MadSci Network: Chemistry

Re: What is the chemical composition of Corexit 9527?

Date: Fri Sep 7 16:54:15 2001
Posted By: Chris Kaiser, Process Engineer, Anvil Corporation
Area of science: Chemistry
ID: 999632641.Ch

Hi, Eric.

Let me say first that I think it is great that you have chosen to do your project on ways to remove crude oil when spilled. Nobody likes oil spills, and some people think that the fact they happen is reason enough for us to stop producing crude oil. However, people like you realize that our society needs oil to operate and that we should direct our efforts to cleaning up the inevitable spills as completely, quickly, and inexpensively as possible.

Corexit 9527 is a dispersant - it is used to make an oil spill go from a consolidated slick sitting on the water's surface to lots of little tiny droplets mixed with through the entire water column. In this way, a situation which can cause a lot of damage to the environment and to wildlife (the oil slick) is changed into a situation where the oil can do little damage, since it is now diluted to a large degree in the water. Dispersants allow the oil to be broken up into small droplets by providing a means for the oil and the water to mix. The important thing to remember here is the principle of "like dissolves like." Polar molecules will mix with polar solvents (like water), while nonpolar molecules will only mix with nonpolar solvents (like crude oil). Dispersants are made of complex molecules which have a polar region and a nonpolar region. This means that one end of the molecule will dissolve in the crude oil while the other end dissolves in the water. As energy provided by the wind and waves mixes the dispersant chemical with the oil slick, the dispersant molecules surround individual droplets of oil, allowing them to mix with the water. This series of pages, from the National Oceanic and Atmospheric Administration, explains dispersants in more detail.

As shown on this page (Physical Properties section), the active ingredients of Corexit 9527 are confidential. However, the Ingredients/Identity section of the Material Safety Data Sheet (MSDS) for this product purports to show all the ingredients, not listing any of them as proprietary. On the other hand, the names of some of the ingredients, such as "Butyl Cellosolve," do not follow standard organic chemistry nomenclature rules, so they may as well be proprietary. Given this, I'm afraid I can't tell you what the actual active ingredients of Corexit are. Hopefully, the description above of how the product works is enough for you to go on.

Dispersants are not the only way of removing oil spills. For some spills (particularly small spills and those that occur far from shore), natural forces such as volatilization (evaporation of lighter components of the oil), settling of the heavier components to the bottom, and breakup and dispersal of the slick by wave action alone can be relied upon to remove the oil slick from the water's surface. In addition, some slicks can be contained within booms and vacuumed up with skimmers. Some spills are responsive to bacteria which can be applied to the slick to digest the oil. Finally, some oil slicks can be burned directly on the water's surface.

I hope this helps. Good luck on your project.

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