New Low-cost Filter Removes Toxic Metals in One Pass

A new water filter can remove toxic heavy metal ions and radioactive substances in just one pass.

The filter membrane is a hybrid of two low-cost materials: whey protein fibers and activated charcoal. The simple technology overcomes several disadvantages of existing methods, which are typically expensive and can only remove a specific element or have a very small filter capacity.

“The project is one of the most important things I might have ever done,” says Raffaele Mezzenga, a professor of food and soft materials at ETH Zurich. He and colleague Sreenath Bolisetty describe the technology in the journal Nature Nanotechnology.

At the heart of the filtration system is a new type of hybrid membrane made up of activated charcoal and tough, rigid whey protein fibers. The two components are inexpensive and simple to produce.

The whey proteins are denatured, which causes them to stretch, and ultimately come together in the form of amyloid fibrils. Together with activated carbon, these fibers are applied to a suitable substrate material, such as a cellulose filter paper. The carbon content is 98 percent, with a mere 2 percent made up by the protein.

The filter can even be used for recovering gold, read on to learn how.