New Low-cost Filter Removes Toxic Metals in One Pass


This hybrid membrane absorbs various heavy metals in a non-specific manner, including industrially relevant elements, such as lead, mercury, gold, and palladium. However, it also absorbs radioactive substances, such as uranium or phosphorus-32, which are relevant in nuclear waste or certain cancer therapies, respectively.

Gold removed and recovered from polluted water. (Credit: ETH Zurich/R. Mezzenga, S. Bolisetty)

The membrane also eliminates highly toxic metal cyanides from water. This class of materials includes gold cyanide, which is used commonly in the electronics industry to produce conductor tracks on circuit boards.

The membrane provides a simple way of filtering out and recovering the gold, thus the filter system could one day play an important role in gold recycling as well.

“The profit generated by the recovered gold is more than 200 times the cost of the hybrid membrane,” says Mezzenga.

The filter itself is very made of simple and inexpensive products, but what about making it work? Next we look at how it works.