Wednesday, September 30, 2015

Microbeads as a Solution to Pollution?

(Thanks goes to Eric F. Brown for bringing this article to my attention.)

This might not be turning lemons into lemonade, but it could be close. Microbeads have recently become the cause de du jour for environmentalists fighting plastics in the oceans and other bodies of water, but a UC Santa Barbara researcher looks upon the beads as a solution and not a problem. By putting a carefully selected peptoid [*] coating on the beads, the beads can bind hexavalent chromium and remove it from water. Hexavalent chromium is the particularly nasty version of the metal made famous by the movie Erin Brockovich and is in the drinking water of cities as large as Chicago.

While hexavalent chromium ions are a worthwhile and newsworthy target, I imagine the technique could be applied to recovering other ions/elements as well. Arsenic is a problem in many parts of the world as are other metal/metal ions. And I can't see any reason why any particular bead wouldn't be able to recover multiple metals (although a mixture of beads targeting each individual metal could work too).

The article raises but doesn't answer the question of recovering the beads. Making the beads around a magnetic core would be a quick-and-easy option to allow for recovery, but buoyancy would be a concern. Smaller cores would help that, but then a stronger recovery magnet would be needed. Increasing the thickness of the polymeric shell would increase the buoyancy, particularly if it was foamed to any degree. But even if the whole concept of using microbeads fails, the peptoid coatings could still be used to coat other materials to reach the same end. Peptoids are apparently quite resistant to hydrolysis, which is crucial for application like this, so it's just a matter of finding an acceptable substrate with a large surface area and possibly sufficient porosity so that this doesn't end up as a giant filter removing the good (sea life from microbes on up to whales) as well as the bad.

[*] Peptoids are like peptides, oligomers of amino acids, but amino acids have their substituents on the α-carbon, while for peptoids, the substituents are on the nitrogen.

Previous Years

September 30, 2014 - A Mixing Demonstration using non-Newtonian Blue Maize Flour Suspension

September 30, 2011 - Now that we have the "Perfect Plastic", you don't need me

September 30, 2011 - The Research behind "The Perfect Polymer"

September 30, 2010 - Pyridine


Anonymous said...

Shouldn't it be "du jour" rather than "de jour"?

John said...

@anonymous: My high school French teacher would be so upset...that is, if I had had a high school French teacher. I took German, and the only French I have picked up is through my engineering education (Carnot, Fourier, Laplace, Biot, Pascal, Poisson, L'Hopital...) and whatever I can pick up from the containers of consumer products designed for sale in the US and Canada.

Your comment has been appreciated and a correction has been made. Thank you.

Anonymous said...

I didn't want to be pedantic; only for the higher sake of accuracy, which we're both devoted to. Good luck for your new role as a teacher.