Foam targets heavy metal clean-up

A type of porous foam can be used to soak up heavy metals from water, a team has reported in the journal Science.

The rigid material could be used for environmental clean-ups and other jobs that require so-called "molecular sieves" that can trap heavy metals.

Previously, materials called oxides have been used as molecular sieves, but these prefer to form bonds with small metal ions such as magnesium and zinc.

But the new foam preferentially absorbs heavy metals like mercury.

Toxic heavy metals in air, soil and water are a growing problem, threatening the health of populations around the world.

Sources of heavy metal pollution include coal, natural gas, paper and the chlor-alkali industry - which manufactures chlorine and caustic soda.

Mercouri Kanatzidis, a chemist at Northwestern University in Illinois, US, and colleagues developed a type of "aerogel" - a low-density material derived from a gel in which the liquid component has been replaced by gas.

This highly absorbent aerogel is made by linking clusters of chemical groups called chalcogenides with charged metal atoms - called metal ions. The elements sulphur and selenium are examples of chalcogenides.
more from BBC