This site uses cookies. By continuing to use this site you agree to our use of cookies. To find out more, see our Privacy and Cookies policy.
Skip to the content

Share this

Free weekly newswire

Sign up to receive all our latest news direct to your inbox.

Physics on film

100 Second Science Your scientific questions answered simply by specialists in less than 100 seconds.

Watch now

Bright Recruits

At all stages of your career – whether you're an undergraduate, graduate, researcher or industry professional – can help find the job for you.

Find your perfect job

Physics connect

Are you looking for a supplier? Physics Connect lists thousands of scientific companies, businesses, non-profit organizations, institutions and experts worldwide.

Start your search today


Nanotubes and desalination

Is there anything that carbon nanotubes can’t do?

I know I’ve asked that question before — but I can’t stop being amazed at the fantastic properties of the tiny tubes.

This morning I heard Olgica Bakajin of Lawrence Livermore National Lab describe how she made a water filter using carbon nanotubes.

She did this by growing a forest of nanotubes on a silicon substrate and then filling in the gaps between the tubes with a nitride material.

After removing the silicon substrate, her team were left with a thin film that is permeated by nanotubes with an average diameter of about 1.6 nm — each of which turns out to be an excellent conductor of water.

Indeed, experiments showed that water flows through the nanotubes about four times faster than what would be expected from simple pipes.

The reason, according to Bakajin, is two fold. Firstly the walls of the nanotubes are hydrophobic — water molecules avoid the walls — which reduces drag. Also, the nanotubes are exceptionally smooth, again reducing drag.

And if that wasn’t good enough, the team found that the nanotube filters are very good at removing ions from water as it passes through. Bakajin thinks that the broken bonds at either end of the tubes attract the ions.

As a result, the filters could play an important role in the desalination of seawater — Bakajin’s filters were able to remove 40% of the chloride ions at a relatively high flow rate. This means that they already outperform commercial nanofilters.

The filters could be improved significantly by increasing the density of nanotubes in the filter; and optimizing the ends of the nanotubes for removing salt.

All of could mean highly-permeable filters that would reduce the amount of energy required in a desalination facility — perhaps making it economically viable.

This entry was posted in APS March Meeting 2009. Bookmark the permalink.
View all posts by this author  | View this author's profile

Comments are closed.


  • Comments should be relevant to the article and not be used to promote your own work, products or services.
  • Please keep your comments brief (we recommend a maximum of 250 words).
  • We reserve the right to remove excessively long, inappropriate or offensive entries.

Show/hide formatting guidelines

Tag Description Example Output
<a> Hyperlink <a href="">google</a> google
<abbr> Abbreviation <abbr title="World Health Organisation" >WHO</abbr> WHO
<acronym> Acronym <acronym title="as soon as possible">ASAP</acronym> ASAP
<b> Bold <b>Some text</b> Some text
<blockquote> Quoted from another source <blockquote cite="">IOP</blockquote>
<cite> Cite <cite>Diagram 1</cite> Diagram 1
<del> Deleted text From this line<del datetime="2012-12-17"> this text was deleted</del> From this line this text was deleted
<em> Emphasized text In this line<em> this text was emphasised</em> In this line this text was emphasised
<i> Italic <i>Some text</i> Some text
<q> Quotation WWF goal is to build a future <q cite="">
where people live in harmony with nature and animals</q>
WWF goal is to build a future
where people live in harmony with nature and animals
<strike> Strike text <strike>Some text</strike> Some text
<strong> Stronger emphasis of text <strong>Some text</strong> Some text