New substance uses orange peel to absorb mercury from water
Australian researchers are seeking an international patent after discovering that harmful mercury can be removed from water using industrial waste and orange peels.
Mercury leaks into water and soil stores as a result of mining and burning fossil fuels. It is toxic for the majority of birds and fishes it contacts and has previously been linked with stunting brain development in children.
In August last year, a letter published in the peer-review journal Nature stated that the amount of mercury near the surface of many of the world’s oceans had tripled as the result of polluting activities.
However, synthetic chemist Dr Justin Chalker and his team of researchers at Flinders University, Australia have developed a solution they call Sulphur-Limonene Polysulfide (SLP) made from sulphur and limonene found in orange peel.
Both of the products are readily available and cheap to acquire, with Dr Chalker saying, ‘It literally grows on trees’. The plastic-like product can absorb toxic mercury from water sources and soil.
Once SLP has absorbed the mercury it remains permanently bound to the substance eliminating environmental risks and making the water nearly drinkable, reducing the concentration of mercury in the water by a thousand fold.
Solutions to increase the availability of drinking water are urgently needed, with two thirds of the world’s population expeted to be living in water-stressed areas by 2025.
Dr Chalker said: “To make the SLP polymer, we melt the sulphur, and add limonene to it and then can coat devices or make it into any shape we like.”
“The mercury forms nano and micro-particles that are embedded in the polymer, and don’t get washed off even with flowing water.”
Over 70 million tonnes of sulphur is produced a year as a by-product from the crude oil industry, but it is limited in terms of usability. 70,000 tonnes of limonene is produced in the same time frame meaning that SLP can be produced in abundance.
It is hoped that large quantities of SLP can be deployed on river sites and other waterways to absorb mercury from these sources. The product will change colour when it absorbs mercury, which means it could also be used as a detection device to determine which waterways are polluted.