Top Papers in Environmental Technology, First Runner-Up: Single-walled nanotubes in a tight spot
COURTESY OF MENACHEM ELIMELECH
University. O’Melia focuses on parThe researchers found that the “Transport of Single-Walled Carticle interactions and interactions long tubes would disperse, only bon Nanotubes in Porous Media: at nanoscale surfaces. Elimelech to cling to sand particles in the Filtration Mechanisms and Returned to nanomaterials several right salty settingsor be caught versibility” by Deb P. Jaisi, Navid years ago, in what seemed to be a in pore spaces too tight to let B. Saleh, Ruth E. Blake, and Melogical continuumsfrom colloids to them pass. nachem Elimelech, Yale Univernanoparticlessto study sity, 2008, 42 (22), such small-scale mechan8317-8323; DOI ics and processes. Jaisi 10.1021/es801641v. says he joined Elimelech’s Imagine trying to group at Yale as an Interthread a pencil through departmental Bateman the spaces of a room Postdoctoral Fellow and is packed tightly with bascoadvised by Ruth Blake ketballs. That’s almost of the Department of Gewhat it would be like to ology and Geophysics. squeeze a single-walled Elimelech and his group nanotube through the are among the first to repores of typical sandy port on some of the possediment, says Mesible fate-and-transport nachem Elimelech of issues related to nanomaYale University. terials and on their potenThat realization is also tial environmental risks one of the major findand hazards (DOI ings in one of ES&T ’s 10.1021/es8006904). One best papers of 2008, in Menachem Elimelech (center, top row) and postdoctoral which Elimelech and his researcher Deb Jaisi (center, bottom row) of Yale University led previous finding from the group showed that colleagues examined the a team of researchers in tracking the behavior of SWNTs in SWNTs are very toxic to mechanisms that would idealized soils in the lab. The next step is to see what happens bacteria. affect single-walled car- in the real world. This latest paper from bon nanotubes, or the team illustrates “the technologThe more salt, the more the SWNTs, belowground and if they ical prowess that is necessary to get SWNTs stuck, they found. Howcould reach groundwater. this fundamental information,” ever, the SWNTs could be washed “Take any other nanoparticles says Miriam Diamond of the Uniaway in less-ionic water. Lessand you will find typical aggregaversity of Toronto. The current ionized water is similar to rain, tion or transport behavior in state of knowledge about nanomameaning that even though SWNTs aquatic environments,” Elimelech terials, she says, is not unlike the might aggregate or stick to soil says, but carbon nanotubes have leaps and bounds made by scienparticles, they might also be reextremely long aspect ratios, tists exploring hydrophobic commobilized in surface soils during meaning they are like skinny long pounds in the environment three heavy rains, the team hypothstraws, at a nanometer or two decades ago, which “also required esized. The next step, says wide by thousands of nanometers huge technology advances.” Elimelech, will be to examine the long. “We suspected [that SWNTs] The paper also “shows us how interaction between these nanowould have different transport far ahead we are with our use of materials and real soils outside of behavior,” he adds, atypical of the the technology, and how little we the lab by investigating the root average colloidal particle or reknow about its environmental bezones of plants and the changes lated fullerene nanoparticles. havior ... We do know the ubiquity that SWNTs might cause in soil Led by postdoctoral researcher of nanotech products in society microbial communities. Deb Jaisi, the team took comalready, and the understanding of Elimelech, a past member of mercial SWNTs, sonicated them their environmental behavior is still ES&T ’s editorial advisory board, to break up the aggregated in its infancy,” Diamond adds. started out looking at colloids while clumps, and then ran them —NAOMI LUBICK he was a graduate student of through sand columns in the lab Charles O’Melia at Johns Hopkins using different ionic solutions. 10.1021/es900421h
2009 American Chemical Society
Published on Web 02/25/2009
April 1, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 2197
