New material can soak up pollutants

Aerogel picks up mercury and lead like a sponge, researchers say

• A new porous material can soak up heavy metals from liquids like a sponge, researchers said Thursday, offering a host of potential uses including removing pollutants such as mercury or lead from water.
  
• The material is an aerogel, a type of rigid foam made from a gel in which most of the liquid has been replaced by gas.
  
• “What we’ve made is a new kind of aerogel that is made of the same stuff that semiconductors are made of,” said Mercouri Kanatzidis, a researcher with Northwestern University in Evanston, Illinois, and the U.S. Department of Energy’s Argonne National Laboratory.
• Classical aerogels — which are made of silica or carbon — have been around for many decades. “They are white and colorless and don’t absorb any light,” Kanatzidis said in a telephone interview.
  
• Kanatzidis has made aerogels from chalcogenides, which are used in semiconductors. “These new aerogels absorb light and they can be changed in composition from one kind to another,” said Kanatzidis, whose work appears in the journal Science.
  
• He and colleagues placed this new gel in a solution containing smaller metal ions and larger, highly toxic metal ions such as mercury. The aerogel removed almost all of the mercury from the solution and also a number of organic compounds.
  
• “It is very much like a sponge, only the walls of this sponge have a surface that presents sulfur atoms to the solution,” he said.
  
• “Mercury likes to bind with sulfur,” he said.
• The solution used in the experiment contained platinum, which is far too expensive for widespread environmental use.
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• We need to replace the platinum with cheaper elements,” he said.
  But Kanatzidis said he believed it was possible and his lab had already had some success with this.