Since the Industrial Revolution, when factories and mines first started spewing mercury into the environment, the amount of the heavy metal in the ocean has tripled. Some lakes and rivers are equally polluted. But researchers have discovered a cheap way that we might be able to start sucking mercury back out of the water.
A new type of rubber made from a combination of industrial waste and food scraps quickly absorbs mercury. Because it’s made from trash–a material found in orange peels called limonene, and sulfur waste from the petroleum industry–the material is very low cost to make.
Sulfur was already known for its ability to suck up mercury. But adding limonene to the mix makes the material flexible, so it can be molded into different shapes or used as a coating inside pipes or in a water filter. For large-scale remediation, water could flow over a bed made of the material.
It also can serve as a low-cost test to show if water is polluted. “The real surprise was that the material changes color when it binds to mercury,” says Justin Chalker, who developed the rubber at his lab at Flinders University in Australia.
Once the rubber is soaked with mercury, it could be replaced or potentially cleaned up and reused. “We are currently working on methods to recover the metal and reuse the polymer,” he says.
The researchers are already testing the material at old mines, a hotspot for mercury pollution. Here’s hoping it can eventually be used in the ocean, where over 80% of fish now contain unsafe levels of the toxin.