Climate change solutions
We deliver game-changing environmental solutions that have a real impact for people around the globe.
Featured
Our impact
For more almost 60 years, we have been building innovative solutions to the biggest environmental challenges — from the soil to the sky.
Featured
About us
Guided by science and economics, and committed to climate justice, we work in the places, on the projects and with the people that can make the biggest difference.
Featured
Get involved
If we act now — together — there’s still time to build a future where people, the economy and the Earth can all thrive. Every one of us has a role to play. Choose yours.
Featured
News and stories
Stay informed and get inspired with our in-depth reporting about the people and ideas making a difference, insight from our experts and the latest environmental progress.
Featured
    • EDF Health

    Chemical Concerns – Insights on Air Pollution, Public Health, and Chemical Safety

    My CNT is Better than Your CNT… Or At Least It’s Different

    Posted: in Health science, Nanotechnology

    Written By

    Share

    Cal Baier-Anderson, Ph.D., is a Health Scientist.

    After posting to this blog the other day, I came across a brand new study characterizing the heterogeneity of carbon nanotubes.  The authors of this study looked at 11 single-wall carbon nanotubes (SWCNTs) from 10 different suppliers and found that SWCNT composition varies dramatically depending on synthesis method, feedstock, purification steps, and other factors. 

    The authors note that SWCNTs contain up to 70% impurities.  In this study, detected impurities include metals used commonly as catalysts, such as iron, nickel, cobalt and yttrium.  Ironically, adding a purification step to remove residual metal catalysts can actually add small amounts of new metals, such as copper, lead, and chromium!  The authors speculate that the acid washing process used in the purification step transfers metals from lab equipment to the SWCNTs, but this hypothesis needs to be tested.

    Remarkably, the total carbon content of the SWCNT also varies considerably, ranging from 60-97%.  Even more variable is the percentage of carbon in the lattice form that distinguishes SWCNT from amorphous carbon (a measure of structural purity): that ranged from 23–81%.

    The authors hypothesize that the heterogeneity of SWCNTs manufactured with different techniques could have a profound influence on the associated toxicity.  This real-world heterogeneity seen even within one class of nanomaterials further illustrates how difficult it will be to derive general principles to predict the effects of exposure to nanomaterials on human health and the environment.

    One Comment

    1. Andrew Maynard
      Posted April 12, 2008 at 11:44 am | Permalink

      Cal,

      An interesting aside to this – last year we published a paper looking at the physical characteristics of airborne aggregates released from single waled carbon nanotube paper. One surprising outcome was that two different batches of what was purportedly the same material led to completely different particles being released; most likely with very different risk profiles. From the first batch, particles were compact and predominantly non-nanotube carbonaceous material. But from the second batch, very open-structured aggregates of carbon nanotubes were released.

      Andrew

    Related Posts