Abstract

Objective

For this science project, you will compare the absorptivity of different sorbents used for cleaning up an oil spill in water.

Introduction

Stop, look down, and wiggle your toes. Are you wearing shoes? If you are, chances are good that some part of those shoes is made from petroleum oil. Now look at the fabric of your clothes, your chair cushion, your bedspread, mattress, carpet, and drapes. Many of these fabrics were made from oil. Wander into the kitchen for a glass of milk or soda. The wax in that milk carton and materials in the soda bottle were made from oil. Open up the fridge and look at all the fruits and vegetables—those were grown with the help of fertilizers and pesticides, also oil-containing products. Check out your cupboards. All the packaging you see is made from oil, and the canned goods have additives made from oil, too.

Next, head to the bathroom and take a look at all the make-up, medicines, lotions, toothpaste, shampoos, and bandages made from oil. The laundry room also has oil-derived detergents to keep all those oil-made fabrics clean. And even the roof that keeps you dry needs oil to make it waterproof. Seems like everywhere you look around your home, from the ink in your pen to the CD’s in your player, you see something that was made from oil.

Oil products are everywhere, including the outdoors: car tires, roads, fuel that powers cars and ships, and heats homes. As you can tell, oil continues to be a very important product in our society, despite global warming fears.

Because oil is used in so many ways, great amounts of it are needed. It must be carried long distances to the factories and plants all over the world that use it to make the products that keep our society running. Every day, millions of barrels of oil are moved around, mostly on big ships, called oil tankers. Each tanker can carry more than 200,000 tons of oil.

Occasionally, these tankers have accidents—they hit other ships or scrape against rocks or ice and their hulls break open, spilling oil into the sea. One way environmental engineers try to clean up the oil spills before they kill wildlife and damage habitats is with sorbents—materials that are good at absorbing liquids. If you’ve ever used a sponge, paper towel, or kitty litter, you’ve used a sorbent. In this project, you’ll evaluate the absorptivity of common sorbents, many of which are currently used on a large scale to clean up real oil spills.

Terms, Concepts, and Questions to Start Background Research

• Petroleum oil
• Sorbent
• Absorptivity

Questions

• What characteristics make a good sorbent?
• Is a sorbent enough to clean up an oil spill?

Bibliography

• This source provides an overview of petroleum oil uses and oil spills:
  Absorbents Online. (n.d.). Oil Spill Basics. Oil Spill Intelligence Report. Arlington, MA. Retrieved March 6, 2008 from the AbsorbentsOnline website: http://www.absorbentsonline.com/oilspillbasics.htm
• This page on the Environmental Protection Agency website discusses the properties of oil that affect cleanup:
  EPA. (2008, March 3). Petroleum Oils. Retrieved March 31, 2008 from http://www.epa.gov/emergencies/content/learning/oilprops.htm

Materials and Equipment

• Newspaper
• Large plastic garbage bag
• Liquid measuring cup, 4-cup size; the angled, read-from-the-top types are easiest to use.
• Four or more sorbents that you want to test (3 cups of each)
  • Examples include: cotton, hair, fur, straw, coconut husks, corn cobs, corn husks, polypropylene pads, shop towels, and bird feathers. Barber shops or pet groomers are good places to get hair or fur. Shop towels and polypropylene pads can be purchased in the automotive section of many stores.
• Scissors, if sorbent needs to be cut into smaller pieces
• If you are using a coconut husk as one of your sorbents, you will need the following materials:
  • Gloves and eye protection
  • Hammer
  • Large towel or burlap bag
• Paper or glass bowls, 12-oz size (need three bowls for each sorbent you are testing)
• Vegetable oil (1 gallon)
• Pitcher of water
• Dry measuring cup, 1-cup size
• Single-serving mesh micro-screen coffee filter, should fit easily inside liquid measuring cup; available at stores that sell coffee supplies.
• Stopwatch
• Liquid soap
• Lab notebook
• Graph paper

Experimental Procedure

1. Spread newspaper onto your work surface, to make cleanup easier.
2. Open your garbage bag and put it close to the liquid measuring cup.
3. Prepare and test your sorbents one at a time so you can keep your workspace uncluttered. Large sorbents must be cut into small, thumbnail-sized pieced so that they can fill a measuring cup. Use caution when crushing or smashing coconut husks. Wear eye protection and gloves, and cover the coconut with a large towel or place it in a burlap bag before smashing it. Figure 1 shows examples of prepared sorbents.

   Figure 1. Four prepared sorbents (clockwise from top left): shop towels, coconut husk, hair, and cotton.

4. After you've prepared your first sorbent, divide it into three piles of 1 cup each and place each pile in a glass or paper bowl.
5. Make a data table in your lab notebook for each sorbent, as shown below for Sorbent 1, to record the results.

   Sorbent 1 Name (for example, Fur)	Total Water and Oil Level (A)	Remaining Water Level After Removing Sorbent (B)	Remaining Oil Level After Removing Sorbent (A-B)	Ratio = (Remaining Water) / (Remaining Oil)
   Trial 1 (using first cup of sorbent)
   Trial 2 (using second cup of sorbent)
   Trial 3 (using third cup of sorbent)

6. Pour 3 cups of water into the liquid measuring cup.
7. Slowly add 1 cup of oil. Do the oil and water separate or mix? Note: In some trials, a layer of bubbles may form between the water and oil layers. If this happens, then you must dump out the water and oil mixture and start with fresh ingredients since it will be too difficult to measure where one layer begins and the other ends. Alternatively, you can wait until the bubble layer disappears.
8. Put 1 cup of your first sorbent into the micro-screen filter. Lower it slowly into the water-oil mixture and gently move it from side to side for a few seconds until the sorbent is completely submerged, as shown in Figures 2 and 3.

   Figure 2. Testing hair as a sorbent.

   Figure 3. Testing coconut husk as a sorbent.

9. Start the stopwatch.
10. After 30 seconds, lift the filter with the contents of the sorbent inside and hold it just above the surface of the water-oil mixture for 30 more seconds to drain.
11. Dump the contents of the mesh strainer into the plastic garbage bag.
12. Get down level with the liquid measuring cup and read and record the total water and oil level (measure A, as shown in Figure 4).
13. Measure and record the remaining water level (measure B, as shown in Figure 4).

    Figure 4. Measure point A and point B after removing sorbent.

14. Wash out the micro-screen filter with soap and water.
15. Add water and oil until your measuring cup once again shows 3 cups of water and 1 cup of oil. Note: It is not necessary to start with fresh water and oil each time (steps 6 and 7) unless a layer of bubbles has formed between the water and oil layers.
16. Repeat steps 8–15 for the remaining piles of your first sorbent.
17. Then proceed with steps 4–15 for the rest of the sorbents you chose. Again, it is not necessary to perform steps 6 and 7 again, unless a layer of bubbles has formed between the water and oil layers.
18. Now calculate the remaining oil after removing the sorbent (A - B) for each trial and record it in your data table.
19. Calculate the ratio of remaining water to remaining oil for each of the trials and record it in your data table.
20. Average the ratios for each sorbent and record them in a new data table, as shown in the example below:

    Sorbent Name	Average Ratio of Water to Oil
    No Sorbent	3
    Fur
    Hair
    Straw
    Cotton
    Corn Husk
    Coconut Husk
    Polypropylene Pads

21. Plot average water-to-oil ratios (y-axis) vs. sorbents (x-axis). The higher the ratio, the better the sorbent was at removing oil. Are any sorbents less than the starting ratio of 3? This means that the sorbent absorbed more water than oil and would not be a good candidate for cleaning up oil spills. Which sorbent has the highest average water-to-oil ratio?

Variations

• The project above showed which sorbent was the best by volume. Which sorbent is the best by weight?
• Which sorbent is the best by time?
• Does shape impact absorptivity? For the same weight, what happens when you twist or roll a sorbent tightly? What if you leave it in big pieces or chop it up?

• For more science project ideas in this area of science, see Environmental Engineering Project Ideas.

Credits

Kristin Strong, Science Buddies

Last edit date: 2008-04-09 14:00:00