Week 8

In lab this week, the biodiesel process was finally started! The first step in the process was to make a stock solution of KOH and methanol. From last weeks lab, it was calculated that about 3.3g of KOH would be added to 162.8g of methanol in order for an excess reaction of 150%. After mixing the KOH and methanol, being sure that it was fully dissolved, between 27.5 and 27.8 grams of the solution was added to each sample of oil. However, there was a mistake in the calculation, and the Filtered Dewatered Sample B received 37.9g of the solution. Figure 1 shows the amount of solution added to each sample (the column furthest to the right).

Figure 1. Table of amount of KOH and methanol used.

After adding the KOH and methanol solution to each sample, the solution was placed in the shaker bath for an hour so that the reaction could occur completely. The results of the reaction did not seem normal. The figures below illustrate each sample after an hour in the shaker bath. The unfiltered, undewatered solutions had two layers, as shown in figure 2. The filtered, undewatered samples both also had two layers, as illustrated in figure 3. Finally, the filtered, dewatered sample had two layers, but the one sample had a pink layer, as shown in figure 4. This pink layer was probably from residue left on the stopper from a previous experiment.

Figure 2. Unfiltered Undewatered.

Figure 3. Filtered Undewatered.

Figure 4. Filtered Dewatered.

At this point in the experiment, the solutions would need to sit in separatory flasks so that the glycerin layer could be removed from the biodiesel layer. However, after letting the solutions sit for four days, an odd result happened. Five of the six solutions separated so that the glycerin was on top. This is backwards to most biodiesel reactions. The only solution that correctly separated was the Filtered Dewatered B, which was the solution that had extra KOH and methanol added to it. As a result, it was concluded that the reaction did not occur completely, and more KOH and methanol would need to be added. After creating another batch of KOH and methanol (the same proportionality as before), equal amounts were added to each solution and they were again placed in the shaker bath. This time, the reaction seemed to have worked! Now, the solutions were ready to be washed. 

After allowing the solutions to sit over the weekend, the glycerin layer was clearly on the bottom of the biodiesel layer, as shown in figure 5. The filtered dewatered and filtered undewatered all reacted the same, as shown in figure 6. As stated above, next week, the biodiesel will be separated from the glycerin and the washing process will be started. After this, we will test the efficiency of the biofuel to see how well the filter actually worked. 

Figure 5. Unfiltered Undewatered after reaction.

Figure 6. Filtered dewatered after reaction.