Making drinking water safer with new graphene filter

Posted Mar 24, 2018 by Tim Sandle
Australian researchers have developed a new filter that can remove organic matter from water intended to be of drinking water quality. In trials, 99 percent of the impurities can be removed through the filter process.
Water Fill-up
Filling up a reuseable water container.
Stephanie Dearing
The development comes from the University of New South Wales. Here scientists have constructed a graphene-based, laboratory-scale filter. The filter is intended to remove the natural organic matter that is left behind during conventional treatment processing of drinking water.
Working with Sydney Water the researchers showed that the laboratory tests on filtered water, drawn from the Nepean Water Filtration Plant in western Sydney, achieved a 99 percent filtration success. Based on this the researchers are developing a scale-up of the new technology. It is hoped that the technology can be retrofitted to conventional water treatment plants.
The reason why the research focuses on natural organic matter contaminants is because these particles can affect the performance of filtration plants and over-time the matter can reduce the capacity of the plant to function effectively, especially after periods of heavy rain.
Conventional treatments involve the use of chemical coagulants, but these methods are not totally effective. Filtration has been shown to be a superior method. With the new filter, the researchers converted naturally occurring graphite into graphene oxide membranes. These membranes enable high water flow at atmospheric pressure.
Graphene in its basic form, is a one-atom thick sheet of carbon. The material is light, transparent, strong and very conductive. Graphene oxide is graphite oxide, which is an oxidized form of a compound of carbon, oxygen, and hydrogen in variable ratios, arranged in sheets. Once these sheets become monomolecular (that is, one molecule thick) graphene oxide is formed. Graphene oxide sheets can be used to prepare strong paper-like materials like membranes.
Graphene-oxide membranes are attracting considerable attention as promising candidates for new filtration technologies, with the potential of filtering out small nanoparticles, organic molecules, and even large salts. With the filter, tiny capillaries of the graphene-oxide membranes function to block the salt from flowing along with the water as it passes through the filter.
Speaking with the magazine Controlled Environments, lead researcher Dr. Rakesh Joshi said: “Our advance is to use filters based on graphene — an extremely thin form of carbon. No other filtration method has come close to removing 99 percent of natural organic matter from water at low pressure.”
The experimental findings have been published in the journal Carbon. The research paper is titled “Application of graphene oxide membranes for removal of natural organic matter from water.”
Digital Journal’s science pages contain a number of articles on the subject of graphene and its many and varied applications.