<Experimental Data> <Home>

Biodiesel Synthesis Analysis


The eight sampled combinations of oil, alcohol and catalyst produced varied in levels of biodiesel and glycerol separation. The densities of the samples is relatively similar, ranging from 0.85g/ml to 0.87g/ml. The densities of the sample are also similar to the density of petroleum diesel at 0.81g/ml. The light absorbance of the biodiesel samples is similar to petroleum diesel, with the most variance at 0.02. The calculated enthalpy of the biodiesel samples vary considerably but are similar to the calculated enthalpy of petroleum diesel. The differences may be due to completeness of the biodiesel synthesis reaction. Samples 3 and 7 did not produce any separation of biodiesel and glycerol, it is possibly but unlikely that a high percentage of biodiesel was produced. Additional testing would need to be conducted to determine the contents of the mixture for these samples. Additionally, sample 2 produced 3 layers, biodiesel, glycerol, and an unknown substance. Additional testing would need to be conducted to determine the content of the mixture. IR Spectroscopy (see infrared spectroscopy section below) shows that all eight of the biodiesel samples contain C=O of carbonyl bonds and C-H of alkane bonds, Additional testing would be needed to confirm the separation of the ester C-C bonds. Additionally, IR spectroscopy reveals that a higher proportion of alcohol is present in the ethanol samples (3,4,7,8) showing that not all of the ethanol was used in the reaction. IR spectroscopy showed smaller amounts of alcohol present in the methanol samples (1,2,5,6).

Significant sources of error exist in this experiment. Some of the samples used oil that was heated higher than 40 degrees C, which likely led to the vaporization of the alcohol as the oil was mixed, limiting the reaction. It is also not known why two of the samples did not produce separation layers of biodiesel and glycerol. Testing the enthalpy of a flammable liquid is best conducted in a bomb calorimeter in order to contain all of the heat produced. In this experiment the calorimetry test had a number of associated errors, but all of the errors carried across all of the samples, including the petroleum diesel. Some sources of error include: burning of the wick adding energy to the system, loss of heat to the surrounding environment, different rates of liquid absorption by the wick.

With these sources of error, it is possible to conclude that biodiesel is as viable a fuel source as petroleum based diesel, specifically from calorimetry testing and entropy calculations. Biodiesel could be considered a more efficient fuel source as it is synthesized from renewable feedstock, and uses reagents and catalysts that are not toxic or damaging to the environment. If potassium hydroxide is used then all of the byproducts of biodiesel syntheses can be used in other products, as potassium is a primary ingredient of fertilizer.

Infrared Spectroscopy:


Biodiesel Oil Molecule.jpg
Triglyceride (oil) Molecule

Biodiesel molecule.jpg
Methyl Ester (biodiesel) Molecule

IR Spectroscopy Results:

  • O-H of alcohol: 3200-3650 cm-1
  • C-H of alkane: 2840-3000 cm-1
  • C=O of carbonyl: 1690-1760 cm-1

Biodiesel IRspec Sample 1.jpeg
IR Spectroscopy - Sample 1

Biodiesel IRspec Sample 2.jpeg
IR Spectroscopy - Sample 2

Biodiesel IRspec Sample 3.jpeg
IR Spectroscopy - Sample 3

Biodiesel IRspec Sample 4.jpeg
IR Spectroscopy - Sample 4

Biodiesel IRspec Sample 5.jpeg
IR Spectroscopy - Sample 5

Biodiesel IRspec Sample 6.jpeg
IR Spectroscopy - Sample 6

Biodiesel IRspec Sample 7.jpeg
IR Spectroscopy - Sample 7

Biodiesel IRspec Sample 8.jpeg
IR Spectroscopy - Sample 8