An environmentally friendly strategy for recovering gold from gold-bearing waste materials is reported in Nature Communications this week. The process relies on the perfect “host-guest” interaction between gold bromide salts and alpha-cyclodextrin - a simple, non-toxic carbohydrate that can be produced from starch.
The price of gold has increased four times in the past ten years, so there is a clear incentive for its recovery from ores and consumer electronics waste. Current processes rely on highly toxic cyanide salts to “leach” the gold, and so have associated environmental and financial costs. Fraser Stoddart and colleagues show that the “supramolecular” interactions between alpha-cyclodextrin and gold salts allow the effective and selective recovery of gold from simulated and real waste materials, even in the presence of similar metals such as platinum and palladium.
It is hoped that finding this will pave the way for more economically viable gold recovery, with lower risks of environmental contamination.