Summary Assessment Report
Experiment: Liquid CO2 Extraction of D-limonene from Orange Peel
Background: This laboratory exercise was evaluated as part of the design of a hands-on
workshop entitled Implementing Green Chemistry in the Laboratory for the Biannual Conference
on Chemical Education delivered on Tuesday, July 29, 2008
Workshop design focused on selecting a core of six laboratory exercises that could be
implemented in a variety of learning contexts (general, organic, non-majors etc.) and be
adapted to a “cooking show” format. This format was developed so that participants could set up
the reactions and then work with previously prepared materials to complete the laboratory
experience within 30 minutes.
During the final phase of development, three undergraduate chemistry students from Gordon
College tested and optimized the revised laboratory procedures for the workshop during spring
semester 2008. This work was completed as part of a Green Organic Literacy Forum (GOLuM)
project associated with their sophomore organic chemistry course taught by Professor Irv Levy
at Gordon College.
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Bethany Corcoran, Gordon College
Zackary Schwamb, Gordon College
Christopher Tanga, Gordon College
This BCCE workshop was collaboratively designed, tested, and delivered by members of the
Green Chemistry Education Network (GCEdNet) and undergraduate chemistry students at
Gordon College. The Green Chemistry Education Network (GCEdNet) serves as a catalyst for
integrating green chemistry in chemical education at all levels. As a network of educators, we
support opportunities to research, develop, implement and disseminate green educational
materials. The GCEdNet reaches out to all chemistry educators through collaborating and
mentoring, facilitating professional growth, and fostering the synergistic integration of green
chemistry in education.
Continued on the next page Liquid CO2 Extraction of D-limonene from Orange Peel
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Experiment: Liquid CO2 Extraction of D-limonene from Orange Peel
Reviewed by: Bethany Corcoran, organic chemistry student at Gordon College and submitted to
GEMs May 2008.
Assessment Summary (number of replications = 2; also performed in class with 4 groups of 5+
participants)
Answer the following on a scale of 1-5 where 1 is strongly disagree and 5 is strongly agree.
Lowest to Highest
As I prepared the method, it was very clear:
1 2 3 4 5
The method worked as expected when I performed it:
1 2 3 4 5
The method worked as expected when I ran it for someone else:
1 2 3 4 5
This is a useful way to introduce principles of green chemistry:
1 2 3 4 5
The estimated time was consistent each time I performed it:
1 2 3 4 5
Cost of starting materials:
15 oranges: $10.00
Roll of wax paper: $3.00
To this list I would also add:
10 lb. Dry ice (if not provided by the host institution): $5.00/lb = $50.00
Safety concerns: Although there is a concern for covers blowing off tubes, this has not yet
happened during my tests of the procedure or during any other demonstration with Gordon
College students. For safety sake, do not stand over the cylinder while the tube is in the water,
and handle dry ice carefully. Previous safety notes are accurate to suggest wearing safety
goggles and gloves, and to not repeat the procedure more than 5 times with the same
centrifuge tube. The final requirement is to refrain from using glass cylinders or centrifuge
tubes.
Quantity of hazards and waste: There are no hazardous products involved, expect for the dry
ice. This should be kept in a cooler, and extras can be dissolved in water. Orange peels can be
thrown away, and water dumped down the sink. The product, D-Limonene, can be saved in a
vial or disposed in the trash.
Special equipment/materials needed: A hot plate and source of electricity are needed for
repeats of the demonstration. Also, dry ice must either be purchased or made on location. If
purchased, a cooler and gloves are necessary for storage, and would ideally be purchased the
day of the presentation. Similarly, if the host institution has a dry ice machine and CO2 source,
then it should be made the day of the presentation and store in the cooler.
Continued on the next page Liquid CO2 Extraction of D-limonene from Orange Peel
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Additional comments: The procedure was best described in “Part 2,” the version of the
experiment which is used in the Simmons College Organic Chemistry labs. The procedure is
most productive with five replications of the extraction (the most that can be expected of one
centrifuge tube), and with 2.0g of starting orange rind. For demonstration purposes, the orange
rind should be grated, weighed, and in the centrifuge tube before hand, so as to allow the time
for each replication. The presenter should have a previously isolated example of the Dlimonene product as well as a print-out of its IR spectra. In order to move quickly, the water
must remain warm around 60C. If this is not possible, then each replication will be slower, and
30 minutes may not be enough time to reach a visible product.
Both tests were performed with slightly different wire traps. Rather than using a wire mesh, the
trap was a tightly coiled copper wire cylinder to the diameter of the centrifuge tube, with a piece
of inserted filter paper of the same size.
The most important suggestion, as previously noted in the Part 2 procedure, is to restrain from
packing either the orange rind or the dry ice. Isolation of the product is only possible with a
loosened orange rind. This procedure is a good example of green chemistry, as long as the
connection has been explained beforehand.
Liquid CO2 Extraction of D-limonene from Orange Peel (tested procedure)
Materials:
• gloves
• goggles
• orange
• zester or grater
• wax paper
• spatula
• forceps
• 5x15mL polypropylene centrifuge tubes with caps
• Solid copper wire trap (flat coiled copper wire with right angle perpendicular “handle” )
• 1 transparent polycarbonate plastic cylinder on base
• Small hot plate
• 600ml beaker
• Thermometer
• Analytical balance
• 1lb crushed dry ice in container
Procedure
1. keep orange at room temperature
2. lay out wax paper
3. grate orange portion of rind with 2nd smallest size on grater (long strips, not pulp)
4. form wire trap
5. record mass of empty centrifuge tube
6. insert wire trap into the centrifuge tube
7. record mass of centrifuge tube and wire trap
8. add orange rind to centrifuge tube (to 7 or 7.5mL mark) DO NOT PACK TIGHTLY
9. record mass of centrifuge tube, wire trap, and orange rind
Continued on the next page Liquid CO2 Extraction of D-limonene from Orange Peel
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10. crush dry ice with hammer or mallet
11. fill 600mL beaker with water
12. heat water to 60C
13. pour heated water into polycarbonate plastic cylinder
14. fill centrifuge tube with dry ice (on top of orange rinds)
15. tap the tip on the table to settle
16. continue filling till settle and full
17. twist on cap tightly (discard if does not stay twisted)
18. immediately drop capped centrifuge tube into the cylinder of water (point down)
19. watch from the side of the cylinder, not above
20. observe for 15 seconds
21. liquid CO2 should form after 15 seconds
22. if no liquid forms after 1 minute:
• remove carefully from water
• tighten cap
• replace in water
• or if still does not liquefy:
• empty dry ice
• refill with new dry ice, following methods
23. if liquid does form:
• will pass through the peel
• liquid will boil for about 2 minutes, 45 seconds
• do not remove from the water while liquid is boiling
• oil collects in the bottom of the tube or with peel
24. when liquid has evaporated, remove tube from the water with forceps
25. open cap to tube slowly and away from face
26. look for pale yellow oil in the bottom
27. break up orange rind with wire
28. repeat with more dry ice four times
29. again look for pale yellow oil
30. after 5 runs, remove trap from the tube (orange rind should come with)
31. remove any other solid from the tube with a spatula
32. dry outside of tube with paper towel
33. record mass of centrifuge tube and product
34. calculate original mass of orange rind
35. calculate final mass of produce
36. calculate percent recovery based on mass of starting orange rind and final product
Continued on the next page Liquid CO2 Extraction of D-limonene from Orange Peel
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(4/10/08) Independent lab notes (following the above procedure)
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Prepared the dry ice from the CO2 canister and dry ice machine in the Physical
Chemistry lab (filled 100mL beaker)
Heated 600mL of water on hot plate
Weighed one empty centrifuge tube: 6.89g
Made the wire trap by coiling a cylinder (1/4 in. long) of copper wire to the diameter of
the tube (1.5cm) and pulled a perpendicular handle. Inserted filter paper through he
coils to function as trap. Slid wire and filter trap into the centrifuge tube.
Grated (into little strips) the orange rind of one orange onto wax paper.
Weighed 2.0 grams of orange rind, poured into centrifuge tube on top of trap. (Did not
pack: filled to the 7mL mark)
Poured hot water (60C) into 250 mL polycarbonate graduated cylinder, to the 200 mL
mark.
Filled the remainder of tube with crumbs of dry ice, lightly tapping the tube to settle.
Tightly capped and immediately dropped point first into the hot water.
20 seconds later the dry ice of the centrifuge tube began to melt.
15 seconds later the tube began to spin.
75 seconds later the CO2 had completely melted.
Removed the centrifuge tube from the water, uncapped, and loosened orange rind with
forceps.
Observed moisture in the bottom, as potential product.
Checked the temperature of the hot water
Repeated the filling of the centrifuge tube with dry ice, capped, and dropped again into
the warm water.
Repeated 4 times (rechecking water and loosening orange rind each time)
After 5th extraction, removed the orange rind and trap, dried the centrifuge tube with
paper towel and took the mass (6.94g) of tube and product.
Very small beads of light orange product in the tip of tube
Calculated the mass of the product: (mass of tube and product)-(mass of empty tube)=
(6.94g) – (6.89g) = 0.05g
Calculated percent recovery: (mass of product)/(mass of orange rind) x 100 =
(0.05g)/(2.0g) x100 = 2.5 % recovery
Continued on the next page Liquid CO2 Extraction of D-limonene from Orange Peel
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Liquid CO2 Extraction of D-limonene from Orange Peel
(4/21/08) In class participation notes
The group had prepared 2.5g of orange rind on wax paper before the demonstration. They had
also collected all materials including a cooler of dry ice and heating plate with hot water. Wire
traps had also been made before hand, by the same method as I had used in the lab.
Each group of 7-10 students were expected to weigh the empty centrifuge tube, insert new filter
paper into the wire trap, take the mass of the tube and the trap, fill the tube with 2.5g orange
rind, and then reweigh. On top of the orange rind the groups spooned dry ice, packing tightly
until full. The lids were tightly screwed on, and the polycarbonate cylinder was filled ¾ full of
warm water (unspecified temperature). After dropping the CO2 centrifuge tube into the water,
the dry ice remained solid, even after a minute.
The tube was then removed, and the dry ice removed. The orange rinds were then loosened up
with a spatula and more dry ice was added to the top, tapping the tip of the tube on the table
after each addition. After (by about 30 seconds) recapping and placing back in the warm water,
the CO2 slowly started to melt. (At this point, some group members began adding dry ice directly
to the hot water, for visual effect. Although entertaining, this cooled the water dramatically. The
tube started to spin within the water. All of the CO2 seemed to have melted within 1.5 minutes.
A minute later the tube was removed from the water, uncapped. No product was visible at the
bottom.
For a second run, replacement water was heated. More dry ice was carefully added on top of
the orange rind to the centrifuge tube, which was then tightly recapped and placed back into the
hot water.
The procedure was not repeated multiple times, and so the orange rind and trap were removed
from the tube. Very little, if any, product was visible in the bottom of the tube. Some orange rind
pieces had been washed to the bottom. In taking the mass of the centrifuge tube and product,
there was no distinguishable product.
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