78 degrees C, the boiling point of ethanol, and boiling and condensation in the distillation apparatus were observed at that point. This indicated that ethanol was present. However, there was no measurable distillate produced at 78 degrees C. This could mean that there was not enough ethanol present to form a distillate. The mixtures were heated until a distillate was formed at 97 and 98 degrees Celsius. The densities of these distillates were found to be 0.97g/ml, 0.99g/ml and 1.0g/ml for grass, corn meal and cellulose respectively. This suggests that the distillates were mainly water, but not entirely. Ethanol could have been present in the distillate. It was then hypothesized that the lack of measurable ethanol produced was due to a lack of glucose at the beginning of fermentation. Solutions of pure cellulose, cornmeal, and grass clippings were prepared as they were previously. Enzymes were also added as they were previously. Samples of the solutions were tested after 3 hours, 24 hours, four days and five days for the presence of monosaccharides. Benedict’s Reagent, an indicator that changes from blue to red in the presence of monosaccharides, was used to determine if glucose was present. Color changes in Benedict’s Reagent indicated that a trace amount of glucose was present in the cellulose solution after three hours, and glucose was present in pure cellulose and corn meal solutions after 24 hours, four days and five days. This could indicated that in the first phase of the experiment, the enzymes were not given enough time to work. This also suggests that the grass clippings were not sufficiently pretreated.The production of ethanol from cellulose would provide an alternative to petroleum, a fossil fuel that is quickly being depleted.





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Vertès, A., Inui, M., & Yukawa, H. 2008). Technological Options for Biological Fuel Ethanol. //Jounral of Molecualr Microbiology and Biotechnology//, //15//.  Retrieved January 28, 2012, from http://content.karger.com/produktedb/produkte.asp?doi=10.1159/000111989&typ=pdf

Wyman, C, & Yang, B. (2008). Pretreatment: the key to unlocking low-cost cellulosic ethanol. //Biofuels, Bioproducts and Biorefining//, //2//(1). Retrieved January 13,  2012, from http://onlinelibrary.wiley.com/doi/10.1002/bbb.49/abstract