Published on August 26th, 2013 | by James Ayre6
Plasma-treated, Carbon-nanotube Filters For Water Purification In Developing Countries
August 26th, 2013 by James Ayre
Plasma-treated carbon nanotubes can function very effectively as an inexpensive means of purifying water in developing countries, according to new research from the Singapore University of Technology and Design. Water purification membranes enhanced with the plasma-treated carbon nanotubes are ‘perfectly’ structured for the removal of contaminants and brine from water, according to the new work.
As the researchers note, clean water is in very short supply throughout much of the ‘developing’ world — a cheap, portable, effective means of water purification would be of high utility to those living in such parts of the world. This reality is what drove the new work. The research “paves the way for the next generation of portable water purification devices,” as the researchers put it. (Note — it’s currently estimated that at least 780 million people around the world don’t have access to a clean water supply.)
With regard to the new work, the researchers state that the new membranes could be easily integrated into portable water purification devices — greatly outperforming most other existing filtration methods, and also being completely rechargeable and inexpensive.
“Small portable purification devices are increasingly recognized as the best way to meet the needs of clean water and sanitation in developing countries and in remote locations, minimizing the risk of many serious diseases,” states lead researcher Dr Zhaojun Han, from CSIRO’s world-leading Plasma Nanoscience Laboratories. “The large industrialized purification plants we see in other parts of the world are just not practical — they consume a large amount of energy and have high labour costs, making them very expensive to run.”
The researchers note that, while there are already a variety of portable water purification devices on the market, because those devices’ rely on reverse osmosis and thermal processes, they are “unable to filter out organic contaminants from the briny water found in some river and lake systems.”
“For people in remote locations, briny water can sometimes be the only available water source,” Dr Han continues. “That’s why it’s important to not only be able to remove salts from water, but to also be able to put it through a process of purification. Our study showed that carbon nanotube membranes were able to filter out ions of vastly different sizes — meaning they were able to remove salt, along with other impurities.”
Researcher Kostya (Ken) Ostrikov notes that existing portable devices also possess the downside of being reliant upon a continuous power supply to operate their thermal processes, whereas the new device doesn’t.
Professor Ostrikov explains what makes the new device so effective: “Firstly, ultralong nanotubes have a very large surface area that is ideal for filtration. Secondly, nanotubes are easy to modify, which allows us to tailor their surface properties through localized nanoscale plasma treatment.”
The researchers are now planning to continue their work by investigating the filtration properties of other nanomaterials — with graphene being the next material that they have in mind. By substituting graphene for the carbon nanotubes, the researchers think that the technology can be made more durable.