Graphene goes green

Two new papers examine graphene's interaction with the environment, at the cradle and the grave.
Written by Melissa Mahony, Contributor

Concern over the potential consequences of human-made nanoparticles entering the various tiny and unintended crevasses of the environment and human body has grown in recent years. While there is much to learn about how the nano world may influence the macro one, researchers from Rice University are gaining insights into the relationship graphene has with the environment.

Graphene is a promising material for many things, from timely delivery of medicine to oil extraction. The ultra-thin, heat-transferring material has interested many as a possible substitute for silicon within electronics.

Electronics—new, old, discarded, recycled—are just about everywhere. Should graphene complement or in fact, displace silicon within our gadgets, how eco-friendly the substance is will be very important.

Two papers published this week in ACS Nano detail the two ends of graphene's life cycle. While many theories exist on how to best make graphene and graphene oxide (GO) in bulk, one paper demonstrates how to do so without emitting toxic gas.

Chemist James Tour of Rice University in a statement:

People were using potassium chlorate or sodium nitrates that release toxic gases – one of which, chlorine dioxide, is explosive. Manufacturers are always reluctant to go to a large scale with any process that generates explosive intermediates.

Many companies have started to make graphene and graphene oxide, and I think they're going to be very hard pressed to come up with a cheaper procedure that's this efficient and as safe and environmentally friendly.

The other study addresses how graphene will decompose in the environment. The research finds the almost ubiquitous Shewanella bacteria capable of breaking down GO into graphene. Stacks of graphene, which are single-atom carbon layers, become graphite, which is considered ecologically benign.

According to the researchers, the bacteria from the Shewanella family can also convert iron, chromium, uranium and arsenic compounds into less harmful substances and will be important to future bio-remediation efforts.

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Image: Everett Salas/Rice University
: ScienceDaily

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