Gold mined using cornstarch

Ways to recover gold from rock or waste often require environmentally hazardous chemicals. As the price of gold continues to rise, along with the incentive to mine it, the development of eco-friendly chemicals for its extraction and recovery becomes ever more important.

In a new study published in Nature Communications¹, a joint team of researchers from the United States and Saudi Arabia, led by Zhichang Liu from Northwestern University in Evanston, Illinois, have discovered a greener method to recover gold using alpha-cyclodextrin: a cheap and environmentally friendly carbohydrate derived from starch.

Using scanning, transmission electron and atomic force microscopies, they report that in solution, the dissolved gold salt KAuBr4 and alpha-cyclodextrin rapidly form a complex that can be isolated even in the presence of other metals such as palladium and platinum, which are often found mixed with crude gold.

They also found that the formation of this complex was highly specific and that it did not form when other types of cyclodextrins or an alternative gold salt were used.

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