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Institute of Physics - Carbon nanotube sponge shows improved water clean-up

DCN Corp® - Carbon nanotube (CNT) sponges which are doped with Sulphur demonstrated a high capacity to absorb oil, potentially opening up the possibility of using the material in industrial accidents and oil spill clean-ups. Credit - Institute of Physics (IOP) in its journal NanotechnologyA Carbon nanotube (CNT) sponge capable of soaking-up water contaminants, such as fertilisers, pesticides and pharmaceuticals, more than three times more efficient then previous endeavours has been presented in a new study published in Institute of Physics (IOP) journal Nanotechnology entitled A three-dimensional carbon nanotube network for water treatment. [1]

Typically CNTs are hollow cylindrical structures composed of a single sheet of Carbon (C).  Owing to their structure, CNTs have supreme thermal, chemical and mechanical properties, which has led to speculation of an array of applications ranging from body armour to solar panels.

In addition, CNTs have been touted as excellent candidates for waste water clean-up, but, unfortunately, problems have arisen when trying to handle the fine powders and eventually trying to retrieve them from the water.

Lead author was Luca Camilli, University of Roma, who stated - "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 on this study, are much easier to handle. They float on water because of their porous structure and once saturated with oil, can be easily removed. By simply squeezing them and releasing the oil, they can then be re-used."

In this 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 (S) during the production process with the resulting sponge having an average length of about 20 mm.

Addition of S caused defects to form on the surface of the CNT sponges which then enabled ferrocene, which was included during the production process, to deposit Iron (Fe) into tiny capsules within the carbon shells.

Presence of Fe meant that the sponges could be magnetically controlled and driven without any direct contact, easing the existing problem to trying to control CNTs when added on to the water's surface.

The researchers demonstrated how the constructed CNT sponges could successfully remove a toxic organic solvent, such as dichlorobenzene, from water, thus, 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 by up to 150 times of its initial weight and absorb engine oil to a slightly higher capacity then previously reported.

As stated by Camilli - "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."

"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." Original article available here

The research, above, clearly demonstrates the great potential in applying CNTs, and DCN Corp strongly believes it can contribute by efficiently manufacturing CNT base substrates. Going forward, if you and/or your colleagues are interested in making DCN Corp's alternative process reality - please ensure to contact the company as soon as practicably possible.

[1] Camilli, L., Pisani, C., Gautron, E., Scarselli, M., Castrucci, P., D'Orazio, F., Passacantando, M., Moscone, D. and Crescenzi, M. De A three-dimensional carbon nanotube network for water treatment. Nanotechnology 25, 6 (2014)