A new discovery made by scientists in the US shows that a type of foam called chalcogel could finally solve the problem of the infiltration of heavy metals in Earth’s sources of water.

 The discovery, reported in the latest issue of Science magazine, has proven to be the ideal cleaner for waters infested with heavy metals like cadmium, lead or mercury.

Chalcogel is a rigid material that can be used to clean not only waters, but also other environments where the so-called “molecular sieves” are required.

A molecular sieve is a material containing tiny pores of a precise and uniform size that is used as an adsorbent for gases and liquids.

Molecules small enough to pass through the pores are adsorbed while larger molecules are not. It is different from a common filter in that it operates on a molecular level. For instance, a water molecule may be small enough to pass through while larger molecules are not. Because of this, they often function as a desiccant. A molecular sieve can adsorb water up to 22% of its own weight.

Unlike molecular sieves, chalcogels are particularly fond of heavy metals resulted from the industrial processing of coal, paper manufacturing and the chlor-alkali industry - which manufactures chlorine and caustic soda.

Their remarkable properties are derived from their chemical structure: chalcogels are actually a special type of “aerogels”- a low-density material derived from a gel in which the liquid component has been replaced by gas. Aerogels are nicknamed frozen smoke, solid smoke or blue smoke due to its semi-transparent nature and the way light scatters in the material.

Mercouri Kanatzidis, a chemist at Northwestern University in Illinois, US, and his colleagues obtained the chalcogels by linking clusters of chemical groups called chalcogenides with charged metal atoms - called metal ions. The elements sulphur and selenium are examples of chalcogenides.

Other useful properties of chalcogels are their lightness (since they are mostly made of air) and their enormous surface areas.

"A few cubic centimetres of this stuff has such a big surface area that if you were to unfold it, it would cover one football field," Dr Kanatzidis told the BBC News website.

"This surface area is so big that sooner or later, anything that goes into that material will hit the surface."

Worthy mentioning is chalcogels’ predilection for heavy and toxic metals, because of the sulphur and selenium that compose them.