Monday, January 14, 2008
Ionic liquids: Model for future chemical design
Just had to point out that a paper which I'm a co-author on came out today:
Aquatic toxicity and biodegradation of ionic liquids: A synthesis.
The first author is Konrad Kulacki, and he's certain the guy who put in the most work on this actual paper, but the paper is a review/synthesis of an entire group's research on the effects of ionic liquids on aquatic ecosystems.
So what are ionic liquids?
Ionic liquids (ILs) are essentially organic salts that happen to be liquid at room temperature. There's been a lot of research into ILs, because they seem to be able to perform all kinds of industrial functions that are currently performed by volatile organic compounds (VOCs). VOCs work great, but they are also a huge health risk to workers and the environment because they evaporate. Most ILs do not evaporate at all and therefore switching from VOCs to ILs will reduce air pollution.
And that is fantastic. The downside is that many of the ILs being developed for industry are extremely water-soluble. That means they are going to end up in water-ways. So a group of ecologists at the University of Notre Dame (lead by Gary Lamberti and Charles Kulpa) teamed
up with some chemical engineers and civil engineers (also from Notre Dame and lead by Joan Brennecke) to see if ILs could be developed that had minimal impacts on the aquatic environment. As it turns out, there are literally billions of different possible ILs, and so designing ones that aren't harmful to the environment should be possible.
While the research on environmental effects has failed to keep pace with the research on the usefulness of ILs, a significant amount of data has now been gathered. From studying a small number of ILs spanning a wide range of possible IL properties, we've been able to isolate some traits that seem important in terms of toxicity and biodegradation (i.e., alkyl chain length). We've also been able to get a feel for how different taxa will respond to ILs. For instance, duckweed seem to be more sensitive than algae. Fish and snails seem to be less sensitive than Daphnia. All of this information can help us figure out why ILs cause toxic effects, what ecosystems and biota are most at-risk, and what can be done to mitigate any harm.
The Notre Dame IL research group (which put me through grad school) isn't the only research group working on the environmental impacts of ILs. A group out of Germany (I think) is also hard at work on the same subject. They've actually published a series of papers exploring the idea of incorporating environmental effects into the design phase of chemical development (you can see their list of pubs here, the ones in Green Chemistry are particular interesting). What both groups (and numerous others) are really interested in is finding ways to design more environmentally benign chemicals that are also able to perform in industrial applications. This same approach is being somewhat adopted for nano-materials.
I could go on and on about the IL story, and maybe I will at some point in the future. Today I just wanted to celebrate a new publication.