Australasian Science: Australia's authority on science since 1938

Orange Peel Mops Up Mercury Pollution

Researchers at Flinders University have successfully created a new material made of industrial waste and unwanted orange peel that can suck mercury contamination out of water.

Mercury pollution occurs as a consequence of a number of industrial activities, including mining and the burning of fossil fuels. Mercury levels in the ocean have tripled since the beginning of the Industrial Revolution.

Mercury exposure – whether through the skin or through the ingestion of contaminated food, such as fish – damages the central nervous system and is particularly dangerous to pregnant women and children. Mercury also compromises the reproductive health of birds and fish.

The plastic-like substance, developed by Dr Justin Chalker of Flinders University, is made entirely from sulfur and limonene, which are waste products of industry and agriculture. Limonene is found mainly in orange peels.

Chalker says that the new polymer is cheap to produce due to the global abundance of waste sulfur and limonene, making it affordable to use in large-scale environmental clean-ups, to coat water pipes carrying domestic and waste water, and even to remove mercury from large bodies of water.

“More than 70 million tonnes of sulfur is produced each year by the petroleum industry, so there are literally mountains of it lying unused around the globe, while more than 70,000 tonnes of limonene is produced each year by the citrus industry.

“So not only is this new polymer good for solving the problem of mercury pollution, but it also has the added environmental bonus of putting this waste material to good use while converting them into a form that is much easier to store so that once the material is ‘full’ it can easily be removed and replaced.”

Another bonus is that the polymer can remove toxic metals from water, and even in small amounts can be used to detect mercury in areas where pollution is suspected due to a chemical reaction that causes the dark red polymer to turn bright yellow when it absorbs mercury.

The research has been published in Angewandte Chemie International Edition.