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High school student leads contaminated water treatment breakthrough

An electron microscope image shows quartz fibers with carbon nanotubes after epoxidation. Experiments showed epoxidation appears to give the filters their absorptive quality Credit: Barron Research Group/Rice University
An electron microscope image shows quartz fibers with carbon nanotubes after epoxidation. Experiments showed epoxidation appears to give the filters their absorptive quality Credit: Barron Research Group/Rice University

Carbon nanotubes immobilised in a tuft of quartz fibre have the power to remove toxic heavy metals from water, according to new research from Rice University in the US and Swansea University in the UK.

Researchers have calculated that one gram of the remarkable material could treat 83,000 litres of contaminated water to meet World Health Organisation standards – enough to supply the needs of 11,000 people.

Fascinatingly, the award-winning new filters were developed in the lab of Rice University chemist Andrew Barron by Perry Alagappan – the lead author of the study who at the time was a high school student.

The material developed by Alagappan absorbs more than 99% of metals from samples laden with cadmium, cobalt, copper, mercury, nickel and lead. Significantly, the filters can be washed with a mild household chemical like vinegar and then reused.

Dubbed supported-epoxidised carbon nanotube (SENT) filters, the material consists of carbon nanotubes grown in place on quartz fibres that are then chemically epoxidised. Scaled up versions of the filters are proven to be able to treat 5 litres of water in under a minute, and can be renewed in 90 seconds. The material retained nearly 100% of its capacity to filter water for up to 70 litres per 100 grams of SENT, after which the metals contained could be extracted for reuse or turned into a solid for safe disposal.

In a press release, Barron pointed out that the raw materials needed to produce the filters are inexpensive, while the process of producing vinegar from acetic acid is practiced around the world, meaning recycling the filters in isolated locations should be relatively simple.

Alagappan, meanwhile, has won a series of awards for his research, both at home in the US and internationally. He sees the new technology having tremendous benefits to some of the most water starved, remote regions on earth, as well as having a use in industrial processes.

"This would make the biggest social impact on village-scale units that could treat water in remote, developing regions," Barron said. "However, there is also the potential to scale up metal extraction, in particular from mine wastewater." 

 

A study detailing the development of SENT has been published in the journal Scientific Reports

An electron microscope image shows quartz fibers with carbon nanotubes after epoxidation. Experiments showed epoxidation appears to give the filters their absorptive quality Credit: Barron Research Group/Rice University