Posts Tagged dispersant

Corexit Alternatives

Posted by on Sunday, 15 August, 2010

After the spill in the Gulf, British Petroleum used Corexit to disperse the oil in the ocean. Corexit is harmful to sea life, so many people protest the use of this compound. BP claims that Corexit is the safest dispersant it can use. So I decided to see if I could find any alternatives to Corexit. There are safer dispersants available, but they do not have EPA approval, although they have approval in Europe.

The IVL Swedish Environmental Research Institute provides a list of 25 chemical dispersants which various countries authorize for use cleaning up oil spills. The two dispersants which have seen widespread use in the Gulf of Mexico, Corexit 9500 and Corexit 9527, receive approval in several countries, while other dispersants have less widespread authorization. Two other versions of Corexit, Corexit 9550 and Corexit CRX-8, are only approved for use in Canada as of 2001.

Dispersants do vary in toxicity. A list compiled by Cornell University includes a study which compares the toxic effects of several dispersants on corals. The study concludes that Slickgone, which is approved for use in Norway and Great Britain, has the least effect on coral. In ascending toxicity, the other dispersants in the study are Petrotech, Inipol and Bioreico, Emulgel, and Dispolene. Inipol and Dispolene are approved for use in several counries according to the IVL, and the other dispersants are not mentioned on the list.

A visit to Dasic shows that the company is aware of problems with dispersant toxicity and has designed its dispersants to address these issues. Of the two Dasic Slickgones on the IVL list, Dasic claims it did not maintain approval in Britain for Slickgone LTSW, and still has British approval for Slickgone NS. Dasic mentions that it also makes Slickgone EW, a newer product version. Of note, there is also a freshwater version of Dasic Slickgone, which is important in case the oil spreads up the Missisippi. Dasic mentions that freshwater dispersants are less commonly available. According to the Bonn Agreement, Belgium also uses Slickgone NS.

BP does have stocks of Slickgone. According to the Epoch Times, BP has ordered 150 metric tons of Dasic Slickgone, and claims that it hasn’t been delivered yet because it doesn’t have EPA approval. The IVL Swedish Environmental Research Institute list does not show that Dasic Slickgone is approved for use in either the USA or Canada. EPA approved dispersants appear on the National Contingency Plan Product Schedule, along with surface washing agents and bioremediation agents which the EPA has approved. The Epoch Times article also mentions that Norway does not allow the use of Corexit 9500 in the North Sea because it is considered to be too toxic.

Oil Spill Dispersant Information

Posted by on Saturday, 29 May, 2010

BP is using dispersants to mitigate the effects of the oil spill in the Gulf of Mexico. A dispersant breaks up large patches of oil on the surface and forces them to sink into the ocean. Some dispersants are toxic, some are less toxic. The dispersant BP is using is called Corexit. According to the MSDS, it is a hydrocarbon with several other additives. Nalco, the manufacturer, does not give the exact formulation of Corexit, likely because it is a trade secret. This makes it very difficult to determine the toxicity of this dispersant.

Searching for more information on the formulation gives some information on the typical components of a dispersant. The National Academy of Sciences mentions some of the chemicals which make up a surfactant. There are ionic and nonionic chemicals present in the surfactant. Nonionic surfactants that are in Corexit surfactants include sorbitan oleates and their derivatives. Sorbitan oleate is an emulsifier and an oil soluble surfactant. Derivatives include several chemicals known as tweens, such as Tween 80. Tween 80 itself is safe enough to be used as a food ingredient, but manufacturing it requires the use of the precursor ethylene oxide, which is a carcinogen and might be present as an impurity. Tween 80 is also known as polysorbate 80. This substance includes very long chain hydrocarbons, so it is related to fats and oils and it is soluble in petroleum. According to the National Academy of Sciences, the chemical sodium dioctyl sulfosuccinate is the main ionic surfactant. It is also considered safe for use in food as a cocoa additive, according to Ohio State.

Scientists at the University of California, Davis specifically tested one type of Corexit, Corexit 9500, to determine its toxicity for sea life. UC Davis is a large university in Davis, a town outside California’s capital, Sacramento. This school has a great reputation for research, and it is one of the best ranked universities in California. Davis focuses heavily on agricultural research because of its inland location near a lot of farmland around the state capital. The main conclusion from this study is that the different formulations of Corexit had similar toxicities. Corexit 9500 is designed to be less toxic than the previous formula, Corexit 9527. According to the National Academies the Corexit solvent was changed from glycol ether, which was irritating people, to a variety of long chain hydrocarbons, basically chains longer than octane like nonane and decane, up to hexadecane where anything with a longer chain isn’t liquid at room temperature anymore and behaves more like a wax.

Corexit appears to have irritant effects on humans from what I’ve seen so far, although many individual components are safe. It does seem like it can interfere with the respiration of sea life according to the UC Davis study. The oil spill itself is going to kill a lot more sea animals than the dispersant will. There is an alternative, Dispersit, which is designed to create less problems than Corexit. According to Elon University, a study on Dispersit shows that it is harmful to brine shrimp.