Featured Research

from universities, journals, and other organizations

Environmental Fate: Industrial Nanomaterials Appear Vulnerable To Dispersal In Natural Environment

Date:
December 23, 2006
Source:
Georgia Institute of Technology
Summary:
Laboratory experiments with a type of nanomaterial that has great promise for industrial use show significant potential for dispersal in aquatic environments -- especially when natural organic materials are present, according to research led by the Georgia Institute of Technology.

When mixed with natural organic matter in water from the Suwannee River -- a relatively unpolluted waterway that originates in southern Georgia -- multiwalled carbon nanotubes (MWNTs) remain suspended for more than a month, making them more likely to be transported in the environment, according to Georgia Tech researcher Jaehong Kim. (Georgia Tech Photo by Gary Meek)

Laboratory experiments with a type of nanomaterial that has great promise for industrial use show significant potential for dispersal in aquatic environments -- especially when natural organic materials are present.

When mixed with natural organic matter in water from the Suwannee River -- a relatively unpolluted waterway that originates in southern Georgia -- multiwalled carbon nanotubes (MWNTs) remain suspended for more than a month, making them more likely to be transported in the environment, according to research led by the Georgia Institute of Technology.

Carbon nanotubes, which can be single- or multiwalled, are cylindrical carbon structures with novel properties that make them potentially useful in a wide variety of applications including electronics, composites, optics and pharmaceuticals.

"We found that natural organic matter, or NOM as we call it, was efficient at suspending the nanotubes in water," said Jaehong Kim, an assistant professor in the Georgia Tech School of Civil and Environmental Engineering.

The research will be published in the January issue of the American Chemical Society journal Environmental Science & Technology. Kim is the senior author and conducted the research with Professor Joseph Hughes, graduate student Hoon Hyung, both at Georgia Tech, and postdoctoral researcher John Fortner from Georgia Tech and Rice University. The U.S. Environmental Protection Agency funded the research.

"We don't know for certain why NOM is so efficient at suspending these nanotubes in the laboratory," Kim said. "We think NOM has some chemical characteristics that promote adhesion to the nanotubes more than to some surfactants. We are now studying this further."

In the lab, Kim and his colleagues compared the interactions of various concentrations of MWNTs with different aqueous environments organic-free water, water containing a 1 percent solution of the surfactant sodium dodecyl sulfate (SDS), water containing a commercially available sample of Suwannee River NOM and an actual sample of Suwannee River water from the same location as the commercially available preparation. They agitated each sample for one hour and then let it sit for up to one month.

The researchers then used transmission electron microscopy (TEM), measurements of opacity and turbidity, and other analyses to determine the behavior of MWNTs in these environments. The results were:

  • MWNTs added to organic-free water settled quickly, and the water became completely transparent in less than an hour.
  • When added to the SDS solution, the nanotubes immediately made the water dark and cloudy. After one day of settling, some nanotubes remained suspended, and the water was a light gray color.
  • Water containing the commercially available sample of Suwannee River NOM originally appeared dark and cloudy, then gradually lightened after four days of settling. Some MWNTs remained suspended for more than a month.
  • The results with an actual Suwannee River sample were similar to those with the commercially available preparation.

In addition, Kim and his colleagues used TEM to find that most MWNTs in both samples of NOM were suspended as individually dispersed nanotubes, rather than being clustered together as some other nanomaterials do in water. "This individual dispersion might make them more likely to be transported in a natural environment," Kim explained.

In light of these findings, Kim and his colleagues have expanded their research to other nanomaterials, including single-walled carbon nanotubes and C60, the so-called "buckyball" molecules in the same family as carbon nanotubes. They are also experimenting with other NOM sources and studying different mixing conditions. "We are getting some interesting results, though our findings are still preliminary," Kim noted.

While researchers explore applications of nanomaterials and industry nears commercial manufacture of these novel products, it's essential for scientists and engineers to study the materials' potential environmental impact, Kim added.

"Natural organic matter is heterogeneous," he explained. "It's a complex mixture made from plants and microorganisms, and it's largely undefined and variable depending on the source. So we have to continue to study nanomaterial transport in the lab using various NOM sources to try to better understand their potential interaction in the natural environment."

In related research, Kim's research team is studying various other aspects of the fate of nanomaterials in water -- including photochemical and chemical reactions of C60 colloidal aggregates -- with the ultimate goal of understanding the environmental implications of nanotechnology.


Story Source:

The above story is based on materials provided by Georgia Institute of Technology. Note: Materials may be edited for content and length.


Cite This Page:

Georgia Institute of Technology. "Environmental Fate: Industrial Nanomaterials Appear Vulnerable To Dispersal In Natural Environment." ScienceDaily. ScienceDaily, 23 December 2006. <www.sciencedaily.com/releases/2006/12/061219095439.htm>.
Georgia Institute of Technology. (2006, December 23). Environmental Fate: Industrial Nanomaterials Appear Vulnerable To Dispersal In Natural Environment. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2006/12/061219095439.htm
Georgia Institute of Technology. "Environmental Fate: Industrial Nanomaterials Appear Vulnerable To Dispersal In Natural Environment." ScienceDaily. www.sciencedaily.com/releases/2006/12/061219095439.htm (accessed April 18, 2014).

Share This



More Earth & Climate News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Drought Concerns May Hurt Lake Tourism

Drought Concerns May Hurt Lake Tourism

AP (Apr. 18, 2014) Operators of recreational businesses on western reservoirs worry that ongoing drought concerns will keep boaters and other visitors from flocking to the popular summer attractions. (April 18) Video provided by AP
Powered by NewsLook.com
First Ever 'Female Penis' Discovered In Animal Kingdom

First Ever 'Female Penis' Discovered In Animal Kingdom

Newsy (Apr. 18, 2014) Not only are these newly discovered bugs' sex organs reversed, but they also mate for up to 70 hours. Video provided by Newsy
Powered by NewsLook.com
Ark. Man Finds 6-Carat Diamond At State Park

Ark. Man Finds 6-Carat Diamond At State Park

Newsy (Apr. 18, 2014) An Arkansas man has found a nearly 6.2-carat diamond, which he dubbed "The Limitless Diamond," at the Crater of Diamonds State Park. Video provided by Newsy
Powered by NewsLook.com
Deadly Avalanche Sweeps Slopes of Mount Everest

Deadly Avalanche Sweeps Slopes of Mount Everest

AP (Apr. 18, 2014) At least six Nepalese guides are dead after an avalanche swept the slopes of Mount Everest along a route used to climb the world's highest peak. (April 18) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins