New Cheap Graphene Filters Can Make Even Seawater Safe to Drink

a_graphair_sample
GraphAir
Made using normal cooking oil, this graphene film could be a comercially viable way of filtering water on a huge scale.

GraphAir, a new type of graphene developed in Australia, can remove salt and contaminants from water in one easy step.

Author Ana Galán Herranz, 02.27.18

GraphAir, a new type of graphene developed in Australia, can remove salt and contaminants from water in one easy step.

According to statistics from the WHO, around 3 in 10 people worldwide (a whole 2.1 billion people) lack access to safe, readily available water at home. CSIRO (Commonwealth Scientific and Industrial Research Organization) scientists, in Australia, have now come up with a new type of graphene that can purify water in a cheap, simple and effective way.

Graphene is a carbon material, just one atom thick, and usually very expensive and tricky to make, using explosive compressed gases and vacuum processing. This version, made using soybean oil, is much easier and cheaper to produce than usual graphene but retains graphene’s usual properties, making it much more commercially viable.

GraphAir is the name they’ve given to this material – a thin film with nano-channels that allow water to pass through but not pollutants. “In Graphair we’ve found a perfect filter for water purification. It can replace the complex, time consuming and multi-stage processes currently needed with a single step,” said CSIRO scientist Dr Dong Han Seo in a press release. He is also the lead author of a paper on GraphAir submitted and published in Nature Communications.

The paper shows the results of the different experiments using both a GraphAir biofilm sheet and a normal filter on polluted seawater from Sydney harbour. “Conventional water filter membranes used in water purification are made from polymers (plastics) and cannot handle a diverse mix of contaminants; they clog or allow contaminants to pass through, so they have to be separated out before the water is filtered,” the paper states.

When used by itself, a water filtration membrane becomes coated with contaminants, blocking the pores that allow the water through, but when the GraphAir membrane is added, it can clean even the highly polluted water from the Sydney port in one step. It continued to remove 99 per cent of contaminants, even when coated with pollutants “All that’s needed is heat, our graphene, a membrane filter and a small water pump. We’re hoping to commence field trials in a developing world community next year,” said Dong Han Seo.

According to WHO data, around 500,000 people die yearly from illnesses after drinking polluted water, most of them children. Consuming contaminated drinking water can cause diarrheal diseases (cholera, dysentery, polio, typhoid) and parasites, such as giardia, which can be lethal in areas with limited access to medical care. This technology could help to provide safe drinking water to those regions in a fast, cheap and sustainable way.

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