When orange peel preserves the earth

Posted on 25 February 2016.

Detecting and cleaning up mercury pollution using orange peels and sulfur? Yes, it's true! Australian researchers have managed it!

Starting from some fruit and a happy accident, they have a lot in common with the Tatin sisters and their famous tart. But the comparison stops there. Because their discovery is not culinary, but revolutionary. In Adelaide, in southern Australia, the laboratories at Flinders University were the scene of an incredible discovery. Wanting to create a polymer from recycled organic waste, Dr. Justin Chalker and his team invented a mercury vacuum cleaner.

Orange and oil waste can finally be recycled

Every year, the oil industry produces 70 million metric tonnes of sulfur, a byproduct considered to be waste. Ditto for the peel from the citrus industry – 70,000 metric tonnes per year - which goes in the trash. However, orange oil contains a useful substance, limonene, which, when it met sulfur in Dr. Chalker’s laboratory, gave birth to the new sulfur-limonene polysulfide. The advantage is that it binds to heavy metals, such as mercury.

It turns yellow when it absorbs mercury

Forming a kind of dark red rubber, the polymer changes color when it absorbs mercury. In rivers, lakes and rivers it will measure pollution levels. Better still, this polymer can even suck up mercury from the water - which will then require little treatment to become safe to drink, according to the researchers in Adelaide.

From the ocean to your plate

The results - Dr. Chalker’s team are thinking about using this material to clean mercury from soil and from groundwater, or as a coating in transport and water filtration devices. Good news, because mercury is an endocrine disruptor with proven adverse effects. In our oceans alone, its concentration has tripled in 100 years. And as mercury lodges in the flesh of fish, it ends up on our plates.