2022-06-29

Scientists develop low-cost filters to remove heavy metals from water using plant waste

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Scientists develop low-cost filters to remove heavy metals from water using plant waste

They first extracted protein from peanut and sunflower seed meal, and then wound the protein chains together to form a nano-scale rope like structure called protein amyloid fiber. The cellulose is then combined with activated carbon to form a mixed filter membrane.

When these membranes were used to filter the water polluted by lead, platinum and chromium, it was found that they could remove up to 99.89% of these heavy metals, making the water meet the international drinking water standards. This effect is mainly due to the fact that cellulose acts as a “molecular sieve”, attracting and capturing heavy metal ions.

According to scientists’ calculations, only 16KG of sunflower protein is needed to filter the same amount of lead polluted Olympic scale swimming pool. When the membranes are indeed saturated with trapped metal, they can be dried and then burned. Doing so will destroy the cellulose but leave the metal, allowing more valuable metals (such as platinum) to be recovered.

Scientists develop low-cost filters to remove heavy metals from water using plant waste(1)

In addition, protein amyloid fibers remain in the membrane when used, rather than being released into filtered water. This is an important fact, because when amyloid is formed and accumulated in the body, it will lead to tissue damage and organ failure.

Now people hope that, once further developed, the filter membrane can become a low-cost substitute for traditional technologies such as reverse osmosis, because reverse osmosis technology is not only more expensive, but also requires power sources. As an additional benefit, the membrane will provide another use for rapeseed meal, which is sometimes used as animal feed but is often only discarded.

Scientists develop low-cost filters to remove heavy metals from water using plant waste(2)

Professor Ali miserez of Nanyang Technological University in Singapore and Professor Raffaele mezzenga of the Federal Institute of technology in Zurich, Switzerland, led the study. “Our protein-based membranes are created through a green and sustainable process that requires little electricity to operate, making them available for use around the world, especially in less developed countries. Our work places heavy metals in its place – as a type of music, not as a pollutant in drinking water,” miserez said

The study was described in a recent paper published in the Journal of chemical engineering.