Cleaning Up the Oil Spill
The oil spill in the Gulf of Mexico started April 10th and is leaking an estimated 500 gallons a day. Until very recently, the reports about the containment and clean up have not been encouraging. As we watch and listen to the reports of the clean up, we can easily see the science behind some of the efforts that are being used to clean up the mess.
A lot of the clean up is based on a basic scientific concept that we all know: oil and water don’t mix. Have you ever reached in your fridge for the salad dressing, only to notice that the oil and vinegar are completely separated? A good article on buzzle.com explains how this happens:
“Both oil and water are liquids, but their chemical compositions are very different from each other. Oil is made of long non polar hydrocarbons, which means that they experience weak forces of attraction. On the other hand, water molecules are dipolar, which means that one of their ends is positively charged while the other is negatively charged. Also, oil molecules are much bigger than water molecules. The mixing of any two liquids is attributed to the similar nature of their molecules. The difference in the molecular structures of oil and water is one of the main reasons why they do not mix with each other. Another important factor is surface tension. When water molecules come together, they form a network of hydrogen bonds which results in a very high surface tension. Both oil and water have high surface tensions, due to which the adhesion between them is weak and they do not mix. Why are patches of oil floating on water circular in shape? It’s because of surface tension. The oil molecules cling to each other to form an elastic layer with the minimum possible surface area.
For two liquids to mix, the chemical bonds holding the molecules together, need to be broken and new ones need to be formed. The bonds between water molecules are very strong, whereas, the bonds between oil molecules are weak. Hence, a lot of energy needs to be consumed in an effort to bring the water and oil molecules together.”
These principles are what is behind the clean up efforts because as oil leaks out of the gusher on the seafloor, it rises to the surface and forms a layer on top of the water. One way that the clean up crews are trying to remove the oil is skimming the oil off the surface; they drag a long inflatable line behind a boat to collect the oil and then scoop it up. In addition, the amount of oil can be reduced through “in-situ burning”. (“In situ” means “in the place” in Latin.) In-situ burning takes advantage of the fact that oil is highly combustible, which means that it can easily catch fire. Different kinds of oil have different flashpoints – the lowest temperature that the substance can be to catch fire.
The National Oceanic and Atmospheric Administration has very detailed information on its website about in-situ burning.
Another option for removing the oil off the Gulf waters is through “dispersants.” These are chemicals that attach to the oil and help it break up into small droplets; this which speeds up the natural dilution. Clean up crews apply these dispersants by boat, helicopter, or airplane. Here are some more details about how this works.
To see other ways that BP’s scientists are cleaning up the oil spill, check out BP’s Gulf of Mexico response website.
