These microbots clean up radioactive waste – Headline Science

Most of the world’s energy comes from fossil
fuels. However, power plants running on coal and
natural gas release greenhouse gases and other pollutants harmful to human health and the
environment. That’s why scientists are exploring alternative
energy sources, and some experts say that nuclear power is the most efficient way to
meet the world’s growing energy demands without generating greenhouse gases. But scientists need a way to clean up radioactive
isotopes, both from wastewater generated by nuclear power plants, and from the environment
in case of a spill. Now, researchers reporting in ACS Nano have
developed tiny, self-propelled robots that remove radioactive uranium from simulated
wastewater. In the Chernobyl and Fukushima nuclear plant
disasters, radioactive material was accidentally released into the environment, threatening
humans and wildlife. Scientists have developed methods to remove
radioactive uranium from water, but they have limitations. One of the most promising recent approaches
is the use of metal-organic frameworks, or MOF. MOFs are compounds that can trap substances,
including radioactive uranium, within their hollow structures. Martin Pumera and colleagues wanted to add
a micromotor to a rod-shaped MOF called ZIF-8 to see if it could quickly clean up radioactive
waste. To make their self-propelled microbots, the
researchers designed ZIF-8 rods with diameters about 1/15 that of a human hair. They modified the rods to stabilize their
structures and make them magnetic. This way, the researchers could use magnets
to collect the microbots after they had done their jobs. Here, they’re using magnets to control the
rods’ motion. To give the microbots their own little motors,
the team placed catalytic platinum nanoparticles on one end. When they added a small amount of hydrogen
peroxide to the water, the platinum converted this “fuel” into oxygen bubbles, which
propelled the microbots at a speed of about 60 times their own length per second. In simulated radioactive wastewater, the microbots
removed 96% of the uranium in an hour. The team collected the uranium-loaded rods
with a magnet and stripped off the uranium, allowing the tiny robots to be recycled.

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