Microbeads could clean oceans of dangerous chemicals

Researchers have developed microbeads that can remove coral-killing chemicals from the ocean.

The next time you are at the beach, slathering on sunscreen, spare a thought for the coral reefs. According to a paper published in the journal Archives of Environmental Contamination and Toxicology, up to 14,000 tons of sunscreen washes off sunbathers and enters the world’s oceans each year. Most of this sunscreen contains a chemical called oxybenzone, which is used to deflect harmful UV rays. The problem is that very tiny amounts of oxygenone – less than one drop in 4 million gallons of water – is enough to kill all the nearby coral.

To try and save the world’s coral reefs, researchers from the University of Puerto Rico have developed absorbent beads which can soak up oxybenzone, and then be easily removed from the water. The beads are made of iron oxide nanoparticles which are embedded in a combination of non-toxic materials – alginate and chitosan. The oxybenzone bonds with the alginate, chitosan and iron oxide, and becomes trapped in the beads. Lead researcher Felix Roman explains that the beads can be dragged around the water in a net, or released into the ocean and then pulled out again later with a magnet. When tested on samples of seawater, the beads were able to remove even very high concentrations of the oxybenzone in as little as one hour. Once out of the water, the oxybenzone can then be removed from the beads so that they can be re-used.

The next step for the researchers is to increase the beads’ holding capacity to allow fewer beads to do the same amount of clean-up. The research team is also working on developing beads that can bind with different pollutants, to clean up other types of contamination. We have seen innovative materials used to clean up the air and remove mercury from the environment. Do the microbeads represent a new step forward for a clean ocean?