A new study published in Nature Communications reveals that access to safe drinking water is a step closer to being a reality in developing countries.
The study paves the way for the next generation of portable water purification devices, which could provide relief to the 780 million people around the world who do not have access to a clean water supply.
An international team of researchers led by Associate Professor Hui Ying Yang from Singapore University of Technology and Design showed that water purification membranes enhanced by plasma-treated carbon nanotubes were ideal for removing contaminants and brine from water. The team included Dr Zhaojun Han and Professor Kostya (Ken) Ostrikov from CSIRO’s world-leading Plasma Nanoscience Laboratories.
Dr Han explains that these membranes could be integrated into portable water purification devices about the size of a tea pot that 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.
According to Dr Han, small portable purification devices are increasingly recognised as the best way to meet the needs of clean water and sanitation in developing countries and in remote locations, minimising the risk of many serious diseases.
Existing portable devices rely on reverse osmosis and thermal processes, and can remove salt ions but are unable to filter out organic contaminants from the briny water found in some river and lake systems.
Dr Han says briny water may sometimes be the only available water source for people in remote locations; therefore it is important to not only be able to remove salts from water, but also put it through a process of purification.
The international study showed that carbon nanotube membranes were able to filter out ions of vastly different sizes, allowing salt as well as other impurities to be removed.
Additionally, existing portable devices require a continuous power supply to operate their thermal processes but the new membranes could be operated as a rechargeable device.
Professor Ostrikov attributes the success of the new membranes to the unique properties of plasma treated carbon nanotubes.
The researchers now plan to extend their research to investigate the filtration properties of other nanomaterials, beginning with graphene, which has similar properties to carbon nanotubes, but could be made considerably denser and stronger.
The study ‘Carbon nanotube membranes with ultrahigh specific capacity for water desalination and purification’ is a collaborative work between Singapore University of Technology and Design, CSIRO, Massachusetts Institute of technology (MIT), the University of Sydney, and Hong Kong Polytechnic University.