Cleaning up oil spills is a difficult, dirty job, and even with modern techniques it’s still hard to remove every last drop.
Scientists from the University of Texas at Austin believe that they can fill that gap: they’re using a technique that targets and sucks up leftover minuscule oil droplets using electrostatic attraction and a magnet. In the future, a similar method could be used to clean lead and other contaminants from our drinking water, they say.
“You can separate out 95 per cent of the oil that’s in the water [using methods like skimming and centrifuging], but the stuff that’s left behind is these really small droplets,” said co-author Hugh Daigle, a geosystems engineering professor, in a phone interview. “We’re targeting that last five per cent of oil that’s really hard to get out using other techniques.”
They do this by dumping positively charged magnetic nanoparticles, which are made in the lab by coating the nanoparticles with polymers that have a positive surface charge, in oil-infested waters, said Daigle. Then, allowing time for the nanoparticles to attract to the negatively charged oil droplets, a magnet is used to pull the particle combination out of the water.
It’s reminiscent of method developed by another team, and previously covered on Motherboard, using a magnetic wand to clean up oil.
Watch more on Motherboard:
Before the oil-slicked water is considered clean, even the teeny tiny oil droplets need to be removed, so they don’t pose any further threat to the environment. So far, Daigle said, the process has a removal rate of 99 per cent, meaning that the level of oil remaining in the water is below any detectable limit. The study was published in the Journal of Nanoparticle Research.
It’s a fast process. The video showing the removal was shot in real-time and Daigle said that the treated nanoparticles mixed with the oil for only a minute or two beforehand. The sample size was small, so the next step comes with figuring out how to industrialize it.
Another method would be to feed the contaminated water through a tube where it gets mixed with the nanoparticles, goes through a magnetic filter, then flows out the other end. There are future plans to look into making the particles reuseable, and this summer, they plan to test out the nanoparticles on removing lead and other contaminants from drinking water.
“It’s a fairly simple process, we’ve used it for removing salt from water, polymer contaminants from water,” he said. “You just need to find the right surface coating to put on the nanoparticle to get it to be attracted to whatever contaminant you want to remove.”
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