Cooking up a new method for mercury removal

An international team of scientists has devised a new way to extract the neurotoxin mercury from the environment — and their secret ingredient is cooking oil.

Led by Dr Justin M Chalker from Flinders University, the scientists combined second-hand cooking oil and sulfur — a common, low-cost by-product from petroleum production — to produce a new kind of polymer to use in remediation of soil, water and even the air. Writing in Chemistry: A European Journal, they revealed that their polymer can trap the most dangerous and common types of mercury pollution — mercury metal, mercury vapour and highly toxic organo-mercury compounds which harm both aquatic and terrestrial systems.

“We can use this material to protect the environment by capturing toxic mercury pollution — a pernicious problem around the world, causing brain damage and loss of IQ points in unborn children,” Dr Chalker said.

“Mercury is encountered in several industrial activities, including oil and gas refining and coal combustion. Alarmingly, mercury and mercury-containing materials are still used intentionally at many chloralkali plants and in artisanal gold mining. Additionally, mercury-based fungicides are still used in certain agricultural sectors.”

After absorbing mercury pollution, the novel rubber-like polymer changes colour to indicate the job is done. More of the polymer mixture can then be placed in the area to continue to process.

A polymer made from canola oil and sulfur (left) can remove mercury metal from soil. After reacting with mercury metal, the polymer changes colour from brown to black.

Dr Chalker said the development will enhance sustainability and environmental protection, with few remediation methods readily and affordably available. He noted that “every atom of the mercury-binding material can be derived from industrial by-products, so this is also an exciting advance in recycling and repurposing waste”.

Dr Chalker said the material is being tested in field trials at mining sites and areas where mercury-based fungicides are used. His team’s eventual goal is to deploy the solution at goldmines, as the largest source of mercury emissions globally is due to artisanal goldmining.

“In this practice, mercury metal is used to extract gold from ore,” he said. “The mercury-gold amalgam that forms is then heated, often with a hand torch or on a cooking stove, to vaporise the mercury and isolate the gold.

“The mercury-rich tailings and exposure to mercury vapour threaten the health of the nearly 15 million people involved in this process.”

The polymer is currently licensed for sale to Kerafast, a US-based reagent company whose primary aim is to make laboratory-made research tools easily accessible to the global scientific community.