Graphene’s Role in Making Arsenic-Free Water (2010.7.20)
Arsenic is a very toxic substance most widely used for wood preservers because it is a strong killer of insects and bacteria. It is also being applied in the manufacture of agrichemicals such as pesticides, insecticides and herbicides; but its usage has been declining because of adverse effects on the environment.
Due to its odorless and colorless character, and its capacity to become transferred easily, arsenic intake can occur accidentally by drinking allegedly “clean” water. The World Health Organization estimated that approximately 57 million people worldwide are drinking arsenic-contaminated water with carcinogenic properties. Not surprisingly, casualties caused by arsenic poisoning have been reported in the past years, most prevalently in countries like Bangladesh, Taiwan, and Pakistan.
But recently, Professor Kwang Soo Kim at POSTECH’s Department of Chemistry, a celebrity in his field nominated as a National Scientist by the Korean government, found a novel solution. He discovered that arsenic can be filtered from pure water up to 99.99% using graphene, a new material gaining spotlight for future information technology. Apparently, this is an entirely different role of graphene.
In joint research with Professor In-Chul Hwang and in alliance with POSCO, he has developed a hybrid compound by combining magnetite and Reduced Graphene Oxide (RGO), which can greatly reduce the amount of arsenic in water by down to one billionth (1 ppb). The methodology has attracted attention of the scientific world for its genuineness and practicality. The work was published in a well-known journal, American Chemical Society Nano.
Until now, magnetites, significant ores of iron possessing a very strong magnetic property enough to be a natural magnet, have been used to purify polluted water. But they had a drawback of only being useful for pooled water because magnetite particles become oxidized quickly when exposed to air.
However, the new technique of Professor Kim’s team addressed the issue from a very different angle. They sprayed ten nanometers of magnetite-RGO compound into the arsenic contaminated water and isolated the arsenic content using a magnet. Afterwards, they would retrieve the isolated arsenic instantaneously out of the water, in a similar fashion to fishing. By doing so, arsenic in flowing water could also become extracted, leaving the water clean.
“Magnetites are commonly used in many areas, but by applying Reduced Graphene Oxide films to them, our team was able to free water from arsenic poisoning in a more stabilized way, and also expand the adhesion area of arsenic,” commented Professor Kim on his team’s new outcome. Furthermore, he revealed “Now we can purify arsenic water pollution with strongly adhering arsenic 3 and arsenic 5 compounds, which are well-known for their toxicity.”