Scientists Develop New “Sponge” to Clean Up Oil Spills

Americans watched in dismay at the recent oil spill in the Gulf of Mexico that contaminated hundreds of miles of shoreline. The fundamental problem is that oil is hydrophobic. This means that the oil molecules don’t like to associate with water molecules; the electronics are wrong, and it’s unfavorable for the two compounds to come into close contact. So, trying to remove oil from water is difficult, as the oil tends to form small droplets and slicks which can be difficult to remove from a large quantify of water, as was the case in the Gulf of Mexico Spill.

Luckily, chemists have a large amount of experience manipulating hydrophobic molecules. They can alter the degree to which a molecule “likes” or “dislikes” water by using chemical reactions to add on particular fragments to a molecule. This was the technique used by scientists at the University of North Texas. They designed frameworks consisting of both metals (silver) and organics, as well as fluorinated sections, called collectively a fluorous metal organic framework, or fluorous MOF. The fluorine atoms formed a rim around the surface of the molecule and made them hydrophobic, as fluorine – like oil – doesn’t like to associate or interact with water. Because of the star-shaped design of the molecule, the combination of the silver ions and the fluorine atoms provide a capillary action.

The oil contaminant is drawn into the center of the trifluoromethyl-bearing triazolate ligands, where they remain suspended. The exterior rim of the fluorine atoms repels water and so the oil droplets become stabilized. It’s an amazing demonstration of a more general phenomenon that scientists call electonegativity. The fluorine atoms are both hydrophobic (water hating) and olelophobic (oil hating); they don’t get along with anyone but themselves. This unique quality among the elements makes fluorine the perfect choice to decorate this oil sponges. Once the oil has been absorbed, the metal organic frameworks can be extracted into a fluorinated solvent which will then separate into different layers of oil and the fluorinated silver-containing ring. This research is clever and makes innovative use of fluorine, an element that most chemists would rather avoid due to its tendency not to mix with anything – but that’s the key to success of this approach.

People also view

Leave a Reply

Your email address will not be published. Required fields are marked *