A simple and effective technique to extract graphene, and the contaminants and toxins they from water using light has been developed by researchers at Monash University.The research work is being published in Nanoscale, the journal of the Royal Society of Chemistry. The new findings could considerably influence large volume water purification.

A small quantity of a special light-responsive soap was mixed with water containing contaminants and graphene. The molecular structure of the soap is changed when a specific colored light is shone at it. This makes the soap alter its interaction with carbon materials in the graphene, causing them to separate with the contaminants, which are stuck to them. When a different colored light is shone, the graphene is redispersed for reuse.

The various technological opportunities offered by graphene because of its unique structure and properties were described by Monash researcher Dr Rico Tabor.

By simply shining the right color of light on the graphene, contaminants and light-sensitive soap mixture, the graphene clusters together and sinks; shining a different color of light re-disperses it for re-use. (Credit: Monash University)

"Among its many potential uses, the prospect of using graphenes for the purpose of water purification is extremely promising. Because the structure is essentially two-dimensional and only an atom thick, graphene ‘sheets’ have the highest surface area possible, meaning their capacity to mop up contaminants in water surpass that of any currently used materials or membrane. However, this raises the problem of how to extract the graphenes and contaminants from water. Traditional approaches use high amounts of energy by centrifugation, or adding large amounts of polymer at high cost"

Dr Rico Tabor., Researcher, Monash University

The importance of these research findings and the advantages of utilizing light for the capture of graphene were described by the co-researcher Thomas McCoy.

"Light is appealing as it is abundantly available, simple and low cost when compared to most separation methods. Our latest research findings could have significant implications for cost-effective, large-scale water treatment."

Thomas McCoy, Monash University