NTU scientists, in collaboration with ETH Zurich, Switzerland (ETHZ), have created a membrane made from a by-product of vegetable oil manufacturing, which can filter heavy metals from contaminated water .
The research team found that proteins derived from the by-products of peanut or sunflower oil production can very effectively attract heavy metal ions.
In tests, they showed that this attraction process, called adsorption, was able to purify contaminated water to a degree that meets international drinking standards.
The production of commercial domestic vegetable oils generates waste by-products called oilseed meals – protein-rich leftovers that remain after the oil has been extracted from the raw plant.
After extracting the proteins from the oilseed meal, the team turned them into nanometer-sized protein amyloid fibrils, which are rope-like structures made of tightly coiled proteins.
These protein amyloid fibrils are attracted to heavy metals and act as a molecular sieve, trapping heavy metal ions as they pass.
The researchers combined the extracted amyloid fibrils with activated charcoal – a commonly used filtration material – to form a hybrid membrane. They discovered that their membranes filtered out up to 99.89% of heavy metals.
Of the three metals tested, the filter was most effective for lead and platinum, followed by chromium.
The researchers’ membrane has the potential to be a cheap, low-energy, durable and scalable method for decontaminating heavy metals from water.
Their membrane allows sustainable use of oilseed waste that would otherwise be discarded or used as food for animal feed.
Another big advantage, according to the researchers, is that this filtration requires little or no energy, unlike other methods like reverse osmosis which require electricity.
Reference: Soon WL, Peydayesh M, Mezzenga R, Miserez A. Plant-based amyloids from food waste to remove heavy metals from contaminated water. Chim Eng J. 2022;445:136513. doi:10.1016/j.cej.2022.136513
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