Golden stripper evicts mercury

Gold nanoparticles can be used to strip mercury ions from contaminated water in a twenty-first century process that resembles the centuries-old method for extracting gold from its ore. Victor Puntes at the Catalan Institute of Nanotechnology in Barcelona, Spain, and colleagues recalled that recalled that gold miners exploit mercury-gold amalgams to extract the precious metal from its ore and leave behind mercury salts. The team has now reversed this process to pull the mercury from samples of contaminated water. The team used 9-nanometer gold nanoparticles coated with sodium citrate. The coating not only allows the nanoparticles to disperse in solution, but the citrate reduces any dissolved mercury to elemental mercury, which is much more readily separated from the water.