The temperature of the oil mixed with the methanol mixture will be measured and the experiment consists of five different solutions of KOH + methanol that will each be reacted with the vegetable oil. A magnetic stirrer will be used in the process to get the reaction going and afterwards the finalised solution will be placed in a centrifugal and the process of centrifugation will separate the solution into glycerol and biodiesel. The biodiesel will then be extracted to give a reading on percentage yield.
The method was personally derived and many modifications were made to the initial standard procedure of mixing 50% concentration Potassium Hydroxide solutions with 10ml of vegetable oil and stirring on a magnetic stirrer for 10-15 minutes at a certain temperature was deemed to unsafe for students as the high concentration acid was extremely corrosive, had irritating effects and also raised environmental concerns as the organic waste disposal process was far more complicated when the substances would permeate a trash landfill. As a result the new method was made and the substances involved were altered significantly. The new method consists of a reaction with a 5g/100ml (KOH concentrated) mixture between potassium hydroxide and methanol. In each test, there is a varied use in the concentration of the methanol mixture and this is measured by an arbitrary percentage figure as well as a known uncertainty. Furthermore, the potassium hydroxide serves as a catalyst for the reaction.
Equipment Used:
Method:
-
To set up the equipment appropriately, use a 10cm3 Measuring Cylinder to measure out 10ml of vegetable oil, and keep aside separately. Measure 1.5ml of the 5g/100ml (1%) Potassium Hydroxide solution and place set aside in the measuring cylinder. Set up the magnetic stirrer, and measure the temperature of the oil using the thermometer. For this experiment, the oil (placed inside beaker) will need to be kept on the magnetic stirrer with the capsule inserted and heated to 31ºc. Measure the mass of the empty beaker first using the mass balance and record.
- Once the oil has been heated to the appropriate temperature, add the methanol-KOH solution with 1% concentration to the oil and allow the stirrer to stir at a constant temperature for approximately ten to fifteen minutes. After a few minutes of stirring and any visible physical/chemical changes have occurred, remove the beaker of mixture from the solution and set aside temporarily.
- The methyl-ester biodiesel mixture is ready for centrifugation. Using the mass balance, measure out the mass of the beaker with the oil mixture that has just undergone transesterification and pour all the substance from the beaker into a centrifugal tube.
- Repeat all the tests with the 2%,3%,4% and 5% concentration KOH mixtures in methanol. When repeating, remember to measure each separate beakers individual mass and use the stirrer to bring the temperature back up to 31º. Once the temperature has hit 31º, mix the KOH with the oil as done before and allow the stirrer to create a reaction between the substances. Keep making qualitative observations and recording changes in temperature from the reaction and record the mass of the final solutions once stirring.
- Finally, once all the products have been reacted, place them in centrifugal tubes and insert the tubes into the centrifuge. The centrifugation process will separate the biodiesel and glycerol. Extract the thin biodiesel layer (on top), measure the mass of the biodiesel in the initial beaker and derive the percentage yield of biodiesel from the mass difference between the solutions, density from mass and volume and make observations on the mass obtained.
Diagram of Process : Done On Skitch
Variables:
Safety And Environmental Measures:
Plenty of glassware will be utilised throughout the experiment, and therefore it is essential that safety glasses are worn as extra precaution to protect eyes from broken glass. Furthermore, all glassware should be kept away from the edges of tables to prevent risk of damage.
KOH – methanol mixture is labeled as an irritant and mildly
corrosive based on *Cleaps Hazcards and it is therefore advised to wear gloves. It is also advised to wear lab coats as products of transesterification may permanently stain clothing.
Fortunately, there are no ethical concerns involved as only vegetable oil is being used and no animal substances. The biodiesel substance is biodegradable and can be easily disposed of in organic waste.
*Cleaps cited in Bibliography
Analysis:
Raw Data:
Qualitative Observations:
- In all tests after the oil was placed into the centrifuge, a gunky substance was formed from the separation into two layers, one being the biodiesel and it can be assumed that the gunky substance was glycerol (used in soaps).
At times the position of the magnetic stirrer was not in place for some results, which may be a result of random error (anoma
- lies) in results such as the 2% concentration.
- The temperature of the magnetic stirrer would be set higher than 31º, and many of the substances would exceed or be under the temperature of 31º before the actual reaction began.
- The volume of the oil and KOH mixture used in the second test may not have been the same amount as the first, which would cause an error in the percentage yield of biodiesels.
Data Processing:
2% Conc. 3% + 2% + 10% + 0.08% = 15.08% ≈ 4.99g ± 20%
3% Conc. 2% + 2% + 10% + 0.08% = 14.08% ≈ 6.84g ± 10%
4% Conc. 1% + 2% + 10% + 0.08% = 13.08% ≈ 7.81g ± 10%
5% Conc. 1% + 2% + 10% + 0.08% = 13.08% ≈ 7.97g ± 10%
Processed Data Table:
Literature Value For Density: 0.88 g/cm3 — Average Density from results: 1.23 ± 0.31
Literature value for Density of biodiesel produced from transesterification re
action produced specifically from vegetable oil. Taken from source2
Systematic % Error: | 1.23 - 0.88 |
————- x 100
0.88
= 40% (2sf) Systematic Error uncertainty
Graph Of Data: Density
The data for 3% concentration has been omitted as it appears to be an anomalous result, that may have occurred from random error.
Further Example Calculations (+ Observations included):
Graph for % yield:
Refer at end of document** (Page 11)
Graph for mass obtained:
Conclusion:
Multiple inferences can be made from the data obtained. Firstly the clean burning renewable fuel has been formed from a derived method, in which a transesterification reaction has occurred between Methanol and Vegetable oil (using potassium hydroxide as a catalyst). It was expected that the increase in concentration of the KOH would cause a greater percentage and mass yield of biodiesel. Fortunately this expectation was met with the results provided, although there were a few given anomalies formed from the systematic errors present, it was evident that the experiment did match the initial hypothesis of an increase in biodiesel yield.
Although the conclusion states than an increase in concentration of the KOH - Methanol substance would increase the yield of biodiesel in the product of transesterification, it must be understood that there were many imprecisions and boundaries for error were relatively high throughout the experiment. The primary reason for this is that only one test was conducted for each concentration, rather than gathering an average for each results, which was a result of time management problems.
Despite the causes of error and uncertainties, the calculated average density of biodiesel produced was 1.23gcm-3. The literature value for this was given above (0.88) and this value has been taken from an experiment in which the yield of biodiesel was taken from vegetable oils using both sodium hydroxide and potassium hydroxide as the catalyst in the experiment. The experimental error for the density was extremely high, being around 40%.
The general formula for calculating systematic error in experiments is as such:
“Experimental error = {(Literature Value - Calculated Value) ÷ (Literature Value)} x 100 “
The experimental error is actually the sum of the systematic and random error, (error which could influence one single result), and therefore varies for each result obtained. However the graph for the density shows the rising increase. Although a clean line of best fit cannot be placed upon the graph, it is clear that there is a steady rise in the output of biodiesel against the increase in initial concentration. It is evident that there was a random error for the 2% concentration with the mass output measured. This may have been a result of some of the substance spilling onto the stirrer during one of the measurements, when equipment was not handled appropriately. Since this only affected a single result, it was omitted from the graph, and the line of best fit was not inclusive of this result. Despite this, the error bar uncertainties are relatively high for the mass output, and therefore the min and max gradients vary highly, which means any value for output within this range would be regarded a systematic error in the experiment.
In the density graph, the curve of best fit is exponential, and does not include the result obtained for 3% concentration, as this also appears to be slightly anomalous. It could also be regarded a random error as the gradient of the curve does not fit into the boundaries of uncertainty for this result. Reasons for this uncertainty could be a result of any of the limitations explored in the evaluation. Finally the percentage yield graph also has somewhat of a linear relationship between the output of biodiesel as a percentage of the total substance and the concentration increase together.
The diagram (figure 4) shows a successful gathering of biodiesel, in which the top layer represents the biodiesel and the bottom layer the glycerol. There were other different physical appearances for other results (not photographed).
Evaluation:
Works Cited:
"Biodiesel Basics - Biodiesel.org." Biodiesel Basics - Biodiesel.org. Biodiesel Org, n.d. Web. 11 May 2015.
Button, Scott. "Biodiesel: Vehicle Fuel From Vegetable Oil." Energy & Environment 21.8 (2009): 1305-324. Web.
Jamil, Cut Aisya Z., and (Ijera). Performance of KOH as a Catalyst for Trans-esterification of Jatropha Curcas Oil (2012): n. pag. 12 Mar. 2012. Web. 13 May 2015.
"Secondary Science Hazcards." Secondary Science Hazcards. N.p., n.d. Web. 13 May 2015.
Images:
"The Chemistry of Biodiesel | Biodiesel Project | Goshen College." Academics. Goshen College, n.d. Web. 13 May 2015.
All other images were personally taken and diagrams constructed using Skitch.
GRAPH OF PERCENTAGE YIELD OF BIODIESEL: