Carbon nanotube sponge shows improved water clean-up

Jan 16, 2014
Carbon nanotube sponge shows improved water clean-up

A carbon nanotube sponge capable of soaking up water contaminants, such as fertilisers, pesticides and pharmaceuticals, more than three times more efficiently than previous efforts has been presented in a new study published today.

The (CNT) , uniquely doped with sulphur, also demonstrated a high capacity to absorb oil, potentially opening up the possibility of using the material in industrial accidents and oil spill clean-ups.

The results have been published today, 17 January, in IOP Publishing's journal Nanotechnology.

CNTs are hollow cylindrical structures composed of a single sheet of carbon. Owing to their structure, CNTs have extraordinary thermal, chemical and mechanical properties that have led to an array of applications from body armour to solar panels.

They have been touted as excellent candidates for wastewater clean-up; however, problems have arisen when trying to handle the fine powders and eventually retrieve them from the water.

Lead author of the research Luca Camilli, from the University of Roma, said: "It is quite tricky using CNT powders to remove oil spilled in the ocean. They are hard to handle and can eventually get lost or dispersed in the ocean after they are released.

"However, millimetre- or centimetre-scale CNTs, as we've synthesised in this study, are much easier to handle. They float on water because of their and, once saturated with oil, can be easily removed. By simply squeezing them and releasing the oil, they can then be re-used."

In the new study, the researchers, from the University of Roma, University of Nantes and University of L'Aquila, bulked up the CNTs to the necessary size by adding sulphur during the production process—the resulting sponge had an average length of 20 mm.

The addition of sulphur caused defects to form on the surface of the CNT sponges which then enabled ferrocene, which was also added during the production process, to deposit iron into tiny capsules within the carbon shells.

The presence of iron meant the sponges could be magnetically controlled and driven without any direct contact, easing the existing problem of trying to control CNTs when added onto the water's surface.

The researchers demonstrated how the constructed CNT sponges could successfully remove a toxic organic solvent—dichlorobenzene—from water, showing that it could absorb a mass that was 3.5 times higher than previously achieved.

The CNT sponges were also shown to absorb vegetable oil up to 150 times of its initial weight and absorb engine to a slightly higher capacity than previous reported.

"The improved absorption properties of the sponge are down to the porous structure and the rough surface of the CNTs. Oils or solvent can easily be absorbed in the empty spaces amongst the CNTs, which is made easier by the rough surfaces," continued Camilli.

"The next stage of our research is to improve the synthesis process so that the sponges can be produced on a commercial scale. We must also study the toxicity of the sponges before any real-world applications can be realised."

Explore further: Spider's web weaves way to advanced networks and displays

More information: 'A three-dimensional carbon nanotube network for water treatment' L Camilli et al 2014 Nanotechnology 25 065701 will be freely available online from 17 January 2014. iopscience.iop.org/0957-4484/25/6/065701/article

Related Stories

Carbon nanotube composites for enzymes and cosmetics

Sep 06, 2011

Japanese researchers have developed a low cost and efficient method for producing electrically conducting composites based on electrostatic adsorption of CNTs onto resin and ceramic particles for applications ...

Recommended for you

The simplest element: Turning hydrogen into 'graphene'

Dec 16, 2014

New work from Carnegie's Ivan Naumov and Russell Hemley delves into the chemistry underlying some surprising recent observations about hydrogen, and reveals remarkable parallels between hydrogen and graphene ...

Future batteries: Lithium-sulfur with a graphene wrapper

Dec 16, 2014

What do you get when you wrap a thin sheet of the "wonder material" graphene around a novel multifunctional sulfur electrode that combines an energy storage unit and electron/ion transfer networks? An extremely ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

Returners
not rated yet Jan 16, 2014
No mention of the fact CNT accumulate in lab animals gut and lungs (as per articles here a few years ago,) nor how they intend to prevent the CNT from being dispersed into the environment, and contaminating food animals, like fish or shellfish, since you mentioned oil spills.

AS I recall from the lab experiments, this stuff behaves a lot like Asbestos when in the lungs. TO my mind, that means its a terrible option as a cleaning agent, and should only be used in applications where it is coated or contained with something else to prevent it's escape into the environment, where it will be inhaled or ingested by us all.
Mike_Massen
not rated yet Jan 17, 2014
Returners could do with research before wandering a negative/alarming path as CNT are so easily produced from various types of organic combustion in nature, its very likely we have been exposed to CNT's of various compositions for many millenia.

Eg. Mucous in lungs has various obvious adaptations.

Much like Copper during the start of the chalcolithic era (~5000 years ago), societies (predominantly in Europe at first) who cooked & stored food in copper vessels were exposed to ~50mg per day & continued for long enough periods for selection to add influence re toxicity affecting procreation favouring mutations to manage this & use it for benefit etc.

Biochemistry of adaptation offers usage of a free resource, Eg Cerruloplasmin (the body's copper truck) is a very powerful anti-oxidant, more than Vit C.

This almost all stopped ~200 years ago, such that now, in our food production processes we ingest ~250ug/day - ie some 200 times LESS.

ie. CNT's, consider fire exposure history !

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.