
Asian Scientist (Aug. 20, 2013) – An international team of scientists has found that water purification membranes enhanced by plasma-treated carbon nanotubes are ideal for removing contaminants and brine from water.
The discovery, published in Nature Communications, paves the way for the next generation of portable water purification devices.
According to Dr Zhaojun Han, a co-author of the study, these membranes can be integrated into portable water purification devices the size of a tea pot and would be rechargeable, inexpensive and more effective than many existing filtration methods. Contaminated water would go in one end, and clean drinkable water would come out the other.
“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,” said Dr Han.
“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.”
Dr Han acknowledges that some smaller portable devices do already exist. However, because they rely on reverse osmosis and thermal processes, they are able to remove salt ions but 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,” he says.
“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.”
The success of the new membranes can be attributed to the unique properties of plasma treated carbon nanotubes.
“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 localised nanoscale plasma treatment,” said Professor Kostya (Ken) Ostrikov, a member of the research team.
Now that the researchers have proven the effectiveness of the method, they plan to extend their research to investigate the filtration properties of other nanomaterials. They will begin by looking at graphene, which has similar properties to carbon nanotubes, but can be made considerably denser and stronger.
The article can be found at: Yang et al. (2013) Carbon Nanotube Membranes With Ultrahigh Specific Capacity For Water Desalination And Purification.
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Source: CSIRO; Photo: likeablerodent/Flickr/CC.
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