Can oil be completely removed from seawater using conventional methods? A science experiment by Jacob Docalavich
The Problem: Oil spills such as the Exxon Valdez in Alaska have a devastating effect on the environment. Unfortunately, although billions of dollars have been invested in technology to obtain oil, very little new technology exists to clean up oil that is spilled in the ocean. In fact, oil still remains in Prince William Sound, where the Exxon Valdez crashed, even though the spill happened in 1989, 9 years before I was born. The effects of the oil can still be seen today.
“March 24, 1989, the supertanker Exxon Valdez ran aground on Bligh Reef in Prince William Sound on Alaska's southern coast. Some 10.8 million gallons (40,900 kiloliters) of oil spilled from the deep gash in the ship's hull, eventually washing up on more than 1,200 miles (1,900 kilometers) of pristine coastline, causing what still stands as the worst oil spill in U.S. history. The impact on local wildlife was devastating: An estimated 250,000 seabirds died in the months after the spill, and 14 members of the 36 local Prince William Sound killer whale pod had disappeared by 1990. The so-called carcass count also tallied, among other creatures, 1,000 dead sea otters as well as 151 dead bald eagles, according to the Exxon Valdez Oil Spill Trustee Council (EVOSTC), a group formed to oversee restoration projects. Some of the spill remains to this day, with a 2003 estimate pointing to about 20,000 gallons (75,700 liters) soaked deep into sands in intertidal zones, slowly poisoning ducks and other shore creatures.” Scientific American, March 23, 2009
My Hypothesis: Oil cannot be completely cleaned from seawater even in small quantities.
My Procedure: Most technology used to clean up oil spills in open water (containment, absorbents, detergents, enzyme treatment) can easily be replicated at home. We will not attempt burning the oil off for safety reasons. I intend to recreate an oil tanker spill on a small scale, and evaluate the effectiveness of several different methods as individual variables in removing the oil. I will record the data by photographing the entire process and use the photos to demonstrate my progress in the cleanup. If this technology can be relied upon to clean the entire ocean, they should be effective in cleaning motor oil out of a baby swimming pool.
Materials 20 gallon inflatable swimming pool for infants. 1 quart heavy duty motor oil (the closest I can get to crude oil.) A plastic boat (my tanker.) Sand Sea grass 20 gallons tap water with salt added to simulate seawater. Dawn dish detergent (contains a surfactant used by oil companies to clean up oil spills) SHOUT laundry stain remover (enzyme based oil remover) Floating bumper to help contain oil floating on the water. 800 cotton balls Measuring cup Digital Camera
My simulated oceanComplete with beach, marshland (represented by grass), and built on top of our hot tub. We turned the motor on to simulate waves.
The small amount of oil spread quickly to cover most of the water’s surface.
Step 1: Containment The oil spread too quickly for the floating bumper I made to contain it.
Step 2: AbsorbentsI tried to absorb the oil with cotton, each cotton ball weighed approx. 1oz. Although only 8oz. of oil were spilled a large amount of oil remained visible on the surface of the water, even after 400 cotton balls.
Step 3: Dispersants Dawn has a surfactant used to break up the oil. It initially made the water very cloudy.
The oil broke up into small particles, but moved again to cover the surface of the water, this time in a greasy cloud.
SHOUT laundry stain remover contains an enzyme used to break down oil in the ocean. When we added this to the cloudy film that resulted from the Dawn, the oil clumped back together in large blobs.
Following the enzyme treatment, I scooped out as many of the blobs of oil as I could easily see with a sandbox shovel. I then decided to wait a day to see if smaller particles would merge together again and if more oil would rise to the surface out of the sand. This is what I found. A photo of what is washing ashore from the recent disaster in the Gulf of Mexico. My Model
Again, I removed the visible oil by scooping it out. I waited another 5 days to see what would happen. The sea grass I planted in the sand began to die, and plenty of oil was still visible on the water’s surface.
Conclusions: My hypothesis was correct. I found it impossible to completely clean the water even with all the different techniques I used. Ounce for ounce, I used 50 times as much cotton as there was oil and my best estimate based on the visible oil was that I absorbed less than half. The oil was very difficult to remove.
Conclusions: (continued) The chemical additives did little to decrease the amount of oil in the water, although adding the enzymes did seem to make it easier to remove. No one technique, nor repeated attempts over time enabled me to completely clean the water, even to the naked eye. Even if I had removed all of the visible oil, I have no doubt that I could have found oil particles if I had studied the water under a microscope.
My spill was done on a very small scale. It is scary how ineffective I was at cleaning up just 8oz. of oil. I can conclude that cleaning up the ocean would be far harder.
I would have liked to evaluate burning off the oil, but safety concerns (and my mom) prevented this!
It only took 6 days for my plants to begin to die as a result of the oil. It is easy to conclude that the effects of a large spill on plant and wildlife would be catastrophic.
Results: Every effort should be made to avoid oil spills. They are nearly impossible to clean up, and have devastating effects on the delicate ecosystems of coastal regions. After this experiment I am worried about the effects of oil on the beaches where I live.
Bibliography: American Scientific, March 2009 Photos courtesy of the following: The Boston Globe www.hotindienews.com Popular Science