PROJECT SUMMARY REPORT
Biodiesel Production from Waste Feedstock
Submitted To
The 2012 Academic Year NSF AY-REU Program
Part of
NSF Type 1 STEP Grant
Sponsored By
The National Science Foundation
Grant ID No.: DUE-0756921
College of Engineering and Applied Science
University of Cincinnati
Cincinnati, Ohio
Prepared By
Anna Greve, Junior, Civil Engineering
Kathe Pocker, Pre-Junior, Biomedical Engineering
Report Reviewed By:
Dr. Mingming Lu
Dr. Urmila Ghia
College of Engineering and Applied Science
University of Cincinnati
January 7 – April 12, 2013
Sponsored By
The National Science Foundation
Grant ID No.: DUE-0756921
Biodiesel Production from Waste Feedstock
January 7 – April 12, 2013
Presented by
Anna Greve, Junior, Civil Engineering
Kathe Pocker, Pre-Junior, Biomedical Engineering
College of Engineering and Applied Science
University of Cincinnati, Cincinnati, Ohio
Goals and Objectives of Project:
As petroleum diesel becomes more expensive, more difficult to produce and continues to harm
the environment, interest in alternative energy sources is increasing. Biodiesel in particular has gained
attention over the years. Biodiesel is an alternative diesel fuel that can be produced from vegetable oils,
recycled restaurant greases, or animal fats by reacting with alcohol and in some circumstances a
catalyst. Transesterification is the most common method used to produce biodiesel from vegetable oils.
The triglycerides from the vegetable oils and alcohol, often times methanol, are converted into esters (the
biodiesel) and glycerol, and a catalyst (commonly sodium or potassium hydroxide) is often used to speed
up the reaction.6 The chemical reaction for the production of biodiesel by transesterification is as follows:
Figure 1: General transesterification equation9
Petroleum diesel has been a reliable source of energy over the years, but many problems with its
use have arose. These problems include the fact that these sources are not sustainable, dependency on
foreign countries for oil, high costs, and the inevitable negative environmental impact. In contrast,
biodiesel serves as a renewable resource with a very low environmental impact.7 The physical properties
of biodiesel are similar to those of petroleum diesel, but biodiesel is a cleaner-burning alternative and
significantly reduces emissions of toxic air pollutants and greenhouse gases. While biodiesel can be used
in its pure form (B100, meaning 100% biodiesel), it is commonly blended with petroleum diesel. One of
the current disadvantages is that use of blends higher than B5 (5% biodiesel, 95% petroleum diesel) is
not currently approved by most automakers. There are also concerns circulating that B100 may be
harmful to car engines, especially at lower temperatures.3 Another issue with current biodiesel production
is the cost of the raw materials, as anywhere from 70-95% of total biodiesel production costs come from
raw material expenses.2
The goal of this project is to examine biodiesel as a practical energy resource, as well as to work
on refining the process of biodiesel production from waste feedstock in order to reduce cost and time and
make biodiesel a more practical energy source. Utilizing waste feedstock as a source for biodiesel
production (as opposed to corn ethanol or soy beans) creates a useful purpose for an otherwise harmful
waste product and also helps reduce the cost of biodiesel production. Being able to diminish biodiesel
production costs and the time associated with biodiesel production would help to further reduce
dependency on fossil fuels and make biodiesel a more viable alternative to petroleum diesel. More
specifically, this project has two main objectives: to determine how variation in reaction times affects the
biodiesel yield, and to further examine the effects of using various waste coffee ground mixtures (5%
NaOH, 5% KOH, and 10% KOH) to produce biodiesel.
Research Tasks Undertaken:
Methodologies and Results:
During this project, biodiesel was produced from waste cooking oil (WCO) and waste coffee
grounds (WCG). Both extractions required different techniques, and aspects of each extraction were
varied as part of this research project.
The WCO utilized in this project was obtained from the Cincinnati Zoo and Botanical Gardens and
from the dining hall facilities located on the University of Cincinnati campus. To extract biodiesel using
WCO, the first step was to perform a small titration using 1 mL WCO, 10 mL ethanol, and 2 drops of an
indicator. 0.01% NaOH solution was added in 0.5 mL or 1.0 mL increments until the solution turned pink.
At that point, the amount of NaOH that was needed to be added to a larger amount of WCO in order to
neutralize all the acid could be calculated. After this calculation was done, the correct amount of NaOH
could be obtained (0.35 g catalyst plus the amount needed to neutralize the acid) and was dissolved in 20
mL of methanol. This solution was then set on a heat/stir plate to dissolve. Once all of the NaOH was
dissolved, the solution was added to 50 or 100 mL of WCO. After adding a stir bar and covering the
beaker with parafilm, the solution was set on a heat/stir plate at 60 o C - 65o C to heat and neutralize for a
period of time ranging from twenty minutes to one hour (see Figure 2). Once the solution was heated, it
was poured into a container and allowed to separate (see Figure 3). The biodiesel is a light gold color that
settles on the top, while the glycerol is a dark brown color that settles on the bottom (see Figure 4). When
a clear distinction between the two layers was visible, the glycerol was removed and the biodiesel was
washed with water approximately three times. Washing was done to ensure that any leftover NaOH or
other chemicals were removed, and water was poured slowly to ensure no emulsion was formed. The
biodiesel was removed from the opposite end of the container than the water and glycerin were. This was
done to ensure that any remaining water does not contaminate the biodiesel. The biodiesel was then
weighed so that a percent recovery could be obtained.
Figure 2: Checking the temperature of the WCO solution
Figure 3: Pouring the biodiesel and glycerol solution into flask to allow for separation
Figure 4: Biodiesel and glycerol before separation (left), after separation (middle), and during water wash (right)
The WCG used in this project were obtained from the Starbucks facilities on the University of
Cincinnati campus. Conversion of biodiesel from WCG first required 5.0 g of the WCG to be weighed out.
Various types of pre-prepared WCG were used (samples contained either 5% KOH,10% KOH, or 5%
NaOH). Next, 200 mL of methanol was added, a stir bar was put in the beaker, the beaker was covered
with parafilm, and the mixture was stirred and heated at 60o C - 65o C. The reaction was allowed to occur
for two and a half hours, with 1.5 mL samples being taken every half an hour so that the purity of the
biodiesel extracted at each time could be determined through later analysis (see Figure 5). After two and
a half hours, the solution was taken off of the heat source and left in the refrigerator to cool, and the next
day the methanol was removed via evaporation in a rotary evaporator (see Figure 6). This device heats
the methanol/biodiesel solution, and allows the methanol to be evaporated and used again during future
experiments. The biodiesel remained behind in the flask, which was then rinsed with a small amount of
methanol to remove any biodiesel that adhered to the wall of the flask. This solution was poured into a
graduated cylinder, and any remaining methanol was evaporated either by heat, by airstream, or by a
combination of both.
Figure 5: Extraction of WCG solution
Figure 6: Use of the rotary extractor to separate the biodiesel and methanol
The percent yields of the biodiesel production from the WCO are shown in Figure 4. To determine
these yields, the amount of biodiesel produced was divided by the starting amount of WCO for each
variation of reaction time. Each reaction time was tested with two separate samples, and Figure 4
displays the average percent recoveries for each reaction time. The average percentage of biodiesel
produced was 88.47%. The results are as follows:
Figure 4: Reaction Time vs. Percent Recovery Biodiesel
The results of this experiment indicate that variation in reaction times can alter the amount and
purity of biodiesel produced. Although the data shows that a very short reaction time (twenty minutes)
appears to have the highest extraction rate, the biodiesel produced from this reaction time was likely
much less pure than the others. This is due to the fact that there was likely unreacted WCO remaining in
the biodiesel because of the short reaction time allocated. Unfortunately, the purity of each time sample
was unable to be tested in the course of this project. Looking at the overall trend, though, this data
indicates that the longer the reaction time, the greater the yield of biodiesel produced from the WCO.
After the methanol, NaOH, and WCO had been combined, it was necessary to let the solution sit until the
glycerol had settled to the bottom. The settling time varied based on how long the reaction was allowed to
proceed, and these results are seen in Figure 5 below.
Figure 5: Reaction Time vs. Time Required to Settle
This data indicates a downward trend, meaning that the longer the reaction is allowed to proceed,
the less time is necessary to let the glycerol settle to the bottom of the container. This information does
not affect the purity or amount of the biodiesel produced, but it does impact the overall amount of time
required for biodiesel production. It also shows that even though the shorter reaction times may obviously
be less time consuming, it takes longer for those samples to settle and in the end the amount of time
required for each sample is relatively similar.
One of the benefits of extracting biodiesel (not only from waste cooking oil but from all biodiesel
production processes) is that the main byproduct, glycerol (also known as biodiesel glycerin or glycerine),
can be removed and utilized. Glycerol is a thick, colorless, and odorless liquid that can be used for
medical, weapon, and cosmetic industrial productions. Before it can be used, though, glycerol must be
filtered and transformed into 100% pure glycerin. This process safely purifies the crude biodiesel glycerol
and turns the otherwise hazardous waste into an environmental-friendly alternative. The glycerol is
filtered by fractional vacuum distillation or chemical reactions, depending on what degree of purity is
desired.
The percentage of glycerol produced during these experiments stayed more consistent than the
percentage of biodiesel produced, as can be seen by comparing the two graphs. The average amount of
glycerol recovered was 17.01%.The following graph (Figure 6) shows the percent recovery of glycerol
from these experiments:
Figure 6: Reaction Time vs. Glycerol Yield
While better purification processes are needed for glycerol to be fully utilized, it has great
potential and is a useful byproduct to biodiesel production. Glycerin can then be used in drug fabrication,
as a moisturizing agent in soaps and other body products, in food processing, as a fertilizing agent, and in
weapon production.5 A number of companies including Cargill, Dow Chemical, Solvay, and Archer
Daniels Midland have also announced planned construction of new chemical facilities using glycerin as
feedstock.4 Being able to sell a byproduct makes the biodiesel production process more economically
viable. The price of glycerin has varied over the years.
Conclusions:
Currently, the world relies on a few major sources, mostly fossil fuels, for energy. These sources
are running out, though, and they are becoming more expensive and harmful to the environment.
Biodiesel is similar in terms of physical properties to petroleum diesel, but it is a much cleaner-burning
alternative, it is a sustainable resource, it allows independence from foreign countries to produce fuel, and
it makes good use of waste products such as restaurant greases that can be difficult to dispose of
properly. The research presented here validates successful production of biodiesel from waste cooking oil
and waste coffee grounds. Increasing reaction time during WCO extraction overall appeared to result in a
higher percentage of biodiesel yield, along with shorter separation times. The amount of glycerol
produced remained fairly constant across reaction times. Waste coffee ground extractions were also
performed successfully, and in the future, purity of these samples will be assessed. One of the current
obstacles to biodiesel production is the cost, particularly that associated with the raw materials. In order
for biodiesel use to become widespread, production and material costs must decrease. The use of waste
feedstock brings down these prices, but the purity of the biodiesel produced needs to be further
assessed. These results need to be explored further to see if reaction time can in fact be reduced with
WCO extraction so that production costs could decrease on a large scale. It is evident, though, that
biodiesel should continue to be researched and used as an alternative energy source.