Transcript PPT Qualitatively Measuring the Safety of Biodegradable Plastic

Abstract
This project demonstrated the safety of biodegradable eating utensils
when exposed to high temperature, acidic conditions, which are
commonly associated with many foods. Sample biodegradable
eating utensils, composed primarily of polypropylene (73%), were
exposed to various food acids at high temperatures (~75-80 OC).
Using gas chromatography (GC-FID), the resulting solutions were
tested for possible leaching of the propylene monomer (C3H6) from
the exposed eating utensil. If propylene is to be found to in the
solution , then biodegradable eating utensils would be dangerous to
use for hot foods, as the propylene can be harmful if ingested.
Fortunately, it was found that none of the resulting solutions
contained any significant trace of propylene, and it can be concluded
that biodegradable eating utensils are safe to use for all foods.
Qualitatively Measuring the Safety of
Biodegradable Plastic Eating Utensils
Experimental Procedure
Preparation of Various Acidic
Solutions
Introduction
Biodegradable plastics have been more frequently used due to the
global concern for the environment and the popular, ongoing green
initiative. These plastics are designed to decompose in both aerobic
and anaerobic environments, meaning they can be composted or
placed in landfills for further degradation. They are metabolized by
microorganisms that can convert the plastic into a soil-like product
that is eco-friendly. Biodegradable eating utensils are either based
off of raw materials or petroleum, depending on the vendor.
10 mL of acetic, phosphoric, lactic, oxalic,
and citric acid were each added to 90 mL of
distilled water. 30 mL of each of these
aqueous solutions were added to 50 mL
beakers to be exposed to the biodegradable
eating utensils. A propylene standard was
created by dissolving 0.15 g of solid
polypropylene in 30 mL of hexane, which
was then centrifuged and placed in a gas
chromatography vial.
Utensil Exposure
One biodegradable plastic eating utensil
(~9.5 g, Taterware) was immersed in
each 30 mL acidic solution and then
heated for 45 minutes at 75-80 OC. The
solutions were then cooled to room
temperature and the plastic utensils were
removed from solution. The aqueous
solutions were then placed in gas
chromatography vials for analysis.
These findings are consistent with the safety claims that the
biodegradable plastic company, Taterware, makes for their
products on their website.
,
Image from Taterware
website:
Future research would involve examining other components of the
eating utensils, such as the potato starch. Other applications
would include advancing and optimizing the biodegradable process
of these plastic utensils to be composted and placed back into the
environment in a harmless manner. One area of research could
focus on reducing the amount of time these plastics need to be
digested by microorganisms. Another potential application would
be to develop safe eating utensils that can act as a fertilizer upon
quick decomposition in soil, as to pose no threat to ecosystems
and to improve soil quality.
Graph 4: Oxalic Acid
Retention Time of Peak Voltage (min)
1.288
Retention Time of Peak Voltage (min)
1.099
Peak Voltage (V)
10.89
Peak Voltage (V)
0.03
Peak Area (Counts)
2295006
Peak Area (Counts)
111869
References
1. Biodegradable Forks, Eating Utensils • Plastic Cutlery
ComposGraph ." BIODEGRADABLE Products, ComposGraph
GREEN Paper Products. N.p., n.d.
<http://greenpaperproducts.com/biodegradable-forks.aspx>.
2. "Gas Chromatography." CU Boulder Organic Chemistry
Undergraduate Courses. N.p., n.d.
<http://orgchem.colorado.edu/hndbksupport/GC/GC.html>.
Graph 2: Acetic Acid
Graph 5: Phosporic Acid
Retention Time of Peak Voltage (min)
1.433
Retention Time of Peak Voltage (min)
1.077
Peak Voltage (V)
0.33
Peak Voltage (V)
0.001
Peak Area (Counts)
730872
Peak Area (Counts)
75524
According to the propylene standard chromatogram (Graph 1), the
peak corresponding to the propylene monomer was found to be at a
retention time of 1.288 seconds, with an extremely high voltage of
10.89 volts. None of the tested aqueous acidic solutions showed a
peak that corresponded well to that of propylene, the closest acids
being acetic and citric acid with peaks at 1.433 and 1.359 seconds
respectively (Graphs 2 and 6). In addition, none of these peaks had
a voltage with any significant magnitude, all much less than 0.5
volts.
As far as observations, none of the biodegradable eating utensils
had a visual change after their exposure to the heated acidic
solutions. nor did they have any notable change in their overall
mass. They remained consistent with their creamy white color and
their shapes did not deform to any visible extent.
The fact that propylene was not found to leach into the acidic
solutions could be due to multiple factors. One would be the
physical properties of polypropylene. Since the utensils are
manufactured at temperatures much greater than that of which
foods are commonly served (~400 OF), they should have high
thermal resistance to leaching. In addition, polypropylene is a
string of nonpolar hydrocarbons that does not dissolve well in polar,
acidic solutions. Polypropylene is best dissolved in nonpolar
solvents, such as hexane, which are generally very uncommon
when speaking of conditions associated with foods. The
combination of these properties make biodegradable eating
utensils safe to use when consuming foods.
Data
Graph 1: Propylene Standard
Results and Observations
A 1079 injector type was used. The method
was set to 225 OC, with a run time of 3.39
minutes and a flow rate of 5 mL per minute. A
1 microliter injection of each solution was
placed into the gas chromatographer and gas
chromatograms were plotted, voltage versus
time. Each peak was noted and its retention
time was compared to the gas chromatogram
of the propylene standard, to determine if any
propylene is present in the solution.
According to the gas chromatograms of each of the aqueous acidic
solutions, no concrete detection of propylene was found. None of
the peaks were found to have a similar retention time to that of the
propylene standard. The observation that the physical properties
of the utensil did not visibly or significantly change after exposure
to the aqueous solutions agreed with these results.
www.earth-togo.com/taterware/faq
Perhaps one of the most common examples of biodegradable plastic
is in the form of eating utensils, which are molded from these plastics
and produced on a large scale. These utensils are also partially
made of potato starch. Schools and other facilities across the nation
are widely providing these utensils for people to use with their meals.
However, these utensils are used to eat foods that include extremely
high temperature soups, stews, chili, grilled meats, and other hot
prepared food. Due to the more fragile properties of these utensils, it
may be possible that people are possibly ingesting small amounts of
these plastics unknowingly, which could be a chronic health hazard
to many. Ingestion of propylene may disrupt the endocrine system,
and may lead to a range of cancers including prostate cancer. It is
important to know whether or not these utensils can withstand
common conditions associated with various foods may have, and to
ensure the health safety for all people using these utensils.
Concrete results of successful detection are made possible through
the use of GC-FID (Gas Chromatography - Flame Ionization
Detector). GC-FID works by anaerobically decomposing organic
solutions at high temperature to produce ions and electrons for
detection. The ions come from a hydrogen flame inside the gas
chromatographer, which then are detected using a positive and
negative electrode to create a potential difference, sensitive to mass
rather than concentration. The current induced by the ions hitting the
detector is measured versus time. Solutions of heated food acids
exposed to biodegradable eating utensils can be tested for propylene
by comparing their gas chromatograms to that of a propylene
standard, particularly retention times. By matching the peaks
exhibited by each solution, a qualitative conclusion to determine
whether or not propylene is present in a solution can be made.
Gas Chromatography- Flame
Ionization Detector (GC-FID)
Discussion and Conclusions
3. Tsuji, Hideto. Degradation of poly (lactide)--based biodegradable
materials . New York: Nova Science Publishers, 2008. Print.
4. "Twelve Principles of Green Chemistry | Green Chemistry | US
EPA." US Environmental Protection Agency. N.p., n.d.
Acknowledgements
Graph 3: Lactic Acid
We would like to give special thanks to our Graduate Student
Instructor, Aaron Harrison, for guiding us with our project and
answering any questions we had. We would also like to thank
Professor Jamie Cate for offering us suggestions on how to build on
our project idea.
Graph 6: Citric Acid
Retention Time of Peak Voltage (min)
1.083
Retention Time of Peak Voltage (min)
1.359
Peak Voltage (V)
0.13
Peak Voltage (V)
0.31
Peak Area (Counts)
598852
Peak Area (Counts)
40054
Special thanks is also given to Will Tooney and all the Chemistry 4
stockroom assistants, who helped supply all the materials required
for this project, and also for showing us how to use the lab
instruments for our data collection.