Skip to Content
Uncategorized

Nanofilters

November 1, 2004

Every day, an estimated 3,000 to 6,000 people worldwide die from diseases caused by contaminated water. Filtration can reduce the risks, but traditional bacterial and viral filters trap pathogens inside granular carbon or porous ceramic or polymer materials, many of which are difficult to clean and must be changed frequently.

Now scientists are turning to carbon nanotubes. A team from Rensselaer Polytechnic Institute in Troy, NY, and the Banaras Hindu University in Varanasi, India, has devised a way to get millions of the large carbon molecules to collect on the inside surface of a quartz tube about a centimeter across. The resulting tube-inside-a-tube consists of radially oriented nanotubes, packed as tightly as a fistful of spaghetti and bonded together; this structure can be detached from the quartz and extracted whole. With one of its ends capped and water pumped in through the other, such a cylinder acts as a filter. Water molecules can squeeze out through nanometer-sized gaps in the walls, but bacteria like E. coli and viruses like the 25-nanometer-wide poliovirus get stuck.

The structures are heat resistant and strong enough that they can be cleaned repeatedly using autoclaves or ultrasound devices like those at medical clinics and hospitals, making them reusable many times, says Pulickel M. Ajayan, the professor of materials engineering at Rensselaer who led the work.

Keep Reading

Most Popular

individual aging affects covid outcomes concept
individual aging affects covid outcomes concept

Anti-aging drugs are being tested as a way to treat covid

Drugs that rejuvenate our immune systems and make us biologically younger could help protect us from the disease’s worst effects.

close up of baby with a bottle
close up of baby with a bottle

The baby formula shortage has birthed a shady online marketplace

Desperate parents just want to feed their babies. They’re having to contend with misinformation, price gouging, and scams along the way.

"Olive Garden" NFTs concept
"Olive Garden" NFTs concept

I tried to buy an Olive Garden NFT. All I got was heartburn.

Our newest issue spells out what you need to know about the dizzying world of digital money.

Stay connected

Illustration by Rose WongIllustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.