Biofuels: Producing Ethanol from Cellulosic Material
Genel Bakış
Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
In this experiment, cellulosic material (such as corn stalks, leaves, grasses, etc.) will be used as a feedstock for the production of ethanol. The cellulosic material is first pretreated (ground and heated), digested with enzymes, and then fermented with yeast. Ethanol production is monitored using an ethanol probe. The experiment can be extended to optimize ethanol production by varying the feedstock used, pretreatment conditions, enzyme variation, yeast variation, etc. An alternative method of monitoring the reaction is to measure the carbon dioxide produced (using a gas sensor) instead of the ethanol. As a low-tech alternative, glucose meters (found in any drug store) can be used to monitor the glucose during the process, if an ethanol probe or carbon dioxide gas sensor is not available.
With an increased emphasis on ‘inquiry-based learning”, scientific probes are becoming more popular. Handheld devices like the Vernier Lab Quest used in conjunction with a variety of probes (such as those for conductivity, dissolved oxygen, voltage, and more) allow for less focus on collecting data and/or making graphs and more on analyzing the data and making predictions. Another advantage is that these are small and lightweight and can be taken into the field for measurements.
Prosedür
1. Sample Preparation
Select cellulosic material to be used as feedstock. This can be corn stalks, grasses, leaves, pet bedding, or paper.
Using a ball mill grinder (or coffee grinder if ball mill grinder is not available), grind feedstock into a fine powder with no large pieces remaining.
Measure 1.0 g of feedstock and place in a 50-mL centrifuge tube. Label the tube with the feedstock chosen.
Label a second 50 mL centrifuge tube as “Control”. Do
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Sonuçlar
The % ethanol in the solution will be displayed on the handheld tablet screen using the software related to the brand of the ethanol sensor used (Figure 2).
Representative results of the percent ethanol produced by various feedstocks can be seen in Table 1.
Feedstock
Ethanol produced
Sawdust
0.7
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Başvuru ve Özet
The Energy Independence and Security Act of 2007 set into law a renewable fuel standard. It created a phase-in for renewable fuel volumes starting at 9 billion gallons in 2008 and ending at 36 billion gallons in 2022. Of that 36 billion, it was expected that 16 billion of that would come from cellulosic materials. For 2014, the original proposal was for 18.15 billion gallons of renewable fuel, 1.75 billion of that coming from cellulosic material. Unfortunately, based on the volume of cellulosic ethano
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Referanslar
The Energy Independence and Security Act of 2007. United States Congress, Washington DC. January 4, (2007).
Balat, M., Balat, H., Oz, C. Progress in bioethanol processing. Progress in Energy and Combustion Science.34 (2008).
Ragauskas, A.J., Williams, C.K., Davison, B.H., Britovsek, G., Cairney, J., Eckert, C.A., Frederick Jr, W.J., Hallett, J.P., Leak, D.J., Liotta, C.L., Mielenz, J.R., Murphy, R., Templer, R., Tschaplinski, T. The Path Forward for Biofuels and Biomaterials. Science.311 484 (2006).
Demirbas, A. Bioethanol from Cellulosic Materials: A Renewable Motor Fuel from Biomass. Energy Source.27 327-337 (2005).
Select cellulosic material to be used as feedstock. This can be corn stalks, grasses, leaves, pet bedding, or paper.
Using a ball mill grinder (or coffee grinder if ball mill grinder is not available), grind feedstock into a fine powder with no large pieces remaining.
Measure 1.0 g of feedstock and place in a 50-mL centrifuge tube. Label the tube with the feedstock chosen.
Label a second 50 mL centrifuge tube as “Control”. Do not put any feedstock in this tube.
2. Pretreatment
Set up a 500-mL beaker with approximately 400 mL of water on a hotplate and heat to a gentle boil.
Add 25 mL of distilled water to the 2 centrifuge tubes. Swirl to mix. Put the cap on the centrifuge tubes loosely.
Put the centrifuge tubes in the beaker full of gently boiling water. Be sure that water from the water bath does not leak into the tubes. Let boil for 30 min.
Let tubes cool to room temperature.
3. Enzymatic Digestion
Add 1 mL of cellulase enzyme to both tubes.
Put tubes in an incubator at 50 °C for 24 h.
Allow the tubes to cool to room temperature.
4. Fermentation
Add 1.0 g of active yeast (regular grocery store yeast is ok) to each of the centrifuge tubes. Swirl to mix.
Put an airlock on top of the centrifuge tube. The airlock allows CO2 to escape, keeping the pressure low in the centrifuge tube.
Place the centrifuge tubes in a rack and put in an incubator at 37 °C for 24 h.
Using an ethanol sensor, measure the ethanol concentration in the control tube (Figure 1). Ethanol sensors can be purchased through Vernier or PASCO for approximately $100 each. Figure 1. Ethanol probe measuring the ethanol concentration in the control tube.
Using an ethanol sensor, measure the ethanol concentration in the sample tube (Figure 2). Figure 2. Handheld tablet displaying % of ethanol.